secondary crushing equipment

secondary crushing equipment

The term secondary crushing has become well established and familiar through long usage; it applies to the crushing stage, either single or multiple, which follows immediately after the primary crusher, taking all or a portion of the product of the primary crushing stage as its feed. The term should not be used, as it sometimes is, to designate a particular type or size of crusher because any type and size might conceivably be used for secondary crushing. A very large number of secondary crushers in our present-day plants were originally primary crushers in those same plants. Secondary and second-stage are synonymous, and are equally good and descriptive definitions.

The termtertiary has been used rather extensively in recent years to cover not only third-stage crushers, but in a more general sense to delineate any and all crushers in the reduction and fine-reduction classes; a use which certainly takes liberties with the intent of the word. It is a legitimate term as applied strictly to a third stage of reduction, just as quaternary may be used to designate a fourth stage. Our own preference is to designate these successive reductions as third-stage, fourth-stage, and so on, and to identify the crushers themselves by the titles which usage has conferred upon them.

Reduction-crushers and reduction-crushing, through the same authority of common usage, have been narrowed from the broad scope of their definitions to delineate reductions in the intermediate sizes of product, loosely in the range between 3 and 1 screen sizes. Fine-reduction, in the same fashion, has come to cover the production of sizes in the range below 1, approximately. More recently still, the fine crusher has been introduced to extend the application of the gyratory type down into that borderland between crushing and grinding formerly monopolized by the crushing rolls and the hammermill.

The simplest form of secondary crushing stage involves a single crusher, taking its feed by gravity flow direct from the primary with no interposed scalping separation. This is tantamount to making the over-all reduction in one machine, except of course that there will always be a certain amount of surge capacity between the two crushers. This type of installation has been used in a number of plants, starting with the advent of the power shovel and the large primary crusher, many of which were tacked on to existing plants during the conversion from hand-loading to shovel-loading operation. Probably the most notable of such installations were those of the first jaw crushers of the 84 class. These big machines were designed to operate at rather coarse discharge settings, usually from 10 to 12, and the usual practice was to follow them with gyratory crushers such as the No. 9 (21) or No. 10 (24), the over-all ratio-of-reduction for the two machines being 14 or 15 to 1.

The simple two-crusher, screenless arrangement works out fairly well for the large sizes of primary jaw crushers if the quarry-run rock is reasonably clean, or if any fine material which may be present in the feed is free flowing. The arrangement is not advisable under any circumstances if the setting of the secondary crusher is to be less than about 5 in.; for finer settings than this the fines produced through the two stages are apt to promote a sluggish action in the secondary machine, which might under certain conditions build up to a complete choke in this stage.

So far as the commercial crushed stone plant is concerned the method violates the well established and very desirable principle of scalping off fines between all crushing stages in order to minimize further production of fines by attrition. The safest practice in all cases is to scalp between the primary and secondary stages regardless of the sizes of crushers used or their discharge settings. A plain grizzly is better than nothing; a modern heavy- duty vibrating screen is the ideal heavy-duty scalper.

The capacity of the secondary crushing stage need not necessarily match that of the primary crusher; more often than not it can be substantially less, for reasons outlined in the preceding section. It must of course be adequate to handle its share of the total plant capacity. How much its capacity should exceed the average plant capacity will depend upon how the job is engineered. If the installation is of the simple one-two variety we have just described, and very little surge capacity is provided between the two stages, the capacity of the secondary stage should at least equal that of the primary; otherwise the quarry equipment may be held up at times, waiting on the secondary crushing stage to clear itself. If, on the other hand, an adequate surge is provided to take care of the inevitable fluctuations in feed-rate to the primary, the capacity of the secondary stage may he predicated on requirements of the succeeding stages. This presupposes that the secondary machine or machines will be large enough to eliminate delays due to bridging or blocking of the feed from the primary.

If scalping between the two stages .is resorted to, the rating of the secondary stage may be reduced by whatever amount of undersize material is to be removed from the product of the primary. This can be determined within reasonably close limits by means of the product-gradation curves we have presented. In making this calculation it should be remembered that the scalping screen, regardless of type or size, will not remove all of the undersize. From 85 to 90% efficiency is the usual range, therefore the 10 or 15% undersize which will be carried over must be added to the theoretical tonnage, as figured from the curves, in arriving at the estimated feed to the secondary stage.

Once the required capacity for the secondary stage has been determined, it may be checked against tabulated ratings, at the desired discharge setting, for the type of crusher being considered for the stage. In making this check it should be remembered that capacity tables, while they are prepared on a conservative basis, are predicated upon a uniform rate of feed; and upon the assumption that the crusher is in first-class condition.

If for any reason it is expected that the feed rate will not be uniform, adequate allowance should be made for whatever degree of fluctuation is anticipated, just as was suggested for the primary crusher. Also, inasmuch as it is to be expected that some drop in efficiency of the crushers will occur from time to time because of mechanical conditions, some allowanceshould be made for this, regardless of whether or not the feed rate will be uniform. From 10 to 15% will be sufficient for this in a properly maintained plant.

Surge storage between the primary and secondary stages, while always theoretically desirable, may not always be practicable or economical. The product of the very large sizes of jaw crusher, for example, may be so coarse and slabby that it would be exceedingly difficult to handle through a surge bin or on mechanical feeders of reasonable size and cost. Therefore, where these large jaw crushers comprise the primary stage, it is generally best to consider the two stages as a unit and to match their capacities closely enough so that the material can be kept on the move; providing only a small open surge space between them. Then, if surge storage is desired it may be incorporated in the flow line after the secondary stage. The product of the largest sizes of gyratory crushers can be handled satisfactorily through storage.

primary crushing

primary crushing

The term primary crusher, by definition, might embrace any type and size of crushing machine. The term implies that at least two stages of crushing are involved, but in many cases the machine which performs the function of initial crusher is the only crusher in the plant. The factors influencing the selection of a crusher for this service are much the same, regardless of how many crushing stages there are in the flowsheet; therefore, the term primary crusher, by common usage, is applied to the crusher which takes up the job of reduction where the blasting operations leave off. Selecting the right type and size of primary crusher is a problem of prime importance in the designing of a crushing plant of any nature and size. Usually this machine is the largest and most expensive single item of equipment in the plant; a mistake in the choice can only be remedied fully by replacement; and, because the entire primary crusher-house arrangement is generally tailored.to fit the crusher, such .replacement is almost always a costly procedure. While personal favouritism toward some particular type of crusher may safely be allowed to swing a close decision, it should never blind the engineer or operator to the merits of other types, nor to the limitations of his favorite. The following factors all have a more or less important bearing upon the choice of the primary crusher.

The first three of these factors will almost always be ascertainable at least to a close approximation before the matter of crusher choice is taken up. Sometimes, as when a new crushing plant, or a new primary crusher set-up, is to be installed at an existing operation the last three factors will be pre-established. Otherwise, it is sound practice to consider them as a part of the problem of crusher selection. The primary crushing setup is closely linked to the quarrying or mining operation, and it is only by careful adjustment of all equipment selections to the general plan of operation that optimum operating results may be realized.

While it is convenient to discuss the influence of these several factors separately, it is well to keep in mind that they are more or less closely interlocked, and that a change in one of them may necessitate altering one or more of the others.In addition to the factors listed there are usually a few which are peculiar to each individual problem such as labor costs and so on. Any plant design problem is an economic as well as an engineering one. We are concerned here ,chiefly with the engineering phases.

Characteristics of the material to be crushed include the geological classification of the rock, its physical structure, its chemical analysis (at least so far as abrasive constituents are concerned), and at least a qualitative evaluation of its resistance to crushing that is, whether soft, medium, hard, or very hard and tough. Frequently such information may be obtained from contiguous deposits which are being operated; sometimes the values must be arrived at by laboratory tests. It is never safe to make blanket assumptions, even on such a material as limestone, which can sometimes prove to be quite tough, as well as to contain significant amounts of abrasive silica.

Physical, or geological, structure of the deposit often has an important bearing upon selection of size or type, or both. If the deposit is thinly stratified, as, for example, many deposits of limestone are, it is safe to assume that the rock can be blasted economically into a condition for feeding a gyratory crusher of medium proportions, or, if other characteristics are suitable, a sledging roll crusher, such as the Fairmount machine. If, on the other hand, the formation is of massive character, again, some limestones are, the gyratory crusher might be ruled out in favour of the jaw crusher, unless the operation is of sufficient magnitude to warrant installation of a large size of gyratory. The proposed quarrying or mining procedure will of course have some bearing upon the size of rock to go to the crusher, regardless of its physical structure, as will be pointed out in further detail later on. If the chemical analysis of the rock discloses that substantial amounts of free silica or any other abrasive are present, crushers of the sledging roll or hammermill types are usually ruled out unless the material is extremely soft and friable. There are occasional speciality applications where such machines may be indicated for crushing abrasive materials, but from the standpoint of, economical operation their use for such service is rarely justifiable. The same restriction holds true for hard and tough materials. For such rock or ore our choice of a primary crusher is restricted to the gyratory and jaw types except, again, for the occasional specialty application where economy in maintenance may be sacrificed for other considerations such as lower first cost, or space restrictions.

The significance of this factor is so obvious that it sometimes does not receive quite as much thought as it should. From the standpoint of minimum requirement, it is of course closely tied up with product size, or crusher setting. But the primary crusher can seldom be chosen solely on the basis of capacity; it should never be selected with a view to just meeting the average capacity required to feed the rest of the crushing plant. Just how much the rated capacity of the primary crusher (at the required discharge setting) should exceed the average capacity of the plant depends upon how uniformly the crusher will be fed; or to put it more definitely, what percentage of the total operating period the crusher will operate at full rated capacity. The answer to this is not always an easy one to predetermine, as it may depend upon several details of plant design and quarry operation.

In the average quarry operation, the only surge capacity between the quarry and the primary crusher consists of whatever quantity of rock may be, at the moment, loaded in cars or trucks, and usually this is not large. For that reason, any operating delays occurring in loading, transportation or primary crushing quickly affect all three of them, with the result that the feed to the balance of the crushing plant is cut-off until the trouble is rectified. If the plant as a whole is to maintain its rated average output, these departments must be capable of making up for such interruptions, and they can only do this if they have reserve capacity over and above the average requirement.

Such interruptions to continuous production are not uncommon in the primary crusher house; they may assume serious proportions if the crusher receiving opening is not large enough for the material it is expected to handle, and the largest crushers of any type will occasionally bridge or block. Crusher capacity tables are predicated upon a continuous feed of rock of a size that will readily enter the crushing chamber; it is obvious therefore that a crusher whose rating just equals the average plant requirement would have no reserve to compensate for the conditions we have outlined. For the average quarry operation this reserve should be not less than 25 percent, and preferably about 50 percent.

Since the minimum dimension of the feed opening of a crusher determines the maximum size of lump that it can take, the choice of a primary breaker is dependent as much on the size of the feed as on the hourly tonnage. Thus a 15 in. by 24 in. jaw crusher would be suitable for a small mine hoisting 300 tons in eight hours from underground workings from which lumps larger than 14 in. are not likely to be received. A crusher of these dimensions will break 40 tons per hour to 2-in. size with a power consumption of 30 h.p. On the other hand, a 14-in. gyratory crusher, working as it should at full capacity, will crush 100 tons per hour to the same size with a power consumption of 70 h.p. ; at 40 tons per hour, it would still require about 50 h.p. The jaw crusher is evidently the more economical machine in this case, and its first cost is only about half that of the gyratory crusher.

If the capacity of the primary breaker is required to be 100 tons per hour or over, a gyratory crusher is likely to be more economical than the other type, since it costs no more than a jaw crusher of similar capacity and consumes less power. Moreover, the difference in power consumption between the two types of machine is greater in practice than in theory; this is due to the fact that, since the gyratory crusher can be choke-fed, it is easier to keep it running at maximum efficiency.

The position is different when mining is done by power-shovel. The maximum size of lump delivered to the crushing plant is much larger than from underground workings, and it is not advisable to use a bin for the storage of the ore on account of the difficulty of handling very large lumps through a bin gate. Consequently the ore is generally sent direct to a preliminary breaker which reduces it to a size suitable for feeding the normal primary breaker. The first machine is often of the jaw type, although this depends on the circumstances. Suppose, to take an instance, that the shovels were equipped with 3-yd. dippers and that 2,000 tons were being mined per day. A 48 in. by 60 in. jaw crusher is more than large enough to take the maximum size of lump that could get through the jaws of the dipper, and it would break the whole days output to 6-in. size in eight hours with a power consumption of under 200 h.p. On the other hand, a 42-in. gyratory crusher, which is the smallest that could be installed with safety, has a maximum capacity of over 5,000 tons in eight hours with a power consumption of about 275 h.p. The jaw breaker would therefore be the more economical machine. It could, if necessary, be installed near the scene of mining operations, and would be set to deliver a 6- or 8-in. product, which could be conveniently transported to the crushing section of the flotation plant where it would be fed through the coarse ore bin to the primary breaker in the ordinary way.

The choice of a primary breaker is an individual problem for every installation. The type of mining and the regularity, size, and rate atwhich the ore is delivered, are the main determining factors, but all local conditions should be taken into consideration before a decision is made.

p&q university lesson 7- crushing & secondary breaking : pit & quarry

p&q university lesson 7- crushing & secondary breaking : pit & quarry

In the quarry, crushing is handled in four potential stages: primary, secondary, tertiary and quaternary. The reduction of aggregate is spread over these stages to better control the product size and quality, while minimizing waste.

The primary stage was once viewed merely as a means to further reduce stone following the blast or excavation prior to secondary crushing. Today, primary crushing is viewed as more important within the balance of production and proper sizing needs. The size and type of the primary crusher should be coordinated with the type of stone, drilling and blasting patterns, and the size of the loading machine. Most operations will use a gyratory, jaw or impact crusher for primary crushing.

In the secondary and subsequent stages, the stone is further reduced and refined for proper size and shape, mostly based on specifications to produce concrete and asphalt. Between stages, screens with two or three decks separate the material that already is the proper size. Most secondary crushers are cone crushers or horizontal-shaft impact crushers. Tertiary and quaternary crushers are usually cone crushers, although some applications can call for vertical-shaft impact crushers in these stages.

A gyratory crusher uses a mantle that gyrates, or rotates, within a concave bowl. As the mantle makes contact with the bowl during gyration, it creates compressive force, which fractures the rock. The gyratory crusher is mainly used in rock that is abrasive and/or has high compressive strength. Gyratory crushers often are built into a cavity in the ground to aid in the loading process, as large haul trucks can access the hopper directly.

Jaw crushers are also compression crushers that allow stone into an opening at the top of the crusher, between two jaws. One jaw is stationary while the other is moveable. The gap between the jaws becomes narrower farther down into the crusher. As the moveable jaw pushes against the stone in the chamber, the stone is fractured and reduced, moving down the chamber to the opening at the bottom.

The reduction ratio for a jaw crusher is typically 6-to-1, although it can be as high as 8-to-1. Jaw crushers can process shot rock and gravel. They can work with a range of stone from softer rock, such as limestone, to harder granite or basalt.

As the name implies, the horizontal-shaft impact (HSI) crusher has a shaft that runs horizontally through the crushing chamber, with a rotor that turns hammers or blow bars. It uses the high-speed impacting force of the turning blow bars hitting and throwing the stone to break the rock. It also uses the secondary force of the stone hitting the aprons (liners) in the chamber, as well as stone hitting stone.

With impact crushing, the stone breaks along its natural cleavage lines, resulting in a more cubical product, which is desirable for many of todays specifications. HSI crushers can be primary or secondary crushers. In the primary stage, HSIs are better suited for softer rock, such as limestone, and less abrasive stone. In the secondary stage, the HSI can process more abrasive and harder stone.

Cone crushers are similar to gyratory crushers in that they have a mantle that rotates within a bowl, but the chamber is not as steep. They are compression crushers that generally provide reduction ratios of 6-to-1 to 4-to-1. Cone crushers are used in secondary, tertiary and quaternary stages.

With proper choke-feed, cone-speed and reduction-ratio settings, cone crushers will efficiently produce material that is high quality and cubical in nature. In secondary stages, a standard-head cone is usually specified. A short-head cone is typically used in tertiary and quaternary stages. Cone crushers can crush stone of medium to very hard compressive strength as well as abrasive stone.

The vertical shaft impact crusher (or VSI) has a rotating shaft that runs vertically through the crushing chamber. In a standard configuration, the VSIs shaft is outfitted with wear-resistant shoes that catch and throw the feed stone against anvils that line the outside of the crushing chamber. The force of the impact, from the stone striking the shoes and anvils, fractures it along its natural fault lines.

VSIs also can be configured to use the rotor as a means of throwing the rock against other rock lining the outside of the chamber through centrifugal force. Known as autogenous crushing, the action of stone striking stone fractures the material. In shoe-and-anvil configurations, VSIs are suitable for medium to very hard stone that is not very abrasive. Autogenous VSIs are suitable for stone of any hardness and abrasion factor.

Roll crushers are a compression-type reduction crusher with a long history of success in a broad range of applications. The crushing chamber is formed by massive drums, revolving toward one another. The gap between the drums is adjustable, and the outer surface of the drum is composed of heavy manganese steel castings known as roll shells that are available with either a smooth or corrugated crushing surface.

Double roll crushers offer up to a 3-to-1 reduction ratio in some applications depending on the characteristics of the material. Triple roll crushers offer up to a 6-to-1 reduction. As a compressive crusher, the roll crusher is well suited for extremely hard and abrasive materials. Automatic welders are available to maintain the roll shell surface and minimize labor expense and wear costs.

These are rugged, dependable crushers, but not as productive as cone crushers with respect to volume. However, roll crushers provide very close product distribution and are excellent for chip stone, particularly when avoiding fines.

Hammermills are similar to impact crushers in the upper chamber where the hammer impacts the in-feed of material. The difference is that the rotor of a hammermill carries a number of swing type or pivoting hammers. Hammermills also incorporate a grate circle in the lower chamber of the crusher. Grates are available in a variety of configurations. The product must pass through the grate circle as it exits the machine, insuring controlled product sizing.

Hammermills crush or pulverize materials that have low abrasion. The rotor speed, hammer type and grate configuration can be converted for different applications. They can be used in a variety of applications, including primary and secondary reduction of aggregates, as well as numerous industrial applications.

Virgin or natural stone processing uses a multi-stage crushing and screening process for producing defined aggregate sizes from large lumps of rock. Such classified final fractions are used as aggregates for concrete, asphalt base, binder and surface course layers in road construction, as well as in building construction. The rock is quarried by means of drilling and blasting. There are then two options for processing the bulk material after it has been reduced to feeding size of the crushing plant: mobile or stationary plants.

When stone is processed in mobile primary crushing plants, excavators or wheel loaders feed the rock into the crusher that is set up at the quarry face, gravel pit or in a recycling yard or demolition site. The crushed material is then either sent to the secondary/tertiary processing stage via stacking conveyors or transported by trucks. Some mobile crushers have an independent secondary screen mounted on the unit, effectively replacing a standalone screen.

The higher the compressive strength of rock, the higher also is its quality, which plays an important role particularly in road construction. A materials compressive strength is delineated into hard, medium-hard or soft rock, which also determines the crushing techniques used for processing to obtain the desired particle sizes.

The materials quality is influenced significantly by particle shape. The more cubic-shaped the individual aggregate particles are, the better the resulting particle interlock. Final grains of pronounced cubic shape are achieved by using several crushing stages. A cubicity showing an edge ratio of better than 1-to-3 is typical of high-quality final aggregate.

As the earths natural resources are becoming ever more scarce, recycling is becoming ever more important. In the building industry, recycling and reuse of demolition concrete or reclaimed asphalt pavement help to reduce the requirements for primary raw materials. Mobile impact and jaw plants are uniquely positioned to produce high-quality reclaimed asphalt pavement (RAP) and recycled concrete aggregate (RCA) for reuse in pavements, road bases, fill and foundations.

Use of RAP and RCA is growing dramatically as road agencies accept them more and more in their specs. But because RAP and RCA come from a variety of sources, to be specified for use by most departments of transportation they must be processed or fractionated and characterized into an engineered, value-added product. RCA or RAP are very commonly crushed and screened to usable sizes often by impact crushers and stored in blended stockpiles that can be characterized by lab testing for use in engineered applications.

Impact crushers are increasingly used for crushing recycling material. Impact crushers are capable of producing mineral aggregate mixes in one single crushing stage in a closed-cycle operation, making them particularly cost-effective. Different crusher units can alternatively be combined to process recycling material. A highly efficient method of processing recycling material combines crushing, screening and separation of metals. To produce an end product of even higher quality, the additional steps of washing to remove light materials such as plastics or paper by air classification and via electromagnetic metal separator are incorporated into the recycling process.

Mobile impact crushers with integrated secondary screens or without integrated screen used in conjunction with an independent mobile screen are ideal for producing large volumes of processed, fractionated RAP or RCA on a relatively small footprint in the plant. Mobile impactors are especially suited for RAP because they break up chunks of asphalt pavement or agglomerations of RAP, rather than downsize the aggregate gradation. Compression-type crushers such as jaws and cones can clog due to packing (caking) of RAP when the RAP is warm or wet.

Contaminants such as soil are part of processing demolition concrete. Mobile impact and jaw crushers when possessing integrated, independent prescreens removing dirt and fines before they ever enter the crushing circuit reduce equipment wear, save fuel, and with some customers, create a salable fill byproduct. A lined, heavy-duty vibrating feeder below the crusher can eliminate belt wear from rebar or dowel or tie bar damage. If present beneath the crusher, this deflector plate can keep tramp metal from degrading the conveyor belt. That way, the feeder below the crusher not the belt absorbs impact of rebar dropping through the crusher.

These mobile jaw and impact crushers may feature a diesel and electric-drive option. In this configuration, the crusher is directly diesel-driven, with the conveyor troughs, belts and prescreen electric-driven via power from the diesel generator. This concept not only reduces diesel fuel consumption, but also results in significantly reduced exhaust emissions and noise levels. This permits extremely efficient operation with low fuel consumption, allowing optimal loading of the crusher.

Jaw crushers operate according to the principle of pressure crushing. The raw feed is crushed in the wedge-shaped pit created between the fixed crusher jaw, and the crusher jaw articulated on an eccentric shaft. The feed material is crushed by the elliptic course of movement and transported downwards. This occurs until the material is smaller than the set crushing size.

Jaw crushers can be used in a wide range of applications. In the weight class up to 77 tons (70 metric tons), they can be used for both virgin stone and recycled concrete and asphalt aggregates processing as a classic primary crusher for natural stone with an active double-deck grizzly, or as a recycling crusher with vibrating discharge chute and the crusher outlet and magnetic separator.

Output for mobile jaw crushers ranges from 100 to 1,500 tph depending on the model size and consistency of the feed material. While larger mobile crushers produce more aggregate faster, transport weights and dimensions may limit how easily the crusher can be shipped long distances. Mobile jaw crushers can have either a vibratory feeder with integrated grizzly, or a vibrating feeder with an independent, double-deck, heavy-duty prescreen. Either way, wear in the system is reduced because medium and smaller gradations bypass the crusher, with an increase in end-product quality because a side-discharge conveyor removes fines. A bypass flap may provide easy diversion of the material flow, eliminating the need for a blind deck.

Jaw crusher units with extra-long, articulated crusher jaws prevent coarse material from blocking while moving all mounting elements of the crusher jaw from the wear area. A more even material flow may be affected if the transfer from the prescreen or the feeder trough is designed so material simply tilts into the crushing jaw.

Mobile jaw and impact crushers alike can be controlled by one operator using a handheld remote. The remote also can be used to move or relocate the crusher within a plant. In other words, the crusher can be run by one worker in the cab of an excavator or loader as he feeds material into the crusher. If he sees something deleterious going into the hopper, he can stop the crusher.

Impact crushing is totally different from pressure crushing. In impact crushing, feed material is picked up by a fast moving rotor, greatly accelerated and smashed against an impact plate (impact toggle). From there, it falls back within range of the rotor. The crushed material is broken again and again until it can pass through the gap between the rotor and impact toggle.

A correctly configured mobile jaw or impact crusher will enhance material flow through the plant and optimize productivity. New-design mobile jaw and impact crushers incorporate a highly efficient flow concept, which eliminates all restriction to the flow of the material throughout the entire plant. With this continuous-feed system, each step the material goes through in the plant is wider than the width of the one before it, eliminating choke or wear points.

For example, a grizzly feeder can be wider than the hopper, and the crusher inlet wider than the feeder. The discharge chute under the crusher is 4 inches wider than the inner width of the crusher, and the subsequent discharge belt is another 4 inches wider than the discharge chute. This configuration permits rapid flow of crushed material through the crusher. Also, performance can be significantly increased if the conveying frequencies of the feeder trough and the prescreen are adapted independently to the level of the crusher, permitting a more equal loading of the crushing area. This flow concept keeps a choke feed to the crusher, eliminating stops/starts of the feed system, which improves production, material shape and wear.

Users are focused on cost, the environment, availability, versatility and, above all, the quality of the end product. Simple crushing is a relatively easy process. But crushing material so that the particle size, distribution and cleanliness meet the high standards for concrete and asphalt requires effective primary screening, intelligent control for optimal loading, an adjustable crusher with high drive output, and a screening unit with oversize return feed.

This starts with continuous flow of material to the crusher through a variable-speed control feeder. Having hopper walls that hydraulically fold integrated into the chassis makes for quick erection of hopper sides on mobile units. If available, a fully independent prescreen for either jaw or impact models offers the ability to effectively prescreen material prior to crushing this allows for product to be sized prior to crushing, as opposed to using a conventional vibrating grizzly. This has the added value of increasing production, reducing wear costs and decreasing fuel consumption.

This independent double-deck vibrating screen affects primary screening of fines and contaminated material via a top-deck interchangeable punched sheet or grizzly, bottom-deck wire mesh or rubber blank. Discharged material might be conveyed either to the left or to the right for ease of positioning. The independent double-deck vibrating prescreen improves flow of material to the crusher, reducing blockages and feed surges.

Modern electrical systems will include effective guards against dust and moisture through double-protective housings, vibration isolation and an overpressure system in which higher air pressure in the electrical box keeps dust out. Simple and logical control of all functions via touch panel, simple error diagnostics by text indicator and remote maintenance system all are things to look for. For crushing demolition concrete, look for a high-performance electro- or permanent magnet with maximum discharge capacity, and hydraulic lifting and lowering function by means of radio remote control.

For impact crushers, a fully hydraulic crusher gap setting with automatic zero-point calculation can speed daily set-up. Featured only on certain mobile impact crushers, a fully hydraulic adjustment capability of the crushing gap permits greater plant uptime, while improving quality of end product.

Not only can the crushing gap be completely adjusted via the touch panel electronic control unit, but the zero point can be calculated while the rotor is running. This ability to accurately set the crusher aprons from the control panel with automatic detection of zero-point and target-value setting saves time, and improves the overall efficiency and handling of the crusher. On these mobile impact crushers, the zero point is the distance between the ledges of the rotor and the impact plates of the lower impact toggle, plus a defined safety distance. The desired crushing gap is approached from this zero point.

While the upper impact toggle is adjusted via simple hydraulic cylinders, the lower impact toggle has a hydraulic crushing gap adjustment device, which is secured electronically and mechanically against collision with the rotor. The crushing gap is set via the touch screen and approached hydraulically. Prior to setting of the crushing gap, the zero point is determined automatically.

For automatic zero-point determination with the rotor running, the impact toggle moves slowly onto the rotor ledges until it makes contact, which is detected by a sensor. The impact toggle then retracts to the defined safe distance. During this procedure, a stop ring slides on the piston rod. When the zero point is reached, the locking chamber is locked hydraulically and the stop ring is thus fixed in position. The stop ring now serves as a mechanical detent for the piston rod. During the stop ring check, which is carried out for every crusher restart, the saved zero point is compared to the actual value via the electronic limit switch. If the value deviates, a zero-point determination is carried out once again.

These impact crushers may feature a new inlet geometry that allows even better penetration of the material into the range of the rotor. Also, the wear behavior of the new C-form impact ledges has been improved to such an extent that the edges remain sharper longer, leading to improved material shape.

The machines come equipped with an efficient direct drive that improves performance. A latest-generation diesel engine transmits its power almost loss-free directly to the crushers flywheel, via a fluid coupling and V-belts. This drive concept enables versatility, as the rotor speed can be adjusted in four stages to suit different processing applications.

Secondary impact crushers and cone crushers are used to further process primary-crushed aggregate, and can be operated with or without attached screening units. These crushers can be used as either secondary or tertiary crushers depending on the application. When interlinked to other mobile units such as a primary or screen, complicated technical processing can be achieved.

Mobile cone crushers have been on the market for many years. These machines can be specially designed for secondary and tertiary crushing in hard-stone applications. They are extraordinarily efficient, diverse in application and very economical to use. To meet the diverse requirements in processing technology, mobile cone crushing plants are available in different sizes and configurations. Whether its a solo cone crusher, one used in addition to a triple-deck screen for closed-loop operation, or various-size cone crushers with a double-deck screen and oversize return conveyor, a suitable plant will be available for almost every task.

Mobile cone crushers may be available with or without integrated screen units. With the latter, an extremely efficient triple-deck screen unit may be used, which allows for closed-loop operation and produces three final products. Here the screen areas must be large so material quantities can be screened efficiently and ensure that the cone crusher always has the correct fill level, which is particularly important for the quality of the end product.

Mobile, tracked crushers and screen plants are advancing into output ranges that were recently only possible using stationary plants. Previously, only stationary plants were used for complicated aggregate processing applications. But thanks to the advancements made in machine technology, it is becoming increasingly possible to employ mobile technology for traditional stationary applications.

Mobile crushers are used in quarries, in mining, on jobsites, and in the recycling industry. These plants are mounted on crawler tracks and can process rock and recycling material, producing mineral aggregate and recycled building materials respectively for the construction industry. A major advantage of mobile crushers is their flexibility to move from one location to the next. They are suitable for transport, but can also cover short distances within the boundaries of their operating site, whether in a quarry or on the jobsite. When operating in quarries, they usually follow the quarry face, processing the stone directly on site.

For transport over long distances to a new location or different quarry, mobile crushers are loaded on low trailers. No more than 20 minutes to an hour is needed for setting the plant up for operation. Their flexibility enables the mobile crushers to process even small quantities of material with economic efficiency.

Mobile plants allow the combination of prescreening that prepares the rock for the crushing process and grading, which precisely separates defined aggregate particle sizes into different end products to be integrated with the crushing unit into one single machine. In the first stage, the material is screened using an active prescreen. After prescreening, it is transferred to the crusher, from where it is either stockpiled via a discharge conveyor or forwarded to a final screen or a secondary crushing stage. Depending on the specified end product, particles are then either graded by screening units or transported to additional crushing stages by secondary or tertiary impact crushers or cone crushers. Further downstream screening units are used for grading the final aggregate fractions.

The process of prescreening, crushing and grading is a common operation in mobile materials processing and can be varied in a number of ways. Mobile crushers with up to three crushing stages are increasingly used in modern quarries. Different mobile crushing and screening plants can be combined for managing more complex crushing and screening jobs that would previously have required a stationary crushing and screening plant.

Interlinked mobile plants incorporate crushers and screens that work in conjunction with each other, and are coordinated in terms of performance and function. Mining permits are under time constraints and mobile plants provide faster setup times. They provide better resale value and reusability, as mobile plants can also be used individually. They also reduce operating costs in terms of fewer haul trucks and less personnel.

With a so-equipped mobile crusher, the feed operator can shut the machine down or change the size of the material, all using the remote control, or use it to walk the crusher from one part of the site to the other, or onto a flat bed trailer for relocation to a different quarry or recycling yard. This reduces personnel and hauling costs compared to a stationary plant. With the mobile jaw or impact primary crusher, the only additional personnel needed would be a skid-steer operator to remove scrap steel, and someone to move the stockpiles.

Thanks to better technology, mobile plants can achieve final aggregate fractions, which previously only were possible with stationary plants. Production availability is on par with stationary plants. Theyre applicable in all quarries, but can be used for small deposits if the owner has several quarries or various operation sites. For example, an operator of several stone quarries can use the plants in changing market situations at different excavation sites. In addition, they also can be used as individual machines. A further factor is that mobile plants, in general, require simpler and shorter licensing procedures.

The high cost of labor keeps going up. A stationary crusher might be able to produce multiple times the amount of product, but also would require about seven or eight workers. Aggregate producers can benefit when producing material with the minimized crew used for mobile jaw and impact crushers.

Using correct maintenance practices, mobile crushers will remain dependable throughout their working life. Crushing and processing material can result in excessive wear on certain components, excessive vibration throughout the plant, and excessive dust in the working environment. Some applications are more aggressive than others. A hard rock application is going to require more maintenance on top of standard maintenance, as there will be more vibration, more dust and more wear than from a softer aggregate.

Due to the nature of its purpose, from the moment a mobile crusher starts, the machine is wearing itself out and breaking itself down. Without routine, regular maintenance and repair, a mobile crusher will not be reliable nor provide the material customers demand.

The first area of wear on any machine is the feed system. Whether its a feeder with an integrated grizzly, or a feeder with an independent prescreen, how the machine is fed contributes to wear. When setting up and maintaining a machine, the machine must be level. A machine that is unlevel left to right will experience increased wear on all components, including the feeder, the screens, the crushing chambers and the conveyor belts. In addition, it reduces production and screening efficiency, as the whole area of the machine is not being effectively used. Also, having the machine sit high at the discharge end will have the effect of feeding the material uphill in the feeder and reducing its efficiency, thus reducing production.

Another area for consideration is the equipment used to feed the machine. The operator using a loader to feed the crusher will have no control over the feed size, as he cannot see whats in the bucket. Whereas with an excavator, the operator can see whats inside and has more control over the feed into the hopper. That is, the operator is not feeding so much material all at once and is controlling the size of the feed. This reduces wear in the feed hoppers impact zones and eliminates material blockages due to feed size being too large to enter the chamber.

Dust is a problem in its own right, especially for the power plant of the mobile crusher. In a very dusty application, it is easy to plug the radiator and have engine-overheating problems. High dust levels cause increased maintenance intervals on air filters, and if not controlled properly, can enter the diesel tank and cause problems with the fuel system. Also, dust that gets inside the crusher increases wear. But if systems are put in place to remove the dust, it should keep it from going into the machine in the first place.

Dust also is a hazard on walkways and a problem for conveyors. If maintained, side-skirting and sealing the conveyors keeps dust from spilling out, building up underneath the conveyor, or building up in rollers, pulleys, bearings, and causing wear on shafts. Its important to maintain the sealing rubbers on the conveyor belts to avoid those issues. Routine maintenance calls for removing accumulated dust from inside and under the machine.

Dust also is a problem for circuit boards and programmable controllers. Dust causes electrical switches to malfunction because it stops the contacts from correctly seating. Electrical systems under positive air pressure dont permit dust to penetrate the control system. In control panels with a correctly maintained positive pressure system, filters remove dust from air that is being pumped into the cabinets. If the filters are plugged, the system will not pull as much air through, allowing dust, moisture and heat to build in the cabinet.

There are also impact aprons against which the rock is thrown, which also see high wear. There are side plates or wear sheets on the sides of the machine. The highest wear area is around the impact crusher itself, around the circumference of the rotor. If not maintained, the wear items will wear through and compromise the structure of the crusher box.

Conduct a daily visual check of the machine. The jaw is simple; just stand up on the walkway and take a look down inside. A crushers jaw plate can be flipped so there are two sides of wear on them. Once half the jaw is worn out, flip it; once that side is worn, change it.

The impact crusher will have an inspection hatch to see inside. Check to see how much material is left on the blow bars and how much is left on the wear sheets on the side of the crusher box. If half the bar is worn out after one week, change the blow bars in another week.The frequency of changes depends entirely on the application and the rock that is being crushed.

They have to be user serviceable, user friendly, and able to be changed in a short time. The best way to change these parts is a service truck with a crane; some use excavators but thats not recommended by any means.

After initial blasting, breakers are used to break down aggregate that typically is not only too large to be hauled in dump trucks, but also too large for crushers that size rock to meet asphalt, drainage system, concrete and landscaping specifications. Breakers can be mounted to a mobile carrier, such as an excavator, or to stationary boom systems that can be attached to a crusher. The total number of hydraulic breakers can vary from site to site depending on production levels, the type of aggregate materials and the entire scope of the operation.

Without hydraulic breakers, workers rely on alternative practices that can quickly affect production rates. For instance, blasting mandates shutting down operations and moving workers to a safe location. And when you consider how many times oversize aggregate might need to be reduced, this can lead to a significant amount of downtime and substantially lower production rates.

Aggregate operations can use hydraulic breakers to attack oversize without having to clear the quarry. But with an ever-growing variety of manufacturers, sizes and models to choose from, narrowing the decision to one hydraulic breaker can be overwhelming with all of the stats and speculation. Thats why its important to know what factors to consider before investing in a new hydraulic breaker.

In most cases, heavy equipment dealers are very knowledgeable about quarry equipment, including breakers, so they are a good resource for finding the best model for a carrier, usually an excavator or stationary boom system. More than likely, they will have specifications and information about various breaker sizes to help gauge what model is best. But being familiar with what to look for in a breaker can streamline the selection process.

The best places to look for breaker information are in the manufacturers brochure, website, owners manual or catalogue. First, carefully review the carrier weight ranges. A breaker that is too big for the carrier can create unsafe working conditions and cause excessive wear to the carrier. An oversized breaker also transmits energy in two directions, toward the aggregate and through the equipment. This produces wasted energy and can damage the carrier. But using a breaker thats too small puts excessive force on the tool steel, which transmits percussive energy from the breaker to the material. Using breakers that are too small also can damage mounting adapters and internal components, which considerably decreases their life.

Once you find a breaker that meets the carriers capacity, check its output power, which is typically measured in foot-pounds. Foot-pound classes are generalizations and are not based on any physical test. Often the breakers output will be documented in one of two ways: as the manufacturers calculated foot-pound class or as an Association of Equipment Manufacturers measured foot-pound rating. Foot-pound class ratings can be deceiving since they are loosely based on the breakers service weight and not the result of any physical test. The AEM rating, on the other hand, measures the force a breaker exerts in a single blow through repeatable and certified testing methods. The AEM rating, which was developed by the Mounted Breaker Manufacturers Bureau, makes it easier to compare breaker models by reviewing true figures collected during an actual test procedure.

For instance, three breaker manufacturers might claim their breakers belong in a 1,000-lb. breaker class. But AEM testing standards could reveal all three actually have less foot-pound impact. You can tell if a breaker has been AEM tested if a manufacturer provides a disclosure statement or if the breaker is labeled with an AEM Tool Energy seal. If you cannot find this information, contact the manufacturer. In addition to output energy specifications, manufacturers often supply estimates for production rates on different types of aggregate material. Make sure to get the right measurements to make the best decision.

In addition to weight and output power, look at the breakers mounting package. Two things are crucial for mounting a breaker to a carrier: a hydraulic installation kit and mounting components. Breakers need hydraulic plumbing with unidirectional flow to move oil from the carrier to the breaker and back again. A one-way flow hydraulic kit is sufficient to power the breaker as long as the components are sized to properly handle the required flows and pressures. But, consider a bidirectional flow hydraulic kit if you plan to use the same carrier with other attachments that require two-way flow. Check with the dealer or breaker manufacturer to determine which hydraulic package best fits current and future needs.

Hydraulic flow and pressure specifications also need to be considered when pairing a breaker to a hydraulic system. If the carrier cannot provide enough flow at the right pressure, the breaker wont perform with maximum output, which lowers productivity and can damage the breaker. Additionally, a breaker receiving too much flow can wear quickly, which reduces its service life. For the best results, follow the hydraulic breaker specifications found in owners manuals, catalogs and brochures. Youll find out if a breaker has additional systems that might require additional servicing. For instance, some breakers feature nitrogen gas-assist systems that work with the hydraulic oil to accelerate the breakers piston. The nitrogen systems specifications need to be followed for consistent breaker power output.

Brackets or pin and bushing kits are commonly required to attach the breaker to the carrier. Typically they are bolted to the top of a breaker and are configured to match a specific carrier. Some manufacturers make universal mounting brackets that can accommodate two or three different sizes of carriers. With the adjustable pins, bushings or other components inside these universal brackets, the breaker can fit a range of carriers. However, varying distances between pin centers can complicate hookups to quick coupling systems. In addition, loose components, such as spacers, can become lost when the breaker is not in use and detached from the carrier.

Some carriers are equipped with quick-coupling systems, which require a breakers mounting interface to be configured like the carriers original attachment. Some manufacturers produce top-mount brackets that pair extremely well with couplers. This allows an operator to use the original bucket pins from the carrier to attach the breaker, and eliminates the need for new pins. This pairing also ensures a fast pickup with the quick coupler.

Its also a good idea to check which breaker tools are available through the dealer and manufacturer. The most common for aggregate mining are chisels and blunts. There are two kinds of chisels commonly used in aggregate mines: crosscut and inline. Both chisels resemble a flat head screwdriver, but the crosscut chisels are used when carrier operators want to direct force in a left-to-right concentration; whereas, inline chisels direct force fore and aft. With chisel tools, operators can concentrate a breakers energy to develop cracks, break open seams or define scribe lines.

If a chisel cant access or develop a crack or seam, a blunt can be used. Blunts have a flattened head that spreads the energy equally in all directions. This creates a shattering effect that promotes cracks and seam separation. Ask your dealer if the tools you are considering are suited for the application. Using non-original equipment manufacturer tool steel can damage the percussive piston in the breaker, seize into the wear bushings, or cause excessive wear.

Regular breaker maintenance is necessary, yet its one of the biggest challenges for aggregate operations. It not only extends the life of the breaker, but also can keep minor inconveniences from turning into expensive problems. Some manufacturers recommend operators inspect breakers daily to check grease levels and make sure there are no worn or damaged parts or hydraulic leaks.

Breakers need to be lubricated with adequate amounts of grease to keep the tool bushing area clear and reduce friction, but follow the manufacturers recommendations. For example, adding grease before properly positioning the breaker can lead to seal damage or even catastrophic failure. And too little grease could cause the bushings to overheat, seize and damage tools. Also, manufacturers advise using high-moly grease that withstands working temperatures greater than 500 degrees. Some breakers have automatic lube systems that manage grease levels, but those systems still need inspections to ensure there is adequate grease in their vessels. Shiny marks on the tool are a good indication the breaker is not properly lubricated.

Little has changed in basic crusher design over past decades, other than that of improvements in speed and chamber design. Rebuilding and keeping the same crusher in operation year after year has long been the typical approach. However, recent developments have brought about the advent of new hydraulic systems in modern crusher designs innovations stimulated by the need for greater productivity as well as a safer working environment. Importantly, the hydraulic systems in modern crusher designs are engineered to deliver greater plant uptime and eliminate the safety risks associated with manual intervention.

Indeed the crushing arena is a hazardous environment. Large material and debris can jam inside the crusher, damaging components and causing costly downtime. Importantly, manually digging out the crusher before repairs or restarts puts workers in extremely dangerous positions.

The Mine Safety and Health Administration has reported numerous injuries and fatalities incurred when climbing in or under the jaw to manually clear, repair or adjust the typical older-style jaw crusher. Consider that fatalities and injuries can occur even when the machine is locked out and tagged out. Recent examples include a foreman injured while attempting to dislodge a piece of steel caught in the primary jaw crusher. Another incident involved a fatality when a maintenance man was removing the toggle plate seat from the pitman on a jaw crusher. The worker was standing on a temporary platform when the bolts holding the toggle seat were removed, causing the pitman to move and strike him.

The hydraulic systems on modern crusher designs eliminate the need for workers to place themselves in or under the crusher. An overview of hydraulic system technology points to these three key elements:

A hydraulic chamber-clearing system that automatically opens the crusher to a safe position, allowing materials to pass. A hydraulic overload relief that protects parts and components against overload damage. A hydraulic adjustment that eliminates the maintenance downtime associated with manual crusher adjustments, and maintains safe, consistent crusher output without the need for worker intervention.

Whether a crusher is jammed by large material, tramp iron or uncrushable debris; or is stalled by a power failure the chamber must be cleared before restarting. Manual clearing is a lengthy and risky task, especially since material can be wedged inside the crusher with tremendous pressure, and dislodging poses much danger to workers placed in harms way inside the crusher.

Unlike that of the older-style jaw, the modern jaw will clear itself automatically with hydraulics that open the crusher to a safe position, and allow materials to pass again, without the need for manual intervention. If a feeder or deflector plate is installed under the crusher, uncrushable material will transfer smoothly onto the conveyor without slicing the belt.

To prevent crusher damage, downtime and difficult maintenance procedures, the hydraulic overload relief system opens the crusher when internal forces become too high, protecting the unit against costly component failure. After relief, the system automatically returns the crusher to the previous setting for continued crushing.

The modern crusher is engineered with oversized hydraulic cylinders and a traveling toggle beam to achieve reliable overload protection and simple crusher adjustment. All closed-side setting adjustments are made with push-button controls, with no shims being needed at any time (to shim is the act of inserting a timber or other materials under equipment). This is a key development as many accidents and injuries have occurred during shim adjustment, a process which has no less than 15 steps as described in the primary crusher shim adjustment training program offered by MSHA.

secondary & tertiary crushing circuits

secondary & tertiary crushing circuits

In this sectoron Secondary and Tertiary crushing, we will continue the practice of talkingabout different equipment, the work it does, and the effects of what I call operating variables. These variables are anything that affect the performance of the equipment.

Lets begin with an over view of these two crushing stages. Then describe various flow sheets, and discuss the variables that influenced their design. After the whys have been given we will discuss the equipment and the operating techniques required to operate a modern crushing plant. The two major variables that determine the size of the crusher and the design of the flow-sheet are the tonnage through put required and the hardness of the ore. The tonnage will be determined by economic factors, namely what tonnage is required to make the mine profitable? The hardness of the ore is determined by what is known as the WORK INDEX. This measurement is determined by the resistance of the ore to breakage. It is discovered by the energy output required to reduce the ore to a specific predetermined size. It is measured by the KILOWATT PER HOUR usage of electricity required. Lets start with a very simple flow sheet. This one is designed for very soft rock, or where the product size isnt important.

The feed comes from the primary crusher and will have a certain amount of rock that doesnt need further crushing. To run this ore through the crusher will be a waste of energy and crushing space. Ideally it should be removed.

To remove it requires a procedure called SCALPING. This is when the ore is allowed to flow over a set of SCREENS or GRIZZLIES. The large ore wont be able to pass through the mesh, but the fine material will, this effectively separates the two sizes.

The ore is a little harder and the sizing more critical however, this means the positioning of the equipment has to change a little. The ore is still discharged from the primary crusher to the scalping equipment. For this type of application this is usually a screen. Again the fine material is removed from the circuit while the course gets crushed. But now, instead of continuing, the crushed product is directed back to the screen for further sizing. Any rock that isnt small enough will have to go through the crusher once more. Designing the circuit this way insures that the crushed rock has a uniform size.

Just for interest sake, the first circuit we looked at is called an OPEN CIRCUIT. This is because of the constant forward movement of ore. The second one is referred to as a closed circuit. That is because the ore must meet the circuits objective, in this case the correct size, before it is allowed to escape the closed loop of the crushing circuit.

Our last schematic represents a CLOSED CIRCUIT. This one involves both SECONDARY and TERTIARY crushing. This circuit is employed where either the tonnage or the work index of the ore is high enough to require that the crushing be done in stages.

Again the ore will come from a Primary crusher and be scalped. The coarse material will be crushed by the secondary crusher. The fines will be taken out of the circuit. Once the secondary has finished with the ore it will be reclassified by a second set of screens with the oversize going to the tertiary crusher. The discharge of the tertiary is reintroduced to the screen deck to ensure that the ore size is uniform. These three schematics are samples of crushing circuits. There are many other varieties, each one dictated by the requirements of the ore, and the economics involved. Although each mine has its own individual problems, and the resulting unique design, they do usually have one thing in common. Almost all secondary and tertiary crushing circuits use the same type of crusher, the cone crusher.

secondary crusher, secondary crushing plant - all industrial manufacturers - videos

secondary crusher, secondary crushing plant - all industrial manufacturers - videos

{{#each product.specData:i}} {{name}}: {{value}} {{#i!=(product.specData.length-1)}} {{/end}} {{/each}}

{{#each product.specData:i}} {{name}}: {{value}} {{#i!=(product.specData.length-1)}} {{/end}} {{/each}}

... mobile impact crusher is the most versatile and cost effective mid-sized unit on the market. Fitted with the CI411 Prisec impactor, this unit can operate in both primary and secondary applications.This ...

Sandvik QI441 mobile impact crusher is a pioneering solution offering primary and secondary crushing in one unit. Maximum productivity and efficiency in a single investment.This mobile impact crusher ...

... and covered for 1 year warranty! *Installation and Operator Training FREE Our cone crusher product group is designed especially for the hardest material, cone crushers are one of the best choices for ...

... cubical-shaped final product, Meka secondary impact crushers are great economical solutions for crushing both soft and hard materials such as river gravel, limestone and dolomite. The grinding type of ...

K series mobile crusher K SERIES MOBILE CRUSHING & SCREENING PLANT is researched to meet customers demand on high quality and high output, and it is widely used in almost every field in ore, construction, recycling, ...

... Applications: Secondary medium & fine crusher is widely used in mining, quarry, mixing and batching plant, road and building construction, highway, railway and subway, and water conservancy. Specifications ...

Mobile Impact Crusher Stable, Flexible, Efficient, Functional Mobile Impact Crusher can process medium hard stones, and final products can be used in road, bridge, construction and water conservancy, ...

... 700 mm Feed height (with extension)4,340 (4,700) mm Hopper capacity (with extension)5.0 (9.0) m Crusher inlet width x height1,300 x 900 mm Secondary screening unit width x length1,550 x 4,550 mm Drive ...

The MCO 9 can be used either as a secondary or tertiary crushing plant. Due to the low total weight, it is possible to change locations without great difficulty using a flat-bed trailer. In addition, all components can ...

... m Crusher diameter950 mm Drive conceptdiesel-direct Engine power LRC289 kW Engine power Tier 3/Stage IIIA289 kW Transport width 33,240 mm Transport length without (with) screening unit16,600 (20,770) mm Transport ...

... Jaw crushers are one of the most commonly preferred crushers due to their ability to crush all kinds of materials of any hardness, as well as their low-cost operation and easy maintenance USED TO ...

... stretching and belt stretching - - Spare parts and service books - - User and maintenance books Vertical Shaft Impact Crushers secondary, tertiary or quaternary stage crushing Two layers of anti-corrosion ...

The vertical shaft impact crusher is one of the most common manufactured sand equipment. GEP Ecotech's vertical shaft impact crusher is popular in the market for its significant advantages such as large ...

CONSTMACH Secondary Impact Crushers offer high capacity, cubic shape and reduced wear costs. Besides having the greatest durability, our ease of maintenance means less total downtime. Thanks to their ...

Product introduction The PYY series single-cylinder hydraulic cone crusher is suitable for large and medium-sized sand and ore processing enterprises .It's used as a secondary, tertiary or fourth-grade ...

Product introduction PF Series-Impact Crusher is featured with large crushing ratio, simple and reasonable structure, stable operation, simple maintenance, quick replacement and high crushing efficiency .It have been ...

... parts such as packing box crusher screws to rust and even break. If it is light, the blade screen may damage or injure the operator. Many people are very confused about whether there is any way to prevent the formation ...

... jaw crushers have proven to be reliable and productive in thousands of mining, quarrying, recycling and industrial applications with up to 11,000 jaw crusher installations since 1975. Developed to ...

... series cone crushers deliver a proven approach to processing primary, crushed ores and quarry rock products. These crushers are designed to be reliable, simple to operate and maintain, while incurring ...

Performance highlights Can be used in primairy, secondary, tertiary or quarternary crushing Designed to crush the toughest of rock and ore Feed size up to 185 mm (7) C.S.S min. - max. 6 - 38 mm (2/10-1 5/10), depending ...

... FLSmidth, that is exactly what you get. Throughout the world, ABON Low Speed Sizers have been commissioned in Primary, Secondary, Tertiary and Quaternary applications across the minerals range, with installation in ...

The Powerscreen 1000 Maxtrak is equipped with Automax cone crusher that serves strong cubidity for the production of aggregate and sub-base components. It is utilized in feed operations excluding the pre-screening on ...

... developed the new generation of high-efficiency coarse and medium-fine crushing machine CI5X Impact Crusher. This impact crusher is the ideal upgrading product of conventional crushing machines. Product ...

... and stationary knives, raw materials are crushed.Supplied water washes raw materials, cools knives and reduces noise of the crusher. Crushed raw materials pass through the grid hole and then get into the discharge hopper.

... primary and secondary impact crushers, which introduces a further crushing stage in the machine. Essentially, the grinding path limits the maximum grain size of the product and produces a product with ...

The EDGE RS1500 roll sizer has been designed for the secondary and tertiary crushing of medium-hard, sticky and soft materials such as coal, lignite, clay, limestone and other bituminous and sub-bituminous materials. Boasting ...

crushers - all crusher types for your reduction needs - metso outotec

crushers - all crusher types for your reduction needs - metso outotec

All rock crushers can be classified as falling into two main groups. Compressive crushers that press the material until it breaks, and impact crushers using the principle of quick impacts to crush the material. Jaw crushers, gyratory crushers, and cone operate according to the compression principle. Impact crushers, in turn, utilize the impact principle.

As the name suggest, jaw crushers reduce rock and other materials between a fixed and a moving jaw. The moving jaw is mounted on a pitman that has a reciprocating motion, and the fixed jaw stays put. When the material runs between the two jaws, the jaws compress larger boulders into smaller pieces.

There are two basic types of jaw crushers: single toggle and double toggle. In the single toggle jaw crusher, an eccentric shaft is on the top of the crusher. Shaft rotation causes, along with the toggle plate, a compressive action.

The chewing movement, which causes compression at both material intake and discharge, gives the single toggle jaw better capacity, compared to a double toggle jaw of similar size. Metsos jaw crushers are all single toggle.

Gyratory crushers have an oscillating shaft. The material is reduced in a crushing cavity, between an external fixed element (bowl liner) and an internal moving element (mantle) mounted on the oscillating shaft assembly.

The fragmentation of the material results from the continuous compression that takes place between the liners around the chamber. An additional crushing effect occurs between the compressed particles, resulting in less wear of the liners.

Cone crushers resemble gyratory crushers from technological standpoint, but unlike gyratory crushers, cone crushers are popular in secondary, tertiary, and quaternary crushing stages. Sometimes, however, the grain size of the processed material is small enough by nature and the traditional primary crushing stage is not needed. In these cases, also cone crushers can carry out the first stage of the crushing process.

Cone crushers have an oscillating shaft, and the material is crushed in a crushing cavity, between an external fixed element (bowl liner) and an internal moving element (mantle) mounted on the oscillating shaft assembly.

An eccentric shaft rotated by a gear and pinion produces the oscillating movement of the main shaft. The eccentricity causes the cone head to oscillate between open side setting and closed side setting discharge opening.

The fragmentation of the material results from the continuous compression that takes place between the liners around the chamber. An additional crushing effect occurs between the compressed particles, resulting in less wear of the liners. This is called interparticular crushing also.

Depending on cone crusher, setting can be adjusted in two ways. The first way is for setting adjustment to be done by rotating the bowl against the threads so that the vertical position of the outer wear part (concave) is changed. One advantage of this adjustment type is that liners wear more evenly.

To optimize operating costs and improve the product shape it is recommended that cone crushers are always be choke fed, meaning that the cavity should be as full of rock material as possible. This can be easily achieved by using a stockpile or a silo to regulate the inevitable fluctuation of feed material flow. Level monitoring devices detect the maximum and minimum levels of the material, starting and stopping the feed of material to the crusher, as needed.

Impact crushers are traditionally classified to two main types: horizontal shaft impact (HSI) crushers and vertical shaft impact (VSI) crushers. These different types of impact crushers share the crushing principle, impact, to reduce the material to smaller sizes, but features, capacities and optimal applications are far from each other.

Horizontal shaft impact (HSI) crushers are used in primary, secondary or tertiary crushing stage. HSI crushers reduce the feed material by highly intensive impacts originating in the quick rotational movement of hammers or bars fixed to the rotor. The particles produced are then further fragmentated inside the crusher as they collide against crusher chamber and each other, producing a finer, better-shaped product.

VSI crusher can be considered a stone pump that operates like a centrifugal pump. The material is fed through the center of the rotor, where it is accelerated to high speed before being discharged through openings in the rotor periphery. The material is crushed as it hits of the outer body at high speed and due to rocks colliding against each other.

Selecting optimal crushing equipment can be difficult. Luckily there are tools and software available that simplify weighting different options and help in making decisions. The backbone of all these analyzes are careful calculations that take into account the capabilities and constraints of different crushers and operational requirements.

Every crushing site and operation is different, and theoptimal results are normally obtained by combining theoretical conclusions with practical experience of different materials, operational conditions, maintenance needs, and economic aspects of various alternatives.

Below are some key issues listed according to crushing stages in brief. While defining the best technical solution for your requirements, its good to remember that many crushers are available not only as stationary but also asmobileorportableversions in case you prefer to move or transport your crusher at the production site or between sites regularly.

If you are interested in more detailed analyzes tailored just for your crushing operations, please contact Metso experts. We have practical experience of thousands of different crushing applications around the world, and we are happy to help in finding the equipment that best fits your needs.

The main purpose of a primary crusher is to reduce the material to a size that allows its transportation on a conveyor belt. In most crushing installations a jaw crusher takes care of primary crushing. Plants with very high capacities that are common in mining and less popular in aggregates production, normally use a primary gyratory crusher. When the processed material is easy to crush and not very abrasive, an impact crusher may be the best choice for primary crushing.

One of the most important characteristics of a primary crusher is its capacity for accepting feed material without bridging. A large primary crusher is, naturally, more expensive than a smaller one. Therefore, the investment cost calculations for primary crushers are compared together against the total costs of primary stages, including quarry face clearing, blasting, and drilling costs. In many cases, dump trucks transport the rock to a stationary primary crusher. This may be an expensive solution. Amortization, fuel, tires, and maintenance costs can be included when the vehicles are in high demand. In modern aggregates operations, the use of mobile primary crushers that can move alongside the rock face is, in many cases, the most economical solution.

In terms of the size of the feed opening, the client gets a better return on investment when the primary crusher is a jaw crusher. That means less drilling and blasting because the crusher accepts larger boulders. The disadvantage of this type of crusher, when high capacity is required, is the relatively small discharge width, limiting the capacity as compared with the discharge circuit of a gyratory crusher. Jaw crushers are mainly used in plants producing up to approximately 1600 t/h.

The primary gyratory crusher offers high capacity thanks to its generously dimensioned circular discharge opening (which provides a much larger area than that of the jaw crusher) and the continuous operation principle (while the reciprocating motion of the jaw crusher produces a batch crushing action). The gyratory crusher has no rival in large plants with capacities starting from 1200 t/h and above. To have a feed opening corresponding to that of a jaw crusher, the primary gyratory crusher must be much taller and heavier. Also, primary gyratories require quite a massive foundation.

The primary impact crusher offers high capacity and is designed to accept large feed sizes. The primary impact crushers are used to process from 200 t/h up to 1900 t/h and feed sizes of up to 1830 mm (71") in the largest model. Primary impact crushers are generally used in nonabrasive applications and where the production of fines is not a problem. Of all primary crushers, the impactor is the crusher that gives the best cubical product.

If the intermediate crushing is done with the purpose of producing railway ballast, the quality of the product is important. In other cases, there normally are no quality requirements, except that the product be suitable for fine crushing.

Due to their design, cone crushers are generally a more expensive investment than impactors are. However, when correctly used, a cone crusher offers lower operating costs than a conventional impact crusher. Therefore, clients crushing hard or abrasive materials are advised to install cone crushers for the final crushing and cubicising stage.

Cone crushers can in most cases also give a good cubic shape to fine grades. They can be adapted to different applications. This is an important factor, as client-specific needs often change during a crushers lifetime.

The conventional type has horizontal shaft configuration, known as HSI. The other type consists of a centrifugal crusher with vertical shaft, generally known as VSI. Impactor operation is based on the principle of rapid transfer of impact energy to the rock material. Impactors produce cubic products, and they can offer high reduction ratios as long as the feed material is not too fine. This means that in certain cases it is possible to use a single impact crusher to carry out a task normally done in several crushing stages using compressing crushers (i.e., jaw, gyratory, and/or cone crushers). Impactors are mostly used for nonabrasive materials.

Conventional horizontal-shaft impact crushers are available in various sizes and models, from high-capacity primary crushers for large limestone quarries to specially designed machines for the crushing of materials such as slag.

There are two main categories of VSI crushers machines with impact wear parts around the body and machines that use a layer of accumulated material. The first type is in many respects similar to the conventional impactor with horizontal shaft and rotor. The second type became quite popular in the past decade and is known as the Barmac crusher. The difference between a conventional impactor and a VSI of the Barmac type is that the latter offers lower operating costs, but its reduction ratio is lower also. In a Barmac VSI, the material undergoes an intense rock-on-rock crushing process. In the other crushers, most of the reduction is done by the impact of stone against metal.

Customers operating old, rebuilt, or expanded plants often have problems with the shape of the product. In these cases, the addition of a Barmac VSI in the final crushing stage offers a solution to product shape problems.

The same applies to many mobile crushing units. As the number of crushing stages is normally small with this type of plant, it is almost impossible to obtain a good product shape unless the rock is relatively soft and thus more suited for the production of cubic product. A centrifugal crusher in the final stage can help to solve the problem.

Get the maximum potential out of your size reduction process to achieve improved crushing performance and lower cost per ton. By using our unique simulation software, our Chamber Optimization experts can design an optimized crushing chamber that matches the exact conditions under which you operate.

crusher - an overview | sciencedirect topics

crusher - an overview | sciencedirect topics

Roll crushers are generally not used as primary crushers for hard ores. Even for softer ores, like chalcocite and chalcopyrite they have been used as secondary crushers. Choke feeding is not advisable as it tends to produce particles of irregular size. Both open and closed circuit crushing are employed. For close circuit the product is screened with a mesh size much less than the set.

Fig. 6.4 is a typical set up where ore crushed in primary and secondary crushers are further reduced in size by a rough roll crusher in open circuit followed by finer size reduction in a closed circuit by roll crusher. Such circuits are chosen as the feed size to standard roll crushers normally do not exceed 50mm.

Cone crushers were originally designed and developed by Symons around 1920 and therefore are often described as Symons cone crushers. As the mechanism of crushing in these crushers are similar to gyratory crushers their designs are similar, but in this case the spindle is supported at the bottom of the gyrating cone instead of being suspended as in larger gyratory crushers. Fig. 5.3 is a schematic diagram of a cone crusher. The breaking head gyrates inside an inverted truncated cone. These crushers are designed so that the head to depth ratio is larger than the standard gyratory crusher and the cone angles are much flatter and the slope of the mantle and the concaves are parallel to each other. The flatter cone angles helps to retain the particles longer between the crushing surfaces and therefore produce much finer particles. To prevent damage to the crushing surfaces, the concave or shell of the crushers are held in place by strong springs or hydraulics which yield to permit uncrushable tramp material to pass through.

The secondary crushers are designated as Standard cone crushers having stepped liners and tertiary Short Head cone crushers, which have smoother crushing faces and steeper cone angles of the breaking head. The approximate distance of the annular space at the discharge end designates the size of the cone crushers. A brief summary of the design characteristics is given in Table 5.4 for crusher operation in open circuit and closed circuit situations.

The Standard cone crushers are for normal use. The Short Head cone crushers are designed for tertiary or quaternary crushing where finer product is required. These crushers are invariably operated in closed circuit. The final product sizes are fine, medium or coarse depending on the closed set spacing, the configuration of the crushing chamber and classifier performance, which is always installed in parallel.

For finer product sizes, i.e. less than 6mm, special cone crushers known as Gyradisc crushers are available. The operation is similar to the standard cone crushers except that the size reduction is caused more by attrition than by impact, [5]. The reduction ratio is around 8:1 and as the product size is relatively small the feed size is limited to less than 50mm with a nip angle between 25 and 30. The Gyradisc crushers have head diameters from around 900-2100mm. These crushers are always operated in choke feed conditions. The feed size is less than 50mm and therefore the product size is usually less than 6-9mm.

Crushing is accomplished by compression of the ore against a rigid surface or by impact against a surface in a rigidly constrained motion path. Crushing is usually a dry process and carried out on ROM ore in succession of two or three stages, namely, by (1) primary, (2) secondary, and (3) tertiary crushers.

Primary crushers are heavy-duty rugged machines used to crush ROM ore of () 1.5m size. These large-sized ores are reduced at the primary crushing stage for an output product dimension of 1020cm. The common primary crushers are of jaw and gyratory types.

The jaw crusher reduces the size of large rocks by dropping them into a V-shaped mouth at the top of the crusher chamber. This is created between one fixed rigid jaw and a pivoting swing jaw set at acute angles to each other. Compression is created by forcing the rock against the stationary plate in the crushing chamber as shown in Fig.13.9. The opening at the bottom of the jaw plates is adjustable to the desired aperture for product size. The rocks remain in between the jaws until they are small enough to be set free through this opening for further size reduction by feeding to the secondary crusher.

The type of jaw crusher depends on input feed and output product size, rock/ore strength, volume of operation, cost, and other related parameters. Heavy-duty primary jaw crushers are installed underground for uniform size reduction before transferring the ore to the main centralized hoisting system. Medium-duty jaw crushers are useful in underground mines with low production (Fig.13.10) and in process plants. Small-sized jaw crushers (refer to Fig.7.32) are installed in laboratories for the preparation of representative samples for chemical analysis.

The gyratory crusher consists of a long, conical, hard steel crushing element suspended from the top. It rotates and sweeps out in a conical path within the round, hard, fixed crushing chamber (Fig.13.11). The maximum crushing action is created by closing the gap between the hard crushing surface attached to the spindle and the concave fixed liners mounted on the main frame of the crusher. The gap opens and closes by an eccentric drive on the bottom of the spindle that causes the central vertical spindle to gyrate.

The secondary crusher is mainly used to reclaim the primary crusher product. The crushed material, which is around 15cm in diameter obtained from the ore storage, is disposed as the final crusher product. The size is usually between 0.5 and 2cm in diameter so that it is suitable for grinding. Secondary crushers are comparatively lighter in weight and smaller in size. They generally operate with dry clean feed devoid of harmful elements like metal splinters, wood, clay, etc. separated during primary crushing. The common secondary crushers are cone, roll, and impact types.

The cone crusher (Fig.13.12) is very similar to the gyratory type, except that it has a much shorter spindle with a larger-diameter crushing surface relative to its vertical dimension. The spindle is not suspended as in the gyratory crusher. The eccentric motion of the inner crushing cone is similar to that of the gyratory crusher.

The roll crusher consists of a pair of horizontal cylindrical manganese steel spring rolls (Fig.13.14), which rotate in opposite directions. The falling feed material is squeezed and crushed between the rollers. The final product passes through the discharge point. This type of crusher is used in secondary or tertiary crushing applications. Advanced roll crushers are designed with one rotating cylinder that rotates toward a fix plate or rollers with differing diameters and speeds. It improves the liberation of minerals in the crushed product. Roll crushers are very often used in limestone, coal, phosphate, chalk, and other friable soft ores.

The impact crusher (Fig.13.15) employs high-speed impact or sharp blows to the free-falling feed rather than compression or abrasion. It utilizes hinged or fixed heavy metal hammers (hammer mill) or bars attached to the edges of horizontal rotating discs. The hammers, bars, and discs are made of manganese steel or cast iron containing chromium carbide. The hammers repeatedly strike the material to be crushed against a rugged solid surface of the crushing chamber breaking the particles to uniform size. The final fine products drop down through the discharge grate, while the oversized particles are swept around for another crushing cycle until they are fine enough to fall through the discharge gate. Impact crushers are widely used in stone quarrying industry for making chips as road and building material. These crushers are normally employed for secondary or tertiary crushing.

If size reduction is not completed after secondary crushing because of extra-hard ore or in special cases where it is important to minimize the production of fines, tertiary recrushing is recommended using secondary crushers in a close circuit. The screen overflow of the secondary crusher is collected in a bin (Fig.13.16) and transferred to the tertiary crusher through a conveyer belt in close circuit.

Primary jaw crushers typically operate in open circuit under dry conditions. Depending on the size reduction required, the primary jaw crushers are followed by secondary and tertiary crushing. The last crusher in the line of operation operates in closed circuit. That is, the crushed product is screened and the oversize returned to the crusher for further size reduction while the undersize is accepted as the product. Flow sheets showing two such set-ups are shown in Figs. 3.1 and 3.2.

Jaw crushers are installed underground in mines as well as on the surface. When used underground, jaw crushers are commonly used in open circuit. This is followed by further size reduction in crushers located on the surface.

When the run of mine product is conveyed directly from the mine to the crusher, the feed to the primary crusher passes under a magnet to remove tramp steel collected during the mining operation. A grizzly screen is placed between the magnet and the receiving hopper of the crusher to scalp (remove) boulders larger than the size of the gape. Some mines deliver product direct to storage bins or stockpiles, which then feed the crushers mechanically by apron feeders, Ross feeders or similar devices to regulate the feed rate to the crusher. Alternately haulage trucks, front-end loaders, bottom discharge railroad cars or tipping wagons are used. In such cases, the feed rate to the crusher is intermittent which is a situation generally avoided. In such cases of intermittent feed, storage areas are installed and the feed rate regulated by bulldozers, front loaders or bin or stockpile hoppers and feeders. It is necessary that the feed to jaw crushers be carefully designed to balance with the throughput rate of the crusher. When the feed rate is regulated to keep the receiving hopper of the crusher full at all times so that the volume rate of rock entering any point in the crusher is greater than the rate of rock leaving, it is referred to as choke feeding. During choke feeding the crushing action takes place between the jaw plates and particles as well as by inter-particle compression. Choke feeding necessarily produces more fines and requires careful feed control. For mineral liberation, choked feeding is desirable.

When installed above ground, the object of the crushing circuit is to crush the ore to achieve the required size for down stream use. In some industries, for example, iron ore or coal, where a specific product size is required (iron ore 30+6mm), careful choice of jaw settings and screen sizes are required to produce the minimum amount of fines (i.e. 6mm) and maximum the amount of lump ore within the specified size range. For hard mineral bearing rocks like gold or nickel ores where liberation of minerals from the host rock is the main objective, further stages of size reduction are required.

A gold ore was crushed in a secondary crusher and screened dry on an 1180micron square aperture screen. The screen was constructed with 0.12mm diameter uniform stainless steel wire. The size analysis of the feed, oversize and undersize streams are given in the following table. The gold content in the feed, undersize and oversize streams were; 5ppm, 1.5ppm and 7ppm respectively. Calculate:

The self tuning control algorithm has been developed and applied on crusher circuits and flotation circuits [22-24] where PID controllers seem to be less effective due to immeasurable change in parameters like the hardness of the ore and wear in crusher linings. STC is applicable to non-linear time varying systems. It however permits the inclusion of feed forward compensation when a disturbance can be measured at different times. The STC control system is therefore attractive. The basis of the system is:

The disadvantage of the set up is that it is not very stable and therefore in the control model a balance has to be selected between stability and performance. A control law is adopted. It includes a cost function CF, and penalty on control action. The control law has been defined as:

A block diagram showing the self tuning set-up is illustrated in Fig. 18.27. The disadvantage of STC controllers is that they are less stable and therefore in its application a balance has to be derived between stability and performance.

Bone recycling is a simple process where useful products can be extracted. Minerals such as calcium powder for animal; feed are extracted from the bone itself. The base material for cosmetics and some detergent manufacturing needs are extracted from the bone marrow.

The bone recycling process passes through seven stages starting from crushing and ending with packing. Figure 13.14 gives a schematic diagram showing the bone recycling process which goes through the following steps:

Following the standard procedures in the Beijing SHRIMP Center, zircons were separated using a jaw crusher, disc mill, panning, and a magnetic separator, followed by handpicking using a binocular microscope. The grains were mounted together with the standard zircon TEM (417Ma, Black etal., 2003) and then polished to expose the internal structure of the zircons. Cathodoluminescence (CL) imaging was conducted using a Hitachi SEM S-3000N equipped with a Gatan Chroma CL detector in the Beijing SHRIMP Center. The zircon analysis was performed using the SHRIMP II also in the Beijing SHRIMP Centre. The analytical procedures and conditions were similar to those described by Williams (1998). Analytical spots with 25m diameter were bombarded by a 3nA, 10kV O2 primary ion beam to sputter secondary ions. Five scans were performed on every analysis, and the mass resolution was 5000 (at 1%). M257 standard zircon (561.3Ma, U=840ppm) was used as the reference value for the U concentration, and TEM standard zircons were used for Pb/U ratio correction (Black etal., 2003). Common Pb was corrected using the measured 204Pb. Data processing was performed using the SQUID/Isoplot programs (Ludwig, 2001a,b). Errors for individual analyses are at 1, but the errors for weighted average ages are at 2.

A stockpile can be used to blend ore from different sources. This is useful for flotation circuits where fluctuations ingrade can change the mass balance and circulating loads around the plant. Blending can also be done on the ROMpad.

The lowest cost alternative is to have no surge at all, but rather to have a crushing plant on line. This is workable for small-scale plant with single-stage jaw crushers as the availability of these simple plant is very high provided control over ROM size is maintained.

The second alternative is to use a small live surge bin after the primary crusher with a secondary reclaim feeder. Crushed ore feeds this bin continuously and the bin overflows to a small conveyor feeding a dead stockpile. In the event of a primary crusher failure, the crusher loader is used to reclaim the stockpile via the surge bin, which doubles as an emergency hopper.

For coarse ore, the next alternative is a coarse ore stockpile. Stockpiles of this type are generally 1525% live and require a tunnel (concrete or Armco) and a number of reclaim feeders to feed the milling circuit.

Multi-stage crushing circuits usually require surge capacity as the availability of each unit process is cumulative. A fine-ore bin is usually required. Smaller bins are usually fabricated from steel as this is cheaper. Live capacity of bins is higher than stockpiles but they also require a reclaim tunnel and feeders.

different types of crushing equipments - constro facilitator

different types of crushing equipments - constro facilitator

Crushers are mainly used for crushing stones or mineral ores, recycling construction waste, and producing aggregate. This equipment aims to reduce large solid raw material masses into smaller sizes. They also help to change waste material form so that they can be simply disposed of or recycled. They can also be used for secondary and tertiary crushing to produce the finished product and crushing materials between two parallel solid surfaces.

In an ever-changing industry, waste is one of the major issues for companies when it comes to maximising profits and winning tenders. With the proper application of crushing materials can be reused in other areas of industrial applications.

The primary crusher is only for the breaking of large stones into pieces (this means primary crusher is not for the aggregate size material.). Examples of primary crushers are jaw crusher; hammer mill crusher and gyratory crusher. After receiving the primary crusher crush the material and produce a new fresh reduced size of the source material. The primary crusher has only functioned up to that point. A secondary crusher comes into action and further reduces the size. In secondary crushers some sizes of stones may pass directly from sieve number At the end tertiary crusher reduces the size of crushed pieces very much to the required size and it also brings the fineness to the crushed material. Tertiary crushers are at the job site and these are small in size.

A Jaw Crusher is one of the main types of primary crushers in a mine or ore processing plant. The size of a jaw crusher is designated by the rectangular or square opening at the top of the jaws. Primary jaw crushers are typical of the square opening design, and secondary jaw crushers are of the rectangular opening design. A Jaw Crusher reduces large size rocks or ore by placing the rock into compression. A fixed jaw, mounted in a V alignment is the stationary breaking surface, while the movable jaw exerts a force on the rock by forcing it against the stationary plate. Due to their smaller physical size, jaw crushers are also ideal for tight spaces, such as underground mining and mobile crushing applications.

Newer jaw crusher models are more focused on safety and easy maintenance. Hydraulic separation and individual lifting of shells are in a trend that creates a better environment for any workers on-site working with the equipment

An impact crusher is a machine that uses striking as opposed to pressure to reduce the size of a material. Impact crushers are designated as a primary, secondary, tertiary or quaternary rotor crusher depending on which processing stage the equipment is being utilized. Impact Crushers may be used as primary, secondary, or tertiary crushers depending on the Producers final-product-size needs. Impact Crushers are available in stationary, track, and portable configurations meeting any demand for any of these industries. Although Impact Crushers generally have a higher operating cost than other crushers, they tend to produce a more uniform particle shape (cubical) which is desirable and produces more fines for hot asphalt producers. Common types of Impact Crushers are Horizontal Shaft Impactor (HSI) and Vertical Shaft Impactor (VSI).

The new hybrid models of impact crusher are engineered for maximum feed size, target output size, and total capacity. The newer models are capable of producing construction-grade aggregate, artificial sand and stone materials, run of mine material, especially for the secondary and tertiary crushing stages.

Gyratory crushers are principally used in surface-crushing plants. The gyratory crusher consists essentially of a long spindle, carrying a hard steel conical grinding element, the head, seated in an eccentric sleeve. The spindle is suspended from a spider and, as it rotates, normally between 85 and 150 rpm, it sweeps out a conical path within the fixed crushing chamber, or shell, due to the gyratory action of the eccentric. Gyratory crushers provide high throughput and less downtime to bring maximum efficiency to your operation.

The new primary gyratory crushers have new advancements that bring increased speeds, higher installed power and mechanical improvements. All of these combine to bring additional throughput for your primary gyratory crusher.

A Cone Crusher is a compression type of machine that reduces material by squeezing or compressing the feed material between a moving piece of steel and a stationary piece of steel. The crushed material is discharged at the bottom of the machine after they pass through the cavity. Cone crushers are popular rock crushing machines in aggregate production, mining operations, and recycling applications. They are normally used in secondary, tertiary, and quaternary crushing stages.

The new hybrid models of cone crusher come with multi-cylinder hydraulic cone systems suited for the secondary or tertiary stages of crushing plants by changing body liners and adaptors. It comes with the automatic control and fingertip manipulation system and two hydraulic cylinders that have a protective effect that if one overloads, then another one can fast react to clear choke merely by remote control.

Stationary hybrid crushers combine the advantages of different roll crusher systems and are an ideal solution for primary, secondary and tertiary crushing applications. They have specially designed teeth, hydraulic gap adjustment, overload protection, and a scraper system perfect for dealing with sticky materials. These machines can work at capacities of up to 12,000 metric tons per hour, enabling you to keep productivity high whilst producing high-quality output.

The newer models have a compact design and take up minimal space. The crushing rolls are equipped either with crushing rings, segments, or crushing picks, depending on the application and feed material. The drive system for the rolls consists of individual electric motors for each roll, as well as couplings and gears. Standard components are used for cost-effectiveness and simpler maintenance.

The overall range of capacity for mobile impact crushers is roughly about 100 to 500 tons per hour. Todays mobile impact crushers are especially ideal for smaller-scale recycling operations, for on-site recycling, and tight-space urban and roadside applications. These units are transportable by trailer, simply driven off at the location of the material that needs to be processed, and go to work very quickly. With their capability to produce accurately-sized, cubical-shaped end-product, mobile impact crushers work well as stand-alone plants, or they can add significant productivity to any operation, working in tandem with a jaw crusher or screen plant.

The newer models use a direct drive system for optimum fuel efficiency and low operating costs and include several user-friendly features. This ensures that theyre both simple to operate, and easy to maintain.

This is a type of secondary or reduction crusher consisting of a heavy frame on which two rolls are mounted. These are driven so that they rotate toward one another. Rock fed in from above is nipped between the moving rolls, crushed, and discharged at the bottom.

The newer models offer belt-driven Roll Crushers in four designs: Single Roll, Double Roll, Triple Roll and Quad Roll Crushers, which provide a substantial return on investment by operating at low cost and maximizing yield by generating minimal fines. The rugged design, which incorporates a fabricated steel base frame lined with replaceable abrasion-resistant steel liners, stands up to the toughest mineral processing applications while providing safe and simple operation, including an automatic tramp relief system to allow uncrushable objects to pass while the crusher remains in operation.

The newer models of this machine generate high-quality aggregates, cubical in shape, with superior soundness. Available in three sizes, the HammerMaster is known for making excellent asphalt chip material, concrete stone, and general base material and road rock. This mill is also capable of making agricultural lime for pH control in farm fields.

Rod mills run along with the outside gear. Materials spirally and evenly enter the crushing chamber along the input hollow axis by input devices. Steel rods of different specifications are installed in the crushing chamber. When the frame rotates, centrifugal force is produced. At the same time, the steel rods are carried to some height and then fall to grind and strike the material. After grinded in the crushing chamber, the powder is discharged by an output material board.

The newer models of this machine are driven by motor with speed reducer and peripheral large gear, or low-speed synchronous motor with peripheral large gear. The grinding medium steel rod is put into the cylinder which is lifted, and then falls under the action of the centrifugal force and friction force. The materials entering into the cylinder from the feeding inlet are grinded by movable grinding medium and discharged out by overflow and continuously feeding.

A ball mill is a type of grinder used to grind, blend and sometimes for mixing of materials for use in mineral dressing processes, paints, pyrotechnics, ceramics and selective laser sintering. It works on the principle of impact and attrition: size reduction is done by impact as the balls drop from near the top of the shell. The newer models of this machine are widely used in cement, silicate products, new building materials, refractory materials, fertilizer, black and non-ferrous metals and glass ceramics and other production industries of all kinds of ores and other grind-able materials can be dry or wet grinding.

Manufacturers offering crushing equipment have expanded their respective ranges, offering additional capabilities for these segments. Mobility and versatility have been key factors in the development of new models, with many firms also offering new options in the shape of electric and hybrid drive systems.

primary crusher selection & design

primary crusher selection & design

The crusher capacities given by manufacturers are typically in tons of 2,000 lbs. and are based on crushing limestone weighing loose about 2,700 lbs. per yard3 and having a specific gravity of 2.6. Wet, sticky and extremely hard or tough feeds will tend to reduce crusher capacities.

Selectiingwhat size a crusher needs to be is based on factors such as the F80 size of the rocks to be crushed, the production rate, and the P80 desired product output size. Primary crushers with crush run-of-mine rock from blast product size to what can be carried by the discharge conveyor or fit/math the downstream process.A typical example of primary crushing is reducing top-size from 900 to 200 mm.

Ultimately, the mining sequence will certainly impact the primary crusher selection. Where you will mine ore and where from, is a deciding factor not so much for picking between a jaw or gyratory crusher but its mobility level.

The mom and dad of primary crushers are jaw and gyratory crushers. In open-pit mines where high tonnage is required, thegyratory crushers are typically the choice as jaw crushers will not crush over 500 TPH with great ease. There are exceptions like MPI Mineral Park in AZ where 50,000 TPD was processed via 2 early century vintage jaw crushers of a:

The rated capacity at 5 closed-side setting was 490 stph based on standard 100lbs/ft3 feed material. These crushers were fed a very fine ore over a 4 grizzly which allowed the 1000 TPH the SAG mills needed.

In under-ground crushing plants where the diameter of the mine-shaft a skip forces limits on rock size, a jaw crusher will be the machine of choice. Again, if crushing on surface, both styles of stone crushing machines should be evaluated.

jaw crusher | primary crusher in mining & aggregate - jxsc mine

jaw crusher | primary crusher in mining & aggregate - jxsc mine

Product Introduction JXSC jaw type rock crusher is usually used as a primary crusher and secondary crusher to reduce the size of medium-hard materials to smaller physical size. Jaw rock crushers are capable of working with the mobile crushing station, underground crushing because of its related small volume. Capacity: 1-1120TPH Max Feeding Size: 120-1200mm Application Mining, metallurgy, building materials, quarrying, gravel & sand making, aggregate processing, recycling, road and railway construction and chemical industry, etc. Suitable Material Granite, marble,basalt, limestone, coal, quartz, pebble, iron ore, copper ore, etc.

40 years of manufacturing and engineering experience keep us innovative and knowledge in the rock break machines and its applications, which thus provide reliable industry rocks crushers and solutions for every customer using jaw crusher manufacturers JXSC machines to meet their production goals. The jaw crusher machine family consists of different sized models that are designed to bring maximum output with minimum cost. Some workplaces have limited conditions and are unable to provide electricity or are underpowered. According to these conditions, JXSC specially designed diesel jaw crusher. The diesel-jaw crusher is actually with electric, but the original jaw crusher was added with a diesel engine equipment that a dual-purpose crusher.

JXSC the crushers machine with a non-welded frame has been proved that it has outstanding solid and durable strength. All the alloy casting frame components turn out that with premium quality, wear-resistant property.

The design of pitman and long stoke improves productivity and reduction. A wider feeding material opening increases the volume of insulating material and makes the ore material entering the crushers crushing chamber smoothly. A sharp angle makes the materials flow down speed faster and reduces the wear cost. Besides, the strike force could be stronger thus increase the production efficiency as well as the reduction ratio.

Types of jaw crushers: on the basis of the stone break equipment size and capacity can divide into a heavy and small(mini) portable jaw rock crushers. According to the working principle can be split into single toggle and double toggle jaw rock crushers machine.

A series of jaw stone crushers use compressive and squeezing force for reducing materials. This physical force is created by the two jaw plates, one of which is a movable plate and another is fixed, both of them are made of manganese. A V-shaped cavity, crushing chamber, is formed and the hydraulic discharge gap width of the crushing chamber, we can determine the suited feeding material size and discharging size, the width of top feeding is larger than that of bottom discharging.

Jaw crusher is a heavy-duty machine that crushes hard materials. So its hence muse be robustly constructed. Crusher frame is made from steel or cast iron. The jaws are made of cast steel. The liners are made fromNi-hard, Ni-Cr alloyed cast iron or manganese steel which can replaceable and use to reduce frame wear. The cheek plates are also made from hard alloy steel and installed to the sides of the crushing chamber to protect the frame from wear.

The jaws can be made in smooth or corrugated, but often corrugated. Because the latter crushing the hard and abrasive ores is better. The angle between the jaws is usually less than 26. This is because a large angle will cause the particle to slip which non-crush.

It uses curved plates to avoid the near the discharge of jaw crusher blocking. The bottom of the swinging jaw is concave, and the relative lower part of the fixed jaw is convex. The materials reduction in size when nears the exit. So the material is distributed over a larger area, and the jaws plates wear less.

The type of crushed materials determines how to design the max amplitude of swing of the jaw and the amplitude adjusted by changing the eccentric. The length from 1 to 7 cm depends on the crusher machine size. Jaw crushers are supplied in sizes up to 1,600 mm (gape)1,900 mm (width). For coarse crushing application (closed set~300 mm), capacities range up to 1200 tph.

Jaw crusher parts must have some wear after a period of use, but the easily damaged parts will wear out more. The price of crushing equipment with the same specifications and handling capacity is different in the material of parts.

Guard Plate The guard plate is made of high-quality high manganese steel, which is located between the fixed plate and the movable plate. The whole body is mainly to protect the jaw crusher frame wall.

Toothed Plate Tooth plate is divided into movable and fixed tooth plate, but both is made from high manganese steel casting. In order to prolong its service life, its shape is designed to be symmetrical. That is when one end of the wear can be used to turn the head. The movable and the fixed teeth plate are the main parts for stone crushing. So the movable teeth plate is installed on the movable jaw to protect the movable jaw.

Toggle Plate The toggle plate is a cast iron piece that has been precisely calculated. It is not only a force transmission component but also the safety parts of the crusher. When the crusher falls into the non-crushing material and makes the machine beyond the normal load, the toggle plate will immediately break. Then the crusher machine stops operation, thus avoiding the damage of the whole machine. The toggle plate and the toggle plate spacer adopt the rolling contact model which less attrition under normal use. It just needs smear a layer of grease on the contact surface is ok.

Triangular Belt When the motor transmits power, the triangle belt is connected with the pulley and the grooved pulley of the motor to drive the eccentric shaft and make the moving jaw move back and forth according to the predetermined track.

The tooth plate of the most jaw crushers are made of manganese steel, bearing linings are made of babbitt alloy, sliding blocks are made of carbon steel, toggle plates are made of cast iron, springs are made of 60SiMn. Regular Inspection and maintenance of the machine can extend its service life. In order to reduce customer costs, we will generally be in the purchase of customers are advised to buy some spare parts. Because once the parts need to be replaced, the temporary purchase will take some time. The wait time may cause the entire breakage line to suspend operations, thereby increasing operating costs.

In short, the jaw stone crushers are mainly used for primary crusher, the crushing stone is relatively large. The types of crusher machine's chamber are deep and no dead zone. It improves that the feeding capacity and output. The crushing ratio is large and the product particle size is even. Shim type outlet adjustment device, reliable and convenient, large hydraulic adjustment range that increased the flexibility of the equipment. Simple structure, reliable work and low operation cost. The adjustment range of hydraulic discharge opening is large, which can meet the requirements of different users, low noise and less dust.

Impact crusher for crushing medium-hard stones, and mostly used for secondary crusher. The impact crushers have a big feeding port, high crushing cavity, high material hardness, big block size and little stone powder. Convenient maintenance, economic and reliable, high comprehensive benefit.

Jiangxi Shicheng stone crusher manufacturer is a new and high-tech factory specialized in R&D and manufacturing crushing lines, beneficial equipment,sand-making machinery and grinding plants. Read More

primary & secondary ddc-sizers | mclanahan

primary & secondary ddc-sizers | mclanahan

McLanahan DDC-Sizers are direct drive crusher-sizers that are used in the primary and secondary reduction of friable, low-silica minerals. Used in both surface and underground mining operations, our Sizers can reduce materials such as coal, salt, gypsum, phosphate, limestone, bauxite, petroleum coke, lignite, trona, carbon anodes, oil sands, clay, shale and similar friable minerals.

The direct drive arrangement and low-profile design of DDC-Sizers is ideal for movable configurations, such as wheel-mounting for a movable configuration. The preferred method of installation is to mount the unit on rails with a non-rigid connection between the feed and discharge chutes. Because the drives are attached to the mainframe of the sizer, it is possible to roll the entire unit out from under the hopper or material stream when maintenance is required.

With DDC-Sizers installed and operating around the world, McLanahan is one of the world's most experienced manufacturers in the design and production of sizers. These sizers are designed and manufactured to improve the total cost of ownership over the life of your machine by being more efficient and easy to maintain. McLanahan provides lifetime service and support of DDC-Sizers and uses standard, readily available motors, gearboxes and couplings. All segments and sizing combs in McLanahan DDC-Sizers are designed to be interchangeable throughout the machine.

Primary and Secondary DDC-Sizers feature a unique hydraulic product size adjustment, which allows producers versatility if the product size requirements change. This feature allows producers not only the option of maintaining original size specifications, but also gives them the ability to adjust to meet changes in product size requirements. The hydraulic adjustable roll also allows producers to maintain product specifications when compensating for tooth wear.

DDC-Sizers are sized and selected based on the specific material and lump size to be crushed. Tooth profile selection allows the material to be grabbed and pulled into the crushing zone for maximum efficiency.

DDC-Sizers use an electric motor to drive the gear reducer, which is mounted directly to the crushing shaft. The motor is protected via a fluid coupling fitted with a thermal element to eliminate the risk of shock loads or stall events transferring through to the motor. Inward rotating rolls on primary and secondary sizers allow under-sized feed material to flow around the crushing zone and backside of the inward rotating rolls. The intermeshing sizing combs prevent any oversized material from passing through. This creates a screening effect and minimizes additional fines generation, which can be created through inter-particle crushing.

DDC-Sizers have a direct drive arrangement and low-profile design that allows wheel mounting for a movable configuration. The preferred method of installation is to mount the unit on rails with a non-rigid connection between the feed and discharge chutes. Since the drives are attached to the mainframe of the sizer, the entire unit can be rolled out from the feed stream to facilitate maintenance. McLanahan DDC-Sizers are equipped with hydraulic lift cylinders for ease of wheel activation.

DDC-Sizers have long been used in a variety of applications, including ROM feeds, coal, salt, gypsum, phosphate, limestone, bauxite, petroleum coke, lignite, trona, carbon anodes, oil sands, clay, shale and other friable minerals.

If your DDC-Sizer is operating with worn teeth, its throughput capacity will be reduced. To keep your crusher operating at maximum efficiency, monitor the height of the teeth by comparing them to the original as supplied tooth height and applying hardface welding where needed to build up the teeth.

Controlling the flow of feed material into a sizer guarantees an even distribution along the full length of the rolls and an even feed split between the rolls. This ensures even wear of both rolls, as well as even wear along the length the rolls. This helps to maximize wear part life and throughput capacity of the sizer.

Check the Lubrication Section of the Installation, Operation and Maintenance Manual for the specific quantity, but you want to be sure you are adding enough new grease to remove all the used grease from the seal.

To change the oil on the gearbox, first remove the top inspection cover. Inspect the internal components for damage, debris or wear. Remove the desiccant filter/breather and replace it with a new one. Fill the gear reducer until it reaches the fill level on the sight glass.

Designed with a direct drive arrangement that result in low-profile machines that minimize capital installation costs and allow for a movable configuration, McLanahan DDC-Sizers provide primary, secondary and tertiary reduction of friable, low silica materials. They incorporate two rolls with teeth that rotate either toward or away from each other at lower speeds in order to minimize fines generation and overall plant operating costs. McLanahan offers many different roll designs, tooth configurations and material selections that are engineered to maximize a sizers efficiency and wear life and to minimize the cost of ownership. Unique to McLanahan primary and secondary DDC-Sizers is the hydraulic product size adjustment, which allows producers versatility if the product size requirements change, and tertiary DDC-Sizers offer adjustability through the use of adjustable sizing combs.

gyratory crusher - an overview | sciencedirect topics

gyratory crusher - an overview | sciencedirect topics

Gyratory crushers were invented by Charles Brown in 1877 and developed by Gates around 1881 and were referred to as a Gates crusher [1]. The smaller form is described as a cone crusher. The larger crushers are normally known as primary crushers as they are designed to receive run-on-mine (ROM) rocks directly from the mines. The gyratory crushers crush to reduce the size by a maximum of about one-tenth its size. Usually, metallurgical operations require greater size reduction; hence, the products from the primary crushers are conveyed to secondary or cone crushers where further reduction in size takes place. Here, the maximum reduction ratio is about 8:1. In some cases, installation of a tertiary crusher is required where the maximum reduction is about 10:1. The secondary crushers are also designed on the principle of gyratory crushing, but the construction details vary.

Similar to jaw crushers, the mechanism of size reduction in gyratory crushers is primarily by the compressive action of two pieces of steel against the rock. As the distance between the two plates decreases continuous size reduction takes place. Gyratory crushers tolerate a variety of shapes of feed particles, including slabby rock, which are not readily accepted in jaw crushers because of the shape of the feed opening.

The gyratory crusher shown in Figure 2.6 employs a crushing head, in the form of a truncated cone, mounted on a shaft, the upper end of which is held in a flexible bearing, whilst the lower end is driven eccentrically so as to describe a circle. The crushing action takes place round the whole of the cone and, since the maximum movement is at the bottom, the characteristics of the machine are similar to those of the Stag crusher. As the crusher is continuous in action, the fluctuations in the stresses are smaller than in jaw crushers and the power consumption is lower. This unit has a large capacity per unit area of grinding surface, particularly if it is used to produce a small size reduction. It does not, however, take such a large size of feed as a jaw crusher, although it gives a rather finer and more uniform product. Because the capital cost is high, the crusher is suitable only where large quantities of material are to be handled.

However, the gyratory crusher is sensitive to jamming if it is fed with a sticky or moist product loaded with fines. This inconvenience is less sensitive with a single-effect jaw crusher because mutual sliding of grinding surfaces promotes the release of a product that adheres to surfaces.

The profile of active surfaces could be curved and studied as a function of the product in a way to allow for work performed at a constant volume and, as a result, a higher reduction ratio that could reach 20. Inversely, at a given reduction ratio, effective streamlining could increase the capacity by 30%.

Maintenance of the wear components in both gyratory and cone crushers is one of the major operating costs. Wear monitoring is possible using a Faro Arm (Figure 6.10), which is a portable coordinate measurement machine. Ultrasonic profiling is also used. A more advanced system using a laser scanner tool to profile the mantle and concave produces a 3D image of the crushing chamber (Erikson, 2014). Some of the benefits of the liner profiling systems include: improved prediction of mantle and concave liner replacement; identifying asymmetric and high wear areas; measurement of open and closed side settings; and quantifying wear life with competing liner alloys.

Crushers are widely used as a primary stage to produce the particulate product finer than about 50100mm. They are classified as jaw, gyratory, and cone crushers based on compression, cutter mill based on shear, and hammer crusher based on impact.

A jaw crusher consists essentially of two crushing plates, inclined to each other forming a horizontal opening by their lower borders. Material is crushed between a fixed and a movable plate by reciprocating pressure until the crushed product becomes small enough to pass through the gap between the crushing plates. Jaw crushers find a wide application for brittle materials. For example, they are used for comminution of porous copper cake. A Fritsch jaw crusher with maximal feed size 95mm, final fineness (depends on gap setting) 0.315mm, and maximal continuous throughput 250Kg/h is shown in Fig. 2.8.

A gyratory crusher includes a solid cone set on a revolving shaft and placed within a hollow body, which has conical or vertical sloping sides. Material is crushed when the crushing surfaces approach each other and the crushed products fall through the discharging opening.

Hammer crushers are used either as a one-step primary crusher or as a secondary crusher for products from a primary crusher. They are widely used for crushing hard metal scrap for different hard metal recycling processes. Pivoted hammers are pendulous, mounted on the horizontal axes symmetrically located along the perimeter of a rotor. Crushing takes place by the impact of material pieces with the high speed moving hammers and by contact with breaker plates. A cylindrical grating or screen is placed beneath the rotor. Materials are reduced to a size small enough to pass through the openings of the grating or screen. The size of the product can be regulated by changing the spacing of the grate bars or the opening of the screen.

The feature of the hammer crushers is the appearance of elevated pressure of air in the discharging unit of the crusher and underpressure in the zone around the shaft close to the inside surface of the body side walls. Thus, the hammer crushers also act as high-pressure, forced-draught fans. This may lead to environmental pollution and product losses in fine powder fractions. A design for a hammer crusher (Fig. 2.9) essentially allows a decrease of the elevated pressure of air in the crusher discharging unit [5]. The A-zone beneath the screen is communicated through the hollow ribs and openings in the body side walls with the B-zone around the shaft close to the inside surface of body side walls. As a result, the circulation of suspended matter in the gas between A and B zones is established and the high pressure of air in the discharging unit of crusher is reduced.

Crushers are widely used as a primary stage to produce the particulate product finer than about 50100 mm in size. They are classified as jaw, gyratory and cone crushers based on compression, cutter mill based on shear and hammer crusher based on impact.

A jaw crusher consists essentially of two crushing plates, inclined to each other forming a horizontal opening by their lower borders. Material is crushed between a fixed and a movable plate by reciprocating pressure until the crushed product becomes small enough to pass through the gap between the crushing plates. Jaw crushers find a wide application for brittle materials. For example, they are used for comminution of porous copper cake.

A gyratory crusher includes a solid cone set on a revolving shaft and placed within a hollow body, which has conical or vertical sloping sides. Material is crushed when the crushing surfaces approach each other and the crushed products fall through the discharging opening.

Hammer crushers are used either as a one-step primary crusher or as a secondary crusher for products from a primary crusher. They are widely used for crushing of hard metal scrap for different hard metal recycling processes.

Pivoted hammers are pendulous, mounted on the horizontal axes symmetrically located along the perimeter of a rotor and crushing takes place by the impact of material pieces with the high speed moving hammers and by contact with breaker plates. A cylindrical grating or screen is placed beneath the rotor. Materials are reduced to a size small enough pass through the openings of the grating or screen. The size of product can be regulated by changing the spacing of the grate bars or the opening of the screen.

The feature of the hammer crushers is the appearance of elevated pressure of air in the discharging unit of the crusher and underpressure in the zone around of the shaft close to the inside surface of the body side walls. Thus, the hammer crushers also act as high-pressure forced-draught fans. This may lead to environmental pollution and product losses in fine powder fractions.

A design for a hammer crusher (Figure 2.6) allows essentially a decrease of the elevated pressure of air in the crusher discharging unit [5]. The A-zone beneath the screen is communicated through the hollow ribs and openings in the body side walls with the B-zone around the shaft close to the inside surface of body side walls. As a result, circulation of suspended matter in the gas between A- and B-zones is established and high pressure of air in the discharging unit of crusher is reduced.

Jaw crushers are mainly used as primary crushers to produce material that can be transported by belt conveyors to the next crushing stages. The crushing process takes place between a fixed jaw and a moving jaw. The moving jaw dies are mounted on a pitman that has a reciprocating motion. The jaw dies must be replaced regularly due to wear. Figure 8.1 shows two basic types of jaw crushers: single toggle and double toggle. In the single toggle jaw crusher, an eccentric shaft is installed on the top of the crusher. Shaft rotation causes, along with the toggle plate, a compressive action of the moving jaw. A double toggle crusher has, basically, two shafts and two toggle plates. The first shaft is a pivoting shaft on the top of the crusher, while the other is an eccentric shaft that drives both toggle plates. The moving jaw has a pure reciprocating motion toward the fixed jaw. The crushing force is doubled compared to single toggle crushers and it can crush very hard ores. The jaw crusher is reliable and robust and therefore quite popular in primary crushing plants. The capacity of jaw crushers is limited, so they are typically used for small or medium projects up to approximately 1600t/h. Vibrating screens are often placed ahead of the jaw crushers to remove undersize material, or scalp the feed, and thereby increase the capacity of the primary crushing operation.

Both cone and gyratory crushers, as shown in Figure 8.2, have an oscillating shaft. The material is crushed in a crushing cavity, between an external fixed element (bowl liner) and an internal moving element (mantle) mounted on the oscillating shaft assembly. An eccentric shaft rotated by a gear and pinion produces the oscillating movement of the main shaft. The eccentricity causes the cone head to oscillate between the open side setting (o.s.s.) and closed side setting (c.s.s.). In addition to c.s.s., eccentricity is one of the major factors that determine the capacity of gyratory and cone crushers. The fragmentation of the material results from the continuous compression that takes place between the mantle and bowl liners. An additional crushing effect occurs between the compressed particles, resulting in less wear of the liners. This is also called interparticle crushing. The gyratory crushers are equipped with a hydraulic setting adjustment system, which adjusts c.s.s. and thus affects product size distribution. Depending on cone type, the c.s.s. setting can be adjusted in two ways. The first way is by rotating the bowl against the threads so that the vertical position of the outer wear part (concave) is changed. One advantage of this adjustment type is that the liners wear more evenly. Another principle of setting adjustment is by lifting/lowering the main shaft. An advantage of this is that adjustment can be done continuously under load. To optimize operating costs and improve the product shape, as a rule of thumb, it is recommended that cones always be choke-fed, meaning that the cavity should be as full of rock material as possible. This can be easily achieved by using a stockpile or a silo to regulate the inevitable fluctuation of feed material flow. Level monitoring devices that detect the maximum and minimum levels of the material are used to start and stop the feed of material to the crusher as needed.

Primary gyratory crushers are used in the primary crushing stage. Compared to the cone type crusher, a gyratory crusher has a crushing chamber designed to accept feed material of a relatively large size in relation to the mantle diameter. The primary gyratory crusher offers high capacity thanks to its generously dimensioned circular discharge opening (which provides a much larger area than that of the jaw crusher) and the continuous operation principle (while the reciprocating motion of the jaw crusher produces a batch crushing action). The gyratory crusher has capacities starting from 1200 to above 5000t/h. To have a feed opening corresponding to that of a jaw crusher, the primary gyratory crusher must be much taller and heavier. Therefore, primary gyratories require quite a massive foundation.

The cone crusher is a modified gyratory crusher. The essential difference is that the shorter spindle of the cone crusher is not suspended, as in the gyratory, but is supported in a curved, universal bearing below the gyratory head or cone (Figure 8.2). Power is transmitted from the source to the countershaft to a V-belt or direct drive. The countershaft has a bevel pinion pressed and keyed to it and drives the gear on the eccentric assembly. The eccentric assembly has a tapered, offset bore and provides the means whereby the head and main shaft follow an eccentric path during each cycle of rotation. Cone crushers are used for intermediate and fine crushing after primary crushing. The key factor for the performance of a cone type secondary crusher is the profile of the crushing chamber or cavity. Therefore, there is normally a range of standard cavities available for each crusher, to allow selection of the appropriate cavity for the feed material in question.

Depending on the size of the debris, it may either be ready to enter the recycling process or need to be broken down to obtain a product with workable particle sizes, in which case hydraulic breakers mounted on tracked or wheeled excavators are used. In either case, manual sorting of large pieces of steel, wood, plastics and paper may be required, to minimise the degree of contamination of the final product.

The three types of crushers most commonly used for crushing CDW materials are the jaw crusher, the impact crusher and the gyratory crusher (Figure 4.4). A jaw crusher consists of two plates, with one oscillating back and forth against the other at a fixed angle (Figure 4.4(a)) and it is the most widely used in primary crushing stages (Behera etal., 2014). The jaw crusher can withstand large and hard-to-break pieces of reinforced concrete, which would probably cause the other crushing machines to break down. Therefore, the material is initially reduced in jaw crushers before going through any other crushing operation. The particle size reduction depends on the maximum and minimum size of the gap at the plates (Hansen, 2004).

An impact crusher breaks the CDW materials by striking them with a high-speed rotating impact, which imparts a shearing force on the debris (Figure 4.4(b)). Upon reaching the rotor, the debris is caught by steel teeth or hard blades attached to the rotor. These hurl the materials against the breaker plate, smashing them into smaller particle sizes. Impact crushers provide better grain-size distribution of RA for road construction purposes, and they are less sensitive to material that cannot be crushed, such as steel reinforcement.

Generally, jaw and impact crushers exhibit a large reduction factor, defined as the ratio of the particle size of the input to that of the output material. A jaw crusher crushes only a small proportion of the original aggregate particles but an impact crusher crushes mortar and aggregate particles alike and thus generates a higher amount of fine material (OMahony, 1990).

Gyratory crushers work on the same principle as cone crushers (Figure 4.4(c)). These have a gyratory motion driven by an eccentric wheel. These machines will not accept materials with a large particle size and therefore only jaw or impact crushers should be considered as primary crushers. Gyratory and cone crushers are likely to become jammed by fragments that are too large or too heavy. It is recommended that wood and steel be removed as much as possible before dumping CDW into these crushers. Gyratory and cone crushers have advantages such as relatively low energy consumption, a reasonable amount of control over the particle size of the material and production of low amounts of fine particles (Hansen, 2004).

For better control of the aggregate particle size distribution, it is recommended that the CDW should be processed in at least two crushing stages. First, the demolition methodologies used on-site should be able to reduce individual pieces of debris to a size that the primary crusher in the recycling plant can take. This size depends on the opening feed of the primary crusher, which is normally bigger for large stationary plants than for mobile plants. Therefore, the recycling of CDW materials requires careful planning and communication between all parties involved.

A large proportion of the product from the primary crusher can result in small granules with a particle size distribution that may not satisfy the requirements laid down by the customer after having gone through the other crushing stages. Therefore, it should be possible to adjust the opening feed size of the primary crusher, implying that the secondary crusher should have a relatively large capacity. This will allow maximisation of coarse RA production (e.g., the feed size of the primary crusher should be set to reduce material to the largest size that will fit the secondary crusher).

The choice of using multiple crushing stages mainly depends on the desired quality of the final product and the ratio of the amounts of coarse and fine fractions (Yanagi etal., 1998; Nagataki and Iida, 2001; Nagataki etal., 2004; Dosho etal., 1998; Gokce etal., 2011). When recycling concrete, a greater number of crushing processes produces a more spherical material with lower adhered mortar content (Pedro etal., 2015), thus providing a superior quality of material to work with (Lotfi etal., 2017). However, the use of several crushing stages has some negative consequences as well; in addition to costing more, the final product may contain a greater proportion of finer fractions, which may not always be a suitable material.

The first step of physical beneficiation is crushing and grinding the iron ore to its liberation size, the maximum size where individual particles of gangue are separated from the iron minerals. A flow sheet of a typical iron ore crushing and grinding circuit is shown in Figure 1.2.2 (based on Ref. [4]). This type of flow sheet is usually followed when the crude ore contains below 30% iron. The number of steps involved in crushing and grinding depends on various factors such as the hardness of the ore and the level of impurities present [5].

Jaw and gyratory crushers are used for initial size reduction to convert big rocks into small stones. This is generally followed by a cone crusher. A combination of rod mill and ball mills are then used if the ore must be ground below 325 mesh (45m). Instead of grinding the ore dry, slurry is used as feed for rod or ball mills, to avoid dusting. Oversize and undersize materials are separated using a screen; oversize material goes back for further grinding.

Typically, silica is the main gangue mineral that needs to be separated. Iron ore with high-silica content (more than about 2%) is not considered an acceptable feed for most DR processes. This is due to limitations not in the DR process itself, but the usual customer, an EAF steelmaking shop. EAFs are not designed to handle the large amounts of slag that result from using low-grade iron ores, which makes the BF a better choice in this situation. Besides silica, phosphorus, sulfur, and manganese are other impurities that are not desirable in the product and are removed from the crude ore, if economically and technically feasible.

Beneficiation of copper ores is done almost exclusively by selective froth flotation. Flotation entails first attaching fine copper mineral particles to bubbles rising through an orewater pulp and, second, collecting the copper minerals at the top of the pulp as a briefly stable mineralwaterair froth. Noncopper minerals do not attach to the rising bubbles; they are discarded as tailings. The selectivity of the process is controlled by chemical reagents added to the pulp. The process is continuous and it is done on a large scale103 to 105 tonnes of ore feed per day.

Beneficiation is begun with crushing and wet-grinding the ore to typically 10100m. This ensures that the copper mineral grains are for the most part liberated from the worthless minerals. This comminution is carried out with gyratory crushers and rotary grinding mills. The grinding is usually done with hard ore pieces or hard steel balls, sometimes both. The product of crushing and grinding is a waterparticle pulp, comprising 35% solids.

Flotation is done immediately after grindingin fact, some flotation reagents are added to the grinding mills to ensure good mixing and a lengthy conditioning period. The flotation is done in large (10100m3) cells whose principal functions are to provide: clouds of air bubbles to which the copper minerals of the pulp attach; a means of overflowing the resulting bubblecopper mineral froth; and a means of underflowing the unfloated material into the next cell or to the waste tailings area.

Selective attachment of the copper minerals to the rising air bubbles is obtained by coating the particles with a monolayer of collector molecules. These molecules usually have a sulfur atom at one end and a hydrophobic hydrocarbon tail at the other (e.g., potassium amyl xanthate). Other important reagents are: (i) frothers (usually long-chain alcohols) which give a strong but temporary froth; and (ii) depressants (e.g., CaO, NaCN), which prevent noncopper minerals from floating.

crusher | definition | crusher selection and types of crusher | engineering intro

crusher | definition | crusher selection and types of crusher | engineering intro

The crusher is a machine that is designed such that to reduce the size of large rocks into smaller rocks like gravels. It is not only for that, but it is also used for recycling of the waste materials. Crusher is a multi-dimensional machine. Crusher has the ability of changing the form of material. In rock ores, crusher is used for the reduction in size or for making pieces of a solid mix i.e., composed of different raw materials and these pieces are used for the composition study of different raw materials.

Selection of crusher is quite a complicated process because of the availability of many kinds of crusher in the market. So, during selection keep following points in mind and find whether the crusher is able to do these specific functions or not.

If someone selects a crusher that has more capacity than his requirements, then it will be uneconomical. This is so because as crusher size increases, its fuel burning rate and maintenance cost will be more.

Primary crusher has the ability to receive the crushing material (a material that has to be crushed) directly from the source i.e., quarry thats why these types of crusher are fixed from where the material is taken. Primary crusher is only for the breaking of large stones into pieces (this mean primary crusher is not for the aggregate size material.). Examples of primary crushers are jaw crusher; hammer mill crusher and gyratory crusher. After receiving primary crusher crush the material and produce a new fresh reduce size of the source material. Primary crusher has only functioned up to that point.

Now a secondary crusher comes into action and further reduces the size. In secondary crusher some sizes of stones may pass directly from sieve number 4. Examples of secondary crushers are cone crusher, roll crusher and hammer mill crusher.

At the end tertiary crusher reduces the size of crushed pieces very much to the required size and it also brings the fineness to the crushed material. Tertiary crushers are at the job site andthese are small in size. The material is first transported from source with the help of a dump truck. Some tertiary crushers are roll crusher, rod mill crusher and ball mill crusher.

secondary gyratory crushers

secondary gyratory crushers

The use of large primary crushers made secondary crushing necessary, but this department was taken care of nicely by the existing lines of standard gyratory machines. In commercial crushed stone plants, there was gradual increase in the number of products, but generally a sufficient demand existed for the coarser grades for ballast and macadam roads to absorb the output. So for a time everything went along quite comfortably in this respect, and the operator concerned himself with the problem of getting out increased tonnage, selling his product as it was made, or stocking it during off-seasons for any particular grades.

Then came reinforced concrete, and with it a rapidly increasing demand for small sizes of crushed stone and gravel. It is hard to say when this demand began to assume sizeable proportions, but sooncommercial plants began to feel the effects of it, and to look for a remedy. For some time, as was quite logical, the remedy consisted of installing more small secondary crushers, generally small gyratories. This procedure assumed rather startling proportions in some large plants. For example, the array of crushers in the plant comprised one 48 primary, four No. 7.5 secondaries and a battery of finishing crushers that included four No. 6 and twelve No. 4. All were gyratories, although later, two sets of crushing rolls were added to augment the production of small stone.

Probably the earliest attempt to adapt the standard gyratory for reduction crushing service was the short-head arrangement, which consisted simply of an abbreviated crushing head, installed in the standard machine, with concaves to match. This device did not prove to be very successful; crushing stresses were concentrated at a point where the top shell was ill fitted to withstand them, and the throw at the point of discharge was too small to take fulladvantage of the increased diameter of discharge opening. Chronologically, this adoption is a rather venerable one; it antedates by a number of years the moreserious efforts to develop special fine-reduction crushers, a development which did not gather headway until1915 or so.

It would be a difficult matter to as certain just where this development had its inception; probably a great deal of parallel work was being done at the time by the various crusher builders. One of our own early experiments along these lines was the installation of special concaves in several of the No. 4 crushers in the plant to reduce the crushing angle. The results were encouraging enough to start a more thorough investigation into the design of crushing chambers.

The disc crusher was one of the first special machines brought out for fine crushing, and for several years this new type enjoyed a wide popularity. The single toggle jaw crusher was developed in larger sizes, and because it could be operated at closer settings than similar sizes of the Blake type, found quite a field of service in small plants as a reduction crusher.

The first important development in the move to adapt the gyratory crusher to fine crushing was the debut of the Superior McCully fine-reduction crusher, which was brought out a few years before Allis-Chalmers took over these crushers. This machine was designed along lines identical to those of the standard Superior McCully crusher with one important exception: instead of the orthodox tapered top shell of the standard machine, the new crusher was fitted with a cylindrically bored shell, the concaves being vertical and reversible. The crushing head was flared correspondingly, this additional flare resulting, for a given size of receiving opening, in a head of much larger diameter. For example, whereas the standard crusher with 10 receiving opening has a head diameter of about 27 at the bottom, the corresponding dimension for the 10 reduction crusher is about 40 Eccentric speeds were increased, and throws were adjusted for operation at close settings. Originally these machines were fitted with straight-face concaves; later the concaves were tapered at both ends to distribute the wear better; eventually non-choking concaves became standard equipment. It would be difficult for us, and tedious for the reader, were we to attempt to chronicle all of the development work, some of it successful and some not, which went on in the decade following the end of the first World War. One importantcontribution to the art was the high-speed, direct-connected Newhouse crusher, which introduced a new principle of crushing for cleanness and uniformity of product. Some 20 years ago the principle of the widely flared crushing head was combined with some other new and radical departures from current practice, and the cone crusher entered the reduction crushing field. Two interesting innovations incorporated in this machine were an unusually large throw and a spring loaded and adjustable crushing bowl.

Special Gyratory Concaves:About the same time that the cone crusher appeared, at least three different builders applied the principle of curved-profile crushing chambers, certainly the most important and far reaching improvement in crusher design that had been made for many years and possibly the greatest since the inception of the gyratory type. In our own case this development took the form of non-choking concaves, which could be installed in any of the existing models of gyratory crusher without any change in the shape of the crushing head. The type quickly became standard equipment in our reduction crushers, the Newhouse and Superior McCully fine reduction machines. But of equal importance was the fact that the efficiency of many hundreds of existing standard machines, of all ages and styles, was markedly improved at a very nominal cost by substituting these new curved concaves for the old straight-face liners. All crushers developed up to this time, except the very large machines of the gyratory type, were provided with some means of adjustment to compensate for wear or to adjust for variations in product size. The range of adjustment in most machines was small; adjustments in most cases required shutting down the machine. In the gyratory types, after a certain amount of adjustment was made, it was necessary to reset the concaves. This did not constitute any serious drawback in primary and secondary crushing service, because wear was slow generally and theexact setting of discharge opening was not a critical matter. With the increase in demand for fine crushing the situation altered; it was necessary to set crushers closer and to maintain the setting within closer limits. It was immediately apparent that a crusher with a large range of adjustment, withoutthe necessity of resetting the wearing parts, would be very desirable; as a matter of fact, the first cone crushers brought out incorporated such a feature, which proved to be very popular.

Crushingengineers have studied this problem along the lines of combining wide range with speed of adjustment. The result of this study was the introduction of the idea of supporting the main-shaft on an oil-operated hydraulic jack. This idea was first incorporated in a special model of the Newhouse crusher, designated as the Oil-Adjusted crusher, A few of these machines were built and tested under severe operating conditions, and the line would undoubtedly have been developed extensively had not the quiet period through the early 1930s effectively checked the demand for new crushers. We had not lost sight of the possibilities of this method of adjustment, however, and whenConditions showed signs of improvement we were ready to incorporate the oil adjustment feature into an entirely new machine, a machine which was to be designed in all its proportions specifically for reduction crushing, with a scientifically proportioned crushing chamber, quick-set adjustment, safety release for tramp-iron protection, and high speed operation for maximum capacity at close settings. This machine, the Type R, was brought out early in 1938.

Big and giant primary gyratoriescome with memories of the first World War. As a matter of fact, there is not a great deal more to tell so far as these machines are concerned, except for one more big jump in top size. This machine, which had reached a 48 receiving opening by 1910 and 54 shortly thereafter, was developed a few years later into the 60 size. The first 60 machines was built in 1926-27, and these crushers two of which were installed in a South American copper mine, set a world record in weight and proportions which still stands. These giant machines, weighing about 500 tons each, and rearing their steel frames to the height of a two-story building, are indeed a long step forward from the first tiny No. 2 Gates crusher that came out of the little shop in Chicago some 60 years ago.

perfecting the performance of secondary crushers | e & mj

perfecting the performance of secondary crushers | e & mj

The role of the secondary crushing circuit, like every other stage in mineral processing flowsheets, is to prepare the feed material for the next stage of the process. The equipment selected depends on the characteristics of the ore and the desired end-product. However, in most mineral processing applications, the ore is relatively abrasive, and this lends itself to breakage via compression.

Cone crushing often provides the lowest operating cost and the most reliable method of production, although some operations with softer or less abrasive ores can use secondary sizers, horizontal shaft impactors, hammer mills, or other machines, each of which have varying benefits and drawbacks.

Cone crushers are fed with pre-screened material from the primary crusher (usually a jaw crusher or primary gyratory), and the secondary crusher should always, if possible, have a scalped feed. Ideally, the deck on the scalping screen should have a cut point equal to the closed side setting (CSS) of the crusher.

The feed size to a secondary crusher is typically in the range of 50 mm to 250 mm (up to 300 mm). If the capacity is higher, the acceptable feed size gets larger. After crushing, the product is in the range of 0-60 mm (75 mm) diameter.

For mineral processing, secondary crushing can be used to prepare feed for downstream processes or to go directly to leaching. Downstream processes typically include tertiary crushing or primary grinding, with the tertiary crushers often being cone crushers or high-pressure grinding rolls (HPGRs), and the primary grinding mills being autogenous (AG) semiautogenous (SAG), or even rod or ball mills.

In most applications, the secondary crusher has a primary target of maximizing the reduction ratio and reducing the top size and F80 for the downstream equipment. However, in some applications, the target can be also to avoid over-crushing in heap leaching applications, for example.

In primary-secondary HPGR circuits, the secondary circuit can be closed with a screen to provide a consistent top size and gradation for optimizing HPGR performance. Closed circuited secondary crushing can also bring benefits if cones are used in tertiary crushing, too. However, the cost of the additional equipment is not always welcome.

Frank Drescher, head of the crushing technologies product line at thyssenkrupp Mining Technologies, explained: A typical aim [for secondary crushing] in mining applications is to reach a grain size distribution with 100% of the material smaller than a defined maximum size. In some applications an additional requirement is to produce a minimum number of fines. A crusher is not able to directly produce a specific grain size, so the discharge always contains a wide range from fines up to a maximum size, plus oversize. The solution is a crushing circuit with an arrangement of a crusher, a subsequent screen and a conveyor to return the oversize to the crusher.

For example: If the following process requires 100% less than 80 mm without a high quantity of fines, the crusher can produce 90% less than 80 mm. After screening out the 0-80 mm fraction, the oversize that is more than 80 mm material is rejected to the crusher and crushed again. To crush the feed directly to 100% less than 80 mm would require a bigger machine, more energy and the amount of fines would significantly increase.

Tero Onnela, director for engineering and RTD in the Crusher Wears business line for Metso Outotecs Consumables business area, explained: Its common that these conditions are not realized at the start of plant operation, if ever. Since the feed and ore properties will naturally fluctuate over time, its best to analyze and optimize the crushing chamber designs, operating setpoints, and equipment configuration regularly as the feed properties change over time.

Jeremy Polcyn, product sales support manager, in Metso Outotecs Services business area, added: Careful attention should be paid to the required product size, most commonly the P80, and the incoming feed size. The online grading analysis technology available today, for example, Metso Outotecs VisioRock can monitor these conditions and make changes to crusher parameters with the assistance of artificial intelligence.

When it comes to throughput, crushing circuits should always be assessed holistically, as changes to the operating parameters and throughput in one area will naturally affect the next. Trying to operate in a consistent manner can help to pinpoint where tweaks can be made most effectively and can indicate where higher profile liner upgrades may be utilized.

Drescher said: On the one hand, you have to consider which machine represents a bottleneck and thus limits the flow of the production line. But it also makes sense to look at a line as a whole. If the entire crushing process is distributed over several machines arranged in sequence, then its possible to change the influence of individual crushers on the entire process by altering their settings. This then has an influence on the wear of the individual crushers and the particle size distribution in the final product.

For example, in a simple arrangement, if the primary crusher produces a high quantity of fines, then more material is screened out and less material is fed to the secondary crusher, thus reducing wear. Various factors can influence the process, for example, the feed material might change due to natural fluctuations in crushability, hardness or moisture content. The product of individual crushing stages can also change due to wear of the crushing tools. In order to react to this, its important to regularly check the wear level of individual crushing stages as well as throughout the entire process.

Ekkhart Matthies, global applications director at Weir Minerals, said: The most important thing to remember when assessing a crusher is think about the bigger picture. No crusher works in a vacuum. Changes to one crusher often impact the equipment working alongside it and the stages that follow it.

While its important to routinely check on and evaluate critical pieces of machinery, refinements should be made with an application-wide view of the process or in partnership with application specialists.

Due to the arrival of Industrial Internet of Things (IIOT) and remote monitoring, it has never been easier to regularly check a crushers performance, Matthies added. Today, operators can monitor and analyze multiple pieces of equipment in real-time from the comfort of their desk. This may tempt users to become focused on machine-by-machine improvements. However, emphasis should always be placed upon holistic, site-wide optimization. Our Synertrex IIOT platform offers users the ability to monitor the performance and health of Weir process equipment across their flowsheet providing valuable insight to inform their wider optimization initiatives.

Bill Malone, global product director for crushers at FLSmidth, agreed: Its very important to monitor the settings and output from each crusher. And with modern control systems, this is possible. This ensures that a constant, or at least more normal product, is presented to the screens, which ensures stability in the system and therefore more consistent process results.

Normally, the frequency of monitoring will depend on the wear characteristics of the material and how often corrections have to be made to compensate for this. So, for a high-wear material, possibly once or twice per shift and, for a low-wear material, perhaps once or twice per week. If you have modern control systems installed, they will take care of this function automatically.

When a complete circuit is running in a consistent manner, varying output results are the most obvious indicator for when change is necessary. Secondary applications are dependent on the primary crusher to provide a targeted feed size, so fluctuations in the run-of-mine (ROM) ore can contribute considerably.

Changes in gradation (i.e., feed getting coarser or finer), hardness, moisture or, if the work index increases or decreases, can trigger adjustments in screen panels as well as potentially crusher mantles, bowls and concaves to compensate.

Mine planning and preparation can be a good indicator to prepare for change, explained Lucas Steiner, vice president for Metso Outotecs Mining Crusher Products business line. If its known that ore hardness or abrasiveness is going to change, preparations can be made and watched for in an effort to combat and maintain circuit performance.

There are also key indicators that change may be necessary in both the secondary crusher and in downstream tertiary crushers. These include symptoms such as sporadic or continuous force or power overloads, poor efficiency or utilization of available crushing work, short crushing chamber life, or performance inconsistency during the life of the crushing chamber.

Changes to major operational figures such as tonnage, power usage and the life of wear parts are indications that there may have been a change to the crushers operating conditions, Matthies said. Monitoring a crushers tonnages is the quickest and most noticeable sign your crusher is not performing optimally. Is your crusher discharge in line with your expectations?

By power usage we refer to how much electrical energy is being drawn from the motor, which is a subtler indication than tonnages. The motors amp reading can indicate if your crusher is suffering from lack of power, or if other factors are forcing your crusher to work harder to achieve its expected results.

Wear parts can also reveal a lot about a crushers condition. If wear patterns appear to have worn unusually or the life of the part has shortened, these suggest there are opportunities to alter the crushers settings and further improve its performance.

To optimize the performance of individual machines, the best course of action is to maintain operation of the crusher within three critical controlled variables: volumetric capacity, power draw and crushing force.

One of the best places to start on the optimization of individual machines is with manipulated variables like the CSS or speed. Sometimes controlled variables such as power draw can be used to manipulate crusher CSS and, lately online product gradation analyzers have been used to control crushers, aiming to stabilize their performance. There are also additional disturbance variables like crushing chamber wear and feed size.

To a certain extent, these disturbances can be compensated by manipulated variables when a sophisticated feedback control system is used, Onnela said. It can find the best operating parameters for the crusher and crushing chamber. Further step changes can be achieved by designing an application-specific crushing chamber with the aim of giving the best performance throughout its life within the limits the crusher sets.

A basic prerequisite for an analysis is to know the particle size distribution and the mass flow rates of the crusher feed and discharge. By monitoring these parameters, the crushing process can be influenced by adjusting crushing gaps, speed, etc.

Timely replacement of crushing tools is also an important point to ensure the efficiency of the crushing process as it reduces downtime and assembly costs, Richter said. The shape of the crushing tools has an influence on the product, crushing forces, energy consumption and wear, as well as utilization rate and service life. They can therefore contribute significantly to the optimization of the crushing process.

Wear parts and crusher upgrades play a highly critical role in crusher optimization, and the materials used have the potential to increase the service life and thus the time during which a machine operates optimally.

Steiner explained: Optimization of both crushing chamber profiles and wear-part materials can have a tremendous impact on machine performance, including the throughput capacity, reduction ratio, performance consistency and availability by improving the liner life. Also, crusher energy efficiency can be maximized by designing an application-specific crushing chamber. In some cases, reducing energy requirements by tens of percent.

Matthies agreed: Wear parts are, in my opinion, one of the most important factors when optimizing a crusher. Using the correct liner configuration, operators can increase the tonnage and quality of end-product delivered by their equipment. Every feed curve has an optimum liner configuration. The design of a crushers wear liners hugely impacts the performance of the crusher and its uptime.

Operators should also regularly check the crushers feed curve and the correlation between the motor power, chamber pressure and the tonnage. If the tonnage, motor power or crushing pressure is not what you would expect, there is room to optimize your crusher performance and the lifetime of its wear parts.

Manganese has been used in crushers for decades because of its work-hardening properties. As rocks meet the outer layer of the manganese particles, their exterior layer toughens. This results in a material that is harder to wear down during operation and can handle higher impact blows compared to other alloys.

Its a common misconception that more manganese increases the robustness of the wear part, Matthies explained. A manganese alloy will typically contain carbon, chrome and manganese elements. An increase in any of these ingredients will require adjustments to the wider recipe. Without considering the application and the wider formula, increases in manganese can result in weaker or less reliable parts.

Matthies said his team worked with an iron-ore mine in Russia supplying custom-engineered ESCO crusher liners, manufactured using premium alloys and an improved wear profile designed for that specific application. After the first set of ESCO liners were installed in the Trio TP600 crusher, the customer benefitted from four more days of wear life, a 16% increase in the bowl liner and a 20% increase in mantle utilization.

Sven Hoerschkes, head of GPLM, construction and feeders at FLSmidth, reported similar with his own customers: In some cases, weve delivered 10% extra capacity and 30%-40% longer liner lifetimes by optimizing their profiles and the material composition, he said. Its important to also check the screen performance too as this will affect the crusher significantly.

Steiner explained: There are numerous cases across different crusher models where we have optimized equipment and/or provided upgrades to get the most out of the machine and in cases secondary crushers. From MP1000 to MP1250 upgrades that have seen a 25% increase in throughput, to upgrades of Symons crushers that can decrease downtime and increase availability by as much as 25%.

In 2020, Weir Minerals replaced a competitor cone crusher within an iron-ore mine in China with a Trio TP900. The incumbent cone crusher was suffering from lack of availability and excessive downtime.

Circuit optimization should start with identifying the deficiencies and knowing the goals surrounding throughput/tonnage, material reduction, resource consumption (energy, water, etc.), machine reliability, machine availability and total cost of ownership. Identifying this gives information about where adjustments need to be made and, on what scale, from minor setting tweaks to larger scale upgrades.

Drescher explained: Its necessary to know and understand all the parameters (feed material, feed granulation, product granulation, mass flows), and the crushers must be adjusted so that circuit loads help improve the product and overall performance, not reduce the output.

For example, the primary crusher product size needs to be adjusted to the secondary crusher feed size or the AG/SAG feed size, and also the secondary unit product size needs to be adjusted to the mill or HPGR feed size, which needs to be adjusted according to concentrator specifications. The same logic needs to be applied for throughput and feed rates. Inaccurate adjustments usually lead to overall reduced plant technoeconomic efficiency, especially if its an integrated plant.

This task should be performed at the early stages of a project because, once the steel or civil works are finished and equipment is installed, the available space sets up clear limitations for new or additional equipment installations. Arrangement changes can also carry extraordinary costs.

Circuit performance should be monitored throughout the life of the plant, and mines should conduct a full range of lab tests and run a complete plant simulation when looking to make significant changes. Every person interviewed for this article recommended engaging an expert at this stage.

I understand that some operations may have their own process engineers. However, I would always recommend that original equipment suppliers and associated process specialists are consulted when approaching any optimization project, Matthies said.

ROM characteristics provide operators with information on the product hardness, feed curve, abrasiveness essentially predicting the flow sheet, equipment selection and possible equipment changes over time.

Because of this, circuit optimization requires a macro viewpoint of all equipment and targets within a flowsheet, along with a micro-view of crushers and other equipment on an individual basis. This can be hard for a mining company to achieve alone, and the utilization of experts at this stage can provide objective analysis and recommendations.

When it comes to detailed specifics on the crushers themselves, the highest level of support comes from people who are knowledgeable in the design and operation of the equipment along with wider experiences, Onnela said. In our Chamber Optimization Program, Metso Outotec uses in-house developed simulation tools and laboratory equipment to study detailed parameters and understand the crushing circuit, and how changes also influence the other equipment.

Improvements require measurements, and the capability to detect improvement potential from the measured data. Applying the latest digital technologies is adding an exciting new dimension to bettering the performance and lifetime of critical equipment such as crushers, and the ability to process big data is enabling valuable new performance and health-related services.

Onnela explained: Measuring inherent variable crushing conditions requires longer-term data to make high-quality conclusions and profitable decisions. In this work, digital technologies are a key enabler.

The ability to connect to crushers remotely allows access to huge amounts of accurate factual data. Supporting this, sensor development is also close to the level where we can talk about creating online digital twins of crushers, allowing scenario simulations and clear value-added action proposals based on data collected.

Sensor technology also diminishes the need for sampling data manually in conditions where people can face health and safety risks. Online sensing also gives a better overall view of the crusher performance condition compared to a sporadic sampling campaign.

The team at Weir recently supplies custom-engineered ESCO crusher liners to an iron-ore mine in Russia. The customer gains four more days of wear life with a 16% increase in the bowl liner life and a 20% increase in mantle utilization. (Photo: Weir Minerals)

Digital technologies are essentially bridging the data gap between end-users and experts, allowing issues to be identified before they arise and preventative measures to be taken where necessary. With the rapid expansion of data collection and storage, many OEMs are now being asked to upgrade existing equipment so that performance data can be collected, quickly analyzed and reviewed regularly, leading to better performance and reliability.

Having full equipment data insights is particularly important for the mining and aggregates industries given that equipment is typically dispersed over large areas. Being digitally connected enables operators and maintenance staff to monitor the performance and health of their equipment quickly from the safety of their office.

With the array of sensors and optical devices now available, real-time monitoring and, more importantly, instantaneous reaction to the results obtained, allows us to operate the crusher under its most efficient conditions, Malone concluded. We also now have a better understanding of the predictability of component life, which allows us to proactively plan maintenance and changeout schedules and prevent major time loss due to failure. This all leads to a quicker and safer way to work with a lot less downtime.

Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.

secondary impact crushers - meka crushing & screening plants

secondary impact crushers - meka crushing & screening plants

MSI and MSIH Series crushers are very versatile for the production of fine materials with a precise cubical shape. The robust design boosts productivity and ensures that our customers can successfully carry out difficult tasks. A high reduction ratio provides less recirculation in the crushing plant, thus decreasing the workload of the vibrating screens, conveyors and other crushers. As a result, overall maintenance and spare parts requirements for MEKAs crushing and screening plants are minimal compared to competitors plants.

MEKAs series of crushers have been designed to gain the trust and confidence of our customers. Our precisely machined welded construction rotors have proven construction, ensuring long-term use. In addition, all components are of premium quality in order to give our customers a trouble-free operation experience.

Our MSIH Series grinding impact crushers have a very competitive design for the asphalt recycling process. Our experienced engineering team has optimised the structure of the distributor plates to be less sensitive to sticky materials, separating these materials better, which is particularly important in the asphalt recycling processes. The MSIH Series design, with two independent breaker plates, is also optimized to provide better performance in concrete recycling processes.

MEKA secondary impact crushers are manufactured using two different designs in order to respond to our customers different needs. One of these designs is the MSI series secondary impact Crusher with two independent breaking plates, which may be adjusted by hydraulic setting rods. Their large feed opening is a key advantage for most applications requiring the feeding of materials up to 350 mm.

Alternatively, the grinding type of MSIH series secondary impact crusher provides a very high reduction ratio for crushing medium abrasive materials such as river gravel and basalt. Grinding types of crushers have distributor plates that are useful for separating sticky materials. Under the distributor plate, there are grinding plates that contribute to the production of fine cubical materials.

Get in Touch with Mechanic
Related Products
Recent Posts
  1. tractor power stone crusher video

  2. mining equipment utilization

  3. stationary crushers

  4. the best crypto mining equipment

  5. granite edge polishing machine

  6. lime stone crusher plant di usa com

  7. second hand zenith crushers

  8. how to use marble edging machine

  9. high quality stone stone crusher in jakarta

  10. different crushing value

  11. chinese jaw crusher design

  12. ball milling pdf

  13. khd cement mill

  14. best jaw crusher in brazil comparison

  15. clay rotary drum dryer manufacturer

  16. saudi arabia high end portable copper mine high efficiency concentrator sell

  17. internal structure of crusher

  18. vertically integrated textile mill definition

  19. rock crusher in homossassa

  20. petcock grinding in ball mill process