tl-1 | toolroom lathes | 8

tl-1 | toolroom lathes | 8" chuck | 10" chuck | lathes haas cnc machines

This price includes shipping cost, export and import duties, insurance, and any other expenses incurred during shipping to a location in France agreed with you as a buyer. No other mandatory costs can be added to the delivery of a Haas CNC Product.

* Not all options are compatible with each other. Some options may require the purchase of additional options, or may include additional options at no charge. Please use our Build-&-Price tool to determine option compatibility, and configure your machine.

The TL Series Toolroom Lathes are affordable, easy to use, and offer the precision control and flexibility of the Haas CNC system. The TL-1 is very easy to learn and operate even without knowing G-code. It is the perfect machine for start-up shops, or as a first step into CNC machining.

The Haas TL Series Toolroom Lathes are affordable, easy to use, and offer the precision control and flexibility of the Haas CNC system. Because they are very easy to learn and operate even without knowing G-code they are perfect for start-up shops, or as a first step into CNC machining.

Spend your time making chips, not cleaning them out of your machine. Our belt-type chip conveyor automatically removes chips from your machine, and discharges them at the height of a standard industrial barrel, with minimal coolant carryout. The belt-type chip conveyor can be turned on easily through your program, or straight from the control panel.

*Haas machines are designed to operate on 220 VAC power. An optional internal high-voltage transformer (380 - 480 VAC) is available for all models, except the Desktop Mill, CL-1, and CM-1. Note: This optional high-voltage internal transformer is not field installable; it must be ordered with the machine.

All prices and specifications subject to change without notice. Freight, rigging, state & local taxes, vendor installation charges, and dealer installed accessories are not included. Not responsible for misprints or typographical errors. Machines shown with optional equipment. Actual product appearance may differ.

This price includes shipping cost, export and import duties, insurance, and any other expenses incurred during shipping to a location in France agreed with you as a buyer. No other mandatory costs can be added to the delivery of a Haas CNC Product.

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vf-4ss | 40-taper mill | super speed | vertical mills haas cnc machines

vf-4ss | 40-taper mill | super speed | vertical mills haas cnc machines

This price includes shipping cost, export and import duties, insurance, and any other expenses incurred during shipping to a location in France agreed with you as a buyer. No other mandatory costs can be added to the delivery of a Haas CNC Product.

* Not all options are compatible with each other. Some options may require the purchase of additional options, or may include additional options at no charge. Please use our Build-&-Price tool to determine option compatibility, and configure your machine.

The Haas high-performance Super-Speed vertical machining centers provide the high spindle speeds, fast rapids, and quick tool changes necessary for high-volume production and reduced cycle times. Each SS machine features a 12,000-rpm, inline direct-drive spindle, an ultra-fast side-mount tool changer, and high-speed rapids on all axes.

*Haas machines are designed to operate on 220 VAC power. An optional internal high-voltage transformer (380 - 480 VAC) is available for all models, except the Desktop Mill, CL-1, and CM-1. Note: This optional high-voltage internal transformer is not field installable; it must be ordered with the machine.

All prices and specifications subject to change without notice. Freight, rigging, state & local taxes, vendor installation charges, and dealer installed accessories are not included. Not responsible for misprints or typographical errors. Machines shown with optional equipment. Actual product appearance may differ.

This price includes shipping cost, export and import duties, insurance, and any other expenses incurred during shipping to a location in France agreed with you as a buyer. No other mandatory costs can be added to the delivery of a Haas CNC Product.

We use cookies to improve your user experience. Our Cookie Notice describes which cookies we use, why we use them, and how you can find more information about them. Please confirm you consent to us using analytics cookies. If you do not consent, you may still use our website with a reduced user experience.

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ball mill - an overview | sciencedirect topics

ball mill - an overview | sciencedirect topics

The ball mill accepts the SAG or AG mill product. Ball mills give a controlled final grind and produce flotation feed of a uniform size. Ball mills tumble iron or steel balls with the ore. The balls are initially 510 cm diameter but gradually wear away as grinding of the ore proceeds. The feed to ball mills (dry basis) is typically 75 vol.-% ore and 25% steel.

The ball mill is operated in closed circuit with a particle-size measurement device and size-control cyclones. The cyclones send correct-size material on to flotation and direct oversize material back to the ball mill for further grinding.

Grinding elements in ball mills travel at different velocities. Therefore, collision force, direction and kinetic energy between two or more elements vary greatly within the ball charge. Frictional wear or rubbing forces act on the particles, as well as collision energy. These forces are derived from the rotational motion of the balls and movement of particles within the mill and contact zones of colliding balls.

By rotation of the mill body, due to friction between mill wall and balls, the latter rise in the direction of rotation till a helix angle does not exceed the angle of repose, whereupon, the balls roll down. Increasing of rotation rate leads to growth of the centrifugal force and the helix angle increases, correspondingly, till the component of weight strength of balls become larger than the centrifugal force. From this moment the balls are beginning to fall down, describing during falling certain parabolic curves (Figure 2.7). With the further increase of rotation rate, the centrifugal force may become so large that balls will turn together with the mill body without falling down. The critical speed n (rpm) when the balls are attached to the wall due to centrifugation:

where Dm is the mill diameter in meters. The optimum rotational speed is usually set at 6580% of the critical speed. These data are approximate and may not be valid for metal particles that tend to agglomerate by welding.

The degree of filling the mill with balls also influences productivity of the mill and milling efficiency. With excessive filling, the rising balls collide with falling ones. Generally, filling the mill by balls must not exceed 3035% of its volume.

The mill productivity also depends on many other factors: physical-chemical properties of feed material, filling of the mill by balls and their sizes, armor surface shape, speed of rotation, milling fineness and timely moving off of ground product.

where b.ap is the apparent density of the balls; l is the degree of filling of the mill by balls; n is revolutions per minute; 1, and 2 are coefficients of efficiency of electric engine and drive, respectively.

A feature of ball mills is their high specific energy consumption; a mill filled with balls, working idle, consumes approximately as much energy as at full-scale capacity, i.e. during grinding of material. Therefore, it is most disadvantageous to use a ball mill at less than full capacity.

The ball mill is a tumbling mill that uses steel balls as the grinding media. The length of the cylindrical shell is usually 11.5 times the shell diameter (Figure 8.11). The feed can be dry, with less than 3% moisture to minimize ball coating, or slurry containing 2040% water by weight. Ball mills are employed in either primary or secondary grinding applications. In primary applications, they receive their feed from crushers, and in secondary applications, they receive their feed from rod mills, AG mills, or SAG mills.

Ball mills are filled up to 40% with steel balls (with 3080mm diameter), which effectively grind the ore. The material that is to be ground fills the voids between the balls. The tumbling balls capture the particles in ball/ball or ball/liner events and load them to the point of fracture.

When hard pebbles rather than steel balls are used for the grinding media, the mills are known as pebble mills. As mentioned earlier, pebble mills are widely used in the North American taconite iron ore operations. Since the weight of pebbles per unit volume is 3555% of that of steel balls, and as the power input is directly proportional to the volume weight of the grinding medium, the power input and capacity of pebble mills are correspondingly lower. Thus, in a given grinding circuit, for a certain feed rate, a pebble mill would be much larger than a ball mill, with correspondingly a higher capital cost. However, the increase in capital cost is justified economically by a reduction in operating cost attributed to the elimination of steel grinding media.

In general, ball mills can be operated either wet or dry and are capable of producing products in the order of 100m. This represents reduction ratios of as great as 100. Very large tonnages can be ground with these ball mills because they are very effective material handling devices. Ball mills are rated by power rather than capacity. Today, the largest ball mill in operation is 8.53m diameter and 13.41m long with a corresponding motor power of 22MW (Toromocho, private communications).

Planetary ball mills. A planetary ball mill consists of at least one grinding jar, which is arranged eccentrically on a so-called sun wheel. The direction of movement of the sun wheel is opposite to that of the grinding jars according to a fixed ratio. The grinding balls in the grinding jars are subjected to superimposed rotational movements. The jars are moved around their own axis and, in the opposite direction, around the axis of the sun wheel at uniform speed and uniform rotation ratios. The result is that the superimposition of the centrifugal forces changes constantly (Coriolis motion). The grinding balls describe a semicircular movement, separate from the inside wall, and collide with the opposite surface at high impact energy. The difference in speeds produces an interaction between frictional and impact forces, which releases high dynamic energies. The interplay between these forces produces the high and very effective degree of size reduction of the planetary ball mill. Planetary ball mills are smaller than common ball mills, and are mainly used in laboratories for grinding sample material down to very small sizes.

Vibration mill. Twin- and three-tube vibrating mills are driven by an unbalanced drive. The entire filling of the grinding cylinders, which comprises the grinding media and the feed material, constantly receives impulses from the circular vibrations in the body of the mill. The grinding action itself is produced by the rotation of the grinding media in the opposite direction to the driving rotation and by continuous head-on collisions of the grinding media. The residence time of the material contained in the grinding cylinders is determined by the quantity of the flowing material. The residence time can also be influenced by using damming devices. The sample passes through the grinding cylinders in a helical curve and slides down from the inflow to the outflow. The high degree of fineness achieved is the result of this long grinding procedure. Continuous feeding is carried out by vibrating feeders, rotary valves, or conveyor screws. The product is subsequently conveyed either pneumatically or mechanically. They are basically used to homogenize food and feed.

CryoGrinder. As small samples (100 mg or <20 ml) are difficult to recover from a standard mortar and pestle, the CryoGrinder serves as an alternative. The CryoGrinder is a miniature mortar shaped as a small well and a tightly fitting pestle. The CryoGrinder is prechilled, then samples are added to the well and ground by a handheld cordless screwdriver. The homogenization and collection of the sample is highly efficient. In environmental analysis, this system is used when very small samples are available, such as small organisms or organs (brains, hepatopancreas, etc.).

The vibratory ball mill is another kind of high-energy ball mill that is used mainly for preparing amorphous alloys. The vials capacities in the vibratory mills are smaller (about 10 ml in volume) compared to the previous types of mills. In this mill, the charge of the powder and milling tools are agitated in three perpendicular directions (Fig. 1.6) at very high speed, as high as 1200 rpm.

Another type of the vibratory ball mill, which is used at the van der Waals-Zeeman Laboratory, consists of a stainless steel vial with a hardened steel bottom, and a single hardened steel ball of 6 cm in diameter (Fig. 1.7).

The mill is evacuated during milling to a pressure of 106 Torr, in order to avoid reactions with a gas atmosphere.[44] Subsequently, this mill is suitable for mechanical alloying of some special systems that are highly reactive with the surrounding atmosphere, such as rare earth elements.

A ball mill is a relatively simple apparatus in which the motion of the reactor, or of a part of it, induces a series of collisions of balls with each other and with the reactor walls (Suryanarayana, 2001). At each collision, a fraction of the powder inside the reactor is trapped between the colliding surfaces of the milling tools and submitted to a mechanical load at relatively high strain rates (Suryanarayana, 2001). This load generates a local nonhydrostatic mechanical stress at every point of contact between any pair of powder particles. The specific features of the deformation processes induced by these stresses depend on the intensity of the mechanical stresses themselves, on the details of the powder particle arrangement, that is on the topology of the contact network, and on the physical and chemical properties of powders (Martin et al., 2003; Delogu, 2008a). At the end of any given collision event, the powder that has been trapped is remixed with the powder that has not undergone this process. Correspondingly, at any instant in the mechanical processing, the whole powder charge includes fractions of powder that have undergone a different number of collisions.

The individual reactive processes at the perturbed interface between metallic elements are expected to occur on timescales that are, at most, comparable with the collision duration (Hammerberg et al., 1998; Urakaev and Boldyrev, 2000; Lund and Schuh, 2003; Delogu and Cocco, 2005a,b). Therefore, unless the ball mill is characterized by unusually high rates of powder mixing and frequency of collisions, reactive events initiated by local deformation processes at a given collision are not affected by a successive collision. Indeed, the time interval between successive collisions is significantly longer than the time period required by local structural perturbations for full relaxation (Hammerberg et al., 1998; Urakaev and Boldyrev, 2000; Lund and Schuh, 2003; Delogu and Cocco, 2005a,b).

These few considerations suffice to point out the two fundamental features of powder processing by ball milling, which in turn govern the MA processes in ball mills. First, mechanical processing by ball milling is a discrete processing method. Second, it has statistical character. All of this has important consequences for the study of the kinetics of MA processes. The fact that local deformation events are connected to individual collisions suggests that absolute time is not an appropriate reference quantity to describe mechanically induced phase transformations. Such a description should rather be made as a function of the number of collisions (Delogu et al., 2004). A satisfactory description of the MA kinetics must also account for the intrinsic statistical character of powder processing by ball milling. The amount of powder trapped in any given collision, at the end of collision is indeed substantially remixed with the other powder in the reactor. It follows that the same amount, or a fraction of it, could at least in principle be trapped again in the successive collision.

This is undoubtedly a difficult aspect to take into account in a mathematical description of MA kinetics. There are at least two extreme cases to consider. On the one hand, it could be assumed that the powder trapped in a given collision cannot be trapped in the successive one. On the other, it could be assumed that powder mixing is ideal and that the amount of powder trapped at a given collision has the same probability of being processed in the successive collision. Both these cases allow the development of a mathematical model able to describe the relationship between apparent kinetics and individual collision events. However, the latter assumption seems to be more reliable than the former one, at least for commercial mills characterized by relatively complex displacement in the reactor (Manai et al., 2001, 2004).

A further obvious condition for the successful development of a mathematical description of MA processes is the one related to the uniformity of collision regimes. More specifically, it is highly desirable that the powders trapped at impact always experience the same conditions. This requires the control of the ball dynamics inside the reactor, which can be approximately obtained by using a single milling ball and an amount of powder large enough to assure inelastic impact conditions (Manai et al., 2001, 2004; Delogu et al., 2004). In fact, the use of a single milling ball avoids impacts between balls, which have a remarkable disordering effect on the ball dynamics, whereas inelastic impact conditions permit the establishment of regular and periodic ball dynamics (Manai et al., 2001, 2004; Delogu et al., 2004).

All of the above assumptions and observations represent the basis and guidelines for the development of the mathematical model briefly outlined in the following. It has been successfully applied to the case of a Spex Mixer/ Mill mod. 8000, but the same approach can, in principle, be used for other ball mills.

The Planetary ball mills are the most popular mills used in MM, MA, and MD scientific researches for synthesizing almost all of the materials presented in Figure 1.1. In this type of mill, the milling media have considerably high energy, because milling stock and balls come off the inner wall of the vial (milling bowl or vial) and the effective centrifugal force reaches up to 20 times gravitational acceleration.

The centrifugal forces caused by the rotation of the supporting disc and autonomous turning of the vial act on the milling charge (balls and powders). Since the turning directions of the supporting disc and the vial are opposite, the centrifugal forces alternately are synchronized and opposite. Therefore, the milling media and the charged powders alternatively roll on the inner wall of the vial, and are lifted and thrown off across the bowl at high speed, as schematically presented in Figure 2.17.

However, there are some companies in the world who manufacture and sell number of planetary-type ball mills; Fritsch GmbH (www.fritsch-milling.com) and Retsch (http://www.retsch.com) are considered to be the oldest and principal companies in this area.

Fritsch produces different types of planetary ball mills with different capacities and rotation speeds. Perhaps, Fritsch Pulverisette P5 (Figure 2.18(a)) and Fritsch Pulverisette P6 (Figure 2.18(b)) are the most popular models of Fritsch planetary ball mills. A variety of vials and balls made of different materials with different capacities, starting from 80ml up to 500ml, are available for the Fritsch Pulverisette planetary ball mills; these include tempered steel, stainless steel, tungsten carbide, agate, sintered corundum, silicon nitride, and zirconium oxide. Figure 2.19 presents 80ml-tempered steel vial (a) and 500ml-agate vials (b) together with their milling media that are made of the same materials.

Figure 2.18. Photographs of Fritsch planetary-type high-energy ball mill of (a) Pulverisette P5 and (b) Pulverisette P6. The equipment is housed in the Nanotechnology Laboratory, Energy and Building Research Center (EBRC), Kuwait Institute for Scientific Research (KISR).

Figure 2.19. Photographs of the vials used for Fritsch planetary ball mills with capacity of (a) 80ml and (b) 500ml. The vials and the balls shown in (a) and (b) are made of tempered steel agate materials, respectively (Nanotechnology Laboratory, Energy and Building Research Center (EBRC), Kuwait Institute for Scientific Research (KISR)).

More recently and in year 2011, Fritsch GmbH (http://www.fritsch-milling.com) introduced a new high-speed and versatile planetary ball mill called Planetary Micro Mill PULVERISETTE 7 (Figure 2.20). The company claims this new ball mill will be helpful to enable extreme high-energy ball milling at rotational speed reaching to 1,100rpm. This allows the new mill to achieve sensational centrifugal accelerations up to 95 times Earth gravity. They also mentioned that the energy application resulted from this new machine is about 150% greater than the classic planetary mills. Accordingly, it is expected that this new milling machine will enable the researchers to get their milled powders in short ball-milling time with fine powder particle sizes that can reach to be less than 1m in diameter. The vials available for this new type of mill have sizes of 20, 45, and 80ml. Both the vials and balls can be made of the same materials, which are used in the manufacture of large vials used for the classic Fritsch planetary ball mills, as shown in the previous text.

Retsch has also produced a number of capable high-energy planetary ball mills with different capacities (http://www.retsch.com/products/milling/planetary-ball-mills/); namely Planetary Ball Mill PM 100 (Figure 2.21(a)), Planetary Ball Mill PM 100 CM, Planetary Ball Mill PM 200, and Planetary Ball Mill PM 400 (Figure 2.21(b)). Like Fritsch, Retsch offers high-quality ball-milling vials with different capacities (12, 25, 50, 50, 125, 250, and 500ml) and balls of different diameters (540mm), as exemplified in Figure 2.22. These milling tools can be made of hardened steel as well as other different materials such as carbides, nitrides, and oxides.

Figure 2.21. Photographs of Retsch planetary-type high-energy ball mill of (a) PM 100 and (b) PM 400. The equipment is housed in the Nanotechnology Laboratory, Energy and Building Research Center (EBRC), Kuwait Institute for Scientific Research (KISR).

Figure 2.22. Photographs of the vials used for Retsch planetary ball mills with capacity of (a) 80ml, (b) 250ml, and (c) 500ml. The vials and the balls shown are made of tempered steel (Nanotechnology Laboratory, Energy and Building Research Center (EBRC), Kuwait Institute for Scientific Research (KISR)).

Both Fritsch and Retsch companies have offered special types of vials that allow monitoring and measure the gas pressure and temperature inside the vial during the high-energy planetary ball-milling process. Moreover, these vials allow milling the powders under inert (e.g., argon or helium) or reactive gas (e.g., hydrogen or nitrogen) with a maximum gas pressure of 500kPa (5bar). It is worth mentioning here that such a development made on the vials design allows the users and researchers to monitor the progress tackled during the MA and MD processes by following up the phase transformations and heat realizing upon RBM, where the interaction of the gas used with the freshly created surfaces of the powders during milling (adsorption, absorption, desorption, and decomposition) can be monitored. Furthermore, the data of the temperature and pressure driven upon using this system is very helpful when the ball mills are used for the formation of stable (e.g., intermetallic compounds) and metastable (e.g., amorphous and nanocrystalline materials) phases. In addition, measuring the vial temperature during blank (without samples) high-energy ball mill can be used as an indication to realize the effects of friction, impact, and conversion processes.

More recently, Evico-magnetics (www.evico-magnetics.de) has manufactured an extraordinary high-pressure milling vial with gas-temperature-monitoring (GTM) system. Likewise both system produced by Fritsch and Retsch, the developed system produced by Evico-magnetics, allowing RBM but at very high gas pressure that can reach to 15,000kPa (150bar). In addition, it allows in situ monitoring of temperature and of pressure by incorporating GTM. The vials, which can be used with any planetary mills, are made of hardened steel with capacity up to 220ml. The manufacturer offers also two-channel system for simultaneous use of two milling vials.

Using different ball mills as examples, it has been shown that, on the basis of the theory of glancing collision of rigid bodies, the theoretical calculation of tPT conditions and the kinetics of mechanochemical processes are possible for the reactors that are intended to perform different physicochemical processes during mechanical treatment of solids. According to the calculations, the physicochemical effect of mechanochemical reactors is due to short-time impulses of pressure (P = ~ 10101011 dyn cm2) with shift, and temperature T(x, t). The highest temperature impulse T ~ 103 K are caused by the dry friction phenomenon.

Typical spatial and time parameters of the impactfriction interaction of the particles with a size R ~ 104 cm are as follows: localization region, x ~ 106 cm; time, t ~ 108 s. On the basis of the obtained theoretical results, the effect of short-time contact fusion of particles treated in various comminuting devices can play a key role in the mechanism of activation and chemical reactions for wide range of mechanochemical processes. This role involves several aspects, that is, the very fact of contact fusion transforms the solid phase process onto another qualitative level, judging from the mass transfer coefficients. The spatial and time characteristics of the fused zone are such that quenching of non-equilibrium defects and intermediate products of chemical reactions occurs; solidification of the fused zone near the contact point results in the formation of a nanocrystal or nanoamor- phous state. The calculation models considered above and the kinetic equations obtained using them allow quantitative ab initio estimates of rate constants to be performed for any specific processes of mechanical activation and chemical transformation of the substances in ball mills.

There are two classes of ball mills: planetary and mixer (also called swing) mill. The terms high-speed vibration milling (HSVM), high-speed ball milling (HSBM), and planetary ball mill (PBM) are often used. The commercial apparatus are PBMs Fritsch P-5 and Fritsch Pulverisettes 6 and 7 classic line, the Retsch shaker (or mixer) mills ZM1, MM200, MM400, AS200, the Spex 8000, 6750 freezer/mill SPEX CertiPrep, and the SWH-0.4 vibrational ball mill. In some instances temperature controlled apparatus were used (58MI1); freezer/mills were used in some rare cases (13MOP1824).

The balls are made of stainless steel, agate (SiO2), zirconium oxide (ZrO2), or silicon nitride (Si3N). The use of stainless steel will contaminate the samples with steel particles and this is a problem both for solid-state NMR and for drug purity.

However, there are many types of ball mills (see Chapter 2 for more details), such as drum ball mills, jet ball mills, bead-mills, roller ball mills, vibration ball mills, and planetary ball mills, they can be grouped or classified into two types according to their rotation speed, as follows: (i) high-energy ball mills and (ii) low-energy ball mills. Table 3.1 presents characteristics and comparison between three types of ball mills (attritors, vibratory mills, planetary ball mills and roller mills) that are intensively used on MA, MD, and MM techniques.

In fact, choosing the right ball mill depends on the objectives of the process and the sort of materials (hard, brittle, ductile, etc.) that will be subjecting to the ball-milling process. For example, the characteristics and properties of those ball mills used for reduction in the particle size of the starting materials via top-down approach, or so-called mechanical milling (MM process), or for mechanically induced solid-state mixing for fabrications of composite and nanocomposite powders may differ widely from those mills used for achieving mechanically induced solid-state reaction (MISSR) between the starting reactant materials of elemental powders (MA process), or for tackling dramatic phase transformation changes on the structure of the starting materials (MD). Most of the ball mills in the market can be employed for different purposes and for preparing of wide range of new materials.

Martinez-Sanchez et al. [4] have pointed out that employing of high-energy ball mills not only contaminates the milled amorphous powders with significant volume fractions of impurities that come from milling media that move at high velocity, but it also affects the stability and crystallization properties of the formed amorphous phase. They have proved that the properties of the formed amorphous phase (Mo53Ni47) powder depends on the type of the ball-mill equipment (SPEX 8000D Mixer/Mill and Zoz Simoloter mill) used in their important investigations. This was indicated by the high contamination content of oxygen on the amorphous powders prepared by SPEX 8000D Mixer/Mill, when compared with the corresponding amorphous powders prepared by Zoz Simoloter mill. Accordingly, they have attributed the poor stabilities, indexed by the crystallization temperature of the amorphous phase formed by SPEX 8000D Mixer/Mill to the presence of foreign matter (impurities).

what's the difference between sag mill and ball mill - jxsc machine

what's the difference between sag mill and ball mill - jxsc machine

A mill is a grinder used to grind and blend solid or hard materials into smaller pieces by means of shear, impact and compression methods. Grinding mill machine is an essential part of many industrial processes, there are mainly five types of mills to cover more than 90% materials size-reduction applications.

Do you the difference between the ball mill, rod mills, SAG mill, tube mill, pebble mill? In the previous article, I made a comparison of ball mill and rod mill. Today, we will learn about the difference between SAG mill vs ball mill.

AG/SAG is short for autogenous mill and semi-autogenous mill, it combines with two functions of crushing and grinding, uses the ground material itself as the grinding media, through the mutual impact and grinding action to gradually reduce the material size. SAG mill is usually used to grind large pieces into small pieces, especially for the pre-processing of grinding circuits, thus also known as primary stage grinding machine. Based on the high throughput and coarse grind, AG mills produce coarse grinds often classify mill discharge with screens and trommel. SAG mills grinding media includes some large and hard rocks, filled rate of 9% 20%. SAG mill grind ores through impact, attrition, abrasion forces. In practice, for a given ore and equal processing conditions, the AG milling has a finer grind than SAG mills.

The working principle of the self-grinding machine is basically the same as the ball mill, the biggest difference is that the sag grinding machine uses the crushed material inside the cylinder as the grinding medium, the material constantly impacts and grinding to gradually pulverize. Sometimes, in order to improve the processing capacity of the mill, a small amount of steel balls be added appropriately, usually occupying 2-3% of the volume of the mill (that is semi-autogenous grinding).

High capacity Ability to grind multiple types of ore in various circuit configurations, reduces the complexity of maintenance and coordination. Compared with the traditional tumbling mill, the autogenous mill reduces the consumption of lining plates and grinding media, thus have a lower operation cost. The self-grinding machine can grind the material to 0.074mm in one time, and its content accounts for 20% ~ 50% of the total amount of the product. Grinding ratio can reach 4000 ~ 5000, more than ten times higher than ball, rod mill.

Ball mills are fine grinders, have horizontal ball mill and vertical ball mill, their cylinders are partially filled with steel balls, manganese balls, or ceramic balls. The material is ground to the required fineness by rotating the cylinder causing friction and impact. The internal machinery of the ball mill grinds the material into powder and continues to rotate if extremely high precision and precision is required.

The ball mill can be applied in the cement production plants, mineral processing plants and where the fine grinding of raw material is required. From the volume, the ball mill divide into industrial ball mill and laboratory use the small ball mill, sample grinding test. In addition, these mills also play an important role in cold welding, alloy production, and thermal power plant power production.

The biggest characteristic of the sag mill is that the crushing ratio is large. The particle size of the materials to be ground is 300 ~ 400mm, sometimes even larger, and the minimum particle size of the materials to be discharged can reach 0.1 mm. The calculation shows that the crushing ratio can reach 3000 ~ 4000, while the ball mills crushing ratio is smaller. The feed size is usually between 20-30mm and the product size is 0-3mm.

Both the autogenous grinding mill and the ball mill feed parts are welded with groove and embedded inner wear-resistant lining plate. As the sag mill does not contain grinding medium, the abrasion and impact on the equipment are relatively small.

The feed of the ball mill contains grinding balls. In order to effectively reduce the direct impact of materials on the ball mill feed bushing and improve the service life of the ball mill feed bushing, the feeding point of the groove in the feeding part of the ball mill must be as close to the side of the mill barrel as possible. And because the ball mill feed grain size is larger, ball mill feeding groove must have a larger slope and height, so that feed smooth.

Since the power of the autogenous tumbling mill is relatively small, it is appropriate to choose dynamic and static pressure bearing. The ball bearing liner is made of lead-based bearing alloy, and the back of the bearing is formed with a waist drum to form a contact centering structure, with the advantages of flexible movement. The bearing housing is lubricated by high pressure during start-up and stop-up, and the oil film is formed by static pressure. The journal is lifted up to prevent dry friction on the sliding surface, and the starting energy moment is reduced. The bearing lining is provided with a snake-shaped cooling water pipe, which can supply cooling water when necessary to reduce the temperature of the bearing bush. The cooling water pipe is made of red copper which has certain corrosion resistance.

Ball mill power is relatively large, the appropriate choice of hydrostatic sliding bearing. The main bearing bush is lined with babbitt alloy bush, each bush has two high-pressure oil chambers, high-pressure oil has been supplied to the oil chamber before and during the operation of the mill, the high-pressure oil enters the oil chamber through the shunting motor, and the static pressure oil film is compensated automatically to ensure the same oil film thickness To provide a continuous static pressure oil film for mill operation, to ensure that the journal and the bearing Bush are completely out of contact, thus greatly reducing the mill start-up load, and can reduce the impact on the mill transmission part, but also can avoid the abrasion of the bearing Bush, the service life of the bearing Bush is prolonged. The pressure indication of the high pressure oil circuit can be used to reflect the load of the mill indirectly. When the mill stops running, the high pressure oil will float the Journal, and the Journal will stop gradually in the bush, so that the Bush will not be abraded. Each main bearing is equipped with two temperature probe, dynamic monitoring of the bearing Bush temperature, when the temperature is greater than the specified temperature value, it can automatically alarm and stop grinding. In order to compensate for the change of the mill length due to temperature, there is a gap between the hollow journal at the feeding end and the bearing Bush width, which allows the journal to move axially on the bearing Bush. The two ends of the main bearing are sealed in an annular way and filled with grease through the lubricating oil pipe to prevent the leakage of the lubricating oil and the entry of dust.

The end cover of the autogenous mill is made of steel plate and welded into one body; the structure is simple, but the rigidity and strength are low; the liner of the autogenous mill is made of high manganese steel.

The end cover and the hollow shaft can be made into an integral or split type according to the actual situation of the project. No matter the integral or split type structure, the end cover and the hollow shaft are all made of Casting After rough machining, the key parts are detected by ultrasonic, and after finishing, the surface is detected by magnetic particle. The surface of the hollow shaft journal is Polished after machining. The end cover and the cylinder body are all connected by high-strength bolts. Strict process measures to control the machining accuracy of the joint surface stop, to ensure reliable connection and the concentricity of the two end journal after final assembly. According to the actual situation of the project, the cylinder can be made as a whole or divided, with a flanged connection and stop positioning. All welds are penetration welds, and all welds are inspected by ultrasonic nondestructive testing After welding, the whole Shell is returned to the furnace for tempering stress relief treatment, and after heat treatment, the shell surface is shot-peened. The lining plate of the ball mill is usually made of alloy material.

The transmission part comprises a gear and a gear, a gear housing, a gear housing and an accessory thereof. The big gear of the transmission part of the self-grinding machine fits on the hollow shaft of the discharge material, which is smaller in size, but the seal of the gear cover is not good, and the ore slurry easily enters the hollow shaft of the discharge material, causing the hollow shaft to wear.

The big gear of the ball mill fits on the mill shell, the size is bigger, the big gear is divided into half structure, the radial and axial run-out of the big gear are controlled within the national standard, the aging treatment is up to the standard, and the stress and deformation after processing are prevented. The big gear seal adopts the radial seal and the reinforced big gear shield. It is welded and manufactured in the workshop. The geometric size is controlled, the deformation is prevented and the sealing effect is ensured. The small gear transmission device adopts the cast iron base, the bearing base and the bearing cap are processed at the same time to reduce the vibration in operation. Large and small gear lubrication: The use of spray lubrication device timing quantitative forced spray lubrication, automatic control, no manual operation. The gear cover is welded by profile steel and high-quality steel plate. In order to enhance the stiffness of the gear cover, the finite element analysis is carried out, and the supporting structure is added in the weak part according to the analysis results.

The self-mill adopts the self-return device to realize the discharge of the mill. The self-returning device is located in the revolving part of the mill, and the material forms a self-circulation in the revolving part of the mill through the self-returning device, discharging the qualified material from the mill, leading the unqualified material back into the revolving part to participate in the grinding operation.

The ball mill adopts a discharge screen similar to the ball mill, and the function of blocking the internal medium of the overflow ball mill is accomplished inside the rotary part of the ball mill. The discharge screen is only responsible for forcing out a small amount of the medium that overflows into the discharge screen through the internal welding reverse spiral, to achieve forced discharge mill.

The slow drive consists of a brake motor, a coupling, a planetary reducer and a claw-type clutch. The device is connected to a pinion shaft and is used for mill maintenance and replacement of liners. In addition, after the mill is shut down for a long time, the slow-speed transmission device before starting the main motor can eliminate the eccentric load of the steel ball, loosen the consolidation of the steel ball and materials, ensure safe start, avoid overloading of the air clutch, and play a protective role. The slow-speed transmission device can realize the point-to-point reverse in the electronic control design. When connecting the main motor drive, the claw-type Clutch automatically disengages, the maintenance personnel should pay attention to the safety.

The slow drive device of the ball mill is provided with a rack and pinion structure, and the operating handle is moved to the side away from the cylinder body The utility model not only reduces the labor intensity but also ensures the safety of the operators.

the composition and function of the main structure system of ball mill - hxjq mining machine manufacturer

the composition and function of the main structure system of ball mill - hxjq mining machine manufacturer

The driving and execution system includes four-bar mechanism of belt and hinge and executive component like tray; power system mainly consists of motor. A deeper understanding of equipment system can help to smoothly realize the purpose of equipment reconstruction optimization. The following is a detailed introduction to ball mill system composition and function.

3. Power system: the motor belongs to YC series, namely single-phase capacitor start asynchronous motor. The motor features high starting torque and sound performance with the advantages of small volume, light weight and convenient maintenance. This series of asynchronous motor is designed at the national level abiding by the standard released by IEC (international electro-technical commission). The voltage of motor is 220 v, and the motor can operate with maximum capacity of 100 PF. It is widely used in small machinery, medical equipment, household appliances, etc.

modelling and control of ball mill grinding

modelling and control of ball mill grinding

Dynamic experiments were performed in a continuous open-circuit 4040 cm ball mill using a pseudo-random binary sequence of the feed rate and measuring the variations of the discharge particle-size distribution. The impulse response is calculated by a cross- correlation technique. Then a model involving a discrete transfer function and a time-series stochastic equation is calibrated using maximum likelihood methods.

A continuous grinding experiment is performed in a Denver 40 x 40 cm grate discharge ball mill. The mill feed (quartz in the range of600-1700 um) is delivered by a PI-controlled belt conveyor accurate to 1%. The water addition to the mill is automatically adjusted by a peristaltic pump to maintain a constant percentage of solids in the feed (65%). A PDP 11/23 mini-computer is used for remote set-points control.

Fiaure 2 gives the auto and crosscorrelation functions of the various measured variables of the grinding test. The autocorrelograms show that both ore feed and discharge rates are white. This was expected for the feed rate since a PRBS was used. The results for the mill discharge rate indicate that the dynamic behaviour of the mill load is faster than the sampling period, i.e. that the mill solids hold-up weight reaches an equilibrium within 45 seconds after a feed rate variation.

The studied model relates dynamically the mill discharge product size P to the mill feed rate F. Since the sampling interval is too large to characterize the dynamics of the mill discharge rate and percentage of solids, the models for these two variables are not considered here.

The residuals together with the observed and deterministic process outputs, are in this particular case mainly due to measurement (sampling and analysis) errors. However they have not a zero mean, since the model is unable to represent the unequal distribution at the experimental points around the mean value of P which is observed in the assymetrical shape of the P histogram.

A possible approach for limiting the variability of the manipulated variable is to estimate u(i) such that the weighted sum of the variances of u(i) and e(i) is minimum. This leads to the well-known Linear-Quadratic-Gaussian (LQG) control. Another approach, known as the one-step ahead MV controller yields a sub-optimal control law without the complicated mathematics of the LOG.

This study shows that it is possible with appropriate experiments to find a dynamic linear empirical model of a continuous grinding ball mill the advantage of empirical modelling compared to phenomenological modelling is its ability to represent the experimental facts as they are without forcing them to obey a preconceived model structure. The universal structure of the model is an other advantage which gives access to the standard mathematical tools for process identification and control.

Illustrations of this point are given by the application of the maximum likelihood method to the estimation of the mill model parameters and the application of the minimum variance control theory to the control of the product fineness by the ore feed rate. It is shown by simulation that, for different types or minimum variance controllers and different types of disturbances, the MV controller exhibits better performances than an optimally tuned PID controller. However it is very demanding for the actuators and can lead to irrealistic or unstable control laws. The one-step ahead MV controller exhibits a safer behaviour than the unconstrained MV controller since it allows a flexible limitation of the feed rate variations. When the product fineness disturbances are strongly non-stationary, it is shown that a constraint on the feed rate variation between successive values is very efficient to eliminate the controller offset and reduce the oscillation of the feed rate.

The empirical approach to grinding modelling and control presents also some implementation difficulties. First of all since the process model unavoidly changes with time, it must be estimated by adaptive methods such as it is in self-tuning controllers. Second the MV controller requires the knowledge of the

The disturbances model; which has to be identified by off-line or on-line estimation procedures. Furthermore, when the disturbances model structure changes the MV controller becomes less efficient than the PID controller. Again, adaptive procedures are required to track the noise model. Finally when the structure of the randomly occuring deterministic disturbances is different from the stochastic disturbances structure (related for instance to measurement inaccuracies), more elaborate control strategies based on state-space formulation have to be considered.

screening media | mineral screening multotec

screening media | mineral screening multotec

From wedge wire sieve bends and centrifuge baskets to completely optimised composite screen decks, Multotec is a leading screening media technology solutions provider for the global minerals processing industry.

We supply products covering the full range of screening applications, including sizing, dewatering, scalping and desliming. Refined over 45 years experience in mineral screening applications, Multotec manufactures one of the worlds largest ranges of rubber, polyurethane, wedge wire, steel and composite screening media.

Your local Multotec branch provides turnkey screening media solutions, with short lead times on screening media products, and engineering and field services to ensure your screening plant is optimised for your processing conditions, material and the output targets.

Multotec screening media has been developed in response to the worlds toughest mineral screening applications. We offer this global technology to the worlds mining and mineral processing houses through an established worldwide footprint that includes a complete network of branches and distributors in almost 100 countries on 6 continents.

Your local Multotec experts offer complete turnkey solutions for screening media installations, including design and engineering, installation and commissioning, and wear monitoring and field service support. Our teams will ensure the optimum screening media solution is supplied according to your specific plant and process parameters and requirements, such as feed tonnage required, the average particle size and the particle shape.

Multotec can design and build completely customised screening decks. Drawing on one of the worlds largest ranges of purpose-specific screen panels from materials including rubber, polyurethane, steel, woven-wire, ceramics, Hardox, fibreglass and combinations of these materials we can optimise each area of your screen deck to suit the conditions, your material and output targets.

A popular composite deck configuration is to place a set of panels with highly impact-resistant material at the feed end of the screen, where the impact of material from the feed box or chute is highest.

Weve supplied composite screen decks with over a dozen different types of panels, with each panel fulfilling a specific function. The apertures will be chosen according to the screens purpose and factors like the feed tonnage required, the average particle size and the particle shape. That way, we can ensure maximum mineral screening efficiency at the lowest overall cost.

Our monitoring software Hawkeye provides complete real time and historical intelligence of the condition of your screening media. Through accurately indicating screen media wear, Hawkeye helps optimise wear-related maintenance and reduces downtime, while ensuring your screening media reliably delivers the cut size your plant required.

By enabling plant operations and technical teams to systematically manage and analyse wear data from the screening deck, Hawkeye also provides a powerful planning system for on-going application improvement. By tracking the performance over time of the various panel types on each deck in operation, the screening requirements in each part of the deck can be constantly refined.

Multotec screen panels are manufactured standard with visual wear indicators. These wear indicators comprise four or five moulded cavities in the body of the panel, spaced at predetermined intervals below the upper wear surface. As the panel surface is worn away, so the individual cavities become visible, the final cavity of which indicates that a replacement must be conducted or planned shortly.

This simple but innovative system, patented by Multotec, not only indicates when replacement needs to take place, but can be used as a data source to measure the rate of wear so that a future replacement time can be predicted and planned.

Blinding occurs when dirt, minerals and other substances adhere and bridge across the apertures of your screening surface, creating a stubborn paste that blocks material from screening through. Pegging describes the presence of irregular material lodged in the screen apertures, and occurs when stones are about the same size as the holes.

Multotec, in partnership with universities across the globe, is constantly developing and testing new innovations and technologies to respond the challenges our customers face in processing minerals more efficiently, and at a lower cost. Our screening equipment of today reflects over 45 years of innovation and optimisation in the worlds largest mining and mineral processing operations.

Roy has been involved in mining and metallurgy since 1981, and has vast global experience in both the production and sales side of the industry, across Africa, Australia and South America. His commitment to product development, business development and customer satisfaction has made Roche one of the worlds leading experts in screening media solutions.

belt conveyor and belt conveyor parts

belt conveyor and belt conveyor parts

Belt conveyor, for now, has the largest apply range in transportation equipment for materials. Belt conveyor is very convenient equipment, especially in aclinic and inclined transportation. It is widely used in modern industries, like: underground mine roadway, mine ground transportation system, open-pit mine and concentrating plant. To satisfy different plants working line needs, our company can customize a belt conveyor with various conveying process requirements. We can do single delivery or multiple components or form a transportation system with other transportation equipment.

Belt conveyor is the most ideal -efficient and continuous transportation equipment for cement. Compared to other kinds of transportation equipment, it can conveyors longer distances, larger load and more successive transportation. It also has characters of automation, reliable running, and centralized control.

Belt conveyor applies widely, because of its advantages, in melting, mining, transportation, water and electricity, chemical engineering and so on. It also plays a big role in building materials, light industry, grains, ports, and shipping.

We normally will consider the different application scenarios, working environment, technological characters and materials and diversify belt conveyor into : large angle belt machine, deep groove belt machine and belt press machine, tubular belt type, air cushion belt type, flat turning belt type, line friction type, corrugated rib conveyor belt type transportation machinery, etc.

Classified by usage, there are general mobile type of belt conveyor, downhole selection, open-pit mine fixed type, special structure type, displaceable conveyor, loader special transfer function type, large inclined angle conveyor, etc., generally, short-distance conveyor in a factory can do aclinic or vertical transportation. The reversible pattern belt conveyor can be used for two-way conveying of materials. The cantilever machine is usually installed on the stacker and can be rotated to realize the function of dumping and supported by the gantry. The overhead machine is usually used in conjunction with other bulk material processing equipment, such as in hydropower construction, and can be configured with a standard intermediate frame that is placed on the sleeper for easy displacement; Classified according to the category of transport materials, used for general loose materials, belt conveyors for hard materials and single-piece materials, etc., classified according to the position of the rubber conveyor belt carrying section, including the belt carrying section above and carrying below and at the same time with the upper and lower sections. The two-way conveyor can transport the materials in the upper branch and the lower branch respectively, but in order to keep the material contact surface unchanged, the rubber belt needs to be periodically flipped.

what is an inching drive?

what is an inching drive?

When you hear the term inching drive, you might think of a small actuator, possibly driven by a piezo or voice coil, suitable for short, precise movements in applications such as optical inspection. (At least, thats what I envisioned when I first heard of an inching drive!) But inching drives are so named because of their ability to move very large, high-inertia loads at very slow speeds.

The two most commonly used terms are inching drive and auxiliary drive, but other terms for these low-power, high-torque drives include barring drive, creeping drive, jack drive, turning gear, and my favorite Sunday drive.

An inching drive is used as an auxiliary system to the main drive for a large machine such as a ball mill, industrial kiln, conveyor, or elevator. Its purpose is to turn the equipment at a speed slower than the normal operating speed typically 1 to 2 rpm, although fractional rpms are also common and to do so at high torque typically 120 percent of the normal drive torque.

Three main components make up the inching drive an electric motor or internal combustion engine, a gear reducer, and a connecting element to automatically or manually engage with the equipment being driven. The use of either an electric motor or an internal combustion engine depends both on the type of equipment being driven and the conditions under which the inching drive will be used. For example, a kiln needs to be rotated constantly. If the main power supply fails, an inching drive with an internal combustion engine can rotate the kiln in the absence of power. But for most other types of equipment,the inching drive is used primarily during maintenance and repair operations. In these cases, electric motors are the more common choice because they can provide positioning accuracy and good holding capabilities.

The mounting configuration of an inching drive can be parallel shaft, concentric shaft, or right angle. The mounting configuration is important for space considerations, but it also determines the type of gear reducer used in the inching drive. Parallel shaft configurations primarily use a helical gear or double-worm gear, although worm gears have low efficiency and are typically chosen only when self-locking is desirable. Concentric shaft designs also use helical gears, while right-angle designs most often use a combination of spiral bevel and helical gears.

In addition to the motor, gearbox, and coupling, most inching drive systems incorporate safety features, such as a brake or backstop, to prevent the drive from rotating when power is removed and to keep the equipment from rotating if its stopped in an unbalanced position.

A variable speed drive can generally provide inching or creeping capabilities which eliminates the need for a separate inching drive as long as the motor is capable of operating within the speed range required for inching.

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