wet ball mill/wet type ball mill/wet ball milling machine--zhengzhou bobang heavy industry machinery co.,ltd

wet ball mill/wet type ball mill/wet ball milling machine--zhengzhou bobang heavy industry machinery co.,ltd

Wet type ball mill are mostly used in the industry production. It is to increase the high grinding efficiency under the ball mill grinding and striking, from which the granularity is even and no flying dust with little noise, being the most universal powder machine in the benefication as powder grinding the ferrous metal like gold, silver, plumbum, zinc,copper,molybdenum,manganese,tungsten etc, as the nonmetal powder grinding like graphite,feldspar, potash feldspar, phosphorus ore, fluorite, clay, and swell soil etc. The wet type ball mill need to add the liquid into the grinding ball media auxiliary (water or ethanol). The material output gate is trumpet shape, with screw device inside, easy to discharging the material.

Copyright Zhengzhou Bobang Heavy Industry Machinery Co.,Ltd. E-mail : [email protected] Tel0086- 86656957 Address No.11 West Construction Road, Zhongyuan District,Zhengzhou City,Henan Province, China

wet grinding mill

wet grinding mill

Wet Grinding Mills is mainly used for separation of gold, silver, lead, zinc, molybdenum,iron, copper, antimony, tungsten, tin and other minerals selected. With less investment, fast results, small footprint saving power, sturdiness and durability, ease of maintenance and high return on investment. It is the preferred production for alternative ball mill, is ideal for smalland medium enterprises dressing.

1.Firstlythemotorwilltransmitthemotivepowertoreductiongears,underthedriveofreductiongearsthatpassingthroughlargeverticalspindle,thenthepowercabienttransferstoabovewhippletree.

3.Afteraddingintoore,thematerialsareundertheextrusionofgrindingrollerweighttorevolutingandrotatingwithrunnerwheels,whentwistingthatcomingintobeinghugefrictionforcewithgrindingbase,aftersufferingrepeatedextrusion,rub,grindingthatbecrushedthoroughly.

4.Undertheeffectionofgrindingrolleroperating,thecrushedmaterialsandthewater mixed intensively to float on it uniformly,then passing through the overflow discharge gate that setting up on the mill basin to discharge,after thatenter intonext operation procedure to process.

rabbit lake uranium mill complex, canada

rabbit lake uranium mill complex, canada

The approximate 400 kilometers of highway were only open for a few weeks in the winter when the lakes and boggy ground were frozen. The schedule for the project had to reflect this very serious constraint on availability of access for construction materials and equipment.

In 1968, an affiliate of Gulf Oil Corporation acquired the rights to explore for minerals on 3.5 million acres in the Wollaston Lake Ford Belt located in the province's northeastern border. Using sophisticated technology, Gulf confirmed the existence of uranium deposits averaging five pounds of uranium oxide per ton of ore.

Originally, the plant was equipped with a semi-autogenous mill rated for 1,650-tons-per-day capacity. Screening followed with the oversized rock going back to the mill, and select rock being pumped into the cyclone separators. Acid leaching with counter-current decantation was followed by solvent extraction. The uranium solution is then treated with ammonia, which gives ammonium diuranate precipitate. This is dried in a multi-hearth dryer to produce U3O8, which is finally packed into steel drums for transportation.

As the ore grade declined, it became necessary to treat 2,000 tons per day rather than the designed 1,500. To achieve this increased tonnage, Fluor subsequently installed a ball mill following the cascade mill. The ball mill operates in a closed circuit with the hydrocyclones.

The diesel generator plant consisted of three 2,500-kilowatt units. Waste heat from the plant was channeled to heat the offices and workshop areas for energy conservation. At such a remote location, it was advantageous to minimize the labor force, and a high degree of automation was installed in the plant.

Procurement, expediting, and logistics played a critical role in this restricted site location. The schedule for the project had to reflect this very serious constraint on availability of access for construction materials and equipment.

Mobilization started immediately after the November 1971 contract award to meet the first ice haul period. In the summer of 1972, all construction facilities had to be readied and foundation work was started on the main building. Engineering had to progress rapidly to meet construction and structural steel drawings so that building materials could be sent up during the next season's ice haul period. Advanced planning required that different materials were delivered during each ice haul.

Fuel was always the major priority. The project entailed 235 truckloads in the first ice haul, 477 truckloads in the second ice haul, then 374 truckloads over a Canadian Government installed semi-permanent road.

In addition to supply deliveries, some winter concrete work was required. The concrete set required special attention to be heated and the work area thermally maintained at 25 degrees centigrade for over a week.

Delivering significant cost savings to the Client, Fluor housed only three of the six counter-current decantation thickeners in the building. Heat balances revealed that it was adequate to house half the thickeners outside.

At full production in 1978, the Rabbit Lake mill produced over 4 million tons of uranium oxide. The uranium oxide, or yellow cake, would be processed for sale to nuclear power plants, primarily in Europe.

vertical roller mills: the new leader in grinding technology

vertical roller mills: the new leader in grinding technology

Historically the reefs were rich and large profits were made with ordinary recovery circuits but today mines are dealing with complicated ores that require fine grinding to allow a 92% 98% recovery rate just to stay in the game.

Being well established in the cement industry with a 55% market share worldwide, the company has taken the proven design concepts and adapted it to the ore industry, specifically gold, copper, phosphates and iron. To support the equipment, Loesche has a team of highly qualified staff dedicated to ensuring customer service and satisfaction is achieved.

The particle size is critical for a sufficient degree of mineral liberation to expose the mineral and the grindability of the ores fluctuate, hence the beneficiation process and especially the comminution process must be flexible.

Dry and wet grinding technologies were compared in terms of grinding performance and product quality. Through significant laboratory work done, improved flotation performances of dry ground products have led to the design of a completely new beneficiation process.

The Loesche VRM has adaptable grinding modules which are already proven to be the way forward in other mining industries, allowing for variant mineral ores to be milled efficiently to the required particle size.

The VRM, depending on the roller size, has a high reduction ratio; feed from 80 mm to 140 mm to a product of P80 at 75 m in one pass, the mill is a closed circuit on its own having the comminution and classification of product in a single machine.

Sulphide copper-gold ores are usually sorted by flotation. The standard comminution process to grind the ore to flotation fineness, mostly consists of coarse crushing followed by SAG milling or wet ball mill circuits, or alternatively multiple stage crushing followed by rod and ball milling.

The two most common compressive comminution technologies are the high pressure grinding roller (HPGR) and the vertical-roller-mill (VRM). For now, the HPGR has already presented in a noteworthy number of mining projects whereas VRM technology, a new entrant, is still not fully accepted.

This is considered a resistance to change considering that VRM technology has a clearly dominant position in classical dry, compressive comminution applications like grinding of cement or granulated blast-furnace slag.

The VRM produces a steeper particle size distribution, reducing wastage in the form of ultra-fines and oversize, by this the VRM allows for a good flotation size range having more particles exposed to the floatation process.

Loesche VRM comminution technology is a particle on particle in bed grinding principle, cracking the ore on the mineral lines to expose more minerals to the floatation process with very low specific wear on the liners to produce cleaner concentrates.

Dry product allows for a surge silo to operate between the comminution and recovery circuits which ensures accurate, constant feed. This consistent flow with cleaner concentrates reduces reagent consumption.

By this a smaller footprint can be envisaged, reducing water absorption and evaporation. Increased water reclamation and less pollutants will be experienced affecting the nett operating expenditure to process a ton of ore.

Challenges from the strict environmental regulations have allowed Loesche VRM technology to become the future in comminution, enabling mining houses to operate in previously difficult conditions not suited to wet processes.

The OGP is a modular containerised comminution circuit laboratory where a Loesche milling specialist will be on hand performing various grinding tests until the optimum solution is reached for downstream processes.

uranium solvent extraction process

uranium solvent extraction process

The ore occurs as uraninite adhering to the outside of sand grains in the Wind River formation which rest unconformably upon Cretaceous shales. The ores are relatively low in clay content and generally regarded as exceptionally clean ores from the standpoint of objectionable impurities. The arkosic sands in which the ore occurs are very porous and permeable, having been laid down in scoured channels in the bentonitic clays.

Although extensive ore reserves in the area will require underground mining methods, significant ore reserves were also found near the surface which can be mined by open pit methods. All ore presently being mined by Petrotomics Company is by open pit under contract to Plateau Construction Company of Rawlins, Wyoming. Initial stripping of 2.3 million yards of overburden started in July, 1959 using Euclid TS24 scrapers and Euclid tractors for pushers. The ore zone is mined using a 2-yard Bucyrus-Erie shovel and a Koeh-ring shovel equipped with a backhoe front and also a crane front for drop ball use. Euclid trucks of 14.7 yard capacity with heated boxes are used for haulage to the mill which is one-half mile away. Ore control is stressed and accurately followed.

Future mining will utilize backfilling of the mined out pits for holding stripping waste instead of dumps. Stripping is carried out with four scrapers on two shifts. Mining is performed on day shift only. Mercury vapor flood lights are placed at essential points where night stripping is taking place. The water encountered in mining has ranged between 200 and 350-GPM and is pumped from the low point in the pit, utilizing a 40 HP pump mounted on a floating platform.

The mine-run ore, after being scalped of minus 4-inch fines, is crushed in a 30 x 40 Jaw Crusher. Oversize crusher was selected to accommodate large size lumps and thus avoid secondary breaking in the pit.

With the exception of occasional lenses of hard limestone, no blasting is required. The mill feed consists entirely of the ore mined by Petrotomics. The feed assays 0.25 to 0.30 U3O8, and the overall recovery is in the mid-nineties.

The test work was performed in the metallurgical laboratories of Kerr McGee Oil Industries, Inc., near Golden, Colorado, by Mr. Emmerson Kemp, Metallurgist for Petrotomics Company and the Kerr-MeGee research staff, in cooperation with A. H. Ross and Associates, of Toronto, Metallurgical Consultants to Petrotomics. The latter are also metallurgical consultants for the operation.

As soon as the flowsheet was finalized in June, 1961, Stearns Roger Manufacturing Company was engaged for the mill design and construction. Mill design and construction started immediately. Despite the severe winter, which had temperatures of 30 below zero and colder, construction was completed on schedule and milling commenced on April 5, 1962. Mr. Harry J. McMichael and Mr. Bruce H Irwin were project manager and project engineer, respectively for Stearns-Roger, and worked in close cooperation with Mr. Norman Grant and Mr. Emmerson Kemp of the Petrotomics Company and A. H. Ross and Associates during all phases of design and construction. This modern mill and flowsheet is a tribute to present day engineering practices. Simplicity was the keynote of the efficient Petrotomics Mill design.

All water used in milling originates from the open pit mine. The mine water is pumped to a 5,000,000 gallon holding pond and then to an elevated 200,000 gallon water tank. The top one-half of the tank capacity is available for milling purposes. If the water level should drop to this point, there is still water available for fire protection. The water pressure in the plant is 50-psi.

Power is supplied by the R.E.A. at 39,000-volts and reduced to 13,000-volts at the mill substation. All mill equipment operates at 440 and 110-volts. The mill has approximately 750 connected horsepower. A standby 250 KVA power unit is available in the mill to supply emergency power for the leach agitators, thickeners, tailing pumps, boilers, lighting, and other uses in the office, cafeteria, and sleeping quarters.

The milling process consists of crushing, grinding, acid leaching, countercurrent decantation, solvent extraction of the pregnant liquor, and precipitation as shown on the flowsheet. Additional details are given below.

The ore from the mine is dumped directly into the 40 ton coarse ore bin using 22 ton trucks or by means of a four yard front end loader from the ore stockpiles. The coarse ore bin, which is equipped with a 24 opening rail grizzly, is discharged by a 42 x 12 Apron Ore Feeder to a 42 x 5 vibrating grizzly with a 4 opening. The ore is very soft and sandy in nature so a large part of the feed is immediately removed as

Two 5 x 4 SRL-C Pumps (one standby) receive the ball mill discharge and feed a 14 Krebs Cyclone. The cyclone underflow returns to the ball mill. The cyclone overflow is minus 35-mesh and ready for acid leaching.

primary undersize by the vibrating grizzly. The oversize (plus 4-inch) from the grizzly passes to a 30 x 40 Jaw Crusher. This crusher is of much larger capacity than actually required but was selected to accommodate large size lumps and to avoid secondary breaking in the pit. A hopper with screw conveyor discharge is placed under the apron feeder to continually remove any leakage of fine sand and convey it to the primary belt conveyor.

A 24 belt conveyor with a suspended magnet over the head pulley delivers the grizzly undersize and jaw crusher product to a 5 x 12 vibrating screen equipped with a 5/8 x 5 slotted-type screen deck. The screen oversize passes to an impact crusher and is then returned to the primary conveyor by means of an 18 conveyor. This provides closed circuit secondary crushing operation. The vibrating screen undersize discharges to a 24 belt conveyor with a tripper to deliver the fine ore to one of two 700-ton fine ore bins. The design capacity of the crushing plant is 125 tons per hour. The fine ore bins are of conical-shape with large area bottom openings to facilitate discharging damp ore.

View of the leaching, precipitation, filtration, and repulping section from the mill superintendents office. Note one level construction with operating walkways above. Operators are shown in precipitation and filtration area. Yellow cake repulping agitator is shown directly beneath operators floor. The 14 x 14 Leach Agitators are in upper right corner. Precipitation agitators are shown in the background at the left.

The fine ore bins are discharged by two 60 x 30 variable speed belt ore feeders which deliver the plant feed to an 18 conveyor ahead of the ball mill. This belt is equipped with a conveyor scale. The 6 x 8 ball mill is provided with a drum feeder and discharges at 65-67 percent solids through a trommel screen attached to the mill and then to a 5 x 4 SRL-C Pump. An identical pump is available for standby service. The pump feeds a 14 Krebs Cyclone which operates in closed circuit with the ball mill. The cyclone overflow is sampled with a Automatic Sampler to provide the head sample for the plant feed. The ore is ground to 35-mesh. Cyclone operates at inlet pressure of 7 psi. Cyclone overflow, all minus 28-mesh, flows by gravity to raw leach section.

The ground ore at 52% solids enters five 14 x 14 Heavy Duty Turbine Agitators operating in series. The agitators provide approximately nine hours of retention time. Sulphuric acid and sodium chlorate are added to the first agitator at the rate of 60.0-pounds per ton and 2.00-pounds per ton, respectively. The resulting pH is 1.2 and EMF is 425. Provision is made so that sulphuric acid can be added to any or all agitators, but to date it has only been necessary to add the acid to the first agitator. The agitators are equipped with No. 10 Worm-Gear Reducer Drives and

Leaching of the ground ore with sulphuric acid and sodium chlorate is performed in five 14 x 14 Heavy Duty Turbine Agitators. The retention time is approximately nine hours. Leach tanks are of wood and are covered. Worm Gear Reducers are used to drive the leach agitators.

Close-up view of one leach agitator. Feed can be bypassed from any agitator without disturbing the circuit during inspection or maintenance periods. The agitators are equipped with rubber covered shafts attached to 54 diameter, 150% pitch, six bladed, rubber covered Turbine Propellers.

rubber covered shafts attached to 54 diameter, 150% pitch, six bladed, rubber covered Turbine Propellers. The propellers are attached to the shafts by means of an acme thread. Each agitator has a 20-HP motor. Wood tanks have 4 nominal staves and bottoms.

The agitators are arranged so that the feed can be bypassed from any unit without disturbing the circuit during inspection or maintenance periods. An automatic pH recorder and controller is provided for regulation of optimum dissolution conditions. In excess of 97.0% of the contained uranium is dissolved in the agitators.

The discharge from the leaching circuit is delivered to the countercurrent decantation washing system using a 3 x 3 SRL Pump. A second identical pump is installed for standby service. The washing system consists of six 55 diameter by 12 deep Heavy Duty Acid Proof Thickeners. The thickeners operate at approximately 19% solids at a pH of 1.5. Each thickener is equipped with two 4 duplex Adjustable Stroke Diaphragm Pumps (one for standby) for advancing the thickener underflows at approximately 55% solids. Approximately 100-GPM of fresh water and 100-GPM of raffinate solution from the solvent extraction system are added as wash solution to the last thickener and overflowed into 180-degree launders. The pregnant liquor overflowing No. 1 thickener contains approximately 1.5-grams U3O8 per liter.

The thickener tanks are constructed of 4 nominal thickness wood staves. The shafts, rake arms and tie rods are rubber covered and driven by a 60 enclosed running-in-oil Mechanism mounted on beam- type superstructures. Superstructures were fabricated and shipped in one piece to reduce installation costs. The rake blades and all wetted hardware are of 316 stainless steel. The Diaphragm Pumps have rubber lined bowls, rubber valve seats and lead impregnated ball valves. Experimental work is being conducted in the use of ceramic ball valves and results look favorable. Metal parts in contact with the acid pulp are of 316 stainless steel.

Separan NP-10 and glue are added to the thickeners as flocculants in quantities of 0.05 and 0.04 pounds per ton of solids, respectively. The Separan is prepared as a 0.25% solution. The glue is prepared as a 1.0% solution in a 3 x 3 agitator using a No. 6 Dry Reagent Feeder to slowly add the dry glue powder to the agitator. The only steam employed in the plant is used in preparing the glue solution.

The pregnant liquor from the No. 1 thickener is further clarified in a 22 diameter by 12 deep Acid Proof Clarifying Thickener. The shaft and rake assembly are rubber covered and tank is of 3 wood construction. The underflow is returned to the feed well of the No. 1 washing thickener. The overflow from the clarifying thickener is pumped to a 400-square-foot precoat filter for final clarification and stored in a 28 diameter by 20 deep tank preparatory to solvent extraction.

The washed underflow solids (tailings) from No. 6 thickener are sampled using a Automatic Sampler and then pumped through a 6 wood pipe to the tailing pond approximately 1600-feet away. Two 5 x 4 SRL-C Pumps (one standby) are used to pump the tailings. The portion of non-cycled raffinate and bleed from the filtration circuit are added to the tailing pump sump and discarded.

Six 55 diameter x 12 deep Heavy Duty Acid Proof Thickeners are used for countercurrent decantation washing of the leached solids. The shafts, rake arms, and tie rods are rubber covered to prevent corrosion from the acid pulp. The mechanisms are driven by a 60 gear reducer mounted on beam type superstructures.

The domestic uranium industry has lead the way in developing and establishing the undeniable proof that solvent extraction could be economically and technically applied to the treatment of ores and metallurgical products.

The pregnant leach solution is pumped through a flowmeter and then to the solvent extraction system. This consists of four extraction stages and four stripping stages which are all accomplished in a compartmented rectangular shaped tank measuring 28 wide by 82 long by 6 high. The tank is constructed of reinforced concrete lined with fiber glass for protection from the acidic solutions. Wood weirs and PVC piping were also provided between each mixer-settler compartment. The settling compartments in the stripping section are approximately one-half the area of the extraction compartments.

The countercurrent flow of aqueous and organic in the extraction cycles is accomplished using Solvent Extraction Pumping Turbines constructed of 316 stainless steel. No auxiliary pumps or airlifts are required for organic recycle within the extraction mixers or for the advance of the aqueous and organic solutions. The flow through the extraction cycles is approximately

Each washing thickener is equipped with two 4 duplex Adjustable Stroke Diaphragm Pumps. One pump is used for standby service. The pumps have rubber lined bowls, rubber valve seats, and lead impregnated ball valves. Ceramic ball valves are also being tested with favorable results.

The overflow from the No. 1 thickener (pregnant liquor) is clarified in the 22 diameter by 12 deep Acid Proof Clarifying Thickener. The underflow is returned to the feed well of the No. 1 washing thickener. Overflow is pumped to storage and then to solvent-extraction.

Close up view of the 28 wide by 82 long by 6 high compartmented solvent extraction and stripping unit. The Solvent-Extraction units incorporate a counter-current flow principle which is accomplished without the customary acid-proof piping and pumps.

Overall view of the solvent extraction and stripping unit. The pregnant leach liquor after passing through a precoat filter is treated by solvent extraction. The countercurrent flow of aqueous and organic is accomplished using Solvent Extraction Pumping Turbines. Recovery of uranium from the pregnant leach solution by solvent extraction is in excess of 99%.

Two of the three 10 x 12 Precipitation Agitators are shown here. Filling, precipitation, and discharging is alternately employed for each agitator. Magnesium oxide is used to precipitate the uranium. Two slowly revolving wood paddles attached to a wood shaft by means of 316 stainless steel fittings provide the gentle action required for ideal precipitation conditions.

200-GPM of pregnant leach liquor having a pH of 1.5 and containing approximately 1.5-grams of U3O8 per liter. The organic solution consists of a mixture of 2.5% Alamine 336, 2.0% Isodecanol and 95.5% kerosene.

The raffinate (spent leach solution) is sampled with a Automatic Sampler and after passing through an organic scavenging tank is split so that one-half is used for solution back wash in the countercurrent decantation circuit and the other one-half is discarded with the tailings.

The pregnant organic solution contains approximately 2.5-grams of U3O8 per liter and represents a flow of 160-GPM. This solution enters the stripping circuit and is contacted with 1.5N sodium chloride solution strip solution having a pH of 1.5 with sulphuric acid.

Recovery of contained uranium from the pregnant leach solution by solvent extraction is in excess of 99%. The mixer-settler units used in stripping are of the same design principle as the extraction units. The Mixing-Pumping Turbines and shafts, however, are constructed of mild steel covered with 1/8 paraline. The barren organic solution is returned to a 12 x 12 storage tank and reused in the extraction circuit.

Provision was made to regenerate the organic solution for removal of molybdenum but to date the content of molybdenum has been so low that regeneration has not been necessary. Nevertheless, this safeguard is available whenever required. Chemical consumptions are shown in Table II.

The pregnant strip solution containing 30-40 grams of U3O8 per liter and representing a flow of approximately 9.5-GPM is pumped to one of three 10 x 12 Precipitation Agitators. Magnesium oxide is added to a pH of 7.0 to precipitate the uranium. The precipitation agitators are equipped with two slowly revolving paddles. The shaft and paddles are of wood construction with 316 stainless steel fittings. The tanks are of wood and equipped with baffles. Filling, precipitation, and discharging is alternately employed for each agitator.

The precipitated slurry is pumped to a filter press where the yellow cake is filtered and water washed. The filtrate is refiltered in a second filter press to insure complete recovery of the solids. The final filtrate is split so that approximately 20% is bled to waste and 80% is returned to the strip solution make-up tanks.

The raffinate is sampled with a Automatic Sampler ahead of the organic scavenging tank. One half of the raffinate is discarded and the other one-half is used for solution back wash in the washing thickeners.

The filtered yellow cake is repulped with water in a 6 x 6 Vertical Turbine Agitator designed with an oversize turbine operated at slow speed to avoid breaking down the precipitate. It is pumped to a 6 diameter by 6 hearth dryer. Vangas is used for fuel. The dried yellow cake is discharged by gravity through a small hammermill to break-up any lumps and then to a screw conveyor. Three discharge spouts are provided in the screw conveyor to automatically fill a concentrate drum and signal when it has been filled.

The exhaust from the dryer passes through a dry cyclone which removes some yellow cake and discharges into the screw conveyor. The remaining dust is removed in a wet dust collector and the slurry is pumped to the clarified pregnant liquor storage tank where the yellow cake is immediately dissolved and reprocessed through the solvent extraction system.

Equipment Company wishes to thank Petrotomics Company for permission to describe their Shirley Basin Uranium Operation. Special thanks are extended to Mr. Norman A. Grant, Project Manager; Mr. G. K. Coates, Mill Superintendent; and Mr. Emmerson Kemp, Metallurgist and General Foreman, for their assistance in providing the information for this article. We also would like to thank Stearns-Roger Manufacturing Company for their cooperation in supplying the excellent photographs shown in this mill description.

Crushing crew consists of two men. Maintenance consists of two crews comprised of two mechanics and one helper overlapping to cover the week. All are on duty on Wednesday and consequently this is the major maintenance day.

Aerial view of the 500 ton per day Petrotomics Uranium Mill with office, cafeteria, and sleeping quarters in foreground. Open pit mine is partially visible in upper right hand corner. The 5,000,000 gallon water storage pond is in the upper center. The tailing area (not visible) is 1600-feet from the last thickener. The mill design and construction were by Stearns-Roger Manufacturing Company, who supplied the photos for this article.

The relatively recent discovery of significant uranium deposits in the Shirley Basin area of Wyoming enhanced Wyomings position as a major uranium producer. Extensive exploratory work starting early in 1957 confirmed the existence of substantial reserves in the Shirley Basin area and initiated the formation of the Petrotomics Company, a partnership consisting of Tidewater Oil Company, Kerr-McGee Oil Industries, Inc., Skelly Oil Company, and Getty Oil Company. The Tidewater Oil Company is the operating partner. Following the approval of an AEC milling contract, Petrotomics Company constructed a 500 ton per day acid leach-solvent extraction mill to process their Shirley Basin ores. Milling commenced April 5, 1962.

The topography of the mill site area is relatively flat and is at an elevation of 7,000 feet. Casper, Wyoming, is the nearest town of significant size and is approximately 40 airline miles north of the mill. The property is accessible by road from either Casper or Medicine Bow, Wyoming, on State Highway 487 and then 15 miles of dirt road off the highway.

nano wet ball mill, nano wet ball mill suppliers and manufacturers at

nano wet ball mill, nano wet ball mill suppliers and manufacturers at

A wide variety of nano wet ball mill options are available to you. You can also submit buying request for the abs sensor and specify your requirement on okchem.com, and we will help you find the quality nano wet ball mill suppliers.

There are a lot off suppliers providing nano wet ball mill on okchem.com, mainly located in Asia. The nano wet ball mill products are most popular in India, Pakistan, Vietnam, Indonesia, Brazil, Russia, Mexico, United States, Turkey, Germany, etc.

milling tests with the fritsch planetary ball mill

milling tests with the fritsch planetary ball mill

- Nanotechnology widely deals with nanoscale particle between 1-100 nm1. - Alternative definition of nano fertilizer (larger particle size): fertilizer which particle size is smaller than 500 mm and altered properties2. - Nanoparticles can be synthesized or produced by physical, chemical, biological and aerosol techniques. Physical synthesis methods include sedimentation processes, rotor speed mills, high energy ball mills and mixer mills. - In general, phosphorus (P) nanoparticles are prepared by purifying rock phosphate and grinding them with a high energy ball mill or mixer mill smaller than 500 nm and altered properties2. - This report describes the experimental trial and results of mineral fertilizer grinding using FRITSCH premium line Planetary Mills (High Energy Ball Mills) to obtain nanosize particles.

Fertilizer samples: There are two kind of mineral fertilizer obtained, processed and tested and comminuted using a high energy ball mill at the FRITSCH Laboratory in the - German Center, Singapore, which consisted of:

The laboratory mill used for the trials was the FRITSCH Planetary Micro Mill PULVERISETTE 7 premium line equipped with the following items: - Grinding Bowls (2 x 80 ml) - Grinding Balls (25 x 10 mm) - Grinding Balls (5 x 20 mm)

Grinding tests of the fertilizer samples using Planetary Mills were conducted at the FRITSCH office and laboratory of the German Center in Singapore. Mr. Diels Ding as an expert in grinding processes, as well as Business Manager for Asia Pacific Fritsch GmbH directly conducted the trials. He also provided informative insights and a meaningful discussion ensued about grinding and milling processes and nanomaterial. The samples were tested in dry and wet conditions for the milling process, with the following description:

2. What is the capacity of milling we want?The Planetary Mill PULVERISETTE 5 premium line provides two stations of grinding bowls with 500 ml volume (largest capacity on the market). Each grinding bowl can be filled 1/3 part of the volume ( 170 gr sample). So, if we use two grinding bowls, the optimum capacity is about 170 x 2 = 340 g per milling process.

4. How do we handle and apply the product of nano fertilizers into the field? If the milling process is successful in getting and achieving the targeted nano size fertilizer sample, then the next challenge is applying the product in the field properly and safely for humans and the environment.

About nanotechnology and nanomaterialOnly established companies apply the technology since the investment costs are substantial with high quality and precision of research, such as IT, energy, paint and the coatings industry etc.

ball mill, ball grinding mill - all industrial manufacturers - videos

ball mill, ball grinding mill - all industrial manufacturers - videos

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... LN2 feeding systems, jar and ball sizes, adapter racks, materials low LN2-consumption clearly structured user interface, memory for 9 SOPs programmable cooling and grinding cycles (10 ...

The XRD-Mill McCrone was specially developed for the preparation of samples for subsequent X-ray diffraction (XRD). The mill is used for applications in geology, chemistry, mineralogy and materials science, ...

The Planetary Ball Mill PM 200, engineered by Retsch, is a milling device best suited for mixing and size reduction processes and is also capable of meeting the necessary requirements for colloidal grinding ...

... Micro Mill PULVERISETTE 0 is the ideal laboratory mill for fine comminution of medium-hard, brittle, moist or temperature-sensitive samples dry or in suspension as well as for homogenising of emulsions ...

... , fast, effective. WORKING PRINCIPLE Impact and friction The FRITSCH Mini-Mill PULVERISETTE 23 grinds the sample through impact and friction between grinding balls and the inside wall of the grinding ...

... grinding mills includes being safe throughout. When the mills are quoted we make sure to include any and all safety components needed. Long life and minimum maintenance To help you get the most of your ...

Annular gap and agitator bead mills are used for processing suspensions and highly viscous products in chemicals and cosmetics as well as in the food sector. Studies have shown that annular gap bead ...

... Pneumatic extraction from the surface of the agitated media bed Wet grinding: Separation of suspension from the agitated media by ball retaining device Flexibility Through careful selection of the size and quantity ...

... details; Agitating power: 0,37 kW Total Power Consumption : 1.44 kW Total Weight : 100 kg Metal Ball Size : 6.35 mm Metal Ball Amount : 7 kg Cold water consumption : 10 liters / hour ...

Cement Ball Mill Processing ability: - 200 t/h Max feeding size: - 25 mm Product Fineness: - 0.074-0.89mm Range of application: - limestone, calcium carbonate, clay, dolomite and other minerals ...

... grinds and classifies a product. Vilitek MBL-NK-80 mill is specially designed for grinding valuable materials, which, when grinding, the re-milled fractions are not a commodity product. In particular, this mill ...

Dimensions: Height: 1530 mm Width: 650 mm Length : 1025 mm Description: Ball mills are capable of rapidly producing chocolate, nut pastes (for gianduia), and spreadable creams. It has been ...

ball mills - an overview | sciencedirect topics

ball mills - an overview | sciencedirect topics

A ball mill is a type of grinder used to grind and blend bulk material into QDs/nanosize using different sized balls. The working principle is simple; impact and attrition size reduction take place as the ball drops from near the top of a rotating hollow cylindrical shell. The nanostructure size can be varied by varying the number and size of balls, the material used for the balls, the material used for the surface of the cylinder, the rotation speed, and the choice of material to be milled. Ball mills are commonly used for crushing and grinding the materials into an extremely fine form. The ball mill contains a hollow cylindrical shell that rotates about its axis. This cylinder is filled with balls that are made of stainless steel or rubber to the material contained in it. Ball mills are classified as attritor, horizontal, planetary, high energy, or shaker.

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.

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 the movement of particles within the mill and contact zones of colliding balls.

By the rotation of the mill body, due to friction between the mill wall and balls, the latter rise in the direction of rotation until a helix angle does not exceed the angle of repose, whereupon the balls roll down. Increasing the rotation rate leads to the growth of the centrifugal force and the helix angle increases, correspondingly, until the component of the weight strength of balls becomes larger than the centrifugal force. From this moment, the balls are beginning to fall down, describing certain parabolic curves during the fall (Fig. 2.10).

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 remain attached to the wall with the aid of centrifugal force is:

where Dm is the mill diameter in meters. The optimum rotational speed is usually set at 65%80% of the critical speed. These data are approximate and may not be valid for metal particles that tend to agglomerate by welding.

where db.max is the maximum size of the feed (mm), is the compression strength (MPa), E is the modulus of elasticity (MPa), b is the density of material of balls (kg/m3), and D is the inner diameter of the mill body (m).

The degree of filling the mill with balls also influences the 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 30%35% of its volume.

The productivity of ball mills depends on the drum diameter and the relation of drum diameter and length. The optimum ratio between length L and diameter D, L:D, is usually accepted in the range 1.561.64. The mill productivity also depends on many other factors, including the physical-chemical properties of the feed material, the filling of the mill by balls and their sizes, the armor surface shape, the speed of rotation, the milling fineness, and the timely moving off of the ground product.

where D is the drum diameter, L is the drum length, b.ap is the apparent density of the balls, is the degree of filling of the mill by balls, n is the revolutions per minute, and 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, that is, during the grinding of material. Therefore, it is most disadvantageous to use a ball mill at less than full capacity.

Milling time in tumbler mills is longer to accomplish the same level of blending achieved in the attrition or vibratory mill, but the overall productivity is substantially greater. Tumbler mills usually are used to pulverize or flake metals, using a grinding aid or lubricant to prevent cold welding agglomeration and to minimize oxidation [23].

Cylindrical Ball Mills differ usually in steel drum design (Fig. 2.11), which is lined inside by armor slabs that have dissimilar sizes and form a rough inside surface. Due to such juts, the impact force of falling balls is strengthened. The initial material is fed into the mill by a screw feeder located in a hollow trunnion; the ground product is discharged through the opposite hollow trunnion.

Cylindrical screen ball mills have a drum with spiral curved plates with longitudinal slits between them. The ground product passes into these slits and then through a cylindrical sieve and is discharged via the unloading funnel of the mill body.

Conical Ball Mills differ in mill body construction, which is composed of two cones and a short cylindrical part located between them (Fig. 2.12). Such a ball mill body is expedient because efficiency is appreciably increased. Peripheral velocity along the conical drum scales down in the direction from the cylindrical part to the discharge outlet; the helix angle of balls is decreased and, consequently, so is their kinetic energy. The size of the disintegrated particles also decreases as the discharge outlet is approached and the energy used decreases. In a conical mill, most big balls take up a position in the deeper, cylindrical part of the body; thus, the size of the balls scales down in the direction of the discharge outlet.

For emptying, the conical mill is installed with a slope from bearing to one. In wet grinding, emptying is realized by the decantation principle, that is, by means of unloading through one of two trunnions.

With dry grinding, these mills often work in a closed cycle. A scheme of the conical ball mill supplied with an air separator is shown in Fig. 2.13. Air is fed to the mill by means of a fan. Carried off by air currents, the product arrives at the air separator, from which the coarse particles are returned by gravity via a tube into the mill. The finished product is trapped in a cyclone while the air is returned in the fan.

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).

Modern ball mills consist of two chambers separated by a diaphragm. In the first chamber the steel-alloy balls (also described as charge balls or media) are about 90mm diameter. The mill liners are designed to lift the media as the mill rotates, so the comminution process in the first chamber is dominated by crushing. In the second chamber the ball diameters are of smaller diameter, between 60 and 15mm. In this chamber the lining is typically a classifying lining which sorts the media so that ball size reduces towards the discharge end of the mill. Here, comminution takes place in the rolling point-contact zone between each charge ball. An example of a two chamber ball mill is illustrated in Fig. 2.22.15

Much of the energy consumed by a ball mill generates heat. Water is injected into the second chamber of the mill to provide evaporative cooling. Air flow through the mill is one medium for cement transport but also removes water vapour and makes some contribution to cooling.

Grinding is an energy intensive process and grinding more finely than necessary wastes energy. Cement consists of clinker, gypsum and other components mostly more easily ground than clinker. To minimise over-grinding modern ball mills are fitted with dynamic separators (otherwise described as classifiers or more simply as separators). The working principle is that cement is removed from the mill before over-grinding has taken place. The cement is then separated into a fine fraction, which meets finished product requirements, and a coarse fraction which is returned to mill inlet. Recirculation factor, that is, the ratio of mill throughput to fresh feed is up to three. Beyond this, efficiency gains are minimal.

For more than 50years vertical mills have been the mill of choice for grinding raw materials into raw meal. More recently they have become widely used for cement production. They have lower specific energy consumption than ball mills and the separator, as in raw mills, is integral with the mill body.

In the Loesche mill, Fig. 2.23,16 two pairs of rollers are used. In each pair the first, smaller diameter, roller stabilises the bed prior to grinding which takes place under the larger roller. Manufacturers use different technologies for bed stabilisation.

Comminution in ball mills and vertical mills differs fundamentally. In a ball mill, size reduction takes place by impact and attrition. In a vertical mill the bed of material is subject to such a high pressure that individual particles within the bed are fractured, even though the particles are very much smaller than the bed thickness.

Early issues with vertical mills, such as narrower PSD and modified cement hydration characteristics compared with ball mills, have been resolved. One modification has been to install a hot gas generator so the gas temperature is high enough to partially dehydrate the gypsum.

For many decades the two-compartment ball mill in closed circuit with a high-efficiency separator has been the mill of choice. In the last decade vertical mills have taken an increasing share of the cement milling market, not least because the specific power consumption of vertical mills is about 30% less than that of ball mills and for finely ground cement less still. The vertical mill has a proven track record in grinding blastfurnace slag, where it has the additional advantage of being a much more effective drier of wet feedstock than a ball mill.

The vertical mill is more complex but its installation is more compact. The relative installed capital costs tend to be site specific. Historically the installed cost has tended to be slightly higher for the vertical mill.

Special graph paper is used with lglg(1/R(x)) on the abscissa and lg(x) on the ordinate axes. The higher the value of n, the narrower the particle size distribution. The position parameter is the particle size with the highest mass density distribution, the peak of the mass density distribution curve.

Vertical mills tend to produce cement with a higher value of n. Values of n normally lie between 0.8 and 1.2, dependent particularly on cement fineness. The position parameter is, of course, lower for more finely ground cements.

Separator efficiency is defined as specific power consumption reduction of the mill open-to-closed-circuit with the actual separator, compared with specific power consumption reduction of the mill open-to-closed-circuit with an ideal separator.

As shown in Fig. 2.24, circulating factor is defined as mill mass flow, that is, fresh feed plus separator returns. The maximum power reduction arising from use of an ideal separator increases non-linearly with circulation factor and is dependent on Rf, normally based on residues in the interval 3245m. The value of the comminution index, W, is also a function of Rf. The finer the cement, the lower Rf and the greater the maximum power reduction. At C = 2 most of maximum power reduction is achieved, but beyond C = 3 there is very little further reduction.

Separator particle separation performance is assessed using the Tromp curve, a graph of percentage separator feed to rejects against particle size range. An example is shown in Fig. 2.25. Data required is the PSD of separator feed material and of rejects and finished product streams. The bypass and slope provide a measure of separator performance.

The particle size is plotted on a logarithmic scale on the ordinate axis. The percentage is plotted on the abscissa either on a linear (as shown here) or on a Gaussian scale. The advantage of using the Gaussian scale is that the two parts of the graph can be approximated by two straight lines.

The measurement of PSD of a sample of cement is carried out using laser-based methodologies. It requires a skilled operator to achieve consistent results. Agglomeration will vary dependent on whether grinding aid is used. Different laser analysis methods may not give the same results, so for comparative purposes the same method must be used.

The ball mill is a cylindrical drum (or cylindrical conical) turning around its horizontal axis. It is partially filled with grinding bodies: cast iron or steel balls, or even flint (silica) or porcelain bearings. Spaces between balls or bearings are occupied by the load to be milled.

Following drum rotation, balls or bearings rise by rolling along the cylindrical wall and descending again in a cascade or cataract from a certain height. The output is then milled between two grinding bodies.

Ball mills could operate dry or even process a water suspension (almost always for ores). Dry, it is fed through a chute or a screw through the units opening. In a wet path, a system of scoops that turn with the mill is used and it plunges into a stationary tank.

Mechanochemical synthesis involves high-energy milling techniques and is generally carried out under controlled atmospheres. Nanocomposite powders of oxide, nonoxide, and mixed oxide/nonoxide materials can be prepared using this method. The major drawbacks of this synthesis method are: (1) discrete nanoparticles in the finest size range cannot be prepared; and (2) contamination of the product by the milling media.

More or less any ceramic composite powder can be synthesized by mechanical mixing of the constituent phases. The main factors that determine the properties of the resultant nanocomposite products are the type of raw materials, purity, the particle size, size distribution, and degree of agglomeration. Maintaining purity of the powders is essential for avoiding the formation of a secondary phase during sintering. Wet ball or attrition milling techniques can be used for the synthesis of homogeneous powder mixture. Al2O3/SiC composites are widely prepared by this conventional powder mixing route by using ball milling [70]. However, the disadvantage in the milling step is that it may induce certain pollution derived from the milling media.

In this mechanical method of production of nanomaterials, which works on the principle of impact, the size reduction is achieved through the impact caused when the balls drop from the top of the chamber containing the source material.

A ball mill consists of a hollow cylindrical chamber (Fig. 6.2) which rotates about a horizontal axis, and the chamber is partially filled with small balls made of steel, tungsten carbide, zirconia, agate, alumina, or silicon nitride having diameter generally 10mm. The inner surface area of the chamber is lined with an abrasion-resistant material like manganese, steel, or rubber. The magnet, placed outside the chamber, provides the pulling force to the grinding material, and by changing the magnetic force, the milling energy can be varied as desired. The ball milling process is carried out for approximately 100150h to obtain uniform-sized fine powder. In high-energy ball milling, vacuum or a specific gaseous atmosphere is maintained inside the chamber. High-energy mills are classified into attrition ball mills, planetary ball mills, vibrating ball mills, and low-energy tumbling mills. In high-energy ball milling, formation of ceramic nano-reinforcement by in situ reaction is possible.

It is an inexpensive and easy process which enables industrial scale productivity. As grinding is done in a closed chamber, dust, or contamination from the surroundings is avoided. This technique can be used to prepare dry as well as wet nanopowders. Composition of the grinding material can be varied as desired. Even though this method has several advantages, there are some disadvantages. The major disadvantage is that the shape of the produced nanoparticles is not regular. Moreover, energy consumption is relatively high, which reduces the production efficiency. This technique is suitable for the fabrication of several nanocomposites, which include Co- and Cu-based nanomaterials, Ni-NiO nanocomposites, and nanocomposites of Ti,C [71].

Planetary ball mill was used to synthesize iron nanoparticles. The synthesized nanoparticles were subjected to the characterization studies by X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques using a SIEMENS-D5000 diffractometer and Hitachi S-4800. For the synthesis of iron nanoparticles, commercial iron powder having particles size of 10m was used. The iron powder was subjected to planetary ball milling for various period of time. The optimum time period for the synthesis of nanoparticles was observed to be 10h because after that time period, chances of contamination inclined and the particles size became almost constant so the powder was ball milled for 10h to synthesize nanoparticles [11]. Fig. 12 shows the SEM image of the iron nanoparticles.

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.

In spite of the traditional approaches used for gas-solid reaction at relatively high temperature, Calka etal.[58] and El-Eskandarany etal.[59] proposed a solid-state approach, the so-called reactive ball milling (RBM), used for preparations different families of meal nitrides and hydrides at ambient temperature. This mechanically induced gas-solid reaction can be successfully achieved, using either high- or low-energy ball-milling methods, as shown in Fig.9.5. However, high-energy ball mill is an efficient process for synthesizing nanocrystalline MgH2 powders using RBM technique, it may be difficult to scale up for matching the mass production required by industrial sector. Therefore, from a practical point of view, high-capacity low-energy milling, which can be easily scaled-up to produce large amount of MgH2 fine powders, may be more suitable for industrial mass production.

In both approaches but with different scale of time and milling efficiency, the starting Mg metal powders milled under hydrogen gas atmosphere are practicing to dramatic lattice imperfections such as twinning and dislocations. These defects are caused by plastics deformation coupled with shear and impact forces generated by the ball-milling media.[60] The powders are, therefore, disintegrated into smaller particles with large surface area, where very clean or fresh oxygen-free active surfaces of the powders are created. Moreover, these defects, which are intensively located at the grain boundaries, lead to separate micro-scaled Mg grains into finer grains capable to getter hydrogen by the first atomically clean surfaces to form MgH2 nanopowders.

Fig.9.5 illustrates common lab scale procedure for preparing MgH2 powders, starting from pure Mg powders, using RBM via (1) high-energy and (2) low-energy ball milling. The starting material can be Mg-rods, in which they are processed via sever plastic deformation,[61] using for example cold-rolling approach,[62] as illustrated in Fig.9.5. The heavily deformed Mg-rods obtained after certain cold rolling passes can be snipped into small chips and then ball-milled under hydrogen gas to produce MgH2 powders.[8]

Planetary ball mills are the most popular mills used in scientific research for synthesizing MgH2 nanopowders. In this type of mill, the ball-milling media have considerably high energy, because milling stock and balls come off the inner wall of the 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.

In the typical experimental procedure, a certain amount of the Mg (usually in the range between 3 and 10g based on the vials volume) is balanced inside an inert gas atmosphere (argon or helium) in a glove box and sealed together with certain number of balls (e.g., 2050 hardened steel balls) into a hardened steel vial (Fig.9.5A and B), using, for example, a gas-temperature-monitoring system (GST). With the GST system, it becomes possible to monitor the progress of the gas-solid reaction taking place during the RBM process, as shown in Fig.9.5C and D. The temperature and pressure changes in the system during milling can be also used to realize the completion of the reaction and the expected end product during the different stages of milling (Fig.9.5D). The ball-to-powder weight ratio is usually selected to be in the range between 10:1 and 50:1. The vial is then evacuated to the level of 103bar before introducing H2 gas to fill the vial with a pressure of 550bar (Fig.9.5B). The milling process is started by mounting the vial on a high-energy ball mill operated at ambient temperature (Fig.9.5C).

Tumbling mill is cylindrical shell (Fig.9.6AC) that rotates about a horizontal axis (Fig.9.6D). Hydrogen gas is pressurized into the vial (Fig.9.6C) together with Mg powders and ball-milling media, using ball-to-powder weight ratio in the range between 30:1 and 100:1. Mg powder particles meet the abrasive and impacting force (Fig.9.6E), which reduce the particle size and create fresh-powder surfaces (Fig.9.6F) ready to react with hydrogen milling atmosphere.

Figure 9.6. Photographs taken from KISR-EBRC/NAM Lab, Kuwait, show (A) the vial and milling media (balls) and (B) the setup performed to charge the vial with 50bar of hydrogen gas. The photograph in (C) presents the complete setup of GST (supplied by Evico-magnetic, Germany) system prior to start the RBM experiment for preparing of MgH2 powders, using Planetary Ball Mill P400 (provided by Retsch, Germany). GST system allows us to monitor the progress of RBM process, as indexed by temperature and pressure versus milling time (D).

The useful kinetic energy in tumbling mill can be applied to the Mg powder particles (Fig.9.7E) by the following means: (1) collision between the balls and the powders; (2) pressure loading of powders pinned between milling media or between the milling media and the liner; (3) impact of the falling milling media; (4) shear and abrasion caused by dragging of particles between moving milling media; and (5) shock-wave transmitted through crop load by falling milling media. One advantage of this type of mill is that large amount of the powders (100500g or more based on the mill capacity) can be fabricated for each milling run. Thus, it is suitable for pilot and/or industrial scale of MgH2 production. In addition, low-energy ball mill produces homogeneous and uniform powders when compared with the high-energy ball mill. Furthermore, such tumbling mills are cheaper than high-energy mills and operated simply with low-maintenance requirements. However, this kind of low-energy mill requires long-term milling time (more than 300h) to complete the gas-solid reaction and to obtain nanocrystalline MgH2 powders.

Figure 9.7. Photos taken from KISR-EBRC/NAM Lab, Kuwait, display setup of a lab-scale roller mill (1000m in volume) showing (A) the milling tools including the balls (milling media and vial), (B) charging Mg powders in the vial inside inert gas atmosphere glove box, (C) evacuation setup and pressurizing hydrogen gas in the vial, and (D) ball milling processed, using a roller mill. Schematic presentations show the ball positions and movement inside the vial of a tumbler mall mill at a dynamic mode is shown in (E), where a typical ball-powder-ball collusion for a low energy tumbling ball mill is presented in (F).

wet ball mill for metal ores and non-ferrous metals wet milling

wet ball mill for metal ores and non-ferrous metals wet milling

Applications: It can deal with metal and non-metal ores, including gold, silver, copper, phosphate, iron, etc. The ore that needs to be separated and the material that will not affect the quality of the final product when encountering water.

Wet ball mill is a kind of equipment which uses grinding medium and a certain amount of liquid (water or anhydrous ethanol) to grind materials. Unlikedry ball mill, wet ball mill adopts the wet grinding method.

The characteristic of wet grinding is that the material needs to be soaked in the liquid for grinding. This method can effectively reduce the chance of the material properties changing due to the temperature increase during the grinding process.

In the process of grinding, due to the different grinding materials, a proper amount of water or anhydrous ethanol will be added to the wet grinding ball mill. Steel ball and liquid participate in the grinding process together. The common ratio of steel ball, material and water in the wet grinding mill is 4:2:1. Depending on the nature of the grinding material, the actual ratio will be adjusted, and the specific ratio needs to be determined through the beneficiation test.

The working principle of the wet ball mill is basically the same as that of the dry ball mill. Both the rotation of the barrel drives the grinding medium and the material in the barrel to move together, and the purpose of grinding the material is finally achieved through the action of dropping and squeezing.

With the continuous feeding of materials, the generated pressure forces the materials that are fed first and have reached the qualified particle size to move to the discharge port of the wet grinding mill. The discharge port of the wet grinding ball mill is of the trumpet type, with a built-in screw device. The water flows out along the screw device, and the qualified materials are taken out of the ball mill at the same time.

Because there is liquid involved in the grinding process, the wet grinding mill will not produce dust during the work process, so there is no need to add other auxiliary equipment. According to the different discharging methods, wet ball mill can be divided into overflow type andgrate type ball mill. Wet grinding ball mill is suitable for the treatment of materials with high moisture content, most of the ore will not produce physical or chemical reaction when encountering water, so it is also suitable for wet grinding.

As a ball mills supplier with 22 years of experience in the grinding industry, we can provide customers with types of ball mill, vertical mill, rod mill and AG/SAG mill for grinding in a variety of industries and materials.

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