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.
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Address No.11 West Construction Road, Zhongyuan District,Zhengzhou City,Henan Province, China
what are the differences between dry and wet type ball mill? | fote machinery
The ball mill is a kind of grinding machine, which is the key milling machine used after the material has been crushed, and it also has a mixing effect. This type of grinding machine has a cylindrical body with spherical grinding mediums and materials.
The centrifugal force and friction generated by the rotation of the fuselage bring the material and the grinding medium to a certain height and then fall. Impact and friction grind the material into fine powders.
It is widely used in cement, silicate, new construction material, refractory material, chemical fertilizer, ferrous metal and non-ferrous as well as ceramics, and widely applied to dry or wet grinding for ores and grindable materials. The wet type is often equipped with a classifier, and the dry type is configured with a suction and separation device.
Both of the dry and wet ball mills are composed of feeding port, discharging port, turning part, and transmission parts such as retarder, small transmission gear, motor, electronic control. The wet grinding can be widely used, because most of the minerals can be wet milled.
The ball mill is equipped with a cylindrical rotating device and two bins, which can rotate by gears. The discharge port is straight, and there are also air intake devices, dust exhaust pipes, and dust collectors.
The material from the feeding device is uniformly fed into the first bin of the mill by the hollow shaft spiral. This bin has stepped lining or corrugated lining, which is filled with steel balls of different specifications.
The rotation of the cylinder generates centrifugal force to bring the steel ball to a certain height, and then fall, which will hit and grind the material. After the material is coarse grinding in the first bin, it will enter the second bin through the single-layer partition plate.
This bin is embedded with a flat liner, and the steel balls inside will further grind the material, then the powder is discharged through the discharge grate to complete the grinding. We can't add water or other liquids during the grinding process.
The material needs to be added water or anhydrous ethanol during the grinding process. We must control the grinding concentration, otherwise, it will affect the grinding efficiency. The amount of water depends on the use of the mud, the amount of clay in the formula, and the water absorption of the clay.
It will be gradually pulverized under the action of impact and grinding. The movement of the ore needs to be driven by the water. The bulk material will be cracked under the impact and grinding of the grinding medium, with the crack gradually increasing and deepening, the final material will be separated from the crack to achieve the effect of bulk material being ground.
The grinding ore will be discharge through the discharge port, and then the discharged mineral will be classified into the qualified product in a spiral classifier, with the coarse sand being returned to the ball mill through the combined feeder to continue grinding.
The feeder feeds material continuously and evenly, the ground material will be continuously discharged from the ball mill. The wet ball mill can be divided into three types according to the motion characteristics: a simple swing type wet ball mill, a complex swing type wet ball mill, and a hybrid swing type wet ball mill.
The dry grinding is suitable for materials that can react with water, which may not be used for wet grinding such as cement, marble and other building materials. Some products which require storage and sale in powder form is suitable for dry grinding, and in some other arid areas, because of the lack of water resources, dry grinding can also be used to save water.
Wet grinding is suitable for most materials, such as all kinds of metal ore, non-metallic ore. As long as it is water-repellent and will not affect the quality of the finished product, the material can be used for wet grinding.
Common ore includes copper ore, iron ore, molybdenum ore, phosphate rock, feldspar mine, fluorite ore, etc. The proportion of steel balls, materials, and water in wet grinding is 4:2:1. The detailed proportion can be determined by grinding experiments.
At the same time, the size of the alumina grinding balls is also required. If the ratio is good, then the ball milling efficiency will be greatly improved. Generally, there are large, medium and small balls, and the better ratio between them can also be obtained through experiments.
The dry milling process may be used when the particle size of the powder is not required to be very fine or when the ball milled product is to be stored or sold in powder form. For example, in the production of cement, it is necessary to choose dry grinding instead of wet grinding, otherwise, it will be difficult to meet our needs.
Wet grinding is generally used in mineral processing, because the wet ball mill has the advantages of strong materials adaptability, continuous production, large grinding ratio, easy to adjust the fineness of the milled products, and it is widely used at present.
Since the dry and wet ball mill equipment has its own advantages, we must find out the suitable grinding type that the material is suitable for so that we can ensure quality and efficiency. Welcome to consult Fote company, where our professionals will give you a satisfactory answer based on your needs.
As a leading mining machinery manufacturer and exporter in China, we are always here to provide you with high quality products and better services. Welcome to contact us through one of the following ways or visit our company and factories.
Based on the high quality and complete after-sales service, our products have been exported to more than 120 countries and regions. Fote Machinery has been the choice of more than 200,000 customers.
trommel scrubber | gold trommel washing plant - jxsc machine
Capacity Up to 200 TPH Function gold trommel scrubber can effectively wash and sieve ore material which contains sticky clay, mud, prevents clogging. Models & TypesFixed type and portable type Application gold dredger, quartz mine, limonite ore, nonferrous ore, construction use sand and gravel washing, etc.
DescriptionGold trommel scrubber, also known as rotary screen ore washer, orcylinder screen washer, it is a multi-purpose hydraulic cleaning soil, sticky mud equipment which is both have cleaning function and a screening function. That is, the trommel scrubber machine not only can preliminary clean the raw materials but also sieves them by particles. The trommel washing machine is placed before a crusher, gravity separator, magnetic separator, and flotation to avoid clogging and improve beneficiation efficiency. Feeding materialParticle size up to 200-300mm, mud content greater than 20%. Discharge materialThe gold trommel scrubber washing machine does washing and grading in one time, and divide the material into +40mm and -40mm; use double spiral groove type washer to further clean and grade the -40mm material into +2mm and -2mm product. Screen meshmesh size 8 50mm. Screen material: PU or manganese or stainless steel, 1 layer, 2 layers. Liner platenatural rubber, spiral welded steel plate. Features(1) Trommel scrubber with a good function of washing and screening. (2) High production capacity (can be from 1T/H to 250 T/H). (3) Low operating costs, easy maintenance, and low noise. (4) The length diameter of the drum, screen mesh, mesh layer, liner plate, portable or stationary, drive tire material are customizable. Small scale gold wash plants, mini gold trommel are available. (5) With Rubber tires driving, water spray pipes inside the screen. Gold trommel price affected by the material of trommel screen, liner plate (eg. natural rubber or used rubber), motor power and brand (Siemens), reducer (K series), tire (natural rubber pneumatic tire), trommel thickness, electrical cabinet (variable frequency), etc. JXSC has an unrivaled price of the gold trommel and trommel wash plant, contact us for the 12hrs quotation, and processing flow design & optimization service.
Main partsTrommel scrubber washer machine with two parts: drum scrubber and screen. The drum scrubber is for washing ore, the screen is for sieving different size particles after washing. Work Principle of Gold Trommel A high-pressure flushing water pipe is arranged in the longitudinal direction of the cylinder. The rotation of the cylinder screen causes the ore to turn over and collide with each other, and with the hydraulic scouring, the clay is broken and cleaned. The washing effect increases with the residence time of the ore in the return screen, the water pressure of the spray water and the water consumption. In order to strengthen the mechanical action of the equipment, longitudinal steel bars for loose ore can be installed on the inner wall of the cylindrical sieve.
1. Prevent clogging: ore with more mud is easy to cause clogging of ore bin, chute, crushing and screening equipment. 2. Concentrate enrichment: ore washer can gather some value minerals, such as manganese ore, apatite ore, iron oxide; 3. Improve product quality: washing machine remove the slime, improves the smelting uses limestone quality. Gold trommel manufacturerGold Mining Equipment such as our gold trommel has hardened bolt in wear plates, oversized shafts and bearings, polygon drums, high tensile frames, and quick change urethane screens. JXSC gold equipment provider, professional gold trommel design service, gold trommel for sale!
wet grid ball mill
Grid ball mill is widely used in smashing all kinds of ores and other materials, ore dressing and national economic departments like building and chemical industries etc. The size of ore shall not exceed 65mm and the best feed size is under 6mm. The effect in this job is better than coarse grinding. Grid ball mill consists of the shell, feeding part, discharging part, main bearing, lubricating system, driving system and other parts. There is wearing a liner inside the shell, and both ends of the shell are provided with a flange. The end cover of the mill is connected with the flange plate. The feeding part consists of the head, trunnion and feeding device. The discharge part includes the grid plate, head, and discharge trunnion.
Wet Grid ball mill is mainly used for mixing and grinding materials in two types: dry grinding and wet grinding .It has advantages of fineness uniformity and power saving. The machine uses different types of liner to meet different customer needs. The grinding fineness of material can be controlled by grinding time. The electro-hydraulic machine is auto-coupled and decompressed to reduce the starting current, and its structure is divided into integral type and independent type.
Compared with similar products,Wet Grid ball mill has the characteristics of low investment, low energy consumption, novel structure, simple operation, stable and reliable performance. It is suitable for mixing and grinding ordinary and special materials. The users can choose the right type, liner and medium type by considering the specific gravity, hardness, yield and other factors. The grinding medium is Wet Grid ball.
1.The ball mill is composed of a horizontal cylinder, a hollow shaft for feeding and discharging, and a grinding head. The main body is a long cylinder made of steel. The cylinder is provided with an abrasive body, and the steel lining plate is fixed to the cylinder body. The grinding body is generally a steel ball and is loaded into the cylinder according to different diameters and a certain proportion, and the grinding body can also be used with a steel section.
2.According to the particle size of the grinding material, the material is loaded into the cylinder by the hollow shaft of the wet grid ball mill feeding end. When the ball mill cylinder rotates, the grinding body acts on the cylinder liner due to the action of inertia and centrifugal force and friction. It is carried away by the cylinder. When it is brought to a certain height, it is thrown off due to its own gravity. The falling abrasive body crushes the material in the cylinder like a projectile.
3.The material is uniformly fed into the first chamber of the mill by the feeding device through the hollow shaft of the feeding material. The chamber has a step liner or a corrugated liner, and various steel balls are loaded therein. The rotation of the cylinder generates centrifugal force to bring the steel ball to a certain extent. The height drops and then hits and grinds the material. After the material reaches the rough grinding in the first bin, it enters the second bin through the single-layer partition plate. The bin is embedded with a flat liner with steel balls inside to further grind the material. The powder is discharged through the discharge raft to complete the grinding operation.
The main function of the steel ball in the ball mill is to impact crush the material and also play a certain grinding effect. Therefore, the purpose of grading steel balls is to meet the requirements of these two aspects. The quality of the crushing effect directly affects the grinding efficiency, and ultimately affects the output of the ball mill. Whether the crushing requirement can be achieved depends on whether the grading of the steel ball is reasonable, mainly including the size of the steel ball, the number of ball diameters, and the ball of various specifications. Proportion and so on.
The ball mill is composed of the main part such as a feeding part, a discharging part, a turning part, a transmission part (a reduction gear, a small transmission gear, a motor, and electric control). The hollow shaft is made of cast steel, the inner lining can be replaced, the rotary large gear is processed by casting hobbing, and the barrel is embedded with wear-resistant lining, which has good wear resistance. The machine runs smoothly and works reliably.
The Steel Head Rod Mill(sometimes call a bar mill)gives the ore dressing engineer a very wide choice in grinding design. He can easily secure a standard Steel Head Rod Mill suited to his particular problem. The successful operation of any grinding unit is largely dependent on the method of removing the ground pulp. The Steel Head Rod Mill is available with five types of discharge trunnions and each type trunnion is available in small, medium, or large diameter. The types of Rod Mill discharge trunnions are:
The superiority of the Steel Head Rod Mill is due to the all-steel construction. The trunnions are an integral part of the cast steel heads and are machined with the axis of the mill. The mill heads are insured against breakage due to the high tensile strength of cast steel as compared to that of the cast iron head found on the ordinary rod mill. Trunnion Bearings are made of high-grade nickel babbitt, dovetailed into the casting. Ball and socket bearings can be furnished if desired.
Head and shell liners for Steel Head Rod Mills are available in Decolloy (a chrome-nickel alloy), hard iron, electric steel, molychrome steel, and manganese steel. The heads have a conical shaped head liner construction, both on the feed and discharge ends, so that there is ample room for the feed from the trunnion helical conveyor discharge to enter the mill betweenthe rods and head liners on the feed end of the mill. Drive gears are furnished either in cast tooth spur gear and pinion or cut tooth spur gear and pinion. The gears are furnished as standard on the discharge end of the mill, out of the way of the classifier return feed, but can be furnished at the mill feed end by request. Drives may be obtained according to the customers specifications.
The following table clearly illustrates why Steel Head Rod Mills have greater capacity than other mills. This is due to the fact that the diameters are measured inside the liners, while other mills measure their diameter inside the shell.
Rod Mills may be considered either fine crushers or coarse grinding equipment. They are capable of taking as large as 2 feed and making a product as fine as 35-48 mesh. Of particular advantage is their adaptability to handling wet sticky ores, which normally would cause difficulty in crushing operations. Under wet grinding conditions of course the problem of dust is eliminated.
The grinding action of a rod mill is line contact. As material travels from the feed end to the discharge end it is subjected to crushing forces inflicted by the grinding rods. The rods both tumble in essentially a parallel alignment and also spin, thus simulating the crushing and grinding action obtained from a series of roll crushers. The large feed tends to spread the rods at the feed end which imparts still an additional action which may be termed scissoring. As a result of this spreading the rods tend to work on the larger particles and thereby produce a minimum amount of extremely fine material.
The Rod Mill encourages the use of a thick pulp coating both the liners and the rods, thus minimizing steel consumption. Continuous movement of the pulp through the rod mass eliminates the possibility of short circuiting any material. The discharge end of the Rod Mill is virtually open and larger in diameter than the feed end, providing a steep gradient of material flow through the mill. This is described in more detail on pages 20 and 21.
Normally Rod Mills are furnished of the two trunnion design. For special applications they may be furnished of the tire trunnion or two- tire construction. These mills can be equipped with any type of feeder and type of drive, discussed separately in this catalog.
The above tables list some of the most common Open End Rod Mill sizes. Capacities are based on medium hard ore with mill operating in closed circuit under wet grinding conditions at speeds indicated. For dry grinding, speeds and power are reduced and capacities drop 30 to 50%.
The End Peripheral Discharge Rod Mill is designed to produce a minimum amount of fines when grinding either wet or dry. Material to be ground enters through a standard trunnion and is discharged through port openings equally spaced around the mill periphery. These ports are in a separate ring placed between the shell and the discharge head.
The construction of the end peripheral discharge mill emphasizes the principle of grinding. Due to the steep gradient between the point of entry and the point of discharge the pulp flows rapidly through the mill providing a fast change of mill content with a relatively small amount of pulp within the grinding chamber.
The sloping or conical shaped feed head proves ample space for a feed pocket to accommodate large quantities of material and assure their entrance into the grinding rods. Any type of feeder listed on pages 22 and 23 can be furnished for these mills; however, since the mills are not usually operated in closed circuit grinding, the drum or spout feeder is normally preferred.
No other type of mill is so well adapted to dry grinding materials to -4 or -8 mesh in single pass with the production of a minimum amount of fines. A major factor in dry grinding is the rapid removal of finished material to prevent cushioning of the rods. This is accomplished in the End Peripheral Discharge Rod Mill.
The free discharge feature permits the grinding of material having a higher moisture content than with other types of rod or ball mills. Our Peripheral Discharge Mills have found wide application in grinding coke and friable non-metallics, material for glass, pyroborates, as well as gravel to produce sand. Another application is for grinding and mixing sand lime brick materials. The rod action gives a thorough mixture while grinding of the hydrated lime and sand.
For specifications of End Peripheral Discharge Rod Mills use table of standard open end rod mills given on pages 24 and 25. The capacity of the end peripheral discharge rod mill is slightly higher than shown for the Open End Rod Mills.
The CPD (Center Peripheral Discharge) Rod Mill has been developed to produce sand to meet U. S. Government or State specifications. It has also found application in grinding friable non-metallics, and industrial materials and ores which tend to slime excessively. Another application is in the field of abrasion milling on ores such as found on the Mesabi Iron Range. In this latter application true grinding is not desired, but more of a surface scrubbing of the individual particles.
Again with this construction grinding may be done either wet or dry. In this design, however, feed enters both ends by means of feeders and is discharged at the center through rectangular discharge ports equally spaced around the mill periphery. The center discharge openings are generally contained in a separate ring placed between shell halves. The ground material is discharged and directed to either side or directly under the mill by the use of a discharge ring housing.
In standard rod-milling it will be found that rods spread apart at the feed end in the amount of the maximum size of feed entering the mill. In the center peripheral discharge mill the rods are spread at both ends and parallel throughout the length of the mill. This feature results in more space between the rods and thereby lessens the amount of fines produced. Furthermore, fines are also diminished because the material moves rapidly through the mill due to the steep gradient of travel and the distance of travel is reduced by half. Similarly time of contact with the grinding media is reduced by half.
Another center peripheral discharge advantage is that a cubical shaped particle is produced. Maintenance is negligible and grinding media is relatively inexpensive. Other types of sand manufacturing equipment lose efficiency with wear and require excessive maintenance. This loss of efficiency increases rapidly as hardness of feed increases. The Center Peripheral Discharge Rod Mill can be easily maintained at peak operating efficiency by the periodical addition of rods. CPD Rod Mills give a wide range of flexibility to sand plant operation. By changing the rate of feed, pulp dilution (wet grinding), and discharge port area it is possible to produce and blend sand of virtually any fineness modulus and maintain it within Government specifications.
Unlike many crushers or grinders the CPD Mill can easily handle wet or sticky material. When grinding wet, the dust nuisance is completely eliminated. For dry grinding applications the mill is furnished with a dust proof discharge housing.
Various items must be considered in computing the cost of producing manufactured sand. These include wear on the constituent parts, power consumption, lubrication, labor and general maintenance. Maintenance of the center peripheral discharge mill is definitely much lower than that of any other sand manufacturing machine. The greater portion of the wear which takes place is on the inexpensive high carbon steel rods. Field installations show an average of less than 1 # per ton of sand ground as rod consumption, and from 0.08# to 0.10# per ton of sand ground as the steel liner wear. The overall cost of mill operation, exclusive of amortization, is generally less than 30c per ton (year 1958).
Every possible operating convenience has been incorporated in the center peripheral discharge mill design. On most sizes the trunnions are carried in large lead bronze bushed bearings. The interior of the mill is readily accessible through these large trunnion openings. The peripheral ring housing is furnished with a door for inspection and another lower door to facilitate sampling of the mill discharge. Covers for the discharge ports are furnished allowing any variation in discharge area which might be desired.
Given below are approximate capacities for several sizes of the center peripheral discharge mills. Such capacities are expressed in dry tons per hour, based on - x 4 mesh screened feed of medium hard gravel. Mill discharge is generally less than 5% + 4 mesh in wet open circuit operations, for dry grinding work reduce the capacities indicated by approximately 30% to 50%.
A Rod Mill has for Working Principle its inside filledgrinding media, in this case STEEL RODS. These rods run the length of the machine, which is most commonly between eight and sixteen feet in length. The diameter of these rods will range from, when new, between two and four inches. The rods arefree inside the mill. When the mill is turned, the rods tumble against one another grinding all the ore that is between them to aid in the grinding, water is added with the ore as it enters the mill.So from that you can see why it is called a wet tumbling mill. The ore is ground wet and the mill revolves. This causes the grinding media inside of it to tumble grinding the ore.
Historically there has been three basic ways of grinding ore, hammer mills, rolls, or wet tumbling mills. Hammer mills and rolls are not used that often and then usually only for special applications as in lab work or chemical preparation.
The type of mill that is used for grinding ore in a modern concentrator is the wet tumbling mill. These mills may be divided into three types ROD MILLS, BALL MILLS andAUTOGENOUS MILLS. In the first type, the ROD MILL, the ore is introduced into the mill.
From the trunnion liner out wards first we will come to the FACE PLATE. It is slightly concave to create the POOLING AREA for the rock to collect in before entry to the ROD-LOAD. On the outside attached to the face plate is the BULL GEAR. This gear completely circles the mill and provides the interface between the motor and the mill. The bull gear and drive line may be at the other end of the mill instead. There are advantages and disadvantages to either end this will be explained later when we are discussing the motor and drive line. But for now back to the face plate, attached to the other side of the face plate is the SHELL. The shell is the body of the mill. On the inside of the mill there are two layers of material, the first layer is the BACKING for the liners. This is customarily constructed from rubber but wood may be used as well. The purpose of this backing is two-fold, one to absorb the shock that is transmitted through the liners from normal running. And to provide the shell with a protective covering to eliminate the abrasion that is produced by the finely ground rock and water. Without this rubber or wood backing, the life of the mill is drastically reduced due to metal fatigue and simply being worn away.For those of you arent familiar with METAL FATIGUE I will explain. When metal is continually pounded or vibrated, the molecular structure of the metal begins to change, it is said to CRYSTALLIZE, and the metal becomes hard and finally loses all ability to give with the vibration. Thousands of microscopic cracks will begin to appear, as the fatigue of the metal continues, these cracks will grow to become major problems.
Later for interest sake we will explain the difference in some of them, but for now lets stay with identifying the parts of the mill. We have already mentioned the trunnion liner so let start from there.
The trunnion liner may also be referred to as the THROAT LINER. You will find that many of these parts will be called two or even sometimes three names, All I can say is try not to let it confuse you, The name isnt as important as the job that it does. As long as everybody that you work with agree on which name to use, it doesnt matter that much.
Next to this liner is the END LINERS, or to some, the PACE PLATE LINERS.The FILLER RING which is next is not standard in all mills, some mills have them, and some dont. Their job is to fill the corner of the mill up so the shell will not wear at that point. They dont provide any lift to the media, in fact quite often the media will not come into contact with them at all, but what they do is make changing liners that much easier. With different liner designs the replacement of a single liner may be quite difficult and to change one could become a lengthy project.
The liner that butts into the filler liner is known as a BELLY LINER or SHELL LINER, and in some designs LIFTER BARS. These liners and/or lifters give the media its CASCADING action and also receive the most wear. They cover the complete body of the mill and have the largest selection of types to choose from.
As the two ends of the mill are the same there isnt any reason to go over the other face plate. The discharge trunnion assembly is very much like the feed trunnion except that, it wont have a worm as part of the liner. Instead of a feed seal bolted to it, it may have a screen.
This is called a TRUMMEL SCREEN and its purpose is to screen out any rock that didnt get ground as well as any TRAMP METAL or REJECT STEEL that may be coming out of the mill. Reject steel is the old grinding media that has been worn so small that it comes out of the mill. If this tramp metal and steel is allowed to get into pumps and classifiers damage and plug- ups may be caused.
With regards to Rod Mills, let us start by identifying the different portions of the rod load as it goes through one revolution, as you will see, each of these areas will hold interest for the Grinding operator.
As the rod mill turns, the rods are carried by the lifting portion of the liners. The height that they are lifted is referred to as the lift of the liners. As they roll off of the liners, the rods enter the cascade zone. The rods roll through the cascade zone until they come to the toe of the load. At this point the rods come to rest in relation to the shell of the mill. The liners lift the rods back to begin the cascade again. You will notice, that as you go deeper into the rod load, the rod movement becomes less and less until the movement is very slight at the deepest part. This area is called the core of the load. As a description of the normal grinding action, the rods and the ore react together like this. The ore enters-the mill and is deposited in the pooling area directly under the feed trunnion.
This pooling area allows the large rock to fall towards the outside portion of the load, the TOE area. This is the zone with the greatest movement in it, which means the area that will have the highest impact on the ore.
The rock will be carried up by the rods as they go through the CASCADE ZONE reducing the size of the rock. As each particle of ore becomes smaller it will work towards the CORE ZONE while travelling the length of the mill. That makes for a rather neat arrangement doesnt it. The larger rock is deposited in the area where the maximum impact from the rod load occurs and then as each particle gets smaller it slowly travels inwards towards the centre of the load.
This is where the maximum surface contact takes place, producing the finer grind. When the ore has travelled from one end of the mill to the other end it will have completed its grinding cycle in this mill. As it exits the rod load it will be deposited in another POOLING AREA prior to leaving the mill by way of the DISCHARGE TRUNNION.
Prom that you can see how a mill will become over loaded. If for some reason the rock begins to separate the rods over their entire length, the larger rock will prevent the intermediate rock from being ground. Which in turn will begin to invade the area that the fine material is being ground in. As the rods become separated through the entire load, the grind will get progressively worse until the unground rock is in the discharge pooling area. At this point, the operator will notice, that large rock is being discharged from the discharge trunnion.
During normal operations there is usually a certain amount of this larger rock that wont get ground. These are known as REJECTS and they serve as one of the tattle tales as to how the mill is grinding. If there is an increase of these rejects then the mill isnt grinding that well and the operator will have to do something about it. If he doesnt the mill load will continue to climb, until the rods in the lifting zone are completely separated. When this happens those rods will have quit grinding.
There is a visual warning of this happening that the operator can take advantage of. The lift on the rods will get higher and higher until they are being carried to the very top of the mill before cascading. I think falling would be a better word for it though.
As this is happening, the core of the load will be slowly moving away from the shell towards the center of the mill. This is because the volume of the mill is being filled with unground rock. This will continue until the load hits a critical volume and a critical density. The rock still coming in to the mill will have to have some where to go so it tries pushing the rods out of the mill. Unfortunately they wont make it, the first hunch of rods that get far enough into the discharge trunnion will be- hit by the rest of the load bending and twisting them until they look like SPAGHETTI. This usually shuts the mill down for a couple of days while the millwrights cut the bent rods out of the mill.
On the other end of the scale, if the density is to light, the rod load will become too active, not having the solids in the mill to cushion the impact of rod on rod and rod on liner. As the rods enter the cascade zone, the pattern of the movement of the rods will be different. Instead of having a tightly tumbling mass of rods, the rods will be separated. The lift will be higher and the cascade will form more of an arc. The impact of the rods on the rock will be less because there will be more give in the rod load, with high amount of steel on steel causing the rods to bounce.
Letslook at how these Rod mills work, as I mentioned earlier there are steel rods inside the mill, it is their job to do the actual grinding. If you look at the mill in a cross section of an end view. You will get a very good illustration of the grinding action, of the mill.
The LINERS provide the tumbling action of the rods. When the mill rotates the rods are lifted until they roll off of the liners, this is known as CASCADING. The ore enters the mill at the feed end, as the rods cascade and tumble, the rock is caught between the rods and is ground. The size that the rock will be ground to is dependent on the amount of time the ore is in the mill, how many rods there are in the mill V and the size of the incoming ore.
Our automatic production line for the grinding cylpebs is the unique. With stable quality, high production efficiency, high hardness, wear-resistant, the volumetric hardness of the grinding cylpebs is between 60-63HRC,the breakage is less than 0.5%. The organization of the grinding cylpebs is compact, the hardness is constant from the inner to the surface. Now has extensively used in the cement industry, the wear rate is about 30g-60g per Ton cement.
Grinding Cylpebs are made from low-alloy chilled cast iron. The molten metal leaves the furnace at approximately 1500 C and is transferred to a continuous casting machine where the selected size Cylpebs are created; by changing the moulds the full range of cylindrical media can be manufactured via one simple process. The Cylpebs are demoulded while still red hot and placed in a cooling section for several hours to relieve internal stress. Solidification takes place in seconds and is formed from the external surface inward to the centre of the media. It has been claimed that this manufacturing process contributes to the cost effectiveness of the media, by being more efficient and requiring less energy than the conventional forging method.
Because of their cylindrical geometry, Cylpebs have greater surface area and higher bulk density compared with balls of similar mass and size. Cylpebs of equal diameter and length have 14.5% greater surface area than balls of the same mass, and 9% higher bulk density than steel balls, or 12% higher than cast balls. As a result, for a given charge volume, about 25% more grinding media surface area is available for size reduction when charged with Cylpebs, but the mill would also draw more power.
industrial ball mills: steel ball mills and lined ball mills | orbis
Particle size reduction of materials in a ball mill with the presence of metallic balls or other media dates back to the late 1800s. The basic construction of a ball mill is a cylindrical container with journals at its axis. The cylinder is filled with grinding media (ceramic or metallic balls or rods), the product to be ground is added and the cylinder is put into rotation via an external drive causing the media to roll, slide and cascade. Lifting baffles are supplied to prevent the outer layer of media to simply roll around the cylinder.
Mill cylinders are typically supplied with a cooling jacket on their cylindrical portion for temperature control, especially when processing temperature-sensitive materials. For extreme temperatures, the ends of the cylinder can also be furnished with cooling apparatus.
ball mill&rod mill grinding system used in mineral milling | prominer (shanghai) mining technology co.,ltd
Grinding system is the section consuming power most in mineral processing plant. It accounts for up to 40% of the total power consumption in mineral processing plant operations. So, selecting the efficient solution for grinding section is very important.
Prominer provides ball mill / rod mill grinding system which is widely used in various types of ores' beneficiation, electricity, cement and chemical industries. It can carry out dry or wet pulverizing and can meet demand for sustainable large-scale production. Our ball mill / rod mill grinding solution for different minerals with the features as below:
Lower power consumption & operation cost
Air clutch system for starting the motor safely
Alternative synchronous or asynchronous motor
Low speed driving unit with lifting device, convenient for maintenance.
New endurable wearing parts to increase service life of vulnerable parts.
Skid-mounted design with fast delivery and short erection time
Prominer has been devoted to mineral processing industry for decades and specializes in mineral upgrading and deep processing. With expertise in the fields of mineral project development, mining, test study, engineering, technological processing.