veracruz efficient large stone ball mill manufacturer

vertical roller mill,raymond mill,roller mill,raymond roller mill,raymond mill manufacturer_shuguang heavy machinery

vertical roller mill,raymond mill,roller mill,raymond roller mill,raymond mill manufacturer_shuguang heavy machinery

Before selecting and machinery cooperation, everywhere I looked at a lot of manufacturers, are not satisfied! Finally hold a glimmer of hope to visit Pu run factories, but it can make me satisfied, or ...

I and the Shuguang machine were old friends, is a friend introduced to me, Shuguang Machinery attaches great importance to integrity, service attitude is very good, all products are factory production,...

Zhengzhou Shuguang Heavy Machinery Co.,Ltd Zhengzhou Shuguang Heavy Machinery Co., Ltd. was foundedin 1993, the company headquarters is located in the beautiful city of Zhengzhou shangjiemechanical processing zone, is a companydedicated to all kinds of milling machine, Raymond machine, also known as Raymond Mill or Raymond Grinding machine(including stone mill, calcite milling machine, talc powder mill, limestone mill, calcite Raymond Mill, limestone Raymond Mill and other pr......

grinding equipment, calcination equipments products from china manufacturers - citichl heavy industries co., ltd. - page 1

grinding equipment, calcination equipments products from china manufacturers - citichl heavy industries co., ltd. - page 1

Ball Mill, Jaw Crusher, Mine Hoist manufacturer / supplier in China, offering Rotary Kiln Spare Parts Rotary Kiln Tyre/Ring, Factory Sell Vertical Shaft Impact Crusher for Sand Stone Making/Limestone Crusher, Mining Parts Stainless Forging&Casting Pinion Shaft/Shaft Manufacturer and so on.

jaw stone crusher, mobile stone crusher, stone crushing line-zhengzhou unique group co., ltd

jaw stone crusher, mobile stone crusher, stone crushing line-zhengzhou unique group co., ltd

Because a lot of development of mineral resources, the amount of resources available to continue to decline, resulting in taste dwindling ore mining, smelting and other follow-up processing for beneficiation product quality requirements are increasing. 2015-08-18

Biaxial garbage crusher by shearing, extrusion material to achieve reduced size so as to achieve the purpose of crushing. Zhengzhou UNIQUE Equipment Co., Ltd. introduced advanced production experience, improve research and development, the introduction of the technology is mature 2015-08-18

Dry-type ball mill, also known as dry mill. Used in metallurgy, chemical, power and other grinding various ores and other materials may be grinding. It is widely used in cement, silicate products, new building materials, refractory materials, fertilizer, ferrous and nonferrous metal and glass ceramics and other production industries. 2015-08-13

Jaw crusher in mining, building materials, infrastructure and other sectors is mainly used for crushing machine and the broken machine. Jaw crusher can be divided into large, medium and small three. According to the movable jaw swing in different ways, it can be divided into simple swing jaw crusher, 2015-08-12

Cone crusher mobile crushing plant is developed by our company introduced a new rock crushing equipment, greatly expanding the crushing, crushing operations domain concepts. It is designed to provide customers with simple, efficient, low-cost operation of the project hardware. 2015-08-12

hengzhou UNIQUE made small crusher can be used for crushing, glass, steel, rubber, paper, old carpet, wood pallets, garbage, scrap metal, large diameter metal trunk and other environmentally friendly recycling broken. In addition to our standard model series, based on the special needs of users 2015-08-10

Impact crusher, is the introduction of foreign advanced crusher principle and technology, combined with the actual situation of sand production, research and development of high efficiency crushing equipment leading level. It is widely used in a variety of rock, iron ore, concrete aggregate and other hard, brittle materials in the debris, fine. 2015-08-10

Jaw crusher jaw broken short, the most popular in the crushing production line is often used as a primary crusher and secondary crusher, all materials used to breaking strength in 320Mpa less, such as basalt, granite, marble, limestone , bluestone, coal and gypsum. 2015-08-07

Flotation machine driven by a motor V-belt drive impeller rotation, a centrifugal vacuum formed, on the one hand inhalation of sufficient air is mixed with the slurry, while stirring the pulp is mixed with the drug, while refined foam, foam on top fossil bond, float to the surface and then form slurry bubble mineralization. 2015-08-07

grinding mill design & ball mill manufacturer

grinding mill design & ball mill manufacturer

All Grinding Mill & Ball Mill Manufacturers understand the object of the grinding process is a mechanical reduction in size of crushable material. Grinding can be undertaken in many ways. The most common way for high capacity industrial purposes is to use a tumbling charge of grinding media in a rotating cylinder or drum. The fragmentation of the material in that charge occurs through pressure, impact, and abrasion.

The choice of mill design depends on the particle size distribution in the feed and in the product wanted. Often the grinding is more economic when executed in a primary step, followed by a secondary step, giving a fine size product.

C=central trunnion discharge P=peripheral discharge R=spherical roller trunnion bearing, feed end H=hydrostatic shoe bearing, feed end R=spherical roller trunnion bearing, discharge end K=ring gear and pinion drive

Type CHRK is designed for primary autogenous grinding, where the large feed opening requires a hydrostatic trunnion shoe bearing. Small and batch grinding mills, with a diameter of 700 mm and more, are available. These mills are of a special design and described on special request by allBall Mill Manufacturers.

The different types of grinding mills are based on the different types of tumbling media that can be used: steel rods (rod mills), steel balls (ball mills), and rock material (autogenous mills, pebble mills).

The grinding charge in a rod mill consists of straight steel rods with an initial diameter of 50-100 mm. The length of the rods is equal to the shell length inside the head linings minus about 150 mm. The rods are fed through the discharge trunnion opening. On bigger mills, which need heavy rods, the rod charging is made with a pneumatic or manual operated rod charging device. The mill must be stopped every day or every second day for a few minutes in order to add new rods and at the same time pick out broken rod pieces.

As the heavy rod charge transmits a considerable force to each rod, a rod mill can not be built too big. A shell length above 6100 mm can not be recommended. As the length to diameter ratio of the mill should be in the range of 1,2-1,5, the biggest rod mill will convert maximum 1500 kW.

Rod mills are used for primary grinding of materials with a top size of 20-30 mm (somewhat higher for soft materials). The production of fines is low and consequently a rod mill is the right machine when a steep particle size distribution curve is desired. A product with 80% minus 500 microns can be obtained in an economical manner.

The grinding charge in a ball mill consist of cast or forged steel balls. These balls are fed together with the feed and consequently ball mills can be in operation for months without stopping. The ball size is often in the diameter range of 20-75 mm.

The biggest size is chosen when the mill is used as a primary grinding mill. For fine grinding of e.g. sands, balls can be replaced by cylpebs, which are heat treated steel cylinders with a diameter of 12-40 mm and with the same length as the diameter.

Ball mills are often used as secondary grinding mills and for regrinding of middlings in concentrators. Ball mills can be of the overflow or of the grate discharge type. Overflow discharge mills are used when a product with high specific surface is wanted, without any respect to the particle size distribution curve. Overflow discharge mills give a final product in an open circuit. Grate discharge mills are used when the grinding energy shall be concentrated to the coarse particles without production of slimes. In order to get a steep particle size distribution curve, the mill is used in closed circuit with some kind of classifier and the coarse particles known as classifier underflow are recycled. Furthermore, it should be observed that a grate discharge ball mill converts about 20% more energy than an overflow discharge mill with the same shell dimensions.

Ball mill shells are often furnished with two manholes. Ball mills with small balls or cylpebs can produce the finest product of all tumbling mills. 80% minus 74 microns is a normal requirement from the concentrators.The CRRK series of wet grinding ball mills are tabulatedbelow.

No steel grinding media is used in a fully autogenous mill. When choosing primary autogenous grinding, run of mine ore up to 200-300 mm in size is fed to the mill. When using a crushing step before the grinding, the crusher setting should be 150-200 mm. The feed trunnion opening must be large enough to avoid plugging. The biggest pieces in the mill are important for the size reduction of middle size pieces, which in their turn are important for the finer grinding. Thus the tendency of the material to be reduced in size by pressure, impact, and abrasion is a very important question when primary autogenous grinding is proposed.

When autogenous grinding is used in the second grinding step, the grinding media is size-controlled and often in the range of 30-70 mm. This size is called pebbles and screened out in the crushing station and fed to the mill in controlled proportion to the mill power. The pebble weight is 5-25% of the total feed to the plant, depending on the strength of the pebbles. Sometimes waste rock of high strength is used as pebbles.

Pebble mills should always be of the grate discharge type. The energy that can be converted in a mill depends on the total weight of the grinding charge. Consequently, pebble mills convert less power per mill volume unit than rod and ball mills.

High quality steel rods and balls are a considerable part of the operating costs. Autogenous grinding should, therefore, be considered and tested when a new plant shall be designed. As a grinding mill is built to last for decades, it is more important to watch the operation costs than the price of the mill installation. The CRRK series of wet grinding pebble mills are tabulated below.

Wet grinding is definitely the most usual method of grinding minerals as it incorporates many advantages compared to dry grinding. A requirement is, however, that water is available and that waste water, that can not be recirculated, can be removed from the plant without any environmental problems. Generally, the choice depends on whether the following processing is wet or dry.

When grinding to a certain specific surface area, wet grinding has a lower power demand than dry grinding. On the other hand, the wear of mill lining and grinding media is lower in dry grinding. Thus dry grinding can be less costly.

The feed to a dry grinding system must be dried if the moisture content is high. A ball mill is more sensitive to clogging than a rod mill. An air stream through the mill can reduce the moisture content and thus make a dry grinding possible in certain applications.

Due to the hindering effect that the ball charge gives to the material flow in dry grinding, the ball charge is not more than 28-35% of the mill volume. This should be compared with 40-45% in wet grinding. The expression used for this phenomenon is that the charge in a dry grinding mill is swollen.

Big dry grinding ball mills are often two-compartment mills, with big balls in the first compartment and small balls or cylpebs in the second one. An extra grate wall is used to separate the two charges.

The efficiency of wet grinding is affected by the percentage of solids. If the pulp is too thick, the grinding media becomes covered by too thick a layer of material, which hinders grinding. The opposite effect may be obtained if the dilution is too high, and this may also reduce the grinding efficiency. A high degree of dilution may sometimes be desirable in order to suppress excessive slime formation.

The specific power required for a certain grinding operation, usually expressed in kWh/ton, is a function of both the increase in the specific surface of the material (expressed in cm/cm or cm/g) and of the grinding resistance of the material. This can be expressed by the formula

where c is a material constant representing the grinding resistance, and So and S are the specific surfaces of the material before and after the grinding operation respectively. The formula is an expression of Rittingers Law which is shown by tests to be reasonably accurate up to a specific surface of 10,000 cm/cm.

When the grinding resistance c has been determined by trial grinding to laboratory scale, the net power E required for each grinding stage desired may be determined by the formula, at least as long as Rittingers Law is valid. If grinding is to be carried out not to a certain specific surface S but to a certain particle size k, the correlation between S and k must be determined. The particle size is often expressed in terms of particle size at e.g. 95, 90 or 80% quantity passing and is denoted k95, k90 or k80.

where E =the specific power consumption expressed in kWh/short ton. Eo = a proportionality and work factor called work index k80p = particle size of the product at 80% passage (micron) k80f =the corresponding value for the raw material (micron)

The value of Eo is a function of the physical properties of the raw material, the screen analyses of the product and raw material respectively, and the size of the mill. The value for easily-ground materials is around 7, while for materials that have a high grinding resistance the value is around 17.

Eo is correlated to a certain reduction ratio, mill diameter etc. Corrections must be made for each case. The simplest method of calculating the specific power consumption is test grinding in a laboratory mill, and comparison of the results with a known reference material. The sample is ground in batches for 3, 6,12 minutes, a screen analysis is carried out after each period, after which the specific surface is determined. A good estimate of the grinding characteristics of the sample can be obtained by comparison of the specific surfaces with corresponding values for the reference material.

When the net power required has been determined, an allowance is made for mechanical losses. The gross power requirement thus arrived at, should with a satisfactory margin be utilised by the mill selected.

The critical speed of a rotating mill is the RPM at which a grinding medium will begin to centrifuge, namely will start rotating with the mill and therefore cease to carry out useful work. This will occur at an RPM of ncr, which may be determined by the formula

where D is the inside diameter in meters of the mill. Mills are driven in practice at a speed corresponding to 60-80% of the critical speed, the choice of speed being influenced by economical considerations. Within that range the power is nearly proportional to the speed.

The charge volume in the case of rod and ball mills is a measure of the proportion of the mill body that is filled by rods or balls. When the mill is stationary, raw material and liquid should fill the voids between the grinding media, in order that these should be fully utilized.

Maximum mill efficiency is reached at a charge volume of approximately 55%, but for a number of reasons 45-50% is seldom exceeded. The efficiency curve is in any case quite flat about the maximum. In overflow mills the charge volume is usually 40%, while there is a greater choice in the case of grate discharge mills.

For coarse grinding in rod mills, the rods used have a diameter of 50-100 mm and their lengths are approx. 150 mm below the effective inside shell length. Rods will break when they have been worn down to about 20 mm and broken rods must from time to time be taken out of the mill since otherwise they will reduce the mill capacity and may cause blockage through piling up. The first rod charge should also contain a number of rods of smaller diameter.

It may be necessary to charge the mill with rods of smaller diameter when fine grinding is to be carried out in a rod mill. Experience shows that the size of the grinding media should bear a definite relationship to the size of both the raw material and the finished product in order that optimum grinding may be achieved. The largest grinding media must be able to crush and grind the largest pieces of rock, while on the other hand the grinding media should be as small as possible since the total active surface increases in inverse proportion to the diameter.

A crushed mineral whose largest particles pass a screen with 25 x 25 mm apertures shall be ground to approx. 95% passing 0.1 mm in a 2.9 x 3.2 m ball mill of 35 ton charge weight. In accordance with Olewskis formula

Grinding media wear away because of the attrition they are subjected to in the course of the grinding operation, and in addition a continuous reduction in weight takes place owing to corrosion. The rate of wear will in the first place depend on the abrasive properties of the mineral being ground and naturally also on the hardness of the grinding media themselves.

The wear of rods and balls is usually quoted in grammes per ton of material processed (dry weight) and normal values may lie between 100 and 1500 g/ton. Considerably higher wear figures may however be experienced in fine wet grinding of e.g. very hard siliceous sand.

A somewhat more accurate way of expressing wear is to state the amount of gross kWh of grinding power required to consume 1 kg of grinding media. A normal value in wet grinding is 15 kWh/kg.The wear figures in dry grinding are only 10-30 % of the above.

where c is a constant which, inter alia, takes into consideration the mean slope a of the charge, W is the weight in kp of the charge n is the RPM Rg is the distance in metres of the centre of gravity from the mill centre

W for rod and ball mills shall be taken as the weight of the rod or ball charge, i.e. the weight of the pulp is to be ignored. For pebble mills therefore W is to be calculated on the basis of the bulk weight of the pebbles.

It should be pointed out that factor c in the formula is a function of both the shape of the inner lining (lifter height etc.) and the RPM. The formula is however valid with sufficient accuracy for normal speeds and types of lining.

The diagram gives the values of the quantity Rg/d as a function of the charge volume, the assumption being that the charge has a plane surface and is homogeneous, d is the inside diameter of the mill in metres. The variation of the quantity a/d, where a is the distance between the surface of the charge and the mill centre, is also shown in the same figure.

In order to keep manufacturing costs at a minimum level, Morgardshammar has a series of standard mill diameters up to and including 6.5 m. Shell length, however, can be varied and tailor made for each application. The sizes selected are shown on the tables on page 12-13 and cover the power range of 200-5000 kW.

Shells with a diameter of up to about 4 m are made in one piece. Above this dimension, the shell is divided into a number of identical pieces, bolted together at site, in order to facilitate the transport. The shell is rolled and welded from steel plate and is fitted with welded flanges of the same material. The flanges are machined in order to provide them with locating surfaces fitting into the respective heads. The shells of ball and pebble mills are provided with 2 manholes with closely fitting covers. The shells have drilled holes for different types of linings.

Heads with a diameter of up to about 4 m are integral cast with the trunnion in one piece. Above this diameter the trunnion is made as a separate part bolted to the head. The head can then be divided in 2 or 4 pieces for easy transport and the pieces are bolted together at site. The material is cast steel or nodular iron. The heads and the trunnions have drilled holes for the lining.

Spherical roller (antifriction) bearings are normally used. They offer the most modern and reliable technology and have been used for many years. They are delivered with housings in a new design with ample labyrinth seals.

For very large trunnions or heavy mills, i.e. for primary autogenous grinding mills. Morgardshammar uses hydrostatic shoe bearings. They have many of the same advantages as roller bearings. They work with circulating oil under pressure.

The spherical roller bearing and the hydrostatic shoe bearing take a very limited axial space compared to a conventional sleeve bearing. This means that the lever of the bearing load is short. Furthermore, the bending moment on the head is small and as a result of this, the stress and deformation of the head are reduced. Ask Morgardshammar for special literature on trunnion bearings.

Ring gears are often supplied with spur gears. They are always split in 2 or 4 pieces in order to facilitate the assembly. Furthermore, they are symmetrical and can be turned round in order to make use of both tooth flanks. The material is cast steel or nodular iron. They are designed in accordance with AGMA.The ring gear may be mounted on either the feed or the discharge head. It is fitted with a welded plate guard.

The pinion and the counter shaft are integral forged and heat treated of high quality steel. For mill power exceeding about 2500 kW two pinions are used, one on each side of the mill (double-drive). The pinion is supported on two spherical roller bearings.

The trunnion bearings are lubricated by means of a small motor- driven grease lubricator. The gear ring is lubricated through a spray lubricating system, connected to the electric and pneumatic lines. The spray nozzles are mounted on a panel on the gear ring guard.

In order to protect the parts of the mill that come into contact with the material being ground, a replaceable lining of wear-resistant material is fitted. This may take the form of unalloyed or alloyed rolled or cast steel, heat treated if required, or rubber of the appropriate wear resistant quality. White cast iron, unalloyed or alloyed with nickel (Ni-hard), may also be used.

The shape of the mill lining is often of Lorain-type, consisting of plates held in place between lifter bars (or key bars) of suitable height bolted on to the shell. This system is used i.e. of all well-known manufacturers of rubber linings. Ball mills and autogenous mills with metal lining also can be provided with single or double waved plates without lifter bars.

In grate discharge mills the grate and the discharge lifters are a part of the lining. The grate plates with tapered slots or holes are of metal or rubber design. The discharge lifters are fabricated steel with thick rubber coating. Rubber layer for metal linings and heavy corner pieces of rubber are included in a Morgardshammar delivery as well as attaching bolts, washers, seal rings, and self-locking nuts. A Morgardshammar overflow mill can be converted into a grate discharge mill only by changing some liner parts and without any change of the mill. Trunnion liners are rubber coated fabricated steel or cast steel. In grate discharge mills the center cone and the trunnion liner form one piece.

Scoop feeders in combination with drum feeders are used when retaining oversize from a spiral or rake classifier. As hydrocyclones are used in most closed grinding circuits the spout feeders are used most frequently.

Vibrating feeders or screw feeders are used when charging feed to dry grinding mills. Trommel screens are used to protect slurry pumps and other transport equipment from tramp iron. Screens can have perforated rubber sheets or wire mesh. The trommel screens are bolted to the discharge trunnion lining.

Inching units for slow rotation of the mills are also furnished. Rods to the rod mills are charged by means of manual or automatic rod charges. Erection cradles on hydraulic jacks are used when erecting medium or big size mills at site.

A symbol of dependable quality ore milling machinery manufacturing, industrial and mining equipment, ball mills and rod mills as well as supplies created for your specific needs. During this period thousands of operators have experienced continuous economical and unequalled service through their use.As anindustrial ball mill manufacturer and supplier, we havecontinuously accumulated knowledge on grinding applications. It has contributed greatly to the grinding process through the development and improvement of such equipment.

Just what is grinding? It is the reduction of lump solid materials to smaller particles by the application of shearing forces, pressure, attrition, impact and abrasion. The primary consideration, then, has been to develop some mechanical means for applying these forces. The modern grinding mill applies power to rotate the mill shell and thus transmits energy to some form of media which, in turn, fractures individual particles.

Through constant and extensive research, in the field of grinding as well as in the field of manufacturing. Constantly changing conditions provide a challenge for the future. Meeting this challenge keeps our company young and progressive. This progressive spirit, with the knowledge gained through the years, assures top quality equipment for the users of our mills.

You are urged to study the following pages which present a detailed picture of our facilities and discuss the technical aspects of grinding. You will find this data helpful when considering the selection of the grinding equipment.

It is quite understandable that wetakes pride in the quality of our mills.Complementing the human craftsmanship built into these mills, our plants are equipped with modern machines of advanced design which permit accurate manufacturing of each constituent part. Competent supervision encourages close inspection of each mill both as to quality and proper fabrication. Each mill produced is assured of meeting the high required standards. New and higher speed machines have replaced former pieces of equipment to provide up-to-date procedures. The use of high speed cutting and drilling tools has stepped up production, thereby reducing costs and permitting us to add other refinements and pass these savings on to you, the consumer.

Each foundry heat is checked metallurgically prior to pouring. All first castings of any new design are carefully examined by the use of an X-ray machine to be certain of uniformity of structure. The X -ray is also used to check welding work, mill heads, and other castings.

Each Mills, regardless of size, is designed to meet the specific grinding conditions under which it will be used. The speed of the mill type of liner, discharge arrangement, size of feeder, size of bearings, mill diameter and length, and other factors are all considered to take care of the size of feed, tonnage, circulating sand load, selection of balls or rods, and the final size of grind.

All Mills are built with jigs and templates so that any part may be duplicated. A full set of detailed drawings is made for each mill and its parts. This record is kept up to date during the life of the mill. This assures accurate duplication for the replacement of wearing parts during the future years.

As a part of our service our staff includes experienced engineers, trained in the field of metallurgy with special emphasis on grinding work. This knowledge, as well as a background gained from intimate contact with various operating companies throughout the world, provides a sound basis for consultation on your grinding problems. We take pride in manufacturing rod mills and ball millsfor the metallurgical, rock products, cement, process, and chemical industries.

As an additional service we offer our testing laboratories to check your material for grindability. Since all grinding problems are different some basis must be established for recommending the size and type of grinding equipment required. Experience plays a great part in this phase however, to establish more direct relationships it is often essential to conduct individual grindability tests on the specific material involved. To do this we have established certain definite procedures of laboratory grinding work to correlate data obtained on any new specific material for comparison against certain standards. Such standards have been established from conducting similar work on material which is actually being ground in Mills throughout the world. The correlation between the results we obtain in our laboratory against these standards, coupled with the broad experience and our companys background, insures the proper selection and recommendation of the required grinding equipment.

When selecting a grinding mill there are many factors to be taken into consideration. First let us consider just what constitutes a grinding mill. Essentially it is a revolving, cylindrical shaded machine, the internal volume of which is approximately one-half filled with some form of grinding media such as steel balls, rods or non-ferrous pebbles.

Feed may be classified as hard, average or soft. It may be tough, brittle, spongy, or ductile. It may have a high specific gravity or a low specific gravity. The desired product from a mill may range in size from a 4 mesh down to 200 mesh, or into the fine micron sizes. For each of these properties a different mill would be indicated.

The Mill has been designed to carry out specific grinding work requirements with emphasis on economic factors. Consideration has been given to minimizing shut-down time and to provide long, dependable trouble-free operation. Wherever wear takes place renewable parts have been designed to provide maximum life. A Mill, given proper care, will last indefinitely.

Mills have been manufactured in a wide variety of sizes ranging from laboratory units to mills 12 in diameter, with any suitable length. Each of these mills, based on the principles of grinding, provides the most economical grinding apparatus.

For a number of years ball mill grinding was the only step in size reduction between crushing and subsequent treatment. Subsequently smaller rod mills have altered this situation, providing in some instances a more economical means of size reduction in the coarser fractions. The principal field of rod mill usage is the preparation of products in the 4-mesh to 35-mesh range. Under some conditions it may be recommended for grinding to about 48 mesh. Within these limits a rod mill is often superior to and more efficient than a ball mill. It is frequently used for such size reduction followed by ball milling to produce a finished fine grind. It makes a product uniform in size with only a minimum amount of tramp oversize.

The basic principle by which grinding is done is reduction by line contact between rods extending the full length of the mill. Such line contact results in selective grinding carried out on the largest particle sizes. As a result of this selective grinding work the inherent tendency is to make size reduction with the minimum production of extreme fines or slimes.

The small rod mill has been found advantageous for use as a fine crusher on damp or sticky materials. Under wet grinding conditions this feed characteristic has no drawback for rod milling whereas under crushing conditions those characteristics do cause difficulty. This asset is of particular importance in the manufacture of sand, brick, or lime where such material is ground and mixed with just sufficient water to dampen, but not to produce a pulp. The rod mill has been extensively used for the reduction of coke breeze in the 8-mesh to 20-mesh size range containing about 10% moisture to be used for sintering ores.

Grinding by use of nearly spherical shaped grinding media is termed ball milling. Strictly speaking, such media are made of steel or iron. When iron contamination is detrimental, porcelain or natural non-metallic materials are used and are referred to as pebbles. When ore particles are used as grinding media this is known as autogenous grinding.

Other shapes of media such as short cylinders, cubes, cones, or irregular shapes have been used for grinding work but today the nearly true spherical shape is predominant and has been found to provide the most economic form.

In contrast to rod milling the grinding action results from point contact rather than line contact. Such point contacts take place between the balls and the shell liners, and between the individual balls themselves. The material at those points of contact is ground to extremely fine sizes. The present day practice in ball milling is generally to reduce material to 35 mesh or finer. Grinding in a ball mill is not selective as it is in a rod mill and as a result more extreme fines and tramp oversize are produced.

Small Ball mills are generally recommended not only for single stage fine grinding but also have wide application in regrind work. The Small Ball millwith its low pulp level is especially adapted to single stage grinding as evidenced by hundreds of installations throughout the world. There are many applications in specialized industrial work for either continuous or batch grinding.

Wet grinding may be considered as the grinding of material in the presence of water or other liquids in sufficient quantity to produce a fluid pulp (generally 60% to 80% solids). Dry grinding on the other hand is carried out where moisture is restricted to a very limited amount (generally less than 5%). Most materials may be ground by use of either method in either ball mills or rod mills. Selection is determined by the condition of feed to the mill and the requirements of the ground product for subsequent treatment. When grinding dry some provision must be made to permit material to flow through the mill. Mills provide this necessary gradient from the point of feeding to point of discharge and thereby expedites flow.

The fineness to which material must be ground is determined by the individual material and the subsequent treatment of that ground material Where actual physical separation of constituent particles is to be realized grinding must be carried to the fineness where the individual components are separated. Some materials are liberated in coarse sizes whereas others are not liberated until extremely fine sizes are reached.

Occasionally a sufficient amount of valuable particles are liberated in coarser sizes to justify separate treatment at that grind. This treatment is usually followed by regrinding for further liberation. Where chemical treatment is involved, the reaction between a solid and a liquid, or a solid and a gas, will generally proceed more rapidly as the particle sizes are reduced. The point of most rapid and economical change would determine the fineness of grind required.

Laboratory examinations and grinding tests on specific materials should be conducted to determine not only the fineness of grind required, but also to indicate the size of commercial equipment to handle any specific problem.

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Water Well Drilling Rig, DTH Drilling Rig, Rotary Drilling Rig manufacturer / supplier in China, offering Hfx500 400mm Diesel Crawler Type Borehole Drill Water Well Drilling Rig, Hfx500 500m Crawler Type Pneumatic Water Well Drilling Rig for Sale, Hfx500 Crawler Type Hydraulic Water Well Drilling Rig Borehole Drilling Machine and so on.

Hanfa Group established in 1998 is a key enterprise in the industry of geological exploration and water well field, with the ability to research, manufacture and market. Presently, it has three subsidiaries which are Zhengzhou Hanfa Prospecting Machinery Co., Ltd, Zhengzhou Hanfa Imp & Exp Trading Co., Ltd, HK Hanfa Imp & Exp Trading Co., Ltd. It has experienced engineers, professional R&D team, special after service team, world class sophisticated equipment and advanced technology guarantee the best ...

ball mills

ball mills

In all ore dressing and milling Operations, including flotation, cyanidation, gravity concentration, and amalgamation, the Working Principle is to crush and grind, often with rob mill & ball mills, the ore in order to liberate the minerals. In the chemical and process industries, grinding is an important step in preparing raw materials for subsequent treatment.In present day practice, ore is reduced to a size many times finer than can be obtained with crushers. Over a period of many years various fine grinding machines have been developed and used, but the ball mill has become standard due to its simplicity and low operating cost.

A ball millefficiently operated performs a wide variety of services. In small milling plants, where simplicity is most essential, it is not economical to use more than single stage crushing, because the Steel-Head Ball or Rod Mill will take up to 2 feed and grind it to the desired fineness. In larger plants where several stages of coarse and fine crushing are used, it is customary to crush from 1/2 to as fine as 8 mesh.

Many grinding circuits necessitate regrinding of concentrates or middling products to extremely fine sizes to liberate the closely associated minerals from each other. In these cases, the feed to the ball mill may be from 10 to 100 mesh or even finer.

Where the finished product does not have to be uniform, a ball mill may be operated in open circuit, but where the finished product must be uniform it is essential that the grinding mill be used in closed circuit with a screen, if a coarse product is desired, and with a classifier if a fine product is required. In most cases it is desirable to operate the grinding mill in closed circuit with a screen or classifier as higher efficiency and capacity are obtained. Often a mill using steel rods as the grinding medium is recommended, where the product must have the minimum amount of fines (rods give a more nearly uniform product).

Often a problem requires some study to determine the economic fineness to which a product can or should be ground. In this case the 911Equipment Company offers its complete testing service so that accurate grinding mill size may be determined.

Until recently many operators have believed that one particular type of grinding mill had greater efficiency and resulting capacity than some other type. However, it is now commonly agreed and accepted that the work done by any ballmill depends directly upon the power input; the maximum power input into any ball or rod mill depends upon weight of grinding charge, mill speed, and liner design.

The apparent difference in capacities between grinding mills (listed as being the same size) is due to the fact that there is no uniform method of designating the size of a mill, for example: a 5 x 5 Ball Mill has a working diameter of 5 inside the liners and has 20 per cent more capacity than all other ball mills designated as 5 x 5 where the shell is 5 inside diameter and the working diameter is only 48 with the liners in place.

Ball-Rod Mills, based on 4 liners and capacity varying as 2.6 power of mill diameter, on the 5 size give 20 per cent increased capacity; on the 4 size, 25 per cent; and on the 3 size, 28 per cent. This fact should be carefully kept in mind when determining the capacity of a Steel- Head Ball-Rod Mill, as this unit can carry a greater ball or rod charge and has potentially higher capacity in a given size when the full ball or rod charge is carried.

A mill shorter in length may be used if the grinding problem indicates a definite power input. This allows the alternative of greater capacity at a later date or a considerable saving in first cost with a shorter mill, if reserve capacity is not desired. The capacities of Ball-Rod Mills are considerably higher than many other types because the diameters are measured inside the liners.

The correct grinding mill depends so much upon the particular ore being treated and the product desired, that a mill must have maximum flexibility in length, type of grinding medium, type of discharge, and speed.With the Ball-Rod Mill it is possible to build this unit in exact accordance with your requirements, as illustrated.

To best serve your needs, the Trunnion can be furnished with small (standard), medium, or large diameter opening for each type of discharge. The sketch shows diagrammatic arrangements of the four different types of discharge for each size of trunnion opening, and peripheral discharge is described later.

Ball-Rod Mills of the grate discharge type are made by adding the improved type of grates to a standard Ball-Rod Mill. These grates are bolted to the discharge head in much the same manner as the standard headliners.

The grates are of alloy steel and are cast integral with the lifter bars which are essential to the efficient operation of this type of ball or rod mill. These lifter bars have a similar action to a pump:i. e., in lifting the product so as to discharge quickly through the mill trunnion.

These Discharge Grates also incorporate as an integral part, a liner between the lifters and steel head of the ball mill to prevent wear of the mill head. By combining these parts into a single casting, repairs and maintenance are greatly simplified. The center of the grate discharge end of this mill is open to permit adding of balls or for adding water to the mill through the discharge end.

Instead of being constructed of bars cast into a frame, Grates are cast entire and have cored holes which widen toward the outside of the mill similar to the taper in grizzly bars. The grate type discharge is illustrated.

The peripheral discharge type of Ball-Rod Mill is a modification of the grate type, and is recommended where a free gravity discharge is desired. It is particularly applicable when production of too many fine particles is detrimental and a quick pass through the mill is desired, and for dry grinding.

The drawings show the arrangement of the peripheral discharge. The discharge consists of openings in the shell into which bushings with holes of the desired size are inserted. On the outside of the mill, flanges are used to attach a stationary discharge hopper to prevent pulp splash or too much dust.

The mill may be operated either as a peripheral discharge or a combination or peripheral and trunnion discharge unit, depending on the desired operating conditions. If at any time the peripheral discharge is undesirable, plugs inserted into the bushings will convert the mill to a trunnion discharge type mill.

Unless otherwise specified, a hard iron liner is furnished. This liner is made of the best grade white iron and is most serviceable for the smaller size mills where large balls are not used. Hard iron liners have a much lower first cost.

Electric steel, although more expensive than hard iron, has advantage of minimum breakage and allows final wear to thinner section. Steel liners are recommended when the mills are for export or where the source of liner replacement is at a considerable distance.

Molychrome steel has longer wearing qualities and greater strength than hard iron. Breakage is not so apt to occur during shipment, and any size ball can be charged into a mill equipped with molychrome liners.

Manganese liners for Ball-Rod Mills are the world famous AMSCO Brand, and are the best obtainable. The first cost is the highest, but in most cases the cost per ton of ore ground is the lowest. These liners contain 12 to 14% manganese.

The feed and discharge trunnions are provided with cast iron or white iron throat liners. As these parts are not subjected to impact and must only withstand abrasion, alloys are not commonly used but can be supplied.

Gears for Ball-Rod Mills drives are furnished as standard on the discharge end of the mill where they are out of the way of the classifier return, scoop feeder, or original feed. Due to convertible type construction the mills can be furnished with gears on the feed end. Gear drives are available in two alternative combinations, which are:

All pinions are properly bored, key-seated, and pressed onto the steel countershaft, which is oversize and properly keyseated for the pinion and drive pulleys or sheaves. The countershaft operates on high grade, heavy duty, nickel babbitt bearings.

Any type of drive can be furnished for Ball-Rod Mills in accordance with your requirements. Belt drives are available with pulleys either plain or equipped with friction clutch. Various V- Rope combinations can also be supplied.

The most economical drive to use up to 50 H. P., is a high starting torque motor connected to the pinion shaft by means of a flat or V-Rope drive. For larger size motors the wound rotor (slip ring) is recommended due to its low current requirement in starting up the ball mill.

Should you be operating your own power plant or have D. C. current, please specify so that there will be no confusion as to motor characteristics. If switches are to be supplied, exact voltage to be used should be given.

Even though many ores require fine grinding for maximum recovery, most ores liberate a large percentage of the minerals during the first pass through the grinding unit. Thus, if the free minerals can be immediately removed from the ball mill classifier circuit, there is little chance for overgrinding.

This is actually what has happened wherever Mineral Jigs or Unit Flotation Cells have been installed in the ball mill classifier circuit. With the installation of one or both of these machines between the ball mill and classifier, as high as 70 per cent of the free gold and sulphide minerals can be immediately removed, thus reducing grinding costs and improving over-all recovery. The advantage of this method lies in the fact that heavy and usually valuable minerals, which otherwise would be ground finer because of their faster settling in the classifier and consequent return to the grinding mill, are removed from the circuit as soon as freed. This applies particularly to gold and lead ores.

Ball-Rod Mills have heavy rolled steel plate shells which are arc welded inside and outside to the steel heads or to rolled steel flanges, depending upon the type of mill. The double welding not only gives increased structural strength, but eliminates any possibility of leakage.

Where a single or double flanged shell is used, the faces are accurately machined and drilled to template to insure perfect fit and alignment with the holes in the head. These flanges are machined with male and female joints which take the shearing stresses off the bolts.

The Ball-Rod Mill Heads are oversize in section, heavily ribbed and are cast from electric furnace steel which has a strength of approximately four times that of cast iron. The head and trunnion bearings are designed to support a mill with length double its diameter. This extra strength, besides eliminating the possibility of head breakage or other structural failure (either while in transit or while in service), imparts to Ball-Rod Mills a flexibility heretofore lacking in grinding mills. Also, for instance, if you have a 5 x 5 mill, you can add another 5 shell length and thus get double the original capacity; or any length required up to a maximum of 12 total length.

On Type A mills the steel heads are double welded to the rolled steel shell. On type B and other flanged type mills the heads are machined with male and female joints to match the shell flanges, thus taking the shearing stresses from the heavy machine bolts which connect the shell flanges to the heads.

The manhole cover is protected from wear by heavy liners. An extended lip is provided for loosening the door with a crow-bar, and lifting handles are also provided. The manhole door is furnished with suitable gaskets to prevent leakage.

The mill trunnions are carried on heavy babbitt bearings which provide ample surface to insure low bearing pressure. If at any time the normal length is doubled to obtain increased capacity, these large trunnion bearings will easily support the additional load. Trunnion bearings are of the rigid type, as the perfect alignment of the trunnion surface on Ball-Rod Mills eliminates any need for the more expensive self-aligning type of bearing.

The cap on the upper half of the trunnion bearing is provided with a shroud which extends over the drip flange of the trunnion and effectively prevents the entrance of dirt or grit. The bearing has a large space for wool waste and lubricant and this is easily accessible through a large opening which is covered to prevent dirt from getting into the bearing.Ball and socket bearings can be furnished.

Scoop Feeders for Ball-Rod Mills are made in various radius sizes. Standard scoops are made of cast iron and for the 3 size a 13 or 19 feeder is supplied, for the 4 size a 30 or 36, for the 5 a 36 or 42, and for the 6 a 42 or 48 feeder. Welded steel scoop feeders can, however, be supplied in any radius.

The correct size of feeder depends upon the size of the classifier, and the smallest feeder should be used which will permit gravity flow for closed circuit grinding between classifier and the ball or rod mill. All feeders are built with a removable wearing lip which can be easily replaced and are designed to give minimum scoop wear.

A combination drum and scoop feeder can be supplied if necessary. This feeder is made of heavy steel plate and strongly welded. These drum-scoop feeders are available in the same sizes as the cast iron feeders but can be built in any radius. Scoop liners can be furnished.

The trunnions on Ball-Rod Mills are flanged and carefully machined so that scoops are held in place by large machine bolts and not cap screws or stud bolts. The feed trunnion flange is machined with a shoulder for insuring a proper fit for the feed scoop, and the weight of the scoop is carried on this shoulder so that all strain is removed from the bolts which hold the scoop.

High carbon steel rods are recommended, hot rolled, hot sawed or sheared, to a length of 2 less than actual length of mill taken inside the liners. The initial rod charge is generally a mixture ranging from 1.5 to 3 in diameter. During operation, rod make-up is generally the maximum size. The weights per lineal foot of rods of various diameters are approximately: 1.5 to 6 lbs.; 2-10.7 lbs.; 2.5-16.7 lbs.; and 3-24 lbs.

Forged from the best high carbon manganese steel, they are of the finest quality which can be produced and give long, satisfactory service. Data on ball charges for Ball-Rod Mills are listed in Table 5. Further information regarding grinding balls is included in Table 6.

Rod Mills has a very define and narrow discharge product size range. Feeding a Rod Mill finer rocks will greatly impact its tonnage while not significantly affect its discharge product sizes. The 3.5 diameter rod of a mill, can only grind so fine.

Crushers are well understood by most. Rod and Ball Mills not so much however as their size reduction actions are hidden in the tube (mill). As for Rod Mills, the image above best expresses what is going on inside. As rocks is feed into the mill, they are crushed (pinched) by the weight of its 3.5 x 16 rods at one end while the smaller particles migrate towards the discharge end and get slightly abraded (as in a Ball Mill) on the way there.

We haveSmall Ball Mills for sale coming in at very good prices. These ball mills are relatively small, bearing mounted on a steel frame. All ball mills are sold with motor, gears, steel liners and optional grinding media charge/load.

Ball Mills or Rod Mills in a complete range of sizes up to 10 diameter x20 long, offer features of operation and convertibility to meet your exactneeds. They may be used for pulverizing and either wet or dry grindingsystems. Mills are available in both light-duty and heavy-duty constructionto meet your specific requirements.

All Mills feature electric cast steel heads and heavy rolled steelplate shells. Self-aligning main trunnion bearings on large mills are sealedand internally flood-lubricated. Replaceable mill trunnions. Pinion shaftbearings are self-aligning, roller bearing type, enclosed in dust-tightcarrier. Adjustable, single-unit soleplate under trunnion and drive pinionsfor perfect, permanent gear alignment.

Ball Mills can be supplied with either ceramic or rubber linings for wet or dry grinding, for continuous or batch type operation, in sizes from 15 x 21 to 8 x 12. High density ceramic linings of uniform hardness male possible thinner linings and greater and more effective grinding volume. Mills are shipped with liners installed.

Complete laboratory testing service, mill and air classifier engineering and proven equipment make possible a single source for your complete dry-grinding mill installation. Units available with air swept design and centrifugal classifiers or with elevators and mechanical type air classifiers. All sizes and capacities of units. Laboratory-size air classifier also available.

A special purpose batch mill designed especially for grinding and mixing involving acids and corrosive materials. No corners mean easy cleaning and choice of rubber or ceramic linings make it corrosion resistant. Shape of mill and ball segregation gives preferential grinding action for grinding and mixing of pigments and catalysts. Made in 2, 3 and 4 diameter grinding drums.

Nowadays grinding mills are almost extensively used for comminution of materials ranging from 5 mm to 40 mm (3/161 5/8) down to varying product sizes. They have vast applications within different branches of industry such as for example the ore dressing, cement, lime, porcelain and chemical industries and can be designed for continuous as well as batch grinding.

Ball mills can be used for coarse grinding as described for the rod mill. They will, however, in that application produce more fines and tramp oversize and will in any case necessitate installation of effective classification.If finer grinding is wanted two or three stage grinding is advisable as for instant primary rod mill with 75100 mm (34) rods, secondary ball mill with 2540 mm(11) balls and possibly tertiary ball mill with 20 mm () balls or cylpebs.To obtain a close size distribution in the fine range the specific surface of the grinding media should be as high as possible. Thus as small balls as possible should be used in each stage.

The principal field of rod mill usage is the preparation of products in the 5 mm0.4 mm (4 mesh to 35 mesh) range. It may sometimes be recommended also for finer grinding. Within these limits a rod mill is usually superior to and more efficient than a ball mill. The basic principle for rod grinding is reduction by line contact between rods extending the full length of the mill, resulting in selective grinding carried out on the largest particle sizes. This results in a minimum production of extreme fines or slimes and more effective grinding work as compared with a ball mill. One stage rod mill grinding is therefore suitable for preparation of feed to gravimetric ore dressing methods, certain flotation processes with slime problems and magnetic cobbing. Rod mills are frequently used as primary mills to produce suitable feed to the second grinding stage. Rod mills have usually a length/diameter ratio of at least 1.4.

Tube mills are in principle to be considered as ball mills, the basic difference being that the length/diameter ratio is greater (35). They are commonly used for surface cleaning or scrubbing action and fine grinding in open circuit.

In some cases it is suitable to use screened fractions of the material as grinding media. Such mills are usually called pebble mills, but the working principle is the same as for ball mills. As the power input is approximately directly proportional to the volume weight of the grinding media, the power input for pebble mills is correspondingly smaller than for a ball mill.

A dry process requires usually dry grinding. If the feed is wet and sticky, it is often necessary to lower the moisture content below 1 %. Grinding in front of wet processes can be done wet or dry. In dry grinding the energy consumption is higher, but the wear of linings and charge is less than for wet grinding, especially when treating highly abrasive and corrosive material. When comparing the economy of wet and dry grinding, the different costs for the entire process must be considered.

An increase in the mill speed will give a directly proportional increase in mill power but there seems to be a square proportional increase in the wear. Rod mills generally operate within the range of 6075 % of critical speed in order to avoid excessive wear and tangled rods. Ball and pebble mills are usually operated at 7085 % of critical speed. For dry grinding the speed is usually somewhat lower.

The mill lining can be made of rubber or different types of steel (manganese or Ni-hard) with liner types according to the customers requirements. For special applications we can also supply porcelain, basalt and other linings.

The mill power is approximately directly proportional to the charge volume within the normal range. When calculating a mill 40 % charge volume is generally used. In pebble and ball mills quite often charge volumes close to 50 % are used. In a pebble mill the pebble consumption ranges from 315 % and the charge has to be controlled automatically to maintain uniform power consumption.

In all cases the net energy consumption per ton (kWh/ton) must be known either from previous experience or laboratory tests before mill size can be determined. The required mill net power P kW ( = ton/hX kWh/ton) is obtained from

Trunnions of S.G. iron or steel castings with machined flange and bearing seat incl. device for dismantling the bearings. For smaller mills the heads and trunnions are sometimes made in grey cast iron.

The mills can be used either for dry or wet, rod or ball grinding. By using a separate attachment the discharge end can be changed so that the mills can be used for peripheral instead of overflow discharge.

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

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

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