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hammer mill crusher and screen deck

hammer mill crusher & grinder

hammer mill crusher & grinder

The hammer mill is the best known and by far the most widely used crushing device employing the impact principle of breaking and grinding stone. Thus far we have described machines which do a portion of their work by impact, but the only machine described in which this action plays an important role was the sledging roll type and particularly the Edison roll crusher and in these machines impact is supplemented to a substantial degree by a positive and powerful sledging action by teeth which are rigidly attached to massive rolls.

The hammermill, fundamentally, is a simple mechanism. The orthodox machine comprises a box-like frame, or housing, a centrally disposed, horizontal-shaft rotating element (rotor) on which the hammers are mounted, and usually a set of circumferentially arranged grates in the lower part of the housing. The rotor consists of a shaft carried in bearings at either side of the housing, and the hammer centre of multi-flange drum or spool shape. The flanges of this drum-like assembly are drilled near their outer edges for hinge pins to which the inner ends of the hammers or hammer arms are attached. The hammers themselves are made in a variety of styles and shapes. Sometimes the hammer arm and head are cast, or forged, integrally; in other designs as in the impactorthe arms and hammer head are separate pieces.

The grates usually consist of a transversely arranged series of tapered, wear-resisting steel bars, which form a cage of circular cross section across the lower part of the housing just below the hammer path. The spacing of these steel bars varies quite widely, depending upon the size of product and upon the characteristics of the material to be crushed. The spacing may be anything from % in. or slightly less, up to several inches, and in some machines may be dispensed with entirely for coarse products and closed-circuit operation.

Hammermills may be connected directly to the driving motor, or driven by a flat belt or V-belts. The two latter methods have one material advantage over the direct drive; they permit speed adjustments to achieve optimum performance for each particular set of conditions.

In the impact-hammer-mill, a cross-sectional view of which is shown here on the left,the process is, in one important respect, a reversal of that just described. The material enters the machine on the up-running side of the rotor, where it is struck by the hammers as they start their sweep across the upper part of the housing. The top of the crushing chamber is lined with a series of breaker plates whose impact faces are involute with respect to the hammer circle, so that material hurled by the hammers impinges squarely against these surfaces regardless of the striking point. The action in this impact zone is a succession of violent blows, first from hammer-to-material and then from material-to-breaker plate, and so on through the several stages of the involute series. As contrasted to the type previously described, most of the work in this crusher is done in the breaker-plate zone; the grates function chiefly as a scalping grizzly, and the clearance between hammers and grates is relatively large. A certain amount of impact breaking does take place between hammers and grates, but this is secondary to the work done against the involute plates. On friable material this machine will deliver a medium fine (0.25 to 3/8) product with some, or even all, of the grates removed.

The capacity of any given size and type of hammermill depends upon several factors. The character of the material influences the performance of this machine to a greater degree than it does that of any of the crushers previously discussed. It is only natural that this should be the case; all of the energy consumed in the crushing chamber is delivered by free-swinging hammers, and it is to be expected that there would be a considerable difference in the effect of these impact blows upon materials of varying physical structure. Higher speeds will of course produce better shattering effect to take care of hard rock, but there are definite limits, both from mechanical and operational standpoints, to the speed of any particular mill.

Speed, or velocity, while it is the very life of the hammermill, may also function to limit the amount of feed that the mill will take. Thus, in any given machine, the number of rows of hammers used will affect capacity. Or, to state it a little more clearly, for any combination of speed, feed size, and number of rows of hammers there is a definite limit to the amount of material that the mill will receive.

This is understandable when it is considered, for example, that in a machine running 1500 RPM, with four rows of hammers, the receiving opening is swept by a row of hammers 100 times each second, and there is obviously a limit to the amount of material that can enter the space between two successive hammer rows in this short period of time.

We find that for some combinations of feed size and product size, more production can be obtained with only two rows of hammers, rather than three, or more. Radial velocity of the material entering the mill will naturally have a direct bearing upon the amount that will drop in between the rows of hammers. Thus, in a well designed mill the feed spout is always so arranged that the material falls, rather than flows, into the crushing zone.

It is hardly necessary to state that the size of product directly affects the capacity of a hammermill, just as it does any type of crusher. The finer the product the more work the machine must do; furthermore, the grate bars, when any are used, must be spaced closer, which means that the open area of the grate section is reduced.

When the grate bars are spaced widely, or dispensed with, and the sizing is done over a closed-circuited screen, product size has the same direct influence upon capacity because, the finer the screen openings, the more return load and, hence, the less original feed that can be handled by the mill.

Size of feed affects capacity, but not always in the inverse proportion which might, at first thought appear to be logical. For example, suppose we were operating a medium-size hammermill on limestone, turning out a 10-mesh product. We know that this machine will handle more tonnage if we feed it with, say, 3 maximum size rock, as compared with a feed of 10 or 12 maximum size; which accords with the logical expectation. However, if we further reduce the feed size to, say 12 maximum, we find that our will increase very little if at all; in fact it may actually decrease. This apparent anomaly is explained by the fact that the effect of impact upon a free body of material varies directly with the mass of the body; consequently the energy absorption, and hence the shattering effect, is much greater on the 3 piece than it is on the 1/2 particle.

Because all these variables that we have noted have an influence upon the capacity of the hammermill, it is impossible to present a comprehensive tabulation of capacity ratings which can be relied upon for any and all materials. We can however do so for any one material, as we did for the Fairmount crusher. It is convenient and logical that this should be a medium limestone in this case also, because hammermills are applied extensively to crushing, and pulverizing, that kind of rock.

Above is theapproximate capacity ratings of the various sizes of hammermill (impact crushers), on medium limestone, and for various grate bar spacings. Unless the prospective hammermill user has operational data on which to predicate his selection of a new machine for some specific service, the safest procedure is to have his material tested, either in the field or in the laboratory, in a mill of the type he proposes to install.

The shattering effect of the blows delivered by hammers travelling at velocities as high as 200 Feet/Second is conducive to both of these results. It is natural to expect that gradation of the hammermill product would vary somewhat for materials of differing friability, and results verify this expectation. Furthermore, speed has a definite influence upon product gradation; high speeds increase fines, and vice versa. The effect of impact at extremely high speed is, on friable material, almost explosive, the action being more aptly designated as pulverizing, rather than crushing. Lower impact velocities have a more moderate breaking effect, and if the material is able to clear the crushing chamber before it is struck too many times, the low speed hammermill will turn out a fairly uniformly graded product on material of average friability.

The design of the crushing chamber will also affect product gradation. In general, those machines which perform most of their work by straight impact action will turn out a more uniformly graded product than mills which depend upon interaction between hammers and grates for most of their reduction. This is only natural in view of the fact that attritional grinding is minimized in the former type of mill.

What is intended to take place inside a hammermill is the uniform, efficient reduction of the material introduced into the grinding chamber. This particle reduction occurs as a result of the impact between a rapidly moving hammer and a relatively slow moving particle. If sufficient energy is transferred during the collision, the particle breaks and is accelerated towards the screen. Depending on the particle size and the angle of approach, it either passes through the screen or rebounds from the screen into the rapidly moving hammers again. As materials move through the grinding chamber they tend to approach hammer tip speed. Since reduction only occurs when a significant energy is transferred from the hammer to the particle (large difference in velocities), less grinding takes place when the particles approach hammer tip speed. Many manufacturers incorporate devices within their mills to interrupt this product flow, allowing impact and reduction to continue. Tear circle hammermills have a more positive, natural redirection of product at the inlet than full circle design machines. While the basic operational concepts are the same for all hammermills, the actual unit operating conditions change rather dramatically depending on the materials being processed. Grains such as corn, wheat, sorghum and various soft stocks, like soybean meal, tend to be friable and easy to grind. Fibrous, oily, or high moisture products, like screenings, animal proteins, and grains like oats and barley, on the other hand, are very tough and require much more energy to reduce.Consequently, the hammermill setup that works well for one will not necessarily work for the other. The following discussion covers such factors as tip speeds, hammer patters and position, horsepower ratios (to hammer and screen area), and air assist systems. Little space is devoted to screen sizes (perforation or hole size) since processing variables would make any hard and fast statements nearly impossible.

The Jeffrey Swing is a relatively small Hammermill Pulverizer and is made in several types and a large number of sizes for handling large or small capacities and light, medium, or heavy work. Some of the materials being successfully reduced by this pulverizer are coal, coke, copper ore, barytes, gypsum, kaolin, magnesite, chalk, clay, cement rock, dolomite rock, phosphate rock, and limestone.

This machine operates on the principle of reducing the material by striking it while in suspension, as opposed to attrition. The material is fed into the top of the machine and falls into the path of the rapidly revolving hammers. Different degrees of reduction may be had by simply varying the speed of the machine.

This unit is of extra heavy construction and consequently is well adapted for severe duty. The hinged breaker plate is adjustable while operating and is fitted with a heavy renewable liner. Shafting is high carbon forged steel and is fitted with discs which are of heavy plate and cast steel, carefully balanced. Screen bars may be high carbon steel, tool steel, or manganese steel as desired. Jeffrey Swing Hammer Pulverizers have heavy cast iron frames and are lined with renewable chilled iron liners. Hammers are made of materials best suited for the particular job. Highest grade radial ball bearings are used and they are readily accessible for inspection and oiling. This keeps power consumption to a minimum and maintenance and repair part costs are extremely low, even for most types of heavy duty.

A metal catcher attachment is available for use on all sizes of pulverizers where tramp iron may be encountered. It may be specified when unit is ordered or obtained later and installed when need arises.Let us make recommendations for your pulverizer installation. Information required is type of material to be handled, tonnagesize of feed, and desired size of product. Belt or motor drive maybe used as required.

hammer mill operating principle

hammer mill operating principle

Operational Characteristics:The method of operation has a considerable effect upon the nature of the product. When minimum fines are a requirement, the hammer mill should always he operated in closed circuit with a screen, or screens; the circulating load should be fairly high; speed should be as low as is consistent with physical structure of the material; and grates should be widely spaced or, in some cases, dispensed with entirely.

Although the hammer mill usually produces a relatively high percentage of fine material, it does not usually make an inordinately high proportion of what are commonly designated as extreme-fines unless the mill is adjusted and operated with that end in view. For example, if we are turning out a 0.75 (top size) product in one of these machines we will usually find the proportion of particles in the range between 0.25 and about 30 or 40 mesh to be high, as compared to the product of pressure-type crushers; but unless the material is very friable and the natural grain size very fine the percentage of minus 100- and 200-mesh particles will usually compare quite closely. Here again we have the fact that the impact effect falls off directly with the particle mass, to explain an apparent inconsistency.

It is easy to understand why the hammermill should turn out a cubical product. The impact action is ideally adapted for breaking flat or elongated spalls. If the material contains numerous parallel cleavage planes the initial blows delivered by the hammers may knock off flat spalls; but the chances are very much against such spalls getting out of the machine before they are struck several times and broken into particles of more cubical proportions.

This is especially true of machines which have a long impact zone ahead of the grate section, as no particle can possibly be discharged until it has passed through this impact section, where it will almost certainly be struck several blows.

Hammermills are capable of accomplishing: reductions very muchgreater than any other type of crushing equipment. It is possible, though not always economical, to make reductions as high as 20:1 in open circuit, and to double this performance in closed circuit. As in any other type of crusher, low reduction ratios are indicated where a low percentage of fines is desirable.

Time was when all hammermills came under the generic title of pulverizer which was quite appropriate as it aptly described the kind of work to which they were, in those days, almost exclusively applied. This duty consisted largely of such work as pulverizing limestone for various purposes: agricultural flour, glasssand, tube mill feed, and so forth. This was work for which the hammermill was and still pre-eminently well suited, and large numbers of them are used today for such service. The field has however in recent years been greatly expanded. The following list, while not comprehensive, includes some of the more important present day applications:

Not all of the uses listed can, in our opinion, be considered as economically sound applications for the hammermill. This machine cannot be expected to operate economically on abrasive feed, and it should not be so applied unless there are strong reasons for doing so. Generally this narrows itself down to cases where no other type of crusher will deliver the type of product required; occasionally the high reduction ratio of which they are capable will dictate their use in temporary jobs where the cost of a two-stage set-up of more economical operating characteristics would more than offset the cost of the single hammermill plus the expected cost of maintenance. A case in point to illustrate the latter condition is that of pilot plant testing in the development of new mining properties.

Sectional view shows how material is broken down in one type of hammermill. Material is fed to an inclined plate which is fastened to the hopper over the feed opening. This plate is so arranged that the material is evenly distributed and fed uniformly to the mill. The rapidly revolving hammers (see arrows indicating direction of rotation) strike the material a succession of heavy blows, shattering it and throwing it violently against the first involute breaker plate. Striking this plate with great farce, the material is again shattered and, as it rebounds, it is struck again and carried ta a second involute breaker plate from where it again rebounds and so on through five stages. The pulverized product passes out through grate bars In the bottom of the machine

We have never subscribed to the idea that the hammermill is suited to the primary breaking of shovel-loaded, quarry-run, or ROM mine-run rock and ore. Even though the material be non-abrasive and quite friable there are other machines which are better fitted for such work. Nor do we believe that the hammermill has a place in any of the stages of a plant intended for the production of commercial crushed stone unless the production of a high percentage of fines is not objectionable; a rather rare condition for operations of this character. These legitimate restrictions still leave quite a broad field for this ma-chine, and it is probable that more applications will crop up from time to time as our chemical industries grow.

Examination of cement plant flowsheets, discloses that, at that time, only six of these plants employed hammermills, and two of these were used in the shale crushing department. Today the hammermill is widely accepted as a secondary or tertiary crusher in cement plants throughout the country; and there are isolated instances where they perform the primary breaking as well.

The Pulverator/Impactor/Hammermill/Impact-Crusher was successfully applied to the production of manufactured sand for concrete aggregates used in the construction of a large dam in one of the eastern states. This application was made after crushing rolls had been tried and discarded because their product ran so heavily to flat spalls that a workable concrete could not be made with it. We mention this case as being indicative of the ability of the hammermill to cube material, even though the rocks physical structure is conducive to spalling or flaking. Subsequent installations for the same purpose have been equally successful.

The Dixie (Non-Clog) Hammer Mill Crusher differs from all other hammermills in that its breaker plate, instead of being stationary, is a continuously moving belt of manganese steel links. The feed thrown into the hopper is carried by a positive mechanical feed to the hammer-points and then on through the grates.

The most important results from the installation of the Dixie (Non-Clog) Hammermill are the uniform high quality of the product and the enormous crushing power, which, with reduction range of this mill, eliminate the necessity of using several units to obtain the necessary production.

The Dixie (Non-Clog) Hammermill is manufactured in fourteen different sizes, adapted to reduction of any materials containing moisture without clogging. Due to various adjustments this equipment is capable of crushing to a minimum of fines or pulverizing to a maximum of fines. The adjusting features are exclusive Dixie patents.

The non-clog moving breaker plate is a patented feature found only in Dixie Hammermills, positively eliminating all troubles and loss of production from wet or sticky materials that would continually clog any other type crusher or pulverizer. It is capable of crushing potash, salt, mica, limestone, gypsum, coal, or any similar soft material not exceeding 4 on the Mohs scale of hardness.

The Jeffrey Miracle Hammer Crusher is designed for the reduction of large pieces and large capacities of limestone, shale, slag, and cement rock. The larger sizes are built to take steam shovel size limestone, crushing it into pieces 1, 2, 3, or 4 and under, in one operation, the one unit doing the work ordinarily done by two or more of other types of crushers. This enables large reduction of limestone and other materials to a uniform size with minimum initial and production costs. All parts are extra heavy to withstand heavy, continuous service. The Miracle Hammer Crushers are supplied with either heavy cast iron frames or with armor-plate steel frames with manganese steel liners. These crushers are provided with a hinged breaker plate easily adjustable to compensate for wear, as well as giving easy access to working parts. The large, heavy duty crushers are frequently used in such industries as carbide, chemical and cement as a primary machine where large capacities and cubical products are desired.

The Jeffrey Heavy Duty Reversible Hammer Crusher is designed especially for reducing bituminous coal down to a product of 85% minus 1/8, at large capacities, for coking purposes. These machines are also adaptable to the reduction of abrasive materials since they are symmetrical about the vertical center line and when one corner of the hammers become worn, it is only necessary to reverse the direction of the rotor in order to use the opposite unused faces of the hammers. The frame is made of heavy welded plate steel equipped with removable manganese liners and provided with vertical hinged breaker plates to compensate for the wear on breaker plate liners.

hammer mill | henan deya machinery co., ltd

hammer mill | henan deya machinery co., ltd

A hammer mill is a mill whose purpose is to shred or crush aggregate material into smaller pieces by the repeated blows of little hammers. The basic principle is straightforward. A hammer mill is essentially a steel drum containing a vertical or horizontal rotating shaft or drum on which hammers are mounted. The hammers are free to swing on the ends of the cross, or fixed to the central rotor. The rotor is spun at a high speed inside the drum while material is fed into a feed hopper. The material is impacted by the hammer bars and is thereby shredded and expelled through screens in the drum of a selected size. The hammer mill can be used as a primary, secondary, or tertiary crusher(via wikipedia).

crushers - jh equipment

crushers - jh equipment

The purpose of all crushers are the same, to reduce oversized product to powder so that it can be recycled back into theproduction process. There are many types of crushers available on the market for many different product types and industries. It is important to look at the crusher that is correct for your product. Except for the lump breaker, the basis of the J&H Crusher is the dual rotor chain mill for most applications, and in forty years, we have not swerved from this base. Why?

Chain mills are simple machines. The ability of the machine to function at full potential does not depend on the flatness of any surface, on the spacing of two rollers in rotation, or the amount of pressure applied. The principle of the chain mill only relies on the laws of physics of impact. For most friable materials, the efficiency isexcellent because the physics works in our favor to produce a consistent discharge particle size distributionlargely independent of theparticle size distribution at the feed.

For roller crushers, if there is any moisture content to the product, the product will not crush, but will flatten into little disk that are not easy to screen out. This can significantly reduce the quality of your product.Another disadvantage of theroller mill is that product clumps larger than a certain size will not easily pass into the rollers to get crushed, but maysimply roll on top of the two rollers, blocking the product flow. In a J&H Chain Mill, the larger clumps do not stand a chance against the high speed impact of a link of hard steel chain. J&H Chain mills work in a large variety of applications and with a large range of product materials and product quality.

The chain millis forgiving to normal wear and is relatively inexpensive to maintainin alike new condition, only needing to periodically replace links of chain or liner material. Critical components such as the bearings and drive systems are exterior to the mill housing for convenient inspection and maintenance. Development of our rubber impact pads have significantly reduced or eliminated material build-up on the interior of the chain mill housing and have extended the working life of the chain mill. Full width side access doors andthe open interior of our chain millsmeans that it isvery easy to get access to all parts of the mill for maintenance. Chain link replacement can be performed with the rotors in place in the machines. The open environment of the interior also means that foreign materials circulating in the product stream will pass through the mill with little notice while other machines that require the material to pass through narrow passages may become damaged or clogged.

J&H Chain mill rotors are dynamically balanced and our unique support system means that vibration of the chain mill housing is negligible for all normal operating conditions. The machines are available in five different sizes and the compact footprint allows for the mills to be near each other for nearly any plant production capacity from 5 Tons per hour to over 600 Tons per hour per production line.

J&H has a line of custom mills for specific applications. The are usually single rotor mills, either horizontal or vertical, but may also be modified dual rotor chain mills. The impact surface may be chain links, hammers, or blades depending on the abrasiveness and hardness of the product material.

Hammer mills use rotors loaded with AR400 hammer flails to pulverize the product material. The increased crushing surface area and the unique single rotor design makes it different then its chain mill counterpart.

hammer crusher | hammer mill crushers for sale jxsc mine

hammer crusher | hammer mill crushers for sale jxsc mine

Hammer Crusher Application Field Mining, metallurgy, building material, cement, quarrying, gravel & sand making, aggregate processing, recycling, and chemical industry, etc. Suitable Material Limestone, slag, pebble, rock gold ore, salt, concrete, coal, coke and other materials in the primary/secondary crushing and fine crushing operations.

Hammer stone crusher is a kind of equipment that crushes materials in the form of impact. Crushing the size of 600-1800 mm material to 25m or less. Hammermill machine can not only be used in stone crusher plant, sand plant, but also can replace the cone crusher in the mineral processing.

JXSC hammer mill machine that hammerhead adopts a new technology cast which wear-resistant and impact-resistant. The airframe structure of the hammer mill is seal which solves the problems of dust pollution and dust leakage in the crushing workshop. And it is easy to maintain.

1. Hammerhead uses new cast technology which with wear-resistant and impact-resistant characteristic. 2. Can adjust the granularity size. 3. The seal structure that solves the problems of dust pollution and dust leakage in the crushing workshop. 4. The overall design of hammer crushing equipment has the advantages of beautiful appearance, compact structure, few wearing parts, convenient maintenance, etc.

Hammermill crusher mainly rely on impact energy to complete the crushing of materials. When the hammer mill rock crusher works, the motor drives the rotor to rotate at high speed, and the material enters the crusher cavity evenly. The hammerhead with high speed turns impacts and tears the material lead to the materials are crushed.

At the same time, the material from the high-speed rotating hammerhead to the baffle and screen strip in the frame under the gravity effect. The material larger than the size of the screen hole remains on the screen plate and continues to be hit and ground by the Hammer. Then finally through the sieve plate discharge machine until the crusher material size discharge.

The advantages of the hammer: The ratio of crushing is large, generally is 10-25, high up to 50. High production capacity. uniform products. Less over-powder phenomenon. Simple structure, light equipment quality. Simple operation and maintenance, etc. The series hammer crusher products are suitable for crushing all kinds of medium hardness and brittle materials, such as limestone, coal, salt, gypsum, alum, brick, tile, coal gangue and so on. The compressive strength of the crushed material shall not exceed 150 MPA.

The series of crushers are mainly used in cement, coal preparation, power generation, building materials, and compound fertilizer industries. It can crush the raw materials of different sizes into uniform particles for the next working procedure. Reliable mechanical structure, high production efficiency, good applicability.

But the hammer crusher also has some disadvantages, such as the hammer and grate screen wear quickly. When crushing hard materials, they wear out faster. When crushing sticky wet materials, it is easy to plug the screen seam of the grate. Therefore, it is easy to cause shut down, so the moisture content of the material should not exceed 10 %. When milling hard objects, the hammer and lining plate have big wear. And the consumptive metal material is much, often needs to replace the wear-and-tear piece.

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

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