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Majda Rumzan

5/14/14

Hammer mill : zzz Introduction:The hammer mill crusher is developed for both dry and wet crushing of brittle, medium-hard materials for the mining, cement, coal, metallurgic material, construction material, road building, and petroleum & chemical industries. The hammer crusher machine crushes by the collisions between high-speed hammer and material, and the hammering machine has the features of simple structure, high reduction ratio, high efficiency, etc.

The hammer crusher (hammer mill) crushes by the collisions between high-speed hammer and materials and the hammer crusher (hammer mill) features in its simple structure, high reduction ration, high efficiency, etc. The PC hammer crusher were developed for both dry and wet crushing of brittle, medium-hard materials for the mining, cement, coal, metallurgic, construction material, road building, and petroleum & chemical industries.

Construction:The mills are of exceptionally robust construction with a body in thick mild steel plate. The heavy-duty rotor is fitted with large four-way reversible hammers in tempered steel. The rotor has a large diameter shaft running in special double roller heavy-duty roller bearings.

Operating principle:The motor drives the rotor rotate at a high speed through the belt, and on the rotor there are series hammers. When the materials get into the working area of hammers, they are crushed by the rotating hammers with high rotation speed, the products which are crushed to meet the required size can be discharged by the outlet and become the final products, the large size products are brought back to the crushed area by the hammers for being re crushed until they reached the required size. In the milling chamber, the hammers rotating at high speed pulverize the material into particles small enough to be drawn through the screen by the fan. Milled material is conveyed pneumatically into the collection cyclone from where it is discharged into a suitable receptacle. Fine dust from the top of the cyclone is trapped by the filters.

Features:1. Simple and reasonable structure, low operation cost.

2. High efficiency and energy saving.

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3. Fine grinding function.4. Slightly influenced by humidity, the max, humidity could reach 15%.

5. suitable for crushing mid-hardness and high-hardness materials.

Working:Hammer mill works on the principle that most materials will crush, shatter, or pulverize upon impact using a simple four step operation:

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1. Material is fed into the mill’s chamber typically by gravity.

2. The material is struck by ganged hammers (generally rectangular pieces of hardened steel) which are attached to a shaft which rotates at a high speed inside the chamber.  The material is crushed or shattered by the repeated hammer impacts, collisions with the walls of the grinding chamber as well as particle on particle impacts.

3. Perforated metal screens, or bar grates covering the discharge opening of the mill retain coarse materials for further grinding while allowing properly sized materials to pass as finished product.

4. Hard, heavy materials such as glass, stone or metals exit the mill via gravity. Pneumatic suction is used to assist in the discharge of lighter materials such as wood, paper or other low bulk density products. 

Varying the screen size, shaft speed or hammer configuration can dramatically alter the finished size of the product being ground.  For example, faster speed, a smaller screen, and more hammers result in a finer end product.  Each component can be changed individually or in any combination to produce the precise grind required.  All of this is determined by taking advantage of our free test grinding service.

Advantages of hammer mill:

Hammer mill has following advantages: 1.It can once moldings, don't need a second fracture process. So it can cut the cost. 2. It also can crush the wet stone, you can add water to reduce the dust pollution when crushing, it could protect worker’s health and keep a good environment. 3. We adopt durable parts, especially the PCZ series heavy hammer crusher, compared to speak, it is more durable than the jaw crusher and impact crusher. We use the alloy hammer, the cast steel

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parts to guarantee the function and its life. 4. We have many types, the capacity ranges from 50t/h to 800t/h so than meet the clients’ requirement. 5. The outlook design and the strengthened intrinsic quality make the performance to be more superior.

These impact crushers are the most effective method developed for crushing, grinding or pulverizing. The hammer mill crushers operate with a rain of hammer or ring blows which shatter and disintegrate the material being reduced. Size reduction hammer mills provide a finish product size that is dependent upon the size of openings in perforated screens; the number, size and type of hammers;

the setting of adjustable grinding plates and the speed of the rotor.

Applications:

A hammer mill is a machine whose purpose is to shred or crush aggregate material into smaller pieces. These machines have many sorts of applications in many industries, including:

Ethanol plants (corn) A farm machine, which mills grain into coarse flour to be fed to livestock Fluff pulp production Fruit juice production Grinding used shipping pallets for mulch Milling grain Saw mills, size reduction of trim scrap and planer shavings into boiler fuel or mulch

Shredding paper Shredding scrap automobiles Shredding yard and garden waste for compositing Crushing large rocks In waste management

Disadvantages of Hammer mill: For fine reduction, hammer mill is limited to softer materials. Capacity and power requirement vary greatly with nature of feed. It cannot be estimated with confidence from theoretical considerations. Less energy efficient when compared to a roller mill. May generate heat (source of energy loss). Produce greater particle size variability (less uniform).

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Hammer mills are noisy and can generate dust pollution. High energy cost needed which is not economical. In step grinding hammer mill, operation is more complicated to maintain.

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