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Crusher In Wikipedia

A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, or rock dust.Crushers may be used to reduce the size, or change the form, of waste materials so they can be more easily disposed of or recycled, or to reduce the size of a solid mix of raw materials (as in rock ore), so that pieces of different composition can be differentiated.Crushing is the process of transferring a force amplified by mechanical advantage through a material made of molecules that bond together more strongly, and resist deformation more, than those in the material being crushed do.Crushing devices hold material between two parallel or tangent solid surfaces, and apply sufficient force to bring the surfaces together to generate enough energy within the material being crushed so that its molecules separate from (fracturing), or change alignment in relation to (deformation), each other.The earliest crushers were hand-held stones, where the weight of the stone provided a boost to muscle power, used against a stone anvil.Querns and mortars are types of these crushing devices.In industry, crushers are machines which use a metal surface to break or compress materials.Mining operations use crushers, commonly classified by the degree to which they fragment the starting material, with primary and secondary crushers handling coarse materials, and tertiary and quaternary crushers reducing ore particles to finer gradations.Each crusher is designed to work with a certain maximum size of raw material, and often delivers its output to a screening machine which sorts and directs the product for further processing.Typically, crushing stages are followed by milling stages if the materials need to be further reduced.Crushers are used to reduce particle size enough so that the material can be processed into finer particles in a grinder.A typical circuit at a mine might consist of a crusher followed by a sag mill followed by a ball mill.In this context, the sag mill and ball mill are considered grinders rather than crushers.In operation, the raw material (of various sizes) is usually delivered to the primary crusher's hopper by dump trucks, excavators or wheeled front-end loaders.A feeder device such as a conveyor or vibrating grid controls the rate at which this material enters the crusher, and often contains a preliminary screening device which allows smaller material to bypass the crusher itself, thus improving efficiency.Primary crushing reduces the large pieces to a size which can be handled by the downstream machinery.Some crushers are mobile and can crush rocks (as large as 16 inches), concrete and asphalt into material as it is driven over material on road surface, thus removing the method of hauling oversized material to a stationary crusher and back to road surface.They are used, for example in road constructions.A jaw or toggle crusher consists of a set of vertical jaws, one jaw being fixed and the other being moved back and forth relative to it by a cam or pitman mechanism.The jaws are farther apart at the top than at the bottom, forming a tapered chute so that the material is crushed progressively smaller and smaller as it travels downward until it is small enough to escape from the bottom opening.The movement of the jaw can be quite small, since complete crushing is not performed in one stroke.The inertia required to crush the material is provided by a weighted flywheel that moves a shaft creating an eccentric motion that causes the closing of the gap.Jaw crusher single and double toggle jaw crushers are constructed of heavy duty fabricated plate frames with reinforcing ribs throughout.The crushers components are of high strength design to accept high power draw.Manganese steel is used for both fixed and movable jaw faces.Heavy flywheels allow crushing peaks on tough materials.Double toggle jaw crushers may feature hydraulic toggle adjusting mechanisms.Cone crusher a cone crusher is similar in operation to a gyratory crusher, with less steepness in the crushing chamber and more of a parallel zone between crushing zones.A cone crusher breaks rock by squeezing the rock between an eccentrically gyrating spindle, which is covered by a wear resistant mantle, and the enclosing concave hopper, covered by a manganese concave or a bowl liner.As rock enters the top of the cone crusher, it becomes wedged and squeezed between the mantle and the bowl liner or concave.Large pieces of ore are broken once, and then fall to a lower position (because they are now smaller) where they are broken again.This process continues until the pieces are small enough to fall through the narrow opening at the bottom of the crusher.A cone crushers is suitable for crushing a variety of mid-hard and above mid-hard ores and rocks.It has the advantage of reliable construction, high productivity, easy adjustment and less cost in operation.The spring release system of a cone crusher acts an overload protection that allows tramp to pass through the crushing chamber without damage to the crusher.Impact crushers impact crushers involve the use of impact rather than pressure to crush material.The material is contained within a cage, with openings on the bottom, end, or side of the desired size to allow pulverized material to escape.This type of crusher is usually used with soft and non-abrasive material such as coal, seeds, limestone, gypsum or soft metallic ores.There are two types of impact crushers: horizontal shaft impactor and vertical shaft impactor.

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