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[[Category:Particle Size Reduction]]{{Knoppen}} | [[Category:Particle Size Reduction]]{{Knoppen}} | ||
[[File:Impact_Crusher.jpg|thumb|right|Impact Crusher]] | [[File:Impact_Crusher.jpg|thumb|right|Impact Crusher]] | ||
[[File: | [[File:Jaw Crusher Principle.gif|thumb|right|Stationary Jaw Crusher]] | ||
[[File:VSI_Crusher_mobile.jpg|thumb|right|Mobile Vertical Shaft Impact Crusher]] | [[File:VSI_Crusher_mobile.jpg|thumb|right|Mobile Vertical Shaft Impact Crusher]] | ||
A '''Severe Duty 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 mortar and mortars are types of these crushing devices. | |||
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*[[Compact Crushers]] | *[[Compact Crushers]] | ||
*[[Portable Crushers]] | *[[Portable Crushers]] | ||
==Stages== | ==Stages== | ||
For the purpose of mineral extraction when ore is excavated from earth the size of run of-mine ore can vary a lot between fines powders to big boulders of 1.5 m across. Moreover the feed can also be intermittent type in the form of dumpers feeding the crushing plant. The crusher at this stage is called [[Primary Stage Crushers|primary crusher]] the main purpose of which is to give continuous feed to the plant down the line in a size convenient for further handling in the process plant. In the next stage further crushing may be required so as to ensure proper releasing of mineral from gangue. The crusher in this stage is called | For the purpose of mineral extraction when ore is excavated from earth the size of run of-mine ore can vary a lot between fines powders to big boulders of 1.5 m across. Moreover the feed can also be intermittent type in the form of dumpers feeding the crushing plant. The crusher at this stage is called [[Primary Stage Crushers|primary crusher]] the main purpose of which is to give continuous feed to the plant down the line in a size convenient for further handling in the process plant. In the next stage further crushing may be required so as to ensure proper releasing of mineral from gangue. The crusher in this stage is called | ||
[[Secondary Stage Crushers|secondary crusher]]. | [[Secondary Stage Crushers|secondary crusher]]. | ||
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==Technology== | ==Technology== | ||
For the most part advances in crusher design have moved slowly. Jaw crushers have remained virtually unchanged for sixty years. More reliability and higher production have been added to basic [[Cone Crushers|cone crusher]] designs that have also remained largely unchanged. Increases in rotating speed, have provided the largest variation. For instance, a 48 inch (120 cm) cone crusher manufactured in 1960 may be able to produce 170 tons/h of crushed rock, whereas the same size cone manufactured today may produce 300 tons/h. These production improvements come from speed increases and better crushing chamber designs. | For the most part advances in crusher design have moved slowly. Jaw crushers have remained virtually unchanged for sixty years. More reliability and higher production have been added to basic [[Cone Crushers|cone crusher]] designs that have also remained largely unchanged. Increases in rotating speed, have provided the largest variation. For instance, a 48 inch (120 cm) cone crusher manufactured in 1960 may be able to produce 170 tons/h of crushed rock, whereas the same size cone manufactured today may produce 300 tons/h. These production improvements come from speed increases and better crushing chamber designs. | ||
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==Types of Crushers== | ==Types of Crushers== | ||
Crushers can be divided in three groups: Attrition, Shear and Compression. | Crushers can be divided in three groups: Attrition, Shear and Compression. | ||
*[[Attrition Crushers]] | *[[Attrition Crushers]] |
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