Difference between revisions of "Crushers"

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==Industrial use==
==Industrial use==
In the 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 Stage Crushers| primary]] and [[Secondary Stage Crushers| secondary]] crushers handling coarse materials, and [[Tertiary Stage Crushers |tertiary]] and [[Quaternary Stage Crusher|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 [[Screeners|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 [[Grinders|grinder]]. A typical circuit at a mine might consist of a crusher followed by a grinder SAG mill followed by a grinder [[Ball mill]]. In this context, the SAG mill and [[Ball mill]] are considered [[Grinders]] rather than crushers.
In the 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 Stage Crushers| primary]] and [[Secondary Stage Crushers| secondary]] crushers handling coarse materials, and [[Tertiary Stage Crushers |tertiary]] and [[Quaternary Stage Crushers|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 [[Screeners|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 [[Grinders|grinder]]. A typical circuit at a mine might consist of a crusher followed by a grinder SAG mill followed by a grinder [[Ball mill]]. In this context, the SAG mill and [[Ball mill]] are considered [[Grinders]] rather than crushers.


Crushers can be categorized in the way they are used in the industry (Continuous or per batch).  
Crushers can be categorized in the way they are used in the industry (Continuous or per batch).  
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==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]].




There can be also another stage of crushing called [[tertiary stage crushers|tertiary crushing]] depending on the initial size of the run of mine ore and the final product size requirement.  Different stages are required as total size reduction in one single crusher is not possible efficiently. Moreover smaller sizes of material  tend to jam the flow of ore in the crusher and unless there is  sufficient space for the crushed ore to expand in volume there will be  choking of the crusher. Hence [[Screeners|vibrating screens]] are deployed in between  different stages of the crushers so that only those oversize ore can be  fed to the crusher whose sizes need to be reduced. This also helps in  reducing the capacity requirement of the crusher as total run of mine  ore need not be fed to the crusher. Also there will be closed circuit  operation in case of secondary and tertiary crushers so as to avoid passing of any oversize material to the final stage. Primary crushing is done in open circuit only.  
There can be also another stage of crushing called [[Tertiary Stage Crushers|tertiary crushing]] depending on the initial size of the run of mine ore and the final product size requirement.  Different stages are required as total size reduction in one single crusher is not possible efficiently. Moreover smaller sizes of material  tend to jam the flow of ore in the crusher and unless there is  sufficient space for the crushed ore to expand in volume there will be  choking of the crusher. Hence [[Screeners|vibrating screens]] are deployed in between  different stages of the crushers so that only those oversize ore can be  fed to the crusher whose sizes need to be reduced. This also helps in  reducing the capacity requirement of the crusher as total run of mine  ore need not be fed to the crusher. Also there will be closed circuit  operation in case of secondary and tertiary crushers so as to avoid passing of any oversize material to the final stage. Primary crushing is done in open circuit only.  




Some [[Mobile crushers|crushers are mobile]] and can crush rocks (as large as 60 inches). Primarily used in-pit at the mine face these units are able to move with the large infeed machines (mainly shovels)to increase the tonnage produced.  In a mobile road operation, these crushed rocks are directly combined with concrete and asphalt which are then deposited on to a road surface.  This removes the need for hauling over-sized material to a stationary crusher and then back to the road surface.
Some [[Mobile Crushers|crushers are mobile]] and can crush rocks (as large as 60 inches). Primarily used in-pit at the mine face these units are able to move with the large infeed machines (mainly shovels)to increase the tonnage produced.  In a mobile road operation, these crushed rocks are directly combined with concrete and asphalt which are then deposited on to a road surface.  This removes the need for hauling over-sized material to a stationary crusher and then back to the road surface.


*[[Primary Stage Crushers]]
*[[Primary Stage Crushers]]
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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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