rushing operations are generally divided into two or three stages, depending on the hardness and size of the material being processed. In two-stage crushing operations, the material is first crushed to a smaller size using a primary crusher, and then further reduced in size using a secondary crusher. Three-stage crushing involves an additional stage of crushing using a tertiary crusher to further reduce the size of the material.
In the crushing process, to avoid collapse and reduce costs, the principle of “more crushing and less grinding” should be applied as much as possible.
In ore dressing plants, crushing operations are generally divided into two or three stages. Depending on the particle size of the crushed product, it can be roughly classified as coarse crushing, medium crushing, and fine crushing.
Coarse crushing: Feed size is 1500-500mm, crushed to 400-125mm, such as jaw crusher, hammer crusher.
Medium crushing: Feed size is 400-125mm, crushed to 100-50mm, such as impact crusher, spring cone crusher, hydraulic cone crusher.
Fine crushing: Feed size is 100-50mm, crushed to 25-5mm, such as cone crusher, single-cylinder cone crusher, etc.
Other crushing: Sand making with a feed size of 40-10mm, crushed to less than 5mm, such as sand making machine, double roll crusher, composite crusher.
Crushing and grinding are preparatory operations before selection. The prerequisite for beneficiation is to separate the useful minerals in the ore into monomers. Since the particle size of useful minerals as monomers is very small, sometimes it is necessary to grind the ore to a fineness of less than 0.074mm, which accounts for 80%, or even finer, to achieve monomer separation of certain useful minerals.
The size of the ore coming out of the stope is very large. For example, the ore supply size in open-pit mining can be as large as about 1000mm. Therefore, ore blocks as large as 1000mm must be crushed to only a few tens of microns (1 micron = 1/1000 millimeters) in several stages.
Regarding crushing, large-scale concentrators generally use coarse, medium, and fine three-stage crushing (four-stage crushing is also used) to gradually reduce the size of the lump ore to about 8mm, and then send it to the grinding machine for grinding until the useful mineral particles achieve monomer separation.