Crushing and screening is a necessary preparatory operation in the early stage of the beneficiation process, and has a great impact on the technical and economic indicators of grinding and beneficiation operations. Due to the differences in mining methods, transportation conditions and the size of the concentrator, the particle size of the raw materials sent to the concentrator is also different. At present, the maximum particle size of ore mined underground is 200600mm, and the maximum particle size of ore mined in open pit is 1200-1500mm. However, due to structural reasons, the currently used ore crushing equipment can handle a certain range of feeding particle size and product particle size, so it is impossible to crush the coarse ore blocks to the required selected particle size at one time. It must be crushed segment by segment through several different types of crushing equipment, and each segment only completes a part of the entire crushing process. The ore crushing adopts two-stage or three-stage crushing, or even four-stage crushing, while some small processing plants use one-stage crushing.

The ore crushing is divided into coarse crushing, the feeding size is 1500~300mm, the product size is 350~100mm, the medium crushing is 350~100mm, and the product size is 100~40mm; the fine crushing is 100~40mm, and the product size is 25~6nm. The crushing ratio is the ratio of the original particle size of the ore to the crushed particle size.