How to choose a crusher based on material particle size


As we all know, the process of reducing materials from large pieces to smaller pieces is called crushing. Generally, external force is applied to overcome the cohesion between materials and cause the materials to break. Crushing plays an important role in industrial sectors such as mineral processing, chemical industry, and building materials. At present, the production cost of crushing and grinding in the mineral processing plant accounts for more than 40% of the total mineral processing cost. The investment in crushing and grinding accounts for about 60% of the total investment in the mineral processing plant. Therefore, it is of great significance to improve crushing productivity and reduce crushing power consumption. According to the different particle sizes of crushed raw materials and products, the crushing operation can be roughly divided into five stages, namely: 1) coarse crushing; 2) medium crushing; 3) fine crushing; 4) coarse grinding; 5) fine grinding.

Due to the different methods, transportation conditions and size of the mineral processing plant, the particle size of the raw materials sent to the mineral processing plant is also different. At present, the maximum size of ore mined underground is 400~600 mm, while that of ore mined in the open pit is 1200~1500 mm. The particle size required for mineral processing operations often needs to be crushed to 1~0.06 mm. According to the current conditions of mechanical equipment, it is not possible to rely only on one set of crusher machines to crush the materials to the required fineness at one time. It needs to be done section by section. If it is a large-scale open-pit mining mine, the largest block sent to the mineral processing equipment can reach 1200~1500 mm, then the approximate particle size range of each section is:

(1) Coarse crushing: 1500~300 mm;

(2) Medium crushing: 300~75 mm;

(3) Finely crushed: 75~10 mm;

(4) Coarse grinding: 10~1.0 mm;

(5) Fine grinding: 1.0~0.075 mm.

If underground mining or small and medium-sized mines are used, when the maximum particle size of raw ore is about 300 mm, the approximate particle size range of each section is:

1) Coarse crushing: 300~75 mm.

2) Medium crushing: 75~25 mm.

3) 25~8 mm.

After each stage of crushing, the particle size of the material will be reduced to a certain extent. The ratio of the maximum diameter of the material before crushing to the maximum diameter of the product after crushing is the crushing ratio. The so-called maximum block diameter of a material is often expressed as the size of the sieve hole that can pass 95% of the material.

The crushing ratio can indicate how many times the material is reduced by the crusher in this section. Therefore, sometimes the ratio of the maximum ore feeding particle size of the crusher to the size of the ore discharge port becomes the crushing ratio. It is one of the weight working indicators of the crusher. It depends on the structural characteristics of the crusher. For example, the current commonly used coarse crushing jaw crusher has a crushing ratio of 3 to 5, the medium crushing standard cone crusher has a crushing ratio of 4 to 6, and the fine crushing short head cone crusher has a crushing ratio of 3 to 5. wait.

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