Superfine pulverization—the unit operation of grading has the following types of processes:
(1) Open-circuit crushing This type of process can be used for jet mills with internal hierarchical structures, such as flat jet mills, LCF fluidized bed jet mills, etc. The advantage is that the process is simple, and the disadvantage is that the classification efficiency is low.
(2) Closed-circuit pulverization Such as stirring mills, vibrating mills, etc. are often combined with grading equipment to form a closed-circuit circulation system, which can achieve higher pulverization efficiency.
(3) Open circuit crushing process with pre-grading.
(4) Closed circuit crushing process with pre-grading.
When the feed contains more qualified materials, pre-classification can separate them to reduce the load on the mill, avoid “over-grinding” of fine materials, and help improve the crushing efficiency.
(5) Open circuit crushing process with final classification.
(6) Open circuit crushing process with pre-grading and final grading.
In terms of crushing and classification methods, it can be divided into two processes: dry method and wet method. The number of crushing and grading stages mainly depends on the particle size of the raw material and the required product particle size.
Selection of process equipment
In practical application, it is necessary to select the appropriate equipment according to the physical and chemical properties of the material, the performance of the ultra-fine grinding equipment, the grinding method (dry method, wet method) and supporting grading equipment, etc., and determine the optimal process parameters through process tests .