Compared to coarse-grained powders, the characteristics of ultrafine powders are significantly different due to the material particle size reaching the micrometer level during the ultrafine crushing process: first, the specific surface area and surface energy of micrometer level products are very large, so during the crushing process, the interaction between particles is greatly increased, and tendencies of mutual adsorption and aggregation are increased. To some extent, particles are in a reversible dynamic process of crushing and aggregation. When, at a certain time, the reducing speed of the particle size of the powders is balanced with the speed of aggregation, this is called a crushing balance. Second, as the mineral particle size decreases, the crystal defects in the mineral also decrease, and the strength to resist external forces relatively increases. Therefore, during the ultrafine grinding process, it is generally necessary to configure fine grading equipment simultaneously to grade the qualified powders in a timely manner and avoid re-aggregation of the ultrafine powders. According to the different grading media, the ultrafine classifier can be divided into two categories: the dry classifier with air as the medium and the wet classifier with water as the medium.