Research on quantitative method of particle segregation based on axial center nearest neighbor index

Abstract

The phenomenon of particle segregation generally occurs during the operation of the ball mill. However, the traditional quantitative index of particle mixing and segregation degree is suitable for overall segregation, which cannot accurately reflect the axial segregation. For the problem of axial segregation of particulate matter in the rotating drum, an axial center nearest neighbor index (ACNN) method is proposed. The method uses the nearest neighbor segregation factor and the center compensation distance to measure the mixing and segregation, and further characterizes the evolution of the particle–particle positional relationship in the particle system, reflecting the degree of spatial and temporal mixing and segregation. The comparison of the experimental and simulation results shows that the ACNN method can accurately quantify the overall segregation degree based on the instantaneous information about the particles in the different shaft sections. By comparing and analyzing the relationship between different shaft segments and the overall segregation degree, the particle mixing and segregation process of the different shaft segments in the rotating drum was studied. The results show that an indicator of the overall degree of segregation cannot be acquired by observing a single shaft section. The effects of particle size ratio and density ratio compete with each other, but promote different segregation pattern of particles respectively. The axial segregation of the drum is characterized by smaller particles gathering towards the middle of the drum, and a large length to diameter ratio (L/D) has a restraining effect on segregation characteristics.