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.

中文翻译：

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基于轴心最近邻指数的颗粒偏析定量方法研究

摘要 球磨机运行过程中普遍存在颗粒偏析现象。然而，传统的颗粒混合和偏析度定量指标适用于整体偏析，不能准确反映轴向偏析。针对转鼓内颗粒物轴向分离的问题，提出了一种轴心最近邻指数（ACNN）方法。该方法利用最近邻偏析因子和中心补偿距离来衡量混合偏析，进一步表征粒子系统中粒子-粒子位置关系的演变，反映时空混合偏析的程度。实验与仿真结果的对比表明，ACNN方法可以根据不同轴段中颗粒的瞬时信息准确量化整体偏析程度。通过对比分析不同轴段与整体偏析度的关系，研究了不同轴段在转鼓中的颗粒混合与偏析过程。结果表明，通过观察单个轴截面无法获得整体偏析程度的指标。粒度比和密度比的影响相互竞争，但分别促进了不同的颗粒偏析模式。转鼓轴向偏析的特点是较小的颗粒向转鼓中部聚集，