Abstract: Triboelectrification system should be designed based on the understanding of triboelectrification characteristics of coal and its associated minerals. Making minerals fully charged of different polarities is the key to strengthening triboelectrification process and enhancing separation efficiency. Pneumatic triboelectrostatic experiments were performed in a copper pipe, and a Faraday cup connected with an electrometer was used to measure the charge-to-mass ratios of particles at the pipe outlet. The effects of air velocity, solid feed rate and pipe length on the specific charge of quartz, kaolinite and calcite were investigated. Quartz, kaolinite and calcite were negative charged when rubbing against the copper pipe. The specific charge of each associated mineral increased with increasing air velocity and pipe length, but decreased with increasing solid feed rate. Under the same experimental condition, calcite acquired the largest specific charge, while quartz got the smallest, and kaolinite got the second place. The work function in order was calcite>kaolinite>quartz>Cu. Based on these results, a triboelectrification model of associated mineral particles during dilute phase pneumatic conveying in the pipe was developed. The correlation coefficient calculated from predicted results and experimental data were all larger than 0.95, and the average relative errors (ARE) were all less than 10%, which indicated that the model could accurately predict the specific charge of associated minerals during dilute phase pneumatic conveying. Therefore, the model can provide guidance for triboelectrification system design.

Key words: coal, triboelectrostatic beneficiation, pneumatic conveying, triboelectrification, model, parameter estimation

摘要： 根据煤粉中煤和伴生矿物的摩擦荷电特性来设计摩擦荷电系统，使煤和伴生矿物充分异性荷电，是强化煤粉摩擦荷电过程、提高分选效率的关键。以石英、高岭土、方解石这3种煤粉中的主要伴生矿物作为研究对象，利用铜管中气力输送过程使颗粒摩擦荷电，并使用法拉第筒和静电计测量铜管出口颗粒的荷电量，研究了气速、给料速度、管道长度对其摩擦荷电特性的影响。结果表明，石英、高岭土、方解石与铜管摩擦均带负电；各伴生矿物的荷质比均随气速增大而增大，随给料速度增大而减小，随管道长度增加而增加；相同实验条件下，方解石与铜管摩擦后荷质比最大，高岭土荷质比次之，石英荷质比最小，功函数大小为方解石>高岭土>石英>铜。基于连续碰撞荷电机理，同时考虑气速、给料速度、管道长度的影响，建立了稀相气力输送过程颗粒摩擦荷电模型。3种伴生矿物颗粒荷质比的模型计算值与实验值的相关系数均大于0.95，平均相对偏差均小于10%。实验结果表明模型具有较高的预测精度，可以为摩擦荷电系统的设计提供指导。

关键词: 煤, 摩擦电选, 气力输送, 摩擦荷电, 模型, 参数估值