关键词: 煤, 摩擦电选, 气力输送, 摩擦荷电, 模型, 参数估值

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