Effect of particles micro characteristics destroyed by ball milling on fly ash electrostatic separation

It is meaningful to investigate fly ash triboelectrostatic separation from a microscopic point of view. The ball milling pretreatment was proposed to improve the recycling efficiency (RC) of unburned carbon in fly ash. Particles models were established referring to the microscopic characteristics of particles obtained by scanning electron microscope (SEM). Electrostatic separation of three particles with different microscopic characteristics was analyzed by CFD-DEM coupled calculation. The comparative experiments between pretreated and untreated particles were performed. The feasibility of ball milling pretreatment was evaluated based on the loss on ignition (LOI) and productivity (PR). The results show that microscopic characteristics of particles have a serious impact on separation. Higher voltage is beneficial to the separation, but the flow velocity needs to consider the particles characteristics. It is difficult to realize high-efficiency separation by adjusting flow velocity and voltage. The ball milling treatment can destroy the complex microscopic characteristics of particles and reduce the particle size. As compared with untreated particles, the RC and PR of unburnt carbon for particles treated by ball milling can be increased by 2.19% and 32.38% respectively. The flow velocity of 10 m/s and voltage of 15 kV are suitable operating conditions.(c) 2022 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.

Automated summary

Investigating fly ash triboelectrostatic separation from a microscopic point of view is meaningful. The study proposes ball milling pretreatment to improve the recycling efficiency of unburned carbon in fly ash. The results show that the microscopic characteristics of particles have a significant impact on the separation process, and adjusting voltage and flow velocity can enhance the efficiency of separation.