Dry separation on coal–silica mixture using rotary triboelectrostatic separator

Silica minerals are one of the major contaminants in coal. They significantly deteriorate the coal quality and need to be removed before the use of coal. Conventional coal preparation techniques are wet processing methods that require huge quantities of water and chemical reagents, which induce high operation cost and environmental pollution. Therefore, dry separation technique to preconcentrate coal before the wet processing or even substitute the wet processing is required. In this study, the coal–silica mixture was beneficiated using a novel rotary triboelectrostatic separator (RTS). This new type of electrostatic separator is characterized with high particle charging efficiency, good separation environment and high throughput. The experiment result shows the surface charge densities of the coal, and the silica particles are greatly enhanced and the ash rejection of coal–silica mixture is achieved using the RTS. The ideal coal–silica mixture electrostatic separation characteristic using the RTS was determined. The charge density difference between coal and silica particles is distinct after the charging process. Better separation efficiency could be obtained when an industrial size RTS is available to use.