Dry triboelectrostatic beneficiation of fly ash

A laboratory-scale triboelectrostatic separation system in conjunction with analytical techniques was used to study fly ash beneficiation. Fly ash samples were characterized by size analysis and carbon content and then subjected to dry triboelectrostatic separation. Due to differences in the surface physical and chemical properties of the carbon and ash, particles of unburnt carbon and fly ash were triboelectrically charged to opposite polarity and then separated by passing them through a static electric field. Ash fractions deposited on the positive and negative electrodes were collected, analysed for carbon content and subjected to SEM and petrographic analyses. The results indicate that the physical and chemical properties of the ash dictate the maximum carbon-ash separation that would be possible. In addition, the potential of dry separation technology for removing unburnt carbon from coal ash was demonstrated.