The effects of chemical pretreatment on tribocharging of density fraction coal

• The density fraction coal samples prepared were pretreated by chemicals.
• The effects on tribocharge performance were studied by measuring the charge-to-mass.
• Tribocharge of middle density coal is the worst compared with the lower and higher.
• Light diesel oil, ammonia and kerosene increase the charge of lower density fraction.
• Ethanol and lignin decrease the tribocharge performance of higher density fraction.

Dry triboelectric separation of coal depends on tribocharge difference of the coal and gangue mineral. The coal samples of different density fraction prepared by sink-and-float method were pretreated by chemicals and their effects on the tribocharge performance with stainless steel were studied by measuring the charge-to-mass and relative dielectric constant. The results show the tribocharging performance of middle density fraction coal is the worst compared with other density fractions. The charge of lower density fraction was increased by chemical conditioning with light diesel oil, ammonia, and kerosene, while the charge of higher density fraction was decreased with ethanol and lignin.