Synergist enhancement of effective desilication of graphite ore by rotary triboelectric separation and surface modification

Desilication of graphite ores helps to ensure their high-value applications. Surface modification and triboelectric separation methods were used to improve the desilication of graphite ore. Effects of friction media and chemicals on the charge properties of graphite and quartz were investigated by charge-to-mass ratio tests and the adsorption mechanism was analyzed. Furthermore, effects of electrode voltage and rotational speed on the desilication of graphite ore were investigated. The results showed that polyvinyl chloride was the best friction medium for graphite and quartz, and the charging effect of kerosene-modified graphite and quartz was better than that of ethanol. Kerosene modification made graphite more positively charged and quartz more negatively charged, enlarging the charge-to-mass ratio gap. Desilication efficiencies of 0.25–0.5 mm, 0.125–0.25 mm, and 0.074–0.125 mm graphite ores after kerosene modification were 42.27% (20.20% increase), 48.92% (17.18% increase), and 57.26% (19.92% increase), respectively. Our study provides guidance for the purification of graphite.