Electrostatic Beneficiation of Coal Using a Cyclone-Tribocharger

A preliminary study is presented on a new method of separation of mineral inclusion from coal. The separation process involves triboelectrical charging of pulverized coal by a cyclone-tribocharger and electrostatic differential deflection of the coal. The separation tests for a pulverized Australian coal with 18.5 percent ash content using this separator yielded the following results: a cyclone with a copper wall gives the best separation performance; the percentage ash contents of particles collected on the anode and cathode of the separator are 26 percent and 11 percent, respectively; a coarse pulverized coal with 74-150 pm diameters showed a beneficiation rate better than that for a fine pulverized coal with diameters below 44 pim. In order to understand these results, the authors experimentally examined charging behavior of pure mineral particles fed to the cyclone-tribocharger with either copper or teflon walls and to a fluidization-charger. Avoidance of particle-to- particle collision and choice of cyclone wall material are important in raising the separation performance. On the basis of microscopic observation, the authors confirmed liberation of most mineral inclusion from coal crashed to particles of less than 70-μm diameters.