Quartz bleaching by oxalic acid: Relationship between rejection rate of impurities and color response

Abstract

Quartz beneficiation has been applied to meet market requirements by physical and/or chemical methods. Chemical beneficiation has long been investigated by inorganic (e.g. sulfuric acid) and organic (e.g. oxalic acid) acids. Oxalic acid bleaching of quartz ore has taken great interest. This work was conducted to investigate the relationship between metal (Fe, Al, Mg) rejection rates and color responses of bleached quartz ore. Bleaching tests were conducted in agitated pulp condition at different oxalic acid concentrations (0.01M, 0.04M, 0.1M and 0.4M) and temperatures (80°C, 90°C and 95°C) for 90 min. Efficiency of process was measured by colorimetric analysis applied on bleached quartz and chemical analysis (ICP-MS) applied on metal loaded leach liquor. Experimental results revealed that mineralogical composition of ore affected the oxalic acid bleaching of quartz ore. Whiteness could considerably be increased, and yellowness was decreased by manipulating the leaching temperature and acid concentration. But, proportional improvement in the redness could not be achieved possible due to presence of insufficiently leached free dark colored particles in addition to the necessity to apply oxidizing potential in strongly acid environment. Copyright © IMCET 2019 International Mining Congress and Exhibition of Turkey. All rights reserved.