THERMODYNAMICS OF INTERCHANGE OF CHROMATE IONS WITH MINERAL COMPLEX OF POLYMETAL ORES. CHALCOPYRITE

Abstract

The article presents the results of thermodynamic calculations and analysis of the CuFeS2–H2O–O2–CO2–C4H9OCSS–– CrO42–system characterizing chalcopyrite surface condition under the conditions of selective floatation of copper-lead concentrates according to potassium dichromate technics in alkaline medium. Electrolytic potentials of chalcopyrite are measured experimentally in the solutions of potassium bichromate and potassium butyl xanthate of alkaline pH. As a result of the investigations, the mechanism of formation of sorption collecting agent layer under the conditions of galena depression by chromates-ions is considered. It is sown theoretically that sulfide sulfur oxidation degree should not affect the process of competitive reactions of butyl xanthate formation over chalcopyrite surfaces. It is established from the results of chalcopyrite electrode potential measurement that chromates-ions in a wide range of their concentrations are not potential-determining ones for chalcopyrite. Its surface in alkali solutions of butyl xanthate and potassium bichromate should mainly be hydrophobizated at the expense of copper butyl xanthate formation, and a sorption collecting agent layer of mixed composition as copper (I) butyl xanthate and dixantogen can be formed only in a narrow range of redox potential and pH.