Selective electric-oxidation leaching and separation of Dexing molybdenite concentrates

A novel technique of selective electric-oxidation leaching, solvent extraction and ion exchange adsorption was studied for the recovery of Dexing molybdenite concentrates. The results show that the electric-oxidation leaching of molybdenite is impacted evidently by pH value of electrolyte. When the pH of electric-oxidation process was adjusted by buffered solutions of sodium carbonate and ammonium acid carbonate to about 9, MoS2 and ReS2 could be selectively oxidized, the dissolution rates of molybdenite and rhenium are 99.35% and 99.79%, respectively. Compared with that of the unbuffered system, the dissolution rates of molybdenite and rhenium increase by 23.86% and 26.50%, respectively. In the process of selective electric-oxidation leaching, chalcopyrite would not be leached, the grade of copper in the residue is 10.84% with a recovery rate of 97.93%, and it can be used as copper smelting materials. The separation of molybdenum and rhenium in the electrolyte was studied by solvent extraction and D201 resin adsorption. Coextraction of molybdenum and rhenium is found when N235 was used as an extractant and the concentration of HCl was adjusted to 25.48 g/L, the extraction efficiencies of Mo(Ⅵ) and Re(Ⅶ) are 99.84% and 95.19%, respectively. The stripping of molybdenum and rhenium to aqueous phase was investigated using 17% ammonia liquor, the stripping efficiencies of Mo(Ⅵ) and Re(Ⅶ) are about 99.89% and 99.54%, respectively. After stripping, rhenium was separated from molybdenum using D201 resin under pH 8 at 30 ℃, the adsorption rates of rhenium and molybdenum are 92.18%, 3.46%, respectively, and the separating factor is 169.56.