Technology Research On Cyanide Removal Of Iron Concentrate By Magnetic Separation From Cyanide Tailing

Abstract:In the case of hydrometallurgy of gold, most of the gold corporations adopt cyanide gold leaching process. Every year, a great number of cyanidation residues were generated, which result in potential pollution to environment and water resource and problems of recycling the valuable metals in the residues. Removing cyanogen from gold cyanidation residues and the associated resources for free-pollution plays an important role in environmental protection and comprehensive utilization of resources.Iron concentrate containing cyanogen obtained by magnetic separation of cyanidation residues was chosen as research object, and experimental results demonstrate that iron concentrate contains easy-release cyanide and metal complex cyanide, and the content is35mg and28mg, respectively. Disposal of easy-release cyanide and metal complex cyanide was conducted by oxidation (SO2and O2) and precipitate flotation union technology, and it is demonstrated that effective removal of cyanide is obtained, which provides new technological insights for free-pollution treatment of cyanidation residues and the associated resources.Three chemical oxidation methods, namely alkaline chlorine oxidation, hydrogen peroxide oxidation and sulfur dioxide-air oxidation, were developed for removing cyanogens. The best result was obtained by sulfur dioxide-air oxidation, at pH10,10times theoretical oxidant dosage, Cu2+concentration200mg/L and reaction time1h, but the cyanide removal rate was only approximately50%since the metal complex cyanide in iron concentrate failed to be oxidized and decomposed.Precipitate flotation and ion floatation were conducted for disposal of ferrous cyanide ion, and precipitate flotation showed better results. Precipitate flotation of limonite and magnetite was systematically investigated in terms of types and dosage of surfactants and regulators, and experimental results showed the cyanide removal rate of limonite was67.63%under optimal conditions of pH8, dosage of starch1200mg/kg and dosage of RA-715280mg/kg; the cyanide removal rate of magnetite was65.40%under optimal conditions of pH8, dosage of starch1700mg/kg and dosage of RA-715220mg/kg.On the basis of the above experiment, cyanides in the limonite and magnetite are disposed by the joint process of sulfur dioxide air oxidation-precipitation flotation. Then for the processed tailings, the toxicity leaching experiment is performed, and the result is that the total concentration of cyanides in lixiviums of the limonite and magnetite are0.067and0.04mg/L, respectively. And the concentration of cyanides is lower than maximum allowable concentration of surface water requirements.