Research On Extracting Gold And Silver From Copper Anode Slime Flotation Tailings

Recovery of noble metals from flotation tailing of copper anode slime was studied in the thesis. Flotation tailing of copper anode slime containing Au86g/t, Ag0.44%was flotation residue from copper anode slime from which Cu, Se had been leached. The main work of the thesis could be summarized as follows:The wet process consisted of chlorination leaching of gold and leaching of silver with sodium sulfite was examined.The effects of the concentration of sodium chlorate, the concentration of chloride ion, the concentration of hydrogen ions, ratio of solid to liquid, and time on leaching efficiency were investigated in gold chlorination leaching experiment. The optimal experimental conditions of chlorination leaching process that the fist leaching rate of gold was85.2%and the cumulative leaching rate of gold was more than94.3%were obtained at flotation tailing of copper anode slime to74μm, leaching temperature90℃, the liquid-solid ratio2:1, leaching tine7h,1mol/L hydrogen ion concentration,18g/L chloride ion concentration, concentration of sodium chlorate30g/L. The method of chemical gold extractant was used to reduction of gold from chloride leaching liquid. The experimental conditions of gold extractant that the concentration of gold in the extraction raffinate was less than0.1mg/L and gold extraction rate was more than99%were obtained at room temperature, the organic phase to water phase1:3, extraction time5min, clarification time5min; oxalic acid solution as back extract reducer was used for reduction of gold in the organic phase, the experimental conditions that the reduction of gold extraction rate was greater than99.5%were obtained at temperature80℃, leaching time2h,0.5%Oxalates solution; from the flotation tailings to sponge gold, gold direct rate of recovery was92.9%.The effects of the concentration of the sodium sulfite and ratio of solid to liquid were investigated in sliver leaching experiment. The optimal experimental conditions of silver leaching process that the rate of silver was61%were obtained at gold leaching slag fine powder to74μm, liquid solid ratio4:1, the sulfite concentration150g/L, pH8, leaching time3h at room temperature. The silver was reduced by adding formaldehyde from silver leaching liquid. The experimental conditions of reduction of silver that the reduction rate of silver was more than99.5%were obtained at pH11,the mole ratio of formaldehyde to Ag1:3; from the flotation tailings of gold leaching slag to sponge silver, silver direct rate of recovery was60.7%.