Leaching of copper mine tailings from Tangdan

The leaching behaviors of the tailings of refractory copper oxide ore from Tangdan in Yunnan Province in various solutions were studied. The conditions of conventional leaching of tailings in ammonia-ammonium solutions were investigated. The effects of dosage of oxidant, time, total ammonia concentration, concentration ratio of NH4+ to NH3, temperature, solid liquid ratio, oxidant feeding method and oxidation time on copper extraction were also studied, the optimum condition was gotten. H2O2 was adopted as oxidant and the concentration was 11.2 mmol/L. The results show that in NH3·H2O- (NH4)2CO3 system, the optimum leaching conditions are as follows: the temperature is 40°C, liquid solid ratio is 10/1, add H2O2content is 0.30 mL/g, then adding to (NH4)2CO3 and NH3·H2O after 2 h, c(NH4+)=3.2 mol/L, c(NH3)=0.8 mol/L, reacting another 4 h, the copper extraction is 69.3%. In NH3·H2O-NH4Cl system, the temperature is 50°C, liquid solid ratio is 10/1, add H2O2 content is 0.20 mL/g, then adding to NH4Cl and NH3·H2O after 2 h, c(NH4+)=2.25 mol/L, c(NH3)=0.75 mol/L, reacting another 6 h, the copper extraction is 70.6%.