Tang Dan Copper Oxide Tailings Leaching

With depletion of the high content ores near-surface layer, resources has become essential issue of sustainable development strategies in China. Therefore, recovering copper from copper oxide,complex ores and low grade ores is more significance by leaching technology. The aim of this work is developing a new method to leach copper oxide ores and to utilize low-grade copper ores efficiently. In this paper, the leaching behaveiors of the tailings of refractory copper oxide ore from Tangdan in Yunnan Province in various solutions have been studied.The conditions of conventional leaching of tailings in ammonia-ammonium solutions have been investigated. The effects of dosage of oxidant, time, total ammonia concentration, [NH4]+/NH3,temperature,solid liquid ratio, oxidant feeding method and oxidation time on copper extraction have been also studied,to get the optimum condition.The results shows that the leaching process of copper ores is controlled by diffusion step.The leaching time, temperature, solid liquid ratio have significant effects on copper extraction. H2O2 is adopted as oxidant and the concentration is 0.0112mol/L.In NH3·H2O-(NH4)2CO3 system,the optimum leaching conditions are 40℃,liquid solid ratio 10/1, add H2O2(0.30mL/g),then adding to (NH4)2CO3 and NH3·H2O after 2 hours,c(NH4+)=3.2mol/L, c(NH3)=0.8 mol/L, reacting another 4 hours. The copper extraction is 69.3%. In NH3·H2O-NH4Cl system, the optimum leaching conditions are 50℃, liquid solid ratio 10/1, add H2O2(0.20mL/g), then adding to NH4C1 and NH3·H2O after 2 hours, c(NH4+)=2.25mol/L, c(NH3)=0.75mol/L, reacting another 4 hours. The copper extraction is 70.6%. In NH3·H2O-(NH4)2SO4 system the optimum leaching conditions are 50℃, liquid solid ratio 10/1, add H2O2(0.20mL/g), then adding to (NH4)2SO4 and NH3·H2O, c(NH4+)= 1.33mol/L, c(NH3)=0.67mol/L, reacting another 4 hours. The copper extraction is 59.2%.The phase analysis of residue of leaching tailing ore shows that the secondary copper sulphide ore is oxidized sufficiently by adding H2O2, but the primary copper sulphide ore almost remains unchanged.Compared with conventional leaching, while that from the secondary copper sulphide ore was raised 2～5 times, which is the basic reason of relatively high copper extraction on the effect of oxidant.