Complex Sulphide Copper Thermal Activation Pretreatment - Pressure Leaching Studies

The development of pressure-hydrometallurgy technology and the research on the hydrometallurgy of copper sulfide ores was reviewed first in this dissertation. On the basis of the mineralogical analysis, the heat-activation pretreatment-pressure leaching technique of complex copper sulfide concentates was proposed to achieve high leaching efficiency of copper sulfide concentrates with tetrahedrite as the main mineral. The mai subjects in this dissertation are as follows:The kinetics of direct pressure leaching of unpretreated copper concentrate was studied. The results showed that much higher temperatures were propitious to the leaching of copper and iron. The leaching rate of zinc was higher than that of copper when the leaching temperature was lower than 438K. When the leaching temperature was raised at 453K, the leaching rate of copper was superior to that of zinc. The kinetic research also proved that the dierect leaching of unpretreated copper sulfide concentrates was controlled by the interface chemical reaction.The optimized techniques for the heat-activation pretreatment including low-temperature roasting and microwave activation as well as the pressure leaching of activated complex copper sulfide concentrates were respectively studied and further determined by single-factor tests. The technique of low-temperature roasting pretreatment was as follows: the roasting temperature of 573K, the roasting time of 1～2h. The technique of microwave-activation was as follows: the microwave power of 82W, the microwave activation time of 120sec, the batch weight of copper concentrates of 95g. No loss of lead, zinc, sulfur and arsenic contained in the concentrates was occurred and the deleterious smoke containing SO2 was not produced during the heat-activation pretreatment stated above. The pressure leaching technique of activated copper concentrates was shown as follows: the leaching temperature of 453K, the oxygen partial pressure of 0.6 MPa, the initial concentration of sulfuric acid of 1.23mol/L, the liquid to solid ratio of 5/1(mL/g), the calcium lignosulphonate dosage of 1.25% of the weight of the concentrates, the leaching time of 2h, the agitation speed of 500r/min.The extraction of copper and zinc was achieved at 94.08% and 96.95% respectively while that of iron was 22.37% under the conditions of low-temperature roasting pretreatment-pressure leaching technique. The extraction of copper, zinc and iron was achieved at 86.36%, 92.33% and 27.64% respectively under the conditions of microwave activation pretreatment-pressure leaching technique. The leaching residues of microwave-activated copper concentrates may be returned to the rationing of leaching materials for high recovery of copper and zinc after the residues is processed by high-temperature kerosene for the deprivation of elemental sulfur.Comparison between these two techqiues of heat activation pretreatment-pressure leaching was also carried out in this dissertation and the heat-activation mechanism of complex copper sulfide concentrates was further discussed.