China Nonferrous Metallurgy

To tackle the difficulty in the leaching of refractory Cu-Co alloy, the process of a primary direct acid leaching + a secondary oxidizing acid leaching is adopted for single-factor test, and the influence of each factor on the leaching rate of Co, Cu and Fe is studied. The test results show that the optimal process conditions of the primary leaching are a sulfuric acid concentration being 2mol/L, a reaction temperature at 85℃, an agitation speed of 200r/min, a liquid-solid ratio of 1∶10g/mL and a reaction time of 105min; the optimal process conditions of the secondary leaching are a reaction temperature at 85℃, an agitation speed of 200r/min, a liquid-solid ratio of 1∶10g/mL, sodium chlorate being used as oxidizing agent at a dosage of 30% and the initial acid concentration being 3mol/L, and reaction time lasting 4h. Under such conditions, the relatively high leaching rate of Co, Cu and Fe can be obtained, which are respectively as 95.47%, 96.62% and 96.01%. A unreacted core model is used to characterize the excellent imitative effect of the two-stage Cu-Co alloy leaching process, internal diffusion is the restriction factor of the reaction, the apparent activation energy during the leaching process is within the distribution range of 5~20kJ/mol. In the secondary leaching, the activation energy of Co and Cu is increased by 1.721kJ/mol and 8.888kJ/mol respectively while that of Fe is decreased by 10.186kJ/mol.