Leaching of copper(I) sulfide in calcium chloride solution

Abstract

Finely grained samples of copper(I) sulphide were leached by CaCl2·2H2O solution with added HCl and the introduction of gaseous oxygen. The occurrence probability of chemical reactions was analyzed based on literature and products, which were formed during the process, and the overall leaching reaction was defined. The effect of temperature, concentration of CaCl2·2H2O, HCl and total chloride ions, stirring speed, phase ratio and time, on the leaching degree of copper was studied. The quantity of copper dissolved increases with the increase of the values of all the parameters. The role of chloride ions is to disrupt the passivating sulphur layer on the particle surface, by promoting the formation of crystalline sulphur rather than a crypto-crystalline or amorphous product. It was concluded that the leaching reaction is second order, with respect to the concentration of total chloride ions. Experimental results show that the leaching mechanism is very complex. By using appropriate mathematical kinetic models, it is found that the leaching rate is diffusion-controlled.