The Study On Kinetics And Mechanisms Of Chalcopyrite Leaching

As one of the most abundant copper resources,chalcopyrite tends to be lower in grade due to the excessive mining in recent years.Traditional pyrometallurgical process will produce a lot of SO₂ and other harmful waste dust in the roasting process,causing serious pollution to the environment.In addition,it achieves little effect dealing with low grade chalcopyrite.Hydrometallurgical processes dominate in many aspects,but due to lattice energy and natural poor solubility of chalcopyrite,and the passivation layer formed in the leaching,it has not been widely applied in industry.Therefore,it's imperative to explore the leaching mechanism and to propose a scientific and effective leaching process.In this paper,the influencing factors for chalcopyrite leaching were explored.The optimum conditions are as follows:mineral particle size-75+38?m,pulp pH=1.0,pulp concentration 10 g/L.The effects of impurity ions and their concentrations on the leaching of chalcopyrite were investigated.It was found that NaCl improved chalcopyriteleaching,but Na⁺and K⁺sulfate did not increase chalcopyrite leaching,indicating that Cl^-is favorable to chalcopyrite leaching.In addition,Al³⁺was found to increase chalcopyrite leaching although it is not so evident in the presence of NaCl.In contrast,Mg²⁺ions inhibited chalcopyrite leaching.It was found that chalcopyrite leaching was enhanced when temperature was increased.The activation energy of the leaching reaction was more than 20 KJ/mol,indicating that the reaction was mainly controlled by the interfacial chemical reaction.Furthermore,the addition of NaCl and KCl increased the solution Eh,as compared to the addition of Na₂SO₄ and K₂SO₄ into the leaching system,indicating that the increase of Eh was beneficial to chalcopyrite leaching.X-ray diffraction?XRD?and Scanning electron microscopy?SEM?were carried out to characterize the leached chalcopyrite.The kinetic model was also used to simulate the data.It was found that when NaCl concentration was lower than 0.5mol/L,the leaching rate was low.The main component of the passivation layer was copper polysulfide,following a diffusion model;when NaCl was 0.5 or 1.0 mol/L,the leaching rate was higher.The composition however was elemental sulfur,and the leaching was more in line with the interfacial chemical reaction model.In addition,the leaching rate at 0.5 mol/L Na₂SO₄ and 0.5 mol/L K₂SO₄ was low,and the main component of the passivation layer was found as copper polysulfide.The reaction was more consistent with the diffusion model.