Optimization and Kinetics of Chalcopyrite Leaching in the Presence of Hydrochloric and Nitric Acids, along with a Particle Shape-Based Evaluation

Abstract The extraction of Cu from chalcopyrite (CuFeS 2 ) by hydrometallurgical methods is becoming increasingly widespread in the world, and hydrochloride (HCl) and nitric acids (HNO 3 ) are important lixiviants used for this purpose. However, chalcopyrite is the most refractory Cu mineral for hydrometallurgical techniques, and therefore determining the appropriate leaching conditions has a crucial role in its beneficiation efficiency. Thus, in this study, the optimum conditions for the chalcopyrite leaching with HCl and HNO 3 acids were determined , and 95% and 96% dissolution efficiencies (DEs) were obtained in the presence of HCl and HNO 3 , respectively, in the optimum conditions. Furthermore, the results of the kinetic model for the control of the general reaction rate indicated that the dissolution of Cu minerals by both acids was diffusion-controlled, with average correlation coefficient values of 0.9955 and 0.9956 for HCl and HNO 3 , respectively. In addition, a particle shape-based evaluation was performed for the leaching feed and residues for the shape factors of circularity, roundness, and solidity to reveal the effect of the leaching processes on the morphology of the particles. The results indicated that the particles approached a circular pattern after the leaching in the presence of both acids. In addition, while more round-edged and less concave particles were obtained after HCl leaching, the edge of the particles became more angular and more concave after the leaching with HNO 3 . The results of this study also showed that optimum leaching conditions were achieved at 63 × 75 µm particle size, 15% solids ratio, 120 min leaching time, and 250 rpm stirring speed, and that the morphological properties of the particles formed as a result of leaching varied according to the lixiviant concentration, ambient temperature, and acid type. It can be seen from the results that the reaction fits the diffusion-controlled model.