Leaching and Kinetic Study of Chalcopyrite Without Acid in an O2–H2O System

This paper studied chalcopyrite’s leaching behavior and kinetics under pressure oxidation conditions in water. The results show that it is possible to efficiently dissolve copper from chalcopyrite only by water, i.e., without any oxidant, and the copper leaching rate reaches 96.4% under the optimal conditions of a temperature of 180 °C, a total pressure of 1.5 MPa, a stirring speed of 900 rpm, and a leaching time of 90 min. XRD and SEM analysis shows that chalcopyrite might not dissolve as Cu 2+ into the liquid phase directly but first transformed into sulfide such as CuS and FeS 2 , which is easier to leach. Then, the newly formed FeS 2 act as a sulfuric acid source to promote the subsequent copper leaching. The kinetics is analyzed using the shrinking core model, and the results show that the surface chemical reaction mainly controls the chalcopyrite leaching process. The apparent activation energy of the chalcopyrite leaching is 62.34 kJ/mol, and the reaction order concerning temperature is approximately 18.0. Graphical Abstract