THERMOANALYTICAL STUDY ON THE OXIDATION OF SULFIDE MINERALS AT HIGH TEMPERATURES

摘要

An experimental study on the oxidation of chalcopyrite (CuFeS_2), pyrite (FeS_2), covellite (CuS) and chalcoeite (Cu_2S) particles was conducted by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) techniques. Oxygen concentration in the process gas was set to 40 and 70 percent by vol. and a heating rate of 40 deg C/min was used. Response variables included: the temperature of incipient reaction, the total exothermic heat of reaction, particle mass, morphology, and mineralogy of the reacted particles. Based on the experimental data and phase stability calculations, reaction mechanisms were proposed to represent the behavior of the particles during oxidation. The reaction mechanisms were verified by X-ray diffraction (XRD) analyses of the oxidized particles, and by thermochemical and mass balance calculations to reproduce the DSC and TGA thermograms. Overall kinetic models were developed to represent the evolution of the exothermic heat of reaction for each mineral as a function of time. Experiments conducted with copper concentrate particles containing the minerals studied suggest that the reaction mechanisms for the individual minerals can be used to represent the oxidation behavior of the copper concentrate particles.