Thermal decomposition kinetics of arsenopyrite in arsenic-bearing refractory gold sulfide concentrates in nitrogen atmosphere

Abstract

The thermal decomposition kinetics of arsenopyrite in arsenic-bearing refractory gold sulfide concentrates in a nitrogen atmosphere was studied, which using TG-DTG method at heating rates of 5, 10, 15, and 20 K/min. The reaction consistes of four steps, of which the second step involves arsenopyrite decomposition. In this study, we focus on the thermal decomposition kinetics of arsenopyrite. The apparent activation energy (E), pre-exponential factor (A), and reaction mechanism model were obtained by employing data comparison of Kissinger-Akahira-Sunose, Flynn-Wall-Ozawa, and Coats-Redfern methods. The kinetics mechanism was verified by scanning electron microscopy-backscattered electron imaging. The thermal decomposition of arsenopyrite was initiated at the surface and extended to the crystal nucleus, with the pyrrhotite in situ forming a porous structure. The reaction model was consistent with ‘Jander’s 3D diffusion equation model’. The equations for the thermodynamic activation parameters and the absolute temperature was established, and the parameter values were calculated at different characteristic temperatures.