Spontaneous combustion tendency of fresh and pre-oxidized sulfide ores

Abstract

Three representative sulfide ore samples were collected from typical metal mines, and their corresponding pre-oxidized products were obtained under nature environment. The thermal behaviors of each sample at heating rates of 5, 10, 15 and 20 °C/min in air flow from ambient temperature to 800 °C were studied by simultaneous thermal analysis and the TG/DSC curves before and after the pre-oxidation were compared. By the peak temperature of DTG curves, the whole reaction process for each sample was divided into different stages, and the apparent activation energies were calculated by the Ozawa-Flynn-Wall method. The results show that the reaction process of each sample after pre-oxidation is more complex, with quicker reaction rates, fewer heat production quantities, and higher or lower ignition-points. The apparent activation energies decrease from 364.017–474.228 kJ/mol to 244.523–333.161 kJ/mol. Therefore, sulfide ores are more susceptible to spontaneous combustion after the pre-oxidation.