Thermal Behavior of Pyrite in the CO2 and N-2 Atmosphere for Obtaining Pyrrhotite: A Magnetic Material

In the southern of Brazil the coal is composed of a large amount of pyrite (FeS2), an environmental problem for this region because the pyrite turns a waste. This work investigated the behavior of pyrite in CO2 and N-2 atmospheres, aiming to identify better thermal treatment conditions of the pyrite waste that favor obtaining a material with magnetic properties. The results show that the samples treated in both conditions presented hysteresis and some magnetic properties. The best results were obtained from N-2 because it is an inert gas, avoiding the pyrite oxidation and, consequently, favoring a major amount of pyrrhotite. The X-ray diffraction analyses showed that partial thermal decomposition of the pyrite occurs at 600 degrees C. The total decomposition was reached at 800 degrees C and the pyrrhotite phase was obtained. Such findings are relative new and can help enhance the utilization of pyrite, contributing to the environmental sustainability of the coal mining industry.