Thermal phase transition of pyrite from coal

Abstract

The thermal phase transition of pyrite from coal was studied using thermogravimetry and derivative thermogravimetric, infrared spectroscopy and X-ray diffraction (XRD). According to the XRD results, the phase transition of the pyrite starts at 350 °C, pyrrhotite and magnetite are intermediate products of the oxidation from pyrite to hematite. It was proposed that the main gases and volatile products released during the thermal decomposition of the pyrite are water (H2O) and sulfur dioxide (SO2). The existence of sulfate species in the roasted samples also verified the emissions. These results proved the phase transition of pyrite and explain that they have a rational relationship. The environmental impact related to the thermal phase transition has been discussed, although the pyrolyzation in natural environment is really a very complicated process, it is still able to understand the thermal habits of pyrite in coal by studying pyrite from coal and control surrounding conditions so as to reduce and improve the environmental impact of sulfur pollution.