Decomposition of Pyrite in a Coal Matrix during the Pyrolysis of Coal

The high levels of sulphur present in Nova Scotian coals may restrict their future use in power generation. A number of beneficiation strategies, aimed at reducing the sulphur levels, are currently under investigation in the Atlantic region; among these is pyrolysis. This work provides a better understanding of the fate of pyritic sulphur from the pyrite/pyrrhotite conversion during pyrolysis. Coal from collieries in Nova Scotia were pyrolysed under argon in a tube furnace at a variety of temperatures and times. Elements of interest in the resultant char were analysed using a scanning electron microscope, equipped with energy and wavelength dispersive spectrometers. The results indicate that sulphur originating from pyrite is transferred to the nearby surrounding organic matrix during the pyrolysis process. This sulphur is in a form which may be very difficult to remove. The possibility of using magnetic separation to reduce the sulphur levels in the char was explored.