Reduction of high-sulphur coal in the potassium-liquid ammonia system

Polish high-sulphur coal was twice subjected to reduction in the potassium- liquid ammonia system. The process was carried out on both raw and deminera lised coal. Elemental and spectral analyses of the initial coal and the red uction products were performed. Different forms of sulphur found in the sam ples were studied by the classical chemical methods and by atmospheric pres sure-temperature programmed reduction (AP-TPR). The effect of reduction on particular sulphur compounds is discussed. It was found that reduction in t he potassium-liquid ammonia system led to cleavage of C-S bonds, appearance of thiol groups, and the partial removal of pyrite and sulphates from the coal whereas the content of elemental sulphur did not change significantly. (C) 1999 Elsevier Science Ltd. All rights reserved.