[The effect of minerals on transformation of sulfur during pyrolysis and partial gasification]

In this study, the effect of acid treatment of Yima coal on predesulfurization during pyrolysis and partial gasification were investigated. The coal was treated with HCl, HCl-HF and HCl-HNO3 solution, in which different minerals were eliminated. The whole process could be divided into pyrolysis and partial gasification. In pyrolysis process, the evolution of H2S and COS show two peaks, which were 450 degrees C and 600 degrees C respectively. At high temperature, the amount of H2S evolution from acid treated coal was markedly increased compared to the raw coal through the elimination of minerals. In the case of HCl-HNO3 treated sample, the H2S evolution in the low temperature region, below 500 degrees C, was reduced and the COS evolution in higher temperature region, above 500 degrees C, was increased by the chemical oxidation. In the partial gasification process, the sulfide sulfur removal of acid treated coal char was increased, reached about 100% at 800 degrees C. The maximum of total and sulfide sulfur removal of parent coal char were 46.39% and 52.97% at 700 degrees C. Compared to acid treated coal char, the effect of alkaline minerals for fixing sulfur was strengthened with increasing the temperature. The organic sulfur of acid treated coal char was released with carbon gasification, and the value could be constant.