BEHAVIOR OF COAL PYROLYSIS DESULFURIZATION WITH MICROWAVE-ENERGY

The behaviour of coal pyrolysis desulfurization by microwave radiation under a nitrogen flow stream was investigated. The microwave method decreases the volatile matter loss and slightly improves the desulfurization efficiency, as compared with external heating pyrolysis. It was found, by Mossbauer spectroscopic analysis, that the dissociation of pyrite in coal to pyrrhotite and/or troilite, to different degrees, occurred at varying radiation times. The nascent gaseous sulfur compounds evolved from desulfurization were subject to fixation reactions, resulting in less sulfur removal. Sulfur removal dramatically rose after pretreatment with 5% HCl. This is probably due to depression of the fixation reactions. Also, when double exposure was conducted prior to treatment with 5% HCl, sulfur removal was further enhanced.