Desulfurization of Tabas coal using chemical (Meyers, Molten caustic leaching) and biological (bioleaching) methods

From an economic, technological, and environmental perspective, sulfur removal from coal resources has received increased attention in recent years. The present work investigates the ability of chemical (Meyers and Molten caustic leaching (MCL)) and biological methods for the desulfurization of Tabas coal. Accordingly, in the Meyer process, at ۱ M ferric sulfate concentration, during ۹۰ minutes at ۹۰ ° C, ۶۱.۷۸ % of ash and ۸۲% of pyrite, and ۵۱.۳۵% of total sulfur were removed from Tabas coal, respectively. The MCL method was also investigated. Hence, based on the MCL experimental condition of caustic soda /coal ratio of ۲, leaching time of ۶۰ minutes, and constant temperature of ۱۸۰ ° C, ۷۱.۸۲ % of ash, ۸۸% of pyrite sulfur, and ۵۷.۸۵% of total sulfur content were removed from Tabas coal, respectively. Furthermore, biodesulfurization of Tabas coal was conducted using a mixed culture of acidophilic iron- and sulfur-oxidizing mesophilic bacteria. The effect of time, bacterial medium, solid/liquid (S/L) %, and the absence of bacteria were investigated, and based on the results, time was the most significant parameter. Accordingly, ۶۸.۹۸% of ash, ۹۲% of pyrite sulfur, and ۷۲.۴۳% of total sulfur were removed from Tabas coal with ۲۰% v/v bacterial inoculum during ۲۰ days, respectively.