The Effect of Chemical Pretreatment on the Desulfurization of Coal by Selective Oil Agglomeration, September 1978

(1978) The Effect of Chemical Pretreatment on the Desulfurization of Coal by Selective Oil Agglomeration, September 1978. Iowa State University

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Abstract

An experimental investigation was carried out to improve selective oil agglomeration as a method for separating coal and mineral particles. The effectiveness of a special method of chemical pretreatment for enhancing the rejection of inorganic sulfur and ash by subsequent agglomeration was studied. The special treatment used hot alkaline solutions containing dissolved oxygen to oxidize pyrite, reducing its tendency to agglomerate with finely divided coal particles. Sodium carbonate was found to be a very effective alkali for use in the pretreatment reaction. There appeared to be an optimum sodium carbonate concentration (1 or 2 wt%) for the rejection of inorganic sulfur by oil agglomeration. By pretreating coal containing 4.96% inorganic sulfur and 15.7% ash with a 2.0 wt% sodium carbonate solution at 80°C for 15 min, 87.9% of the inorganic sulfur and 63.6% of the ash were removed by selective agglomeration with a heavy fuel oil mixture. Chemical pretreatment was found to be more effective in reducing the inorganic sulfur content of minus 400 mesh coal than of minus 100 mesh coal.