ABSTRACT
There is a substantial reserve of tertiary coals in Assam which are of good quality, particularly with regard to a characteristically low ash content, usually combined with a good coking character. Despite this, these coals cannot, in general, be utilized properly, as they contain a high amount of sulfur. Assam coals are unique in having a high organic sulfur content (2 to 6%) but little pyritic sulfur. This chapter aims to remove sulfur from Assam coals by bacterial means under laboratory-controlled conditions. For the purpose of this investigation an iron-oxidizing strain of Thiobacillus. ferrooxidans was used. Total sulfur and the distribution of different forms of sulfur content of the coal samples were estimated according to standard procedures. The coal samples were also treated by the bacteria under different conditions. Eighty-five percent of the pyritic sulfur was removed from acid-treated coal, whereas only 60% of the pyritic sulfur was removed from the original sample that had not been treated with acid.
