Use of X-ray computed tomography to examine microbial desulfurization of lump coal

The bacterial removal of pyritic sulfur from in situ deposits of coal deserves attention. The process has the advantages of economy and extended periods of time to carry out the sulfur removal. For example, some projected coal reserves are not expected to be mined for another 25-50 years. Possibly a culture and appropriate medium could be admitted to the seam and be allowed to slowly permeate the coal for sufficient time that significant desulfurization occurs. A fair assessment of the in situ desulfurization kinetics and efficiency has not been made for wont of an adequate assay. Therefore, as a preliminary step to examine the feasibility of in situ pyrite removal we have investigated the bacterial removal of the pyrite from lump coal by using X-ray computed tomography to follow the dissolution of pyrite inclusions. It is concluded that X-ray computed tomography is an effective tool to assay in situ phenomena. In particular, mixed cultures of Thiobacillus ferrooxidans and associated acidophilic bacteria were used to treat a Lower Kittanning seam high-volatile A bituminous coal. It was demonstrated that pyrite inclusions can be removed at a depth of 17 mm within the lump over a 4-month period.