Bacterial leaching of coal for the removal of pyritic S

Abstract

Most commonly used microorganisms are Thiobacillus Ferrooxidans and Thiobacillus Thiooxidans, which have been shown to be effective in the removal of pyritic sulphur from coal. This study presents the results of bacterial leaching of coal for the removal of pyritic sulphur. The coal sample from UK contains 3.70% total sulphur where 2.43% is in pyritic form. Particle size and cyclosizing, Fe content of the leaching solution and time of leaching were the main criteria of the study. Bacterial leaching was applied on samples in flask for days and sized fractions for 24 hours. Results showed that 35% pyritic S could be removed in 24 hours whereas 90% pyritic S removal was achieved after 22 days. However, if the pyrite in coal sample is preconcentrated using a hydrocyclone technique prior to bacterial leaching then over 83% pyritic sulphur removal can be obtained depending on the fractions within 24 hours, except the first fraction.