Biodesulphurization of coal: behaviour of trace elements

The purpose of this study is to show how the different size fractions of coal are affected during a process of biodesulphurization in a packed column and to examine the repercussions of the process on the elimination of certain heavy and trace elements. The total desulphurization obtained in 51 days is about 25 wt%, as only pyritic sulphur is attacked. The greatest reduction in sulphur content was for the 1–0.5 mm fraction although the lowest actual sulphur content was found in particles of under 0.125 mm, where it dropped from 1.76 to 1.17 wt%. The most important changes in the metal content were decreases in Ni, Cu, Zn, As, Cr, Co and Sr, mainly in the smaller sizes.