Semi-continuous bioleaching of heavy metals and trace elements from coal

The micro-organisms used in the processes of sulphur elimination from coal by bioleaching are currently considered to play an important part in the di ssolving of other elements (Cu, V, Ni, Pb, Cr, Se, As, etc.). In this study an analysis is carried out a process of biodesulphurization of coal and th e elimination of certain heavy and trace elements. An 8.4-litre reactor was used, comprising three columns connected in series with a volume of 2.8 li tres each. Twenty elements were studied, in three groups according to the criteria of the National Research Council of the USA, major components found in most co als in large quantities, elements harmful to the environment and elements o f medium and low environmental impact. Of the major components, only iron, calcium and phosphorous are leached throughout the process. Of the harmful elements, it can be said that almost all the cadmiun released is due to bio leaching. Arsenic and boron are also bioleached in the process. Of the elem ents of medium and low environmental impact, it is our opinion that only co pper is dissolved, at least to any great extent, by bioleaching.