Coal Cleaning to Remove Trace Elements – A Review

The potential of coal cleaning as a means of reducing the trace element content of coals is reviewed. ‘Conventional’ cleaning can remove significant amounts of trace elements some of which are removed as a simple function of ash reduction. The removal of other elements can be influenced by the equipment used or by more complex interactions between the equipment type and the mode of occurrence of the element. The effect of individual cleaning processes is discussed. ‘Advanced’ cleaning may offer better trace element removal than conventional cleaning; selective agglomeration has been the method studied most. Mild pyrolysis and chemical cleaning are also briefly noted. The final section of the paper concerns the prediction of removal efficiencies. While there is a general relationship between overall ash and trace element removal, there is a need for a greater understanding of the interrelationships between ash and trace elements.