MECHANOCHEMICAL PROCESSING OF REFRACTORY PYRITE

Mechanochemical reactions are those which are initiated by the applica tion of a mechanical force, In recent times it has been shown that sol id state mechanochemical reactions can be initiated by milling the rea ctants in a high energy ball mill - a process known as mechanical mill ing. Oxidation/reduction reactions have been shown to occur at room te mperature during mechanical milling, and this has led to the idea that it may be possible to refine metallic ores via room temperature mecha nochemical processes, In this study, it has been found that pyrite (Fe S2) can be mechanochemically processed in a high energy ball mill. Pyr ite is the most common sulfide host for gold and in refractory pyrite samples gold is encapsulated in the pyrite matrix, so this matrix must be broken down prior to cyanidation. X-ray diffraction, Mossbauer spe ctroscopy and thermal analysis techniques have shown that pyrite can b e oxidised mechanochemically, with the sulfur retained as a sulfate wi thout the production of sulfur dioxide gas, Potential exists for this process to form the basis for an economically viable, environmentally friendly process for the treatment of refractory pyritic gold ores. (C ) 1997 Elsevier Science Ltd.