Mechanochemical milling-induced reactions between gases and sulfide minerals I.: Reactions of SO2 with arsenopyrite, pyrrhotite and pyrite

The mechanochemical milling of arsenopyrite, pyrite and pyrrhotite in the presence of SO2 has demonstrated the potential for inducing gas/solid reactions at low temperature. Both reactants and milled products were characterised by powder X-ray diffractometry and by scanning electron microscopy of polished sections. The gas compositions were determined by mass spectrometry. Milling in an atmosphere of SO2 results in the conversion of arsenopyrite to pyrite via an intermediate pyrrhotite phase. Milling pyrite or pyrrhotite results in a continuous cyclic process where pyrite decomposes to pyrrhotite, which then undergoes resulfurisation back to pyrite. (C) 2000 Elsevier Science S.A. All rights reserved.