Mechanochemical milling-induced reactions between gases and sulfide minerals: II. Reactions of CO2 with arsenopyrite, pyrrhotite and pyrite

X-ray diffractometry, scanning electron microscopy and mass spectrometry ha ve been utilised to study mechanochemical milling of arsenopyrite. pyrite a nd pyrrhotite, separately, in the presence CO2 gas. Arsenopyrite alters to the iron arsenide phase, westerveldite, through an intermediate arsenopyrit e-type phase and pyrite decomposes to pyrrhotite, which appears to be stabl e in CO2, although it does undergo a phase transformation to the hexagonal form. (C) 2001 Elsevier Science B.V. All rights reserved.