Mechanochemical reaction between sulfur and ilmenite

An ilmenite (FeTiO3) concentrate has been milled with sulfur in a laboratory-scale ball mill for 100 h under a variety of conditions. X-Ray diffraction and thermal processing have shown that reaction occurs within the mill forming pyrite (FeS2) and rutile (TiO2). The reaction was of greatest extent in a mill run under 400 kPa of inert gas; some reaction occurred in a mill under 10(-2) Pa, whereas little reaction was observed when either water or air was present. Annealing of the product powders showed that reaction to TiO2 and FeS2 could be achieved in a closed system after 1 h at 400 degrees C but with the evolution of SO2, whereas annealing at 800 degrees C also gave TiO2 and FeS2, but without formation of SO2 which was thought to have disproportionated to form iron sulfate(VI). Closed-tube annealing of unmilled sulfur and milled ilmenite showed the same reactions as milled powders but of much greater extent.