Useful application of plasma torch furnace to sulfide mineralogy

Abstract

Using a Plasma torch furnace, melting experiments of sulfides such as pyrrhotite, molybdenite, tungstenite and some Cu-Fe-S compounds were carried out. The melting products of these compounds, under extreme high temperatures, show some unusual mineralogical characteristics. Typical examples are (1) the values of d(102) of hexagonal pyrrhotite with a few wt.% of Cu are larger than that of stoichiometric FeS (2.0932A) and 10 months annealing of the products produced an assemblage of mackinawite+troilite, and (2) bornite+pyrrhotite assemblage is always produced by melting the compounds whose composition is between chalcopyrite and cubanite.
Usefulness of the Plasma melting method is stressed in spite of the unavoidable sulfur loss during the melting, uncertainty of the temperature determination and heterogeneity of the melting products.