Chemical surface modifications of sulphide minerals after comminution

The superficial chemical heterogeneity of sulphide minerals can be natural or induced. Comminution is one possible way for changing, sometimes drastic ally, the surface state of sulphides, which, consequently, modifies the rea ctivity of the divided solid. Using different investigation techniques at t he molecular scale, the chemical nature of the surface of galena, pyrite, c halcopyrite and sphalerite after various comminution conditions can be prec isely described. Galena and pyrite are partially covered with piles of oxid ized sulphates and carbonates species. Elemental sulfur was also revealed i n variable amounts. After wet grinding, the chalcopyrite surface is altered by the formation of a continuous 200-nm-thick layer iron oxy-hydroxides. X anthate molecules can be used as molecular probes for describing the surfac e of ZnS after wet grinding.