Study On The Rules For The Changes Of The Structures And The Properties Of Mechanically Activated Sulphide Ores

Mechanical activation can effectively enhance the hydrometallurgical processes for predominant amount of sulphide ores difficult to be leached. Therefore, it is necessary for us to find the general law in order to predict the mechanisms and the effects of mechanical activation of different sulphide ores.The structural changes of non-activated and mechanically activated pyrite, sphalerite, galena and molybdenite were investigated using X-ray diffraction analysis (XRD), particle size analysis, gravimetrical method and X-ray photo-electron spectroscopy (XPS), etc. The results show that the lattice deformation ratios of these sulfide ores increases gradually with the increase of grinding time, lattice deformation ratio for different mechanically activated sulphide ores at the same grinding time decreases in the order of sphalerite > galena > pyrite > molybdenite. The specific granulometric surface areas (SG) of mechanically activated sulphide ores increase gradually with the increase of grinding time, and the specific granulometric surface areas (SG) of mechanically activated pyrite, galena and sphalerite remain constant after a certain grinding time. Mechanically activated sphalerite and molybdenite almost don't contain elemental sulphur, but a larger amount of elemental sulphur appears in mechanically activated pyrite than that in mechanically activated galena. The sensitivity of sulphide ores to oxidative grinding atmosphere decreases in the order of pyrite > galena > sphalerite molybdenite. All these results indicate that the mechanism of mechanical activation for pyrite is mainly determined by the formation of reactive sites on the surface of mecanically activated pyrite; the mechanism of mechanical activation for galena is determined by the formation of reactive sites and lattice deformation on the surface of mecanically activated galena; the mechanisms of mechanical activation for sphalerite and molybdenite are mainly determined by the lattice distortion on the surface of mecanically activated sphalerite and molybdenite, but the lattice deformation ratio of mechanically activated molybdenite is very small.The structural changes of mechanically activated pyrite, galena and sphalerite after being aged under different aging conditions were also investigated for the first time. The results show that XRD patterns ofABSTRACTmechanically activated sulphide ores during being treated at ambient temperature under inert atmosphere are almost overlapped with that of respective mechanically activated sulphide ores without being aged. Only the specific granulometric surface areas (S) of mechanically activated sulphide ores decrease with increasing the aging time, and remain constant after a certain aging period. On the other hand, the sensitivity of mechaically activated sulphide ores during the exposure to ambient air to oxidative aging atmosphere decreases in the order of mechanically activated pyrite > mechanically activated galena > mechanically activated sphalerite, and mechanically activated sphalerite isn't oxidized under this condition. These results intensively indicate that the formation of reactive sites on the surface of mechanically activated pyrite and galena leads to the sensitivity to oxidative aging atmosphere, and lattice deformation on the surface of mechanically activated sulphide ores isn't easy to be relaxed under above aging conditions.Thermal behaviors of non-activated and mechanically activated sulphide ores and the kinetics of thermal decomposition for non-activated and mechanically activated pyrite were studied using thermogravimetry method (TGA) for the first time. Non-activated and mechanically activated sphalerite and molybdenite undergo no thermal decomposition from 25癈 to 1000癈 under inert atmosphere, but the initial decomposition temperature of pyrite and galena under inert atmosphere decrease gradually with increasing the grinding time. And the apparent activation energies of the decomposition for pyrite under inert atmosphere decrease gradually with increasing the grinding time.