In-situ high temperature X-ray diffraction study on the phase transition process of polymetallic sulfide ore

The phase transformation of the polymetallic sulfide ore is quite complicated, especially the variety and diversity of the roasted intermediate. The mineralogy properties of the ore particles were characterized by XRF, ICP and SEM-EDS. The thermal stability of the complex ore was investigated using TG-DSC under different atmosphere (pure N₂ and 1% O₂–N₂). The phase changes and intermediates were revealed by the in-situ XRD in pure N₂ and 1% O₂-N₂ atmospheres with the temperature range from 25 to 800°C. These results indicated that the crystal transformation of the pyrrhotite from monoclinic to hexagonal at 320°C, and the pentlandite and chalcopyrite were decomposed into monosulfide solid solution in pure N₂. While the pentlandite and chalcopyrite were completely oxidized into M*_xFe₃-_xO₄ (M*=Fe, Ni, Cu) and Fe₂O₃, which is also the final product of the ore sample oxidized under 1% O₂–N₂ atmosphere.