Depression mechanism of sulfite ions on sphalerite and Pb2+ activated sphalerite in the flotation separation of galena from sphalerite

Researchers have focused more on the depression mechanism of sulfite ions on copper activated sphalerite. The depression mechanism of sulfite ions on sphalerite and Pb2+ activated sphalerite in the flotation separation of galena from sphalerite still lacked in-depth understanding. Therefore, the depression mechanism of sulfite ions on sphalerite and Pb2+ activated sphalerite in the flotation separation of galena from sphalerite was further investigated by experiments and DFT calculations. Firstly, sulfite ions and oxygen were more likely to co-decompose xanthate treated by Zn2+ than xanthate treated by Pb2+, suggesting that the xanthate adsorbed on the surface of sphalerite was unstable. Secondly, sulfite ions were chelated with lead ions in solution to form PbSO3 and the hydrophilic PbSO3 was more easily adsorbed on sphalerite than galena. Thirdly, sphalerite was further inhibited by the product OH− in the oxidation process of sulfite ions, and OH− was more easily adsorbed on the surface of sphalerite in comparison with galena. However, sulfite ions hardly inhibited the flotation of galena and could promote the flotation of galena to some extent. Ultimately, sulfite ions could successfully achieve flotation separation of galena from sphalerite.