Industrial symbiosis: high purity recovery of metals from Waelz sintering waste by aqueous SO2 solution

Research on the oxidation characteristics of zinc sulfite in the zinc oxide desulfurization process

Aiming at the pollution problem of low-content SO₂ in non-ferrous metal production industry, the oxidation kinetics of zinc sulfite in the zinc oxide desulfurization process was studied. The concentration change of Zn²⁺, variation of pH, temperature and apparent activation energy in the oxidation process of two ZnSO₃ samples were investigated systematically. The results indicate that the raw material with different crystal water has little effect on the oxidation kinetic of zinc sulfite. The reaction process comprises two stages: the dissolution process and the oxidation process. The zinc ion concentration is linearly rising with the action time during the oxidation process. The pH value rises quickly in the dissolution process and goes down slowly with reaction time in the oxidation process. The process is mainly controlled by a diffusion step and less effected by the temperature. The apparent activation energy E_a obtained for the two samples are 8.662 and 9.645 kJ/mol, respectively. Integrated with the kinetic model, the oxidation rate of zinc sulfite is controlled by the diffusion of HSO₃^- and O₂ to the gas-liquid interface.