Abstract:
In the production process of zinc sulfate, the presence of Fe and Mn had an adverse effect on the crystallization process of zinc sulfate production and reduce the purity of MgSO
4·7H
2O. Traditional chemical treatment methods are costly and easy to introduce new impurity ions. To obtain high-quality zinc sulfate, it is essential to develop a new Fe
2+ and Mn
2+ removal process. In this experiment, micro-nano bubble and ozone oxidation combined technology was used to explore the influence of different gas sources, temperature, CaCO
3 dosage method and dosage on the oxidation effect of Fe
2+ and Mn
2+, and to analyze the feasibility of the technology in a practical production application. Results showed that the removal rate of Fe
2+ and Mn
2+ was more than 99.5% with ozone as the gas source, which was much higher than that with air and oxygen as the gas source. The increase of temperature had an effect on the stability of micro and nano bubbles and the solubility of ozone, which was not conducive to the oxidation of Fe
2+ and Mn
2+. The treatment time of Mn
2+ at the maximum temperature of 18℃ was shortened by 12.5% compared with that at 24℃. The addition of CaCO
3 significantly improved the removal efficiency of Fe
2+ and Mn
2+ by micro-nano ozone. When the relative dosage of 0.44 g/L CaCO
3 was added every 15 min, the adequate total amount of CaCO
3 was 17.6 g, and the complete Removal of Fe
2+ and Mn
2+ took about 50 min, which shortened the treatment time by 33% compared with the treatment time without CaCO
3. Effect of intermittent dosing was better than that of one-time dosing, and the amount of CaCO
3 consumed was more petite.