A Novel Process for Treating with Low Grade Zinc Oxide Ores in Hydrometallurgy

A novel, hydrometallurgical process for treating with low grade zinc oxide ores was proposed in this paper. It contains three steps of treatment. Firstly, leaching of ores in alkalescent Ida2−-H₂O system (iminodiacetate aqueous solution). Valuable metals such as Zn, Cu, Ni, Pb and Cd in ores will be dissolved in leaching liquor for their complexation with Ida2−, impurities such as Ca, Mg, Si and Fe will not be dissolved. Secondly, precipitation of Zn from leaching liquor by adjusting basicity with CaO. Zn will be precipitated as ZnO in residues for recovery. Thirdly, precipitation of Ca by adjusting acidity with CO₂ in the solution after Zn precipitation. Ca which was accumulated in the second step will be removed as CaCO₃ from the solution. The lixiviant will be reclaimed in the solution after Ca precipitation. The reclaimed lixiviant solution can be used for re-leaching of ores. The lixiviant solution had been regenerated for 5 times in the paper. The results showed that the performance of the regenerated lixiviant solution could be compared with the freshly prepared lixiviant solution.