Extraction of ZnO and SiO2 from digestion liquor of high silica zinc oxide ore roasted with alkali by stepwise carbonation and acid leaching processes

The digested liquor of high-silicon zinc oxide ores, which is processed by alkali roasting method, is a mixed solution of NaOH, Na₂ZnO₂, Na₂PbO₂ and Na₂SiO₂. The liquor can be separated by stepwise carbonation, ZnO and SiO₂ can be prepared by acid leaching. The product of the first step of carbonation is Fe₂O₃, which can be used as Iron concentrate. In the second step, ZnO, SiO₂ and PbO are precipitates out, we can get ZnO with further sulfuric acid leaching, and get SiO₂ by chlorhydric acid leaching from the filter residue. There will be only Na₂CO₂ left in the liquor, which can be recycled after causticization processed by CaO.