中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 28 No. 12 December 2018 |
（1. Department of Materials Engineering, Azarbaijan Shahid Madani University, Tabriz, Iran;
2. Materials and Metallurgical Engineering department, University of Zanjan, Zanjan, Iran;
3. Faculty of Materials Engineering, Sahand University of Technology, Tabriz, Iran）
Abstract:The selective precipitation of zinc from zinc-nickel sulfate solution with the Zn/Ni molar ratio of 20:1 was studied. Dropwise addition of 0.5 mol/L NaOH solution into the zinc-nickel sulfate solution containing 0, 0.01, 0.02, 0.03 and 0.04 mol/L ethylene diamine tetraacetate (EDTA) as a chelating agent was done. The equilibrium analysis of precipitation pathway was performed using Visual MINTEQ program. The equilibrium analysis showed that the presence of small amounts of EDTA can prevent nickel precipitation in alkaline conditions without any negative effect on zinc precipitation. On this basis, more than 90% of zinc could be precipitated as a product with about 50% Zn and only 0.11% Ni at pH=9.0 merely as a result of the presence of 0.03 mol/L EDTA in the solution. The stirring time of 120 min after precipitation was found to be essential for more complete separation. The X-ray diffraction studies on the precipitate revealed that the precipitated phase was Zn4(OH)6SO4.4H2O.
Key words: zinc; nickel; hydrolytic precipitation; separation; chelate; equilibrium analysis
