| The copper and cadmium slags, composed by copper, zinc, cadmium and other metal elements, mainly come from zinc smelting industry. There are large amounts of metal elements which can cause environmental pollution and waste of resources in slags. According to the properties of elements, an effective separattion process as "leaching-replacement-impurities-extraction-stripping" is proposed and studied in this paper. The results are shown as follows:Sulfuric acid is used as leaching reagent to recover the metal elements by means of two-stage leaching. The two-stage leaching process can ensure the high leaching yield of metals and production of the neutral leaching solution in the exited stream. This technology could provide convenience for the following separation of copper and zinc. When the dosage of sulfuric acid is 1.1 times to the theoretical value, the leaching yield of copper,zinc, cadmium can reach to 99%,90%,90% respectively after the two-stage leaching process.Owing to considerations in requirements on separation efficiency and economic costs, a process of using zinc to replace copper in the leaching solution is adopted. The suitable operation parameters for repalcement of copper were experimentally determined: temperature in the range between 30℃and 40℃, the dosage of zinc is 1.1 times to theoretical value, and the replacement yield of 99% and a purity of cooper of 90% above can be achieved. Compared with various kinds of present methods for iron removal, ammonium persulfate(APS) is used as iron removal reagent. While the oxidation of iron is conducted under a pH value of 3.0 and a temperature of 80℃for 2 hours, with a dosage of ammonium persulfate of 2 times to theoretical value being added, the iron removal yield reach to 90% above. Finally, solvent extraction of zinc and cadmium from sulfate solutions using di-2-ethyl hexyl phosphoric acid(abbreviated as D2EHPA), in sulfonated kerosene as diluent has been studied. The effect of pH value of aqueous zinc and cadmium concentration, extractant concentration, temperature and other factors on extraction equilibrium were investigated. The results show that to achieve 90%zinc extraction yield requires three or more counter-current operation according to zinc and cadmium mixed solution. In stripping of loaded organic phase of zinc (Ⅱ), a stripping yield of 95% for zinc can be achieved under a pH of zero.To sum up the above research work, the key issues for the slags recovery was studied and solved in this paper, which can provide a guidance for the separation process of "leaching-replacement-precipitaion of impurities-extraction-stripping".
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