从高炉瓦斯泥中湿法回收锌的新工艺(Ⅱ):溶剂萃取及电积

A New Process for Recovering of Zinc From Blast Furnace Sludge(Ⅱ): Solvent Extraction and Electrowinning

针对钢铁厂瓦斯泥硫酸浸出液中和除铁后的溶液含锌低、含杂质高、不能直接电积的特点,选用萃取—电积工艺富集回收锌。萃取采取三级逆流萃取、两级逆流洗涤、两级逆流反萃取工艺,以40%P204+260#煤油为有机相,控制有机相与水相的流量比为2∶1,萃取温度维持在40℃;洗涤采用去离子水、废电解液加去离子水(pH≈2)两步逆流洗涤法,温度为40℃;反萃取剂为H2SO4质量浓度160g/L、锌质量浓度50g/L的溶液,反萃取有机相与水相的流量比为(4～5)∶1,反萃取温度为40℃。反萃取液经纤维球除油+两次活性碳(2g/L)除油之后通过电积得到金属锌板,锌板中锌质量分数为99.97%,电积时电流效率为90.48%。

The ZnSO4 leaching solution of blast furnace flue dust removed ferric contains zinc and some impurities,which can not be directly used in zinc electrowinning. In this article,the process of solvent extraction and electrowinning was selected to enrich and recover zinc. Extraction process comprised of three-steps countercurrent extraction,two-steps eountereurrent washing and two-steps countercurrent stripping. Organic phase composition was 40 % P204 -1- 260 kerosene,Vo/V1 = 2/1, temperature was 40℃. The loading organic phase was two-steps washed using deionized water and diluted waste electrolyte（pHi2） by adding deionized water respectively at the conditions of 40 ℃,Vo/Va of 5/1. Stripping of the loading organic phase was conducted using spent electrolyte （p（Zn2＋） ≈50 g/L, p（H2SO4）≈160 g/L） at the conditions of 40 ℃, Vo/Va of （4-5）/1. To meet the requirement of zinc electrowinning,entrained organic phase in the ZnSO4 solution was removed by a step of fiber ball absorption and two-steps of activated carbon （2 g/L） absorption. Finally, the stripped solution was used to electrolyze zinc . The zinc plate contained 99.97% zinc, the current efficiency was 90.48%.