Abstract
In order to realize the stepwise extraction of Zn, In and Pb from secondary zinc oxide dust, the thermodynamic analysis of wet leaching was carried out, and the multi-stage combined wet treatment process of “low acid leaching-high acid leaching-chlorination leaching” was formulated; secondary zinc oxide dust was used as the experimental raw material to explore the optimal process conditions for the stepwise extraction of Zn, In and Pb. The experimental results show that: using low acid leaching to treat the secondary zinc oxide dust, sulfuric acid mass concentration of 100 g/L, liquid-solid product mass ratio of 5 mL/1·g, leaching time of 90 min, leaching temperature of 60 ℃, stirring speed of 500 r/min, and a single leaching conditions, the Zn leaching rate of more than 70%, the mass fraction of In, Pb increased to 0.052%, 10.8%, respectively, to achieve a 3.71 times, 2.45 times enrichment effect, respectively; When the high acid leaching treatment was used to treat the low acid leaching residue, the sulfuric acid concentration was 170 g/L, the liquid-solid volume mass ratio was 7 mL/1·g, the leaching time was 4 h, the leaching temperature was 80°C, the stirring speed was 500 r/min, the leaching rate of In was more than 90%, and the Pb mass fraction was increased to 40.12%, which achieved a comprehensive enrichment effect of 8.96 times. The high acid leaching residue was treated by chlorination leaching method, and the Pb leaching rate was greater than 93% under the conditions of pH value of 3, leaching temperature of 80°C, liquid-solid volume mass ratio of 12 ml/1·g, Cl− concentration of 7 mol/L, leaching time of 2 h, and stirring speed of 500 r/min, and the gradient separation of Zn, In and Pb was preliminarily realized.