Two-stage leaching of zinc and copper from arsenic-rich copper smelting hazardous dusts after alkali leaching of arsenic

Abstract

In order to efficiently recover zinc and copper from arsenic-rich copper smelting hazardous dusts after alkali leaching of arsenic, an optimum two-stage leaching process by using sulfuric acid media was developed in this study. The leaching behaviors of zinc, copper, arsenic and iron under different experimental conditions (such as: leaching time, temperature, sulfuric acid concentration and oxidant addition), were studied systematically. The results indicated that 98.4% zinc and 96.01% copper were leached using the first-stage of neutral leaching under conditions including final pH 5.0 ± 0.1, time 1 h, temperature 90 °C and the second-stage of sulfuric acid leaching under conditions including initial sulfuric acid concentration 190 g/L, leaching time 2 h, temperature 90 °C and 1.4 times oxidant addition. Meanwhile, 99.58% lead and 98.93% bismuth were remained in the sulfuric acid leaching residues which can be recovered by pyrometallurgical processes. The leaching behavior relationships among copper, zinc, arsenic and iron were also modeled. Results indicated that the ferric ion improved copper and zinc leaching. SEM study demonstrated that the leached surface was corroded, and EDS and XRD results indicated that zinc and copper oxides were disappeared during leaching while lead oxide was transformed into anglesite, and tin oxide was remained in the residues.