High concentration of arsenic removal from acid leaching solution of zinc oxide dust by water-quenched slag

Abstract

The present work provides a study on high concentration of arsenic removal from acid leaching solution of zinc oxide dust by water-quenched slag. The water-quenched slag is a waste slag produced from fuming furnace of lead pyrometallurgical process and used as a substitute of ferrous sulfate heptahydrate to precipitate arsenic at purification section. The effects of reaction temperature, reaction time, the addition of H2O2 and the addition of water-quenched slag on arsenic removal rate were systematically investigated. The reaction temperature of 70°C, reaction time of 1 h, H2O2 addition of 10.8 mL/L and water-quenched slag addition of 17.8 g/L are identified as the best technical parameters. At the optimum conditions, the arsenic (III) with high concentration (As 4.13 g/L) is efficiently removed (arsenic removal rate > 99%). The filtrate (Fe 1.21 mg/L, As 1.53 mg/L) with low concentrations of arsenic and iron and the stable filter residue are also obtained successfully. The United States EPA Toxicity Characteristic Leaching Procedure (TCLP) test shows that the As leachability never exceeds the regulatory limit of 5 mg/L As. The results suggest that the water-quenched slag shows potential for removing high concentration of arsenic from acid leaching solution of zinc oxide dust.