Enhanced alkaline leaching of arsenic in lead anode slime using shearing jet aeration reactor

In this study, alkaline leaching enhanced by shearing jet aeration reactor was employed to remove arsenic from lead anode sline. The effects of various parameters, such as liquid/solid ratio, concentrations of sodium hydroxide solution, leaching time and temperature, on leaching ratios of different metals were investigated. On this basis, the optimal conditions was obtained through orthogonal experiment, namely, 1.0 mol/L NaOH, a liquid/solid ratio of 6:1, leaching at 70 ℃ for 1 h. Under this optimal condition, the leaching rate of As reached up to 95.0 %, and that of Pb and Sb was less than 2.0 % and 1.0 %, respectively, while Bi was hardly dissolved in alkaline solution. In addition, arsenic-containing leachate could be treated with lime and removal rate of As in leachate exceeding 85 %. Then, the filtrate from lime precipitation was recycled and reused in leaching process. Also, a satisfying result could be obtained with more than 95 % of As leaching rate after the filtrate was recycled. Compared with the conventional alkaline leaching for As removal, this process could decrease the dosage of sodium hydroxide, shorten the leaching time, and efficiently improve the separation rate of arsenic and other valuable metals. It can be concluded that the shearing jet aeration reactor can be applied to the pretreatment of arsenic-containing materials and obtain a high leaching rate of arsenic.