Abstract Arsenic removal from arsenic-bearing purified residue by alkaline pressure oxidative leaching (APOL) and reduction of arsenate in solution to arsenite by sulfur dioxide gas was studied. The effects of different parameters including NaOH concentration, oxygen partial pressure, temperature, liquid/solid ratio, and leaching time for the extraction of arsenic were investigated based on thermodynamic calculation. The optimum leaching conditions have been established as: 2.5 mol/L of NaOH concentration, 0.5 MPa of oxygen partial pressure, 120 °C of temperature, 4 mL/g of liquid/solid ratio and 3.0 h of time. Under these conditions, the leaching rates of arsenic, zinc and nickel respectively reached 94.47%, 19.90% and 12.66%, while copper and cobalt were hardly leached out, achieving the selective removal of arsenic from the arsenic-bearing purified residue. The reduction of As(V) in solution was optimized by orthogonal experimental design method, and the effects of experimental parameters including initial pH, reduction temperature (T), flow rate of SO2 (F), and reduction time (t) on reduction of As(V) were investigated. The results show that the optimum reduction parameters were 4 of initial pH, 30 °C of temperature, 60 mL/min of SO2 flow rate and 2.5 h of time. Based on these conditions, the reduction rate of As(V) reached 92.95%.

中文翻译：

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碱压氧化浸出和还原砷（V）对含砷纯化渣中砷的去除和再利用

摘要 研究了碱性压力氧化浸出(APOL)法去除含砷纯化渣中的砷和二氧化硫气体将溶液中的砷酸盐还原为亚砷酸盐。基于热力学计算研究了NaOH浓度、氧分压、温度、液固比和浸出时间等不同参数对砷提取的影响。最佳浸出条件为：NaOH浓度2.5 mol/L，氧分压0.5 MPa，温度120℃，液固比4 mL/g，时间3.0 h。在此条件下，砷、锌、镍的浸出率分别达到94.47%、19.90%和12.66%，而铜和钴几乎没有浸出，实现从含砷纯化残留物中选择性去除砷。采用正交实验设计方法对溶液中As(V)的还原进行优化，考察初始pH、还原温度(T)、SO2流量(F)、还原时间(t)等实验参数对还原反应的影响。 As(V)进行了研究。结果表明，最佳还原参数为初始pH值、温度30°C、SO2流速60 mL/min和时间2.5 h这4个。基于这些条件，As(V)的还原率达到了92.95%。结果表明，最佳还原参数为初始pH值、温度30°C、SO2流速60 mL/min和时间2.5 h这4个。基于这些条件，As(V)的还原率达到了92.95%。结果表明，最佳还原参数为初始pH值、温度30°C、SO2流速60 mL/min和时间2.5 h这4个。基于这些条件，As(V)的还原率达到了92.95%。