中国有色冶金

As arsenic in the sulfide concentrate is getting higher and higher, the arsenic content in the acidic wastewater produced by the flue gas treatment process is also getting higher and higher, and the acidic wastewater contains valuable metals such as copper and iron. At present, the method of removing arsenic from acidic wastewater is mostly for the purpose of removing arsenic, and the arsenic-containing slag formed belongs to hazardous waste and needs secondary treatment. In this study, a new process of arsenic removal by reduction was developed. Firstly, arsenic sulfide slag was added to the waste acid for copper removal and copper recovery. Then, arsenic in the solution was reduced by aluminum powder to recover arsenic. Finally, potassium sulfate was added to the arsenic removal solution to recover aluminum. After recovering the reducing agent, the final solution was treated by two-stage neutralization method. The following conclusions are obtained through experiments. Under the conditions of adding arsenic sulfide slag with 1.1 times molar amount of copper ion, reaction temperature 85℃ and reaction time 3h, the copper content in the waste acid decreased from 2000mg/L to 196mg/L, and the copper sulfide slag was returned to the smelting batching system. Under the conditions of reduction temperature of 70℃, reduction time of 2h and reducing agent dosage of 1.8 times, the reduction rate of arsenic is more than 96 %, the arsenic content in the reduced solution is less than 300mg/L, and the grade of arsenic slag is more than 95%, which can be used for the subsequent preparation of high-grade elemental arsenic. When the amount of potassium sulfate is 1.1 times, the reaction temperature is room temperature, and the reaction time is 2h, the solution contains 3.6g/L aluminum, and the obtained alum can reach the first-class product standard of ‘industrial aluminum potassium sulfate’ ( HG/T2565—2007 ). This method has good arsenic removal effect, and can convert arsenic in waste acid into arsenic products, and will not produce hydrogen sulfide gas, which has application and promotion value.