Abstract:SIn view of the currentSstatusSthat the arsenic content in the neutralization slag from traditional lime neutralization Fe-As coprecipitation technology is high, leading to it cannot be stored in flexible landfill, a lime milk pre-neutralization-ferrite slat precipitation method based on amorphous iron arsenate precipitation was used to lower the arsenic content in the neutralization slag obtained from the traditional technology and guarantee it can be stored in flexible landfill in this work. This method will resolve the problem of high arsenic content in the neutralization slag at the front of the traditional technology. Most of the arsenic will be removed from waste acid in the form of amorphous iron arsenate which can be further disposed by returning to copper melting furnace. The solution after arsenic precipitation was treated by sending to the traditional technology. The effects of temperature and final pH value in lime milk preneutralization process, and temperature, initial pH value, initial molar ratio of iron to arsenic, arsenic concentration, as well as type and dosage of oxidant in ferrite slat precipitation process on arsenic precipitation efficiency were investigated. The iron arsenate is stable under the pH value of 4.5～5.0 and iron hydroxide doesn"t form during arsenic precipitationSprocess. The results showed that no calcium arsenate precipitates or small amounts were produced when the final pH value was 4.5 in the lime milk preneutralization process, and the arsenic content in preneutralization gypsum was less than 3%. The arsenic concentration in the solution after arsenic precipitation should decrease and arsenic precipitation efficiency and arsenic content in iron arsenate precipitation should increase with an increase of temperature and initial pH value during arsenic precipitationSprocess using iron salt. However, it was unfavorable to the precipitation of arsenic by increasing initial Fe/As molar ratio and arsenic concentration. The oxidation rate of arsenic is slow under acidic conditions. It was difficult to obtain high arsenic precipitation efficiency using air or 80% oxygen as an oxidant. An appropriate amount of H2O2 must be added to improve the oxidation rate of As(III) ions. The arsenic concentration in the solution after arsenic precipitation, arsenic concentration in iron arsenate precipitation, and arsenic precipitation efficiency were 2.80g/L, 27.01% and 71.62% respectively under optimized conditions. The formation process of amorphous iron arsenate was controlled by precipitation reaction rate.