Abstract:Hexavalent chromium (Cr(VI)) is a heavy metal compound with strong oxidizing property and high toxicity. This work analyzes the sources of Cr(VI) generation in the ferrite magnetic powder process. By utilizing the oxidation-reduction method to reduce Cr(VI) to Cr(III), the effects of different reducing agents on the treatment of Cr(VI) in ferrite magnetic powder were investigated. Experimental results indicate that Cr(VI) in ferrite magnetic powder is primarily generated during the tempering process. Ferrous sulfate, sodium thiosulfate, and ferrous oxalate can all serve as reducing agents to reduce Cr(VI) to Cr(III). Among them, sodium thiosulfate exhibits the best treatment effect, the content of Cr(VI) is down to below 10 mg/kg when added at a concentration of 0.3%~0.8%. When the addition amount is greater than 0.8%, continuing to increase sodium thiosulfate actually increases the content of Cr(VI). The treatment effect of ferrous sulfate is moderate. Whereas the treatment effect of ferrous oxalate is relatively poor, requiring an addition amount of 1.2% to reduce the hexavalent chromium content below 10 mg/kg. Considering economic cost, the combined addition of ferrous sulfate and sodium thiosulfate can effectively reduce Cr(VI) in magnetic powder, offering higher cost-effectiveness and practicality. The oxidation-reduction method has little effect on the magnetic property of ferrite magnetic powder. The oxidation-reduction method in this work not only effectively reduces the Cr(VI) content in ferrite magnetic powder, ensuring it consistently meets industry standards, but also effectively controls costs and enhances quality. It provides a reference solution for the entire industry and has significant guiding significance for the treatment of Cr(VI) in industrial production and pollution control.