Eliminating arsenic impurities from high-purity antimony trioxide through potassium sulfide co-precipitation

Arsenic, a significant impurity in high-purity antimony trioxide (Sb2O3), has historically been challenging to eliminate efficiently. This paper introduces a novel hydrometallurgical method capable of effectively reducing arsenic levels to below 0.1 ppm through sulfurization precipitation. This technique involves the co-precipitation of antimony ions (Sb3+), arsenic ions (As3+), and sulfide ions (S2-) to form antimony trisulfide (Sb2S3) and arsenic trisulfide (As2S3), consequently reducing the arsenic content in Sb2O3 to below 0.1 ppm. This method offers an effective solution for arsenic removal. The findings reveal that a high concentration of Sb3+, H+, and an excess of potassium sulfide (K2S) promote the formation of precipitates, thus enhancing the removal of arsenic. Temperatures below 30 degrees C are also conducive to the formation of As2S3. The addition of excess ammonia water alters the final product from Sb4O5Cl2 to Sb2O3, influencing the product's phase. This study presents an innovative and efficient hydrometallurgical technique for removing arsenic from high-purity Sb2O3, addressing a significant gap in this field. It offers practical guidelines for reagent dosing and shows substantial promise for industrial application.