The Use of Antimony Trioxide in Copper Electrolyte Purification and Its Subsequent Regeneration: An Experimental and Mechanistic Study

Resumo

The removal of As, Sb, and Bi impurities from copper electrolyte is a primary objective of copper electrorefineries. The present experimental work demonstrates that the presence of Sb₂O₃ facilitates efficient and fast removal these impurities (with removal rates of 38.50, 98.50, and 99.00% for As, Sb, and Bi) through the formation of antimonate (AsSbO₄/Sb₂O₄/BiSbO₄), which plays a critical role in the self-purification of copper electrolyte. However, the antimonate which is a valuable metallurgical by-product contained high contents of As and Sb. The thermal decomposition of the antimonate was characterized by TG/DTA, a new method was proposed for recovering the target components, As, Sb, Bi, and to regenerate Sb₂O₃ with a two-stage roasting process under argon atmosphere. According to the results of XRD, SEM-EDS and ICP-MS, AsSbO₄ decomposed during the first stage roasting at 800°C over 2 h, affording As with a recovery rate of 98.80%. During the second stage, decomposition of BiSbO₄ and Sb₂O₄ at 1200°C over 2 h resulted in 99.01, 95.14% recovery rates for Sb, Bi.