Behaviour and mechanism of selective removal of As and Sb fr 2027 Minerals E

Tetrahedrite [(Cu,Fe)12(As,Sb)4S13], a Cu-rich polymetallic sulfide, contains high levels of As and Sb (contains As 5.12%, Sb 11.46%) that resist physical beneficiation, impairing concentrate quality and burdening smelting with environmental and operational challenges. To address this cleaner production challenge, we propose an innovative ultrasonic-enhanced alkaline leaching process for the selective removal of As and Sb from tetrahedrite. The effects of ultrasonic power, leaching agent concentration, liquid-solid ratio, and reaction time on removal efficiencies were systematically investigated. The underlying mechanism was elucidated through X-ray diffraction (XRD), scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS), and far-infrared (FIR) spectroscopy. XRD analysis revealed the near-disappearance of tetrahedrite characteristic peaks and the emergence of new copper-iron sulfide phases (CuS, (Fe,Cu)S2, Cu2S, and CuS2), while FIR spectra confirmed the cleavage of (Sb/As)-S bonds. Microscopic observations showed that the originally intact and crack-free crystal surfaces evolved into highly porous, honeycomb-like structures after leaching, facilitating efficient impurity removal. Under optimized conditions (NaOH-Na2S = 3.84 mol/L + 1.92 mol/L, ultrasonic power 500 W, liquid-solid ratio 25:1, time 6 h), the leaching rates of As and Sb reached 97.35% and 97.14%, respectively, with residual contents as low as 0.152% As and 0.368% Sb—well below the smelting standard for copper concentrates (As < 0.5%, Sb < 0.5%). This work demonstrates an efficient and selective strategy for the cleaner detoxification of high-As and high-Sb tetrahedrite.