A novel process for separating arsenic and antimony from arsenic-antimony dust via leaching with oxalic acid solution

The separation of arsenic and antimony from arsenic-antimony dust is challenging and critical for the efficient antimony recovery. Herein, we propose a novel process to separate arsenic from arsenic-antimony dust based on one-step selective leaching. Various inorganic and organic lixiviants have been screened for this purpose, among which oxalic acid leaching enables the highly selective arsenic removal to the pregnant leach solution and the enrichment of antimony in the leaching residue. Under the optimized conditions: temperature 30 degrees C, oxalic acid concentration 0.4 mol center dot L- 1, liquid-to-solid ratio 15 mL center dot g- 1, and leaching time 60 min, the arsenic removal yielded 99.0 % with only 0.68 % Sb loss into the leachate. Raman spectroscopy analysis revealed that arsenic trioxide dissolves by forming arsenious acid in the acidic solution, whereas antimony trioxide in the dust transforms into antimony oxalate hydroxide in the leaching residue. The thermal instability of antimony oxalate hydroxide on heating facilitates its subsequent decomposition to cubic antimony trioxide at around 300 degrees C. Overall, this study presents a viable approach for selective arsenic removal and antimony recovery from arsenic-antimony dusts.