A clean process for recovering antimony from arsenic-bearing crystals and immobilizing arsenic as scorodite

Abstract

In this study, a clean process for recovering antimony and synthesizing scorodite was proposed to separate valuable antimony from toxic arsenic-bearing crystals produced during the alkaline oxidation of arsenic-bearing antimony white in the typical pyrometallurgy of jamesonite. The sodium antimonate was effectively leaching using dilute sulfuric acid, while the toxic arsenic was immobilized into stable scorodite. The chemical compositions of NaSb(OH)6, scorodite, and the solution were determined by inductively coupled plasma atomic emission spectrometry, The phases and microstructures were characterized using scanning electron microscope and energy-dispersive X-ray spectroscopy. By leaching using dilute sulfuric acid, 99.83% of antimony was recovered under the optimized conditions (initial pH 4.0, ratio of liquid to crystal 2.0, and leaching duration of 1 h). The recovered sodium antimonate was composed of regular cubic or rectangular crystals of 20–30 μm size. Furthermore, the toxic arsenic in the leachate was immobilized by atmospheric-pressure oxidation, where in 98.86% of the arsenic was immobilized in scorodite having a regular octahedral monocrystal with a size of 5–10 μm, and the leaching of the toxicity of the as-prepared scorodite satisfied the Chinese identification standard (GB5085.3-2007). This approach can potentially be utilized to efficiently recover antimony from complex antimony and arsenic-bearing materials or by-products while mitigating arsenic pollution caused by the metallurgical process of nonferrous metals.