Mechano-Chemical Assisted Stabilization and Detoxification of Arsenic and Antimony in Arsenic-Alkali Residue

Toxic elements such as arsenic (As) and antimony (Sb) in the arsenic-alkali residue resulted from the antimony smelting industry posed a threat to the ecosystem and must be properly treated to prevent their release into the environment. The integration of stabilizers into mechano-chemical approaches has emerged as a highly promising strategy for the detoxification of non-ferrous metal smelting slags, drawing increasing research attention in recent years. Meanwhile, zero-valent iron has been widely applied owing to its low cost, ready availability, and high reactivity. In this study, modified zero-valence iron powders (ZVI) were prepared and employed to stabilize As and Sb in the arsenic-alkali residue via a mechanical ball-milling process. After modification using acetic acid, the surface properties of the iron powders were substantially altered, leading to the formation of iron oxides. The optimum operation conditions for the mechanical ball-milling process were determined as follows: a milling time of 1 h, the dosage of the detoxifier (nAs:nFe) of 1:1, and a ball-to-material ratio of 6:1. Under these conditions, the leaching toxicity of the As and Sb were 1.483 mg/L and 0.208 mg/L, respectively. The stabilization of As and Sb in the residue was primarily attributed to their adsorption onto the surface iron oxides and the formation of new insoluble phases during the ball-milling process.