Green and Effective Purification of Antimony and Recovery of Precious Metals from Noble Antimony by a New Vacuum Gasification Process

Abstract

Noble antimony is the carrier of precious metals in the antimony smelting system and has a very high added value. This study proposes a novel, green, and effective vacuum gasification process for purifying antimony and recovering precious metals from noble antimony. Saturated vapor pressure and separation coefficients (β) were used to qualitatively analyze the possibility of separating elements from noble antimony, while vapor–liquid equilibrium (VLE) phase diagrams were used to quantitatively predict the degree of separation of alloying components and resulting product compositions. The effects of temperature and holding time on the antimony purity and the recovery efficiencies of Au and Ag were investigated by vacuum gasification experiments. The experimental results revealed that at an optimal temperature of 1123 K, the antimony purity in the volatiles was 99.41 pct. In the residues, the Au content was 11300 g/t and the recovery efficiency was 99.62 pct. Further, for Ag, these values were 2300 g/t and 66.56 pct, respectively. At an optimal holding time of 120 minutes, the antimony purity in the volatiles was 99.63 pct. In the residues, the Au content was 12100 g/t with a recovery efficiency of 99.75 pct, whereas the Ag content was 2600 g/t with a recovery efficiency of 67.12. Valuable metals in noble antimony are effectively purified and recovered via the vacuum gasification process without generating any waste gas and water. This work provides guidance for the separation of antimony and precious metals via the vacuum gasification of noble antimony, aligning with the principles of cleaner production. Graphical Abstract: [Figure not available: see fulltext.]