One-step purification of crude antimony by vacuum distillation-selective condensation

Abstract

The traditional distillation technology typically employs a two-step distillation process to remove highly and lowly volatile impurities from antimony (Sb) metal. Based on the impurity behavior model during the vacuum distillation purification of Sb metal, a one-step technology for producing high-purity Sb metal via vacuum distillation-selective condensation has been developed. This technology was applied to prepare 4 N5(99.995 %) and 4 N(99.99 %) high-purity Sb metals at three distillation temperatures of 640 °C, 670 °C, and 700 °C. The research findings indicate that highly volatile impurities such as arsenic (As) migrate into the distillate in the upper section, while lowly volatile impurities such as bismuth (Bi), lead (Pb), copper (Cu), iron (Fe), and nickel (Ni) are enriched in the residue in the lower section. Compared with traditional distillation technology, the vacuum distillation-selective condensation method can effectively remove both highly and lowly volatile impurities. Specifically, lowly volatile impurities such as Cu, Fe, Ni, and Pb were significantly removed with removal rates exceeding 85 %, whereas the removal rates for highly volatile impurity of As and lowly volatile impurity of Bi were limited, with the lowest removal rate being approximately 50 %. The distillation temperature is preferably set at 640 °C, where the maximum product yield reaches 83.16 %. In one-step preparation, the yields of 4 N5 and 4 N high-purity Sb metals are 32 % and 51.16 %, respectively.