Antimony recovery from antimony-rich slag by top blowing nitrogen into the molten slag bath

Abstract

We study the evaporation of antimony trioxide from an antimony-rich slag by bubbling nitrogen gas through a submerged top lance at 1000–1300 °C. Experiments are carried out with 300 g slag at gas flow rates of 20–60 l/h with the lance height of 1.5 and 10 mm. Slag samples are taken and analyzed to identify changes in the antimony trioxide content during the evaporation. By fitting the antimony trioxide content evolution of the slag to the calculation according to the integrated rate law, the antimony trioxide evaporation under the present conditions is found to be a second-order reaction. The evaporation rate constants and Sb recovery are enhanced with increasing temperature and gas flow rate and decreasing lance height. The deposited antimony trioxide product is characterized to determine its impurity level and microstructure. The rate-limiting step of the antimony trioxide evaporation is discussed, and the residual slag is analyzed to understand the antimony trioxide evaporation limits.