Antimony Vaporization and Condensation in Simulated Flash Smelting Off-Gas Train Conditions

Antimony is one of the most deleterious impurity elements in copper smelting and has a strong tendency to vaporize in the smelting furnace resulting in an enrichment of antimony in smelter flue dusts. The vaporization and condensation behavior of antimony species was studied in dust-free conditions simulating the off-gas train of a Flash Smelting Furnace at temperatures below 1273 K (1000 °C). The influences of the oxygen partial pressure and the condensate formation temperature on the characteristics of the precipitated antimony species were determined. It was found that practically all the vaporized antimony species precipitated between 853 K and 546 K (580 °C and 273 °C) and that a higher oxygen partial pressure favored precipitation at higher temperatures. The formation of antimony sulfate, which thermodynamically is the most stable antimony species in the studied conditions at temperatures below approximately 723 K (450 °C), was found to be kinetically constrained and the vaporized antimony species precipitated as oxides or sulfides depending on the oxygen partial pressure and the precipitate formation temperature.