Pressure oxidation of sodium thioantimonite solution to prepare sodium pyroantimonate

• Sodium pyroantimonate was prepared by pressure oxidation.
• The effects on the Sb precipitation ratio and different S ion distribution ratios were investigated.
• NaOH concentration and temperature affect the morphology of sodium pyroantimonate obviously.

Sodium pyroantimonate was prepared by pressure oxidation from sodium thioantimonite solution. The effects of temperature, NaOH concentration, oxygen partial pressure, stirring speed and reaction time on the oxidation precipitation ratio of antimony and the distribution ratio of different sulfur ions were investigated during pressure oxidation. The morphology of sodium pyroantimonate was analyzed by SEM. The optimum conditions were as follows: 20 g/L [NaOH], 800 rpm stirring speed, 400 kPa oxygen partial pressure, 60 min reaction time and 90 °C reaction temperature. Under such optimum conditions, the precipitation ratio of antimony was 99.38% and the distribution ratio of sodium thiosulfate was 84.13%, and the morphology of the synthesized sodium pyroantimonate was similar to regular hexahedron with an average particle size of 69.33 μm.