Pressure Oxidation Dissolution of Antimony Trioxide in KOH Solution for Preparing Sodium Pyroantimonate

To overcome the shortcomings of the traditional method, a novel method was proposed to produce sodium pyroantimonate (NaSb(OH)(6)) with antimony trioxide by pressure oxidation in KOH solution. An E-pH diagram of the Sb-H2O system at different temperatures indicated that various forms of Sb (III) can be easily oxidized to Sb (V) in alkaline solution at high temperature, generating potassium pyroantimonate. The results demonstrated appropriately increasing temperature, oxygen partial pressure, stirring speed, KOH concentration and duration time were beneficial to increasing the Sb leaching ratio. However, a new precipitate could be produced from the leaching solution by excessive temperature. Finally, NaSb(OH)(6) should be prepared by adding NaOH in time to avoid the formation of KSbO3 with temperature lowering. The Sb precipitation ratio reached 90.32% under optimal conditions. The results of SEM and particle distribution showed that NaSb(OH)(6) is a regular hexahedron with an average particle size of 6.13 mu m.