Selective Separation of Antimony and Preparation of Sodium Antimonate by Sodium Salt Leaching-Synergistic Oxidation from High Arsenic Antimony Residue

In this study, the catalytic air oxidation method was used to selectively form sodium antimonate from an antimony residue Na2S-NaOH leaching solution of a high arsenic copper anode slime. In the first stage, the leaching process with Na2S and NaOH media resulted in more than 98% leaching of antimony. The synergistic oxidation method was used to selectively separate antimony in the second stage. In this study, the oxidation rate of antimony was greater than 98% at the NaOH concentration of 50 g·L−1 and a combined oxidation concentration of 0.75 g·L−1 catechol + 0.75 g·L−1 KMnO4, under the air flow rates of 1.415 m3·min−1 at 75 °C for 8 h. The pH of the crude sodium antimonate product was adjusted; subsequently, it was redissolved and precipitated to prepare refined sodium antimonate that meets the secondary product standard of China’s non-ferrous metal industry, which recommends an antimony recovery rate of >95.60%. After neutralisation, the liquid contains [As] < 0.10 g·L−1, [Sb] = 0.16–0.38 g·L−1, which can be reused in the composite leaching process. The apparent activation energy (Ea) of the catalytic oxidation reaction was 6.47 kJ·mol−1; the results suggested that the reaction process was diffusion controlled. −dSbdt=8.86×10−5×e−778.44T×Sb0.4906×[NaOH]1.190.