Formation of antimonate in co-precipitation reaction of As, Sb and Bi in copper electrolytes

A synthetic copper electrolyte containing Cu2+, H2SO4, As(III), Sb(V) and Bi(III) ions was purified at 65 °C and 300 rpm stirring for 2 h. It was found that the removal rates of As, Sb and Bi reached 40.6%, 82% and 43.3%, respectively in this electrolyte. The electrolyte was filtered and the precipitate structure, morphology and composition were analyzed by means of chemical analysis, SEM, TEM, EDS, XRD and IR. The precipitate in the form of irregular lump with size ranging from several to tens microns mainly consists of As, Sb, Bi and O elements. The characteristic bands in the IR spectra of the precipitate are As–O–As, As–O–Sb, Sb–O–Bi, Sb–O–Sb, Bi–O–Bi and O–H. XRD and electron diffraction show that the precipitate is a mixture precipitate composed of amorphous phases and crystalline mixtures of BiSbO4 and AsSbO4. The precipitate deposits quickly in the bottom of container due to the large size. Additionally the crystalline of AsSbO4 and BiSbO4 was also found in the residue of larox filter in the electrorefining plant of copper smelter, which indicates that the formation of antimonate plays an important role in the removal of As, Sb and Bi impurities from copper electrolytes.

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► Precipitation reactions happen in solution containing As(III), Sb(V) and Bi(III).
► Antimonate plays important role in As, Sb and Bi removal from copper electrolytes.
► The finding of antimonate in larox filter residue of copper electrorefining.