An investigation of the influence of selenium on copper deposition during electrorefining using electrochemical noise analysis

The influence of selenium impurities on copper deposition at 65 °C in industrial sulfuric acid electrolyte (standard) was investigated using electrochemical noise analysis and cyclic voltammetry in conjunction with scanning electron microscopy and X-ray diffraction. The results were compared with those obtained with synthetic electrolyte containing thiourea and gelatin additives. The presence of selenium ions in the standard electrolyte and the electrolyte containing additives resulted in a spongy and porous copper deposit covered by a non-adherent black powder of copper–selenium compounds. The measured statistical parameters of skewness and kurtosis of the EN signals correlated well with the presence of the spongy morphology on the cathode surface.

► The influence of selenium impurities on copper deposition was investigated using EN analysis. ► Both standard electrolyte and electrolyte with additives resulted in a non-adherent black powder. ► The black powder was identified as Cu–Se compound that covers the surface of deposits. ► The statistical analyses of the EN signals correlated well with the presence of the cathodic spongy morphology.