Copper refining electrolysis at high current densities

In this study, the possibility of utilizing high current densities in copper refining electrolysis was investigated in relation to the cell design along with the surface characteristics of cathode material, and the changes observed in cell potential depending on the working conditions. Two groups of experiments were conducted. The first series of copper refining electrolyses were carried out without any additives to the bath whereas in the second series, the effect of glue, thiourea, and chloride additions to the bath on cathodic copper was examined. Electrolysis conditions, in accordance with industrial practice, kept constant in both sets of experiments and were as follows: 45 g Cu ²⁺/L, 150 g H₂SO₄/L, 55°C, electrolyte circulation of 15-20 L/min, anode dimensions of 78×74×4.5 mm, copper cathode of 47×85×0.1 mm, current density of 700 A/m², and the aforesaid additives. Lab-scale high current density copper refining electrolysis was carried out in a, specially designed cell with a unique electrolyte feeding system and small amount of additives to the bath, resulting in considerably high current efficiencies (≈99%).