Development of an effective colloidal regime for the electrorefining of copper anodes at high current densities

One of the ways to increase the efficiency of copper refining production is to increase the cathode current density. Operation at high current densities (300 A/m2 or more) allows for increased conversion productivity. However, intensive process management has a negative effect on the appearance of cathode products and leads to the formation of defects on the surface of the cathode web (dendrites and rounded growths). In addition, the presence of these defects significantly increases the risks of increasing the content of impurity components in the cathode metal, due to the loose dendritic structure of the cathode, in which electrolyte residues can accumulate. A technical solution is proposed that makes it possible to stabilize the regular appearance of copper cathodes when operating at high current densities by optimizing the consumption of special colloidal additives and the composition of the electrolyte used. As a result of previous studies, it was found that the preservation of quality indicators at current densities up to 340 A/m2 can be achieved with the following electrolyte composition, g/dm3: 53–55 Cu; 160–170 H2SO4; 20–24 Ni; 0.050 Cl–. To select the optimal flow rate of colloidal additives, laboratory studies were carried out in the current density range of 300–340 A/m2 and the following flow rates of colloidal additives, g/t: 80–110 of hide glue; 65–80 of thiourea; 50–60 of thiourea, pre-soaked in a copper electrolyte at a temperature of 50–60 oC for 24 hours. The optimal consumption of colloidal additives for each of the studied current densities is presented, ensuring a minimum number of surface defects and an optimal content of impurities in copper cathodes.The authors express special gratitude for their participation in the work to the head of the copper electrolysis workshop of the Copper Plant of the Polar Branch, S. O. Tyulenev, and the head of the technical department of the Copper Plant of the Polar Branch, K. E. Voronin.