Copper Refining Electrolyte and Slime Processing - Emerging Techniques

Copper electro-refining (Cu-ER) is the principal method for producing >70% of high or 99.97% pure copper cathodes from 97-99% pure blister/fire refined-scrap copper anodes. While the inert and most of less soluble impurities settle as anode slime/sludge, other soluble impurities, particularly the metalloids (group VA/15 elements or Q: As, Sb and Bi) and some transition metals (Mt) co-dissolved with Cu(II). Since the soluble impurities build up in the copper refining electrolyte (CRE) which need monitoring and control to prevent contamination of the cathodes and passivation of the anodes before bleeding for spent CRE reprocessing. There is a high demand for pure electrorefined copper and electrolyte additives are used to the CRE to prevent nodulation or control the chemical and physical properties of copper cathodes. Various hydrometallurgical methods such as precipitation, adsorption, electro-dialysis, electro-winning, ion exchange and solvent extraction have been developed with some success to control the CRE impurities. So, some emerging technologies for improved monitoring and control of the metalloid impurities in CRE and slime as well as development of saleable byproduct recovery (As, Sb, Bi) are briefly reviewed with particular emphasis on the precipitation for the metalloid slime resource recycling and product development.