Electrowinning set to emerge as major new method of recovery

Electrowinning, the recovery of metals from ore by means of electrochemical processes, will account for about 20% of total refined copper production by the year 2000, according to a Commodities Research Unit (CRU) study, Copper Leach Electrowinning in the 1990s: Pace of Growth, Cathode Quality, Plant-by-Plant Costs. Electrowon copper cathodes are becoming increasingly popular at some U.S. wire mills, the study says, because they are free of the impurities — such as antimony, arsenic and bismuth — found in conventional electrolytic cathode. With good quality control, electrowinning can also reduce levels of lead, iron and sulphur that have traditionally created problems for wire producers.

Because electrowinning is generally cheaper than the conventional electrolytic refining technique, which uses electric currents to extract metals from ore, the new method may force high-cost conventional producers out of business.

The study cautions, however, that the electrowinning process is dependent on the availability of sulphuric acid, a commodity that is often in short supply.

At the moment, high-quality electrowon cathode is derived mainly from heap leach operations in the U.S. But Chile is expected to increase production significantly from its heap leach operations in the near future, the study says.

The CRU study is available from Commodities Research Unit Ltd., 31 Mount Pleasant, London, England WCX OAD.