COMMENTARY — SX-EW development continues

The extraordinary activity of the past decade in solvent extraction-electrowinning (SX-EW) development continues. In early 1993, at least 10 projects were under development, and another 12 had advanced to the feasibility or permitting stage. Another 14 or more are active and have development potential in the near-term. Many other producers and properties have been reported active, either for expansion of capacity already installed or for development of SX-EW operations.

There are currently 25 SX-EW plants in operation. All except four are in North America and Latin America; three are in Australia and one is in Zambia. The properties being developed are in Chile, Peru, the U.S. and Australia. The operating projects tend to be in areas with arid or semi-arid climates. Most of the capacity was developed during the past 10 years, when economic conditions drove producers to take advantage of the developing solvent extraction technology. Much of this production was originally based on processing low-grade waste dumps or old tailings, materials already mined and readily available for leaching.

Many of the producing operations have potential for long-lived SX-EW production and some have potential to increase output. In addition, some mine-for-leach operations are now in operation. Four other solvent extraction plants built to process mine or smelter materials may still be operational, including an agitated tank leach operation at the Port Pirie smelter in Australia; a heap-leach operation near Tocopilla, Chile; Sunshine Mining’s agitated tank leach in Idaho; and Centromin’s mine water processing plant at Cerro de Pasco, Peru. Altogether, the annual cathode production capacity of the operating SX-EW plants is about 780,000 tonnes.

The potential for development of cathode copper production by the leach and SX-EW route is difficult to quantify . . . Even though some have noted that perhaps only 15% of copper resources have the potential for application of leach and SX-EW technology, that potential represents a large volume . . . As technology and cathode purity have improved, SX-EW has attracted numerous junior companies, as well as the major copper producers. Its importance has grown to represent 8% of all primary copper production.

— Excerpted from a study by Pincock, Allen & Holt; the excerpt appeared in a recent company newsletter.