The U.S. Department of Energy investigated the use of liquid-emulsion membranes (LEM) for the selective removal and recovery of metals such as copper and zinc from mine waste waters. This investigation included field tests of a mobile, pilot plant-scale, continuous-flow LEM system. The system was tested at copper mines with solutions containing from 100 to 1,400 ppm Cu, and at a zinc mine with a solution containing 115 ppm Zn. Typical results from the copper tests were >90 percent copper recovery, and zinc extraction from waste water also was typically >90 percent. Although all of these waste waters contained high impurity levels, pure products were produced. On several of these field tests, integrated systems were tested that resulted in recovery of metal by-products, selective precipitation of iron, and polishing to reach discharge targets for essentially all of the contained metals. In addition, some results are included from laboratory-scale tests.
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