As part of its in situ mining research program, the U.S. Bureau of Mines is conducting core-leaching experiments on oxide copper ores to assess solution-rock interactions occurring during in situ mining. Two sets of experiments were conducted on two different types of ores. Three experiments were conducted on a granodiorite porphyry chrysocolla ore, which contained cu in both disseminated and fracture-hosted chrysocolla, as well as in clay-altered plagioclase phenocrysts. The experiments were conducted using 5, 15, and 25 g/l h2so4 leach solutions. Three experiments were also conducted on a quartz monzonite atacamite ore, which contained all cu in fracture-hosted atacamite. These experiments were conducted using 10-, 20-, and 40-g/l h2so4 leach solutions. The chrysocolla experiments resulted in the mobilization of not only cu, but also significant amounts of ca, al, and fe. By contrast, the atacamite experiments resulted in very minor mobilization of ions other than cu. Details of the fluid chemistry resulting from these experiments are presented, along with a discussion of how the leaching characteristics are related to the rock and ore type.
Engineering Foundation Conf., Santa Barbara, California, Oct 25-30, 1987; Eng. Foundation, PP. 113-134