• Hydrometallurgy of the delta sulfide ores, first stage report

      Letwoski, F.; Chous, Kuo-tung; Rao, P.D. (University of Alaska Mineral Industry Research Laboratory, 1986)
      This report presents the results of hydrometallurgical research carried out from September 16, 1985 to June 30, 1986 on metals recovery from complex sulfide ores from the Delta deposit near Tok, Alaska. The leaching characteristics performed for 6 different ore samples indicate that the most valuable components form the following order: Zn > Au > Pb > Ag > Cu > So. Further study demonstrates that direct leaching of the ore is effective both in chloride as well as in sulfate oxidizing solutions coupled with separating of leached solid components by flotation. Three variants of the ore processing with ferric chloride or fenic sulfate leaching are analyzed: one flowsheet with direct ore leaching in ferric chloride solution followed by leaching-flotation step, with subsequent zinc separation in a solvent extraction step and electrolysis in chloride solution; and two flowsheets of direct ore leaching with ferric sulfate solution followed by a leaching-flotation step, with zinc sulfate electrolysis and other metals recovery in chloride leaching sreps. In two last flowsheets silver is recovered during the chloride leaching steps and gold h m flotation products during the cyanide leaching. Preliminary economic and technical evaluation is presented. The engineering study on apparatus for the fast leaching- flotation processing and on better accumulation of gold and silver in one semi-product are concluded for the next year of research.
    • Oxygen application to chloride leaching of complex sulfide ores

      Chou, Kuo Tung (University of Alaska Mineral Industry Research Laboratory, 1987)
      The study investigates leaching of complex sulfide ores with simultaneous regeneration of the leaching solution and removal of dissolved iron to balance the iron concentration in the leaching process. To minimize environmental pollution and obtain high metal extraction from the ores, leaching with a ferric chloride solution is adapted to treat Delta sulfide ores. The experimental results indicate that under high oxygen pressure leaching, oxidation of ferrous ion to ferric ion and partial precipitation of iron from solution can occur simultaneously. However, the findings also indicate that leaching the ores with simultaneous iron precipitation in one operation is difficult. It is better to precipitate excess iron in one stage; then leach the ores in another stage using the regenerated leaching solution.