• Analysis and comparison of cyanide detoxification methods from spent heaps

      Kroeger, Edwin Bane; Huang, Scott L.; Nelson, Michael G.; Bandopadhyay, Sukumar; Braddock, Joan F.; Chen, Gang; White, Daniel H. (1997)
      This work entailed the testing of cyanide degradation of microorganisms isolated by the U.S. Bureau of Mine's Salt Lake Research Center (SLRC) and native strains isolated from an Alaskan mine, development of conceptual designs for in situ biological detoxification of leached heaps, and comparison of common in situ and ex situ heap detoxification processes using a cost comparison, sensitivity analysis, and Monte Carlo simulation. Microorganisms from an Alaskan mine site and SLRC were tested for cyanide degradation. Testing of samples from the Ryan Lode site indicated that several bacterial colonies could tolerate cyanide, but no degradation was found. Once degradation was confirmed in the SLRC sample, a winter survival rate test and an in situ heap detoxification test were performed. Winter survival experiments indicated approximately 5-20% of the bacterial population in heap agglomerate samples were viable after a winter and subsequent coldroom wait. In addition, bacteria colonized the agglomerate where nutrients were available. During August 1993, a 250 ton test heap was constructed on a heap that was undergoing detoxification using the INCO air-SO$\sb2$ process. The test heap was inoculated with bacteria in October 1993 and September 1994. Unfortunately, the test was terminated at an early stage, limiting the conclusions. The detoxification processes chosen for comparison were in situ biological, peroxide, and chlorination, and ex situ biological, INCO air-SO$\sb2,$ peroxide, and chlorination. To compare the costs, a hypothetical heap of 1 million tons was used. In situ biological detoxification had a cost of $0.41 per ton of ore treated, followed by ex situ biological detoxification, with a cost of \$0.92 per ton. The remaining methods ranged from $1.05 to \$1.35 per ton. The biological detoxification methods were most sensitive to the rinsing rate, labor costs, and capital costs. The chemical detoxification methods were most sensitive to oxidant cost, oxidant to cyanide ratio, and starting cyanide concentration. For the Monte Carlo simulation, in situ biological detoxification had a cost of $0.63 per ton treated, followed by in situ peroxide with a cost of \$1.09 per ton. The remaining methods ranged from $1.11 to \$1.45 per ton.
    • Biological impacts and recovery from marine disposal of metal mining waste

      Kline, Edward R. (1998)
      Waste from coastal, metal mining operations may be disposed of in the ocean. Studies were conducted using tailings and wastewater (effluent) from a proposed gold mine that is located near Juneau, Alaska, USA. The ability of invertebrates to colonize tailings after obliteration by submarine tailings disposal (STD) was assessed through a field experiment. Trays of tailings and reference sediment were placed on the sea floor and retrieved over a 22 month period. The taxonomic composition, abundance, and biomass of invertebrates that colonized tailings and reference sediment were similar. Therefore, recolonization of invertebrates after obliteration by STD should not be inhibited by the presence of these tailings as a bottom substrate. In a laboratory study, the toxicity of effluent from the milling process was compared for early life stage fish and crustaceans. Common reference species and species that are indigenous to southern Alaska were exposed to effluent. The relationship between effluent concentration and organism response was established for immobilization, paralysis, and death. For each response, the sensitivity of the reference species bracketed that of the indigenous species. An overall ranking of species sensitivity could not be made because it depended on the response that was compared. The source of effluent toxicity was determined for one of the reference species, a crustacean. A simulated effluent was created to duplicate the ionic composition of the actual effluent. Toxicity was compared in effluent, effluent with increased salinity, simulated effluent, and solutions with adjusted concentrations of ions. Calcium was in excess in the effluent, relative to seawater, and was isolated as the source of toxicity. Sodium deficiency in the effluent, relative to seawater, reduced calcium toxicity.
    • The Rampart, Manley Hot Springs, And Fort Gibbon Mining Districts Of Alaska.

      L'Ecuyer, Rosalie E.; Schuldiner, Michael (1995)
      This thesis on the Rampart, Manley Hot Springs, and Fort Gibbon mining districts of Alaska provides the first comprehensive public history of prospecting and mining activity in these three districts within the gold belt of Interior Alaska. Spanning almost one hundred years, the history begins in 1894 and extracts material from early recorders' books, old newspapers, correspondence of miners whose dreams drew them to the gold fields, and U.S. Geological Survey reports which analyzed Alaska's natural resources and mining economy. It surveys mining development from stampedes during the boom years of the turn-into-the-twentieth-century through periods of decline and on into the modern, mechanized, open-pit operations near the beginning of the twenty-first century. It concludes with an extensive annotated bibliography designed to assist other researchers in finding specialized, in-depth information about the three districts. <p>