• Applicability of siberian placer mining technology to Alaska

      Skudrzyk, F.J.; Barker, J.C.; Walsh, D.E.; MacDonald, Rocky (University of Alaska Mineral Industry Research Laboratory, 1991)
      The result of Perestroyka and Glasnost has been an awakening of potential for cooperation between East and West. Nowhere has that been better demonstrated than between Alaska and Magadan Province, USSR. This report summarizes a one year effort financed by ASTF, with participation from several technical organizations, to establish contacts with the Siberian placer mining industry. The purpose of the project was to provide initial assessment of the Soviet technology for placer mining in permafrost. A ten day trip to Magadan province by an ASTF team and a similar length visit to Alaska by the Soviet mining group representing the All Union Scientific and Research Institute of Gold and Rare Metals, (VNII-I), Magadan are described. The report also reviews translated data on mining in permafrost and describes surface and underground placer mining technology developed by the Soviets. The report also lists relevant publications on Soviet mining research and state of the art Soviet mining technology and expertise.
    • Application of hydrocyclones for recovery of fine gold from placer material

      Rao, P.D.; Wolff, E.N.; Maneval, D.R. (University of Alaska Mineral Industry Research Laboratory, 1982)
      Alaska and other gold areas have seen a sharp resurgence of placer mining in the last few years. Mines using sluice boxes usually recover gold down to 100 mesh, but recovery of gold finer than this size is a function of particle shape factor, sluice box design and operating parameters. It is felt that a concentrating device is needed to recover gold finer than 100 mesh that may not be recoverable in a sluice box. The device should be capable of processing a large volume of water and solids discharged from the sluice-box. Compound water cyclones, successfully used in the coal processing industry, seem to offer solutions. A system using these devices could recover a concentrate which would be one twenty fifth the size of the original solids in a two stage process. It is not intended to produce a finished product with cyclones, but to reduce bulk so that the reduced concentrate, free of slimes, could further be treated by flotation, gravity methods, or cyanidation to isolate the gold. This report addresses only the application of hydrocyclones for concentrating gold from placer material.
    • Application of hydrocyclones for the treatment of wastewater in gold placer mining

      Lin, H.K. (University of Alaska Mineral Industry Research Laboratory, 1980)
      This is a report on experimental application of hydrocyclones for the wastewater treatment in placer mining, with emphasis on their use in combination with a kind of large molecular weight flocculant. The simultaneous flocculating and clarifying of placer mining effluents was tested and evaluated.
    • The combined use of a sand screw, hydrocyclones, and gel-logs to treat placer mine process water

      Chuang, YeKang (University of Alaska Mineral Industry Research Laboratory, 1988)
      This study describes a low-maintenance tailings treatment system for placer mines. A sand screw and two 20 inch hydrocyclones were used to remove gravel, sand and silt from a sluice box discharge. Gel-logs were introduced subsequent to the main settling pond to reduce the suspended solids. Results drawn from a two year study at a placer mine in interior Alaska indicated that: (1) Most of the plus 50 mm particles can be removed from the sluice tailings by the combination of a sand screw and 20 inch hydrocyclones, (2) When using the hydrocyclone overflow, without further cleaning, in recycle operation, the performance of the sand screw and hydrocyclones change due to the build up of fine particles. (3) In laboratory testing cationic type gel-logs proved to be effective in reducing the turbidity of settling pond water from 4,000 NTU to 80 NTU. However, at the mine this test result could not be duplicated even though 14 logs were applied to treat 25% (c 500gpm) of the pond overflow. The cost of installation and operation of the sand screw and hydrocyclone system was about 11% of the total operational cost of the mine in 1986.
    • The effects of placer mining on the environment in Central Alaska

      Wolff, E.N.; Thomas, B (University of Alaska Mineral Industry Research Laboratory, 1982)
      Within the Tolovana Mining District, as a result of placer mining, 800 acres of land have been disturbed (0.25% of the land area) and 4 million cubic yards of much have been transported down the Tolovana River through the subsiding Minto Flats. This has increased the rate of sedimentation of the lakes adjacent to the Tolovana River. Mine tailings are about 50% revegetated by natural species. Approximately 60 million cubic yards of muck must be removed to mine the Livengood deposits. A large area of settling ponds will be needed if the deposit is stripped by hydraulic means, or a large area for stacking overburden if mechanical stripping is required. The Crooked Creek area, mined for 80 years has 1,900 acres disturbed (0.7% of the land area) and 200,000 cubic yards of much has been stripped. No correlation is apparent between mining and the non-anadromous fish population, although sport fishing is considered by some to be not as good as a result of mining. Portions of the stream system observed to be impacted with mud showed evidence of having been periodically flushed out. Slave analysis and trace element analysis were applied in an attempt to trace sediments back to their sources, but were not successful. Mining is the pioneer industry around which much of the State of Alaska developed. The transportation network required by the mining industry benefits sportsmen, the tour industry, and directly increases the value of adjacent land. The profit from mining brought much of the early population to the state, and will be a steady source of revenue in years to come.
    • The Effects of Surface Disturbances on the Leaching of Heavy Metals

      Dixson, David P.; Brown, Edward J. (University of Alaska, Institute of Water Resources, 1987-10)
      The harmful effects of heavy metal contamination of surface waters impacted by gold mining activity are well documented. An examination was conducted on the effects of surface disturbances in Wade Creek on the concentrations of heavy metals in solution, and whether Thiobacillus ferrooxidans, a bacteria found in heavy metal contaminated drainages from placer mines, is found in the drainage. Thiobacillus ferrooxidans was not detected in this particular setting. The effects of mining activity and relandscaping of stockpiled tailings showed in a short distance, a net increase of dissolved arsenic, copper, zinc, and iron. However, the long distance impact of dissolved metals was minimal. Generally, it seems that the dampening of the total suspended solids had a direct effect on the removal of metals dissolved in solution.
    • Third annual conference on Alaskan placer mining

      Campbell, B.W. (University of Alaska Mineral Industry Research Laboratory, 1981)
      This Conference has been designed to present pertinent information on the foregoing facets of Placer Mining for the benefit of the industry; to allow discussion with fellow miners, and to permit sharing experience so that each may benefit i n conducting his own operation.
    • The use of flocculants to control turbidity in placer mining effluents

      Shen, Yun-Hwei (University of Alaska Mineral Industry Research Laboratory, 1987)
      In this study, two placer mine discharge waters of different characteristics were tested in order to determine the applicability of organic polymer flocculants to achieve reduced levels of turbidity. The water samples from both mines were characterized both as to their chemical and physical properties. The jar test was employed to establish the optimum operation conditions of the flocculation process. The best results were obtained employing a cationic polymer Superfloc 340 produced by American Cyanamid Company. The optimum dosage for water samples from both mines were 15 ppm and 40 ppm respectively. Optimum agitation time was within the range of 3 to 9 minutes depending on the agitation rate and the pulp density of water sample. The utilization of settling ponds, in conjunction with flocculation is believed to be a practical method to control the turbidity level of placer mine discharge water.
    • Using polyethylene as a coagulant for reducing turbidity from placer mining discharge

      Fan, Ray-Her (University of Alaska Mineral Industry Research Laboratory, 1987)
      Placer gold mining locations on Gilmore and Crooked Creeks in the Fairbanks and Central/Circle, Alaska areas, respectively, were chosen as study sites for evaluation of a unique water treatment process. The physical and chemical impacts on water quality by placer mining were investigated by measuring the pH value, turbidity, and solids content of the slurry samples. Sedimentation tests, zeta potential measurements, and particle size distribution analyses were conducted as well. Also analyzed were mineralogical and chemical composition of the suspended ultrafine particles. Flocculation tests using polyethylene oxide (PEO) with adjunct additives were conducted in the laboratory. Variable parameters such as mixing speed and time, reagent dosages, pH values, as well as synergistic factors were studied. Economic factors and chemical consumption were evaluated and a field treatment plant was designed and proposed.