Revegetation is employed to mitigate the spread of mine tailings in the environment by ameliorating tailings with organics to promote plant cover. Revegetation has proven to be successful in establishing plant cover, but the long-term effects are largely unknown. A field study was conducted to evaluate the success of four artificially revegetated tailings from Manitoba by comparing plant cover and diversity. Central Manitoba, Flin Flon, and Thompson had moderate cover while cover was low in Lynn Lake. All four sites had low diversity and were composed of early-successional species. The results suggest that while current revegetation methods promote plant growth on tailings, it is currently difficult to determine if and how the vegetation will progress from a grass-legume community to a boreal forest. In addition, while various amounts of effort were invested into each site, the results indicate the degree of remediation does not affect overall success.

Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2008.

Thesis (M. Environmental Science)--North-West University, Potchefstroom Campus, 2008.

Revegetation is employed to mitigate the spread of mine tailings in the environment by ameliorating tailings with organics to promote plant cover. Revegetation has proven to be successful in establishing plant cover, but the long-term effects are largely unknown. A field study was conducted to evaluate the success of four artificially revegetated tailings from Manitoba by comparing plant cover and diversity. Central Manitoba, Flin Flon, and Thompson had moderate cover while cover was low in Lynn Lake. All four sites had low diversity and were composed of early-successional species. The results suggest that while current revegetation methods promote plant growth on tailings, it is currently difficult to determine if and how the vegetation will progress from a grass-legume community to a boreal forest. In addition, while various amounts of effort were invested into each site, the results indicate the degree of remediation does not affect overall success.

Modified cellulase enzyme assay methods were developed to determine the potential of using enzyme activities to evaluate the decomposition of organic matter in carbon amended mine tailings systems. Cellulase assays are commonly performed in soil science applications, industrial production and bio-energy research to determine organic matter response to physical, chemical or temporal variation but, they have not been applied in a mine waste environment. Heavy metal content is considered to be a potential inhibitor to cellulase enzyme activity. Using samples collected from Greens Creek Mine in Juneau, Alaska, USA, the modified assay was evaluated to develop a method that provided reproducible results. It was determined that a sample mass of three grams is sufficient to provide consistent enzyme measurements. Each sample location was characterized by four replicates to ensure statistically representative data. Matrix interferences were determined to be inconsequential in this system. Despite the low organic content amended to the tailings, heavy metal content and potentially low enzyme activity, the modified enzyme assay method provided reproducible enzyme measurements. Following the development of the cellulase assays, spatial and temporal variations in cellulase enzymes were investigated from carbon amended tailings samples collected at the Greens Creek Mine. Six test cells, containing a mixture of tailings and a combination of peat, spent brewery grain and/or municipal biosolids were sampled in the fall of 2005, 2007 and 2009. Exo-(1,4)-β-D-glucanase (EC 3.2.1.91), Endo-(1,4)-β-D-glucanase (EC 3.2.1.4) and β-glucosidase (EC 3.2.1.21) enzymes were assayed from core sections at five different depths. Enzyme activities were compared to sulfate reducing and acid producing bacterial enumerations, sulfide trends and carbon content. General trends were consistent between enzyme activity and SRB enumerations. The range of total carbon values fell between 3 and 5 wt % in each test cell while the average inorganic carbon content was 3.5 wt %. The range of organic carbon content was between 0.2 and 1.2 wt %. Total, inorganic and organic carbon values were more characteristic of test cell carbon distribution. Cellulase enzyme assays provide valuable information regarding the degradation of cellulose and hemi-cellulose. This study demonstrates that enzymes can be monitored in a tailings environment and that enzyme assays conducted for monitoring purposes may be a useful practice to indicate the sustained or declining performance of organic matter in a carbon amended remedial system.

This research is a follow up to preliminary studies reported by Beier and Sego (2008) and the objective is to investigate laboratory scale dewatering of oil sands total tailings using cross flow filtration technology. A laboratory experiment was setup in Oil Sands Tailings Research Facility and tests were carried out under different operational conditions using different tailings. The experiments showed clean filtrate water generated under all test conditions. Coarser tailings and higher filter pipe porosity resulted in greater filtrate flux rate. The effect of slurry velocity, residual bitumen, and transmembrane pressure on cross flow filtration performance was also evaluated. A dimensional analysis was developed using the laboratory tests to establish the relationships between measured parameters and to assist and guide future experimental programs. / Geotechnical Engineering

This thesis explores the behaviour of metal cyanide complexes under oxidative acid conditions in ion exchange systems, with the objective of developing an ion exchange based process for the treatment of gold cyanidation tailings. The novel cyanide detoxification process developed from this study employs strong base ion exchange resins to extract cyanide from tailings. Variations in the stability of cyanide complexes are exploited to concentrate, recover, or destroy cyanide species loaded on the resin, through the use of an oxidative acid eluent containing H2O2 and H2SO4. This eluent removes all base metal cyanide complexes from strong base resins, while regenerating the resin. The spent eluent, containing the base metals recovered from the tailings, can be used as a source of such base metals. Copper can be recovered separately from other base metals if necessary. Low levels of precious metals present in the tailings are accumulated on the resin as the ion exchange bed is cycled between loading and elution stages. They can be recovered economically, so as to offset the cost of the tailings detoxification. Cyanide is initially concentrated as an alkaline solution, which can be detoxified within the process or recovered for recycling. This process was successfully tested at pilot scale by treating approximately 14,000 m3 of cyanide contaminated tailings solution, over 14 loading/elution cycles on a standard strong base ion exchange resin bed. This treatment reduced the total cyanide concentration of the contaminated solution from approximately 50 mg/L to an average of 1.5 mg/L. The reagent cost was approximately ADD 0.50 per m3 of treated liquor. When the resin was repeatedly loaded with mixed metal cyanide species and eluted with the oxidative acid eluent, a gradual deterioration of the ion exchange resin performance was noted. The reduction of net operating capacity of the columns due to resin deterioration was in the order of 1-3% per loading/elution cycle. The oxidation of resin catalysed by copper, the precipitation of metal hexacyanoferrates on the resin and the oxidation of Au(CN)2- to Au(CN)4- were identified as possible factors giving rise to the reduction of resin loading capacity.

Thesis (M.S. - Hydrology and Water Resources)--University of Arizona, 1982. / Includes bibliographical references (leaves 110-116).

Thesis (M.S.)--University of Arizona, 1982. / Abstract. Includes bibliographical references (leaves 135-139). Includes bibliographical references (leaves 175-187).

Thesis (M.S.)--University of Missouri, School of Mines and Metallurgy, 1910. / The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed March 26, 2009)