No description available.

Thesis (Ph. D.)--University of Adelaide, Dept. of Civil Engineering, 1992. / Includes bibliographical references.

The Ruttan Cu-Zn mine produced approximately 30 million tons of fine-grained tailings over 30 years. Since the closure of the mine in 2002, the tailings have been systematically dewatered through trenches which drain into Ruttan Lake and into the open pit and underground mine workings. This study evaluated the evolution of the tailings of Cell 3, which was underwater in 2002, and Cell 2, which was already dry and oxidized. Dewatering the submerged tailings in Cell 3 resulted in measureable changes in acidification in pore and shallow groundwater from rapid oxidation of very fine grained sulphides. Depth profiles of the concentration of metals in dissolved and solid fractions, when compared to other studies, suggest that the tailings in Cell 2 and Cell 3 are in an early stage of oxidation and that these tailings will produce low pH, metal laden water for years. / February 2009

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1921. / The entire thesis text is included in file. Typescript. Illustrated by authors. Title from title screen of thesis/dissertation PDF file (viewed February 10, 2010)

The Deilmann Tailings Management Facility (DTMF) at Key Lake in northern Saskatchewan, Canada, is an active deposition site for uranium tailings and it has been in operation since 1996. In terms of geochemical stability of the tailings, a ferrihydrite secondary phase is utilized for the sequestration of contaminants, such as As, Ni, Mo, and Se, under alkaline and highly oxic conditions. Arsenic is highly abundant in the DTMF tailings and the principal environmental concern is the possibility for leaching of ferrihydrite-attached As into the surrounding environment. Microorganisms can proliferate in a broad range of habitats and their activities are key factors in determining fate and transport of contaminants in various environments. This thesis attempts to obtain insights into the biogeochemical processes that may occur during the early phase of the DTMF’s history that could potentially become significant over extended periods of time that run from 100’s to 1000’s of years. Hence, a primary focus was to characterize microbial diversity and extrapolate their potential functional roles as well as their potential to chemically alter the Eh and ferrihydrite, which are the primary controlling conditions within the DTMF tailings and in the mineral secondary phase, respectively. To achieve these goals, two molecular techniques (clone library construction and Ion Torrent sequencing), a range of conventional culture-based techniques, metabolic assays addressing metabolic transformation and resistance to metals/metalloids, microscopic technique (Confocal Laser Scanning Microscope), spectroscopic analyses (Scanning Transmission X-ray Microscope) and bench-scale microcosm assays were carried out. Culture-dependent and -independent methods revealed that the most prevalent microbial groups in the water column, tailings mass and at the tailings-water interface affiliated into phyla (e.g., Proteobacteria, Actinobacteria, Firmicutes and Bacteriodetes) that have previously been detected at uranium-, heavy metal- and complex hydrocarbon-contaminated sites. Phylotypes closely related to well-characterized sulfate-, thiosulfate- and iron-reducing bacteria (e.g., Desulfosporosinus, Dethiobacter, Geoalkalibacter, Ralstonia, Georgfuchsia) were also detected at low frequency, with the exception of the tailings-water interface where sequences closely related to Desulfosporosinus were abundant. The readily culturable heterotrophs (e.g., Pseudomonas, Arthrobacter, Massilia, Hydrogenophaga, Polaromonas, Bacillus) retrieved from the tailings exhibited reducing/oxidizing capabilities as well as high tolerance to metal/metalloids. Bench scale microcosm assays showed that heterotrophs native to the DTMF site could not only reduce ferrihydrite but could also create highly reducing (< -300 mV) conditions within the tailings amenable to strict anaerobic bacteria such as Desulfosporosinus. STXM image analyses confirmed the presence of reduced iron in close proximity to bacterial cells in biofilm grown in situ and in microcosm tailings, strongly suggesting that ferrihydrite served as electron acceptor during microbial processes. Reduced iron detected in situ also indicated that microscale iron reduction could occur even though macroscale DTMF chemistry remained oxidizing. Overall, the nature of microbial community present in the DMTF system strongly indicated that complex hydrocarbons (e.g., kerosene) discharged into the tailings during processing could potentially support microbial processes that involve Fe and S cycling and that this process could become significant over extended period of times, contributing to arsenic escape into the environment.

No description available.

No description available.

The purpose of this thesis was to investigate the potential ability of nano-scale zerovalent iron (nZVI) to remediate multiple metal contaminants, specifically in the context of mine tailings. The project began by adopting techniques reported on by investigators researching the remediation effectiveness on metal contaminants of nZVI within the framework of civil engineering applications, such as groundwater treatment (Karabelli et al, 2008). This phase of the project saw the treatment of laboratory prepared samples of copper contaminated waters (at 10, 30, 50 and 100 ppm) by the addition of unstabilized nZVI. Results showed that all but the 100 ppm samples were effectively cleared of nearly all metal contamination following treatment additions of 1 mL nZVI to 50 mL of sample water. The second phase of the project sought to expand on this success by subjecting laboratory prepared water samples containing multiple metal contaminants to the same dose on nZVI. A collection of metal contaminants, known as the Arctic Suite, containing arsenic, cadmium, cobalt, chromium, nickel, lead and zinc, was made up as contaminated waters (at 1, 3, 5, and 10 ppm concentrations) and was tested for nZVI remediation. Results showed that only the 10 ppm samples were not effectively remediated and furthermore showed preferential treatment of arsenic, chromium and lead instead of an even distribution of treatment amongst all metal contaminants present. The final phase of the project saw the testing of contaminated waters produced from five mine tailings, acquired from separate sources, by the same dose of nZVI as in the first two phases of the project. Results showed that where contaminant metals were present some remediation effect did occur. However, an inability to produce highly contaminated leachates from the mine tailings meant that no trends in nZVI remediation effectiveness could be determined with any certainty. / Thesis (Master, Mining Engineering) -- Queen's University, 2011-09-01 11:04:28.869

No description available.

No description available.