Decontamination of Elliot Lake uranium tailings

Abstract After more than 93% of the uranium is extracted from Elliot Lake uranium ores by a sulphuric acid leaching process, the leach residue (tailings) contains small amounts of uranium and radioactive isotopes, particularly radium-226, which is the most serious health hazard. Heavy metal components and pyrite are also present, along with the gangue minerals. Currently, over 1000 acres of the Elliot Lake area are covered with these tailings, which contain over five million tons of pyrite.Because of constant oxidation of the pyrite by bacteria (thiobacillus) and the presence of moisture, pyrite slowly generates sulphuric acid, which steadily leaches the metal-bearing constituents from the tailings. The seepage-flows of the dissolved contaminants, although often quite low in volume, have an environmental impact on the Elliot Lake area. Although these seepages are treated and most of the contaminants removed and impounded, a small amount of the radioactive contaminants reaches Lake Huron via the Serpent River.This paper describes a flotation approach for treatment of the Elliot Lake uranium tailings to produce new, deconlaminated tailings practically free of pyrite, with radium, thorium and uranium contents considerably reduced. The decontaminated tailing produced, which comprises about 75% by weight of the current uranium tailings, appears to be suitable for mine backfill. Because mine backfilling normally uses about 50% of the plant tailings, the surface storage of about half of the uranium tailings, therefore, would be eliminated by this process. Mine backfilling would also increase the mine production and thus enlarge the over-all uranium resources due to recovery of the ore from pillars. The pyrite concentrate produced from the current uranium tailings would be suitable for sulphuric acid production.The possibility of uranium recovery, and disposal of radium and thorium from the concentrates produced, is now being studied at CANMET.
Keywords: Uranium tailings, Elliot Lake, Decontamination, Radioactivity, Flotation, Pyrite, Tailings disposal, Environmental control.
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Summary: Thunder Bay Terminals' plant, now in operation, cost about 70 million dollars and was completed on time and under budget. The paper is the project manager's account of this accomplishment. From site selection through feasibility, engineering and construction to realization, he emphasizes the necessary philosophies for the control of time and money. The computer as a tool is discussed, as well as techniques for procurement.
Publication: CIM Bulletin
Author(s): P. R. COOK
Keywords: Thunder Bay Terminals Ltd., Site selection, Management, Construction, Planning, Approvals, Permits, Scheduling.
Issue: 808
Volume: 72
Year: 1979
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Summary: The transportation challenge began with the need to move millions of tons of coal annually from Western Canada to Ontario. The paper will discuss the options which were available, the final mode selected and the economic trade-offs which were involved. It will outline the demands of unit train technology and the effect of transportation requirements on the other elements of the whole system.
Publication: CIM Bulletin
Author(s): R. E. LAWLESS, R. P. LANGLOIS
Keywords: Thunder Bay Terminals Ltd., Transportation, Railways, Trains, Unit Trains, Coal.
Issue: 808
Volume: 72
Year: 1979
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Summary: This paper discusses: (1) the need for Western Canadian coal in eastern Ontario Hydro plants; (2) design parameters—unit trains, year- 'round receiving from trains, and shipping (Great Lakes season); (3) equipment chosen—dumper-indexer, outhaul conveyor, yard belt, stacker, reclaimer, surge-bin feeders, shiploader, docking system and dust control; (4) foundation and soil conditions—dumper house, yard belt, surge bin and dock-piling-runway; (5) winter conditions—thaw...
Publication: CIM Bulletin
Author(s): J. CARR
Keywords: Thunder Bay Terminals Ltd., Design, Terminals, Plant design, Coal handling, Ontario Hydro, Stockpiles, Dumper houses, Car dumpers, Winter operations, Stackers, Reclaimers, Shiploaders.
Issue: 808
Volume: 72
Year: 1979
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Summary: Concern over the acid drainage and radionuclide dissolution problems associated with current uranium tailings disposal methods, as well as the lack of thorium production in Canada, has prompted investigation into new and improved methods for the extraction of uranium and thorium from their ores.One such method currently under investigation at CANMET is the high-temperature chlorination of uranium ore, for which the objective is to develop a process which is both economically viable and...
Publication: CIM Bulletin
Author(s): J. M. SKEAFF
Keywords: Extractive metallurgy, Ore processing, Chlorination, Ra-dionuclides, Pyrite, Tailings disposal, Uranium tailings, Acid drainage, Uranium extraction, Thorium extraction, Radium extraction, Elliot Lake.
Issue: 808
Volume: 72
Year: 1979
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Summary: McKellar Island, the site of the Thunder Bay Terminals coal handling facility, is situated in a low-lying delta area. The ground surface across the island, which is relatively flat at between 1 and 5 ft above lake level, is underlain sequentially by surficial peat materials, extensive lacustrine strata and glacial till deposits which overlie shale bedrock. Each of these major stratigraphic units significantly influenced the design and construction of major features of the facility.Coal is to...
Publication: CIM Bulletin
Author(s): J. L SEYCHUK, J. H. A. CROOKS
Keywords: Thunder Bay Terminals Ltd., Geotechnical engineering, McKellar Island, Terminals, Design, Construction, Geomorphology, Lacustrine deposits, Foundations, Stockpiles, Coal, Slope stability, Conveyors, Tunnels, Monitoring
Issue: 808
Volume: 72
Year: 1979
Text
Summary: Orebodies of the Renison Bell - Mt. Bischoff tinfield in Tasmania are stratabound, conformable lenses of massive cassiterite-bearing pyrrhotite, with underlying discordant, fault-fracture-controlled and more siliceous ore. The deposits occur in eugeosynclinal, trough-deposited sedimentary and mafic volcanic rocks which are stratigraphically equivalent to differentiated volcanic rocks that contain volcanogenic massive base metal sulphide deposits in a parallel arc to the east. Textures of the...
Publication: CIM Bulletin
Author(s): R. W. HUTCHINSON
Keywords: Ore deposits, Tin deposits, Tasmania, Pyrrhotite, Cassiterite, Sulphides, Massive sulphides, Renison Bell Mine, Exhalative origins, Volcanogenic rocks.
Issue: 808
Volume: 72
Year: 1979
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