Ettringite formation in lime-remediated mine tailings: I. Thermodynamic modeling


The optimal geochemical parameters required to form ettrin-gite in a lime-remediated site have been investigated with the use of thermodynamic modelling. The speciation of sulphate and 10 metals analyzed in samples of a mine tailing from northern Quebec was calculated with a computer model. The model also includes calcium, which would result from the addition of lime to the system. Two speciation calculations were done. The first one is a hypothetical speciation before the onset of precipitation and was used to devise the stability fields of minerals susceptible of forming in high pHs. The stability fields were determined by building activity ratio diagrams with sulphate, aluminum and calcium species concentrations for pHs ranging from 4 to 14. The investigation was carried out for a 25°C solution with an ionic strength less than 0.12. Thermodynamics predict that an optimal stability field for ettringite in the mine tailing samples containing 1&3 mol/L ofSO42, 102 mol/L of Al(OH)4 requires at least 102 mol/L of Ca*2 and a pH larger than 11.6. The sulphate contents of the mine tailing samples, however, limit the precipitation of ettringite and monosulphate could be an end-precipitate. The second speciation is in equilibrium with precipitates and provides information on the speciation of the residual metals. If ettringite could be precipitated as a stable form, it could serve as a sorptive agent for residual metals, and, due to its binding properties, consolidate tailings.
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Summary: The On-Stream Analyzer has proven, and is still proving to be, an extremely valuable tool for the control of flotation circuits. This paper examines the possibility of going further in the utilization of the analyzer results by using a real-time material balance program to calculate the mass flow rates within the streams of a circuit for process control, analysis and optimization as well as for the detection of sensor malfunction. The material balance algorithm improves measurements and give...
Publication: CIM Bulletin
Author(s): C. Bazin, A.R. Trusiak, D. Hodouin
Issue: 995
Volume: 88
Year: 1995
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Summary: Line Creek Resources Ltd. produces three million clean tonnes per year of metallurgical and thermal coals for the international market. The mining operation, which is located in the mountains of southeastern British Columbia, produces coal from four pits by conventional truck and shovel methods.
The South Pit, which has been in operation since 1982, has a benched highwall 490 m in height. Shallow dipping coal seams at the base of the syncline formation will be exposed in the highwall over the...
Publication: CIM Bulletin
Author(s): R. Williams
Issue: 995
Volume: 88
Year: 1995
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Summary: The potential use of industrial and municipal waste glass as a partial pozzolanic replacement for Normal Portland cement in mine backfill has been investigated. Considerable quantities of glass are currently discarded into landfill sites at high cost to municipal and industrial users with no foreseeable environmental benefits being gained by such disposal. This research study was undertaken to assess the viability of using ground waste glass materials as partial binder replacement of Portland...
Publication: CIM Bulletin
Author(s): J.F. Archibald, D.O. DeGagne, P. Lausch, E.M. De Souza
Issue: 995
Volume: 88
Year: 1995
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Summary: Garnet occurs in schists and gneisses in all provinces of Canada, but mainly in Quebec and Ontario. There is currently a renewed interest in exploration for economic sources of garnet for abrasive applications because of the inherent dangers from exposure to ground silica from sandblasting operations.
High-quality garnet is used for lapping and grinding of glass and ceramics; for coated and bonded products such as sandpaper and cloth; and abrasive wheels for grinding and finishing various...
Publication: CIM Bulletin
Author(s): P.R.A. Andrews
Issue: 995
Volume: 88
Year: 1995
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Summary: Acid mine drainage (AMD) research under the MEND program has been ongoing since 1988 at the Heath Steele Mines waste rock piles including sulphide material, outside Newcastle, NB. In 1989 approximately 10,000 mt of waste rock was placed on a prepared sand base with an underlying impermeable membrane. The waste rock pile was heavily instrumented for measuring oxygen concentrations and temperatures. In September 1991, a composite soil cover designed for the Heath Steele climatic conditions,...
Publication: CIM Bulletin
Author(s): Alan V. Bell, Mike D. Riley, Ernest K. Yanful
Issue: 995
Volume: 88
Year: 1995
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Summary: Autogenous grinding is used quite frequently for mineral comminution as a result of its lower capital and operating costs. However, it is more difficult to control than conventional grinding, particularly when the autogenous or semiautogenous mill is the only comminution stage (i.e. no secondary grinding is available). Analysis of the control strategy used then becomes extremely important, a task that is greatly simplified by the use of an empirical dynamic simulator.
This paper presents the...
Publication: CIM Bulletin
Author(s): J. Valenzuela, R. del Villar, M. Bourassa, S. StArnaud
Issue: 995
Volume: 88
Year: 1995
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