Minéralisation du carbone dans une halde à résidus miniers ultramafiques : une approche pétrophysique et géophysique

Authors: Horswill, Micha
Advisor: Dupuis, J. Christian; Beaudoin, Georges
Abstract: When exposed to rainwater and carbon dioxide, magnesium rich mining wastes spontaneuously capture CO2 through carbon mineralization. Extensively studied in the laboratory, this reaction is still ill-understood at the scale of industrial mining waste pile. In order to document the spatial distribution of carbon mineralization and identify its petrophysical signature, two holes were drilled at the center of a tailings pile in Thetford Mines, Qc, Canada. The physical properties of the mining residues were evaluated from drill core samples. The petrophysical signature of zones favorable for carbon mineralization was investigated using electrical resistivity, magnetic susceptibility and borehole radar data. These data showed that the variations of air and water permeability cause alterations that are related to carbon mineralization not being uniform throughout mining wastes. Preferential air-ow can enhance carbonation at depth by increasing the amount of CO2 that reaches the interior of the waste pile. The growth of carbonates which are resistive isolate the grains and restrict water ingress and contributes to the observed increases in electrical resistivity. The decrease in magnetic susceptibility during carbonation is attributed to the partial destruction of magnetite. The iron released during the alteration of magnetite and serpentine is accumulated on the grain surface and feeds the formation of goethite. The level of destruction of the magnetite provides insights into the level of alteration caused by in-situ weathering of the mining wastes. Therefore, an increase in electrical resistivity accompanied by a decrease in magnetic susceptibility can serve as an indicator for zones with favorable conditions for the carbon mineralization reactions. These results represent the rst step towards quantifying the volume of CO2 captured in these mining residues and track the progress of the reaction with time.
Document Type: Mémoire de maîtrise
Issue Date: 2018
Open Access Date: 19 September 2018
Permalink: http://hdl.handle.net/20.500.11794/31249
Grantor: Université Laval
Collection:Thèses et mémoires

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