Kinetic Testing and Sorption Studies by Modified Weathering Cells to Characterize the Potential to Generate Contaminated Neutral Drainage

Plante, Benoît; Benzaazoua, Mostafa; Bussière, Bruno

doi:10.1007/s10230-010-0131-3

Cited by 36 publications

(12 citation statements)

References 34 publications

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“…Moreover, some Fe, Al, and Mn were still present in the exchangeable/carbonate fraction and Mn also in the water-soluble phase after the experiment. In agreement with our observation regarding the importance of exchangeable fraction for divalent metals, sorption processes have been shown to be particularly important for metal release from waste rock with low acid-producing potential, with partially oxidized waste generating Ni at much higher rates than fresh waste rock samples (Plante et al 2011). Based on the release rates observed under limited oxygen conditions in this study, it can be roughly estimated that ca.…”

Section: Resultssupporting

confidence: 92%

Impact of declining oxygen conditions on metal(loid) release from partially oxidized waste rock

Kaasalainen

Lundberg

Aiglsperger

et al. 2019

Environ Sci Pollut Res

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The best available technology for preventing the formation of acid drainage water from the sulfidic waste rock at mine closure aims to limit the oxygen access to the waste. There is, however, a concern that contaminants associated with secondary minerals become remobilized due to changing environmental conditions. Metal(loid) mobility from partially oxidized sulfidic waste rock under declining and limited oxygen conditions was studied in unsaturated column experiments. The concentrations of sulfate and metal(loid)s peaked coincidently with declining oxygen conditions from 100 to < 5 sat-% and to a lesser extent following a further decrease in the oxygen level during the experiment. However, the peak concentrations only lasted for a short time and were lower or in the similar concentration range as in the leachate from a reference column leached under atmospheric conditions. Despite the acid pH (~ 3), the overall quality of the leachate formed under limited oxygen conditions clearly improved compared with atmospheric conditions. In particular, the release of As was two orders of magnitude lower, while cationic metals such as Fe, Cu, Mn, and Zn also decreased, although to a lesser extent. Decreased sulfide oxidation is considered the primary reason for the improved water quality under limited oxygen conditions. Another reason may be the immobility of Fe with the incorporation of metal(loid)s in Fe(III) minerals, in contrast to the expected mobilization of Fe. The peaking metal(loid) concentrations are probably due to remobilization from solid Fe(III)-sulfate phases, while the relatively high concentrations of Al, Mn, and Zn under limited oxygen conditions were due to release from the adsorbed/exchangeable fraction. Despite the peaking metal(loid) concentrations during declining oxygen conditions, it is clear that the primary remediation goal is to prevent further sulfide oxidation.

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Section: Resultssupporting

confidence: 92%

Impact of declining oxygen conditions on metal(loid) release from partially oxidized waste rock

Kaasalainen

Lundberg

Aiglsperger

et al. 2019

Environ Sci Pollut Res

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“…The relatively small amounts of sulfides contained in the hemoilmenite waste rock (mainly pyrite) can be oxidized by water and air. The reactions can then produce contaminated neutral drainage, which may be responsible for occasional nickel leaching in the drainage water around the base of the waste rock piles (Bussière et al, 2015;Plante et al, 2011aPlante et al, , 2011bPlante et al, , 2014).…”

Section: Site Descriptionmentioning

confidence: 99%

Three‐Dimensional Time‐Lapse Geoelectrical Monitoring of Water Infiltration in an Experimental Mine Waste Rock Pile

Dimech

Chouteau

Aubertin

et al. 2019

Vadose Zone Journal

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Core Ideas 3D time‐lapse ERT is used to monitor water infiltration for mining environmental issues. Geoelectrical images provide information where no hydrogeological data is available. Water resistivity must be taken into account to understand bulk resistivity variations. Electrical resistivity of water is used as a tracer to reconstruct water infiltration. Infiltration model integrating both hydrogeological and geophysical data is proposed. Open‐pit mines often generate large quantities of waste rocks that are usually stored in waste rock piles (WRPs). When the waste rocks contain reactive minerals (mainly sulfides), water and air circulation can lead to the generation of contaminated drainage. An experimental WRP was built at the Lac Tio mine (Canada) to validate a new disposal method that aims to limit water infiltration into reactive waste rocks. More specifically, a flow control layer was placed on top of the pile, which represents a typical bench level, to divert water toward the outer edge. Hydrogeological sensors and geophysical electrodes were installed for monitoring moisture distribution in the pile during infiltration events. A three‐dimensional (3D) time‐lapse hydrogeophysical monitoring program was conducted to assess water infiltration and movement. Readings from the 192 circular electrodes buried in the WRP were used to reconstruct the 3D bulk electrical resistivity (ER) variations over time. A significant effort was devoted to assessing the spatiotemporal evolution of water ER because the bulk ER is strongly affected by water quality (and content). The water ER was used as a tracer to monitor the infiltration and flow of resistive and conductive waters. The results indicate that the inclined surface layer efficiently diverts a large part of the added water away from the core of the pile. Local and global models of water infiltration explaining both bulk and water ER variations are proposed. The results shown here are consistent with hydrogeological data and provide additional insights to characterize the behavior of the pile.

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“…The geochemical behavior of five ores was evaluated using modified weathering cell tests. These weathering cells are small-scale humidity cells that render similar results for the rates of reactions [35][36][37]. A 100 mm Büchner funnel with a 0.45 µm glass-fiber filter is held with 67 g of material.…”

Section: Geochemical Testingmentioning

confidence: 99%

Environmental Impact of Mine Exploitation: An Early Predictive Methodology Based on Ore Mineralogy and Contaminant Speciation

et al. 2019

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Mining wastes containing sulfide minerals can generate contaminated waters as acid mine drainage (AMD) and contaminated neutral drainage (CND). This occurs when such minerals are exposed to oxygen and water. Nowadays, mineralogical work—when it is done—is independently and differentially done according to the needs of the exploration, geotechnics, metallurgy or environment department, at different stages in the mine development process. Moreover, environmental impact assessments (EIA) are realized late in the process and rarely contain pertinent mineralogical characterization on ores and wastes, depending on countries’ regulations. Contaminant-bearing minerals are often not detected at an early stage of the mine life cycle and environmental problems could occur during production or once the mine has come to the end of its productive life. This work puts forward a more reliable methodology, based on mineralogical characterization of the ore at the exploration stages, which, in turn, will be useful for each stage of the mining project and limit the unforeseen environmental or metallurgical issues. Three polymetallic sulfide ores and seven gold deposits from various origins around the world were studied. Crushed ore samples representing feed ore of advanced projects and of production mines were used to validate the methodology with realistic cases. The mineralogical methodology consisted in chemical assays and XRD, optical microscopy, SEM and EPMA were done. Five of the ores were also submitted to geochemical tests to compare mineralogical prediction results with their experimental leaching behavior. Major, minor, and trace minerals were identified, quantified, and the bearing minerals were examined for the polluting elements (and valuables). The main conclusion is that detailed mineralogical work can avert redundant work, save time and money, and allow detection of the problems at the beginning of the mine development phase, improving waste management and closure planning.

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Kinetic Testing and Sorption Studies by Modified Weathering Cells to Characterize the Potential to Generate Contaminated Neutral Drainage

Cited by 36 publications

References 34 publications

Impact of declining oxygen conditions on metal(loid) release from partially oxidized waste rock

Impact of declining oxygen conditions on metal(loid) release from partially oxidized waste rock

Three‐Dimensional Time‐Lapse Geoelectrical Monitoring of Water Infiltration in an Experimental Mine Waste Rock Pile

Environmental Impact of Mine Exploitation: An Early Predictive Methodology Based on Ore Mineralogy and Contaminant Speciation

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