Characterization of leached layers on olivine and pyroxenes using high-resolution XPS and density functional calculations

Zakaznova-Herzog, V.P.; Nesbitt, H.W.; Bancroft, G.M.; Tse, John S.

doi:10.1016/j.gca.2007.09.031

Cited by 68 publications

(38 citation statements)

References 53 publications

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“…and Mg 2? in the enstatite structure, followed by the relatively slow detachment of silica from partially liberated tetrahedral chains (Oelkers and Schott 2001;Oelkers et al 2009;Zakaznova-Herzog et al 2008). Enstatite is believed to exchange about 3.1 hydrogen atoms for each Mg at the reacting sites, following Eq.…”

Section: Plagioclase Reactivitymentioning

confidence: 99%

Predicting Geochemical Behaviour of Waste Rock with Low Acid Generating Potential Using Laboratory Kinetic Tests

2010

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Prediction of contaminated neutral drainage using laboratory kinetic tests designed for acid mine drainage prediction is challenging because of the low metal concentrations generated by low sulfide oxidation rates. Fresh and weathered samples from the Tio mine waste rock piles were submitted to humidity cell tests. The waste rocks were demonstrated to be non-acid generating in the long term, as interpreted by conservative oxidation-neutralization curves. The results demonstrate that even though the main neutralizing minerals react differently after 25 years of natural weathering (with regard to Ca, Mg, Al, and Si release), the response of the fresh waste rocks during humidity cell leaching was very similar to those of the weathered waste rocks, when considering all the elements related to silicate dissolution, including those implicated in secondary phase precipitation. However, Ni generation was greater in the weathered waste rocks even though sulfide oxidation rates were similar, as Ni sorption properties reach saturation. Although the Ni concentrations from the leachates of humidity cell tests remain below regulated values, they are bound to increase with continued weathering if no preventive or control measures are undertaken at the site.

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Section: Plagioclase Reactivitymentioning

confidence: 99%

Predicting Geochemical Behaviour of Waste Rock with Low Acid Generating Potential Using Laboratory Kinetic Tests

2010

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“…Mg was observed to be preferentially released relative to Si from the forsterite surface during the initial stages of its dissolution at acidic pH (Seyama et al, 1996;Schott, 2000a, 2000b;Zakaznova-Herzog et al 2008;Oelkers et al, 2009;King et al, 2011). This behavior can result in the formation of a Si-enriched surface layer that may polymerize and influence dissolution rates; Daval et al (2011) reported that forsterite dissolution rates decrease as acidic CO 2 -rich fluids become saturated with respect to amorphous silica, similar to the behavior previously observed for multi-component mineral and glass dissolution (e.g.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, the dissolving olivine surface can become covered by secondary minerals and/or bacteria (c.f. Giammar et al, 2005;Zakaznova-Herzog et al 2008;Olssen et al, 2012;Wang and Giammar, 2012;Hövelmann et al, 2013;Saldi et al, 2013). The degree to which secondary surface precipitates affect the dissolution rates of the primary mineral appears to depend on the structural match between the two minerals and the presence of interconnected porous pathways in the secondary phases (Hodson, 2003;Cubillas et al, 2005;Putnis, 2009;Stockmann, 2011Stockmann, , 2013Saldi et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

The efficient long-term inhibition of forsterite dissolution by common soil bacteria and fungi at Earth surface conditions

Oelkers

Benning

Lutz

et al. 2015

Geochimica et Cosmochimica Acta

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“…Given the high reactivity of olivine, the surface chemistry and dissolution kinetics have been studied under a broad range of experimental conditions, including closedsystem (Giammar et al, 2005;King et al, 2010;Daval et al, 2011) and well-mixed flow-through dissolution experiments on powdered olivine samples (Pokrovsky and Schott, 2000b;Oelkers, 2001), as well as single crystals (Jarvis et al, 2009;Saldi et al, 2013). Characterization of the reaction products has also included a range of techniques, such as X-ray photoelectron spectroscopy (Pokrovsky and Schott, 2000a;Zakaznova-Herzog et al, 2008;Olsson et al, 2012), infrared spectroscopy (Pokrovsky and Schott, 2000a;Giammar et al, 2005;Loring et al, 2011), transmission electron microscopy (Bearat et al, 2006;Daval et al, 2011) and atomic force microscopy (King et al, 2014). Despite the range of studies focused on olivine reactivity in the presence of aqueous solutions, predictive models for olivine dissolution are subject to large uncertainties (Daval et al, 2011;Rimstidt et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

A spatially resolved surface kinetic model for forsterite dissolution

Maher

Johnson

Jackson

et al. 2016

Geochimica et Cosmochimica Acta

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The development of complex alteration layers on silicate mineral surfaces undergoing dissolution is a widely observed phenomenon. Given the complexity of these layers, most kinetic models used to predict rates of mineral-fluid interactions do not explicitly consider their formation. As a result, the relationship between the development of the altered layers and the final dissolution rate is poorly understood. To improve our understanding of the relationship between the alteration layer and the dissolution rate, we developed a spatially resolved surface kinetic model for olivine dissolution and applied it to a series of closed-system experiments consisting of three-phases (water (±NaCl), olivine, and supercritical CO 2) at conditions relevant to in situ mineral carbonation (i.e. 60 °C, 100 bar CO 2). We also measured the corresponding d 26/24 Mg of the dissolved Mg during early stages of dissolution. Analysis of the solid reaction products indicates the formation of Mg-depleted layers on the olivine surface as quickly as 2 days after the experiment was started and before the bulk solution reached saturation with respect to amorphous silica. The d 26/24 Mg of the dissolved Mg decreased by approximately 0.4‰ in the first stages of the experiment and then approached the value of the initial olivine (À0.35‰) as the steady-state dissolution rate was approached. We attribute the preferential release of 24 Mg to a kinetic effect associated with the formation of a Mg-depleted layer that develops as protons exchange for Mg 2+. We used experimental data to calibrate a surface kinetic model for olivine dissolution that includes crystalline olivine, a distinct ''active layer" from which Mg can be preferentially removed, and secondary amorphous silica precipitation. By coupling the spatial arrangement of ions with the kinetics, this model is able to reproduce both the early and steady-state long-term dissolution rates, and the kinetic isotope fractionation. In the early stages of olivine dissolution the overall dissolution rate is controlled by exchange of protons for Mg, while the steady-state dissolution rate is controlled by the net removal of both Mg and Si from the active layer. Modeling results further indicate the importance of the spatial coupling of individual reactions that occur during olivine dissolution. The inclusion of Mg isotopes in this study demonstrates the utility of using isotopic variations to constrain interfacial mass transfer processes. Alternative kinetic frameworks, such as the one presented here, may provide new approaches for modeling fluid-rock interactions.

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Characterization of leached layers on olivine and pyroxenes using high-resolution XPS and density functional calculations

Cited by 68 publications

References 53 publications

Predicting Geochemical Behaviour of Waste Rock with Low Acid Generating Potential Using Laboratory Kinetic Tests

Predicting Geochemical Behaviour of Waste Rock with Low Acid Generating Potential Using Laboratory Kinetic Tests

The efficient long-term inhibition of forsterite dissolution by common soil bacteria and fungi at Earth surface conditions

A spatially resolved surface kinetic model for forsterite dissolution

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