The kinetics of the reaction CO2 + H2O → H+ + HCO3− as one of the rate limiting steps for the dissolution of calcite in the system H2OCO2CaCO3

Dreybrodt, Wolfgang; Lauckner, J.; Liu, Zaihua; Svensson, U.; Bühmann, Dieter

doi:10.1016/0016-7037(96)00181-0

Cited by 183 publications

(94 citation statements)

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“…La dissolution ou la cimentation partielle des minéraux de remplissage à l'intérieur des plans des fractures s'avère y jouer un rôle primordial. En effet, Dyke (1995) (Sjoberg et Richard, 1984), le volume d'eau écoulé et la surface de contact de la calcite (Plummer et Wigley, 1976;Dreybrodt et al, 1996), et la température (Golubev et Garibyants, 1971;Sjoberg et Richard, 1984). Par ailleurs, la présence de certains ions, tels que les métaux, peut ralentir les réactions de dissolution de la calcite (Plummer et Wigley, 1976).…”

Section: Processus Hydrochimiquesunclassified

Étude des processus chimio-hydro-mécaniques dans un massif rocheux fracturé perturbé par une exploitation minière :

Benlahcen¹

2003

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This study on the chemical, hydraulic and mechanical processes and their coupling, was conducted at the Bouchard-Hébert Mine, located in the Abitibi Mining District in Québec, Canada. In this mine environment, the acidic water migrating from the old mine workings to the new ones, in combination with the perturbed geomechanical stress field caused by the excavations, affect the rock mass permeability. Both field work and laboratory experiments were conducted in order to investigate these processes, particularly in the rock mass portion located between the two mine workings (drift at level 6A).Results of discontinuity mapping show that at the western part of the drift at level 6A (from 10600E to 10900E), the rock mass contains two sets of fractures: one set is subhorizontal (dip between 0° and 30°) with a trace length between 1 and 1.5 m, and the other set is subvertical (dip between 75° and 90°). This subvertical set is divided into two groups depending on their trace length: one group includes fractures with a trace length between 0.5 and 2 m, and the second group comprises fractures with a trace length between 3 and 3.5 m. The fracture density of these two sets of fractures varies from 1 to 6 m" 1 and their veins are 2 mm in width. At the eastern part of the drift at level 6A (from 10900E to 11200E), the rock mass contains the same two sets of fractures observed at the western part, plus a set of fractures with a moderate dip (between 15° and 45°) with NE trend. This later set of fractures is less frequent and has a variable trace length between 0.5 and 2.5 m; their veins have a width of 2 mm. The fracture density of all the fracture set is between 1 and 4 m' 1 . Although the rock mass at the eastern part of the drift at the level 6A contains three sets of fractures, it is less permeable than the one located at the western part considering its lower fracture density. Consequently, grounwater flow would be more intense in the rock mass at the western part of the drift at the level 6 A of the mine.The results of hydraulic testing in boreholes in the rock mass located immediately under the drift 6A and over a lengh of 48 m, have shown that in the eastern part of this excavation, the hydraulic conductivity of the rock mass is low and constant, between 1 xlO" 10 and 1 xlO " n ms"1 . In the central part of this drift, located just under the old excavations, the rock mass hydraulic conductivity is higher and increases with depth from 1 xlO" 11 and 1 xlO ' 6 ms" 1 , which is in accordance with the higher fracture density in this part of the drift.Hydrogeochemical results show that waters sampled from boreholes at the mine are of neutral pH and contain high concentrations in ions, such as Ca, SO4 and metals. Calcium originates from the dissolution of calcite which is in abundance in fractures. Sulfate and metals originate from sulfide mineral oxidation present in fractures as well as in the rock matrix. Waters at a bulkhead at the base of the old excavations and the mixing waters at the surface, pumped from all ...

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Section: Processus Hydrochimiquesunclassified

Étude des processus chimio-hydro-mécaniques dans un massif rocheux fracturé perturbé par une exploitation minière :

Benlahcen¹

2003

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“…Many reactions either mechanical pressure or chemical dissolution are involved in rock weathering. Dissolution is certainly the main cause of limestone weathering due to its mineralogy [5][6] [7]. Indeed one of the main mineral of limestone is calcite (CaCO 3 ).…”

Section: Introductionmentioning

confidence: 99%

Multi-scale analysis of water alteration on the rockslope stability framework

et al. 2014

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ABSTRACT:Water is an important weathering factor on rock discontinuities and in rock mass mechanical behavior. The increase of rainfall in frequency or in intensity highlights some problems on the rock slope stability analysis. The aim of this paper is the multi scale analysis of the chemical impact of water on rock (surface roughness and matrix). In this study we show how water induces degradation and thus may decreases the stability of the discontinuous rock mass. Water is known to have significant erosion and dissolution effects on rock surface or rock matrix. The chemical features of water such as temperature, pH or salinity make it a "good" candidate to rock degradation. This study has two main components. The first one is the study of water-solid chemical mechanisms and the other is the analysis of the mechanical response of the discontinuity modified by the water alteration. The stability of the rock mass is naturally a function of the type and the space distribution of discontinuities. The study aims also to evaluate the effect of water flow on the rock slope stability and it is performed at two space scales: laboratory (micro scale and macro scale) and in situ scales. The last one is still under investigation and will be presented.

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“…Some of the difficulties of buffering the pH by CaCO 3 might be due to the lack of understanding the 77 system instead of the CaCO 3 buffering capacity itself. Although there have been extensive studies on CaCO 3 dissolution and precipitation in H 2 O-CO 2 -CaCO 3 systems (Arakaki & Mucci, 1995;Buhmann & Dreybrodt, 1987;Dreybrodt et al, 1996;Morse et al, 2007;Plummer & Wigley, 1976;Svensson & Dreybrodt, 1992), fewer investigations have been reported on the kinetics of CaCO 3 dissolution (and its buffer capacity) in biological systems where CO 2 and organic products are produced. A good understanding of the interactions among processes that control the pH can provide a firm basis for practical application of CaCO 3 as a neutralizing agent in biological processes.…”

Section: Introductionmentioning

confidence: 99%

“…The reason for it is that while the mass transfer constant (k l a) for CO 2 and the specific product production rate (q s ) (for a common mixed culture anaerobic process) are on the order of 1 × 10 -2 s -1 and 2 × 10 -4 s -1 , respectively (Merkel & Krauth, 1999;Zeebe & Wolf-Gladrow, 2001); the rate constants of other reactions like speciation, complexation and precipitation/dissolution are by nature occurring at much higher rates and therefore can be considered practically instantaneous. As an example, the rate constant of the relatively slower reaction of HCO 3 -+ H +  CO 2 (aq) is still in the order of 12 s -1 (Dreybrodt et al, 1996;Zeebe & Wolf-Gladrow, 2001). The process of CaCO 3 dissolution can also be seen as an equilibrium reaction when finely powdered calcite is used because it is no longer surface controlled (solution volume to surface area of powdered CaCO 3 , V/A ratio, is lower than 10 -6 m 3 /m 2 ) (Dreybrodt et al, 1996).…”

Section: Introductionmentioning

confidence: 99%

“…As an example, the rate constant of the relatively slower reaction of HCO 3 -+ H +  CO 2 (aq) is still in the order of 12 s -1 (Dreybrodt et al, 1996;Zeebe & Wolf-Gladrow, 2001). The process of CaCO 3 dissolution can also be seen as an equilibrium reaction when finely powdered calcite is used because it is no longer surface controlled (solution volume to surface area of powdered CaCO 3 , V/A ratio, is lower than 10 -6 m 3 /m 2 ) (Dreybrodt et al, 1996). Due to the interactions of all these processes (kinetically controlled reactions and reactions in equilibrium), it is not obvious what are the individual effects of different factors on the pH (Merkel & Krauth, 1999).…”

Section: Introductionmentioning

confidence: 99%

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