Hydrodynamic factors influencing mineral dissolution rates

We report experimental measurements of the dissolution rate of several carbonate minerals in CO2-saturated water or brine at temperatures between 323 K and 373 K and at pressures up to 15 MPa. The dissolution kinetics of pure calcite were studied in CO2-saturated NaCl brines with molalities of up to 5 mol kg−1. The results of these experiments were found to depend only weakly on the brine molality and to conform reasonably well with a kinetic model involving two parallel first-order reactions: one involving reactions with protons and the other involving reaction with carbonic acid. The dissolution rates of dolomite and magnesite were studied in both aqueous HCl solution and in CO2-saturated water. For these minerals, the dissolution rates could be explained by a simpler kinetic model involving only direct reaction between protons and the mineral surface. Finally, the rates of dissolution of two carbonate-reservoir analogue minerals (Ketton limestone and North-Sea chalk) in CO2-saturated water were found to follow the same kinetics as found for pure calcite. Vertical scanning interferometry was used to study the surface morphology of unreacted and reacted samples. The results of the present study may find application in reactive-flow simulations of CO2-injection into carbonate-mineral saline aquifers.

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Scale dependence of mineral dissolution rates within single pores and fractures

Geochimica et Cosmochimica Acta ◽

10.1016/j.gca.2007.10.027 ◽

2008 ◽

Vol 72 (2) ◽

pp. 360-377 ◽

Cited By ~ 120

Author(s):

Li Li ◽

Carl I. Steefel ◽

Li Yang

Keyword(s):

Scale Dependence ◽

Mineral Dissolution ◽

Dissolution Rates

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A Statistical Approach for Analysis of Dissolution Rates Including Surface Morphology

Minerals ◽

10.3390/min9080458 ◽

2019 ◽

Vol 9 (8) ◽

pp. 458 ◽

Cited By ~ 5

Author(s):

Elisabete Trindade Pedrosa ◽

Inna Kurganskaya ◽

Cornelius Fischer ◽

Andreas Luttge

Keyword(s):

Mineral Dissolution ◽

Etch Pits ◽

Dissolution Rates ◽

Calcite Dissolution ◽

Crystal Dissolution ◽

Vertical Scanning Interferometry ◽

Surface Morphologies ◽

Micrometer Scale ◽

Flow Experiments

Understanding mineral dissolution is relevant for natural and industrial processes that involve the interaction of crystalline solids and fluids. The dissolution of slow dissolving minerals is typically surface controlled as opposed to diffusion/transport controlled. At these conditions, the dissolution rate is no longer constant in time or space, an outcome observed in rate maps and correspondent rate spectra. The contribution and statistical prevalence of different dissolution mechanisms is not known. Aiming to contribute to close this gap, we present a statistical analysis of the variability of calcite dissolution rates at the nano- to micrometer scale. A calcite-cemented sandstone was used to perform flow experiments. Dissolution of the calcite-filled rock pores was measured using vertical scanning interferometry. The resultant types of surface morphologies influenced the outcome of dissolution. We provide a statistical description of these morphologies and show their temporal evolution as an alternative to the lack of rate spatial variability in rate constants. Crystal size impacts dissolution rates most probably due to the contribution of the crystal edges. We propose a new methodology to analyze the highest rates (tales of rate spectra) that represent the formation of deeper etch pits. These results have application to the parametrization and upscaling of geochemical kinetic models, the characterization of industrial solid materials and the fundamental understanding of crystal dissolution.

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Experimental Determination of Chlorite Dissolution Rates

MRS Proceedings ◽

10.1557/proc-353-149 ◽

1994 ◽

Vol 353 ◽

Cited By ~ 4

Author(s):

Christopher A. Rochelle ◽

Keith Bateman ◽

Robert MacGregor ◽

Jonathan M. Pearce ◽

David Savage ◽

...

Keyword(s):

Dissolution Kinetics ◽

Research Programme ◽

Mineral Dissolution ◽

Dissolution Rates ◽

Disturbed Zone ◽

Ph Conditions ◽

Engineered Barriers ◽

The Uk ◽

Mineral Dissolution Kinetics

AbstractCurrent concepts of the geological disposal of low- and intermediate-level radioactive wastes in the UK envisage the construction of a mined facility (incorporating cementitious engineered barriers) in chlorite-bearing rocks. To model accurately the fluid-rock reactions within the ‘disturbed zone’ surrounding a repository requires functions that describe mineral dissolution kinetics under pH conditions that vary from near neutral to highly alkaline.Therefore, an experimental study to determine the dissolution rates of Fe-rich chlorite has been undertaken as part of the Nirex Safety Assessment Research Programme. Four experiments have been carried out at 25 °C and four at 70 °C, both sets using a range of NaCl/NaOH solutions of differing pH (of nominal pH 9.0,10.3, 11.6 and 13.0 [at 25 °C]).Dissolution rates have been calculated and were found to increase with increasing pH and temperature. However, increased pH resulted in non-stoichiometric dissolution possibly due to preferential dissolution of part of the chlorite structure relative to another, or reprecipitation of some elements as thin hydroxide or oxyhydroxide surface coatings on the chlorite.These results also show that chlorite dissolution is appreciably slower than that of albite and quartz at both 25 and 70 °C, but slightly faster than that of muscovite at 70 °C.

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