EGU2020-12253
https://doi.org/10.5194/egusphere-egu2020-12253
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Dissolution of a single mineral grain: comparison of microfluidic experiments with pore-scale simulations

Piotr Szymczak1, Filip Dutka1, Vitaliy Starchenko2, Florian Osselin3, Silvana Magni1,4, and Anthony J.C. Ladd5
Piotr Szymczak et al.
  • 1Faculty of Physics, University of Warsaw, Poland (piotr.szymczak@fuw.edu.pl)
  • 2Chemical Sciences Division, Oak Ridge National Laboratory, USA
  • 3Institut des Sciences de la Terre d’Orléans, France
  • 4Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland
  • 5Department of Chemical Engineering, University of Florida, Gainesville, USA

We investigate the dissolution of a single grain of soluble mineral by microfluidic experiments and numerical simulations. The experiments use gypsum cylinders (10 mm radius, 0.5 mm thick) cast from rehydrated CaSO4 hemihydrate. The numerical simulations used a finite-volume discretization of the reactive-transport equations with a mesh that conforms to the evolving shape of the mineral. Using the coefficients for dilute aqueous ions, we overpredict the dissolution rate by about 25%. However, including the Debye-Huckel correction for the ion activity gives a substantial reduction in diffusion across the boundary layer at the dissolving solid surface and brings the simulation time scale into quantitative agreement with experiment.

The asymmetry introduced by the flow causes the initially cylindrical sample to take on a shape resembling one half of a figure eight, with the tip pointing in the downstream direction. The simulations give a near perfect match to the experimental size and shape. We quantify the evolution of the volume of the grain and its surface area, as well as its overall shape as the function of the Peclet number. Next we discuss the differences between the geometric surface area and the reactive surface area of a dissolving grain and explore a potential use of these results to upscale the reactive transport problem and obtain the effective reaction rates in a multi-grain system.

How to cite: Szymczak, P., Dutka, F., Starchenko, V., Osselin, F., Magni, S., and Ladd, A. J. C.: Dissolution of a single mineral grain: comparison of microfluidic experiments with pore-scale simulations, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-12253, https://doi.org/10.5194/egusphere-egu2020-12253, 2020

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