Hydrodynamic Factors Influencing Mineral Dissolution Rates

Published

March 9, 2020

Author(s)

Nicos Martys, Jeffrey W. Bullard, Pan Feng, Shaoxiong Ye

Abstract

Solution flow profiles near a mineral surface can have significant influences on the local thermodynamic driving force and, potentially, the rate-controlling kinetic mechanism of its dissolution or precipitation. These influences are investigated here both by \textit{in situ} digital holographic microscopy of calcite in flowing pure water and by lattice Boltzmann reaction-transport simulations using close to the same macroscopic flow rates and sample geometry as the experiments. The measurements show that the median dissolution rate along the crystal surface decreases significantly with distance along the flow direction. At lower flow rates, localized growth is sometimes observed near the trailing edge of a macroscopic crystal even though pure water is injected near the crystal's leading edge. The simulations confirm that the lower rates are caused by an accumulation of dissolved species as the solution flows from the leading to the trailing edge. The experiments and simulations both indicate that the effect is lessened as the flow rate increases but never becomes negligible within the range of flow rates examined. This study implies that dissolution rates are significantly influenced by near-surface conditions even under relatively high flow rates where a surface process, not diffusion, controls the rate.

Citation

Chemical Geology

Pub Type

Journals

Keywords

Lattice Boltzmann simulation, digital holographic microscopy, dissolution kinetics, calcite

Citation

Martys, N. , Bullard, J. , Feng, P. and Ye, S. (2020), Hydrodynamic Factors Influencing Mineral Dissolution Rates, Chemical Geology (Accessed December 26, 2024)