A three-dimensional microstructural model of reactions and transport in aqueous mineral systems

Abstract

A stochastic three-dimensional microstructure model is introduced for simulating spatial and temporal variations in aqueous mineral systems. Dissolution, nucleation, precipitation and solute transport are governed by local probabilistic rules applied on a regular computational lattice. The model is shown to accurately simulate ion diffusion in a dilute electrolyte. The reaction algorithms faithfully reproduce kinetics expected from standard rate equations, and reversible reactions are shown to converge to the correct equilibrium state determined by detailed balance of forward and reverse reaction rates, or the law of mass action. Accounting for the exponential temperature dependence of the reaction rate constants is shown to provide accurate predictions of the influences of temperature on both the kinetics and equilibrium of reactions. A simulation of the hydration of a generic metal oxide in water demonstrates the important relationships between microstructure development and the mechanisms of nucleation, growth and solute diffusion.