Multicomponent reactive transport modelling: Applications to ore body genesis and environmental hazards

The interplay of chemical and mechanical effects is of crucial importance for understanding and solving key problems of geology, engineering and environmental science. We begin with an outline of the governing equations for a coupled multicomponent reactive transport model. Thermal coupling and heat flow is also considered. The reaction part of the model is kept very general and applies to a wide variety of problems including simulation of in situ leaching, mineralization (ore body genesis), environmental hazards and calcite leaching to name just a few. We briefly introduce the CSIRO symbolic finite element solver FASTFLO (http://www.cmis.csiro.au/fastflo) and illustrate the theory by a number of finite element solutions. While focussing initially on reactive transport dominated problems (deformation and damage negligible) we close with a limit load problem involving chemically induced reduction of the yield strength. We consider a stiff, smooth strip foundation on an infinite half plane (Prandtl case). The substrate deforms and partially plastifies (von Mises yield, Prandtl-Reuss flow rule). We then prescribe a constant concentration of a leachant on the surface of the half plane. The concentration of the leachant diffuses through the half plane, lowering the yield strength and ultimately causing unacceptably large deformation of the structure.