Conceptual model of mineral dissolution

[peterwadeuk]

Greetings good people.

I am exploring the kinetic dissolution of forsterite and reprecipitation of minerals at the reactive surface.

I need to model what happens close to the surface of the mineral as it dissolves, meaning that I am modelling where the diffusion gradient into solution matters.

I thought to model high concentrations of dissolution products by simulating a forsterite bulk with low, e.g. 1% porosity, to simulate the interface. I have done so and generated results that are not on first glance implausible.

But I am concerned about my conceptual model.

Is this a reasonable way to simulate reactions close to the solid/solution boundary of a mineral? Can anyone see any immediate pitfalls?

All the best,
Peter

[dlparkhurst]

The simplest way would be to have a batch reaction where the forsterite dissolves, either kinetically (KINETICS) or in specified increments (REACTION). The products could be formed by equilibrium (EQUILIBRIUM_PHASES) or kinetically (KINETICS). The conceptual model would be that the reactions are happening on the surface of the mineral.

Alternatively, you could set up a diffusion only TRANSPORT calculation. A boundary condition might be a fixed solution at one end of a pore. You would have to decide on the reactions (probably KINETIC for the forsterite), equilibrium or kinetic for the products. You can also place where you want the forsterite in the pore (1D column) and where you allow the products to form.  You could allow the reactions throughout the column or separate them in space.