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# MINERAL_KINETICS¶

Specifies coefficients for kinetic mineral precipitation-dissolution reactions. The rate law is defined through transition state theory, as detailed in section Mineral Precipitation and Dissolution of the theory guide.

where

\(a_m\) = mineral surface area

\({\mathcal P}\) = prefactor (a sum of prefactor rates; if activation energy is provided the Arrhenius equation is applyied to calculate rates at different temperatures)

\(K_m\) = equilibrium constant

\(Q_m\) = ion activity product

\(\sigma_m\) = Temkin constant (default is 1)

\(\beta_m\) = affinity power (default is 1)

\(k_{ml}\) = rate constant

Note that prefactor calculations have not yet been verified.

## Required Cards:¶

- MINERAL_KINETICS
- Opens the block.

## Optional Cards:¶

- <string>
- Gives the mineral name.
- RATE_CONSTANT <float>
- Kinetic rate constant [mol/m
^{2}-sec]. - ACTIVATION_ENERGY <float>
- If specified, used in the prefactor calculations for temperature specific rates (Arrhenius)
- AFFINITY_THRESHOLD <float>
- If specified, rate is only calculated if Q/K >= threshold and sign < 0.
- RATE_LIMITER <float>
- If specified, \(R=-\frac{\Omega}{1+\frac{1-\Omega}{R_{lim}}}\), where \(R_{lim}\) is the rate limiter, \(\Omega=Q/K\), and \(R\) denotes the reaction rate.
- IRREVERSIBLE
- Flag indicating the reaction is irreversible
- SURFACE_AREA_POROSITY_POWER <float>
- Exponent in equation for transient mineral surface area calculated as a
function of porosity, \(\phi\).
A = \(\phi\)
^{SURFACE_AREA_POROSITY_POWER} - SURFACE_AREA_VOL_FRAC_POWER <float>
- Exponent in equation for transient mineral surface area calculated as a function of change in mineral volume fraction.
A = (VF/VF
_{0})^{SURFACE_AREA_VOL_FRAC_POWER} - PREFACTOR
- Parameters for reaction rate prefactors

## Examples¶

CHEMISTRY ... MINERAL_KINETICS Calcite RATE_CONSTANT 1.d-13 mol/cm^2-sec / / ... END