Rate constants for Uranyl mineral, swartzite

[KDanny]

Hello,

 

I’m trying to model precipitation of the uranium-bearing mineral, Swartzite (CaMg(UO₂)(CO₃)₃•12(H₂O)), from solution. When I equilibrate my ground water chemistry of interest using REACT and X1T, Swartzite is the only uranium-bearing mineral to be supersaturated (SI>0 [sI=0.45]).

 

I’m using an updated thermodynamic database, that includes uranium data determined after the discovery of Ca₂UO₂(CO₃)₃⁰ CaUO₂(CO₃)₃^-2and MgUO₂(CO₃)₃^-2 complexes by Bernhard in 1996. I can’t find appropriate kinetic rate constants for the precipitation and dissolution of Swartzite to include in my REACT and X1T models. I plan to include rate constants of an alternate uranium-bearing mineral in place of Swartzite, such as Schoepite or Rutherfordine if no data are available. However, such substitution will render my output a gross approximation.

 

Has anyone determined or located reliable kinetic rate constants for Swartzite while modeling uranium mineral saturation? Has anyone been unable to find kinetic rate constants for a mineral, and ended up substituting in a similar mineral?

 

Any help would be useful. Thanks.

GWB_U_02172012.dat