Andra thermodynamic database for performance assessment: ThermoChimie

How well suited are current thermodynamic models to predict or interpret the composition of (Ba,Sr)SO4 solid-solutions in geothermal scalings?

“…Calculations are performed assuming (1) 230 bar and 100 °C (reservoir conditions), (2) 1 bar and 70 °C (geothermal plant conditions), and (3) 1 bar and 25 °C (standard conditions). Where applicable, we compare results obtained with the ThermoChimie (SIT.dat Giffaut et al 2014) and Pitzer [Pitzer.dat (Appelo et al 2014)] databases. Solid-solution thermodynamic calculations are performed on the basis of aqueous activities and endmember solubilities from PhreeqC, using MS-Excel or a homemade Python code.…”

“…Instead, Pb is fully gathered in the sulphide mineral galena. Obviously, due to the extremely low solubility of PbS [log 10 (K SP (Galena)) = −31.94, for the formation from Pb 2+ and S 2− at 25 °C (Giffaut et al 2014)], traces of S 2− are sufficient to bind Pb 2+ quantitatively to the sulphide phase.…”

“…Corresponding models are tabulated in thermodynamic databases [SIT. dat (Giffaut et al 2014), Phreeqc.dat, Pitzer.dat (Appelo et al 2014)] and are available for calculations with the geochemical modelling code PhreeqC (Parkhurst and Appelo 2013). As will be shown below, despite the available data pool, there is still considerable uncertainty even with respect to the solubility of the endmember phases.…”

Stability of Clay Barriers Under Chemical Perturbations

“…With increasing code capability, and among other things, more minerals have been taken into account, mineral dissolutioneprecipitation has been considered both at local equilibrium and then kinetically controlled, and special discretization has been refined. At the same time, thermodynamic databases for clay mineral and concrete phases have been improved (Blanc et al, 2012;Giffaut et al, 2014). Therefore in order to evaluate the impact of different modeling assumptions, Marty et al (2014) have performed calculations with a consistent set of data and input parameters arranged with increasing orders of complexity.…”

Synthesis of Calcium Monouranate Particles via an Aqueous Route

“…Geochemical modelling: Aqueous U(VI) speciation across relevant pH values was calculated using the geochemical modelling software PHREEQC and the ANDRA ThermoChimie database 17 with updated thermodynamic data for uranium 18 . The specific ion-interaction theory (SIT) was used for ionic strength corrections.…”