A new set of Pitzer interaction parameters to describe solution properties and solid-liquid equilibria in the Li-Ca-Cl-H 2 O system at 298.15 K

Arnault Lassin (1) , Anne-Laure Thadée (1) , Adeline Lach (1) , Laurent André (1) , Sylvain Guignot (1) , Jean-Paul Serin (2) , Pierre Cézac (2)

1 BRGM - Bureau de Recherches Géologiques et Minières (BRGM)
2 LATEP - Laboratoire de Génie Thermique Énergétique et Procédés (EA1932)

The Li-Ca-Cl-H 2 O system has been described in previous works using different modelling approaches [1-3], including the Pitzer equations [4]. These models are self-consistent but cannot be combined with recent developments aiming at describing larger chemical systems such as H-Li-Na-K-Cl-OH-H 2 O [5,6]. The objective of the present work is thus to develop a new set of Pitzer interaction parameters for the Li-Ca-Cl-H 2 O system consistent with these latter models, at 298.15 K. This task was done in two steps. First, the description of the Ca-Cl-H 2 O subsystem has been extended to the metastable super-saturation region by refining the recent model of Lach [7] using the osmotic coefficient data selected by [8]. Then, using osmotic coefficient or water activity data for LiCl-CaCl 2 mixtures [9,10] and solubility measurement data [10-12], the new set of specific interaction parameters and solubility products has been determined. Both types of data can be reproduced satisfactorily (see figure below) using the geochemical code PhreeSCALE [13], and it is now possible to envision the extended description of the H-Li-Na-K-Ca-Cl-OH-H 2 O chemical system at 298.15 K. Figure: The Li-Ca-Cl-H 2 O system at 298.15 K. (A) Solubility diagram and (B) iso-activity of water in mixtures. Symbols are experimental data, full lines are model results.

Mots clés: Li-Ca-Cl ternary system; Pitzer model

Domaines: Géochimie

Arnault Lassin, Anne-Laure Thadée, Adeline Lach, Laurent André, Sylvain Guignot, et al.. A new set of Pitzer interaction parameters to describe solution properties and solid-liquid equilibria in the Li-Ca-Cl-H 2 O system at 298.15 K. 25ème Réunion des sciences de la Terre (RST 2016), Oct 2016, Caen, France. , 2016. ⟨hal-01332185⟩