MATERIAL BALANCING AND ESTIMATION OF EQUILIBRIUM CONSTANTS:
APPLICATION TO SOLVENT EXTRACTION TESTS OF RARE EARTH ELEMENTS
*K. Turgeon1-2, C. Bazin1, J.-F. Boulanger1, L. Whitty-Léveillé1-2, D. Larivière2
1
Département de génie des mines, de la métallurgie et des matériaux
1065 Avenue de la Médecine
Université Laval,
Québec, Canada G1V 0A6
2
Département de chimie
Université Laval,
Québec, Canada G1V 0A6
(*Corresponding author: keven.turgeon.1@ulaval.ca)
ABSTRACT
The processing of ore containing rare earth elements leads to the production of a solution of these elements
with impurities such as iron, aluminum and calcium. The separation of the rare earth from the impurities
and the production of individual elements are usually carried out by solvent extraction. The effectiveness
of the extraction conditions and of the reagents is generally tested in the laboratory. This paper deals with
the processing of results from solvent extraction laboratory tests planned to exhibit data redundancy. A
method is proposed to take advantage of the data redundancy to balance the measurements by accounting
for the pH changes during the extraction. The parallel processing of several tests also allows estimating the
equilibrium constants for the extraction. The proposed method produces equilibrium constants that are
more reproducible than values estimated using conventional approaches. The method is illustrated with
solvent extraction tests conducted on synthetic solutions of rare earth elements.
KEYWORDS
Material balance, Solvent extraction, Rare earth elements, Separation, Equilibrium constant