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Download fileGibbs Energy Minimization Model for Solvent Extraction with Application to Rare-Earths Recovery
journal contribution
posted on 2019-06-03, 00:00 authored by Chukwunwike O. Iloeje, Carlos. F. Jové Colón, Joe Cresko, Diane J. GrazianoThe
emergence of technologies in which rare-earth elements provide
critical functionality has increased the demand for these materials,
with important implications for supply security. Recycling provides
an option for mitigating supply risk and for creating economic value
from the resale of recovered materials. While solvent extraction is
a proven technology for rare-earth recovery and separation, its application
often requires extensive trial-and-error experimentation to estimate
parameter values and determine experimental design configurations.
We describe a modeling strategy based on Gibbs energy minimization
that incorporates parameter estimation for required thermodynamic
properties as well as process design for solvent extraction and illustrate
its applicability to rare earths separation. Visualization analysis
during parameter estimation revealed a linear relationship between
the standard enthalpies of the extractant and respective organo-metal
complexes, analogous to the additivity principle for predicting molar
volumes of organic compounds. Establishing this relationship reduced
the size of the parameter estimation problem and yielded good agreement
between model predictions and reported equilibrium extraction data,
validating the property estimates for the organic phase species. Design
exploration and optimization results map the space of feasible solvent
extraction column configurations and identify the set of optimal design
parameter values that meet recovery and purity targets.