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Open AccessArticle

Predicting the Logarithmic Distribution Factors for Coprecipitation into an Organic Salt: Selection of Rare Earths into a Mixed Oxalate

by 1,2,* and 1
1
Department of Chemical Engineering, University of Western Australia, Crawley, WA 6009, Australia
2
Watts & Fisher Pty Ltd., Crawley, WA 6009, Australia
*
Author to whom correspondence should be addressed.
Minerals 2020, 10(8), 712; https://doi.org/10.3390/min10080712
Received: 30 June 2020 / Revised: 5 August 2020 / Accepted: 6 August 2020 / Published: 12 August 2020
(This article belongs to the Special Issue Leaching of Rare Earth Elements from Various Sources)
Thermodynamic modelling of a leaching system that involves concurrent precipitation depends on an understanding of how the metals distribute into the precipitate before an assessment of solubility can be made. It has been suggested in the past that a pair of rare earths (A and B) in solution will separate from each other by oxalate precipitation according to a logarithmic distribution coefficient (λ), determined by the kinetics of the precipitation. By contrast, the present study hypothesises that λ may be approximated from thermodynamic terms, including the solubility product (KSp) of each rare earth oxalate and the stability constant (β1) for the mono-oxalato complex of each rare earth. The proposed model was used to calculate λ between pairs of rare earths. An experimental study was conducted to determine λ between selected pairs using homogenous precipitation through the hydrolysis of an oxalic acid ester, with fairly close agreement to the values under the proposed model. Though this model requires more thorough testing, as well as application to other organic salts, it may provide insight into distribution factors of a precipitate formed by a sequence of organic complexes. View Full-Text
Keywords: rare earths; distribution factor; selective precipitation; oxalates; organic complexes rare earths; distribution factor; selective precipitation; oxalates; organic complexes
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MDPI and ACS Style

Watts, H.; Leong, Y.-K. Predicting the Logarithmic Distribution Factors for Coprecipitation into an Organic Salt: Selection of Rare Earths into a Mixed Oxalate. Minerals 2020, 10, 712. https://doi.org/10.3390/min10080712

AMA Style

Watts H, Leong Y-K. Predicting the Logarithmic Distribution Factors for Coprecipitation into an Organic Salt: Selection of Rare Earths into a Mixed Oxalate. Minerals. 2020; 10(8):712. https://doi.org/10.3390/min10080712

Chicago/Turabian Style

Watts, Harry; Leong, Yee-Kwong. 2020. "Predicting the Logarithmic Distribution Factors for Coprecipitation into an Organic Salt: Selection of Rare Earths into a Mixed Oxalate" Minerals 10, no. 8: 712. https://doi.org/10.3390/min10080712

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