The Utilization of Primary Amines for separation of HREEs from LREEs in Sulphate Media

In recent years, several studies have been conducted to improve the process steps of rare earth elements (REEs) production. Beneficiation & separation stages varies according to type and concentration of impurities. One of the most complex process can be the selective separation of rare earth elements from each other due to their similar physical and chemical properties. At industrial scale,msolvent extraction is the most common separation and enrichment technology for REEs.
The efficiency of solvent extraction depends on several factors. The selection of extractant strongly depends on the composition of the leachate. In sulphate media, carboxylic acids are preferred because of their high extraction rates. Furthermore, primary amines can be used for extraction of rare earths in sulphate media. In amine system, extraction follows a reverse order comparing to cationic extractants.
In the presented study, primary amine Primene 81-R was selected as an alternative extractant in order to investigate its potential for a highly selective separation of REEs. The separation of HREEs from LREEs was determined in dependence on pH and concentration of the extractant using a model solution consisting mainly of LREES (97% of the total REE content). In the extraction experiment, approximately 40-50% of LREE were extracted into the organic phase, while the extraction of HREEs was obtained to be only between 5-30% under these conditions. However, for further development of the solvent extraction process, optimization studies are ongoing.