Evaluation of Heavy Rare Earth Extraction Strategies from Fluorapatite Mineral Using D2EHPA as an Extractant

Abstract

Various heavy rare-earth separation strategies for separating light rare-earth elements and calcium have been evaluated in this study. Estonian phosphorite ore (fluorapatite) was dissolved in either 2 M nitric or hydrochloric acid, and the leachate was partially saponified thereafter with 2 M NaOH. The acid leachate was extracted with diluted NaOH-saponified D2EHPA using kerosene or toluene as solvents. The calculated extraction efficiencies and selectivities were compared with those reported in previous extraction studies using undiluted pure D2EHPA in strongly acidic media. It was found that extraction efficiencies are higher with diluted and saponified D2EHPA. However, separating heavy rare earth elements from light rare earth elements and calcium does not appear viable under mildly acidic conditions with diluted, saponified D2EHPA. Thus, for the most selective heavy rare-earth separations, extraction from strongly acidic media with pure D2EHPA appears to be a superior option.