Simultaneous recovery of rare earths and uranium from wet process phosphoric acid using solvent extraction with D2EHPA

摘要

AbstractIn most cases, wet-process phosphoric acid (WPA) contains trace amount of rare earth elements and uranium, which ultimately enter and accumulate in soil and may cause environmental damages. In order to remove and recover these elements, studies about solvent extraction of heavy rare earth elements (HREEs) and uranium (U) with D2EHPA, selective stripping of HREEs from U, and evaporation precipitation of light rare earth elements (LREEs) were investigated. Extraction efficiency of U from WPA was greatly enhanced, but HREEs extraction were significantly retarded when using the solvent mixture of di- (2-ethylhexyl) phosphoric acid (D2EHPA) and tri-butyl-phosphate (TBP) or tri-octyl-phosphine oxide (TOPO) compared with D2EHPA alone. 89.4% and 94.2% accumulative two-stage extraction efficiencies of HREEs and U, respectively, were achieved with 1.0M D2EHPA alone. And more than 98.1% HREEs were selectively stripped from loaded D2EHPA with 6.0M HCl via three stages. In addition, LREEs were enriched to 1204.3μg/g in evaporation sludge during the concentration process of phosphoric acid from 30% to 50% P2O5, and the filtration performance was greatly improved. Based on the studies, an alternative process was developed to recover and group LREEs, HREEs and U during the phosphoric acid production.Graphical abstractDisplay OmittedHighlights?Simultaneous extraction of heavy rare earth elements (HREEs) and uranium from phosphoric acid (WPA)?Selective stripping of HREEs from loaded organic phase?Enrichment of light rare earth elements (LREEs) in evaporation sludge during the concentration process of WPA?Significant improvement of filtration speed of concentrated phosphoric acid?Alternative process for recovery and grouping HREEs, LREEs and U during the production of phosphoric acid]]>