Lanthanum and neodymium from Egyptian monazite: Synergistic extractive separation using organophosphorus reagents

A systematic liquid–liquid extraction of lanthanum and neodymium from aqueous nitric acid solutions using a mixture of two neutral extractants, namely trioctylphosphine oxide (TOPO) and trialkylphosphine oxide (TRPO) in kerosene has been investigated. The different factors influencing the extraction affinity of those metals have been studied in detail. The extracted species for both metals have been found in the form of [M(NO3)3(TOPO)(TRPO)¯], where M refers to the metal ion. The temperature had a negative effect on the extraction of the metals where the extraction process has been found to be spontaneous in nature and associated with exothermic reaction. Since yttrium is accompanied with these metals in monazite ore, the extraction of Y(III) has also been studied. Based on the results obtained, a proposed method has been suggested to extract and separate the above metals from the hydrous oxide cake resulted by alkaline leaching of Egyptian monazite and a schematic diagram explaining the process has been presented.

A proposed flow sheet displaying the recovery of different metal values from Egyptian monazite ore after alkaline leaching using solvent extraction technique.Figure optionsDownload as PowerPoint slideHighlights
► Organophosphorus reagents were used for extraction of La, Nd and Y from nitrate medium.
► The extraction showed a dependence on nitrate and extractants concentrations.
► Temperature decreased the extraction associated with exothermic processes.
► A suggested method was proposed for separation of REEs from Egyptian monazite.