Enrichment of Low Concentration Rare Earths from Leach Solutions of Ion-Adsorption Ores by Bubbling Organic Liquid Membrane Extraction Using N1923

Abstract

A new bubbling organic liquid membrane extraction using primary amine N1923 at large aqueous-to-oil phase ratios was suggested to extract and enrich extremely low concentration rare earths from the acidic sulfate leach solutions of ion-absorbing type rare-earth ores. It was revealed that bubbling organic liquid membrane extraction was in fact an interfacial chemical reaction of organic extractant molecules absorbing at the surface of the organic liquid membrane supported by gas bubbles with the target metal ions in the aqueous solutions. Rare earths with a concentration about 100 mg/L can be extracted selectively and enriched efficiently into the organic extractant liquid membrane layer covered on the surface of dispersed gas bubbles. However, Al in leach solutions was not extractable and remained in the raffinates, due to a kinetic nonequilibrium separation behavior of rare earths and Al on the surface of the organic liquid membrane. It was the differences in reaction rate of rare earths and Al with prim...