Large Phase Ratio Extraction and Enrichment of Rare-Earth Ions By a Novel Gas-Assistant Column Extractor

We proposed a novel gas-assistant column extractor to perform extraction and enrichment of rare-earth ions from low content aqueous leach solutions with large aqueous-to-oil phase ratios. Batch and continuous experiments were conducted to test enrichment and separation efficiency of rare-earth ions. Experimental investigations on the feed-in solutions containing La, Pr, Nd and Lu about 10 to 100 mg/L were carried out in order to determine the extraction performance of the gas-assistant column extractor. The results demonstrate that enrichment and separation efficiency of light and heavy rare-earth ions is dependent on air bubbling rate, solvent flow rate and aqueous-to-oil phase ratio. The operational aqueous-to-oil phase ratio can be reached even more than 300:1, and percent extraction of rare-earth ions were above 95% after 5min. of air bubbling. The present work highlights a novel strategy to achieve extraction processes requiring higher aqueous-to-oil phase ratios, so that difficulties in enrichment and recovery of rare-earth ions with low concentrations (<100 mg/L) by traditional mixer-settler can be solved.