Chemical Engineering and Processing, Vol.127, 127-135, 2018
Efficient enrichment and recovery of rare earth elements with low concentration by membrane dispersion micro-extractors
Membrane dispersion micro-extractors were used both in gas-liquid-liquid system to realize the intensification of REEs extraction at high phase ratio and also in stripping process to recover the rare earth elements (REEs) with low concentration (< 100 mg/L) from industrial waste water. The effects of three phase (organic, aqueous, gas) flow rates on the extraction efficiency were investigated. The results indicated that 2 m of the out-let channel was required to reach 95% or above, and the overall volume mass transfer coefficient K(L)a was enhanced around 3.0-4.5 times compared with liquid-liquid system. The results of stripping process revealed that the stripping efficiency of Nd (III) could reach 98% and the total enrichment factor was 200. Finally, the mixture of REEs was employed as a model of industrial raffinate. The total enrichment factor was 150, which exhibited a potential method for the effective utilization of REEs from waste water.