"The U.S. Bureau of Mines investigated the separation of heavy rate-earth elements (REE) in an ion exchange process. An ion-exchange column consisting of two sections, a loading section and a separation section, provides high 1evels of REE loading and good REE separation with an expected processing cycle of less than a month, while current ion-exchange technology requires more than 5 mouths. A different resin is used in each section: sulfonic resin in the loading section and iminodiacetic resin in the separation section. The separation section is further divided into two segments: the first conditioned with NH4 and the second with acid. Erbium is loaded onto both segments of the separation column as a retaining ion. Bands of mixed REE eluting between separated bands of pure REE were recycled directly to the columns. Without mixed-band recycle, over 80% of the REE eluted from the column was separated into fractions with 99% purity of each element; with such recycle, the percentage of separated elements can be increased to around 90%." - NIOSHTIC-2 NIOSHTIC no. 20026516

National Institute for Occupational Safety and Health