| 摘要 |
A method is disclosed to separate the heavy rare earth elements Lu through Sm plus Y by an ion-exchange process called selective elution. Mixed rare earths are saturated onto a loading column containing sulfonic resin. Iminodiacetic resin in a separation column is conditioned into the hydrogen and ammonium form before it is saturated with rare earth retaining ion. The rare-earth retaining ion has an atomic weight at least as heavy as the heaviest rare earth element being separated. The hydrogen form section is positioned down stream of the ammonium form resin. Chelating solutions like ammonium EDTA are put through the loading and then the separation column to separate the rare earth elements. The hydrogen form iminodiacetic resin is very selective for separating rare earth elements. By using an ammonium EDTA solution with pH 8.2 to 8.6, the iminodiacetic resin in separation column is returned to the proper ratio of ammonium and hydrogen form resin. The process uses a solution velocity of 1-10 cm/min through the columns. The separation column contains about half as many moles of retaining ion as the loading column contains mixed rare earth. EDTA solution containing impure rare earth from previous runs is recycled and increases rare earth recovery. These aspects singularly and in combination are an improvement over prior art.
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