SEPARATION OF NEODYMIUM AND DIDYMIUM FROM THE RARE EARTHS IN BASTNASITE

摘要

1. A process for the separation of neodymium or didymium from the rare earths contained in bastnaesite comprising : effecting roasting of the bastnaesite, effecting controlled leaching of the roasted bastnaesite by means of a solution of nitric acid using an amount of nitric acid which is substantially equal to the stoichiometric amount of the trivalent rare earths present in the ore, which permits solubilisation of the neodynium and the trivalent rare earths to the exclusion of cerium and the traces of thorium which are found in the form of an insoluble residue which is then separated, and effecting separation and purification of the neodymium or didymium by liquid-liquid extraction as between the aqueous phase formed by the aqueous solution of nitrates of rare earths which is recovered in the preceding step and an organic phase containing a water-insoluble extraction agent, and then recovering the neodymium or didymium from the organic phase.