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How is cerium separated during the processing of bastnasite ore?

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A line graph showing electron probability distributions for gadolinium, with separate curves for 4f, 5s, 5p, 5d, and 6s orbitals. The x-axis shows distance from the nucleus in atomic units and the y-axis shows probability P2(r). — rare-earth element Electron probabilities, P²*(r)*, for the 4f, 5s, 5p, 5d, and 6s electrons of gadolinium.

To separate cerium from bastnasite ore, the material is first processed into a concentrate containing approximately 70 percent rare-earth oxides (REO). This concentrate is then roasted to oxidize the cerium from its trivalent state ( ${Ce}^{3 +}$ ) to the tetravalent state ( ${Ce}^{4 +}$ ).1

Following this oxidation, the material is leached with hydrochloric acid (HCl). This process dissolves the other trivalent rare-earth elements—such as lanthanum, praseodymium, neodymium, samarium, europium, and gadolinium—while the cerium remains as an insoluble residue. This remaining cerium concentrate is then collected and refined into various commercial grades.1