# cerium



## skippy (Apr 10, 2011)

I don't know if anyone has been paying attention, but cerium prices have gone up dramatically to over the past little while. If prices stay like this, (big if) then cerium is a potential value in a cat. Wet methods can dissolve the ceria from the catalytic converter substrate which may make it recoverable. Is there a reasonable way to separate cerium (iii, iv) sulfates or chlorides from other chlorides or sulfates that may be in a leach solution (primarily aluminum and magnesium)? Solvent, membrane, selective precipitation?


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## rusty (Apr 10, 2011)

Skippy this is information I found at http://en.wikipedia.org/wiki/Cerium

Production

The mineral mixtures are crushed, ground and treated with hot concentrated sulfuric acid to produce water-soluble sulfates of rare earths. The acidic filtrates are partially neutralized with sodium hydroxide to pH 3–4. Thorium precipitates out of solution as hydroxide and is removed. After that the solution is treated with ammonium oxalate to convert rare earths in to their insoluble oxalates. The oxalates are converted to oxides by annealing. The oxides are dissolved in nitric acid that excludes one of the main components, cerium, whose salts are insoluble in HNO3. Metallic cerium is prepared by metallothermic reduction techniques, such as by reducing cerium fluoride or chloride with calcium, or by electrolysis of molten cerous chloride or other cerous halides. The metallothermic technique is used to produce high-purity cerium.


Precautions

Cerium, like all rare-earth metals, is of low to moderate toxicity. Cerium is a strong reducing agent and ignites spontaneously in air at 65 to 80 °C. Fumes from cerium fires are toxic. Water should not be used to stop cerium fires, as cerium reacts with water to produce hydrogen gas. Workers exposed to cerium have experienced itching, sensitivity to heat, and skin lesions. Animals injected with large doses of cerium have died due to cardiovascular collapse. Cerium(IV) oxide is a powerful oxidizing agent at high temperatures and will react with combustible organic materials. While cerium is not radioactive, the impure commercial grade may contain traces of thorium, which is radioactive. Cerium serves no known biological function.


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## skippy (May 7, 2011)

Thanks for the info there Rusty.

I've read some more on the matter, and the best way I can figure for a simple, although crude separation of cerium from a leach solution wold be a selective precipitation. Cerium (iv) hydroxide is
very insoluble compared to other hydroxides, so I believe it should be the first hydroxide to precipitate with gentle base addition. I'm guessing finding the buyers for the material would be the real trick though.


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## tabor (Jul 1, 2011)

Found this thread via a google search. I have a potential source for about 60 pounds a week of cerium oxide from a glass polishing operation. Would there be any value to it?


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