- 作者: M. C. CHEN
- 作者服務機構: Union Industrial Research Institute Ministry of Economic Affairs
- 中文摘要: Monazite was decomposed with sodium hydroxide solution in an autoclave.After the extraction of the thorium, the rare earth hydroxides suspension containsabout 9% (Wt./Vol.) Ce(OH)3 in 4 l. within the temperature range of 80o-100oC. Inthe presence of about 1.7%(Wt./Vol.) sodium hydroxide, the suspension wasoxidized with oxygen which was about twelve times as much as the theoreticalquantity for the oxidation of Ce(OH)3。.The ratio of the oxidation reached as highas 95% when the suspension was oxidized with the rate of 700 ml./min. of oxygen.When it was oxidized with air and we wish to get the same result, the rate of theair was not required to increase in proportion to the oxygen in the air. The oxidized rare earth nitrate solution was treated with ammonium hydroxidefor adjusting the pH value of the solution at 3. All the Ce(OH)4 could be precipi-tated and separated from the other rare earth elememts. The purity of CeO2 reachedover 99%, as the precipitate was treated with the crystallization method of ammo-nium cerium nitrate. As the rare earth hydroxides being oxidized and separated iron, aluminum andtitanium with oxalic acid, the percentage of CeO2 increased, The particle size ofoxides burnt from carbonate was a一〝ong the smallest. The pH value of these oxidescould be adjusted to an adequate pH value by being washed and dried, and theoxides are used as a polishing material.
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