Chemical elements
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Caesium Production





Production

The following processes are the methods for the recovery of cesium from pollucite: acid methods, sintering and direct recovery. In acid methods halogen-hydrogen acids, mostly HCl or H2SO4, are used. Pollucite is decomposed by H2SO4, Cs3[Sb2Cl9] is precipitated from the solution treating it with SbCl3; after that caesium salt is poured over by hot water or treated by ammonia solution yielding CsCl. Caesium alums CsAl(SO4)2x12H2O are the product of pollucite decomposed by sulphur acid.

Arend's method is the most accepted sintering process: pollucite is roasted with CaO and CaCl2 mixture, the sinter is leached in autoclave with hot water, the solution is evaporated with H2SO4 for separating CaSO4. The residue is treated by hot water, after which Cs3[Sb2Cl9] is precipitated.

The direct method: granulated pollucite mixture with calcium or aluminium is heated until 900°C in vacuum.

Alums and nitrates fractioning crystallization methods as well as their precipitation and Cs3[Sb2Cl9], Cs2[SnCl6] recrystallization are used for separating caesium, rubidium and potassium and obtaining pure caesium compounds. Ion chromatography on synthetic resin and inorganic ionites (for instance, clinoptilolite, etc) also may be used as well as extraction by phenol derivatives, such as 4-sec-butyl-2-methylbenzyl phenol, C7-C9 alkyl phenols etc. Polyhalides are used for high-purity caesium recovering.

Caesium metal may be processed in basic metallothermy via CsC reducing by calcium or magnesium at 700-800°C under 0.1-10 Pa with following rectification and vacuum distillation.\n


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