2944.     ---------------.  [RUHRCHEMIE, A.-G.]  [Thorium Regeneration.]   FIAT Reel K-20, 1938, frames 24-31; PB 70,211; TOM Reel 287.

        Auergesellschaft A.-G. has developed the following method:  Fe-Th sludge is dissolved in HCl at a temperature of 80°.  After cooling, the bulk of the solution is siphoned off, the residue is filtered, and the whole is mixed with H₂SO₄.  The sulfate precipitates are centrifuged and covered with dilute H₂SO₄.  The Th sulfate is then stirred with water and converted to Th hydrocarbonate.  The yield of ThO₂ by this method is 94%.  The method is compared with the Ruhrchemie method.  The maximum content of SO₃ in the Th hydrocarbonate is given as 0.3%.