Improvements in or relating to the production of thorium compounds

Crude thorium hydroxide is dissolved in excess nitric acid, the acid solution boiled to break down any phosphate complexes present and the resulting aqueous solution, with nitric acid present preferably in at least molar concentration, is subjected to organic solvent extraction with tributyl phosphate containing a non-polar organic solvent as diluent. Suitable non-polar solvents are odourless kerosene, dibutyl ether and xylene. The organic solvent extract may be stripped with an aqueous solution of a nitrate or nitrates. According to an example a crude thorium hydroxide sludge containing cerium, neodymium, lanthanum, praseodymium and traces of samarium and uranium was dissolved in 15 molar nitric acid to producea 3-4 molar nitric acid solution containing 250 grammes of thorium per litre. The solution was boiled for half an hour, treated with hydrogen peroxide and reboiled, after which it was diluted to a thorium concentration of 195 grammes per litre and then extracted with 30 per cent by volume tributyl phosphate in xylene in an extractor having four extraction stages and four stripping stages, the stripping solution being a 4-molar solution of aqueous of sodium nitrate. The resulting organic solvent extract contained 42.3 grammes of thorium per litre.