GB127555A - Improvements in the Extraction & Purification of Thorium Compounds. - Google Patents

Abstract

127,555. Lindsay Light Co., (Assignees of Ryan, L. W.). May 29, 1918, [Convention date]. Thorium oxide, fluoride, sulphate, and carbonate.-The purification or recovery of thorium compounds is effected by first producing the fluoride and then converting this into the anhydrous sulphate by digestion with sulphuric acid at a high temperature. The acid thorium-containing solution resulting from the digestion of, say, monazite sand with acid, is treated, preferably after a preliminary concentration of the thorium, with hydrofluoric acid or a soluble fluoride in the proportions required to precipitate the thorium as fluoride without bringing down any substantial amount of the rare-earth metals present. The filter-cake is heated at 300-400‹ C with concentrated sulphuric acid. The resulting sulphate of thorium may then be separated from admixed sulphates of the rare-earth metals by treatment with a solution of sodium carbonate or bicarbonate to dissolve out the thorium as carbonate, or by interaction with sodium, potassium, or ammonium hydroxide the resulting thorium hydroxide being purified by conversion into a crystallizable salt such as the sulphate.