Separation of plutonium

摘要

843,481. Separation of plutonium. UNITED KINGDOM ATOMIC ENERGY AUTHORITY. Feb. 6, 1946 [Feb. 3, 1945], No. 3809/46. Drawings to Specification. Class 39(4). Plutonium is recovered from solution by forming a precipitate of a fluoride in the solution together with a precipitate of lead sulphate, whereby plutonium is carried down with the fluoride precipitate. The lead sulphate gives a more rapid settling of the precipitate and an improved separation of plutonium. Lanthanum fluoride is the preferred fluoride, but potassium plutonium fluoride is also referred to. The solution treated may be that obtained following bismuth phosphate precipitation of a solution of neutron-irradiated uranium according to U.S.A. Specification 2,785,951. The fluoride and lead sulphate precipitates are preferably formed at the same time by mixing solutions containing hydrogen fluoride, lanthanum nitrate, lead nitrate, and sulphuric acid. The lanthanum nitrate solution may be added to the hydrogen fluoride solution or vice versa. The precipitate is digested before separation and may then be washed and treated with alkali to form a lanthanum hydroxide precipitate which carries the plutonium, leaving the lead in solution ; the precipitate may be dissolved in nitric acid and plutonium precipitated as fluoride or peroxide. The Specification as open to inspection under Section 91 refers also to the presence of lead sulphate during the precipitation of impurities with a fluoride, leaving the plutonium in solution in the oxidised state; the addition of stannic, aluminium, antimony, and arsenic compounds in place of lead sulphate is also mentioned. An additional example describes the improved precipitation of lanthanum fluoride in the presence of lead ions without precipitation of the sulphate. This subject-matter does not appear in the Specification as accepted.