IV.

Extraction of Uranium

In the classical procedure for extracting uranium, pitchblende is broken up and mixed with sulfuric and nitric acids. Uranium dissolves to form uranyl sulfate, UO₂SO₄; radium and other metals in the pitchblende ore are precipitated as sulfates. With the addition of sodium hydroxide, uranium is precipitated as sodium diuranate, Na₂U₂O₇ · 6H₂O, known also as the yellow oxide of uranium. To obtain uranium from carnotite, the ore is finely ground and treated with a hot solution of caustic soda and potash to dissolve out uranium, radium, and vanadium. After the worthless sandy matrix is washed away, the solution is treated with sulfuric acid and barium chloride. A caustic alkali solution added to the remaining clear liquid precipitates the uranium and radium in concentrated form. These classical methods of extracting uranium from its ores have been replaced in current practice by such procedures as solvent extraction, ion exchange, and volatility methods. For the method of producing the artificial isotope uranium-233, see Thorium.