GB1006007A - Purification of uranium yellowcake - Google Patents

Abstract

A substantially pure diuranate is recovered by the removal of impurities from uranium yellow cake by (a) adding an aqueous solution of a salt of carbonic acid, thus forming a soluble uranium carbonate complex; (b) separating insoluble impurities; (c) acidifying to pH of up to 5.2, thus precipitating diuranate; (d) optionally separating the supernatant liquor; (e) acidifying the precipitate to pH 3.0, thus redissolving the precipitate; and (f) treating the solution with a precipitating agent, thus recovering substantially pure diuranate. Uranium yellow cake is a partly purified precipitate containing uranium values and may be impure uranate, diuranate or uranium oxy-hydrate of Mg, Na or NH4. Carbonates used may be potassium, sodium or ammonium carbonates or bicarbonates, singly or mixed, and added till solution is at e.g. pH 7.4 to 8.8, and allowed to react at temperatures, e.g. up to 80 DEG C. The precipitating agent may be NaOH, MgO, or anhydrous or aqueous NH3. Thorium and rare earth values may be recovered from the insoluble impurities from step (b), or these impurities may be recycled to an earlier step.