Recovery of uranium, vanadium, yttrium and rare earths from phosphoric acid by a precipitation method

Abstract

Commercial procedures for recovery of uranium from phosphoric acid are all based on solvent extraction techniques. Recovery of uranium from phosphoric acid in combination with direct production of concentrated acid is not possible on a commercial scale using solvent extraction. When a dispersion agent such as acetone, and a precipitation reagent - NH 4F - are added, uranium can be precipitated from high concentration (52% P 2O 5), as well as low concentration phosphoric acid (∼30% P 2O 5) with 0.6 kg acetone/kg P 2O 5 and 60 g NH 4F/kg P 2O 5. Variation of all parameters, such as uranium valence, phosphoric acid concentration, type and quantity of the dispersion and precipitation agents, has made it possible to develop on a laboratory scale a preferential mode of operation which appears to make uranium recovery from high concentration acid even simpler than recovery from acid of low concentration. This method also enables recovery of ⩾90% of the yttrium and ⩾80% of the rare earths contained in the phosphoric acid. To precipitate vanadium much more acetone must be used. The economic calculations presented here show that uranium recovery by the precipitation method is considerably less expensive than recovery by extraction or by other proposed routes: $60/lb at phosphoric acid capacity of 300 kt/a P 2O 5 with solvent extraction and $41/lb yellow cake with the new precipitation route and the same capacity. At present uranium prices ($28/lb yellow cake), the precipitation method does not make uranium recovery by precipitation an economic proposition in the case of plants of moderate phosphoric acid capacities (about 300 kt/a P 2O 5); however, in combination with recovery of yttrium and/or rare earths it appears to become economic - $28/lb yellow cake - at this moderate capacity.