DEVELOPMENT OF INNOVATIVE PROCESSES FOR THE SEPARATION OF HIGH PURITY URANIUM FROM PHOSPHORIC ACID

Phosphoric acid is processed in large volumes by Indian industries, into fertilizers and detergent phosphates. A major proportion of this acid contains uranium in significant concentration. Phosphates have long been recognized to be an important secondary source of uranium and indigenous development of processes of separation, has been an important area of R&D at BARC [1]. The key step in the separation flowsheet is solvent extraction. In India, the major proportion of phosphoric acid is in the concentrated form, generally called the ‘Merchant Grade’ Acid (MGA). The phosphate content of MGA, expressed as P 2 O 5 weight percentage is ~ 55. Typical analysis is given in Table 1. Viscosity of MGA is high, in the range of 20-50 centipoise. Depending on the nature of phosphoric acid, a particular type of solvent is needed. BARC has recently developed a novel solvent extraction process based on Di-Nonyl Phenyl Phosphoric Acid (DNPPA) which has been patented [2]. Another process has been developed and patented using currently available indigenous industrial solvents for extraction from ~28% P 2 O 5 weak acid (WPA) [3]. The salient details of these two processes are described in this paper, after giving a general description of the overall separation flow sheet. Some recent R&D work is summarized in the concluding part of the paper. More details are available in the published references [4-9].