High-efficiency enrichment process of uranium from amidoxime-functionalized fibers after treated by alkaline elution system

Developing an efficient uranium enrichment process for large-scale eluates from marine-tested fibers is crucial for filling the gap in the downstream of seawater uranium extraction. Alkaline elution of 10 kg real marine-tested fibers yielded 33 L of clear eluate after pretreatment, where uranium existed mainly as [UO 2 (CO 3 ) 2 ] 2− , [UO 2 (CO 3 ) 3 ] 4− , and [UO 2 (O 2 )(CO 3 ) 2 ] 4− species with a concentration of 11.98 mg/L, while magnesium concentration was up to 352.48 mg/L.MIP analysis selected D201 resin with more and larger pores, which showed better uranium adsorption due to a maximum electrostatic potential of 114.93 kcal/mol via simulation. 1 kg of D201 resin was used in a self-developed ion exchange equipment (maximum 100 L eluate per run) for concentration and purification. After 5 days of enrichment, 3 L of uranium concentrate was obtained, with uranium concentration increased to 121.48 mg/L and magnesium reduced to 14.9 mg/L. Ammonia water was added to the concentrate for precipitation, collecting 1112.45 mg of uranium product. The uranium precipitation rate was 99.27 %, and that of magnesium was only 31.1 %. The overall enrichment efficiency reached 93.13 % for uranium. ICP results showed the uranium mass fraction in the product was 33.1 %. TI-MS results indicated the U-235 abundance (≈0.72 %) was consistent with natural levels, and U-234 abundance (0.0064 %) was, slightly higher than natural, but still qualified it as natural uranium. This study provides an innovative enrichment process and theoretical support for efficient downstream uranium recovery in seawater uranium extraction.