An experimental study on high-purity uranium refining by passing in succession through pulsed extraction, washing, and stripping columns

Abstract

Nuclear-purity uranium was refined by passing a solution of uranyl nitrate in 3–5 M HNO₃ in succession through pulsed extraction, washing, and stripping columns for feeding into the U(III)–U(IV) chemical exchange system for uranium isotope separation. The extractant (tri-n-butyl phosphate, TBP), the diluent (kerosene), nitric acid, ammonium carbonate, sodium nitrate, and water were preliminarily refined to chemical purity. The diameter and height of pulsed columns for uranium purification was 25 and 1500 mm, respectively, and the pulse frequency was 1 s^–1. The content of transition metals (Fe, Co, Ni, Cu, Ag) and Pb, which can catalyze the U(III) oxidation in acidic aqueous solutions, was reduced to the level lower than 1 ppm (10^–4%). The total purification factor was higher than 103. The purification required 3–4 theoretical plates with HETP of the columns of 35–40 cm.