Purification of Crude Sodium Di-Uranate from Tummalapalle Source, India to Nuclear Grade Ammonium Di-Uranate Using Sulphamic Acid Dissolution Route

Abstract

Crude Sodium Di-Uranate (SDU) from the Tummalapalle mine in India contains 2-3% (w/w) silica, in addition to 5-7% (w/w) organic matter, including polyacrylamides and humic masses, with 2-5% Zirconium (Zr) (w/w) as major impurities. Hence, the direct conversion of SDU to Nuclear Grade (NG) Ammonium Di-Uranate Cake (ADUC) for fuel fabrication via the HNO₃-Tributyl Phosphate (TBP) extraction route is onerous due to silica gel creation. The third phase inception indicates the presence of excess Zr, and micro-emulsion formation confirms that organic matter introduces difficulties in the filtration, recovery, and purification stages. Various analytical techniques, such as X-Ray Diffraction Analysis (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR), and Inductively Coupled Optical Emission Spectrometry (ICP-OES), have been utilized to characterize the raw material (SDU), intermediate products (gel and residues), as well as the final product (NG-ADUC). In this research, an innovative, novel route for the dissolution of SDU employing sulphamic acid (25% w/v) to remove silica, organic matter, and Zr, followed by the conventional route to NG-ADU, eliminates the three major process difficulties, namely (i) gelation, (ii) third phase formation, and (iii) microemulsion formation. In addition, the sulphamic acid-extracted Uranium (U)-bearing stream ultimately achieves 99.5% overall U recovery and produces nuclear-grade U with desirable morphological characteristics.