Removal of Radionuclide Uranium from South China’s Ion-adsorption Rare Earth Leach Liquor Using Solvent Extraction with Naphthenic Acid

Abstract

A novel naphthenic acid extractant has been used to remove U from South China’s ion-adsorption rare earth (RE) leach liquor. The system was optimized in terms of its extractant composition and the conditions for loading, stripping and phase separation. Extraction and stripping distribution isotherms were determined. 99.70% of the U was removed by three-stage counter current extraction using 15% (v/v) naphthenic acid and 15% (v/v) iso-octanol in sulfonated kerosene with an A/O ratio of 1:1 at 27±1°C, while 67.50% of the Fe, 16.53% of the Al, but only 1.71% of the RE were co-extracted, resulting in the separation of U from RE. The loaded metals could be completely removed by three-stage counter current stripping with 5 mol/L HCl with an A/O ratio of 1:10 at 27±1°C, allowing the extractant to be regenerated and recycled. The U--enriched strip liquor contained 164.50 mg/L, facilitating the subsequent precipitation of radioactive pollutants.