Study of scandium sorption on a phosphorus-containing cation exchange resin from solutions generated during uranium extraction

Purpose. This study aims to develop an efficient method for scandium recovery from barren solutions generated during the in-situ leaching of uranium ores, using a phosphorus-containing cation exchange resin, and to determine the optimal sorption conditions. Methods. The research employed static and dynamic sorption techniques and kinetic modeling of ion exchange processes. Elemental analysis was performed using ICP-MS spectrometry following microwave-assisted sample digestion. Gel diffusion coefficients, kinetic parameters of the pseudo-first and pseudo-second order models, and half-exchange times were calculated. The efficiency of the sorption process was assessed across a range of solution acidities (H2SO4 = 5-15 g/dm3). Findings. Phosphorus-containing ion exchange resins with strong complexation properties demonstrated high potential for extracting rare earth elements. Experimental variation of the feed solution pH revealed a significant influence of acidity on scandium uptake. It was found that increasing the solution acidity to 15 g/dm3 resulted in the maximum sorption capacity for scandium (0.384 mg/g), while simultaneously reducing the uptake of impurities. The sorption process followed a pseudo-second-order kinetic model with a high coefficient of determination (R2 = 0.999). Gel-phase diffusion was identified as the rate-limiting step. The calculated half-exchange time was 1884 seconds. Originality. A comprehensive kinetic and phase-chemical study of scandium sorption from uranium-bearing solutions onto a phosphorus-containing cation exchanger has been conducted for the first time. The applicability of the Ho and McKay kinetic model has been confirmed, and key exchange parameters have been determined. Practical implications. The results of this study can be applied in the design and optimization of scandium and other rare earth element recovery processes from leach solutions generated during uranium ore processing, enabling their further use in various industrial sectors.