Impact of ion concentration on Alamine 336 degradation in uranium solvent extraction processes

Abstract

The degradation of Alamine 336, a critical extractant in uranium solvent extraction (SX) processes, is a significant challenge at the Rossing Uranium Limited (RUL) processing plant. This study investigates the impact of ion concentrations—specifically chloride, nitrate, ferrous, and manganese ions—on the degradation of Alamine 336 in the SX circuit. Through a 2^k-p fractional factorial design, the study evaluates the interactions of these ions, aiming to identify key contributors to solvent degradation. The findings reveal that nitrate and chloride ions are significant predictors of Alamine 336 degradation, with higher concentrations leading to increased solvent breakdown. Manganese and ferrous ions also play a role, with manganese exhibiting an oxidizing effect that exacerbates degradation. The study further identifies nitrosamine formation as a primary degradation product, supporting previous research. By employing regression analysis, the study develops a model to predict Alamine concentration based on ion concentrations, offering a valuable tool for optimizing uranium extraction efficiency and mitigating solvent degradation. These results underscore the importance of maintaining controlled ion concentrations, particularly keeping redox potential below 500 mV, to preserve solvent integrity and enhance the overall sustainability of uranium extraction operations.