Kinetics of uranium and iron dissolution by sulfuric acid from Abu Zeneima ferruginous siltstone, Southwestern Sinai, Egypt

Abstract

This study deals with kinetic studies of uranium and iron dissolution using sulfuric acid from Abu Zeneima ferruginous siltstone, Southwestern Sinai, Egypt. The importance of this study stems from the fact there is a difference in the dissolution rate and activation energy which allows the separation of the two elements from each other through the dissolution units without entering the extraction units. The influence of H2SO4 concentration, temperature, stirring speed, particle diameter and solid to liquid phase ratio was examined. The dissolution rate was greatly influenced by the studied dissolution factors. Kinetic data analysis showed that the dissolution mechanism follows the shrinking core model with chemical reaction as a rate determining step with an activation energy (Ea) of 31.59 kJ/mol for uranium and (Ea) of 26.02 kJ/mol for iron. The dissolution study showed that 0.8 M H2SO4 can dissolute approximately 81.92% of uranium and 96.94% of iron at 90 °C with 400 rpm stirring, 0.074 mm particle diameter and 5/50 g/ml (S/L) phase ratio.