Extraction of uranium from heap leach liquor with tri-n-octylamine: Equilibrium data and flow-sheet calculations

The recovery of uranium from an acid heap leach liquor has been investigated. Tertiary amines (tri-n-octylamine) have been chosen as extractants because of their high selectivity and efficiency. According to the theory of the mechanism of extraction by amines, an equation has been proposed for the extraction isotherms of uranium. In amine extraction systems the organic-aqueous volume ratio is more important for uranium extraction efficiency than amine concentration. Equilibrium data are further developed according to the McCabe-Thiele approach to calculate from extraction isotherms and stripping isotherms the number of theoretical stages. Three stages and two stages respectively are predicted for extraction and stripping circuits with an over-all uranium recovery of 98.9%.