Effect of phosphate and ferric ions on the extraction of thorium by 40% tri‐n‐butyl phosphate‐xylene

Abstract The partition coefficient for thorium between a thorium‐rare earth nitrate solution and a 40% v/v mixture of tri‐n‐butyl phosphate and xylene decreases as the phosphate concentration in the aqueous phase increases. The addition of excess of ferric nitrate gives a complex with the phosphate and facilitates the extraction of thorium. Precipitation of phosphate occurs at pH <1 in solutions containing ∼ 15 g./litre of phosphate (asP2O5), but addition of iron prevents precipitation of phosphate at pH <1 in solutions containing up to 44 g./litre of phosphate (as P2O5).