Separation of thorium and uranium by liquid-liquid extraction from mixed aqueous nitric acidic-methanolic solutions

A method is described for the separation of Th and U from each other and from other elements, usually occuring in minerals, by liquid-liquid extraction with Aliquat Nitrate (tricaprylmethyl ammoniumnitrate, 6 vol%) in benzene from a mixed solution of 2.5 M HNO3 and methanol (1:1 volume ratio). Permissible upper concentration ratios of interfering elements, such as Li, Na, K, Mg, Ca, Al, Cu, Co(II), Fe(III), Mn(II), Ti(IV), La(III), U(VI), Cl-, ClO4-, SO42-, PO43-, have been determined. Following the separation, Th has been determined by spectrophotometry using Thorin, and U by fluorometry. Results for yield under varying conditions, together with elemental concentrations in the ppm range for U and Th in minerals, are given. (B.T.)