Separation of rare earth values by liquid/liquid extraction

A process for the separation of rare earth values from an aqueous solution of the nitrates of at least two rare earth elements, comprising liquid/liquid extracting such aqueous nitrate solution with a liquid organic phase capable of containing high concentrations of the rare earth values which comprises a mixture of different organophosphorus extractants having the formulae (I) and (I'):

• ##STR2## wherein formula (I), R.sub.1, R.sub.2 and R.sub.3, which may be identical or different, are each a hydrogen atom or a substituted or unsubstituted linear or branched chain, or cyclic, saturated or unsaturated hydrocarbon radical, with the proviso that the sum of the carbon atoms of the radicals R.sub.1, R.sub.2 and R.sub.3 is equal to at least 12 carbon atoms;
• and wherein formula (I'), R.sub.4, R.sub.5 and R.sub.6, which may be identical or different, are each a hydrogen atom or a substituted or unsubstituted linear or branched chain, or cyclic, saturated or unsaturated hydrocarbon radical, also with the proviso that the sum of the number of carbon atoms of the radicals R.sub.4, R.sub.5 and R.sub.6 is equal to at least 12 carbon atoms.