Abstract: A flame retarder containing a phosphate obtained by reacting a compound represented by the general formula (II): ##STR1## wherein R.sup.1 and R.sup.2 are, the same or different, a straight or branched-chain alkyl group having 1 to 8 carbon atoms, an alkenyl group having 2 to 8 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, an alicyclic hydrocarbon group having 3 to 12 carbon atoms or an aralkyl group having 7 to 12 carbon atoms,with at least one compound represented by the general formula (III): ##STR2## wherein R.sup.3 and R.sup.4 are, the same or different, a hydrogen atom or a straight or branched-chain alkyl group having 1 to 8 carbon atoms.

Abstract: A process for separating Fe(III) from an aqueous solution of metallic salts containing at least Fe(III), comprising: (1) bringing said aqueous solution into contact with an organic extraction solvent containing, as an extractant, an organic phosphinic acid represented by the following general formula to thereby extract at least Fe(III) from the aqueous phase and transfer it into the organic phase; ##STR1## wherein R.sub.1 and R.sub.2 are alkyls, respectively, having carbon number in the range of 1 to 20; the sum of carbon numbers for R.sub.1 and R.sub.2 is in the range of 12 to 36; and R.sub.1 is the same as or different from R.sub.2, and (2) separating the resulting Fe(III) loaded organic phase from said aqueous phase.A process for separating Fe(III) from an organic extraction solvent loaded with at least Fe(III), comprising: (1) bringing said extraction solvent into contact with an aqueous solution of a mineral acid having a low concentration at pH 1.