The values of conventional standard potentials (E) of metals and alloys are advisable to use for quantitative description of the refining processes of salt and metal melts. A procedure is suggested to estimate the unknown magnitudes of E from the experimental values of distribution and separation coefficients as well as equilibrium constants of exchange reactions in liquid system of metal-salt. The calculation results are presented for bismuth alloys of transuranium metals (Am, Cm, Cf) in fused LiCl.