Abstract: With computer simulation, the effective separation coefficient in the extraction separation Process for three rare-earth system has been studied. For separation of (A,B)from C, it is found that the effective separation coefficient β_A+B^C has a minimum value, β^* in the extraction section, which is inversely proportional to the total extraction ratio EM. For separation of A from (B,C), β_A^B+C has a minimum value, β^*1 in the stripping scetion, which is directly Proportional to the total extraction ratio E_M*^t. It is also found that β^*(or β(_*′) in good linear relation with total extraction ratio and logarithm of the outlet product ratio, β_cal^*=k₁+k₂E_M+k₃InA₁/B₁ β_cal^*=k′₁+k′₂E′_M+k′₃In_BN^C_N Based on the theory of counter current extraction, a method is developed in whichcthe effective separation coefficient is used to determine the parameter of the extraction separation process for three rare-earth system.

Key words: Extraction separation, Rare earth, Computer simulation