Effect of Distribution Coefficient on Copper Purification by Zone Refining Process

It has been generally known that the refining efficiency in zone refining process depends on travel rate, number of pass and distribution coefficient of impurity. In the present study, the effect of distribution coefficient on copper purification was investigated by zone refining process. A numerical model capable of predicting the solute redistribution at any stage of zone refining was proposed. The composition profiles of each segment at the given condition were compared with the results of micro hardness profiles. After zone refining, metallic elements were analyzed by GDOS (Glow Discharge Optical Spectroscopy) and GDMS (Glow Discharge Mass Spectrometry). The impurities Ag, Pb, S and Ti, whose distribution coefficients are below 0.5, were concentrated at the finishing position. Cr, Mn, Si and Zn, whose distribution coefficients are between 0.5 and 1, were distributed irregularly. Fe and Ni, whose distribution coefficients are greater than 1, moved to the starting position. It was found that zone refining process was actually effective to remove impurities whose distribution coefficients are below 0.5. The experimental results agreed well with the simulation result.