INVESTIGATION OF REMOVING CADMIUM AND THALLIUM FROM CRUDE INDIUM BY VACUUM DISTILLATION

摘要

In the traditional method for refining of indium, glycerin-KI and glycerin-NH_4Cl are used as electrolytes to remove Cd and Tl by electrolytic refining, which produces In with a purity of 99.995%. Large quantities of polluted industrial waste water are the result. It is calculated that the saturated vapor pressure of Cd and Tl are between 1～200 Pa, which is much larger than the vapor pressure of In. Thus, the study of removing Cd and Tl was carried out over the temperature range between 700～950 ℃ and pressures between 1～15 Pa. After vacuum distillation the contents of Cd and Tl in crude indium could sharply fall below 1 ppm..