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高纯度镉的制备,一般采用蒸馏法、电解法以及区域熔融等方法.区域熔融可以制得6个九以上的高纯镉,但它要求原料镉的纯度在5个九以上才行.蒸馏法是利用镉易挥发的特性,对除去不易挥发杂质是有较好的效果,但对镉的主要杂质锌,由于两者蒸气压很接近,蒸馏法效果不大.所以用蒸馏法时,原料镉必须先经碱熔除锌,而碱熔导致镉的较多损失.电解法除锌却有较好的效果,因为镉和锌的析出电位相差较大.
The preparation of high-purity cadmium, usually by distillation, electrolysis and regional melting method etc .. Regional melting can be obtained more than nine high-purity cadmium, but it requires the purity of raw materials cadmium in more than five Caixing. Distillation Is the use of cadmium volatile characteristics of the removal of non-volatile impurities are better results, but the main impurities of zinc cadmium, as the two are very close to the vapor pressure, distillation is not effective, so the distillation method, the raw material of cadmium Alkali must be used to remove zinc, while alkali melting leads to more loss of cadmium.Electrolysis has a better effect than removing zinc, because the precipitated potential of cadmium and zinc differ greatly.