Feasibility of Employing the Cooled Finger, a Fractional Crystallization Method for the Purification of Magnesium

摘要

Ultra-high-purity magnesium has gained importance in the electronics and biomedical technological fields positioning it as one of the most valuable pure metals in the market. Due to its high reactivity and unique physical properties, vacuum distillation is the process of choice for its purification. Recently, liquid condensation techniques have improved the product collection and processing, however, the high costs associated with this technology and the removal of impurities with a similar vapor pressure to magnesium, such as zinc, remain a challenge. The feasibility of employing the cooled finger, a fractional crystallization method for the purification of magnesium, is analyzed after its successful implementation on other metals such as germanium and aluminum. The distribution coefficient of the most common impurities in Mg is calculated using FactSage, as a measure of the maximum purification that can be achieved through fractional crystallization. Two series of experiments explore the overall purification of magnesium and its relationship with the cooled finger parameters. In the second experimental series, the individual purification of Al, Ca, Mn, and Zn as four of the most predominant impurities in magnesium are further investigated and compared to previously published results from vacuum distillation. The main challenges of fractional crystallization regarding the enrichment of Ti, Zr, and Mn remain as part of the on-going research.