Question

Zone refining is a method to obtain:

• A. very high temperature
• B. ultra pure $Al$
• C. ultra pure metals
• D. ultra pure oxides

Answer 1

Answer: (C)

ultra pure metals

Zone refining is based upon fractional crystallization as the impurity prefers to stay in the melt and on solidification only pure metals solidifies on the surface of melt.
In this process solubility of the impurities in the metal in molten and solid states is different.
This process is known as ultra-purification because it results in impurity level decreasing to ppm level.