Question

Describe the role of iodine in the refining of zirconium.

Answer 1

In metallurgy, the refining process refers to the purification of impure metals. In this process, the end product is chemically identical to the original product but it is purer than the former one. The compound formation process is followed in this process.

Complete step by step answer:
We know that the method in which zirconium is refined and pure zirconium is obtained is called the van Arkel method. It is used in the purification of titanium and zirconium. In this process, impure zirconium is heated in an evacuated vessel with iodine. Impure iodine is heated with iodine to form a volatile compound to form a tetra iodide of zirconium. It is based on the thermal decomposition of the metal components. Further zirconium tetra iodide is obtained as a product. At last, it is heated with a tungsten element to get pure metal. The reactions involved here are as follows:
$Zr + 2{I_2} \to Zr{I_4}$ $Zr + 2{I_2} \to Zr{I_4}$ (at $870$ K)
$Zr{I_4} \to Zr + 2{I_2}$ (at $2076$ K)
This method is based on the fact that metals are converted to their volatile compounds while impurities are not affected during compound formation. Van Arkel is used for getting ultra-pure metal. In this process, the impurities are left behind as they do not react with iodine

Note: In this method, the metal should form a volatile compound with the available reagent. Also, the volatile compound formed should be easily decomposable so that it could be recovered. Also, it is used in the purification of titanium metal.