Zirconium is refined by van Arkel method.
Zirconium is refined using the van Arkel technique. By heating metal in an evacuated vessel with iodine, oxygen and nitrogen present as impurities are eliminated. On a tungsten filament heated to roughly $1800 \mathrm{~K}$, the metal iodide volatilizes and is degraded. On the filament, pure metal is deposited.
$\begin{array}{l}
\underset{\text { (Impure) }}{\mathrm{Zr}}+2 \mathrm{l}_{2} \longrightarrow \mathrm{Zrl}_{4} \\
\mathrm{Zrl}_{4} \longrightarrow \underset{\text { (Pure) }}{\mathrm{Zr}}+2 \mathrm{l}_{2}
\end{array}$