Which method is used for refining $Zr$ and $Ti$? Explain with equations.

(N/A) $Zr$ and $Ti$ are refined by the $Van \ Arkel$ method.
In this process,the impure metal is converted into a volatile metal iodide by heating with iodine.
The metal iodide is then decomposed on a tungsten filament at a high temperature $(1800 \ K)$ to obtain the pure metal.
For $Zr$:
$Zr(s) + 2I_2(g) \rightarrow ZrI_4(g)$
$ZrI_4(g) \xrightarrow{1800 \ K} Zr(s) + 2I_2(g)$
For $Ti$:
$Ti(s) + 2I_2(g) \rightarrow TiI_4(g)$
$TiI_4(g) \xrightarrow{1700 \ K} Ti(s) + 2I_2(g)$