In metallurgy, flux is a substance used to convert:

Which method of purification is represented by the following equations?

$$\begin{gathered} \mathrm{Zn}+2{\mathrm{I}}_{\mathrm{2}}\mathrm{ }\stackrel{875 \mathrm{K}}{\to }{\mathrm{ZrI}}_{\mathrm{4}} \\ {\mathrm{ZrI}}_{\mathrm{4}}\mathrm{ }\underset{\mathrm{Tungsten} \mathrm{filament}}{\stackrel{2075\mathrm{K}}{\to }}\mathrm{Zr} + 2{\mathrm{I}}_{\mathrm{2}} \end{gathered}$$