Question

Name the process used for the purification of bauxite.

Answer 1

Bayer's process is used for the purification of bauxite $\left({\mathrm{Al}}_2{\mathrm{O}}_3·2{\mathrm{H}}_2\mathrm{O}\right)$.

• Aluminium is extracted by Bayer's process.
• The bauxite is powdered and mixed with a concentrated solution of caustic soda $\left(\mathrm{NaOH}\right)$ to give sodium meta aluminate and impurities are removed by filtration.
• Chemical reaction: $\underset{\mathrm{bauxite}}{\underbrace{{\mathrm{Al}}_2{\mathrm{O}}_3·2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{s}\right)}}+\underset{\mathrm{caustic}\mathrm{soda}}{\underbrace{2\mathrm{NaOH}\left(\mathrm{aq}\right)}}\stackrel{{150}^{°}}{\to }\underset{\mathrm{sodium}\mathrm{meta}\mathrm{aluminate}}{\underbrace{2{\mathrm{NaAlO}}_2\left(\mathrm{aq}\right)}}+\underset{\mathrm{water}}{3{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}$

So, Bauxite is the process used for the purification of bauxite.