Which of the following chemical is used in the purification of red bauxite by Bayer's process?

NaOH is used as leaching agent in Bayer's processIn this process a suitable reagent [NaOH] is made to react with the ore and impurities can't react with NaOH. In red bauxite the impurity present is Fe2O3. Fe2O3 can't react with NaOH. The NaOH react with Al2O3 and form soluble NaAlO2Al2O3+2NaOH→2NaAlO2+H2O NaAlO2+2H2O→AlOH3↓+NaOH 2AlOH3→∆Al2O3+3H2O