Q. How can we obtain Pure alumina?
Pure alumina is obtained from bauxite ore. Powdered bauxite mineral is heated in a concentrated solution of sodium hydroxide under pressure when alumina and silica get dissolved:
Al203 + 2NaOH + 3H20---------------------------------> 2 NaAI(OH)4
Si02 + 2NaOH ------------------------------------------> Na2Si03 + H20