Question

Describe the three steps involved in the leaching of bauxite to get pure alumina.

Answer 1

Hint:In order to the question, the leaching or extracting of alumina from bauxite ore is done by the Bayer’s Process. First step is to digest the powdered ore with a solution of $NaOH$ and then filtered the impurities, and finally heat the hydrated alumina unless we get the pure alumina.

Complete step-by-step answer:The following three steps of the Bayer’s Process for the leaching or extraction of pure alumina from bauxite are as follows:-
(1.) The bauxite ore, most important ore of aluminium, composed of silica, iron, and titanium dioxide as impurities. Bauxite is concentrated by digesting the powdered ore in a concentrated.Solution of $NaOH$ at $473 - 523k$ and 35bar pressure. $A{l_2}{O_3}$ dissolves in alkali and is leached as Sodium Aluminate leaving Impurities behind.
(2.) After leaching of Sodium aluminate, the solution of Sodium aluminate is filtered for cooling and neutralised by passing $C{O_2}$ gas and hydrated $A{l_2}{O_3}$ is precipitated by seeding.
(3.) And, the final touch to get, by filtereds the hydrated alumina dried and heat it to achieve the pure alumina.

Additional Information: According to Bayer’s Process, from the alkaline solution- the aluminium hydroxide precipitate was crystalline and it could be easily filtered and washed, while that precipitated aluminium hydroxide from acid medium by neutralization was very difficult to wash. According to industries, it is the successful process that replaced the Le Chatelier Process which was earlier used to produce Alumina from Bauxite.

Note:Alumina is used in sunscreens, it sits on top of the skin and can help other natural minerals such as zinc oxide and titanium dioxide to reflect harmful rays like ultraviolet rays.