Production and use of substances GapFill

To produce alumina from its ore, which is called  crude oilzeolitebauxiterutile, the   BayerHall–Héroultcontactelectrolysis process is used. First the ore is crushed to increase its surface area and this is reacted with hot, concentrated   aluminium hydroxideammonium hydroxidepotassium hydroxidesodium hydroxide under high pressure. This results in dissolution of the ore. The slurry then undergoes  electrolysisfiltrationcondensationdiffusion to remove impurities. Subsequently, the solution is cooled and   aluminium hydroxidesodium hydroxidealuminium oxideplatinum is added to the solution to aid precipitation. Aluminium crystallises and the solution is filtered. Lastly, the product is heated to remove water from the compound and externally – this is known as   calcinationprecipitationcondensationsedimentation. 

To extract aluminium from alumina, the   BayerelectrolysiscontactHall–Héroult process is used. First, alumina is dissolved in cryolite at 1000 °C, then   precipitationcalcinationsedimentationelectrolysis is carried out and the aluminium is produced.