Production and use of substances GapFill

To produce alumina from its ore, which is called  zeoliterutilecrude oilbauxite, the   BayercontactelectrolysisHall–Héroult process is used. First the ore is crushed to increase its surface area and this is reacted with hot, concentrated   sodium hydroxidealuminium hydroxidepotassium hydroxideammonium hydroxide under high pressure. This results in dissolution of the ore. The slurry then undergoes  electrolysisfiltrationdiffusioncondensation to remove impurities. Subsequently, the solution is cooled and   sodium hydroxidealuminium oxideplatinumaluminium hydroxide 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   sedimentationcondensationprecipitationcalcination. 

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