How is Aluminum formed??Thanks!!
I don't think any significant quantity of aluminum is produced by reduction with carbon - aluminum is too reactive for this to give a good yield. Instead, the metal is produced by electrolysis in the Hall-Heroult process. First, aluminum ore is processed to aluminum oxide in the Bayer process. This ore, bauxite, consists of aluminum oxides and hydroxides with some impurities, mostly iron oxides. The aluminum oxide/hydroxides are dissolved with concentrated sodium hydroxide in water. Iron oxides and hydroxides do not dissolve, and are filtered out. AlOOH (insoluble in water) + NaOH + H2O ----- NaAl(OH)4 (soluble in water) Neutralizing or cooling this solution will cause aluminum hydroxide to precipitate out. This is then heated strongly to drive off water and produce aluminum oxide. 2Al(OH)3 ----- Al2O3 + 3H2O This aluminum oxide can be melted and then electrolyzed to make the metal and oxygen gas. However, the melting point of aluminum oxide is very high, so it is dissolved in molten cryolite (Na3AlF6), which has a lower melting point. This is then electrolyzed, and molten aluminum collects at the bottom of the cell (cathode), where it can be drawn off. Because the oxygen that would be formed will attack most metal electrodes, a sacrificial carbon electrode is used for the anode and is oxidized to CO2. Very small amounts of aluminum metal occur in nature - it is usually found in association with fossil fuel deposits (which provide the reduced carbon necessary to reduce aluminum minerals).
