Question

Describe the process of preparation of aluminium

by the electrolysis of alumina​

Answer 1

Answer:

Aluminum is extracted from aluminum oxide by a process called electrolysis. First of all, aluminum oxide needs to be in molten form to extract the aluminum ions. ... Therefore, aluminum oxide is dissolved in molten cryolite. Cryolite is a form of an aluminum compound that has a lower melting point that aluminum oxide.

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Answer 2

The process of preparing Aluminium from alumina via electrolysis is given below:

• Alumina (aluminum oxide) is obtained from Bauxite, the chief ore of Aluminium.
• The electrolysis process is called the Hall-Heroult process.
• In the Hall-Heroult process, alumina is dissolved in molten cryolite and electrolyzed in a molten salt bath.
• The electrolysis temperature is around 940 – 980 °C.
• The melting point of Aluminum oxide is approximately 2072 °C and it is impractical to maintain such high temperatures during electrolyzing.
• Hence, in the Hall-Heroult process, alumina is dissolved in molten synthetic cryolite (Na3AlF6) to lower its melting point to make it easier for electrolysis.
• The cathode and anode electrodes used are Graphite and Fused Coke respectively.
• During electrolysis, a low voltage (under 5 V) direct current at 100-300 kA is passed into the electrolysis mixture.
• Liquid aluminum metal is deposited at the cathode and CO2 is produced from the anode and is emitted out.