Extraction of aluminium from alumina by Hall-Heroult's Process

Metallurgy (10)

Answer the following questions based on the extraction of aluminium from alumina by Hall-Heroult’s Process:

  1. What is the function of cryolite used along with alumina as the electrolyte?
  2. Why is powdered coke sprinkled on top of the electrolyte?
  3. Name the electrode, from which aluminium is collected.

Answer

(i) Cryolite reduces the fusion temperature of the mixture / Cryolite increases the mobility of the ions / increases the        conductivity of the electrolyte / Acts as solvent for alumina.

(ii) Powdered coke protects the graphite rods of the anode from oxidation by oxygen released at the anode / Powdered coke prevents the loss of heat from the electrolyte.

(iii) Cathode

  • Exam Year: 2019