Electrolysis Of Alumina Hall's Process

Electrolysis of Alumina (hall's process):

The pure together with dry out alumina obtained from either of the inwards a higher house processes is fused alongside cryolite, Na3AIF6. This molten majority is electrolysed inwards a steel tank (8 ft x vi ft) lined alongside blocks of carbon which serve equally the cathode (Figure 1.1). The anode is rods of carbon hanging inwards the molten mass.

The resistance of the electrolyte to the electrical flow produces plenty estrus which keeps the majority inwards the molten state. Liquid aluminium obtained at the cathode sinks to the bottom off occasionally. Fresh amounts of bauxite are added when required.

The raw cloth for this procedure is Al2O3 only Na3AlF6 provides AlF3 first. Aluminium trifluoride liberates F2 at the anode which reacts alongside Al2O3 forming ALF3 again. Thus Al2O3 gets consumed inwards the process.

The overall reaction may last shown as:

The liberated oxygen attacks carbon anode forming around CO together with CO2 Therefore, inwards the modified method a mixture of composition, 2ALF3. 6NaF. 3CaF2 is used.

Al metallic produced inwards this method is close 99% pure only contains draw impurities of Fe, Si, Al2O3 etc.