Electrolysis: processes – compositions used therein – and methods – Electrolytic synthesis – Utilizing fused bath
Reexamination Certificate
2005-03-15
2005-03-15
Valentine, Donald R. (Department: 1742)
Electrolysis: processes, compositions used therein, and methods
Electrolytic synthesis
Utilizing fused bath
C205S392000
Reexamination Certificate
active
06866767
ABSTRACT:
An improved method is described for adding alumina to a Söderberg or pre-bake type electrolytic cell fed by schedule crust breaking. Instead of adding the full amount of alumina required following each crust breaking, as is traditional, the standard dose of alumina is now split into two smaller doses. Thus, a major proportion, e.g. about 50 to 90% by weight, of the theoretically required alumina to sustain the electrolysis between crust breakings is added following a crust breaking. The electrical resistance of the electrolyte is monitored between crust breakings, and if the resistance begins to rapidly increase indicating the approach of an anode effect, the anodes are activated into a pumping action thereby breaking the crust adjacent the anodes, allowing alumina to flow into the molten electrolyte, and also creating a stirring action within the molten electrolyte. This lowers the resistance such that any anode effect is avoided until the next full crust breaking.
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Desgroseilliers Bernard
Pedneault Guy
Santerre Renaud
Alcan International Limited
Cooper & Dunham LLP
Valentine Donald R.
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