b. Ore reduction flow (electrolytic).
(1) Cryolite (a vital ingredient in the reduction of aluminum) and alumina
(the basic raw material of aluminum) are received normally by rail and handled by
conveyor to storage silos between the potline buildings.
(2) The third ingredient in the production of aluminum is carbon, which is
formed into electrodes by a melting and molding process in the carbon electrodes
and paste plant.
The most frequently used source for this process is petroleum
coke, which may either be stored in open stockpiles or in a storage building.
(3) All these ingredients are brought together in the electrolytic furnaces in
the potline buildings.
Cryolite is melted in the furnace by the passage of an
electrical current; alumina is added and oxygen is released when the alumina melts.
The oxygen combines with carbon from the electrodes to form carbon dioxide gas,
which is vented. Molten aluminum is formed, tapped from the furnace, and made into
ingots or pigs in the casting buildings.
Therefore substation facilities and transformer yards will be present.
(4) Cryolite releases fluorine gas during the reduction process.
This is
recovered (fluorine recover) and reused in the synthetic production of cryolite.
The fluorine recovery building is a good indicator of an ore reduction plant
(Figure 2-7).
Figure 2-7.
Ore Reduction Plant (Electrolytic).
IT 0673
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