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How is petroleum coke used in aluminum production?

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Aerial view of an oil refinery complex near New Orleans, Louisiana, with storage tanks, industrial structures, and smoke rising from the facility, surrounded by open land. — petroleum refining Aerial view of an oil refinery near New Orleans.

In the context of petroleum refining and chemical engineering, petroleum coke is a solid carbonaceous byproduct of severe thermal cracking, a process used to convert heavy residual oils into lighter, more valuable products.1

In the aluminum industry, high-quality, low-sulfur petroleum coke is primarily used to manufacture electrodes for the Hall-Héroult process. During this electrolytic smelting process, these carbon anodes are essential for conducting direct current through the molten cryolite bath. As the alumina is reduced, the carbon anodes are consumed, reacting with oxygen to produce carbon dioxide. Approximately 450 grams of carbon are consumed for every kilogram of aluminum produced. Lower-quality coke that does not meet the specifications for electrode production is typically utilized as fuel, often in combination with coal.123