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How is coke used to remove oxygen from metal ores?

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A labeled diagram of the periodic table entry for carbon, showing its atomic number 6, symbol C, electron configuration, atomic weight range, solid physical state, hexagonal crystal structure, and weakly acidic oxide properties. Color coding and icons indicate it is a nonmetal, solid at room temperature, with hexagonal structure and weak acidity. — carbon Carbon and its properties.

In the context of metallurgy, coke acts as a vital reducing agent used to extract metals from their ores by removing oxygen. This process, known as smelting, typically occurs in a blast furnace.12

The removal of oxygen occurs through two primary chemical mechanisms involving carbon supplied by the coke:

Indirect Reduction: Near the bottom of the furnace, coke reacts with a blast of preheated air to produce carbon monoxide gas. As this gas rises through the furnace, it reacts with metal oxides (such as iron oxide), stripping away the oxygen to produce metallic iron and carbon dioxide.23
Direct Reduction: At the higher temperatures found in the lower zones of the furnace (the bosh), some remaining metal oxides react directly with the solid carbon in the coke.23

Through these reactions, the oxygen is effectively removed from the ore, allowing the metal to be collected in a molten state at the bottom of the furnace.23