What is the primary function of a blast furnace?

• A. Separates iron from the oxygen in iron ore
• B. Produces copper
• C. Refines aluminum
• D. Boils water to generate steam

Answer: (A)

The primary function of a blast furnace is to turn iron ore into metallic iron by reducing the iron oxide with carbon monoxide generated from coke. Inside the furnace, iron ore, coke, and limestone are heated to extreme temperatures; the coke burns and produces carbon monoxide, which removes oxygen from the iron oxide, leaving behind molten iron. Impurities combine with limestone to form slag, which floats on the molten iron and is tapped off separately. The result is molten iron (pig iron) that can be refined later to make steel. This is why the blast furnace’s main purpose is to separate iron from the oxygen in its ore, not to produce copper, refine aluminum, or boil water for steam.