What is the principal ore of iron, from which iron is extracted?

Step 1: Analyze the question The question asks for the principal (main) ore from which iron is extracted. An ore is a naturally occurring mineral from which a metal can be extracted economically.

Step 2: Review the options

• A. Calcite is CaCO₃, a calcium carbonate. It is not an iron ore. It is used in the blast furnace as a flux, because it decomposes to CaO, which removes silica impurities as slag.
• B. Bauxite is Al₂O₃·2H₂O, the principal ore of aluminium.
• C. Magnetite is Fe₃O₄. It is an iron ore with a high iron content (about 72%), but it is less abundant than hematite.
• D. Hematite is Fe₂O₃. It is the most abundant and most widely used iron ore, and is the main one fed into the blast furnace.

Step 3: Understand the extraction In the blast furnace, coke burns to form carbon monoxide, which reduces the ore:

Fe₂O₃ + 3CO → 2Fe + 3CO₂

Limestone (calcite) is added to remove impurities: CaCO₃ → CaO + CO₂ CaO + SiO₂ → CaSiO₃ (slag)

Step 4: Answer Hematite, Fe₂O₃, is the principal ore of iron.

Exam tip: Memorize the key ore pairs:

• Iron: Hematite (Fe₂O₃)
• Aluminium: Bauxite
• Zinc: Zinc blende (ZnS)
• Lead: Galena (PbS)
• Tin: Cassiterite (SnO₂)
• Copper: Copper pyrites (CuFeS₂)

Remember "Hematite = Fe" because it is the "red iron ore" (the Greek haima means blood, which refers to its red colour).