Intermediate Topic 675 of 1102 Inorganic Chemistry
Blast Furnace
Iron ore is reduced by carbon monoxide generated from coke at high temperature.
In-depth explanation of Blast Furnace
The blast furnace is the main industrial method for extracting iron from oxide ores such as haematite, Fe2O3. Iron ore, coke and limestone are charged at the top, and hot air blown in at the bottom burns the coke to carbon dioxide, which is reduced to carbon monoxide as it rises through the hot coke. Carbon monoxide reduces the iron oxide: Fe2O3 + 3CO giving 2Fe + 3CO2. The limestone forms lime, which combines with silica and alumina impurities to make a slag that floats on the molten iron. The product, pig iron, contains about 4 percent carbon.
Going deeper: Blast Furnace
Key ideas: Raw materials: iron ore (Fe2O3), coke and limestone. Hot air at 1000 C or so. Reactions: C + O2 gives CO2, CO2 + C gives 2CO at the hot zone; Fe2O3 + 3CO gives 2Fe + 3CO2 at about 700 C in the upper furnace. Limestone CaCO3 gives CaO, which combines with SiO2 as CaSiO3 slag, floating on the molten iron. Product is pig iron with about 4 percent carbon.
Common mistakes and connections: Students say coke reduces the ore directly; mostly carbon monoxide does the reduction. Limestone is a flux for removing silica, not for reducing. Slag floats because it is less dense and protects iron from oxidation. Pig iron is brittle, so further refining is needed. Links to Ellingham diagrams, steel and equilibrium of Boudouard reaction.
Visualization of Blast Furnace
Reduction of Fe2O3 by carbon monoxide is overall exothermic, about -25 kJ per mole of Fe2O3, driven also by the entropy of CO2 gas. The interactive lesson shows this as a live animation or chart.
Worked example and use case
In the furnace, Fe2O3 + 3CO gives 2Fe + 3CO2.
Frequently asked questions about Blast Furnace
What is Blast Furnace?
Iron ore is reduced by carbon monoxide generated from coke at high temperature.
Is Blast Furnace a beginner, intermediate or advanced topic?
Blast Furnace is a intermediate topic in Inorganic Chemistry. It builds on the vocabulary of beginner topics in this area.
What should I learn before Blast Furnace?
Study these earlier topics in Inorganic Chemistry first: Catalytic Behavior of Transition Metals, Magnetic Properties of Transition Metals, Iron Chemistry.
What comes after Blast Furnace?
The next topics in Inorganic Chemistry are Steel and Copper Chemistry.
Can I practise Blast Furnace with quizzes?
Yes. The interactive lesson includes a self-check question on Blast Furnace, and the Inorganic Chemistry quiz draws on every topic in this area.
Where Blast Furnace fits in Inorganic Chemistry
Blast Furnace is topic 60 of 113 in Inorganic Chemistry.