Intermediate Topic 690 of 1102 Inorganic Chemistry
Smelting
Reducing metal oxides with carbon in a furnace at high temperature.
In-depth explanation of Smelting
Smelting is a high-temperature process in which a metal oxide is reduced to metal, usually with carbon or carbon monoxide. It is carried out in furnaces such as blast furnaces for iron, where the temperature is high enough to melt the metal and the slag. A flux, such as limestone, combines with gangue and impurities to form a molten slag that is less dense than the metal and can be separated from it. Carbon becomes a more favourable reducing agent than the metal at high temperature, which drives the reduction. Smelting is used for iron, copper, lead and zinc.
Going deeper: Smelting
Key ideas: Smelting reduces the metal oxide with carbon (coke) above the melting point to give molten metal and slag. Example: ZnO + C gives Zn + CO. For Cu, Fe sulfide impurity is converted to FeSiO3 slag using silica, FeO + SiO2 gives FeSiO3. A blast furnace is used for Fe, Pb, and reverberatory furnaces for Cu. Reducing agent options: C, CO, H2, Al, Mg. Carbon is best when delta G for C to CO is more negative than for the metal.
Common mistakes and connections: Students think smelting is just melting; it is chemical reduction with slag formation. Coke is not pure carbon but also gives CO as the actual reducing agent. Matte is the molten Cu2S and FeS mixture. Links to Ellingham diagram, blast furnace and slag chemistry.
Visualization of Smelting
Smelting: a high activation barrier is overcome at furnace temperature while carbon reduces the metal oxide and the slag floats away. The interactive lesson shows this as a live animation or chart.
Worked example and use case
Calcium oxide added as flux combines with silica impurities to form a calcium silicate slag: CaO + SiO2 giving CaSiO3.
Frequently asked questions about Smelting
What is Smelting?
Reducing metal oxides with carbon in a furnace at high temperature.
Is Smelting a beginner, intermediate or advanced topic?
Smelting is a intermediate topic in Inorganic Chemistry. It builds on the vocabulary of beginner topics in this area.
What should I learn before Smelting?
Study these earlier topics in Inorganic Chemistry first: Metallurgy, Ore Concentration, Roasting and Calcination.
What comes after Smelting?
The next topics in Inorganic Chemistry are Ellingham Diagram and Thermite Reaction.
Can I practise Smelting with quizzes?
Yes. The interactive lesson includes a self-check question on Smelting, and the Inorganic Chemistry quiz draws on every topic in this area.
Where Smelting fits in Inorganic Chemistry
Smelting is topic 75 of 113 in Inorganic Chemistry.