The primary method to obtain iron from iron ore is through a process called smelting reduction. This complex process involves multiple steps and units, but the core principle is reducing iron oxides present in the ore to metallic iron. Here's a breakdown:
The Smelting Reduction Process
The smelting reduction process utilizes two main units working in tandem:
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Pre-Reduction Unit: Iron ore is heated in this unit. Crucially, reducing gases (primarily carbon monoxide and hydrogen) produced by the second unit are used to partially reduce the iron ore. This means the iron oxides in the ore begin to lose oxygen, getting closer to becoming pure iron.
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Smelter-Gasifier Unit: This is where the magic happens. This unit is supplied with coal and oxygen. The coal acts as the reducing agent (source of carbon), and oxygen facilitates combustion and gasification. Inside this unit:
- Coal reacts with oxygen to produce heat and reducing gases (carbon monoxide, CO, and hydrogen, H2).
- The partially reduced iron ore from the first unit is then smelted. Smelting involves heating the ore to a high temperature where the remaining iron oxides react with the carbon monoxide and hydrogen. These gases remove the remaining oxygen from the iron oxides.
The Chemical Reactions Simplified
The general chemical reaction can be represented as:
Iron Oxide (FeOx) + Carbon Monoxide (CO) --> Iron (Fe) + Carbon Dioxide (CO2)
Or:
Iron Oxide (FeOx) + Hydrogen (H2) --> Iron (Fe) + Water (H2O)
A Step-by-Step Summary
| Step | Description | Unit Involved | Input | Output |
|---|---|---|---|---|
| 1 | Iron ore is heated and partially reduced by reducing gases. | Pre-Reduction Unit | Iron Ore, Reducing Gases (CO, H2) | Partially Reduced Iron Ore |
| 2 | Coal and oxygen are fed into the smelter-gasifier to produce heat and reducing gases. | Smelter-Gasifier | Coal, Oxygen | Heat, Reducing Gases (CO, H2) |
| 3 | The partially reduced iron ore is smelted. Iron oxides react with the reducing gases to produce liquid iron. | Smelter-Gasifier | Partially Reduced Iron Ore, CO, H2 | Liquid Iron, Carbon Dioxide, Water Vapor |
Key Considerations
- Temperature: High temperatures are crucial for the smelting process to occur.
- Reducing Agents: Carbon monoxide and hydrogen are the primary reducing agents in this method.
- Slag Formation: Impurities present in the iron ore react with added materials (flux) to form slag, which is separated from the liquid iron.
In conclusion, iron is extracted from iron ore through smelting reduction, a process involving heating, chemical reactions, and the use of reducing agents to remove oxygen from the iron oxides present in the ore, ultimately yielding liquid iron.
