Definition - What does Blast Furnace mean?
This is a huge metallic container that is mostly made of steel, lined with heat-resistant material (brick), and consists of top and bottom entry points; the bottom has a thick lining since it is the hottest part in the structure. It is used in the processing of iron ores to yield pig iron, ferromanganese, Ferro phosphorus, spiegeleisen, silvery iron, and ferrosilicon in steel manufacturing industries. It is designed with long-lasting lining materials to withstand corrosion caused by:
- The acidity of the formed impurities
- The raw material redox reactions
- The temperatures of the air blast
Corrosionpedia explains Blast Furnace
The main purpose of a blast furnace is to convert the iron ores, mined in the form of hematite or magnetite, to pig iron. The blast furnace is in use after the iron ores have been converted into iron-rich pellets, and the coke and limestone prepared in the considerable amounts.
Inside the blast furnace, the raw materials are charged from the top section entry points as they descend. The air blasts are produced at the bottom to boost the reactions aimed at reducing the iron ores into pure iron. The coke undergoes redox reactions to form carbon monoxide, which is necessary for the reduction of iron ores. The limestone is broken down into calcium oxide, which is used to remove sulfur form the ore.
The iron is reduced further as it approaches the bottom. At the bottom, iron lays as the bottom layer while the slag floats on its surface. The gases produced exit through the upper chamber vents. Carbon blocks are used in modern blast furnaces to provide better corrosion resistance and maintain an improved thermal conductivity.