What is blast furnace

A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, typically iron. The process involves combining iron ore, coke (a form of carbon derived from coal), and limestone, which are charged into the top of the furnace. Air is blown into the furnace through tuyeres (small openings near the bottom) at high temperatures, usually around 1,600 to 2,200 degrees Fahrenheit (870 to 1,200 degrees Celsius). The components within the furnace react as follows: 1. **Coke combustion**: The coke burns in the presence of air, producing carbon dioxide and generating the heat necessary for the process. 2. **Reduction of iron ore**: The carbon dioxide produced can further react with more coke to form carbon monoxide, which then reacts with the iron ore (mostly iron oxides) to produce molten iron and carbon dioxide. 3. **Limestone's role**: The limestone acts as a flux, helping to remove impurities from the mixture. It combines with impurities to form slag, which floats on top of the molten iron and can be easily removed. The end products of the blast furnace process are molten iron, also known as pig iron, and slag. The pig iron can be further processed in steelmaking or cast into various shapes for different applications. The blast furnace is a crucial part of the integrated steelmaking process and has been a key technology in the iron and steel industry for many years.