Chemical Principles Of Ironmaking

Blast furnace production is carried out continuously. The first generation blast furnace (from start-up to major overhaul shutdown) can produce continuously for several years to more than ten years. During production, iron ore, coke, and flux are continuously loaded from the top of the furnace (usually composed of a bell and hopper, while modern blast furnaces have bell valve and bell free tops). Hot air (1000-1300 degrees Celsius) is blown into the lower part of the blast furnace through the tuyere, and fuel such as oil, coal, or natural gas is injected. The iron ore loaded into the blast furnace is mainly a compound of iron and oxygen. At high temperatures, the carbon in the coke and the injection material, as well as the carbon monoxide generated by the combustion of carbon, take away the oxygen from the iron ore to obtain iron. This process is called reduction. Iron ore is refined into pig iron through reduction reactions, and molten iron is released from the iron outlet. The gangue, coke, and ash in the injection material of iron ore combine with the flux such as limestone added to the furnace to form slag, which is discharged from the iron outlet and slag outlet respectively. Gas is exported from the furnace top, and after dust removal, it is used as industrial gas. Modern blast furnaces can also utilize the high pressure at the top of the furnace to generate electricity using a portion of the exported gas.