The three basic materials employed in iron and steel making are limestone iron ore and coke. Iron does not arise in a free state in environment, till now it is one of the most abundant elements, making up about five percent of the earth crust in the form of different ores. The principal iron ores are taconite or a black flint like rock, hematite or an iron oxide mineral and limonite or iron oxide containing water. After this is mined, the iron ore is crushed into fine particles, the impurities are removed via different means as like: magnetic separation and it is formed into pallets, briquettes or balls employing water and binders. Normally, pellets are about 65 percent pure iron and 25 millimeter in diameter. The concentrated iron ore is concerned to as beneficiated. Several iron-rich ores are employed directly with no palletizing.
Coke is acquired from special grades of bituminous coal that are heated in vertical coke ovens to temperatures of 1150oC and cooled along with water in quenching towers. Coke has various functions in steel making. Single is to produce the high level of heat needed for chemical reactions to have effect in iron making. Second, it generates carbon monoxide or a reducing gas which is then employed to reduce iron oxide to iron. The chemical via-products of coke are employed in making plastics and chemical compounds. Coke oven gases are employed as fuel for power generations, and for plant operations.
The function of limestone or calcium carbonates is to eliminate impurities from the molten iron. The calcium carbonates react chemically along with impurities, serves as a flux that causes the impurities to melt on a low temperature. The calcium carbonates combines along with the impurities and forms a slag that is light and floats above the molten metal. Slag is consequently removed. Dolmite or an ore of calcium magnesium carbonate is also employed as a flux. The slag is later employed for making cement, glass, fertilizers, building materials, road ballast and rock wool insulation.