Iron is most widely found in the crust of the earth, in the form of various minerals (oxides, hydrated ores, carbonates, sulphides, silicates and so on). Since prehistoric times, humans have learned to prepare and process these minerals by various washing, crushing and screening operations, by separating the gangue, calcining, sintering and pelletizing, in order to render the ores smeltable and to obtain iron and steel. In historic times, a prosperous iron industry developed in many countries, based on local supplies of ore and the proximity of forests to supply the charcoal for fuel. Early in the 18th century, the discovery that coke could be used in place of charcoal revolutionized the industry, making possible its rapid development as the base on which all other developments of the Industrial Revolution rested. Great advantages accrued to those countries where natural deposits of coal and iron ore lay close together.
The sector of mining engaged in the obtaining of iron ore and in its primary processing—crushing, sorting, concentrating,homogenizing, and agglomerating particles by sintering or pelletizing. The iron industry is the raw-material basis of ferrousmetallurgy. Iron ore has been extracted and iron produced from it since ancient times. Iron industry as a sector of theeconomy began to develop rapidly in the first half of the 18th century in connection with the increased smelting of pig ironand steel.
Steel production at an integrated steel plant involves three basic steps. First, the heat source used to melt iron ore is produced. Next the iron ore is melted in a furnace. Finally, the molten iron is processed to produce steel. These three steps can be done at one facility; however, the fuel source is often purchased from off-site producers.