Steel is an alloy of iron and carbon containing less than 2% carbon and 1% manganese and small amounts of silicon, phosphorus, sulphur and oxygen. Steel is the world’s most important engineering and construction material. It is used in every aspect of our lives; in cars and construction products,Heavy industry and light industry , cargo ships and etc. steel industry, the business of processing iron ore into steel, which in its simplest form is an iron-carbon alloy, and in some cases, turning that metal into partially finished products or recycling scrap metal into steel. The iron and steel industry is a basis for the development of a number of industries in the global economy: the defense industry, transportation and heavy engineering, energy and construction (including aeronautical and shipping construction). Moreover, the iron and steel industry is closely related to the chemical industry and light industry. It shows that the iron and steel industry has the potential to contribute to the competitiveness of national producers and to the growth of the national economy. The steel industry grew out of the need for stronger and more easily produced metals. Technological advances in steelmaking during the last half of the 19th cent. played a key role in creating modern economies dependent on rails, automobiles, girders, bridges, and a variety of other steel products. It can be recycled over and over again without loss of property. Steel industry is one of the essential industries for the development of any community. In fact, it is really the base for numerous industries that could not have been established without steel industry. The European industrial revolution at the beginning of this century was actually founded on this industry. There are three basic routes to obtain finished steel products: (1) integrated steel production, (2) secondary processing, and (3) direct reduction.
Steel is produced via two main routes: the blast furnace-basic oxygen furnace (BF-BOF) route and electric arc furnace (EAF) route. Variations and combinations of production routes also exist. The key difference between the routes is the type of raw materials they consume. For the BF-BOF route these are predominantly iron ore, coal, and recycled steel, while the EAF route produces steel using mainly recycled steel and electricity. Depending on the plant configuration and availability of recycled steel, other sources of metallic iron such as direct-reduced iron (DRI) or hot metal can also be used in the EAF route.
About 75% of steel is produced using the BF-BOF route. First, iron ores are reduced to iron, also called hot metal or pig iron. Then the iron is converted to steel in the BOF. After casting and rolling, the steel is delivered as coil, plate, sections or bars. Steel made in an EAF uses electricity to melt recycled steel. Additives, such as alloys, are used to adjust to the desired chemical composition. Electrical energy can be supplemented with oxygen injected into the EAF. Downstream process stages, such as casting, reheating and rolling, are similar to those found in the BF-BOF route. About 25% of steel is produced via the EAF route.
Another steelmaking technology, the open hearth furnace (OHF), makes up about 0.4% of global steel production. The OHF process is very energy intensive and is in decline owing to its environmental and economic disadvantages. Check out our publication World Steel in Figures for more information.
Most steel products remain in use for decades before they can be recycled. Therefore, there is not enough recycled steel to meet growing demand using the EAF steelmaking method alone. Demand is met through a combined use of the BF-BOF and EAF production methods. All of these production methods can use recycled steel scrap as an input. Most new steel contains recycled steel. Steel is not a single product. There are more than 3,500 different grades of steel with many different physical, chemical, and environmental properties.Approximately 75% of modern steels have been developed in the past 20 years. If the Eiffel Tower were to be rebuilt today, the engineers would only need one-third of the steel that was originally used. Modern cars are built with new steels that are stronger but up to 35% lighter than in the past. Iron in all its forms (cast iron, steel and rolled metal) is the most used construction material in the modern global economy. It retains the leading place in construction ahead of wood, competing with cement and interacting with it (ferroconcrete), and still competing with new types of constructional materials (polimers, ceramics). For many years, the engineering industry has been using ferrous materials more than any other industry. Global steel consumption is characterized by an upward trend.