The manufacture of iron and steel is one of the basic industries because iron and steel are used for making machinery, which are necessary for all types of industries. Thus industrial growth of a nation maybe measured by the amount of iron and steel it produces. The raw materials needed for iron and steel making are iron ore, coal, limestone and plenty of water. Smelting of iron ore is done in big blast furnaces, which produce pig Iron. Steel is made by heating pig iron to remove impurities and adding alloy metals like nickel, chromium etc. in small quantities. Modern integrated steel plants combine smelting of iron, making of steel and production of steel products together so that there is considerable saving in operating costs and use of energy.
The sturdy structure of modern industrial world is made of steel. In fact, iron and steel manufacturing is the basic or the key industry for any country. Most of the subsidiary industries, such as automobiles, locomotive, shipbuilding, machine building as and also coke manufacturing and coal-tar chemicals are all directly linked up with the iron and steel industry. In modern age, iron and steel industry acts as a spur to industrial activities in any region. Only those nations, which possess well-developed iron and steel industries, have achieved outstanding industrial progress, great wealth and political power in modern age.
Location of iron and steel industry: The art of making iron was known to man from ancient periods. Charcoal was used to smelt iron ore. As the needs were limited, there were a large number of small plants as iron ores were available in many location. The plants were located near the forests, which provided charcoal by burning the wood. This situation prevailed up to 1800 in Europe, the United States and other countries.
When the use of coke for smelting of iron ore was perfected, steel plants came to be located near the coalfields. The amount of coal needed was much larger than the amount of iron ore used and it was cheaper to transport iron ore to the coalfield. Thus the coalfield areas such as the Midlands in Britain, the Ruhr in Germany and Pittsburgh in the United States developed large iron and steel industries.
Steel Plants may also be located at places easily accessible from coalfields and iron ore centres. Another recent trend in location is to prefer coastal sites. In Britain, Germany and the United States, local supplies of high-grade iron ore is depleted and they have to depend on imported ores. Thus ports, which import iron ores, are ideal locations as coal, limestone and alloy metals could be assembled easily near the ports. New steel plants are located at coastal sites in Britain and Atlantic coast in the United States. Japanese steel plants, which depend on import of iron ore and coke, are located along the coast.
Iron manufacturing: Probably 90 per cent of world's iron is now converted into steel.
Pig Iron: To do this, iron ores are mixed with carbon (coke or charcoal) and limestone, and then smelted ma blast furnace. Nearly 2 tons of coal (i.e. one ton of coke) and half ton of limestone are necessary to smelt one ton of iron-ore. Limestone facilitates the reduction of iron ore. It is called flux. Under great heat, oxygen and other impurities of iron-ore unite with carbon and limestone. This mixture is called slag. Iron being thus freed falls at the bottom of the blast furnace in molten condition and the slag being lighter floats above. The molten iron is then taken out of the furnace by a pipe and placed in rectangular sand moulds. These rectangular castings are Pigs. Pig is the crude iron, which contains about five per cent impurities. Articles made out of pig iron are brittle but they can stand great heat. To reduce brittleness and the percentage of impurities, purer iron scrap is often smelted with iron-ore.
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