Steel has a unique balance of hardness, flexibility and tensile strength. At the same time it resists shock and tension better than the more brittle cast iron. To make steel, iron ore is heated and melted in furnaces where the impurities are removed and carbon added. Blast furnaces use mainly raw materials iron ore, limestone and coke with some scrap steel to make steel, whereas Electric Arc Furnaces use mainly scrap steel.
The blast furnace was invented by an Englishman named Henry Bessemer in the mid s. Bessemer devised a way of producing steel by blowing air through molten iron to oxidize the material and separate impurities. The modern blast furnace is a large steel shell shaped like a cylinder and lined with heat-resistant brick.
Iron ore, coke and limestone are fed into the furnace from the top and gradually sink down towards the bottom, getting hotter as they descend. In the top half of the furnace, gas from the burning coke releases oxygen from the iron ore. In the bottom half of the furnace, limestone starts to react with the impurities in the ore and coke forming a slag. At the bottom of the furnace, temperatures reach over Fahrenheit. The molten slag floats on top of the molten steel, allowing it to be drained via a slag notch in the furnace.
EAFs are mainly used to produce special quality steels which are alloyed with other metals. EAFs can also be used to produce ordinary, non-alloyed steels.
Visual Impaired. Hearing Impaired. Complete hearing loss. The Making of Steel. Our Value Chain. Tata Steel has undertaken extensive research in making the process of steelmaking more energy-efficient and environmentally sustainable.
Steel has the properties of being strong, applicable in many areas and inexpensive. Therefore, steel is one of the most widely used materials on earth. Since it can be recycled over and over again, it plays a crucial role in man industries. The production of the metal is usually carried out by two different ways: the blast furnace , also known as basic oxygen furnace, or electric arc furnace.
Combinations and variations of both production processes may occur. Steel consists of iron and carbon. However, to influence the properties of the metal, other alloying elements can be added. These include chromium, nickel or aluminum. The coke is cooled and screened into pieces ranging from one inch to four inches. The coke is a porous, hard black rock of concentrated carbon contains 90 to 93 percent carbon , which has some ash and sulfur but compared to raw coal is very strong.
The strong pieces of coke with a high energy value provide permeability, heat and gases which are required to reduce and melt the iron ore, pellets and sinter. The first electric arc furnaces EAFs appeared in the late 19th Century. The EAF uses scrap steel and electricity to produce molten steel.
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