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Blast Furnace



Calcinated or roasted ore is then reduced to metallic state by any one of the following way depending upon the type of reducing agent for
Smelting Alumino-thermic reduction Electrolytic reduction

Smelting porcess :

1.It is reduction of metal oxide with carbon or its compound
like CO, CO2, Charcoal etc at high temp
2. Calcinated and roasted ore is mixed with coke and flux (8:4:1) and heated in blast furnace in presence of air supply
3. Reducing agent convert ore in to oxide and flux remove gangue in the form of fusible mass.

What is a Blast Furnace?

The purpose of a blast furnace is to reduce and convert iron oxides into liquid iron called "hot metal".
The blast furnace is a huge, steel stack lined with refractory brick.
Iron ore, coke and limestone are put into the top, and preheated air is blown into the bottom.

Why does Iron have to be extracted in a Blast Furnace?

Iron can be extracted by the blast furnace because it can be displaced by carbon.
This is more efficient method than electrolysis because it is more cost effective

The Method

Three substances are needed to enable to extraction of iron from its ore. The combined mixture is called the charge:
Iron ore, haematite - often contains sand with iron oxide, Fe2O3.
Limestone (calcium carbonate).
Coke - mainly carbon
The charge is placed a giant chimney called a blast furnace. The blast furnace is around 30 metres high and lined with fireproof bricks. Hot air is blasted through the bottom.
A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, usually iron, but also others such as lead or copper. In a blast furnace, fuel, minerals and limestone flow continuously through the top of the furnace, while a blast of hot air (sometimes with oxygen enrichment) is blown into the lower section of the furnace. oven through a series of tubes called nozzles, so that chemical reactions occur throughout the furnace as the material moves down. The end products are usually molten metal and slag phases taken from the bottom, and flue gases exiting the top of the furnace. The downward flow of the ore and the flow in contact with an upward flow of flue gases rich in hot carbon monoxide is a countercurrent chemical exchange and reaction process.

In contrast, air ovens (such as reverberation ovens) are naturally aspirated, usually by the convection of hot gases in a chimney duct. According to this broad definition, bloomeries for iron, tin blowing houses and lead smelting mills would be classified as blast furnaces. However, the term has generally been limited to those used for the smelting of iron ore to produce pig iron, an intermediate material used in the production of commercial iron and steel and the vat furnaces used in combination with sintering plants in smelting basic metals.

The blast furnaces existed in China from about the first century AD and in the west of the High Middle Ages. They range from the region around Namur in Wallonia (Belgium) in the late 15th century, being introduced to England in 1491. The fuel used in these was invariably charcoal. The successful replacement of coke by charcoal is widely attributed to Abraham Darby in 1709. The efficiency of the process was intensified with the practice of preheating the combustion air, patented by James Beaumont Neilson in 1828.
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