Components of Blast Furnace

FOUNDATION
Foundation is a massive steel reinforced concrete structures partially embedded below the ground level. It is constructed to withstand the loaded furnace weight that may be as much as 10,000 tones for 2000 tones capacity. It may be 15m in diameter and 6-8m in thickness upon which the bottom of the furnace is placed. The bottom of the furnace is constructed by thick fire bricks.

HEARTH
Hearth is the region of the blast furnace where the melting of the iron ore takes place and the molten metal along with the liquid slag are collected. In the earlier days the fire bricks are used for construction of the hearth to make it more secured and efficient. Carbon blocks are used in the modern blast furnaces. Water cooled copper or steel plates are laid in the side walls to protect the linings from excess heat.

BOSH
Bosh is the zone of intense heat .The top of the bosh has the maximum diameter of the furnace. The bosh is the structure consisting of fire bricks with steel reinforcement constructions. Watercooled copper or steel plates are inserted at regular intervals in the furnace lining of the bosh. This helps to protect the lining against very high temperature. Mantles and columns are other important parts of furnace. The furnace structure above the bosh level is supported on a heavily braced steel ring. This steel ring encircles the furnace at the top of the bosh. This is called the mantle. The mantle is supported by uniformly spaced upright heavy columns. These columns are placed in concrete foundations at the bottom.

TUYERES
Tuyeres are located above the hearth. Through the tuyeres, hot air blasts are blown for fuel combustion. The number of tuyeres varies with the size of the furnace. Usually 10-20 tuyeres are uniformly placed above the hearth.The tuyeres are uniformly located at the top level of the hearth. Hot air blast is blown through the hearth into the furnace through these tuyeres. At the bottom of the hearth few holes are created for removal of molten iron and slag. These holes are closed with clay when the hearth is in operation. These holes are opened when molten metals and slags are taken out from the furnace.

BELL & HOPPER ARRANGEMENT
Bell is the top of the furnace .The Hopper is a cone like structure attached to the top of the furnace with the bell. The bell and hopper arrangement is used for charging the Blast Furnace. The double bell arrangement is still is in use for charging the furnace. This arrangement ensures that charging continues without licking of exhaust gases out of the furnace.