Making Cast Iron in Cupola Furnace
Cupola Furnace:
Cast Iron is manufactured during a furnace referred to as cupola
furnace. Cupola furnace is cylindrical in shape with an almost uniform diameter
(about 1 meter) and a height of about 5 to six meters. The cylinder has an
inner lining of Refractory Bricks which is given tuyers near rock bottom for
injecting the availability of air blast. The outer shell is made of Steel. The
top of the furnace remains open. The cupola furnace contains a charging door, a
platform and tapping holes for the purpose of blasting the air.
The mixture of Pig Iron, coke, and limestone, known as a charge,
is prepared in correct proportions. Coke is used as fuel and limestone as a
fluxing material. Flux is the material which easily fuses and mixes with
impurities to form a slag, which can be taken through the top of the furnace.
The molten metal in almost pure form is collected at the bottom of the furnace
along with the floating slag. The slag is removed intermittently through the hole
and molten metal taken out through its tap hole. The molten metal taken out are
fed into the molds prepared to get desired shapes. The Iron obtained is
understood as forged iron, and therefore the shapes obtained are called forged
iron castings. The forged iron thus obtained, has 1.7 to 4% of carbon with
small impurities of manganese, phosphorus, silicon, and sulfur.
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