Introduction to Basic Manufacturing Processes and ... - always yours

104 Introduction to Basic Manufacturing Processes and Workshop Technology
Sm all bell
Top
300°F
Ore
Coke
Limestone
Ore
Coke
Reduction
Large bell
Shell
Refractory
lining
Stack
Heat absorp.
Blast pipe
Tuyere 3000°F
Fusion
Combustion
Molten slag
M olten iron
Cinder
notch
Bosh
Hearth
Top hole
Fig. 6.1 Typical blast furnace
sulfur, phosphorus, manganese, calcium, titanium, aluminum, and magnesium. The amounts
of silicon, phosphorus, and sulfur present will determine the purification process used in the
manufacture of the steel. The output from the furnace in form of pig iron is collected in large
ladles from the tap hole existing at lower portion of furnace. As the coke burns, aided by the
air forced into the furnace, the ore melts and collects in the hearth. As the melting process
proceeds, the entire mass settles and thus makes room for the addition of charges at the top.
While the melting is going on, the limestone forms a slag with the impurities. The second
component which makes up the charge is the coke which is made from coal. Coke must be
dust proof, not too combustible, and strong, since it must support the charge. It supplies the
heat which reduces the ore and melts the iron. The iron picks up carbon from the coke and
impurities from the ore. The amount of carbon picked up by the iron is more than is needed
in the production of steel. The carbon becomes part of the pig iron used in the making of
steel. The control of this carbon during the subsequent processes determines the properties
of the steel. The manufacture of coke from bituminous coal is a distillation process. The
impurities are driven off leaving coke.
The pig iron is then processed for purification work for production of various kinds of
iron and steel in form of ingots (large sections) using different furnaces. Fig 6.2 shows a flow
chart for production of different kinds of iron and steel. The steel ingots can be further
processed in rolling mill or blooming mill to produce different structural shapes and sections
of steel. Fig 6.3 represents the entire process for production of market form of steel supply
of different shapes or sections.
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