(f) Hot stoves.
Next to the blast furnace is a group of three or four
tall, interconnected cylinders called hot stoves (Annotation 10).
Burning gas
heats the firebrick-lined labyrinthine interior of the hot stove.
Once it has
reached a high temperature, fuel is shut off and high pressure air is introduced.
This air picks up heat from the firebrick lining and is routed into the bottom of
the blast furnace where it is directed up through the charge. After approximately
30 minutes, the air flow is shut off and fuel is reintroduced to reheat the unit
while another stove assumes the heating task. Thus, with three to four hot stoves,
a constant supply of super-heated air is assured.
Annotation 13 is a waste gas
stack for the hot stoves.
(g) Blast house.
The high pressure air required by the blast furnace is
supplied by the blast house (Annotation 12).
The long, single-story structure
contains a number of compressors which pump air to the hot stoves through a large
pipe called a blast main (Annotation 11).
(h) Dust catcher, The reduction of iron ore to pig iron results in a
tremendous amount of volatile blast furnace gas and dust particles.
This is
directed out of the blast furnace through the down-comer pipe (Annotation 6) into a
dust catcher (Annotation 7). The gas is turned, expanded, and slowed down in the
large, tank-like dust catcher allowing most of the heavier dust particles to drop
to the bottom.
(i) Gas scrubber.
The exhaust gases move to a gas scrubber, also called
the Cottrell precipitator (Annotation 8).
Here, the waste gas passes through a
series of fine water spray curtains, washing the finer dust particles out of the
gas.
(j) Dorr thickener.
These particles go down into a Dorr thickener
(Annotation 9) where any iron particles are recovered for reprocessing.
The
cleaned gas is then either vented into the atmosphere or stored for later use as a
fuel.
(k) Casting shed. The blast furnace operates continuously, but the iron is
tapped from the bottom every four to six hours. This operation takes place in the
casting shed (Annotation 4), a small shelter that houses the lower section of the
blast furnace. The pig iron is tapped from the furnace into a football-shaped car
called a ladle or submarine car (Annotation 14) for transport to the steel
production area.
(l) Slag dump. Slag is also tapped periodically and transported to a slag
dump in a slag car or slag pot (Annotation 15).
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