Steel is Made: a Brief Summary of a Blast Furnace:
There are two types
of metals, ferrous & non-ferrous. Ferrous comes from, or contains iron, while
Non-Ferrous does not contain iron.
Some examples of ferrous metals would
be mild steel, cast iron, high strength steel, and tool steels.
of non-ferrous metals would be copper, aluminum, magnesium, titanium, etc.
make steel, iron ore is first mined from the ground. It is then smelted in blast
furnaces where the impurities are removed and carbon is added. In fact, a very
simple definition of steel is "iron alloyed with carbon, usually less than
The following text is taken from the Structural Manual For Ironworkers
Manual V-Volume I.
Blast furnaces require many auxiliary facilities to
support their operations. However, in simplest terms, the furnace itself is a
huge steel shell almost cylindrical in shape and lined with heat-resistant brick.
Once started, or "blown-in," the furnace operates continuously until
the refractory lining needs renewal or until demand for iron drops to the point
where the furnace is closed down. The duration of furnace operations from start
to finish is referred to as a "campaign" and may last several years.
Iron ore and other iron bearing materials, coke and limestone are charged
into the furnace from the top and work their way down, becoming hotter as they
sink in the body of the furnace which is called the stack. In the top half of
the furnace, gas from burning coke removes a great deal of oxygen from the iron
ore. About halfway down, limestone begins to react with impurities in the ore
and the coke to form a slag.
Ash from the coke is absorbed by the slag.
Some silica in the ore is reduced to silicon and dissolves in the iron as does
some carbon in the coke. At the bottom of the furnace where temperatures rise
well over 3000 Fahrenheit, molten slag floats on a pool of molten iron which is
four or five feet deep. Because the slag floats on top of the iron it is possible
to drain it off through a slag notch in the furnace. The molten iron is released
from the hearth of the furnace through a tap hole. The tapping of iron and slag
is the major factor permitting additional materials to be charged at the furnace
This brief summary of the complex operations of a blast furnace is
presented here to provide a point of reference for the actual flow of operations.
Very often, several blast furnaces may be arranged in a single plant so that the
most efficient possible use can be made of fuels, internal rail facilities, etc.
A great site for how steel is made