Device used to convert molten pig iron to steel, via the
bessemer process. Typically it is made of steel, and lined with either
gannister or
dolomite.
Physically speaking, the
converter is a hollow,
egg-shaped device capable of holding approximately 8 to 30 tons of
pig iron (though the standard
charge is only 15 to 18 tons). There is an opening at the top, which serves as the means by which new
iron is introduced as well as by which refined
steel may be extracted. The bottom contains a number of
perforations (
tuyères) which allow air to be forced into the charge, and the entire device is set on pivot fixtures known as
trunnions.
When receiving the charge, the converter is tilted to accept the
pig iron. It is then turned upright for the "
blow". This is when air is forced through the
tuyères, where it makes contact with the
iron so as to cause many of the impurities to
oxidize (see:
bessemer process). An amount of
carbon monoxide is also burned away. The air then bubbles from the surface of the iron, and the
slag falls to the bottom. At this point the converter is tilted again so as to allow the
refined steel to be poured out. The process takes about 15-20 minutes, depending upon the size of the charge.