A process for converting pig iron from a blast furnace
The molten pig iron is loaded into a refractory-lined
tilting furnace, (bessemer converter) at about 125°
C. Air is blown into the furnace from the base and
spiegal is added to introduce the correct amount of
carbon. Impurities (especially silicon, phosphorus
and manganese) are removed by the converter lining
to form a slag. Finally the furnace is tilted so that
the molten steel can be poured off.
In the modern
VLN (very low nitrogen) version of this process, oxygen
and steam are blown into the furnace in place of air
to minimize the absorption of nitrogen from the air
by the steel. The process is named after the British
engineer Sir Henry Bessemer (1813-98) who announced
it in 1856.