ThyssenKrupp
Nirosta has completely modernized its converter facilities in Krefeld and in
so doing made a further contribution to lowering pollution in the area around
the plant. The optimized equipment started operation in the melt shop in spring
and was recently granted an official operating license following the ramp-up
phase. The two new AOD (Argon Oxygen Decarburization) converters with change
vessel and ancillary equipment provide among other things for cleaner air.
"The converter vessels are now enclosed. The dust and gases arising during
charging or tapping the heat are now collected more effectively," says Harald
Behmenburg, head of operations at the Krefeld steel mill. "The air is
extensively filtered before it is released back into the atmosphere. That
enables us to sustainably reduce diffuse dust emissions." In short: clean air
for the environment. The dust arising during the production process is retained
in the filter system.
In the stainless steel industry, special converters are used to make steel
from a carbon-rich primary heat produced in an electric arc furnace. The molten
metal is poured into the converter and oxygen or a mixture of oxygen and
nitrogen or argon added. In the converter the undesirable carbon in the steel
burns off and passes into the flue gas, while chromium - the element that makes
stainless steel stainless - remains in the molten metal. The flue gas is
extracted and filtered.
ThyssenKrupp Nirosta modernized the equipment in collaboration with plant
engineering contractor Siemens VAI (Erlangen, Linz). "Improved protection of the
environment was an important argument in favor of this measure," says
Behmenburg. "At the same time, the sustainable optimization has laid the
foundations for greater operating reliability and enhanced flexibility in the
melting process."