ENVIRONMENT AND SUSTAINABILITY HEADLINESEnvironment and Sustainability
ThyssenKrupp Nirosta Invests in Eco-Friendly Converter Upgrade
Aug. 10, 2009 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 this spring in the meltshop and was recently granted an official operating license following completion of the ramp-up phase. The modernization featured the installation of two new AOD (Argon Oxygen Decarburization) converters with change vessel and ancillary equipment that 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,” said 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, carbon-rich primary heats produced in an electric arc furnace are further processed in special converters such as the AOD are used to make the stainless steel. The molten metal from the EAF is poured into the converter and oxygen or a mixture of oxygen and other gases such as nitrogen or argon are 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 carbon-rich 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,” said Behmenburg. “At the same time, the sustainable optimization has laid the foundations for greater operating reliability and enhanced flexibility in the melting process.”