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Products and solutions, 2009-08-07, 11:00 AM

ThyssenKrupp Nirosta invests in eco-friendly converter modernization

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.”

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