The current reline of blast furnace 2 in Duisburg-Schwelgern is being used as an opportunity to modernize a further key facility of ThyssenKrupp Steel Europe: Work has started on revamping one of the continuous casters in Duisburg-Beeckerwerth. It is scheduled to go back into operation in just under eight weeks. The work is being carried out in parallel with the reline of blast furnace 2 in order to minimize production losses. The aim of the modernization of continuous caster 1 is to improve slab quality and widen the product range.
The modernization will involve costs of around 90 million euros. “This is further evidence that despite all the burdens being imposed on us, for example in terms of energy prices, we continue to put our faith in the Duisburg site and are investing in its sustainability,” says Dr. Herbert Eichelkraut, Chief Operating Officer at ThyssenKrupp Steel Europe. “This is an important signal for our employees, but also for our customers and suppliers.”
New gentler, more accurate air-water cooling system
Continuous caster 1 is designed for steel slabs with widths between 1,000 and 2,150 millimeters and a thickness of up to 257 millimeters. The rebuild of the two-strand bow-type caster includes a new ladle turret and an 80-ton tundish including car, the replacement of the casting machine itself and the installation of new measuring systems. A key element of the modernization is a new cooling system. Previously slabs were sprayed with water across their full width. A new air-water cooling technology will permit gentler, more accurate cooling of the hot strand.
In the future it will be possible to switch individual nozzles on and off, so allowing targeted cooling of defined zones across the width of the strand. “Thanks to air-water cooling we will have next to no edge defects in slabs anymore,” explains Dr. Arnd Köfler, Head of Crude Steel at ThyssenKrupp Steel Europe. “This will significantly improve the surface quality of the steel, particularly the higher-strength grades our customers are increasingly requesting.”
The caster is being revamped not just technically but visually as well. The color design of continuous caster 1 is based on the production flow, similar to the orange-red design of blast furnace 8, which has become a Hamborn landmark. The striking colors have a positive impact on working atmosphere and also on safety, drawing attention to hand rails on stairways for example.
Continuous caster 1 in Beeckerwerth has been producing slabs for 40 years
Continuous caster 1 was built in 1974 and has been modernized twice since. The revamp is therefore essential. Alongside this unit there is a second continuous caster in Beeckerwerth and another one in the Bruckhausen plant. The capacity of continuous caster 1 is around 2.3 million tons per year. Since it began operation 40 years ago it has produced more than 80 million tons of steel, enough to build almost 1,100 copies of the Golden Gate Bridge in San Francisco. The two continuous casters in Beeckerwerth provide work for roughly 170 employees. They produce high-quality slabs for special steels, mainly for the auto industry, as well as tinplate for the packaging industry, high-strength steels, skelp and quarto plate.
Continuous casting produces endless strand of steel
After pig iron has been converted into steel in the melt shop it is cast into rectangular strands in the continuous caster. For this the liquid steel is poured into a tundish. From there it flows vertically downwards through a tube into a mold. The mold has the same rectangular shape as the finished slabs and is made of water-cooled copper plates. The strand shell solidifies in the mold but the core is still liquid as the strand exits the mold. Full solidification is achieved by applying water – or a water-air mixture in the case of the modernized continuous caster 1. In the lower part of the caster the hot strand is bent through 90 degrees into a horizontal position and guided onto roller tables. On these the strand is cut into slabs by means of torch cutters.
Rice hulls used in steel production
Strange but true – rice hulls are used in steel production. To prevent the surface of the molten steel in the tundish from giving off too much of its heat, steel workers throw sacks of rice hulls onto the red-hot liquid. The hulls dissolve without leaving any residue but help maintain the temperature of the steel before it flows into the mold.