Sep 28 2010
Shortly after their colleagues at the nearby Bruckhausen BOF meltshop, the production team at the Beeckerwerth BOF meltshop of ThyssenKrupp Steel Europe in Duisburg now also have reason to celebrate: At 2.37 a.m. last Saturday, September 25, the facility produced its 200 millionth metric ton of crude steel.
To illustrate the scale of the achievement, 200 million tons of steel would be enough in theory to build 2,400 Golden Gate bridges. Heinz Liebig, head of crude steel production at ThyssenKrupp Steel Europe in Duisburg, was delighted: “Without the enormous commitment of our employees over decades this milestone would never have been achieved – I am very proud that our people and our equipment have made this record possible.”
The Duisburg-Beeckerwerth meltshop, which employs 734 people, has a capacity of 5.9 million tons of steel a year with an average heat weight of 265 tons. It was built exactly 48 years ago as an LD meltshop with two converters; a third converter was added in 1971. With the building of the first continuous caster in 1974, some ingot casting capacity was closed. A second continuous caster was put into operation in 1980 and ingot casting was discontinued completely in 1986. In 1987 the meltshop was modernized with a converter gas recovery system and new primary and secondary dust collection systems. At the same time a first steel degassing system was put into operation. A second one began operation in late 2001.
In the Beeckerwerth meltshop, hot metal previously tapped from the Hamborn and Schwelgern blast furnaces and delivered in torpedo ladles is processed in several stages to produce liquid steel of the required quality. Here’s a simplified version of what happens: Hot metal still contains impurities such as silicon, sulfur and phosphorus. The sulfur is removed from the iron in an upstream process. The other impurities are removed in the converter by top-blowing oxygen through a water-cooled lance. This process, which generates temperatures of 2,500 degrees Celsius, is known as refining. To cool the boiling steel, steel scrap is added in quantities of ten to 30 percent of the overall heat weight. The actual blowing process lasts around 18 minutes. When it is tapped into a pouring ladle, the molten steel still has a temperature of 1,650 to 1,720 degrees Celsius. Alloying agents can also be added during tapping. Due to the high quality requirements for the properties of the steel, it has to undergo post-treatment, referred to as secondary metallurgy. The steel is then cast into 255 mm thick and up to 2,400 mm wide slabs on one bow-type and one vertical bending-type continuous caster.