In early November, 2010, Siemens VAI Metals Technologies started up the LD (BOF) converter and continuous slab caster of the second production line of the ThyssenKrupp CSA Siderùrgica do Atlântico steel mill.
The first slab had already been cast on the first line in September. The steel works is designed to produce some five million tons of slabs per annum. Siemens VAI supplied two basic oxygen furnace plants, secondary metallurgical facilities, primary and secondary dust-cleaning systems, two continuous slab casters, and the associated electrical and automation equipment.
Dr. Eichelkraut, CEO of ThyssenKrupp CSA, said: “The efficiency and safety of the plant configuration is impressive. Even the slabs produced immediately after commissioning were already of extraordinarily high quality.”
The steel mill is located in Sepetiba in state of Rio de Janeiro. Steel is produced in two 330-ton LD (BOF) converters. These are equipped with the maintenance-free ConLink vessel-suspension systems, quick-change oxygen lances, pneumatic slag stoppers, sublances and bottom-stirring systems. The secondary metallurgical plant includes two ladle-blowing stands for steel homogenization, a chemical-heating stand, and an RH vacuum-degassing plant. The RH tank has a combined oxygen-blowing (COB) lance for decarburization and precise adjustment of the steel quality. A dry-type primary dust-cleaning system was used here for the first time in South America. It is designed to recover and clean 282,600 Nm3 of converter offgas per hour. The waste heat from the converter offgas is also used to generate steam in a boiler plant. The secondary dust-cleaning system has a capacity of more than 2.2 million m3/h.
Slabs with widths of 800 mm to 2000 mm, thicknesses of 200 mm to 260 mm and lengths from 6 to 12 m can be cast on the slab casters. A number of technological packages optimize the production process and ensure that the required product quality requirements are met. The technological packages include: LevCon automatic mold-level control; DynaWidth for online adjustments of the slab width; the MoldExpert system for the monitoring of strand-shell friction and automatic breakout prevention; and the DynaFlex mold oscillator for flexible setting of the oscillation parameters. Easy-to-maintain Smart segments are used in the straightening zone and the horizontal section of the slab caster. Intermediately supported strand rollers ensure a long service life. The Dynacs secondary cooling system provides optimum slab cooling, and the VAI-Q system is the basis for quality assurance. Siemens VAI also installed the automation and process-control system for the slab casters. This enables all operating parameters to be optimally harmonized throughout the entire production process. The entire plant ran in the fully-automatic mode right from the first cast.
The new steel mill of ThyssenKrupp CSA is a highly efficient production facility located near Brazilian iron ore deposits. Around 40% of the produced slabs are to be rolled at German locations of ThyssenKrupp. The remaining 60% are foreseen for further processing at the new ThyssenKrupp works in Calvert, Alabama, U.S.A.