Minimills Challenge Integrated Mills

摘要

Minimills with thin slab casting have become rivals to those with conventional slab casting. The reasons for this are that the thin slab process is more cost-effective in that less reheating and rolling are required. Other advantages include the replacement of cold rolled band by hot rolled band, plant location, often requiring less transportation and staffing, where minimills often operate with an extremely thin organization. A major advantage for the conventional slab casters has been steel quality, especially in terms of cleanliness and mold powder entrapment. However, this concern has been dramatically reduced for thin slab casters with the introduction of the ABB Electromagnetic Brake (EMBR). Recent results from Handan, China show that the total oxygen content in a thin slab using EMBR is comparable with that of a conventional vertical bending slab without EMBR. These quality improvements coupled with operating cost reductions, for example increased mold life, enable the thin slab casters to compete more effectively with the conventional slab casters. At present, some 60 thin slab strands are in operation or scheduled worldwide, of which about half have been equipped with EMBRs. With the start-up of the Terni CSP plant in Italy, thin slab casting is also used for stainless steels. Within ABB, substantial efforts have been made during the 1990's to understand and optimize the use of EMBR by computer simulations. As the different casting processes create turbulence in the mold, 3-dimensional transient simulations are required. ABB has developed a simulation package (EM Tool) that allows us to run transient simulations within reasonable computer time. A video will be presented showing how steel flow in a thin slab caster with a tapered mold is influenced and calmed down when using the EMBR. This video explains a great deal of the results obtained from thin slab caster installations.