Modern and Efficient Mini Mill Concepts Flexible in Electrical Power Quality, Charging Materials and Meltshop Rolling Mill Connections

by Thomas Huber, Fleischer Martin, Niedermayer Walter, Luigi Giacomini

Publisher - Siemens VAI Metals Technologies GmbH

Category - General Novel

The globalization trends are forcing all the local steel industries towards modern production concepts, in particular for long product Mini Mills. These concepts are developed focusing on flexibility in electrical power quality, in charging materials for the EAF and in different melt shop rolling mill connections. As the largest consumers of electricity in Mini Mills, AC Electric Arc Furnaces are a major cause of system perturbations. Flicker compensation is a critical factor in the implementation of new Mini Mills, especially in locations with weak power grids, which we found increased in the emerging markets. Siemens developed the SVC PLUS system to reduce the voltage disturbances and harmonic distortion, and to improve the power factor at the point of common coupling. The Flicker Reduction ratio is more than 4.5. Moreover latest EAF innovation resulted in Siemens VAI EAF Quantum with its pure flat bath operation with lowest flicker, minimum conversion costs, maximized output and environmental compliance. Scrap quality and limited scrap availability, which increase the scrap prices, push in the direction of high percentage melting of substitutes. In order to cover this market request, Siemens VAI developed such flexible and high productive Mini Mill concepts which use up to 40% of hot metal or up to 100% cold and hot DRI. Current trends in direct connection between melt shop and rolling mill are discussed by means of hot charging of billets and direct rolling, respectively.

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