N O T A T E C N I C A la metallurgia italiana 72 5/2005 Atti Notizie The new VAI FUCHS ultimate EAF: Dawn of a New Era in Electric Steelmaking T. Narholz, B. Villemin Through the combination of advanced electric steelmaking technologies and design features VAI FUCHS is now in a position to offer an electric arc furnace capable of producing approximately 1,800,000 tons of liquid steel per annum. Referred to as the ULTIMATE EAF, this furnace features a tapping weight of 120 tons and an average tap-to- tap time of only 30 minutes. How such a furnace could look, the respective design figures and which technologies are employed is the topic of this paper. INTRODUCTION During the past twenty years electric steelmaking has been the primary driving force behind the growth in the steel indu- stry. Modern EAF-based steelmaking plants feature following main advantages: • Relatively low investment costs com- pared to the integrated blast-furna- ce/oxygen steelmaking route • Utilization of a wide range of raw ma- terials such as scrap, DRI, HBI and hot metal • Ability to fulfill a wide range of pro- duction targets and steel qualities to meet the specific market requirements • Low operational and thus conversion costs, promoting a relatively short re- turn-on-investment. For more than 35 years VAI FUCHS has been a frontrunner in the development of new technologies for electric steel- making. Highlights include the introduc- tion of water-cooled equipment, current- conducting electrode arms, single-point roof lifting, shaft furnaces, twin-shell EAFs and refining combined burner sy- stems for enhancing productivity. Inno- vation has always been a trademark of the company philosophy. To date, VAI FUCHS has supplied more that 100 elec- tric arc furnaces of AC and DC design, in- cluding shaft furnaces for scrap pre-hea- ting and twin-shell EAF installations. As a result of their continued emphasis on research and development and throu- gh the combination of all of their advan- ced technologies and EAF design featu- res VAI FUCHS is now in a position to of- fer a new generation of electric arc fur- naces. Referred to as the ULTIMATE se- ries, a single EAF vessel with a tapping weight of 120 ton and an average tap- to- tap time of about 30 minutes is now capable of producing approximately 1,800,000 tons of steel per annum. The possibility of previously unattained pro- ductivity levels at record-low conversion costs now opens the door to a new era in electric steelmaking. A general view of an ULTIMATE EAF can be seen in Figure 1. PLANT DESIGN General The new ULTIMATE EAF has been desi- gned by VAI FUCHS on the basis of ex- tensive know-how and plant-building ex- perience in electric steelmaking. In addi- tion to changes in the basic design of the EAF, a number of additional improve- ments were carried out in connection with the mechanical equipment, power supply, water-cooled parts, robotic sy- stems, measurement units, oxygen- and carbon-injection systems, process con- trol, automation as well as on dedusting and environmental equipment. Overall plant logistics were also reviewed to avoid operational bottlenecks, to perfec- tly match the capacities of all EAF-rela- ted facilities and systems with each other, and to ensure an optimized pro- duction route for achieving the designed production targets. On the basis of detailed calculations in combination with the results from va- rious operating plants the main design features of this new furnace type can be summarized in Table 1. T. Narholz, B. Villemin VAI FUCHS GmbH, Germany Figure 1: General View of a VAI FUCHS ULTIMATE Electric Arc Furnace. Tapping weight . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .120 t Hot heel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40 t Tapping temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1,620 °C 1 Scrap bucket . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .130 t Yield . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90% Scrap density . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .0.8 t/m 3 EOEBT* design . . . . . . . . . . . . . . . . . . . . . . . . . . . . .for Ø of 7.2 m Total panel length . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.4 m Roof height . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1.5 m 4 RCBs (O 2 and C injection) . . . . . . . . . . . . . . . . . . . .2,500 Nm 3 /h 3.6 MW 2 Burners . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3.6 MW 3 PC** injectors (O 2 ) . . . . . . . . . . . . . . . . . . . . . . . . . . .400 Nm 3 /h 3 Carbon injectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70 kg/min *EOEBT = Energy-Optimized Eccentric Bottom Tapping ** PC = Postcombustion Table 1: Key Data of a 120-t ULTIMATE EAF.