HANDLING OF SCRAPS AND SCRAP SUBSTITUTES IN MINIMILL

摘要

In the electric steel-making process, raw materials are very important in the three aspects of productivity, cost and quality. In addition, recently many steelmakers have been emphasizing the importance of the scrap in a view of recycling and energy savings because a lot of energy is needed to melt scrap and the resources like scrap are not sufficient. In order to minimize the energy consumption and to improve productivity, cost and quality, steelmakers have been developingnew technologies to use the raw materials effectively. In case of POSCO's minimill, there are tenkinds of scraps and scarp substitutes. Following the improvements ofitspower rate and productivity, the EAFhas been demanding the increasing needs of using scrap substitutes such as hot briquetted iron, pig iron, hot metal and so on. Each of these substitutes has advantages or handicaps in terms ofmetal yield and energy needed. Minimill used the Home and Purchased scrap like Return Scrap, Hot-Metal, P&S grade and BIetc. Because the Minimillis operated within the integrated steelworks, 20 percent to 50 percent of hot metal can be used in the Mini-mill and integrated steel manufacturingprocesses. For example, when the converters of steelmaking plant are in maintenance, Minimill can use that surplus hot metal. Therefore, the blast furnace is independent from the next processes.