Oxygen Steelmaking Processes

Abstract

Virtually all of the steel in the United States and the world is produced either in an oxygen steel-making converter such as a BOF, LD, OBM (Q-BOP) etc. or an electric arc furnace (EAF). The only exception are the few remaining open hearth shops and a negligible amount in other processes such as the Energy Optimizing Furnace (EOF). This is understandable since much of the steel-making capacity was built or rebuilt from 1955 to 1975; the BOF and EAF were the best tech-nologies available at the time and were compatible with large blast furnace production and relatively inexpensive scrap. However, these conditions are changing. It may be possible to produce iron economically on a small scale, 0.5 million tons per year, in new processes such as COREX and bath smelting. Steelmakers desire more flexibility to use scrap and hot metal and other forms of iron such as direct reduced iron (DRI) and iron carbide. Therefore, it is of value to re-examine steelmaking options. There is currently a large amount of development work related to the electric arc furnace includ-ing scrap preheating, continuous melting and the use of fossil fuels and hot metal. These are dis-cussed in detail in Chapter 10. In particular electric arc furnaces will use more oxygen to oxidize carbon and for post-combusting CO to CO 2 . The EAF will act more like a BOF using fossil fuel such as carbon in iron or in direct reduced (DRI) products. They will also use more virgin (non scrap) iron such as DRI and liquid hot metal. The alternative steelmaking processes examined in this chapter are those using no electrical energy. Many alternative oxygen steelmaking processes were being developed in the 1970s such as IRSID continuous steelmaking, WORCRA and the Bethlehem continuous process. However, these never were commercialized, in part because most companies invested in conventional oxygen steelmak-ing and no new capacity was required. In recent years, other processes have been developed or pro-posed such as the EOF, the AISI continuous process, iron carbide continuous processes and IFCON. In this chapter, the general principles of process types are examined, selected steelmaking processes are technically evaluated and an economic analysis of selected processes is made. This has been the subject of a 1998 publication and much of this chapter comes from that publication. 1