RECTANGULAR FURNACE DESIGN AND REVOLUTIONARY DC-SLAG CLEANING TECHNOLOGY 237

History of the submerged arc furnace For more than 100 years SMS Demag played a significant role in the development of the submerged arc furnace and electric smelter technology. During the past century, the submerged arc furnace has been one of metallurgy’s most amazing diversified melting units, which has found many applications in over 20 different industrial areas, including ferroalloys, iron, silicon metal, copper, lead, zinc, refractory, titanium oxide, calcium carbide, phosphorus and materials recycling, etc.1 SMS Demag has been developing this technology for more than 100 years and has supplied a diverse market with about 700 furnaces and major furnace components2. Numerous applications were constantly developed serving various users3,4. Such an evolution was possible only because of tremendous efforts in research and development and due to the large range of design solutions. The increasing demand for ferroalloys and de-oxidation agents in steelmaking at the beginning of the 20th century led to the development of the first few furnaces. Demag, for the last two centuries a major supplier for the iron and steel industry, started with the construction of the first submerged arc furnace in 1906. The 1.5 MVA unit was installed in Horst, Ruhr/Germany, for the production of calcium carbide and was successfully commissioned in 1906. The ‘evolution ’ and the major milestones of the technology are shown below: 1906: Reduction furnace (bottom + top electrode) 1913: 6-electrode rectangular reduction furnace 1935: 15 MVA furnace 1951: SAF with rotating gear for Si-metal production 1953: 40 MVA large capacity furnace 1956: Compensated low-inductive high currency line 1957: Copper slag cleaning furnace 1958: Hydraulically controlled electrode column 1959: Large-capacity 60 MVA furnace 1966: Encapsulated electrode column 1967: Large-capacity ferro-, silicon-chromium 1974: Large-capacity silicon metal furnace 1975: Hollow electrode charging system 1982: High capacity FeNi rectangular furnace