The Optimum Method for Converting Sponge Iron to Steel in Arc Furnaces

Abstract

Four different process techniques for the melting of sponge iron in arc furnaces are judged by evaluating oper ating results from a great number of arc furnaces up to 200 tons tap weight. Taking the power consumption and productivity as criterions the Conti melt process, i.e. the continuous melting under liquid bath conditions with overlapping of the melting and refining period, has proven to be the optimum process.By applying this process tech-nique it has been possible to increase the productivity, as compared with allscrap practice, by up to 45% with small and up to 20% with large furnaces. The power consum-ption decreases by up to 15% with small and increases slightly with large furnaces. The mechanism of the change of productivity is explained with the aid of a mathe-matical model by varying the most important parameters. Practical aspects of the Contimelt process such as ques-tions of protecting the refractories, optimum metall-ization of the sponge iron and quality of the steel are discussed as well as the iron yield proving to be at least as high as for all-scrap heats. Among the different charg-ing techniques and devices the continuous roof charging through one or three p7pes seems most recommendable.