The book contains an analysis of theoretical dependences, bottlenecks and limiting factors of a new technology used in both Consteel and shaft furnaces operating with flat bath. Performances obtained and potentialities of these furnaces are examined. Based on this analysis, a steel melting aggregate of the new type - fuel arc furnace FAF has been developed and offered. In comparison with the best modern electric arc furnaces of identical capacity the productivity of FAF is higher by 36% and electrical energy consumption is lower by a factor of 1.8. Environment characteristics are considerably improved.