METHOD OF STEEL MAKING Russian patent published in 2003 - IPC

FIELD: making steels in electric arc steel melting furnaces. SUBSTANCE: proposed method includes making steel in two electric arc steel melting furnaces. Dephosphorization and decarburization of iron poured in first furnace are performed by oxygen blowing at rate of 1000 to 5000 cu m/h at addition of lime and iron ore oxidants at consumption of 1-35 and 1-20 kg/t of steel, respectively. Then, semi-product thus obtained is tapped from first furnace to ladle after attaining required content of carbon; ladle is not fully filled with steel semi-product obtained in second furnace by melting scrap. In tapping steel, furnace slag is cut off and solid slag-forming mixture is added to ladle at consumption of 15 to 20 kg/t; said slag-forming mixture consists of lime, feldspar and alumina at the following ratio: (1.2-1.5): (0.4-0.65) : (0-0.1). After tapping, ladle with steel is delivered to out-of-furnace treatment plant where chemical composition is brought to required level obtained through addition of ferroalloys and master alloys and steel is subjected to desulfurization by blowing it with inert gas at rate of 45-80 cu nm/h in the amount of 0.1-0.5 cu nm/t through porous tuyeres under lime-alumina slags at basicity of 1.5-3.0 and injection of powder-like lime at rate of 0.01- 0.50 kg/t. EFFECT: increased productivity; low cost; improved quality. 1 dwg