To use in common an oxygen feed refining and an arc refining, to recover thermal energy retained in exhaust gas by preheating a solid iron source such as scraps and to melt and refine the solid iron source with high thermal efficiency.

Two furnace casing shells 4 and 5 are arranged in symmetrical positions on a turntable 3. An oxygen feed refining by a large volume of oxygen feeding and water cooling lance 6 from a furnace belly shell 7 with which the furnace casing shell 4 is covered is separated from an arc refining from a graphite electrode 11 disposed on the upper part of a furnace belly shell 8 with which the furnace casing shell 5 is covered. They respectively perform melt and refine half of the solid iron source. The turntable 3 is turned during a refining process to change the position of the lance 6 for the position of the electrode 11, After that, the oxygen feed refining and the arc refining are respectively carried out in the remaining half of the melting and refining process.