To efficiently collect dust being generated in charging iron scrap by drying/charging the iron scrap in and into a mixer with a groove-type induction heating device without using an overhead crane.

Iron scrap drying ducts 7A-7C are connected to the upper part of iron scrap throwing ports 8A-8C of a mixer 15 with a groove-type induction heating device 9, and a dust collection duct 1 is connected to the upper part of the iron scrap drying duct. In the iron scrap drying ducts 7A-7C, a grate 11 is provided, where the throttle holds iron scrap 10, at the same time, can be charged into the furnace with a desired opening, and can be opened and closed freely. Furthermore, the iron scrap drying duct is provided with a basket conveyer 2, where the basket conveyer moves along the mixer 15 and supplies the iron scrap 10 to the drying ducts 7A-7C. The iron scrap 10 is dumped to the basket conveyer 2 at an iron scrap charging port 5, is subjected to traction by the basket conveyer 2, and is charged into the drying ducts 7A-7C. In the drying ducts 7A-7C, the iron scrap 10 is retained on the grate 11, water is dried for eliminating, the opening is adjusted corresponding to the temperature of molten pig iron 16 for opening the throttle 11, and the amount of charge is controlled for charging the iron scrap 10.