Abstract: To directly and clearly observe the state inside a melting chamber in an electric furnace, a video-device-equipped electric furnace comprises: a melting chamber; a preheating chamber; and a video device to observe an inside of the melting chamber. The video device includes: a relay lens; an inner tube containing the relay lens and having an outer diameter of 100 mm or less; an outer tube containing the inner tube; and an imaging device located at an axial end of the relay lens on a furnace outside. The video device is provided through a hole in a furnace wall or lid so that the relay lens is located 300 mm to 3500 mm away from a highest molten iron interface in a vertically upward direction and the imaging device is located 300 mm or more away from an inner wall of the furnace wall or lid in a furnace outward direction.

Abstract: To ensure stable supply of a cold iron source to a melting chamber, a method of producing molten iron uses an electric furnace that includes: a preheating chamber; a melting chamber; an extruder located in the preheating chamber; and a video device configured to observe an inside of the melting chamber, and comprises: an extrusion process of supplying a cold iron source preheated in the preheating chamber to the melting chamber by the extruder; and a melting process of melting the cold iron source supplied to the melting chamber by arc heat to obtain molten iron, wherein in the extrusion process, a moving amount of the extruder and/or a time interval for moving the extruder is controlled based on visual information obtained from the video device.

Abstract: A steel continuous casting method using a continuous caster that includes a pair of upper magnetic poles and a pair of lower magnetic poles is disclosed. The method comprises braking a molten steel flow with DC magnetic fields respectively applied to a pair of upper magnetic poles and a pair of lower magnetic poles while stirring the molten steel with an AC magnetic field simultaneously applied to the pair of upper magnetic poles, the strength of an AC magnetic field applied to the upper magnetic poles and strengths of DC magnetic fields applied to the upper magnetic poles and the lower magnetic poles are controlled within a particular ranges in accordance with the width of a slab to be cast.

Abstract: A steel continuous casting method using a continuous caster that includes a pair of upper magnetic poles and a pair of lower magnetic poles is disclosed. The method comprises braking a molten steel flow with DC magnetic fields respectively applied to a pair of upper magnetic poles and a pair of lower magnetic poles while stirring the molten steel with an AC magnetic field simultaneously applied to the pair of upper magnetic poles, the strength of an AC magnetic field applied to the upper magnetic poles and strengths of DC magnetic fields applied to the upper magnetic poles and the lower magnetic poles are controlled within a particular ranges in accordance with the width of a slab to be cast.