A top-blowing lance includes a refining oxygen gas blowing nozzle having a plurality of ejection openings through which oxygen gas is blown into an iron bath in a reaction vessel, the ejection openings being disposed along a circular orbit at intervals, and a burner nozzle having an axis coaxial with the central axis of the circular orbit, forming a flame inside the refining oxygen gas blowing nozzle, and having ejection openings for blowing a powder heated by the flame into the iron bath, wherein an indicator A that indicates the positional relationship between the ejection openings of the refining oxygen gas blowing nozzle and the ejection openings of the burner nozzle satisfies the specified conditions.

A method for recycling processing of dust generated in a converter furnace, includes: crushing and drying a cake formed by adding a binder to a slurry containing iron powder-containing dust that is generated at the time of converter blowing and wet-collected to produce a mixed slurry and subjecting the produced mixed slurry to a dehydration treatment in a filter press; accumulating the cake in an accumulation tank; and charging the cake into a converter furnace 10, the crushed product in the accumulation tank 25 is kept at a temperature of less than 90 C. by forcibly passing air into the accumulation tank 25 and charged into a converter furnace according to the converter operation.

An apparatus of adding high vapor pressure magnesium to a steel liquid, includes a magnesium additive device and a tube furnace. The magnesium additive device includes a storage barrel, a conveying pipe, a control valve, and an insertion tube. A method of adding high vapor pressure magnesium to a steel liquid, includes placing the magnesium additive device in the tube furnace, and delivering pure magnesium particles into the storage barrel. When the temperature at the mediate lower position of the conveying pipe is increased to reach a preset value, the control valve is opened to pour the pure magnesium particles into the conveying pipe to form a magnesium vapor, and an argon regulating valve is opened to introduce the argon into the conveying pipe so as to add the magnesium vapor to a steel liquid by carrying of the argon.

A method for manufacturing pig iron in a smelting furnace including a vessel, the method including-the following successive steps: loading DRI product in the vessel, melting the DRI product to form a pig iron layer topped by a slag layer, and injecting a carbon containing material directly in the pig iron layer. It also deals with the manufacturing of steel from the pig iron and an associated electrical smelting furnace.

A method for manufacturing pig iron in an electrical smelting furnace including a vessel, the method including the following successive steps: loading DRI product in the vessel, melting the DRI product to form a pig iron layer topped by a slag layer, and injecting a desulphurizing reagent directly in the pig iron layer. It also deals with the manufacturing of steel from the pig iron and the associated electrical smelting furnace.

A method for manufacturing pig iron in an electrical smelting furnace including a vessel, the method including the following successive steps: loading DRI product in the vessel, melting the DRI product to form a pig iron layer topped by a slag layer and, tapping the pig iron into a ladle, and adding a carbon containing material directly in the pig iron in the runner of at least one of the smelting furnace tap holes. It also deals with the manufacturing of steel from the pig iron and the associated electrical smelting furnace.

Proposed is a technology capable of inexpensively and stably reducing the nitrogen concentration in molten steel within a melting furnace or a refining furnace to a low nitrogen concentration range. Provided is a method for denitrifying molten steel including supplying an oxygen-containing gas and a carbon source carried with a carrier gas to the molten steel charged into a melting furnace or a refining furnace, in which the oxygen-containing gas and the carbon source are simultaneously blown onto the molten steel under a condition that, provided that a triangle XYZ is defined by connecting, in a plan view seen from above, a distal end (point X) of a discharge port of a carbon-source blowpipe; an intersection point (point Y) between an inner wall of the furnace and a line obtained by extending a central axis of a carbon source blowing direction; and a distal end (point Z) of a discharge port of an oxygen-blowing lance, that a point

W is positioned on a side XY that is away from the point X by a distance a length of the side XY, and that an angle) .sub.1() is an angle XZW, an angle .sub.2() of an oxygen-containing-gas blowing direction that is open toward a Y side with respect to a side ZX passing through the distal end (point Z) of the discharge port of the oxygen-blowing lance in the plan view seen from above is a positive value and is the angle .sub.1 or less.