A method of operating a BOF bottom stir tuyere having an inner nozzle surrounded by an annular nozzle, including during a hot metal pour phase and a blow phase, flowing an inert gas through both nozzles; during a tap phase, initiating a flow of a first reactant through the inner nozzle and a flow of a second reactant through the annular nozzle, and ceasing the flow of inert gas through the nozzles, wherein the first and second reactants includes fuel and oxidant, respectively, or vice-versa, such that a flame forms as the fuel and oxidant exit the tuyere; during a slag splash phase, continuing the flows of fuel and oxidant to maintain the flame; and after ending the slag splash phase and commencement of another hot metal pour phase, initiating a flow of inert gas through both nozzles and ceasing the flows of the first and second reactants.

A method of operating a BOF bottom stir tuyere having an inner nozzle surrounded by an annular nozzle, including during a hot metal pour phase and a blow phase, flowing an inert gas through both nozzles; during a tap phase, initiating a flow of a first reactant through the inner nozzle and a flow of a second reactant through the annular nozzle, and ceasing the flow of inert gas through the nozzles, wherein the first and second reactants includes fuel and oxidant, respectively, or vice-versa, such that a flame forms as the fuel and oxidant exit the tuyere; during a slag splash phase, continuing the flows of fuel and oxidant to maintain the flame; and after ending the slag splash phase and commencement of another hot metal pour phase, initiating a flow of inert gas through both nozzles and ceasing the flows of the first and second reactants.

A method that, regarding a process of refining molten iron, can increase the thermal margin and the amount of cold iron source to be used. A burner having jetting holes for jetting a fuel and a combustion supporting gas is provided at a leading end part of one lance that top-blows an oxidizing gas to molten iron contained in a converter-type vessel, or at a leading end part of another separate lance. A powdery auxiliary raw material or an auxiliary raw material processed into a powder form that is blown into the molten iron from the one lance or the other lance passes through a flame formed by the burner. This top-blowing lance for a converter is configured to secure a predetermined heating time and powder-fuel ratio. Also, a method for adding an auxiliary raw material and a method for refining of molten iron that use this top-blowing lance.

A method that, regarding a process of refining molten iron, can increase the thermal margin and the amount of cold iron source to be used. A burner having jetting holes for jetting a fuel and a combustion supporting gas is provided at a leading end part of one lance that top-blows an oxidizing gas to molten iron contained in a converter-type vessel, or at a leading end part of another separate lance. A powdery auxiliary raw material or an auxiliary raw material processed into a powder form that is blown into the molten iron from the one lance or the other lance passes through a flame formed by the burner. This top-blowing lance for a converter is configured to secure a predetermined heating time and powder-fuel ratio. Also, a method for adding an auxiliary raw material and a method for refining of molten iron that use this top-blowing lance.

A molten iron refining method having, an auxiliary material, and an oxidizing gas supplied through a top-blowing lance, to a cold iron source and molten pig iron that are contained/fed in a converter-type vessel, and molten iron is subjected to a refining process. A pre-charged cold iron source is charged into the converter-type vessel at an amount not larger than 0.15 times. A furnace-top-added cold iron source that's part or all of the cold iron source and added from a furnace top is fed during the refining process. A burner at a leading end of the top-blowing lance that spray holes through which a fuel and a combustion-supporting gas are ejected. During the refining process, a powdery auxiliary material processed into powder that's part of the auxiliary material is blown in, to pass through a flame formed by the burner.

A molten iron refining method having, an auxiliary material, and an oxidizing gas supplied through a top-blowing lance, to a cold iron source and molten pig iron that are contained/fed in a converter-type vessel, and molten iron is subjected to a refining process. A pre-charged cold iron source is charged into the converter-type vessel at an amount not larger than 0.15 times. A furnace-top-added cold iron source that's part or all of the cold iron source and added from a furnace top is fed during the refining process. A burner at a leading end of the top-blowing lance that spray holes through which a fuel and a combustion-supporting gas are ejected. During the refining process, a powdery auxiliary material processed into powder that's part of the auxiliary material is blown in, to pass through a flame formed by the burner.

A molten iron refining method that prevents a cold iron source from remaining unmelted even under the condition of a high ratio of the cold iron source. An auxiliary material is added, and an oxidizing gas is supplied, to cold iron source and molten pig iron that are contained or fed in converter-type vessel, and molten iron is subjected to refining process. Prior to refining process, a pre-charged cold iron source that is charged all at once into the converter-type vessel before the molten pig iron is charged into the converter-type vessel is charged in an amount not larger than 0.15 times the sum of an amount of the pre-charged cold iron source and a charge amount of the molten pig iron, or is not charged. A furnace-top-added cold iron source that is added from a furnace top of the converter-type vessel is fed into converter-type vessel during refining process.

A molten iron refining method that prevents a cold iron source from remaining unmelted even under the condition of a high ratio of the cold iron source. An auxiliary material is added, and an oxidizing gas is supplied, to cold iron source and molten pig iron that are contained or fed in converter-type vessel, and molten iron is subjected to refining process. Prior to refining process, a pre-charged cold iron source that is charged all at once into the converter-type vessel before the molten pig iron is charged into the converter-type vessel is charged in an amount not larger than 0.15 times the sum of an amount of the pre-charged cold iron source and a charge amount of the molten pig iron, or is not charged. A furnace-top-added cold iron source that is added from a furnace top of the converter-type vessel is fed into converter-type vessel during refining process.

A lance comprising a lance body including a lance head connected to said lance body and comprising a nozzle body having a central strut having bore hole; a camera assembly, such as an optical or infrared camera assembly, received in said bore hole for monitoring the temperature of said lance head or molten heat in which the lance is inserted; and a protective pipe pressurized with a gas disposed in the bore and surrounding said camera assembly.

A lance comprising a lance body including a lance head connected to said lance body and comprising a nozzle body having a central strut having bore hole; a camera assembly, such as an optical or infrared camera assembly, received in said bore hole for monitoring the temperature of said lance head or molten heat in which the lance is inserted; and a protective pipe pressurized with a gas disposed in the bore and surrounding said camera assembly.