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.

Disclosed is a method for preparing a titanium-containing ultra-low-carbon steel, comprising molten iron pretreatment, converter primary smelting, vacuum refining, continuous casting, hot rolling, pickling, and cold rolling. After vacuum refining decarbonization is finished, the content of free oxygen in molten steel is 100-350 ppm; after Al is then added for deoxidation treatment, the circulation time of the molten steel is greater than or equal to 3 min; after other alloys and rare earth elements are then added to the molten steel to adjust the components of the molten steel to the specifications of a finished product, the circulation time of the molten steel is greater than or equal to 2 min; and finally, an oxide Re.sub.2O.sub.3.Math.Al.sub.2O.sub.3 is generated in the molten steel, and the vacuum refining is finished. The method can effectively improve the properties of a deoxidation inclusion in steel, solve the problem of smooth running of casting of the molten steel, reduce the incidence of cold rolling defects caused by Al.sub.2O.sub.3, and improve the product quality of the titanium-containing ultra-low-carbon steel.

Disclosed is a method for preparing a titanium-containing ultra-low-carbon steel, comprising molten iron pretreatment, converter primary smelting, vacuum refining, continuous casting, hot rolling, pickling, and cold rolling. After vacuum refining decarbonization is finished, the content of free oxygen in molten steel is 100-350 ppm; after Al is then added for deoxidation treatment, the circulation time of the molten steel is greater than or equal to 3 min; after other alloys and rare earth elements are then added to the molten steel to adjust the components of the molten steel to the specifications of a finished product, the circulation time of the molten steel is greater than or equal to 2 min; and finally, an oxide Re.sub.2O.sub.3.Math.Al.sub.2O.sub.3 is generated in the molten steel, and the vacuum refining is finished. The method can effectively improve the properties of a deoxidation inclusion in steel, solve the problem of smooth running of casting of the molten steel, reduce the incidence of cold rolling defects caused by Al.sub.2O.sub.3, and improve the product quality of the titanium-containing ultra-low-carbon steel.

A method for refining molten iron that can stably produce low-nitrogen steel is proposed. In this method for refining molten iron, untreated molten iron with a carbon concentration [C].sub.i between 0.5 mass % and 3.0 mass %, both inclusive, is placed into a vessel, and oxygen is blown onto the untreated molten iron under atmospheric pressure while a hydrogen gas, a hydrocarbon gas, or a mixture gas of these gases is blown in to perform a decarburization and denitrification treatment of the untreated molten iron. It is preferable, for example, that a nitrogen concentration [N].sub.f in treated molten iron after being subjected to the decarburization and denitrification treatment be 30 mass ppm or lower; that treated molten iron after being subjected to the decarburization and denitrification treatment be further subjected to a vacuum degassing treatment; that the untreated molten iron include molten iron obtained by melting a cold iron source; that the untreated molten iron be a mixture of primary molten iron obtained by melting a cold iron source in a melting furnace and molten pig iron having a carbon concentration of 2.0 mass % or higher; that the cold iron source include reduced iron; and that the vessel be a converter.

The instant invention relates to a blow lance assembly for metal manufacturing and refining, developed so as to control slag formation and oxidation, as well as the heat capacity of the reactor, and the conservation of the operational conditions during charging and blowing, having, in its lower part, two groups of gas outlets which determine two blowing conditions, the first group consisting of oxygen passage nozzles having a converging-diverging shape, main responsible for the oxidation reactions and for the conveyance of the basic solid material, mainly calcium oxide, for initial slag formation, and dephosphorization at the final stages during batch refining; the second group consisting of secondary jets with various functions during each blowing stage, the first function, at the beginning of the process as an afterburning agent, through the reaction of oxygen with carbon monoxide generated by the main jets, and the second function being that of accelerating the reaction with carbon by increasing oxygen jet speed, accelerating scrap melting in the early stages and, finally, incrementing the oxidation of the elements of the metal bath, iron, in order to reduce the phosphorus content in the final stages of batch refining.

The instant invention relates to a blow lance assembly for metal manufacturing and refining, developed so as to control slag formation and oxidation, as well as the heat capacity of the reactor, and the conservation of the operational conditions during charging and blowing, having, in its lower part, two groups of gas outlets which determine two blowing conditions, the first group consisting of oxygen passage nozzles having a converging-diverging shape, main responsible for the oxidation reactions and for the conveyance of the basic solid material, mainly calcium oxide, for initial slag formation, and dephosphorization at the final stages during batch refining; the second group consisting of secondary jets with various functions during each blowing stage, the first function, at the beginning of the process as an afterburning agent, through the reaction of oxygen with carbon monoxide generated by the main jets, and the second function being that of accelerating the reaction with carbon by increasing oxygen jet speed, accelerating scrap melting in the early stages and, finally, incrementing the oxidation of the elements of the metal bath, iron, in order to reduce the phosphorus content in the final stages of batch refining.

A converter bottom blowing system comprises a first gas source connected in parallel with a lime powder silo, a lime powder blowing tank and a first injector, where a first cut-off valve is arranged between the lime powder blowing tank and the first injector; a second gas source connected in parallel with the biochar powder silo, the biochar powder blowing tank and the second injector, where a second cut-off valve is arranged between the biochar powder blowing tank and the second injector; a converter, where a plurality of bottom blowing lances are arrayed at a bottom of a converter, the bottom blowing lances are connected with the first injector and the second injector through a three-way valve, a third cut-off valve is arranged between the first injector and the three-way valve, and a fourth cut-off valve is arranged between the second injector and the three-way valve.

An oxygen blowing lance comprising: a lance body including an oxygen conduit and cooling water inlet and outlet conduits surrounding said oxygen conduit; a lance head connected to said lance body and comprising a nozzle body, said nozzle body including a central strut having bore hole, a plurality of nozzles arranged about said central strut, and a plurality of cooling chambers arranged about said central strut, wherein said plurality of nozzles are in fluid communication with said oxygen conduit for discharging oxygen from said oxygen conduit onto a metal bath in a converter vessel, and wherein said plurality of cooling chambers are in fluid communication with said cooling water inlet and outlet conduits; a temperature probe or 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; signal lines connected to said temperature probe for conveying signals from said temperature probe whereby operation of said blowing lance is regulated in response to said signals; and a protective pipe pressurized with a gas disposed in the bore and surrounding said temperature probe assembly and the signal lines.

A method for refining hot metal in a converter using a top-blowing lance having a refining powder supply channel, a combustion oxidizing gas supply channel, and a refining oxidizing gas supply channel that are separate from each other includes supplying at least one of a lime-based flux, iron oxide, and a combustible material as a refining powder from the refining powder supply channel to a surface of the hot metal using a fuel gas or a mixture of the fuel gas and an inert gas as a carrier gas while supplying a combustion oxidizing gas from the combustion oxidizing gas supply channel to form a flame below a leading end of the top-blowing lance, and supplying a refining oxidizing gas from the refining oxidizing gas supply channel to the surface of the hot metal.

A method for refining hot metal in a converter using a top-blowing lance having a refining powder supply channel, a combustion oxidizing gas supply channel, and a refining oxidizing gas supply channel that are separate from each other includes supplying at least one of a lime-based flux, iron oxide, and a combustible material as a refining powder from the refining powder supply channel to a surface of the hot metal using a fuel gas or a mixture of the fuel gas and an inert gas as a carrier gas while supplying a combustion oxidizing gas from the combustion oxidizing gas supply channel to form a flame below a leading end of the top-blowing lance, and supplying a refining oxidizing gas from the refining oxidizing gas supply channel to the surface of the hot metal.