Abstract: A method of decarburizing a molten alloy may generally comprise injecting a first gas comprising at least one of argon, carbon dioxide, and oxygen through a first fluid-conducting portion of a tuyere into the molten alloy below the surface of the molten alloy, and injecting a second gas comprising at least one of argon and carbon dioxide through a second fluid-conducting portion of the tuyere into the molten alloy below the surface of the molten alloy. The tuyere may comprise an inner portion concentrically aligned within an outer portion to define an annulus therebetween. The first gas may be injected through the inner portion, and the second gas may be injected through the annulus.

Abstract: The aim of the invention is to produce stainless steel for all stainless steel products both in the austenitic and the ferritic range, based on liquid pig-iron and FeCr solids, without using a supply of electrical energy. According to the invention, the liquid pig-iron, after being pre-treated in a blast furnace (1), is subjected to a DDD treatment (dephosphorization, desiliconization and desulfuration), is heated, finished or alloyed and deoxidated. The quantity of slag-free liquid pig-iron that has been pre-treated in the blast furnace (1) is separated and introduced into two classic “twin” AOD-L converters (2, 3), where the required chemical process steps (of the DDD treatment and of the heating, decarburization and alloying stages) take place in parallel contrary processes using autogenous chemical energy, the DDD treatment being carried out first in the first twin AOD-L converter (2) and the decarburization being carried out first in the second twin AOD-L converter (3).

Abstract: The aim of the invention is to produce stainless steel for all stainless steel products both in the austenitic and the ferritic range, based on liquid pig-iron and FeCr solids, without using a supply of electrical energy. According to the invention, the liquid pig-iron, after being pre-treated in a blast furnace (1), is subjected to a DDD treatment (dephosphorization, desiliconization and desulphuration), is heated, finished or alloyed and deoxidated. The quantity of slag-free liquid pig-iron that has been pre-treated in the blast furnace (1) and a DDD device (2) is separated and introduced into two classic “twin” AOD-L converters (3, 4), where the required chemical process steps (of the heating, decarburization and alloying stages) take place in parallel contrary processes using autogenous chemical energy, the heating stage being carried out first in the first twin AOD-L converter (3) and the decarburization being carried out first in the second twin AOD-L converter (4).

Abstract: A method of producing steel (1) with a high manganese and low carbon content on the basis of liquid pig iron (2) or liquid steel (3) and slag-forming constituents (4) with the object of preventing existing drawbacks of process route in vessels other than, e.g., electrical arc furnaces (18). With steel produced with a high manganese and low carbon content, in a process, the carbon component is reduced to about 0.7-0.8% by a combined blowing of oxygen (7) through top lances (8) and underbath nozzles (9) after feeding of liquid ferro-manganese (50 and liquid steel (3a) in a FeMn-refining converter (6a), wherein a component of a cold end product from premelt is added as cooling means (10), and wherein the carbon component is reduced to about 0.05-0.1% C by a continuous blowing of oxygen (7) through the underbath nozzles.

Abstract: A vertical shaft melting furnace is operated in a method that includes firing a plurality of burners to generate combustion products, and directing jets of the combustion products into the shaft in a bottom region of the shaft. The method further includes directing a jet of hot gas into the shaft in an upper region of the shaft in a non-radial direction, whereby the jet of hot gas can induce a swirl to disperse a concentrated channel of combustion products rising from the bottom region to the upper region through a void in unmelted portions of a load of metal pieces in the shaft. The jet of hot gas directed into the upper region of the shaft can include recirculated flue gas, a mixture of air and recirculated flue gas, or combustion products that are generated by a burner. If the jet of hot gas includes combustion products that are generated by a burner, the burner is a secondary burner that preferably is fired into the shaft with a relatively low heat input.

Abstract: A direct smelting process and a fixed, ie non-rotatable, metallurgical vessel for producing metal from a metalliferous feed material is disclosed. The process is a molten bath-based process which includes injecting solid feed materials with a carrier gas into the molten bath via one or more downwardly extending lance/tuyere (11) and causing gas flow from the molten bath at a flow rate of at least 0.30 Nm3/s/m2 at the interface between the metal layer (15) and the slag layer (16) of the molten bath (under quiescent conditions).

Abstract: A process for producing stainless steels, particularly special steels containing chromium and chromium-nickel, in a smelting arrangement having at least two vessels, for supplying a steel foundry. A charge having mostly iron-containing raw scrap materials and partially carbon-containing alloy carriers is melted in a first vessel. At a temperature of 1460° C., the melt is decarburized by the injection of oxygen so as to reduce the carbon content to less than 0.3%. The melt is heated to a tapping temperature of between 1620° C. to 1720° C. and the carbon content is subsequently reduced to 0.1%. A second charge is melted in a second vessel simultaneously with the decarburizing of the first charge in the first vessel.

Abstract: A method of decarburizing refining molten steel containing Cr in such a manner that oxygen gas, inert gas or a mixture of inert gas and oxygen gas is blown to the surface of bath of molten steel containing Cr in a refining chamber and to a position below the surface of the steel bath. Inert gas is blown to the surface of the steel bath, and oxygen gas, the inert gas or a mixture of oxygen gas and inert gas is blown below the surface of the steel bath in a portion of or all of an overall period in which the concentration of C in the molten steel is in a range of 1 wt % and 0.05 wt %. Slag and molten steel are stirred so as to cause Cr.sub.2 O.sub.3 in the slag and C in the molten steel to positively take part in a reaction represented by expression (1) below:Cr.sub.2 O.sub.3 +3C.fwdarw.

Abstract: The present invention provides a method for refining a molten chromium-containing steel by decarburization according to a combined-blown process, which contributes to an improvement in decarburization rate and realizes efficient decarburization while preventing [Cr] contained in the molten steel from being oxidized. The method is characterized in that, in a region where the [C] concentration of the molten chromium-containing steel is not less than 0.15%, oxygen or a gas mixture of oxygen with an inert gas is blown through a top-blown lance onto the surface of the molten steel under the following conditions:(1) the velocity of the gas immediately after spouting through one or at least two nozzle holes of the top-blown lance is not less than the velocity of sound; and(2) the ratio of the length h of a zone, in the vicinity of the surface of the molten steel, where the gas jet velocity is less than the velocity of sound, to the minimum hole diameter d.sub.0 of said nozzle, h/d.sub.

Abstract: Process and apparatus for post combustion of reaction gases generated in a molten iron bath above the bath by means of at least one jet of oxidizing gases, whereby energy thereby produced is transferred to the bath and whereby the or each jet of oxidizing gases is injected with a swirl through one or more tuyeres towards the surface of the bath or the or each jet of oxidizing gases is injected in the form of a hollow jet through one or more tuyeres towards the surface of the bath.