When storing a molten ferroalloy or molten nonferrous metal, the molten ferroalloy or molten nonferrous metal is denitrified or prevented from absorbing nitrogen, and thus post processing such as a denitrification process may not be performed. For this, there is provided a method of producing molten manganese-containing steel, the method including: preparing a molten ferroalloy or a molten nonferrous metal; maintaining the molten ferroalloy or the molten nonferrous metal at a temperature equal to or higher than a melting point thereof; and pouring the molten ferroalloy or the molten nonferrous metal into prepared molten steel, wherein in the maintaining of the molten ferroalloy or the molten nonferrous metal, the molten ferroalloy or the molten nonferrous metal is subjected to a nitrogen-absorption prevention process or a denitrification process.

A method of reducing metal oxides in a plasma arc torch comprising a cathode and an anode. The method comprises collecting a set of metallic oxide ore and filtering the set of ore based on a particle size. The method further comprises preprocessing the filtered ore with the application of a heat gradient or an electric current. The preprocessed ore is mixed with a composition of reduction gases. The mixture is injected into the plasma arc torch to form a post-plasma mixture. The method further comprises collecting the post-plasma mixture and analyzing the post-plasma mixture. The method also comprises separating the post-plasma mixture into a set of slag and a set of liquid.

Described are steel production systems and methods, and a furnace and methods of using such furnace to produce steel. In some embodiments, the furnace may include a shell having a top portion and a bottom portion. There may be a roof connected to the top portion that can have feed ports for the introduction of a metal oxide into the furnace. The shell may include injectors that can inject a fluid into the furnace. The bottom portion may be connected to a hearth. The furnace can melt the metal oxide to form a molten bath in the hearth. The molten bath may have a slag layer and a metal layer. The fluid can reduce the metal oxide in the slag layer to form molten metal.

An electric furnace with energy utilization efficiency at a low cost. In an electric furnace, a preheating chamber 2 with a melting chamber 1 is used to preheat iron scrap x, an exhaust gas generated in melting chamber 1 is passed through preheating chamber 2 filled with the iron scrap x to preheat the iron scrap x, the iron scrap x descends in the preheating chamber 2 to be supplied into melting chamber 1, and the iron scrap x is melted to obtain molten iron m. The iron scrap x is charged into preheating chamber 2 so that bulk density is not less than 0.50 t/m.sup.3 and less than 1.00 t/m.sup.3 and an iron scrap filling ratio H.sub.SC/H.sub.SF in the preheating chamber 2 is 0.5 to 0.8. A carbonaceous material is used for melting the iron scrap x, and oxygen and the carbonaceous material are blown into the melting chamber.

A process for steel production that includes: production of sponge iron from iron oxide-containing starting material by direct reduction with reduction gas, wherein the reduction gas has at least 20% by volume of hydrogen H.sub.2, and production of an iron melt having a carbon content of 1-5% by mass from the sponge iron.

Sponge iron is subjected to a treatment that includes: energy input and addition of additives to produce a melt and a slag, wherein the energy input is effected substantially from electricity and wherein the slag has a basicity B2 of less than 1.3, preferably less than 1.25, particularly preferably less than 1.2, adjustment of the carbon content in the melt, reduction of at least a sub-amount of the iron oxides present in the sponge iron

The slag is separated during and/or after the treatment.

A molten steel refining method. The method includes refining molten steel contained in a ladle by using an RH vacuum degasser. In the refining step, the surface of the molten steel circulating in a vacuum vessel of the RH vacuum degasser is subjected to a plasma treatment in which the surface of the molten steel is exposed to a hydrogen gas or an inert gas containing a hydrogen gas in the form of plasma gas under the conditions that satisfy a specified formula to reduce the amount of at least one element selected from oxygen, nitrogen, and sulfur, contained in the molten steel.

Methods for producing steel using super-pure iron ore powder and hydrogen are provided. In the method, iron ore concentrate is purified to form super-pure iron ore powder. The super-pure iron ore powder is reduced with hydrogen introduced into a first furnace, which can be a hydrogen electric furnace, a hydrogen tube furnace, a hydrogen box furnace, an electromagnetic induction furnace, or a hydrogen thermal plasma furnace. The reduced iron product can be melted in the same or a different furnace, which can be a hydrogen electric furnace, belt furnace, an electromagnetic induction furnace, hydrogen thermal plasma furnace, or an electrical arc furnace. The reducing and melting steps result in a steel product. The present methods result in zero carbon dioxide emissions.

Molten iron is produced in an electric furnace with high energy utilization efficiency at a low cost. In an electric furnace in which a shaft-type preheating chamber is provided on and continuously with a melting chamber and used to preheat iron scrap, an exhaust gas generated in the melting chamber is passed through the preheating chamber filled with the iron scrap so as to preheat the iron scrap, the iron scrap thus preheated is sequentially caused to descend in the preheating chamber so as to be supplied into the melting chamber, and the iron scrap is melted in the melting chamber to obtain molten iron m.

Described are steel production systems and methods, and a furnace and methods of using such furnace to produce steel. In some embodiments, the furnace may include a shell having a top portion and a bottom portion. There may be a roof connected to the top portion that can have feed ports for the introduction of a metal oxide into the furnace. The shell may include injectors that can inject a fluid into the furnace. The bottom portion may be connected to a hearth. The furnace can melt the metal oxide to form a molten bath in the hearth. The molten bath may have a slag layer and a metal layer. The fluid can reduce the metal oxide in the slag layer to form molten metal.

A method of injecting selected material along a preselected path into charged material. The charged material at least partially obstructs the preselected path. An injection device includes a central barrel through which a carrier stream of a transport gas is directed, and the selected material is introduced into the carrier stream to form a transport stream that exits the central barrel at an output end. The injection device also includes an outer barrel coaxial with the central barrel to define an annular space. An annular shroud stream of a shroud gas exits the annular space at a downstream end. The annular shroud is directed along the preselected path to provide an opening in the scrap steel pieces. Subsequently, the transport stream and the annular shroud stream are directed along the predetermined path to inject the selected material through the opening into the charged material.