Provided are an ultra-clean rare earth steel and an occluded foreign substance modification control method, the steel includes 10-200 ppm of rare earth elements, 50% or more occluded foreign substances in the steel are dispersed into RE-oxygen-sulfide with the average equivalent diameter D.sub.mean ranging from 1-5 μm in a spherical shape or a substantially spherical shape or a granular shape; according to the method, at least 80%, preferably at least 90%, of Al2O3 occluded foreign substances in the steel are modified into RE-oxygen-sulfide, compared with steel with the same components without rare earth, the total amount of the occluded foreign substances in the steel is reduced by 18% or higher, the cracking probability caused by occluded foreign substances such as Al2O3 in traditional pure steel is reduced, the mechanical performance such as the fatigue life of the steel is remarkably improved.

A wire for out-of-furnace treatment of metallurgical melts comprises a metallic sheath which encloses a core comprising at least one element selected from the group consisting of Ca, Ba, Sr, Mg, Si and Al, wherein at least one layer of a composite coating is applied to an inner and/or outer surface of said sheath, which coating consists of a lacquer paint material and contains high-melting ultrafine particles selected from compounds of metal carbides and/or nitrides and/or carbonitrides and/or silicides and/or borides. The composite coating comprises a protector material, for which ferroalloys and/or flux agents are used. The metals contained in the high-melting compounds are titanium and/or tungsten and/or silicon and/or magnesium and/or niobium and/or vanadium. Said coating is applied evenly onto the surface of the sheath.

A method for upgrading used or rejected electric battery cells, which include upgradable compounds, such as iron, zinc, manganese, copper, and fixed and volatile carbon, and heavy metals and dangerous compounds. The used or rejected battery cells are introduced as a load into a furnace for melting metal, such as a cupola furnace, a free arc furnace, or an induction furnace. A device for purifying gases produced by the furnace and for capturing and removing noxious elements, such as mercury, chlorides, and fluorides, and heavy molecules such as dioxins, furans, and aromatic substances, is provided in a discharge route of the hot gases, downstream from the melting furnace.

A method and system for predicting an addition amount of slagging lime during ladle furnace (LF) refining, and an LF refining method are provided. The method includes: S1: calculating an actual sulfur distribution ratio in combination with a Kungliga Tekniska Högskolan (KTH) model and a least square method by using LF refining parameters; S2: calculating, according to a principle of sulfur mass conservation, a mass of final slag by using the LF refining parameters and the actual sulfur distribution ratio obtained in S1; and S3: calculating, according to a principle of material conservation during LF refining, an addition amount of slagging lime during the LF refining by using the LF refining parameters and the mass of the final slag obtained in S2, thereby predicting the addition amount of the required slagging lime.

A method and system for predicting an addition amount of slagging lime during ladle furnace (LF) refining, and an LF refining method are provided. The method includes: S1: calculating an actual sulfur distribution ratio in combination with a Kungliga Tekniska Högskolan (KTH) model and a least square method by using LF refining parameters; S2: calculating, according to a principle of sulfur mass conservation, a mass of final slag by using the LF refining parameters and the actual sulfur distribution ratio obtained in S1; and S3: calculating, according to a principle of material conservation during LF refining, an addition amount of slagging lime during the LF refining by using the LF refining parameters and the mass of the final slag obtained in S2, thereby predicting the addition amount of the required slagging lime.

Ti, N, Al, Mg, and Ca concentrations are controlled in order to prevent aggregation of TiN inclusions. Furthermore, not only is a Fe—Cr—Ni alloy having superior surface property provided, but also a method is proposed in which the Fe—Cr—Ni alloy is produced at low cost using commonly used equipment. The Fe—Cr—Ni alloy includes C≤0.05%, Si: 0.1 to 0.8%, Mn: 0.2 to 0.8%, P≤0.03%, S≤0.001%, Ni:16 to 35%, Cr: 18 to 25%, Al: 0.2 to 0.4%, Ti: 0.25 to 0.4%, N≤0.016%, Mg: 0.0015 to 0.008%, Ca≤0.005%, O: 0.0002 to 0.005%, freely selected Mo: 0.5 to 2.5% in mass % and Fe and inevitable impurities as the remainder, wherein Ti and N satisfy % N×% Ti≤0.0045 and the number of TiN inclusions not smaller than 5 μm is 20 to 200 pieces/cm.sup.2 at a freely selected cross section.

A sulfur additive is added to molten steel. At that time, the yield of sulfur in the molten steel is stabilized and nozzle blockage at the time of continuous casting due to impurities is prevented. A sulfur additive used for molten steel which contains iron sulfide ore particles with a particle size of 5.0 to 37.5 mm in 85 mass % or more with respect to the total mass % of the sulfur additive is used to produce Al deoxidized resulfurized steel containing S: 0.012 to 0.100 mass %.

A sulfur additive is added to molten steel. At that time, the yield of sulfur in the molten steel is stabilized and nozzle blockage at the time of continuous casting due to impurities is prevented. A sulfur additive used for molten steel which contains iron sulfide ore particles with a particle size of 5.0 to 37.5 mm in 85 mass % or more with respect to the total mass % of the sulfur additive is used to produce Al deoxidized resulfurized steel containing S: 0.012 to 0.100 mass %.

A method for desulfurizing molten steel comprising taking a sample out from molten steel after tapping from a converter or during secondary refining and analyzing the sample rapidly with high accuracy by a method comprising a high frequency induction heating step wherein the sample is combusted and oxidized under the high frequency induction heating in an oxygen atmosphere having an oxygen purity of 99.5 vol % or more to convert S in the sample into SO.sub.2 and an analyzing step wherein SO.sub.2-containing gas produced in the high frequency induction heating step is analyzed through an ultraviolet fluorescence method to quantify S concentration of the sample.

Embodiments include a method of making steel with low carbon content which includes preparing a heat of molten steel composition in a steelmaking furnace to a tapping temperature ranging from 2912 to 3060 degrees F. and tapping into a ladle the molten steel composition having an oxygen level is about 700 to 1000 ppm. The molten steel composition is then transported to a ladle metallurgy furnace, where the molten steel composition is further heated and one or more elements are added to the molten steel composition. The molten steel composition is then transported from the ladle metallurgy furnace to a vacuum tank degasser. The molten steel composition is then decarburized and one or more elements are added to the molten steel composition at the vacuum tank degasser for deoxidization and desulphurization. The molten steel composition is then transported to a ladle metallurgy furnace to further adjust chemistry and temperature.