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.

A bearing steel includes, as a metallographic structure, inclusions which contain complex oxysulfides including Rare Earth Metal, Ca, O, S, and Al, TiN, MnS, Al.sub.2O.sub.3, and complex oxides including Al and Ca, wherein, a number fraction of the complex oxysulfides in a total number of the inclusions is 50% to less than 100% and a number of complex oxysulfides having a major axis of 5 μm or more is 0.001 pieces to 2 pieces in an observed section of 1 mm.sup.2, and a number of TiN existing independently from the complex oxysulfides and having a major axis of 5 μm or more is 0.001 pieces to less than 1.0 piece in an observed section of 1 mm.sup.2.

Disclosed is a method for controlling a Ti concentration in a steel when manufacturing a silicon-deoxidized steel comprising 0.1 to 3% by mass of Si and 0.0001 to 0.005% by mass of Al by ladle refining of a molten steel, the method including the step of: adding an oxide including TiO.sub.2 to a slag in a ladle during the ladle refining, wherein the slag produced at end of the ladle refining satisfies formulas (1) to (7) below:

0.5≦CaO/SiO.sub.2≦1.8  (1)

4% by mass≦Al.sub.2O.sub.3≦20% by mass  (2)

MgO≦15% by mass  (3)

1.5% by mass≦TiO.sub.2≦10% by mass  (4)

CaO+SiO.sub.2+Al.sub.2O.sub.3+MgO+TiO.sub.2≧90% by mass  (5)

0.4≦TiO.sub.2/MnO≦5  (6)

1≦TiO.sub.2/T.Fe≦10  (7)

where a compound represented by a chemical formula represents the content of the compound in percent by mass; and T.Fe represents the total concentration, in mass ratio, of Fe contained in Fe oxides in the slag.

The method employs a desulfurization agent that is introduced into a smelt of one of molten pig iron and molten steel. The desulfurization agent contains calcium oxide, bitumen and at least one flux agent, with the agent containing 1 to 10% by weight bitumen.

Process for manufacturing a slag conditioning agent for steel desulfurization wherein a dried slag material obtained from secondary steelmaking process is mixed with quicklime particles to produce a slag conditioning agent.

Disclosed is a slag discharging method in a process of producing ultra-low phosphorus steel, which relates to the technical field of iron and steel smelting, and in which molten steel is mixed with lime first to produce basic slag; then converting is performed with oxygen to increase the oxidizability of the basic slag; and a carbon-containing reducing agent is finally added, so that in the process that the carbon is oxidized to release a large amount of carbon monoxide gas, phosphates are captured, and the basic slag is rapidly foamed and overflows from the opening of the steel ladle, so that conditions are no longer available for rephosphorization. Also disclosed is a method for producing ultra-low phosphorus steel, which includes the above-described slag discharging method in a process of producing ultra-low phosphorus steel, and refining and ingotting after slag discharge.

Provided is a dephosphorizing flux configured to adjust a phosphorous component contained in molten steel, the dephosphorizing flux includes a main material including BaCO.sub.3 and a supplementary material, wherein the supplementary material includes a first material containing either of NaHCO.sub.3 or Na.sub.2CO.sub.3 and a second material containing CaF.sub.2. Thus, in accordance with a dephosphorizing flux and a method for preparing the same of the present disclosure, the plugging of a lower blowing nozzle that blows a carrier gas during dephosphorization may be prevented while improving a dephosphorization ratio. In addition, since environment polluting substances are not used as in conventional arts, environment pollution risk may be reduced, and the cost burden due to the facility for pollution prevention and harmful substance management may be alleviated.

Provided is steel for a wind power gear with improved purity and reliability. The chemical components thereof comprise, in percentages by mass: 0.15-0.19% of C, ≤0.4% of Si, 0.5-0.7% of Mn, ≤0.012% of P, ≤0.006% of S, 1.5-1.8% of Cr, 0.28-0.35% of Mo, 1.4-1.7% of Ni, and 0.02-0.04% of Al, with the balance being Fe and inevitable impurities. A smelting method therefor comprises adding raw materials to a converter for primary melting, transferring same to a refining furnace for refining, carrying out continuous casting after vacuum degassing, and transferring same to a gas protection furnace for electroslag remelting. According to the present invention, a pure electroslag master batch is obtained by continuous casting, and the purity of the material is further improved by means of an electroslag remelting procedure; and the prepared steel material is used in a wind power gear, such that the flaw detection pass rate is significantly increased, large-particle inclusions in the steel material are significantly reduced, and the inclusions are fine and dispersed.

Provided is a red mud-based composite calcium ferrite and a preparation method and use thereof. The preparation method of the red mud-based composite calcium ferrite includes the following steps: mixing red mud and a calcium source, and roasting an obtained mixture in an oxygen-containing atmosphere to obtain the red mud-based composite calcium ferrite; where the calcium source is selected from the group consisting of lime and calcium carbonate. In the present disclosure, the composite calcium ferrite is prepared using a solid waste red mud, with a greatly reduced cost of raw materials; on the other hand, compared with traditional calcium ferrite, the composite calcium ferrite mainly has phase structures of CaFe.sub.2O.sub.4, Ca.sub.2FeAlO.sub.5, and Ca.sub.2Fe.sub.2O.sub.5. Therefore, the composite calcium ferrite has a lower melting point, a higher lime dissolution efficiency, and better fluxing and dephosphorization effects during primary smelting and refining of molten steel, and has broad prospects for use in industry.

A fluorite synthetic stone comprises: (a) a glass matrix comprising Ca, Si and O, and having a predetermined weight ratio of Ca to Si; and (b) CaF.sub.2 crystals dispersed in the glass matrix at a concentration of at least about 70 wt.%. A method of making fluorite synthetic stones includes formulating a particulate mixture comprising: CaF.sub.2 crystals at a concentration of at least about 70 wt.%; and an excipient having a predetermined weight ratio of Ca to Si. Aggregates are prepared from the particulate mixture. The aggregates are heat treated to form a plurality of fluorite synthetic stones, where each synthetic stone comprises: a glass matrix comprising Ca, Si and O; and CaF.sub.2 crystals dispersed in the glass matrix at a concentration of at least about 70 wt.%.