A method for dephosphorization of molten iron includes, while blowing a hydrogen gas, a hydrocarbon gas, or a mixture of these gases into molten iron held in a vessel, supplying a slag-forming agent and an oxygen source to perform a dephosphorization treatment of the molten iron and obtain dephosphorized molten iron, and after the dephosphorization treatment, separating slag floating on a surface of the dephosphorized molten iron from the dephosphorized molten iron. In this method for dephosphorization of molten iron, before the dephosphorization treatment, when obtaining molten iron by melting a cold iron source in a melting furnace and discharging the molten iron from the melting furnace into the vessel, one or both of the following are performed: separating generated slag from the molten iron before the discharge; and separating slag that has flowed into the vessel along with the molten iron from the molten iron.

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.

Provided are a molten metal refining device and method. The molten metal refining method includes: preparing molten metal; dipping an impeller into the molten metal; supplying a liquid dephosphorization agent on top of the molten metal; and stirring the molten metal by rotating the impeller, wherein a solid dephosphorization agent in a powder state is supplied through the lower portion of the impeller in the stirring of the molten metal, thereby improving the stirring efficiency of the molten metal and efficiently controlling the phosphorus concentration in the molten 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.

An improved method of manufacturing a powder metal material by water, gas, plasma, or rotating disk atomization is provided. The method includes adding at least one additive to a melted metal material before or during the atomization process. The at least one additive forms a protective gas atmosphere surrounding the melted metal material which is at least three times greater than the volume of melt to be treated. The protective atmosphere prevents introduction or re-introduction of contaminants, such as sulfur (S) and oxygen (O.sub.2), into the material. The atomized particles produced include at least one of the following advantages: median circularity of at least 0.60, median roundness of at least 0.60, less internal pores, less internal oxides, and an increased sphericity of the microstructural phases and/or constituents.

There is proposed a method for preliminary treatment of molten iron wherein heat source for dissolving scrap is ensured sufficiently to improve iron yield while decreasing phosphorus concentration efficiently by suppressing the amount of flux solvent used in the process of desiliconization, dephosphorization and decarburization. In the method for preliminary treatment of molten iron by conducting desiliconization and dephosphorization of molten iron with a converter type container, molten iron is first charged into the converter type container to conduct desiliconization and then intermediate slag removal is conducted, and subsequently a lime-based flux solvent is added to the container while blowing oxygen to conduct dephosphorization of the molten iron, and thereafter newly untreated molten iron is charged into the container to conduct desiliconization, and subsequently the above treatments are repeatedly conducted with the same container.

A method for preparing low-cost clean steel includes steps of: preliminarily desulfurizing iron melt: preliminarily desulfurizing in an iron melt channel during blast furnace tapping and during iron folding in an iron folding room, adding a desulfurizing ball into the iron melt during the blast furnace tapping or the iron folding; dephosphorizing and controlling sulfur: dephosphorizing and controlling sulfur during converter steelmaking, in such a manner that P0.014% and S0.004% during tapping; rapidly dephosphorizing by slag-forming: rapidly dephosphorizing by slag-forming during converter tapping, at a converter end point, controlling a C content at 0.020.10%, adding a dephosphorizing ball through an alloy chute during the converter tapping, blowing argon and stirring at the same time; purifying steel melt during RH refining: adding a purifying ball at a late stage of the RH refining when a vacuum degree is at 66.7500 Pa; and continuously casting with whole-process protection.

An impeller for stirring a melt pool includes: an impeller body extending in the length direction; a blowing nozzle which is provided in such a way as to pass through one part at the bottom end of the impeller body; and a blade provided on the upper part of the impeller body. As a result, when the impeller is used, a stirring flow produced due to the blade and a stirring flow due to substances blown into the melt-pool via the blowing nozzle correspond to each other, and the two flows are combined such that the overall stirring force is improved. Consequently, it is possible to improve the efficiency of stirring by the impeller as compared with hitherto, and, as a result, refining efficiency in the refining step is improved as the rate of reaction between the melt-pool and additives is increased.

The invention relates to a modification body for the production of spheroidal graphite cast iron and to the method for producing a cast part using the modification body according to the invention, and to the cast part itself. The modification body serves for the production of spheroidal graphite cast iron, in particular with a predominantly ferritic structure, containing a carrier material, preferably an iron-silicon alloy, wherein the modification body contains 7-16 weight percent of boron.

Provided are a hot-rolled, low-temperature-resistant, H-shaped steel with a grade of 420 MPa and a preparation method therefor. The H-shaped steel comprises the following chemical components in percentages by weight: C: 0.08-0.10%, Si0.2%, Mn: 1.25-1.45%, V: 0.03-0.045%, Ti: 0.015-0.025%, Cr: 0.15-0.30%, Als: 0.02-0.04%, N: 0.007-0.01%, P0.008%, S0.005%, O0.004%, and the balance being Fe and inevitable impurities. In the preparation method, the characteristic of the flange of the small-specification H-shaped steel being thin in rectangular blank rolling is combined, the design of a low content of C suitable for normalizing rolling being in cooperation with a V micro-alloyed component is used, an appropriate amount of Cr is added to control the cooling rate, and the situation whereby the low-temperature impact toughness of steel deteriorates due to the occurrence of abnormal structures such as widmanstatten is avoided, thus a stably controlled, high-strength and high-toughness, hot-rolled, H-shaped steel with a grade of 420 MPa or more is obtained on a hot-rolled H-shaped steel rolling mill.