Provided is an alloy steel manufacturing method, the method including: preparing a manganese-containing first molten ferroalloy; preparing a chromium-containing second molten alloy; preparing molten steel; mixing the first molten ferroalloy and the second molten ferroalloy to manufacture third molten ferroalloy; and mix pouring the third molten ferroalloy and the molten steel to manufacture an alloy steel, wherein the phosphorous concentration in the molten steel may efficiently be controlled by reducing the converter end point temperature of the molten steel to improve a phosphorous control capacity during converter refining.

When performing dephosphorization treatment of hot metal by adding a refining agent as a lime source and an oxygen source (dephosphorizing agent(s) and a gaseous oxygen source into the hot metal accommodated in a hot metal holding container, the refining agent used is a refining agent having an Ig-loss value of from 4.0% by mass to 35.0% by mass and including 60% by mass or more of quicklime.

A method removes phosphorus from a phosphorus-containing substance. In the method, the phosphorus-containing substance that is used as a raw material for metal smelting or refining is reacted with a nitrogen-containing gas so that phosphorus in the phosphorus-containing substance is removed through nitriding. Prior to a treatment of a nitriding removal of phosphorus from the phosphorus-containing substance, a treatment is performed in which the phosphorus-containing substance is heated to an unmolten state temperature range so as to react with a reducing agent, thereby reducing at least a part of metal oxide in the phosphorus-containing substance.

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.

The present disclosure is related to compacted calcium-based granules, in particular pellets, spheroidal/lens-shaped pellets, exhibiting specific chemical and physical properties and comprising a source of calcium and/or a source of magnesium, and optionally one or more additives. The present disclosure further relates to a method for the production of said pellets and to the use of said pellets in, for example, the steel industry, agriculture (in particular precision farming) and the glass industry.

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 method of making steel by deeply dephosphorization in a hot metal tank and decarburization using semi-steel with nearly zero phosphorus load in a converter includes the following steps: putting an efficient dephosphorization agent into the hot metal tank in advance, and conducting dephosphorization during blast furnace tapping and transportation of blast furnace hot metal by the hot metal tank to obtain semi-steel with [P] less than 0.04 wt. % and [C] greater than or equal to 3.5 wt. %; and removing dephosphorization slag, and pouring the semi-steel into the converter for decarburization to obtain molten steel. The efficient dephosphorization agent includes iron oxide scale, lime, and composite calcium ferrite. According to the method, a phosphorus content of the blast furnace hot metal is reduced to be less than or equal to 0.04 wt. % through the efficient dephosphorization agent.

Proposed is a method for removing phosphorus from a phosphorus-containing substance which is applicable in an industrial scale so as to effectively reduce phosphorus contained in the phosphorus-containing substance. In this method, the phosphorus-containing substance used as a raw material for metal smelting or metal refining is reacted with a nitrogen-containing gas at a treatment temperature T (° C.) which is lower than a melting temperature (T.sub.m) of the substance, so that phosphorus is removed preferably in the form of phosphorus nitride (PN). In this regard, a nitrogen partial pressure and an oxygen partial pressure in the nitrogen-containing gas are preferably controlled, thereby reducing a load of dephosphorization process, for example.

Process for dephosphorization of molten metal during a refining process using a lime composition in the form of compacted particles having a Shatter Test Index of less than 20%, leading to a refined metal reduced in phosphorus components to the extent that the refined metal reduced in phosphorus is showing a phosphorus content lower than 0.02 w % based on the total weight of the refined metal reduced in phosphorus.

A method of making steel by deeply dephosphorization in a hot metal tank and decarburization using semi-steel with nearly zero phosphorus load in a converter includes the following steps: putting an efficient dephosphorization agent into the hot metal tank in advance, and conducting dephosphorization during blast furnace tapping and transportation of blast furnace hot metal by the hot metal tank to obtain semi-steel with [P] less than 0.04 wt. % and [C] greater than or equal to 3.5 wt. %; and removing dephosphorization slag, and pouring the semi-steel into the converter for decarburization to obtain molten steel. The efficient dephosphorization agent includes iron oxide scale, lime, and composite calcium ferrite. According to the method, a phosphorus content of the blast furnace hot metal is reduced to be less than or equal to 0.04 wt. % through the efficient dephosphorization agent.