A method for recycling processing of dust generated in a converter furnace, includes: crushing and drying a cake formed by adding a binder to a slurry containing iron powder-containing dust that is generated at the time of converter blowing and wet-collected to produce a mixed slurry and subjecting the produced mixed slurry to a dehydration treatment in a filter press; accumulating the cake in an accumulation tank; and charging the cake into a converter furnace 10, the crushed product in the accumulation tank 25 is kept at a temperature of less than 90 C. by forcibly passing air into the accumulation tank 25 and charged into a converter furnace according to the converter operation.

A non-oriented electrical steel sheet with fine magnetic performance, and a calcium treatment method therefor, including an RH (Ruhrstahl-Heraeus) refinement step. The RH refinement step sequentially comprises a decarbonization step, an aluminum deoxidation step, and a step of adding calcium alloy. In the step of adding calcium alloy, time when the calcium alloy is added satisfies the following condition: time interval between Al and Ca/total time after Al=0.2-0.8. In this method, production cost is reduced, the production process is simple, a normal processing cycle of RH refinement is not affected, the device is convenient in operation and is controllable, and foreign substances are controllable in both shape and quantities. The non-oriented electrical steel sheet prepared according to the present invention has fine magnetic performance, and the method can be used for mass production of the non-oriented electrical steel sheet with fine magnetic performance.

A non-oriented electrical steel sheet with fine magnetic performance, and a calcium treatment method therefor, including an RH (Ruhrstahl-Heraeus) refinement step. The RH refinement step sequentially comprises a decarbonization step, an aluminum deoxidation step, and a step of adding calcium alloy. In the step of adding calcium alloy, time when the calcium alloy is added satisfies the following condition: time interval between Al and Ca/total time after Al=0.2-0.8. In this method, production cost is reduced, the production process is simple, a normal processing cycle of RH refinement is not affected, the device is convenient in operation and is controllable, and foreign substances are controllable in both shape and quantities. The non-oriented electrical steel sheet prepared according to the present invention has fine magnetic performance, and the method can be used for mass production of the non-oriented electrical steel sheet with fine magnetic performance.

A thin steel sheet contains, in terms of percentage by mass, from 0.010 to 0.200% of C, more than 2.00% and 4.00% or less of Si, from 0.01 to 3.00% of Mn, 3.00% or more and less than 10.00% of Ni, from 11.00 to 20.00% of Cr, from 0.010 to 0.200% of N, from 0 to 3.00% of Mo, from 0 to 1.00% of Cu, from 0 to 0.008% of Ti, from 0 to 0.008% of Al, and the balance of Fe, with unavoidable impurities; and having a number density of a non-metallic inclusion lining up with an interparticle distance in the rolling direction of 20 mm or less and an interparticle distance in the sheet thickness direction of 10 mm or less that has a length in the rolling direction of 40 mm or more of 3.0 or less per square millimeter on the L cross section.

A thin steel sheet contains, in terms of percentage by mass, from 0.010 to 0.200% of C, more than 2.00% and 4.00% or less of Si, from 0.01 to 3.00% of Mn, 3.00% or more and less than 10.00% of Ni, from 11.00 to 20.00% of Cr, from 0.010 to 0.200% of N, from 0 to 3.00% of Mo, from 0 to 1.00% of Cu, from 0 to 0.008% of Ti, from 0 to 0.008% of Al, and the balance of Fe, with unavoidable impurities; and having a number density of a non-metallic inclusion lining up with an interparticle distance in the rolling direction of 20 mm or less and an interparticle distance in the sheet thickness direction of 10 mm or less that has a length in the rolling direction of 40 mm or more of 3.0 or less per square millimeter on the L cross section.

The invention relates to interstitial free (IF) steel production using scrap and its production method.

In particular, the invention relates to IF steel with improved formability and strength properties and its production method, which is produced using scrap to eliminate the dependence on raw iron ore in IF steel production by using recyclable and reusable resources.

The present invention relates to IF steel and its production method, which is produced using 50-100% scrap, which eliminates dependence on raw iron ore in IF steel production by utilizing recyclable, reusable resources.

The invention relates to interstitial free (IF) steel production using scrap and its production method.

In particular, the invention relates to IF steel with improved formability and strength properties and its production method, which is produced using scrap to eliminate the dependence on raw iron ore in IF steel production by using recyclable and reusable resources.

The present invention relates to IF steel and its production method, which is produced using 50-100% scrap, which eliminates dependence on raw iron ore in IF steel production by utilizing recyclable, reusable resources.

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.

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.

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.