Patent application number | Description | Published |
20090038439 | PROCESS FOR PRODUCING STEEL FOR HIGH-CARBON STEEL WIRE MATERIAL WITH EXCELLENT DRAWABILITY AND FATIQUE CHARACTERISTICS - The present invention provides a method suitable for manufacturing a steel material for obtaining a steel wire rod with decreased amount of hard nonmetallic inclusions and improved drawability and fatigue property by adequately controlling the conditions of secondary refining and manufacturing conditions in a converter. Converter blowing is performed by taking molten iron, cold iron, and steel scrap as main raw materials to be charged into a converter, the ratio of these components based on all the main raw materials being such that the molten iron takes 96 to 100% (means wt. %, same hereinbelow), the cold iron takes 4% or less, and the steel scrap takes 2% or less, and by setting an average P concentration in all the main raw materials to 0.02% or less, and operations are carried out such that a flow rate of gas for stirring molten steel during secondary refining after completion of the converter blowing is set to 0.0005 Nm | 02-12-2009 |
20100180723 | METHOD FOR MANUFACTURING MOLTEN IRON - A method for manufacturing molten iron includes a step of charging a carbonaceous material, a flux, and solid reduced iron obtained by thermally reducing carbon composite iron oxide agglomerates into an arc melting furnace and melting the solid reduced iron using arc heating in the melting furnace while an inert gas is blown into a molten iron layer contained in the melting furnace from a bottom blowing tuyere disposed on a bottom of the melting furnace to stir the molten iron layer, wherein the carbonaceous material is charged so that a carbonaceous material suspending slag layer in which the carbonaceous material is suspended is formed in an upper portion of a slag layer formed on the molten iron layer by slag produced when the solid reduced iron is melted into the molten iron and so that a carbonaceous material coating layer composed of only the carbonaceous material is further formed on the carbonaceous material suspending slag layer, and the molten iron and the slag stored in the melting furnace are tapped from a tap hole formed in a lower portion of a furnace wall of the melting furnace. | 07-22-2010 |
20100229685 | PROCESS FOR PRODUCING MOLTEN IRON - A process for producing molten iron is a process in which while an inert gas is blown into a molten iron layer in an iron bath type melting furnace through bottom-blown tuyeres provided in a hearth bottom thereof to stir the molten iron layer, a carbon material, an additive flux, and solid reduced iron obtained by heating reduction of carbon composite iron oxide briquettes are charged into the above melting furnace, and top blowing of an oxygen-containing gas is performed through a top-blown lance provided for the melting furnace, so that the solid reduced iron is melted by combustion heat obtained by combusting the carbon material and/or carbon in molten iron to form molten iron. In addition, in this process for producing molten iron, the carbon material is charged so as to form a carbon material suspension slag layer in which the carbon material is suspended at an upper layer portion of a slag layer which is formed of slag generated when the solid reduced iron on the molten iron layer is melted into molten iron and further so as to form a carbon material covering layer made of only the carbon material on the carbon material suspension slag layer, and the molten iron and the slag accumulated in the melting furnace are discharged through a taphole provided at a lower portion of a furnace side of the melting furnace. | 09-16-2010 |
20110094703 | METHOD OF CONTINUOUS CASTING OF HIGH-ALUMINUM STEEL AND MOLD POWDER - The invention provides a method of continuous casting for producing a slab excellent in surface quality by preventing formation of depressions and occurrence of cracking of a slab even in the case of producing a high Al steel having an Al content of 0.1% or more by continuous casting. At the time of continuous casting of a high-Al molten steel containing prescribed chemical components by using a mold powder, a powder containing T—CaO: 35 to 55%, SiO | 04-28-2011 |