Abstract: A method that, regarding a process of refining molten iron, can increase the thermal margin and the amount of cold iron source to be used. A burner having jetting holes for jetting a fuel and a combustion supporting gas is provided at a leading end part of one lance that top-blows an oxidizing gas to molten iron contained in a converter-type vessel, or at a leading end part of another separate lance. A powdery auxiliary raw material or an auxiliary raw material processed into a powder form that is blown into the molten iron from the one lance or the other lance passes through a flame formed by the burner. This top-blowing lance for a converter is configured to secure a predetermined heating time and powder-fuel ratio. Also, a method for adding an auxiliary raw material and a method for refining of molten iron that use this top-blowing lance.

Abstract: A molten iron refining method having, an auxiliary material, and an oxidizing gas supplied through a top-blowing lance, to a cold iron source and molten pig iron that are contained/fed in a converter-type vessel, and molten iron is subjected to a refining process. A pre-charged cold iron source is charged into the converter-type vessel at an amount not larger than 0.15 times. A furnace-top-added cold iron source that's part or all of the cold iron source and added from a furnace top is fed during the refining process. A burner at a leading end of the top-blowing lance that spray holes through which a fuel and a combustion-supporting gas are ejected. During the refining process, a powdery auxiliary material processed into powder that's part of the auxiliary material is blown in, to pass through a flame formed by the burner.

Abstract: A converter steelmaking method has molten pig iron subjected to dephosphorization process for dephosphorized molten iron, dephosphorized molten iron is subjected to decarburization process for molten steel. For dephosphorization process, a first cold iron source in amount meeting Formula (1) is charged into first converter-type vessel, then undephosphorized molten pig iron is charged and subjected to dephosphorization process. Dephosphorized molten iron is discharged and held in molten metal receiving vessel. After second cold iron source is charged into first converter-type vessel in which dephosphorization process has been performed, the dephosphorized molten iron held in molten metal receiving vessel is charged and subjected to decarburization process. % Ws0?0.1186T?134 (% Ws0?0) . . . (1), where % Ws0: a ratio (%) of first cold iron source to sum of first cold iron source and charge amount of undephosphorized molten pig iron, and T: a temperature (° C.) of undephosphorized molten pig iron.

Abstract: Proposed is a molten iron refining method capable of securing an in-flame staying time period of a heat transfer medium without being influenced by height adjustments of a blowing-purpose oxygen-blowing lance. As far as to a position lower than an upper end inside a converter-type vessel 1, a blowing-purpose oxygen-blowing lance 3 that supplies oxidizing gas and is capable of ascending and descending and at least one burner lance 4 capable of ascending and descending independently of the blowing-purpose oxygen-blowing lance are inserted. From the blowing-purpose oxygen-blowing lance, either oxidizing gas or oxidizing gas and CaO-containing refining agent are blown onto the molten iron. Also, a flame is formed by causing the burner lance to discharge fuel gas and combustion supporting gas. Powder particles discharged from the burner lance are caused to pass through the flame and to be blown onto the molten iron in a heat-transferred state, so that the molten iron is thermally compensated.

Abstract: A molten iron refining method that prevents a cold iron source from remaining unmelted even under the condition of a high ratio of the cold iron source. An auxiliary material is added, and an oxidizing gas is supplied, to cold iron source and molten pig iron that are contained or fed in converter-type vessel, and molten iron is subjected to refining process. Prior to refining process, a pre-charged cold iron source that is charged all at once into the converter-type vessel before the molten pig iron is charged into the converter-type vessel is charged in an amount not larger than 0.15 times the sum of an amount of the pre-charged cold iron source and a charge amount of the molten pig iron, or is not charged. A furnace-top-added cold iron source that is added from a furnace top of the converter-type vessel is fed into converter-type vessel during refining process.

Abstract: A scrap discrimination system and a scrap discrimination method that can improve scrap discrimination technology are provided. A scrap discrimination system includes a scrap part extraction model (221) that extracts, based on a camera image, a scrap part located in a central portion included in the camera image with reference to a window (107) defined in advance in an image, a scrap discrimination model (222), generated by teacher data including training images, that sorts grades of scrap and a ratio of each grade from a scrap image extracted by the scrap part extraction model (221), and an output interface (24) that outputs information on the grades of scrap and the ratio of each grade as discriminated based on the scrap image using the scrap discrimination model (222).

Abstract: A method for producing chromium-containing molten steel from a raw material including a chromium-containing raw material includes a first step in which a slag basicity before rough decarburization by oxygen blowing is adjusted to be not less than 1.5 and not more than 3.0, a slag basicity after rough decarburization by oxygen blowing is adjusted to be not less than 2.0 and not more than 3.5, and then tapping is performed while slag containing a chromium oxide generated by the oxygen blowing is made to remain in the furnace, and a second step in which the slag containing a chromium oxide made to remain is reduced by using a carbon source or a metal source newly added into the same furnace so that chromium is recovered into molten steel. The slag basicity is determined by dividing a CaO concentration by an SiO2 concentration on a mass basis in the slag.

Abstract: Provided are a scrap determination system and method that can improve scrap determination techniques. A scrap determination system (1) comprises: a first scrap determination model (221) generated using teaching data including first learning images, and determines, based on a camera image, grade of scrap in the image and a ratio of the grade; a second scrap determination model (222) generated using teaching data including second learning images, and determines, based on the image, grade of scrap in the image and a ratio of the grade; a selection model (223) configured to determine which of the first scrap determination model (221) and the second scrap determination model (222) is to be used, based on the image; and an output section (24) configured to output information of each grade of scrap and a ratio of the grade determined based on the image using the model selected by the selection model (223).

Abstract: 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.

Abstract: 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.

Abstract: In producing high-quality steel with use of copper-containing steel scraps as an iron source, the copper-containing steel scraps are melted with addition of carbon to produce hot metal for steelmaking, then, copper contained in the hot metal is removed by sulfur-containing flux, and sulfur contained in the hot metal is removed. With this method, the copper in the steel scraps can be removed efficiently and without the need for large facilities. Preferably, the sulfur-containing flux used is flux having Na2S as the main component. The treatment for removing copper in the hot metal is preferably carried out with use of refining equipment with mechanical stirrer or by the flux injecting method. Besides, it is preferable that a shaft furnace having a coke bed formed inside is used to produce hot metal having a higher concentration of sulfur for the copper removal treatment.