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WO2019172195A1 - Procédé de déphosphoration pour fer en fusion - Google Patents

Procédé de déphosphoration pour fer en fusion Download PDF

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Publication number
WO2019172195A1
WO2019172195A1 PCT/JP2019/008447 JP2019008447W WO2019172195A1 WO 2019172195 A1 WO2019172195 A1 WO 2019172195A1 JP 2019008447 W JP2019008447 W JP 2019008447W WO 2019172195 A1 WO2019172195 A1 WO 2019172195A1
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WO
WIPO (PCT)
Prior art keywords
hot metal
dephosphorization
dephosphorizing agent
dephosphorizing
slag
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/JP2019/008447
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English (en)
Japanese (ja)
Inventor
木下　聡
健太郎 田辺
昌平 柿本
遼 北野
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
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Nippon Steel Corp
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Publication date
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Priority to JP2020505021A priority Critical patent/JP6984731B2/ja
Priority to CN201980011223.9A priority patent/CN111670258B/zh
Priority to KR1020207021337A priority patent/KR102406956B1/ko
Publication of WO2019172195A1 publication Critical patent/WO2019172195A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/02—Dephosphorising or desulfurising
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • C21C5/30—Regulating or controlling the blowing
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
    • C21C7/04—Removing impurities by adding a treating agent
    • C21C7/064—Dephosphorising; Desulfurising
    • C21C7/0645—Agents used for dephosphorising or desulfurising
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D3/00—Charging; Discharging; Manipulation of charge
    • F27D3/18—Charging particulate material using a fluid carrier
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/28—Manufacture of steel in the converter
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention relates to a hot metal dephosphorization method.
  • This application claims priority on March 7, 2018 based on Japanese Patent Application No. 2018-040784 filed in Japan, the contents of which are incorporated herein by reference.
  • P (phosphorus) contained in the hot metal adversely affects various properties of the steel, such as strength, toughness, and elongation. Therefore, it is necessary to remove this as much as possible in the steel refining stage.
  • dephosphorization refining The process of removing P from the hot metal is called dephosphorization refining.
  • a dephosphorizing agent which is a compound mainly composed of CaO (or CaCO 3 ) is used.
  • the dephosphorizing agent contributes to dephosphorization by generating slag having dephosphorization ability in dephosphorization.
  • the greater the amount of dephosphorization agent used the higher the basicity of the slag and the better the dephosphorization ability of the slag.
  • the amount of dephosphorizing agent used is large, the amount of slag also increases. Slag has a high environmental impact and its treatment increases refining costs. Therefore, it is desired to reduce the amount of dephosphorization agent by making the dephosphorization process more efficient.
  • Patent Document 1 discloses a hot metal dephosphorization method capable of reducing the spitting amount and reducing the [P] concentration in the hot metal to 0.020% or less.
  • the hot metal charged with CaO-containing material as the first dephosphorizing agent is gas-stirred, and an oxygen-containing gas is blown up to generate cover slag to form the hot metal.
  • a CaO-containing dephosphorizing agent which is a second dephosphorizing agent, is further sprayed onto the molten iron using an oxygen-containing gas as a carrier gas.
  • Patent Document 1 there is no problem of reducing the amount of slag, and there is no disclosure of the method.
  • Patent Document 2 describes a converter that can stably melt even extremely strict P-standard extremely low phosphorus steel while enjoying the advantages of dephosphorization and decarburization refining in the same converter.
  • a refining method is disclosed. In this converter refining method, after the first dephosphorization refining and the subsequent slag removal, before the decarburization refining, the flux is added to perform the second dephosphorization refining, and then the slag removal is performed. Furthermore, by performing decarburization refining after that, the P concentration in the molten steel after completion of decarburization refining can be sufficiently reduced to an extremely low P steel level.
  • Patent Document 2 does not discuss improving the dephosphorization efficiency in each dephosphorization and does not disclose the method.
  • Patent Document 3 discloses a method of performing hot metal preliminary dephosphorization using a medium solvent that does not contain an F source such as CaF 2 in the dephosphorization process performed as the hot metal preliminary process. This method is a method for producing low phosphorus hot metal, and in the dephosphorization process performed as a hot metal pretreatment, iron oxide in slag is supplied by supplying an oxygen source before adding a solvent as a CaO source to the hot metal. It is said that the concentration is increased, and then a solvent as a CaO source is added.
  • it is essential to make the medium solvent into a lump and add it in small amounts.
  • the present invention has a high dephosphorization rate and has high dephosphorization efficiency of hot metal. It is an object to provide a method.
  • the hot metal dephosphorization method includes a step of measuring an Si content in an initial component of the hot metal, a step of introducing a first dephosphorizing agent into the hot metal, and oxygen in the hot metal. A step of dephosphorizing and blowing the molten iron by blowing, and in the step of dephosphorizing and blowing, a powdery second dephosphorizing agent is added to the molten iron, and the second dephosphorization is performed.
  • the amount of oxygen blown into the hot metal after the time was 3 .Before setting to 0 Nm 3 / t.
  • the ratio of the CaO equivalent of the first dephosphorizing agent to the SiO 2 equivalent of the Si content in the initial component of the hot metal is 0. .60 to 2.00 may be used.
  • the amount of the second dephosphorizing agent used is the slag charge base at the end of the step of dephosphorizing the hot metal. The degree may be controlled to be 1.3 to 4.0.
  • the first dephosphorizing agent and the second dephosphorizing agent is used as quick lime, limestone, calcium.
  • the first dephosphorizing agent may be a bulk dephosphorizing agent.
  • the second dephosphorizing agent is selected from the group consisting of Ar, N 2 , CO 2 , and O 2.
  • the hot metal may be blown into the hot metal using one or more kinds of carrier gas.
  • the Si content in the initial component of the hot metal may be 0.25% by mass or more.
  • the hot metal dephosphorization method which can fully dephosphorize hot metal, without increasing the amount of slag is provided. be able to.
  • FIG. 4 is a CaO—SiO 2 —Fe t O ternary phase diagram. It is the schematic which shows the change of Si content of hot metal in dephosphorization refining, and the injection
  • the present inventors have repeatedly studied to improve the dephosphorization ability of dephosphorization without increasing the amount of slag (that is, to increase the dephosphorization efficiency of dephosphorization). Specifically, the present inventors examined means for improving the hatching rate of the dephosphorizing agent introduced into the hot metal during dephosphorization refining. In this embodiment, hatching of the dephosphorizing agent means that the dephosphorizing agent CaO and / or CaCO 3 is melted to form slag.
  • the hatching rate is the basicity after dephosphorization (the value obtained by measuring the basicity of slag collected after dephosphorization), the basic charge (hot metal and additives) This is a value defined as a value divided by the basicity of slag when it is assumed that all of Si of SiO 2 becomes SiO 2 and all of the added dephosphorization agent CaO (or CaCO 3 ) becomes molten CaO.
  • the “mounting basicity” is a value obtained by measuring a slag component, that is, an actual value.
  • the hatching rate is an index indicating the degree of melting of CaO and / or CaCO 3 in the dephosphorizing agent.
  • the basicity of slag is the ratio of the amount of molten CaO and the amount of molten SiO 2 in the slag, and is calculated by the following formula A.
  • Basicity of slag Amount of molten CaO in slag / Amount of molten SiO 2 in slag: Formula A
  • the dephosphorizing agent is a compound containing CaO (or CaCO 3 or the like) as a main component.
  • CaCO 3 contained in the dephosphorizing agent is decomposed into CaO and CO 2 within a short time by the heat of the hot metal.
  • there are auxiliary materials such as quick lime, limestone, and dolomite lime, converter slag, secondary refining slag, and the like containing CaO and the like, and mixtures thereof.
  • CaO contained in the dephosphorizing agent (including CaO derived from CaCO 3 or the like, the same applies hereinafter) causes the following chemical reaction during dephosphorization blowing (blowing oxygen into the molten iron for dephosphorization).
  • this P 2 O 5 is fixed to (CaO), that is, molten CaO in the slag, and a stabilized compound (3CaO ⁇ P 2 O 5 ) is generated.
  • (CaO) is very important for dephosphorization.
  • the present inventors put the first dephosphorizing agent into the hot metal before the start of dephosphorization blowing, and after a certain period of time after the start of dephosphorization blowing, the second dephosphorizing agent was added. It has been found that the hatching rate of the dephosphorizing agent is remarkably improved when it is put into the hot metal. This phenomenon is presumed to be caused by the following mechanism.
  • FIG. 1 is a CaO—SiO 2 —Fe t O ternary phase diagram.
  • the dephosphorizing agent CaO is initially CaO located in the lower left part of the ternary phase diagram of FIG. Since CaO has a relatively high melting point, it exists in an unmelted state in the slag. However, when dephosphorization blowing is performed in the dephosphorization, Si in the hot metal is oxidized and the SiO 2 concentration in the slag increases. As the SiO 2 concentration increases, the dephosphorizing agent CaO becomes a ternary compound of CaO—SiO 2 —Fe t O. That is, the dephosphorizing agent CaO moves from the lower left part of FIG. 1 to the central part along the arrow. The melting point of the compound located in the center of FIG. 1 is lower than the melting point of CaO. Therefore, as the SiO 2 concentration increases, the dephosphorizing agent CaO is easily melted.
  • the first dephosphorizing agent is hardly melted at the start of dephosphorization blowing, and if the second dephosphorizing agent is added at this stage, it is estimated that the first dephosphorizing agent does not melt sufficiently. . Then, even if the amount of SiO 2 in the slag increases with the progress of dephosphorization blowing, it is considered that the unmelted material of the first dephosphorizing agent remains in the slag and the hatching rate decreases.
  • the second dephosphorizing agent when the second dephosphorizing agent is put on standby until the SiO 2 is sufficiently formed, the second dephosphorizing agent is introduced in a state where the hatching of the first dephosphorizing agent has progressed. And the second dephosphorizing agent is believed to be fully hatched.
  • the hot metal dephosphorization method includes a step of measuring the Si content of hot metal, a step of adding a first dephosphorizing agent to the hot metal, and dephosphorizing the hot metal.
  • the second dephosphorizing agent is added to the molten iron, and the second dephosphorizing agent is started to be added at a Si content of 0.
  • the time is from 10% by mass or less until the amount of oxygen blown into the hot metal reaches 3.0 Nm 3 / t.
  • the Si content of the initial component of the hot metal is measured.
  • the measured value of the Si content of the hot metal initial component is required to determine the timing of the second dephosphorizing agent.
  • the measured value of the Si content of the initial component of the hot metal may be used to determine the input amount of the first dephosphorizing agent.
  • the content of elements other than Si in the hot metal may be measured.
  • the initial component of hot metal means the component of hot metal before dephosphorization blowing.
  • the measurement of the Si content of the hot metal may be performed after the hot metal is charged into the furnace or before that.
  • the Si content in the hot metal initial component is not particularly limited, but is preferably 0.25% by mass or more.
  • the dephosphorizing agent CaO is easily melted. That is, in the hot metal dephosphorization method according to this embodiment, it is preferable to increase the SiO 2 concentration in the slag from the viewpoint of further promoting hatching. Therefore, it is preferable that a certain amount of Si is contained in the hot metal initial component before the start of dephosphorization blowing.
  • the Si content of the hot metal before blowing oxygen is 0.25% by mass or more. It is good also considering Si content in the initial component of hot metal as 0.27 mass% or more, 0.30 mass% or more, or 0.32 mass% or more.
  • the first dephosphorizing agent is added to the hot metal.
  • the form and the input amount of the first dephosphorizing agent are not particularly limited, and can be appropriately set according to the hot metal component, the target value of the steel component, and the like. From the viewpoint of preventing input loss, the first dephosphorizing agent is preferably in the form of a lump.
  • the amount of the first dephosphorizing agent introduced is the ratio of the CaO equivalent of the first dephosphorizing agent to the Si equivalent of the Si content in the initial component of the hot metal (that is, the CaO equivalent of the first dephosphorizing agent / It is preferable that the initial content of the hot metal is controlled so that the Si content (SiO 2 equivalent) of the hot metal is 0.60 to 2.00.
  • the CaO equivalent of the dephosphorizing agent is the CaO content of the dephosphorizing agent when it is assumed that all the Ca in the dephosphorizing agent forms CaO.
  • the SiO 2 equivalent of the Si content in the initial component of the hot metal is the amount of SiO 2 when it is assumed that all of the Si in the hot metal has become SiO 2 .
  • the basicity of the slag is approximately 0.60 ⁇ when the Si in the hot metal is substantially all SiO 2 due to the progress of dephosphorization blowing. 2.00.
  • the dephosphorization can be carried out at a high level. This is considered to be because molten CaO is sufficiently supplied into the slag and the dephosphorization ability of the slag can be improved.
  • the ratio of the CaO equivalent of the first dephosphorizing agent and the SiO 2 equivalent of the Si content in the initial component of the hot metal to 2.00 or less, the hatching rate of CaO is kept high, and the dephosphorization efficiency. Can be kept higher.
  • the ratio of the CaO equivalent of the first dephosphorizing agent to the SiO 2 equivalent of the Si content in the initial component of the hot metal is more preferably 0.80 or more, 0.85 or more, or 0.90 or more.
  • the ratio between the CaO equivalent of the first dephosphorizing agent and the SiO 2 equivalent of the Si content in the initial component of the hot metal is more preferably 1.50 or less, 1.20 or less, 1.15 or less, or 1.10. It is as follows.
  • the slag SiO 2 source when Si is separately added to the hot metal before the start of dephosphorization and when the first dephosphorizing agent contains Si, when the slag SiO 2 source is not limited to hot metal, it is derived from other than hot metal Si to be considered should also be taken into account when determining the input of the first dephosphorizing agent. For example, in order to reduce the amount of dephosphorization agent used, when slag generated by dephosphorization is recycled in another dephosphorization, a SiO 2 source derived from other than hot metal is generated. In this case, Si derived from other than hot metal may be included in the “SiO 2 equivalent of Si content in the initial component of hot metal”.
  • the first dephosphorizing agent and other additives so that the estimated basicity based on the charged amount of slag at the end of the Si oxidation reaction in dephosphorization blowing is 0.60 to 2.00. It is sufficient that the amount of charging is controlled.
  • Dephosphorization is carried out by blowing oxygen into the hot metal.
  • the second dephosphorizing agent is charged into the hot metal.
  • the timing of starting the addition of the second dephosphorizing agent is controlled as described below.
  • FIG. 2 shows the start timing of introducing the second dephosphorizing agent into the hot metal.
  • FIG. 2 is a graph schematically showing how the Si content of hot metal decreases as the oxygen blowing in dephosphorization blowing proceeds, and the vertical axis of the graph represents the Si content (mass%) of hot metal.
  • the horizontal axis indicates the amount of oxygen blown into the hot metal (Nm 3 / t).
  • the hatched area in FIG. 2 is the start timing of introducing the second dephosphorizing agent into the hot metal in the hot metal dephosphorization method according to the present embodiment.
  • the second dephosphorizing agent starts to be introduced into the hot metal after the time when the Si content of the hot metal is sufficiently reduced by dephosphorization blowing, that is, after the time when the Si content of the hot metal is reduced to 0.10% by mass or less. Need to be done.
  • the second dephosphorizing agent is insufficient before the first dephosphorizing agent is sufficiently melted due to insufficient SiO 2 in the slag. Therefore, the melting of the dephosphorizing agent is hindered, the hatching rate is lowered, and the dephosphorization efficiency is impaired.
  • the second dephosphorization agent introduction of the second dephosphorization agent into molten iron, or 2.5Nm 3 /t,2.0Nm 3 / t, the oxygen from the time the Si content of the molten iron drops below 0.10 wt% 1 .5Nm 3 / t Start until insufflation.
  • the Si content of the hot metal was reduced to 0.10% by mass or less, the initial components of the hot metal, the components and input amounts of additives such as the first dephosphorizing agent, and the oxygen to the hot metal were It can be estimated from the amount of air blown.
  • the measurement of the Si content of the initial component of the hot metal may be omitted. it can.
  • the input amount of the second dephosphorizing agent is not particularly limited, and can be appropriately set according to the hot metal component, the target value of the steel component, and the like.
  • the form of the second dephosphorizing agent is powdery. By making the second dephosphorizing agent into powder, the second dephosphorizing agent can be continuously fed into the hot metal via the carrier gas blown from the lance. It is possible to suppress a rapid change in slag basicity by continuously adding the second dephosphorizing agent. By stabilizing the slag basicity, it is possible to prevent the occurrence of a sudden slag forming phenomenon and to stabilize the operation.
  • the hatching rate of the second dephosphorizing agent can be improved and the composition of the slag can be easily controlled.
  • the powdery second dephosphorizing agent is blown into the molten iron using a carrier gas.
  • the input amount of the second dephosphorizing agent is preferably controlled so that the basicity of the slag at the end of the step of dephosphorizing the hot metal is 1.3 to 4.0. More preferably, the input amount of the second dephosphorizing agent is controlled such that the basicity of the slag at the end of the step of dephosphorizing the molten iron is 1.3 to 3.0.
  • the amount of the second dephosphorization agent is controlled so that the basicity of the slag at the end of the dephosphorization process is 1.3 or more, the dephosphorization ability of the slag is further improved, and the molten iron is removed. Phosphorus can be implemented at a high level.
  • the input amount of the second dephosphorizing agent may be controlled so that the basicity of the slag at the end of the dephosphorizing step is 1.5 or more, 2.0 or more, or 2.5 or more.
  • the input amount of the second dephosphorizing agent is controlled so that the slag charge basicity at the end of the dephosphorization process is 4.0 or less, the increase in the slag amount is suppressed and the dephosphorization efficiency is reduced.
  • the amount of the second dephosphorizing agent is controlled so that the basicity of the slag at the end of the dephosphorizing process is 3.5 or less, 3.0 or less, 2.8 or less, or 2.3 or less. May be.
  • the amount of the second dephosphorizing agent at which the basicity of the slag is 1.3 to 4.0 at the end of the process of dephosphorizing the hot metal is determined by the usual method, the initial component of the hot metal, It can be estimated from the components of the two dephosphorizing agents, the components and amounts of additives such as the first dephosphorizing agent, and the amount of oxygen blown into the hot metal.
  • the optimum amount of the second dephosphorizing agent is influenced by the above-mentioned various conditions, but is considered to be 1.0 to 5.0 t under normal conditions.
  • the type of the first dephosphorizing agent and the second dephosphorizing agent is not particularly limited as long as the basicity of the slag can be controlled as described above.
  • quick lime, limestone, calcium ferrite, dolomite lime, and converter slag or secondary refining slag containing at least one selected from those containing CaO, CaO, CaCO 3 , and CaF 2
  • the total content of CaO in an amount of 30 to 100% by mass can be used as one or both of the first dephosphorizing agent and the second dephosphorizing agent.
  • the hot metal dephosphorization method according to the present embodiment may include an additional step.
  • the hot metal after dephosphorization may be further subjected to decarburization refining, and even if this decarburization refining is continuously performed in the furnace where dephosphorization refining is performed, it is different from the furnace where dephosphorization refining was performed. It may be carried out in a furnace.
  • the apparatus for carrying out the hot metal dephosphorization method according to the present embodiment is not particularly limited. From the knowledge of the present inventors, for example, an upper-bottom blowing converter 1 having a lance for blowing a powdery second dephosphorizing agent 5 using a carrier gas, as exemplified in FIG. It is preferable for carrying out the hot metal dephosphorization method according to the present invention.
  • the top-bottom blowing converter 1 When performing dephosphorization refining of hot metal using the top-bottom blowing converter 1, it is preferable to add the second dephosphorizing agent 5 directly below and in the vicinity of the lance 4 for blowing up the blown oxygen 6 into the hot metal.
  • FIG. 3 shows an embodiment in which the second dephosphorizing agent 5 is blown using the lance 4 for blowing the top blowing oxygen 6, another lance for blowing the second dephosphorizing agent 5 is used as the upper bottom. It may be provided in the blow converter 1.
  • converter refining using a top-bottom blowing converter and dephosphorizing, slag removal, and decarburization refining in the same converter reduces the total refining time and further uses the dephosphorizing agent. It is possible to reduce heat loss in refining.
  • the type of carrier gas used when blowing the powdery second dephosphorizing agent into the hot metal is not particularly limited.
  • one or more gases selected from the group consisting of Ar, N 2 , CO 2 , and O 2 are used. It can be used as a carrier gas.
  • N 2 gas In the hot metal at the stage of dephosphorization, since the content of C having a function of preventing N uptake of hot metal is high, even if the second dephosphorizing agent is blown into the hot metal with N 2 , It is considered that the amount of N taken in is small enough to be ignored.
  • the powdery second dephosphorization agent was blown in one of the following stages.
  • the time when the Si content of the hot metal is reduced to 0.10% by mass or less by dephosphorization blowing is referred to as “when de-Si is completed”.
  • First stage (comparative example): 40 seconds before completion of desiliconization
  • Second stage (comparative example): 20 seconds before completion of desiliconization
  • Third stage (invention example): Fourth stage (invention example) immediately after completion of desiliconization: 20 seconds after the completion of desiliconization
  • the above-mentioned fourth stage is before the amount of oxygen blown into the hot metal after the completion of desiliconization is set to 3.0 Nm 3 / t.
  • the operating conditions other than the timing of blowing the second dephosphorizing agent are as follows.
  • -Form of the first dephosphorizing agent a mixture of massive lime, limestone and converter slag (CaO equivalent 25% by mass or more)
  • the form of the second dephosphorizing agent the ratio of the CaO equivalent of the powdered quicklime and the first dephosphorizing agent to the SiO 2 equivalent of the Si content in the initial component of the hot metal: 0.60 to 2.00
  • the experimental results are shown in Tables 1 to 4 and FIGS.
  • the values shown in Tables 1 to 4 are experimental results in the first to fourth stages.
  • the “lumped CaO” column and the “powder CaO” column indicate the input amounts of the first dephosphorizing agent and the second dephosphorizing agent, respectively.
  • the “initial component Si content” is the Si content in the hot metal initial component (the component before the start of dephosphorization blowing).
  • 4 to 6 are graphs of the data shown in Tables 1 to 4.
  • the horizontal axis of the graph shown in FIG. 4 shows the basicity of charging (the molten iron and the additive Si are all SiO 2 , and the first and second dephosphorizing agents Ca are all molten CaO. Slag basicity), and the vertical axis represents the dephosphorization rate.
  • Dephosphorization rate is the amount of decrease in P content by dephosphorization (subtracting the measured value of P content of hot metal after dephosphorization from the measured value of P content of hot metal before dephosphorization) (Value) divided by the measured value of the P content of the hot metal before dephosphorization, that is, a calculated value by the following equation.
  • Dephosphorization rate ([P] i ⁇ [P] f) / [P] i
  • [P] i is a measurement value of the P content of the hot metal before dephosphorization blowing
  • [P] f is a measurement value of the P content of the hot metal after dephosphorization blowing.
  • FIG. 5 The horizontal axis of the graph shown in FIG. 5 is the charging basicity, and the vertical axis is the slag basicity after dephosphorization (value obtained by measuring the basicity of slag collected after dephosphorization). is there.
  • FIG. 6 is a graph showing the average hatching rate in the first to fourth stages. As described above, the value obtained by dividing the slag basicity after dephosphorization by the charged basicity is the hatching rate, and the average hatching rate in each of the first to fourth stages is expressed as the first to fourth stages. The average hatching rate for each of the four stages is used.
  • the dephosphorization rate of the inventive example was remarkably improved as compared with the comparative example obtained by the conventional dephosphorization method. Further, as shown in FIGS. 5 and 6, the hatching rate of the inventive example was remarkably improved as compared with the comparative example by the conventional dephosphorization method.
  • the hatching rate of the dephosphorizing agent is high and the hot metal dephosphorization efficiency is excellent. Therefore, the hot metal dephosphorization method according to the present invention can sufficiently dephosphorize the hot metal without increasing the amount of slag, so that high-grade steel with a low P content can be produced with a low environmental load. For the reasons described above, the present invention has extremely high industrial applicability.

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  • Carbon Steel Or Casting Steel Manufacturing (AREA)

Abstract

L'invention concerne un procédé de déphosphoration pour du fer en fusion selon un mode de réalisation et comprend une étape consistant à mesurer la quantité de Si contenue dans un composant initial du fer en fusion, une étape consistant à injecter un premier agent de déphosphoration dans le fer en fusion, et une étape consistant à soumettre le fer en fusion à un soufflage de déphosphoration. Pendant l'étape de soufflage de déphosphoration, un second agent de déphosphoration pulvérulent est également injecté dans le fer en fusion, et l'injection du second agent de déphosphoration est démarrée après que la teneur en Si dans le fer en fusion a été amenée à 0,10 % en masse ou moins par le soufflage de déphosphoration et avant que la quantité d'oxygène soufflée dans le fer en fusion atteigne 3,0 Nm3/t.
PCT/JP2019/008447 2018-03-07 2019-03-04 Procédé de déphosphoration pour fer en fusion Ceased WO2019172195A1 (fr)

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CN114959180B (zh) * 2022-06-15 2024-02-06 首钢集团有限公司 一种脱磷粉剂及其应用

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CN114807513B (zh) * 2022-04-18 2023-09-08 攀枝花市蓝天锻造有限公司 一种提高脱磷效率的方法及其应用

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TWI683000B (zh) 2020-01-21
JPWO2019172195A1 (ja) 2020-12-17
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