WO2018123666A1 - 溶銑の脱燐方法及び精錬剤 - Google Patents
溶銑の脱燐方法及び精錬剤 Download PDFInfo
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- WO2018123666A1 WO2018123666A1 PCT/JP2017/045197 JP2017045197W WO2018123666A1 WO 2018123666 A1 WO2018123666 A1 WO 2018123666A1 JP 2017045197 W JP2017045197 W JP 2017045197W WO 2018123666 A1 WO2018123666 A1 WO 2018123666A1
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- hot metal
- dephosphorization
- refining agent
- mass
- oxygen source
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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
- 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
-
- 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
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/02—Dephosphorising or desulfurising
- C21C1/025—Agents used for 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
- C21C5/42—Constructional features of converters
- C21C5/46—Details or accessories
- C21C5/4606—Lances or injectors
-
- 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
-
- 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
- C21C7/0037—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00 by injecting powdered material
-
- 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
- C21C7/0075—Treating in a ladle furnace, e.g. up-/reheating of molten steel within the ladle
-
- 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
-
- 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
- C21C7/072—Treatment with gases
-
- 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
- C21C7/076—Use of slags or fluxes as treating agents
-
- 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
- C21C2200/00—Recycling of waste material
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- 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 and a refining agent.
- an oxygen source such as gaseous oxygen (oxygen gas) or solid iron oxide is supplied to the hot metal as a dephosphorizing agent, and the phosphorus in the hot metal is oxidized with oxygen in the dephosphorizing agent to obtain a phosphorus oxide (P 2 O 5 ), and the produced phosphorus oxide is absorbed into the slag for dephosphorization refining.
- oxygen gas gaseous oxygen
- solid iron oxide solid iron oxide
- a lime refining agent As a refining agent for forming slag for dephosphorization refining, a lime refining agent is generally used. In recent years, it has been demanded to reduce slag generated in the steelmaking process from the viewpoint of environmental protection measures. However, since the dephosphorization of hot metal is a low temperature treatment advantageous for the dephosphorization reaction, relatively little slag is produced. Can be processed in quantity.
- Such hot metal dephosphorization is performed by adding a refining agent to the hot metal in the converter and blowing up gaseous oxygen, or by dephosphorizing or dephosphorizing the hot metal contained in a kneading car or hot metal pan. Processes are selected and implemented according to the facilities and environment of each steelworks, such as the method of blowing smelting agent and smelting agent.
- the method using a converter has the advantage that hot metal with low phosphorus concentration can be produced in a short time because gaseous oxygen can be blown onto the hot metal at a high flow rate, but the existing converter capacity If there is no allowance and a new installation is required, high equipment costs are required.
- the progress of decarburization is unavoidable, and there is a problem of a decrease in thermal margin in the subsequent process due to a decrease in the carbon concentration of the hot metal.
- the method of using a kneading car or hot metal ladle is a process that uses an existing hot metal transfer container, so the equipment cost is low, and even if there is no margin in the converter capacity, you can enjoy the benefits of hot metal dephosphorization.
- iron oxide which is a dephosphorizing agent
- a refining agent are blown into the bath to ensure contact between the iron oxide and the refining agent in the bath, thereby promoting the hatching of the refining agent and the dephosphorization reaction. It aims to make it.
- simply injecting iron oxide and a refining agent has few opportunities for contact between the iron oxide and the refining agent.
- the meltability of slag can be obtained by using a CaF 2 -based solvent such as fluorite as a hatching accelerator for a refining agent.
- a technique for improving the dephosphorization reactivity has been widely used.
- Patent Document 1 the use of a CaF 2 -based solvent such as fluorite as a hatching accelerator for a refining agent improves the meltability of the slag for dephosphorization refining reaction.
- a technique for improving the performance has been proposed.
- CaF 2 based medium solvent such as fluorite development of a method capable of performing highly efficient dephosphorization has been strongly desired.
- Patent Document 2 as a method of efficiently dephosphorizing without using a CaF 2 -based solvent, iron oxide is added from above the bath surface to the hot metal held in the hot metal holding container.
- the iron oxide bath injection area is 40% or more of the blowing area on the lime refining agent bath area in terms of area ratio.
- a method of dephosphorizing by adding iron oxide so as to wrap is proposed.
- Patent Document 3 discloses that hot oxygen held in a hot metal holding container is sprayed with gaseous oxygen from above the bath surface, and a lime refining agent or a lime refining agent and a solid dephosphorizing agent are provided below the bath surface.
- dephosphorization treatment is performed by blowing (iron oxide) together with the carrier gas, the blowing strength of the gaseous oxygen is within a predetermined level, and the blowing position of the gaseous oxygen blowing position and the carrier gas blowing surface
- a method for promoting the hatching and dephosphorization reaction of a lime-based refining agent by specifying the positional relationship of the above has been proposed.
- the present invention has been made paying attention to the above-mentioned problems, and provides a hot metal dephosphorization method and a refining agent capable of increasing the dephosphorization efficiency without using a CaF 2 -based solvent. It is an object.
- a hot metal dephosphorization method characterized by using a refining agent having an Ig-loss value of 4.0% by mass or more and 35.0% by mass or less and containing 60% by mass or more of quicklime.
- a refining agent having an Ig-loss value of 4.0% by mass or more and 35.0% by mass or less containing quick lime 60% by mass or more and used for dephosphorization treatment of hot metal.
- a hot metal dephosphorization method and a refining agent capable of improving the dephosphorization efficiency without using a CaF 2 -based solvent.
- the CaF 2 -based solvent plays an important role in ensuring the meltability of the slag, and the CaF 2 -based solvent is not used in our experiments. In some cases, it was confirmed that the added refining agent was not hatched apparently and the dephosphorization reaction efficiency was lowered.
- the present inventors remarkably improved the dephosphorization efficiency by adding a lime-based refining agent having an Ig-loss value of 4.0% by mass or more and 35.0% by mass or less while repeating the experiment. Furthermore, when this refining agent is blown together with the carrier gas from an injection lance immersed in hot metal, the dephosphorization efficiency is further improved by satisfying equations (1) to (3), and the present invention has been developed. It came to do. Ig-loss (ignition loss, ignition loss) is measured as a weight loss (derived from volatile matter such as H 2 O and CO 2 ) when the sample is ignited to a constant weight at 1050 ⁇ 50 ° C. .
- ⁇ g is the carrier gas stirring power [W / t]
- ⁇ P is the energy of the lime source
- Q is the carrier gas flow rate [Nm 3 / min] (where N and Means the standard state of gas of 101325 Pa, 273.15 K.)
- W is the amount of hot metal [t]
- T 1 is the hot metal temperature [° C.]
- T g is the temperature of the carrier gas [° C.]
- h is the injection lance. immersion depth of the [m]
- P is atmospheric pressure [Pa]
- m is the speed blowing lime source [g / s]
- d 0 is the nozzle diameter of the injection lance [cm].
- Ig. Loss is ignition loss (Ig-loss value) [mass%]
- m 0 is the mass of the sample of the refining agent before heating [g]
- m 1 is the weight loss of the sample [g].
- the hot metal dephosphorization method and refining agent based on one Embodiment of this invention based on the said knowledge are demonstrated.
- the hot metal 2 is dephosphorized using the hot metal holding container 1, which is a hot metal ladle, as a reaction container.
- the hot metal 2 is extracted from the blast furnace, and may be subjected to desiliconization treatment before dephosphorization treatment.
- a method of spraying oxygen gas onto the hot metal 2 or a method of adding an oxidant containing solid oxygen such as iron oxide to the hot metal 2 in a blast furnace casting bed or hot metal transfer container is used. May be.
- the hot metal 2 is dephosphorized using the dephosphorization equipment shown in FIG.
- the processing facility includes an injection lance 3, an upper blowing lance 4, and an input chute 5.
- the injection lance 3 is a lance that extends in the vertical direction (vertical direction in FIG. 1), and is arranged so that the central axis substantially overlaps the center of the hot metal holding container 1 in plan view. Further, the injection lance 3 is configured such that the upper end side in the vertical direction is connected to a lifting device (not shown) and can be lifted and lowered in the vertical direction.
- the injection lance 3 has an inner hole extending in the vertical direction inside, and has two discharge ports that communicate with the inner hole on the outer peripheral surface on the lower end side in the vertical direction and face each other in the radial direction of the injection lance 3. .
- the injection lance 3 is supplied with a carrier gas 6 and a smelting agent 7 as a lime source from a refining agent supply device (not shown) from the upper end side of the inner hole.
- the injection lance 3 has the carrier gas 6 and the refining agent 7 supplied from the refining agent supply device in a state where the lower end side is immersed below the bath surface of the hot metal 2. It blows into the hot metal 2 from two discharge ports.
- the carrier gas 6 is an inert gas (inert gas such as Ar gas or N 2 gas), compressed air, or the like, assisting the transportation of the refining agent 7 until it is blown into the hot metal, and stirring the hot metal 2.
- the refining agent 7 is a lime-based refining agent mainly composed of CaO, containing 60% or more of CaO, and having an Ig-loss value of 4.0% by mass or more and 35.0% by mass or less.
- the refining agent 7 preferably has a particle size of 2 mm or less. By setting the particle size of the refining agent 7 to 2 mm or less, the melting (hatching) speed of the refining agent 7 is improved.
- the refining agent 7 blown into the hot metal 2 melts (incubates) with the heat of the hot metal 2 while floating in the hot metal 2 to form a slag 8 that floats on the bath surface of the hot metal 2.
- the refining agent 7 preferably has a total pore volume of 0.1 mL / g or more of pores having a pore diameter ranging from 0.5 ⁇ m to 10 ⁇ m. Thereby, since melting of CaO is further promoted, the dephosphorization efficiency can be further improved. Furthermore, the specific surface area of the refining agent 7 is desirably 0.5 m 2 / g or more and 5 m 2 / g or less. The specific surface area of the refining agent 7 can be measured by, for example, the BET method (multipoint method). In this measurement method, for example, as a pretreatment, vacuum deaeration is performed at 120 ° C. for 8 hours using a BELPREP-vac II apparatus.
- the BET method multipoint method
- the specific surface area is calculated by measuring an adsorption isotherm by nitrogen using a low volume method.
- the adsorption temperature is 77 K
- the adsorbate cross-sectional area is 0.162 nm 2
- the saturated vapor pressure is an actual measurement value.
- the equilibrium waiting time after reaching the adsorption equilibrium state where the pressure change during adsorption / desorption becomes a predetermined value or less is set to 500 seconds.
- the injection lance 3 is configured so that a mixture of quick lime having an Ig-loss value of 4.0% by mass or less as a lime source mixed with the refining agent 7 is blown into the molten iron 2 together with the carrier gas 6 as necessary. May be.
- the upper blowing lance 4 is a lance arranged above the hot metal holding container 1 and jets gas or powder from two nozzles provided at the lower end. In the present embodiment, the upper blowing lance 4 is formed with two different paths: a path for supplying the gaseous oxygen source 9 and a path for supplying the carrier gas 10 and the dephosphorizing agent 11.
- the upper ends of the upper blowing lances 4 of these two paths are connected to a supply device (not shown) for the gaseous oxygen source 9 and a supply device (not shown) for the carrier gas 10 and the dephosphorization agent 11, respectively.
- a carrier gas 10 including a gaseous oxygen source 9 and a dephosphorization agent 11 supplied from these supply devices is supplied from the two nozzles provided at the lower end of the upper blowing lance 4 to the bath surface of the hot metal 2 below in the vertical direction. Each is injected toward.
- the gaseous oxygen source 9 is an oxygen source in the dephosphorization process, and oxidizes phosphorus in the hot metal 2.
- oxygen gas including industrial pure oxygen
- air oxygen-enriched air
- it is preferable to use oxygen gas because the dephosphorization reaction rate is faster than when other gases are used.
- oxygen concentration higher than air, in order to ensure the dephosphorization reaction rate.
- the carrier gas 10 injected from the top blowing lance 4 may be the same gas as the carrier gas 6 blown from the injection lance 3 or may be oxygen gas.
- the dephosphorizing agent 11 injected from the top blowing lance 4 is a solid oxygen source including an iron oxide source, and is made of iron ore, mill scale, iron sand, dust collection dust (from exhaust gas in a blast furnace, converter, sintering process, etc.) Recovered iron-containing dust).
- the dephosphorizing agent 11 is preferably in the form of fine powder having a particle size of 1 mm or less, and it is more preferable that the dephosphorizing agent 11 is iron sand or fine powdered iron ore having a particle size of 1 mm or less because there is no need for pulverization treatment.
- iron sand not only functions as a solid oxygen source, but also has a function as a hatching accelerator of the refining agent 7 mainly composed of CaO since it contains about 7 to 10% by mass of titanium oxide. It is particularly suitable
- the charging chute 5 is a chute arranged vertically above the hot metal holding container 1 and adds a dephosphorizing agent 12 cut out from a hopper (not shown) to the bath surface of the hot metal 2.
- the dephosphorizing agent 12 added from the charging chute 5 is a solid oxygen source containing an iron oxide source, like the dephosphorizing agent 11 injected from the top blowing lance 4.
- a dephosphorizing agent 12 having a particle diameter larger than that of the dephosphorizing agent 11 injected from the top blowing lance 4 may be used as the dephosphorizing agent 12 added from the charging chute 5.
- gaseous oxygen source 9 injected from the top blowing lance 4 and the dephosphorizing agent 11 as the solid oxygen source, and the dephosphorizing agent 12 as the solid oxygen source added from the charging chute 5 are collectively referred to as an oxygen source. .
- the hot metal holding container 1 in which the hot metal 2 is accommodated is disposed at a predetermined processing position of the dephosphorization processing facility shown in FIG. 2 is immersed under the bath surface.
- the carrier gas 6 and the refining agent 7 are blown from the injection lance 3 into the molten iron 2, the gaseous oxygen source 9, the carrier gas 10 and the dephosphorizing agent 11 are injected from the top blowing lance 4, and the charging chute 5
- the dephosphorization agent 11 is added (dephosphorization process).
- the hot metal holding vessel 1 is used as a reaction vessel, and a refining agent 7 which is a lime source mainly composed of CaO and a solid oxygen source which is a gaseous oxygen source 9 and dephosphorizing agents 11 and 12 are added to the hot metal 2.
- a refining agent 7 which is a lime source mainly composed of CaO and a solid oxygen source which is a gaseous oxygen source 9 and dephosphorizing agents 11 and 12 are added to the hot metal 2.
- the refining agent 7 hatches to form a slag 8 that floats on the bath surface of the molten iron 2.
- the oxygen source generates phosphorus oxide by oxidizing phosphorus in the hot metal 2.
- the produced phosphorous oxide is taken into the slag 8 to remove phosphorus from the hot metal 2.
- the stirring power of the hot metal 2 is preferably set to 300 W / t or more in order to obtain sufficient stirring properties. Moreover, if the stirring of the hot metal 2 is too strong, there is a possibility that the generated FeO will reduce the carbon in the hot metal 2 too much, so the stirring power of the hot metal 2 is preferably 1000 W / t or less.
- the dephosphorization treatment is performed by blowing the refining agent 7 as a lime source together with the carrier gas 6 from the injection lance 3 into the hot metal 2 as in this embodiment, the conditions satisfying the above formulas (1) to (3) are satisfied. It is preferable to blow in the carrier gas 6 and the lime source. By setting the conditions to satisfy the formulas (1) to (3), the hot metal 2 is stirred with a sufficient stirring property, so that the dephosphorization process can be performed efficiently.
- the immersion depth h of the injection lance 3 is preferably 1.5 m or more. When the immersion depth h is less than 1.5 m, the gas blows out and the molten iron 2 is scattered violently.
- the reaction shown in the following formulas (5) and (6) occurs, thereby generating H 2 O gas and CO 2 gas.
- the hatching of CaO is promoted.
- the Ig-loss value is 4.0 mass% or more and 35.0 mass% or less, H 2 O gas and CO 2 gas are appropriately generated and hatching is promoted.
- Dephosphorization reaction is promoted.
- the Ig-loss value is less than 4.0% by mass, the generation of H 2 O gas and CO 2 gas is reduced, so that a sufficient effect of improving the dephosphorization efficiency cannot be obtained.
- the Ig-loss value exceeds 35.0% by mass, the CaO pure content in the refining agent 7 is reduced, so that a sufficient effect of improving the dephosphorization efficiency cannot be obtained.
- quick lime having an Ig-loss value of less than 4.0 mass% may be mixed and blown into the refining agent 7 as a lime source.
- the ratio of the refining agent 7 is 20% by mass or more in what is blown as the lime source.
- the ratio of the refining agent 7 is less than 20% by mass, the effect of promoting the hatching of CaO is reduced, and thus the effect of improving the dephosphorization efficiency is reduced.
- the Si concentration of the hot metal 2 is as high as 0.40% by mass or more, the slag 8 may be ejected from the hot metal holding container 1 due to forming (foaming phenomenon). For this reason, when forming occurs, it is necessary to reduce the acid feed rate at which the oxygen source is added, leading to a reduction in productivity. However, by blowing the refining agent 7 from the injection lance 3 into the molten iron 2, the slag 8 is degassed by the generated gas such as CO 2 or H 2 O, and therefore, the forming of the slag 8 can be suppressed.
- the basicity of the slag 8 after the dephosphorization treatment (the mass ratio of CaO to SiO 2 in the slag, [% CaO] / [% SiO 2 ]) is set to 1.8 or more and 3. It is desirable to control to about 5 or less.
- the addition amount of the refining agent 7 is appropriately determined according to the component of the hot metal 2 before the dephosphorization of the hot metal 2, the component of the hot metal 2 after the target dephosphorization, the amount of the hot metal 2, and the like.
- the gaseous oxygen source 9 injected from the upper blowing lance 4 is sprayed on the bath surface of the hot metal 2.
- the bath surface region (fire point) of the hot metal 2 to which the gaseous oxygen source 9 is sprayed is a bath surface region in which the refining agent 7 blown from the injection lance 3 rises as shown in FIG. It is preferable to superimpose.
- the decarburization reaction by the gaseous oxygen source 9 is dominant at the fire point, and due to heat generation such as the decarburization reaction, the dephosphorization process normally becomes a high temperature exceeding 2000 ° C.
- hatching of the refining agent 7 is further promoted by superimposing the position of the fire point on the bath surface position to which the refining agent 7 is supplied.
- the dephosphorization reaction is promoted at a lower temperature in terms of thermodynamics, and therefore, the reaction occurs at a peripheral portion of about 1800 ° C. or less, slightly away from the fire point.
- the reactions shown in the equations (5) and (6) for the refining agent 7 are endothermic reactions, the position of the fire point is superimposed on the bath surface position to which the refining agent 7 is supplied.
- a cooling effect of the hot spot is also obtained. For this reason, it is possible to further promote the dephosphorization reaction.
- the dephosphorization agents 11 and 12 which are solid oxygen sources are added to the hot metal 2 by blowing from the top blowing lance 4 and charging from the charging chute 5.
- the oxygen source contributing to the dephosphorization reaction is more solid than the gaseous oxygen source 9 as the solid oxygen source. Increases efficiency.
- the temperature rise due to decarburization heat generation becomes dominant.
- the temperature rise is suppressed because heat is absorbed during decomposition of the solid oxygen source.
- the solid oxygen source by using a solid oxygen source, it is possible to maintain a temperature advantageous for the dephosphorization reaction.
- a temperature condition that can melt the solid oxygen source is necessary.
- the solid oxygen source becomes FeO after melting and has a function of increasing the FeO component in the slag 8 which contributes to the dephosphorization reaction. To promote.
- the dephosphorization agent 11 injected together with the carrier gas 10 from the top blowing lance 4 is sprayed near the hot spot of the bath surface where the gaseous oxygen source 9 is injected as shown in FIG. Is preferred.
- the dephosphorization agent 11 which is a solid oxygen source added from the top blowing lance 4 is supplied to a region close to the fire point where the dephosphorization reaction is substantially promoted.
- the dephosphorizing agent 11 is supplied by a carrier gas 10 having a lower oxygen concentration than the gaseous oxygen source 9. For this reason, since the temperature of the region to which the dephosphorizing agent 11 is supplied does not rise excessively, dephosphorization is further promoted by the good reactivity of the dephosphorizing agent 11. For example, the dephosphorization capacity at 1800 ° C. is almost doubled compared to the dephosphorization capacity at 2000 ° C. by thermodynamic estimation.
- the addition amount of the solid oxygen source which is the total addition amount of the dephosphorization agent 11 and the dephosphorization agent 12, is not accelerated when the increase in the FeO concentration in the slag 8 is reduced. It is sufficient that the amount of FeO is sufficiently large.
- the upper limit of the addition amount of the solid oxygen source may be an amount that does not cause the problem of heat removal by the solid oxygen source according to the equipment specifications. For example, when dephosphorization is performed in the hot metal holding container 1 of about 100 ton to 350 ton, the solid oxygen source is 0.1 kg with respect to 1 Nm 3 of pure oxygen gas in the standard state of the gaseous oxygen source 9 supplied to the bath surface. It is preferable to add in the range of 2 kg or less.
- addition amount of the solid oxygen source When the addition amount of the solid oxygen source is less than 0.1 kg, the effect expected in this treatment mode cannot be obtained sufficiently. On the other hand, when the addition amount of the solid oxygen source exceeds 2 kg, the heat removal on the supply surface of the solid oxygen source becomes large, the hatching of the slag 8 becomes insufficient, and the dephosphorization ability decreases.
- a more preferable addition amount of the solid oxygen source is 0.3 kg or more and 2 kg or less.
- the ratio of the dephosphorizing agent 11 added from the top blowing lance 4 and the dephosphorizing agent 12 added from the charging chute 5 is appropriately determined according to the addition amount of the solid oxygen source, equipment specifications, and the like.
- the addition amount of the dephosphorizing agent 11 is set so that the dephosphorizing efficiency is maximized. It is preferable that the maximum amount that can be added during the dephosphorization treatment is set, and the additional amount of the solid oxygen source that is necessary is set as the addition amount of the dephosphorization agent 12. In this case, if the addition of the dephosphorizing agent 11 from the top blowing lance 4 is sufficient, the addition of the dephosphorizing agent 12 from the charging chute 5 may not be performed.
- the use ratio of the solid oxygen source and the gaseous oxygen source 9 is set according to the temperature before and after the treatment of the hot metal 2 while maintaining the above range.
- the FeO concentration in the slag 8 is preferably in the range of 10% by mass to 50% by mass, and in the range of 10% by mass to 30% by mass. More suitable. For this reason, it is preferable to adjust the supply amount or supply speed of the solid oxygen source so that the FeO concentration in the slag 8 is maintained within this range as much as possible during the dephosphorization process.
- the process is completed until the temperature / component of the hot metal 2 reaches the target or the oxygen source is added in a preset amount.
- the addition of the gaseous oxygen source 9 and the dephosphorization agent 11 by the top blowing lance 4 and the addition of the dephosphorization agent 12 from the charging chute 5 do not need to be performed continuously over the entire period of the dephosphorization process, and are intermittent. Addition may be made.
- the addition of the refining agent 7 from the injection lance 3 may be continuously performed, the blowing of the carrier gas 6 for the purpose of stirring the molten metal 2 is continuously performed over the entire period of the dephosphorization process. It is preferable.
- the hot metal holding container 1 is a hot metal ladle, but the present invention is not limited to such an example.
- the hot metal holding container 1 is not limited as long as it can accommodate the hot metal 2 and can be processed by the same dephosphorization equipment as described above.
- the hot metal holding container 1 may be a container such as a topped car that is a hot metal transfer container.
- the carrier gas 6 and the refining agent 7 are blown from the injection lance 3, and the gaseous oxygen source 9, the carrier gas 10, and the dephosphorization agent 11 as the solid oxygen source are blown from the top blowing lance 4.
- the dephosphorization agent 12 that is a solid oxygen source is blown from the chute 5, the present invention is not limited to such an example.
- the oxygen source only one of the solid oxygen source and the gaseous oxygen source 9 may be used.
- both the solid oxygen source and the gaseous oxygen source 9 are used from the viewpoint of promoting the hatching and dephosphorization of the refining agent 7. It is preferable.
- the solid oxygen source may be supplied only from the top blowing lance 4 or may be added only from the charging chute 5.
- the solid oxygen source is preferably added (projected) together with the carrier gas 10 from the top blowing lance 4 because the dephosphorization promoting effect is obtained by improving the oxygen potential of the slag 8 and cooling the fire point.
- the solid oxygen source should be added near the hot spot of the bath surface of the hot metal 2 for the same reason as when charging from the top blowing lance 4. Is preferred.
- the solid oxygen source may be blown together with the carrier gas 6 from the injection lance 3.
- the dephosphorizing agent that is a solid oxygen source blown from the injection lance 3 may have the same configuration as the dephosphorizing agents 11 and 12 of the above embodiment.
- only the solid oxygen source may be blown from the injection lance 3 together with the carrier gas 6, or the solid oxygen source and the refining agent 7 may be blown together with the carrier gas 6.
- the refining agent 7 may be added from the charging chute 5 or may be added together with the carrier gas 10 from the upper blowing lance 4.
- the gaseous oxygen source 9 may be blown from the injection lance 3.
- the gaseous oxygen source 9 may be blown from only the injection lance 3 or may be blown from both the upper blow lance 4 and the injection lance 3.
- at least one of the refining agent 7 and the solid oxygen source may be blown from the injection lance 3 simultaneously with the gaseous oxygen source 9.
- the refining agent 7 may be added to the hot metal 2 from the top blowing lance 4 or the charging chute 5.
- the refining agent 7 when the refining agent 7 is added from the top blowing lance 4, the refining agent 7 is injected into the hot metal 2 together with the carrier gas 10 in the same manner as when the dephosphorizing agent 11 is added.
- the refining agent 7 added from the top blowing lance 4 or the input chute 5 may have an Ig-loss value of 4.0% by mass or more and 35.0% by mass or less. It may be different from the embodiment.
- the hot metal 2 was stirred with the carrier gas 6 blown from the injection lance 3
- this invention is not limited to this example.
- a configuration may be adopted in which the hot metal 2 is stirred by embedding a nozzle in the furnace bottom of the hot metal holding container 1 and blowing a stirring gas similar to the carrier gas 6 into the hot metal 2 from this nozzle.
- the phosphorus removal treatment may be performed using at least one of the upper blowing lance 4 and the charging chute 5 without using the injection lance 3. Good.
- the oxygen source and the refining agent 7 are added to the hot metal 2 using at least one of the top blowing lance 4 and the charging chute 5.
- the hot metal 2 accommodated in the hot metal holding container 1 is supplied with a refining agent 7 and an oxygen source (dephosphorizing agents 11 and 12 and gaseous oxygen).
- the refining agent 7 has an Ig-loss value of 4.0% by mass or more and 35.0% by mass or less, and quick lime is 60% by mass or more. Use what is included.
- the configuration of (1) above when dephosphorization is performed using the lime-based refining agent 7 having excellent reactivity, H 2 O gas and CO 2 gas are appropriately generated, and hatching is promoted. Therefore, the dephosphorization reaction is promoted.
- the specific surface area of the refining agent 7 is 0.5 m 2 / g or more and 5 m 2 / g or less. According to the configuration of (3) above, the wettability between the hot metal 2 and the refining agent 7 is improved, so that the dephosphorization efficiency can be further improved.
- the dephosphorization efficiency can be further improved by using only the refining agent 7 having high reactivity and excellent hatchability as a lime source.
- the refining agent according to one embodiment of the present invention has an Ig-loss value of 4.0% by mass or more and 35.0% by mass or less, includes quick lime 60% by mass or more, and is used for hot metal dephosphorization treatment. . According to the configuration of (5), the same effect as the configuration of (1) can be obtained.
- Example 1 performed by the present inventors will be described.
- dephosphorization treatment was performed by changing the Ig-loss value of the lime source as the refining agent 7, and the influence of the Ig-loss value on the dephosphorization rate was investigated. did.
- the hot metal 2 discharged from the blast furnace and desiliconized in the blast furnace casting floor was transferred to a hot metal ladle having a capacity of 250 tons as the hot metal holding container 1, and the dephosphorization process shown in FIG. Transported to equipment.
- the refining agent lime source is blown from the injection lance 3
- the gaseous oxygen source 9 and the dephosphorizing agent 11 are injected from the top blowing lance 4
- the dephosphorizing agent 12 from the charging chute 5 is injected.
- the dephosphorization process was performed by adding. Prior to the dephosphorization treatment, the silicon concentration of the hot metal 2 was 0.15 mass%, the carbon concentration was 4.5 mass%, and the phosphorus concentration was 0.121 mass% to 0.125 mass%.
- Example 1 as a solid oxygen source for the dephosphorization agents 11 and 12, sand iron having an average particle diameter of 500 ⁇ m was added in a total amount of 10 kg / t (amount per ton of hot metal) from the top blowing lance 4 and the charging chute 5.
- an inert gas was used as the carrier gas 10.
- a gaseous oxygen source 9 was sprayed onto the hot metal 2 at an acid feed rate of 1500 Nm 3 / hr to 2000 Nm 3 / hr.
- the lance height of the upper blowing lance 4 (the distance from the lower end of the upper blowing lance 4 to the bath surface of the hot metal 2) was set to 1.0 m to 1.5 m.
- the lime source 50% by mass of lime-based refining agent 7 and 50% by mass of quick lime were used.
- the refining agent 7 had an Ig-loss value of 4.0 mass% to 35.0 mass% and a specific surface area of 0.41 to 0.42 m 2 / g.
- an inert gas is used as the carrier gas 6
- the stirring power ( ⁇ g + ⁇ P ) that is the sum of the stirring power of the carrier gas and the energy of the lime source shown in Formula (1). was 265 W / t.
- the dephosphorization processing time which is the processing time for supplying a predetermined amount of oxygen source to the hot metal 2, was set to 15 to 25 minutes.
- the basicity of slag was adjusted to be 2.0.
- Example 1 As a comparison, the dephosphorization treatment was performed under the condition that the Ig-loss value of the refining agent 7 was different from that of the above embodiment (Comparative Example 1).
- the Ig-loss value was set to 3.0% by mass or less or 36.0% by mass or more, and the other dephosphorization treatment conditions were the same as in Example 1.
- Table 1 shows the stirring power and refining agent conditions in Example 1, and the phosphorus concentration and dephosphorization rate in the hot metal 2 before and after the treatment, which is the investigation result (the phosphorus in the hot metal 2 was removed before and after the dephosphorization treatment). Ratio). As shown in Table 1, it was confirmed that the dephosphorization rate was as high as 60% or higher under any condition.
- Example 2 performed by the present inventors will be described.
- dephosphorization treatment was performed by changing the stirring power ( ⁇ g + ⁇ P ) of the formula (2), and the influence of the stirring power on the dephosphorization rate was investigated.
- dephosphorization treatment was performed under the same conditions as in Example 1-11 with the stirring power ( ⁇ g + ⁇ P ) changed from 265 W / t to 1392 W / t.
- the phosphorus concentration of the hot metal 2 before the dephosphorization treatment was 0.121% by mass to 0.125% by mass.
- the other conditions are the same as in Example 1-14.
- Table 2 shows the stirring power and the conditions of the refining agent in Example 2, and the phosphorus concentration and dephosphorization rate in the hot metal 2 before and after the treatment, which is the investigation result.
- the dephosphorization rate is as high as 76% or higher under any condition, but the dephosphorization rate is reduced by setting the stirring power ( ⁇ g + ⁇ P ) in the range of 300 W / t to 1000 W / t. Further improvement was confirmed.
- Example 3 performed by the present inventors will be described.
- the dephosphorization treatment was performed by changing the specific surface area of the refining agent 7, and the influence of the specific surface area of the refining agent 7 on the dephosphorization rate was investigated.
- each received dephosphorization by changing the specific surface area of the refining agent 7 to 0.41m 2 /g ⁇ 5.13m 2 / g.
- the phosphorus concentration of the hot metal 2 before the dephosphorization treatment was 0.121% by mass to 0.125% by mass.
- the other conditions are the same as in Example 2-3.
- Table 3 shows the stirring power and the conditions of the refining agent in Example 3, and the phosphorus concentration and dephosphorization rate in the hot metal 2 before and after the treatment, which is the result of the investigation.
- the dephosphorization rate is as high as 80% or higher under any condition, and the dephosphorization rate is further improved by setting the specific surface area in the range of 0.5 m 2 / g to 5 m 2 / g. I was able to confirm.
- Example 4 with respect to the dephosphorization method according to the above embodiment, dephosphorization treatment was performed by changing the ratio of the refining agent 7 in the lime source and the stirring power, and the ratio of the refining agent 7 and the stirring power became the dephosphorization rate. The effect was investigated.
- Example 4 under the same conditions as in Example 3-5, the stirring power was changed to 457 W / t or 726 W / t, and the ratio of the refining agent 7 in the lime source was changed from 50% to 100%. Processed.
- the phosphorus concentration of the hot metal 2 before the dephosphorization treatment was 0.124 mass% to 0.126 mass%.
- Other conditions are the same as in Example 3-5.
- Table 4 shows the stirring power and the conditions of the refining agent in Example 4, and the phosphorus concentration and dephosphorization rate in the hot metal 2 before and after the treatment as the investigation results.
- the dephosphorization rate is as high as 85% or higher under any condition, and with any stirring power condition, the ratio of the refining agent 7 in the lime source blown from the injection lance 3 increases. It was confirmed that the dephosphorization rate was further improved.
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Abstract
Description
そこで、本発明は、上記の課題に着目してなされたものであり、CaF2系媒溶剤を用いなくとも、脱燐処理効率を高めることができる溶銑の脱燐方法及び精錬剤を提供することを目的としている。
本発明の一態様にれば、Ig-loss値が4.0質量%以上35.0質量%以下であり、生石灰を60質量%以上含み、溶銑の脱燐処理に用いられる精錬剤が提供される。
はじめに、本発明に先立ち、本発明者らは、ホタル石などのCaF2系媒溶剤を石灰系の精錬剤の滓化促進剤として使用しなくとも、高効率な脱燐処理を行うことのできる方法を見出すべく、取鍋型の溶銑保持容器を用いて種々の実験、検討を行った。その結果、先に述べたように、CaF2系媒溶剤はスラグの溶融性を確保する上で重要な働きをしており、本発明者らの実験においても、CaF2系媒溶剤を併用しない場合には、添加された精錬剤は見かけ上からも滓化しておらず、脱燐反応効率も低下することを確認した。
図1を参照して、上記知見に基づいた本発明の一実施形態に係る溶銑の脱燐方法及び精錬剤について説明する。本実施形態では、図1に示すように、溶銑鍋である溶銑保持容器1を反応容器として用いて溶銑2の脱燐処理を行う。
溶銑2は、高炉から出銑されたものであり、脱燐処理の前に予め脱珪処理が施されてもよい。予め施される脱珪処理としては、例えば、高炉の鋳床や溶銑搬送容器内で、酸素ガスを溶銑2に吹き付ける方法や酸化鉄等の固体酸素を含む酸化剤を溶銑2に添加する方法が用いられてもよい。
インジェクションランス3は、鉛直方向(図1の上下方向)に延在して配されるランスであり、平面視で中心軸が溶銑保持容器1の中心と略重なるように配される。また、インジェクションランス3は、鉛直方向の上端側が不図示の昇降装置に接続され、鉛直方向に昇降可能に構成される。さらに、インジェクションランス3は、内部に鉛直方向に延びる内孔を有し、鉛直方向の下端側の外周面に内孔に連通し、インジェクションランス3の径方向に互いに対向する2つの吐出口を有する。さらに、インジェクションランス3は、不図示の精錬剤供給装置から搬送ガス6と石灰源である精錬剤7とが、内孔の上端側から供給される。脱燐処理を行う際、インジェクションランス3は、図1に示すように、溶銑2の浴面下に下端側が浸漬した状態で、精錬剤供給装置から供給される搬送ガス6と精錬剤7とを2つの吐出口から溶銑2に吹き込む。
精錬剤7は、CaOを主体とする石灰系の精錬剤であって、CaOを60%以上含み、Ig-loss値が4.0質量%以上35.0質量%以下である。また、精錬剤7は、粒径が2mm以下であることが好ましい。精錬剤7の粒径を2mm以下とすることで、精錬剤7の溶融(滓化)速度が向上する。溶銑2に吹き込まれた精錬剤7は、溶銑2中を浮上しながら溶銑2の熱で溶融(滓化)し、溶銑2の浴面に浮上するスラグ8を形成する。
上吹きランス4は、溶銑保持容器1の上方に配されるランスであり、下端に設けられた2つのノズルから気体や粉体を噴射する。本実施形態では、上吹きランス4には、気体酸素源9を供給する経路、及び搬送ガス10と脱燐剤11とを供給する経路の2系統の異なる経路が形成される。この2系統の経路の上吹きランス4の上端側は、気体酸素源9の供給装置(不図示)、並びに搬送ガス10及び脱燐剤11の供給装置(不図示)にそれぞれ接続される。これらの供給装置から供給される、気体酸素源9及び脱燐剤11を含む搬送ガス10は、上吹きランス4の下端に設けられた2つのノズルから、鉛直方向下方の溶銑2の浴面に向かってそれぞれ噴射される。
上吹きランス4から噴射される脱燐剤11は、酸化鉄源を含む固体酸素源であり、鉄鉱石、ミルスケール、砂鉄、集塵ダスト(高炉や転炉、焼結工程等において排出ガスから回収される鉄分含有ダスト)などが用いられる。脱燐剤11は、粒径が1mm以下の微粉状であることが好ましく、発生形態として粒径1mm以下の砂鉄または微粉状の鉄鉱石であることが、粉砕処理の必要がないことからより好ましい。さらに、砂鉄は、固体酸素源として機能するのみならず、酸化チタンを7質量%~10質量%程度含有していることからCaOを主体とする精錬剤7の滓化促進剤としての機能も備えており、特に好適である。
次いで、インジェクションランス3からの溶銑2への搬送ガス6及び精錬剤7の吹込み、上吹きランス4からの気体酸素源9、搬送ガス10及び脱燐剤11の噴射、並びに投入シュート5からの脱燐剤11の添加が行われる(脱燐処理)。脱燐処理では、溶銑保持容器1を反応容器として、CaOを主体とする石灰源である精錬剤7と、気体酸素源9及び脱燐剤11,12である固体酸素源とを溶銑2に添加することで脱燐反応を行う。この際、精錬剤7は、滓化し、溶銑2の浴面上に浮上するスラグ8を形成する。また、酸素源は、溶銑2中の燐を酸化することで燐酸化物を生成する。生成された燐酸化物は、スラグ8に取り込まれることで、溶銑2から燐が除去される。
CaCO3 → CaO +CO2 ・・・(5)
Ca(OH)2 → CaO +H2O ・・・(6)
精錬剤7の添加量は、溶銑2の脱燐処理前の溶銑2の成分や、目標とする脱燐処理後の溶銑2の成分、溶銑2の量等に応じて適宜決定される。
以上で、特定の実施形態を参照して本発明を説明したが、これら説明によって発明を限定することを意図するものではない。本発明の説明を参照することにより、当業者には、開示された実施形態の種々の変形例とともに本発明の別の実施形態も明らかである。従って、特許請求の範囲は、本発明の範囲及び要旨に含まれるこれらの変形例または実施形態も網羅すると解すべきである。
例えば、上記実施形態では、溶銑保持容器1は溶銑鍋としたが、本発明はかかる例に限定されない。溶銑保持容器1は、溶銑2を収容可能で、上記と同様な脱燐処理設備にて処理可能なものであればよく、例えば、溶銑搬送容器であるトピードカー等の容器であってもよい。
また、固体酸素源は、上吹きランス4のみから投入されてもよく、投入シュート5のみから添加されてもよい。なお、スラグ8の酸素ポテンシャルの向上と火点の冷却による脱燐促進効果が得られることから、固体酸素源は、上吹きランス4から搬送ガス10と共に添加(投射)されることが好ましい。また、投入シュート5のみから固体酸素源を添加する場合には、上吹きランス4から投入する場合と同様な理由から、固体酸素源は、溶銑2の浴面の火点近傍に添加されることが好ましい。
(1)本発明に一態様に係る溶銑2の脱燐方法は、溶銑保持容器1に収容された溶銑2に、石灰源となる精錬剤7と酸素源(脱燐剤11,12や気体酸素源9)とを添加することで溶銑2を脱燐処理する際に、精錬剤7として、Ig-loss値が4.0質量%以上35.0質量%以下であり、生石灰を60質量%以上含むものを用いる。
上記(1)の構成によれば、反応性に優れた石灰系の精錬剤7を用いて脱燐処理をする際に、H2OガスやCO2ガスが適度に発生し、滓化が促進されるために、脱燐反応が促進される。このため、高い脱燐効率が得られ、使用する精錬剤7の使用量を低減することができることから、処理に伴って発生するダストの低減や、処理コストの低廉化、スラグの発生量の低減といった優れた効果を奏する。また、H2OガスやCO2ガスの発生によって、スラグ8のフォーミングが抑制され、脱燐処理中のスラグ8の噴出が抑えられるため、生産性を高めることができる。さらに、精錬剤7のIg-loss値を調整するだけでよいため、既存の設備においても容易に導入することできる。さらに、CaF2系の媒溶剤を用いなくとも滓化が促進されるため、脱燐処理効率を高めることができる。
上記(2)の構成によれば、インジェクションランス3から溶銑2に精錬剤7を吹き込む際に、攪拌条件が適正化され、十分な攪拌性で攪拌されることから、脱燐効率をより向上させることができる。
上記(3)の構成によれば、溶銑2と精錬剤7との濡れ性が改善されるため、脱燐効率をより向上させることができる。
(4)上記(1)~(3)のいずれかの構成において、石灰源として、精錬剤7のみを用いる。
上記(4)の構成によれば、反応性が高く、滓化性に優れた精錬剤7のみを石灰源として用いることで、脱燐効率をより向上させることができる。
(5)本発明の一態様に係る精錬剤は、Ig-loss値が4.0質量%以上35.0質量%以下であり、生石灰を60質量%以上含み、溶銑の脱燐処理に用いられる。
上記(5)の構成によれば、上記(1)の構成と同様な効果を得ることができる。
実施例1では、まず、高炉から出銑され、高炉鋳床で脱珪処理された溶銑2を、溶銑保持容器1である250トン容量の溶銑鍋に移注し、図1に示す脱燐処理設備まで搬送した。次いで、脱燐処理設備では、インジェクションランス3からの精錬剤石灰源の吹込み、上吹きランス4からの気体酸素源9及び脱燐剤11の噴射、並びに投入シュート5からの脱燐剤12の添加を行うことで、脱燐処理を行った。なお、脱燐処理前の、溶銑2のシリコン濃度は0.15質量%、炭素濃度は4.5質量%、燐濃度は0.121質量%~0.125質量%であった。
表1に、実施例1における攪拌動力及び精錬剤の条件、並びに調査結果となる処理前後での溶銑2中の燐濃度及び脱燐率(脱燐処理の前後で溶銑2中の燐が除去された割合)を示す。表1に示すように、いずれの条件においても脱燐率は60%以上と高くなることが確認された。
実施例2では、実施例1-11と同様な条件について、攪拌動力(εg+εP)を265W/t以上1392W/t以下に変化させてそれぞれ脱燐処理を行った。なお、溶銑2の脱燐処理前の燐濃度は、0.121質量%~0.125質量%であった。それ以外の条件については、実施例1-14と同じである。
表2に示すように、いずれの条件においても脱燐率は76%以上と高いものの、撹拌動力(εg+εP)を300W/t以上1000W/t以下の範囲とすることで脱燐率がさらに向上することが確認できた。
実施例3では、実施例2-3と同様な条件について、精錬剤7の比表面積を0.41m2/g~5.13m2/gに変化させてそれぞれ脱燐処理を行った。なお、溶銑2の脱燐処理前の燐濃度は、0.121質量%~0.125質量%であった。それ以外の条件については、実施例2-3と同じである。
表3に示すように、いずれの条件においても脱燐率は80%以上と高くなり、さらに比表面積を0.5m2/g以上5m2/gの範囲とすることで脱燐率がより向上することが確認できた。
実施例4では、実施例3-5と同様な条件について、攪拌動力を457W/tまたは726W/tとし、石灰源中の精錬剤7の比率を50%~100%に変化させてそれぞれ脱燐処理を行った。なお、溶銑2の脱燐処理前の燐濃度は、0.124質量%~0.126質量%であった。それ以外の条件については、実施例3-5と同じである。
表4に示すように、いずれの条件においても脱燐率は85%以上と高くなり、いずれの攪拌動力の条件においても、インジェクションランス3から吹き込む石灰源中の精錬剤7の比率の増加に伴って脱燐率がさらに向上することが確認できた。
2 溶銑
3 インジェクションランス
4 上吹きランス
5 投入シュート
6 搬送ガス
7 精錬剤
8 スラグ
9 気体酸素源
10 搬送ガス
11,12 脱燐剤(固体酸素源)
Claims (5)
- 溶銑保持容器に収容された溶銑に、石灰源となる精錬剤と酸素源とを添加することで前記溶銑を脱燐処理する際に、
前記精錬剤として、Ig-loss値が4.0質量%以上35.0質量%以下であり、生石灰を60質量%以上含むものを用いることを特徴とする溶銑の脱燐方法。 - 前記精錬剤の比表面積を、0.5m2/g以上5m2/g以下とすることを特徴とする請求項1または2に記載の溶銑の脱燐方法。
- 前記石灰源として、前記精錬剤のみを用いることを特徴とする請求項1~3のいずれか1項に記載の溶銑の脱燐方法。
- Ig-loss値が4.0質量%以上35.0質量%以下であり、生石灰を60質量%以上含み、溶銑の脱燐処理に用いられる精錬剤。
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US16/473,876 US11542566B2 (en) | 2016-12-27 | 2017-12-15 | Method for dephosphorization of hot metal, and refining agent |
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EP17887903.7A EP3564396B1 (en) | 2016-12-27 | 2017-12-15 | Method for dephosphorization of molten iron, and refining agent |
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KR102331435B1 (ko) | 2021-11-25 |
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