JP5707702B2 - Hot metal dephosphorization method - Google Patents

Description

  The present invention relates to a hot metal dephosphorization treatment method using a CaO-based medium solvent as a dephosphorization medium solvent and blowing an oxygen-containing gas from the top blowing lance toward the hot metal bath surface, and used at that time Refining top blow lance.

In recent years, dephosphorization treatment (also referred to as “preliminary dephosphorization treatment”) is carried out in advance in the hot metal stage, and after removing a certain amount of phosphorus in the hot metal, this hot metal is charged into a converter and decarburization refining is carried out. However, steelmaking methods for melting molten steel from hot metal have been developed. In this case, the hot metal dephosphorization process uses equipment such as a torpedo car, hot metal ladle, converter, etc., and the hot metal contained in these equipment contains an oxygen source such as oxygen gas and solid iron oxide, and a dephosphorization solvent. The CaO-based solvent is added, the phosphorus in the hot metal is oxidized with an oxygen source, and the resulting phosphor oxide (P ₂ O ₅ ) is taken into the slag formed by the CaO-based solvent. ing.

In this dephosphorization treatment, in order to efficiently transfer phosphorus in the hot metal from hot metal to slag with a small amount of CaO-based solvent, it is extremely important to rapidly melt and hatch the CaO-based solvent. However, from the viewpoint of thermodynamics, phosphorus in the hot metal is more easily oxidized and removed as the temperature is lower. Therefore, the dephosphorization treatment is generally performed at a relatively low temperature of 1300 to 1400 ° C. That is, this temperature condition is not a suitable condition for the hatching of the CaO-based solvent. Therefore, in order to hatch the CaO-based solvent in a relatively low temperature range of 1300 to 1400 ° C., conventionally, The combined use of fluorite (CaF ₂ ), which is a melting point depressant, has been widely performed.

  However, in recent years, elution of fluorine (F) from slag has become a problem from the viewpoint of environmental protection. For this reason, dephosphorization that can be efficiently dephosphorized without using a fluorine source such as fluorite. The development of phosphorus technology was desired. In order to meet this demand, several methods for dephosphorization by promoting the hatching of the CaO-based solvent without using a fluorine source such as fluorite have been proposed.

For example, Patent Document 1 contains CaO powder and Al ₂ O ₃ powder of more than 20% by mass and less than 50% by mass with respect to the CaO powder in the hot metal accommodated in the top-bottom blown converter. A method is disclosed in which the mixed powder is sprayed from an upper blowing lance using oxygen gas as a carrier gas, and a dephosphorization process is performed while stirring the molten metal by blowing a stirring gas from the bottom of the furnace. However, in the method of Patent Document 1, although the melting point of CaO is lowered by Al ₂ O ₃ to be added and the hatching of CaO can be promoted, the concentration of Al ₂ O ₃ in the slag is increased. There is a concern that the refractory will be worn out and the cost will increase. Moreover, since the Al ₂ O ₃ concentration in the slag is increased, there is a problem that the dephosphorization rate is decreased.

In Patent Document 2, when the basicity of the slag is 1.1 or less with respect to the hot metal contained in the converter type reaction vessel, massive quick lime having a particle size of 20 mm or less is added, and When the basicity of the slag exceeds 1.1, CaO powder having a particle size of 100 mesh (149 μm) or less, preferably 200 mesh (74 μm) or less is sprayed with oxygen gas from the top blowing lance to remove hot metal. A method of phosphorus treatment is disclosed. Here, the basicity of slag is the mass ratio (CaO / SiO ₂ ) between CaO and SiO ₂ in the slag.

  Generally, in the dephosphorization reaction, a high basicity slag is formed to reduce the phosphorus concentration in the hot metal to a required level, and the basicity of the slag in the dephosphorization process is generally over 1.1. . In Patent Document 2, when the basicity exceeds 1.1, quick lime of 100 mesh or less is used. Therefore, most of the quick lime needs to be 100 mesh or less, and the quick lime is reduced to such a size. It takes a great deal of cost to granulate, and Patent Document 2 is not an industrially feasible method.

Patent Document 3 discloses a granular dephosphorization solvent mainly composed of CaO, SiO ₂ and iron oxide from a central hole at the tip of the top blowing lance, together with a burner flame using an oxygen-containing gas as a carrier gas. There has been disclosed a dephosphorization method in which an oxygen-containing gas is sprayed from a peripheral hole outside the center hole and simultaneously added to a hot metal bath surface in a converter reactor. Moreover, in patent document 3, the central hole for injecting a granular dephosphorization medium solvent is a Laval nozzle which becomes a supersonic jet, and oxygen gas for burning the fuel of a burner is supplied from a central hole. It is described. However, in the method of Patent Document 3, since dust containing metallic iron is blown from the central hole as the iron oxide together with the oxygen-containing gas, there is a risk of ignition by metallic iron in the transport path, which is not realistic. In addition, the mixing of the oxygen gas supplied from the center hole and the fuel gas supplied from the periphery thereof is insufficient, the combustion efficiency is poor, and furthermore, the discharge rate of the dephosphorization medium solvent is high, so the burner The time spent in the flame is short, and there is a risk that it will not heat or melt sufficiently.

JP 2000-345226 A JP 2000-73112 A JP 2007-92158 A

  As described above, when the hot metal is dephosphorized using a CaO-based solvent as a main dephosphorizing medium solvent, the dephosphorization process technology can efficiently dephosphorize without using a fluorine source such as fluorite. However, the conventional dephosphorization processing method is difficult to be industrially satisfactory in terms of cost, and the manufacturing cost has been inevitably increased.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to quickly hatch a CaO-based solvent without using a fluorine source such as fluorite, and to efficiently produce hot metal. Another object is to provide a dephosphorization method that can be dephosphorized at low cost, and to provide an upper blowing lance for refining used therefor.

  The present inventors diligently studied and studied to solve the above problems. The results of the examination and research are explained below.

The hot metal dephosphorization reaction using the CaO-based solvent as the main dephosphorizing medium solvent is produced by the reaction of the CaO-based slag generated by the CaO-based solvent with the phosphorus source in the hot metal and the supplied oxygen source. It is important to determine how quickly the CaO-based medium solvent is hatched since the process proceeds by incorporating the phosphorous oxide (P ₂ O ₅ ).

  As a result of the study, the flame is surrounded by a burner so as to surround the periphery of the dephosphorization solvent discharged from the top blowing lance, which is carried by an inert gas, before the dephosphorization medium comes into contact with the hot metal. It was found that the formation of the band is the optimum condition for promoting the mixing / contact of the hot metal and the dephosphorization medium solvent and for rapid incubation of the dephosphorization medium solvent.

  For the lance structure that forms the burner, in order to simplify the lance structure as much as possible, a dephosphorizing medium solvent is supplied from the central hole of the lance shaft center together with an inert gas as a conveying gas, and the periphery of this central hole is In addition, an annular fuel supply nozzle and an oxygen-containing gas supply nozzle are provided in this order from the axial center side, respectively supplying fuel and oxygen-containing gas, and burning the fuel with the oxygen-containing gas to form a flame, thereby dephosphorization. The method of heating and melting the solvent was used. In this case, the oxygen gas in the oxygen-containing gas supplied from the oxygen-containing gas supply nozzle is consumed for the combustion of the fuel, so that it hardly contributes to the oxidation of phosphorus in the hot metal. Therefore, a nozzle (= peripheral hole) for supplying a refining oxygen-containing gas for oxidizing phosphorus in the hot metal is provided on the outer periphery of the oxygen-containing gas supply nozzle.

  It is also effective for the dephosphorization reaction to eject the dephosphorization medium solvent from the center hole using the oxygen-containing gas as a carrier gas. However, when converter dust or the like is used as part of the dephosphorization medium solvent, May contain metallic iron, and there is a danger that it reacts with oxygen gas and ignites inside the lance, making it difficult to put it to practical use industrially.

  In addition, when oxygen-containing gas is blown as a carrier gas for dephosphorization medium solvent from the center hole, and this oxygen-containing gas is used together for fuel combustion, in combustion of oxygen-containing gas and fuel from the center hole, The flame length is shortened, and the residence time when the dephosphorizing medium solvent passes through the flame zone cannot be secured sufficiently. On the other hand, by installing an oxygen-containing gas supply nozzle around the fuel supply nozzle and ejecting the oxygen-containing gas from the oxygen-containing gas supply nozzle, the combustion of the fuel is slowed down, the flame length is increased, and it is efficient It was found that the dephosphorization medium solvent can be heated and melted.

  FIG. 1 shows the measurement of the length of the flame formed when oxygen gas for combustion is supplied from both the central hole and the oxygen-containing gas supply nozzle provided around the fuel supply nozzle at different supply ratios. Results are shown. As shown in FIG. 1, it was found that the flame length increases as the oxygen gas supply ratio from the oxygen-containing gas supply nozzle increases. As a result, it has been found that the dephosphorization medium solvent can be efficiently heated and melted.

  The present invention has been made on the basis of the above examination results, and the hot metal dephosphorization processing method according to the first invention uses an inert gas as a carrier gas from a central hole arranged in the axial center portion of the top blowing lance. A dephosphorization medium solvent is ejected toward the hot metal, and at the same time, a flame encircling zone is formed around the ejection flow from the central hole and a reaction between the oxygen-containing gas and the fuel, and installed around the central hole. The oxygen-containing gas is blown toward the bath surface of the molten metal from the three or more peripheral holes.

  In the hot metal dephosphorization method according to the second invention, in the first invention, the dephosphorization medium solvent is lime, sintered ore, iron ore, sintered dust produced in a sintering step of iron ore, It is characterized by comprising one or more of converter slag and converter dust generated in the decarburization blowing process of hot metal.

  The refining top blow lance according to the third invention has a center hole for blowing the dephosphorization medium solvent into the axial center part of the tip of the lance, and has an annular shape concentric with the center hole around the center hole. A fuel supply nozzle and an annular oxygen-containing gas supply nozzle are provided in this order from the axial center side, and three or more peripheral holes for blowing a refining oxygen-containing gas are provided around the oxygen-containing gas supply nozzle. It is characterized by that.

  According to the present invention, the dephosphorization treatment is performed by spraying the powdered solvent medium for dephosphorization on the molten iron while heating and melting the burner flame formed at the tip of the top blowing lance. Even if a source is not used, the dephosphorization medium solvent can be hatched more quickly than before, the dephosphorization reaction can be promoted, and the hot metal having a low phosphorus concentration can be produced. In addition, since an inert gas is used as the transporting gas for the dephosphorization medium solvent, even if metallic iron is mixed in the dephosphorization medium solvent, combustion of the metallic iron in the transport path can be prevented in advance. it can. As a result, it becomes possible not only to reduce the dephosphorization medium solvent cost in the dephosphorization process, but also to eliminate the dephosphorization medium solvent necessary for dephosphorization in the converter decarburization refining in the next process, etc. Resource saving and energy saving are achieved and stabilization of the converter decarburization operation is achieved, resulting in industrially beneficial effects.

It is a figure which shows the measurement result of the flame length formed when oxygen gas for combustion is supplied by changing a supply ratio from both a center hole and an oxygen-containing gas supply nozzle. It is a longitudinal cross-sectional schematic diagram which shows the example of the top blowing lance of this invention. It is sectional drawing by the X-X 'arrow of FIG.

  Hereinafter, the present invention will be specifically described.

  The hot metal used in the dephosphorization treatment according to the present invention is a hot metal manufactured in a hot metal manufacturing facility such as a blast furnace, and the hot metal manufactured in a hot metal manufacturing facility is received in a hot metal transport container such as a hot metal pan or a torpedo car, This hot metal is conveyed to a preliminary dephosphorization processing facility. In order to efficiently perform the dephosphorization treatment with a small amount of the dephosphorization medium solvent, the silicon in the hot metal may be removed in advance (also referred to as “preliminary desiliconization treatment of hot metal”) before the dephosphorization treatment. When performing preliminary desiliconization treatment, it is preferable to reduce the silicon content of the hot metal to 0.1% by mass or less. As a means for lowering the silicon content of the hot metal to this range, an oxygen source such as oxygen gas or iron oxide is supplied to the manufactured hot metal, and the silicon in the hot metal is oxidized by these oxygen sources, and silicon is used as an oxide. A method of forcibly removing can be used. When the preliminary desiliconization process is performed, the generated slag is discharged before the dephosphorization process.

  The hot metal thus obtained is subjected to the dephosphorization treatment according to the present invention. The dephosphorization treatment according to the present invention can be carried out in a hot metal transfer container such as a hot metal ladle or a torpedo car. However, the free board is larger than these hot metal transfer containers, and the hot metal can be vigorously stirred and reduced. Since a dephosphorization process can be rapidly performed with the usage-amount of the dephosphorization medium solvent, it is preferable to carry out in a converter type refining vessel. Therefore, here, an example in which dephosphorization processing is performed using a converter-type refining vessel will be described.

  Here, the top blowing lance used in the present invention will be described. 2 and 3 are schematic views showing an example of an upper blowing lance according to the present invention, FIG. 2 is a longitudinal sectional view, and FIG. 3 is a sectional view taken along arrow X-X ′ in FIG. 2.

  As shown in FIGS. 2 and 3, the top blowing lance 1 is composed of a cylindrical lance body 2 and a copper lance tip 3 connected to the lower end of the lance body 2 by welding or the like. The main body 2 is configured from the outermost tube 8, the outer tube 9, the middle tube 10, the inner tube 11, the partition tube 12, and the innermost tube 13, six types of concentric steel pipes, that is, a hexagonal tube from the outside. The tip lance tip 3 has a center hole 4 disposed substantially at the axial center of the lance tip 3 and directed vertically downward, and an annular fuel supply nozzle 6 disposed on the outer periphery of the center hole 4. An annular oxygen-containing gas supply nozzle 7 disposed on the outer periphery of the fuel supply nozzle 6, and a plurality of peripheral holes 5 disposed on the outer periphery of the oxygen-containing gas supply nozzle 7 and directed in a vertically oblique downward direction Is installed. The central hole 4 is a straight nozzle, and the peripheral hole 5 is a divergent Laval nozzle.

  The center hole 4 is a nozzle for spraying a dephosphorization medium solvent, and the fuel supply nozzle 6 is a hydrocarbon gas fuel such as propane gas or natural gas, or a hydrocarbon liquid fuel such as heavy oil or kerosene. The nozzle for spraying, the oxygen-containing gas supply nozzle 7 is a nozzle for spraying oxygen-containing gas for burning these fuels, and the peripheral hole 5 is a nozzle for spraying oxygen-containing gas for refining. Here, the oxygen-containing gas refers to oxygen gas (pure oxygen), air, oxygen-enriched air, a mixed gas of oxygen gas and Ar gas, and the like. In this upper blow lance 1, four peripheral holes 5 are arranged. However, any number of the peripheral holes 5 may be used as long as there are three or more peripheral holes 5. You can decide accordingly.

  The gap between the outermost pipe 8 and the outer pipe 9 and the gap between the outer pipe 9 and the middle pipe 10 serve as a cooling water flow path for cooling the upper blowing lance 1. Cooling water supplied from a water supply joint (not shown) provided in the upper part passes through the gap between the outer tube 9 and the intermediate tube 10 to reach the site of the lance tip 3 and reverses at the site of the lance tip 3. The water is discharged from a drainage joint (not shown) provided in the upper part of the upper blowing lance 1 through a gap between the outermost pipe 8 and the outer pipe 9. In this case, the water supply / drainage path may be reversed.

  A gap between the middle pipe 10 and the inner pipe 11 serves as a supply flow path for oxygen-containing gas to the peripheral hole 5, and from an oxygen-containing gas supply joint (not shown) provided at the upper part of the upper blowing lance 1. The oxygen-containing gas supplied to the gap between the middle tube 10 and the inner tube 11 passes through the gap between the middle tube 10 and the inner tube 11 and is ejected from the peripheral hole 5 into the converter.

  A gap between the inner pipe 11 and the partition pipe 12 serves as a supply flow path for oxygen-containing gas to the oxygen-containing gas supply nozzle 7, and an oxygen-containing gas supply joint (not shown) provided on the upper portion of the upper blowing lance 1. The oxygen-containing gas supplied to the gap between the inner tube 11 and the partition tube 12 passes through the gap between the inner tube 11 and the partition tube 12 and is jetted from the oxygen-containing gas supply nozzle 7 into the converter. .

  A gap between the partition pipe 12 and the innermost pipe 13 serves as a fuel supply passage to the fuel supply nozzle 6, and is partitioned from a fuel supply joint (not shown) provided at the upper portion of the upper blow lance 1. The fuel supplied to the gap between the pipe 12 and the innermost pipe 13 passes through the gap between the partition pipe 12 and the innermost pipe 13 and is jetted from the fuel supply nozzle 6 into the converter.

  Further, the inside of the innermost pipe 13 is a supply flow path for a dephosphorization medium solvent to the center hole 4 using an inert gas as a carrier gas, and is provided at the upper end of the upper blowing lance 1. The dephosphorization medium solvent supplied together with the inert gas into the innermost pipe 13 from the dephosphorization medium solvent supply joint (not shown) passes through the innermost pipe 13 and is injected from the center hole 4. The Nitrogen gas, Ar gas, or the like is used as the inert gas used as the carrier gas.

  The dephosphorization according to the present invention is performed as follows with respect to the hot metal contained in a converter-type smelting vessel (hereinafter also simply referred to as “converter”) using the top blowing lance 1 having such a configuration. Perform the process.

First, a granular material of a dephosphorization medium solvent mainly composed of CaO, SiO ₂ and iron oxide is prepared, and the dephosphorization medium solvent is provided in a supply path connected to a dephosphorization medium solvent supply joint. In addition, it is charged in advance in a dispenser (not shown) for containing the dephosphorization medium solvent for the granular material. In this state, hot metal is charged into the converter. The hot metal used can be treated with any composition, and may be subjected to preliminary desulfurization treatment or preliminary desiliconization treatment before dephosphorization treatment. Incidentally, the main chemical components of the hot metal before the dephosphorization treatment are: carbon: 3.8 to 5.0% by mass, silicon: 0.2% by mass or less, sulfur: 0.05% by mass or less, phosphorus: 0.08 It is about -0.2 mass%. Moreover, if the hot metal temperature is in the range of 1200 to 1350 ° C., dephosphorization can be performed without any problem.

  Next, a dephosphorizing medium solvent is sprayed from the center hole 4 of the top lance 1 toward the bath surface of the hot metal in the converter using an inert gas as a carrier gas. Simultaneously with the spraying of the dephosphorization medium solvent, the hydrocarbon-based fuel is supplied from the fuel supply nozzle 6 of the top blowing lance 1, the oxygen-containing gas is supplied from the oxygen-containing gas supply nozzle 7, and supplied from the fuel supply nozzle 6. The fuel to be burned is burned by the oxygen-containing gas supplied from the oxygen-containing gas supply nozzle 7 to form a flame at the tip of the top blowing lance 1. The dephosphorization medium solvent supplied from the center hole 4 is heated and melted by the heat of the flame envelopment formed, and is sprayed onto the hot metal bath surface in a molten state. At that time, oxygen-containing gas for dephosphorization refining is blown from the peripheral hole 5 of the top blowing lance 1 toward the bath surface of the hot metal, and from a bottom blowing tuyere (not shown) arranged at the bottom of the converter furnace. A non-oxidizing gas such as nitrogen gas or a rare gas such as Ar gas is blown into the hot metal as a stirring gas to stir the hot metal.

The dephosphorization medium solvent sprayed on the hot metal bath surface immediately hatches to form slag, and the supplied oxygen-containing gas for dephosphorization and phosphorus in the hot metal react to form P ₂ O _5. It is formed. Combined with strong stirring of the hot metal and slag by the stirring gas, the formed P ₂ O ₅ is rapidly absorbed into the slag, and the dephosphorization reaction of the hot metal proceeds promptly.

Moreover, from the viewpoint of suppressing the preparation cost of the dephosphorization medium solvent, as a raw material of the dephosphorization medium solvent, converter slag (CaO-SiO ₂ slag) generated in the hot metal decarburization blowing process, converter dust ( Iron oxide (also called “OG dust”) or sintered dust (mixture of CaO and iron oxide) produced in the iron ore sintering process, and quick lime, sintered ore, iron ore, etc. added to these Thus, it is preferable to prepare a desired composition. An Al ₂ O ₃ source may be intentionally mixed with the dephosphorization medium solvent as a melting point depressant for CaO. However, in the present invention, sufficient hatchability can be ensured by heating and melting with a burner. _It is not necessary to mix the ₂ O ₃ source. Similarly, a fluorine compound such as fluorite which is a melting point depressant for CaO is not required. In particular, it is preferable not to use a fluorine compound such as fluorite as a dephosphorization medium solvent from the viewpoint of protecting the environment by suppressing the amount of fluorine eluted from the slag when recycling the slag. However, a substance in which fluorine is inevitably mixed as an impurity component may be used. The composition of the dephosphorization for medium solvent, CaO 50 to 70 wt%, SiO ₂ 10 to 30% by weight, FeO may be 10 to 25 mass%.

  If the oxygen source at the time of dephosphorization is only a gaseous oxygen-containing gas, the hot metal temperature will rise too much and the dephosphorization reaction may be inhibited, so if necessary, a solid oxygen source such as mill scale or iron ore, or Iron scrap may be added. These addition amounts can be appropriately changed according to the silicon concentration, phosphorus concentration, carbon concentration and the like in the hot metal. Further, the amount of the dephosphorization medium solvent to be added is changed according to the silicon concentration and the phosphorus concentration in the hot metal, but it is sufficient if it is about 40 kg per ton of hot metal.

  As described above, according to the present invention, the dephosphorization medium solvent is supplied from the center hole 4 of the top blowing lance 1 together with the inert gas of the carrier gas, and the fuel supply nozzle 6 disposed around the center hole 4. A hydrocarbon-based fuel is supplied from an oxygen-containing gas, and an oxygen-containing gas is supplied from an oxygen-containing gas supply nozzle 7 disposed around the fuel supply nozzle 6 to form a flame. The flame is used to heat and melt the dephosphorization medium solvent. As a result, the solvent for dephosphorization can be rapidly hatched, the dephosphorization reaction can be promoted more quickly than before, and it is possible to produce hot metal having a low phosphorus concentration. It becomes. In addition, since an inert gas is used as the carrier gas for the dephosphorization medium solvent, it is possible to prevent the combustion of the metal iron in the supply path even if metal iron is mixed in the dephosphorization medium solvent. it can.

  Preliminary desiliconization treatment was applied to the hot metal produced in the blast furnace, and the slag after the preliminary desiliconization treatment was discharged, and then the hot metal was charged into a 5 ton small converter refining test facility and the conditions were changed. Thus, a dephosphorization test was conducted.

The dephosphorization process is performed by refining from the peripheral hole of the top blowing lance while stirring the hot metal by blowing nitrogen gas from the bottom blowing tuyeres at the bottom of the furnace at a supply rate of 0.05 to 0.15 Nm ³ / (min · t). While oxygen gas is blown as the oxygen-containing gas for use, propane gas is supplied from the fuel supply nozzle while blowing nitrogen gas from the center hole of the upper blowing lance as the carrier gas, and oxygen-containing gas supply nozzle Oxygen gas was supplied from The top blowing lance used is the same as the top blowing lance shown in FIG.

Spraying rate of dephosphorization for medium solvent was constant of 5 kg / min, the flow rate of the refining oxygen gas was constant of 420Nm ³ / hr, the flow rate of propane gas was constant 20 Nm ³ / hr. The hot metal temperature was adjusted to 1200 to 1300 ° C. before the treatment, and the post-treatment temperature was adjusted to 1340 to 1360 ° C.

  For comparison, tests (Comparative Example 1 and Comparative Example 2) in which a burner was not formed at the tip of the lance were also conducted. In addition, a test (Comparative Example 3) was conducted in which oxygen gas was used as the carrier gas for the dephosphorization medium solvent, and propane gas was burned with this oxygen gas. Table 1 shows treatment conditions and test results in the dephosphorization treatment of each test.

  As shown in Table 1, in Invention Examples 1 to 3, compared with Comparative Examples 1 to 3, the basic unit of the dephosphorization medium solvent and the basic unit of the refining oxygen gas were substantially the same, but the low phosphorus concentration The hot metal could be dephosphorized to the level. Thus, it was confirmed that hot metal having a low phosphorus concentration can be produced inexpensively and stably by the present invention without using a fluorine source such as fluorite.

DESCRIPTION OF SYMBOLS 1 Top blow lance 2 Lance main body 3 Lance tip 4 Center hole 5 Peripheral hole 6 Fuel supply nozzle 7 Oxygen-containing gas supply nozzle 8 Outer tube 9 Outer tube 10 Middle tube 11 Inner tube 12 Partition tube 13 Inner tube

Claims (2)

The dephosphorization medium solvent in the case of containing metallic iron is contained in the dephosphorization medium solvent from the center hole arranged in the axial center portion of the top blowing lance, using an inert gas as a carrier gas. Without igniting the metal iron in the transport path, the metal iron is ejected toward the hot metal, and at the same time, the oxygen-containing gas and the fuel are supplied from the oxygen-containing gas supply nozzle and the fuel supply nozzle installed around the center hole, respectively, Around the jet flow from the center hole, a flame envelopment zone is formed by the reaction between the oxygen-containing gas and the fuel, and there are three or more holes installed around the oxygen-containing gas supply nozzle and the fuel supply nozzle. A method for dephosphorizing hot metal, characterized in that an oxygen-containing gas is sprayed from a hole toward a bath surface of the hot metal. The dephosphorization solvent is lime, sintered ore, iron ore, sintered dust produced in the iron ore sintering process, converter slag produced in the hot metal decarburization blowing process, converter dust The hot metal dephosphorization method according to claim 1, wherein the hot metal dephosphorization method comprises any one kind or two kinds or more.

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