WO2015105035A1 - Procédé pour empêcher la resulfuration d'une fonte brute à l'état liquide après traitement de désulfuration - Google Patents

Procédé pour empêcher la resulfuration d'une fonte brute à l'état liquide après traitement de désulfuration Download PDF

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Publication number
WO2015105035A1
WO2015105035A1 PCT/JP2015/000001 JP2015000001W WO2015105035A1 WO 2015105035 A1 WO2015105035 A1 WO 2015105035A1 JP 2015000001 W JP2015000001 W JP 2015000001W WO 2015105035 A1 WO2015105035 A1 WO 2015105035A1
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Prior art keywords
desulfurization
impeller
hot metal
processing vessel
slag
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PCT/JP2015/000001
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English (en)
Japanese (ja)
Inventor
中井　由枝
内田　祐一
菊池　直樹
市川　彰
鈴木　紀彦
祐樹 鍋島
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Ｊｆｅスチール株式会社
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Application filed by Ｊｆｅスチール株式会社 filed Critical Ｊｆｅスチール株式会社
Priority to KR1020167021363A priority Critical patent/KR101840962B1/ko
Priority to JP2015556780A priority patent/JP6052436B2/ja
Priority to CN201580004067.5A priority patent/CN105899689B/zh
Priority to BR112015009665A priority patent/BR112015009665A2/pt
Publication of WO2015105035A1 publication Critical patent/WO2015105035A1/fr

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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
    • C21C1/00—Refining of pig-iron; Cast iron
    • C21C1/06—Constructional features of mixers for pig-iron
    • 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
    • F27D27/00—Stirring devices for molten 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
    • C21C2300/00—Process aspects
    • C21C2300/08—Particular sequence of the process steps
    • 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
    • F27D19/00—Arrangements of controlling devices
    • F27D2019/0028—Regulation
    • F27D2019/0071—Regulation using position sensors
    • 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
    • F27D27/00—Stirring devices for molten material
    • F27D2027/002—Gas stirring
    • 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
    • F27D99/00—Subject matter not provided for in other groups of this subclass
    • F27D2099/0083—Drives; Auxiliary drives

Definitions

  • the present invention is generated at the time of desulfurization treatment of molten iron and suspended in the molten iron after desulfurization treatment (
  • the present invention relates to a method for preventing re-sulfurization caused by desulfurization slag remaining in a processing vessel.
  • desulfurization is performed at the hot metal stage.
  • the desulfurization slag having a high sulfur content generated by the desulfurization treatment is discharged from the treatment vessel, and thereafter, the hot metal in the treatment vessel is subjected to the dephosphorization treatment and decarburization refining in the next step.
  • the desulfurized slag is discharged from the processing vessel, but the fine desulfurized slag suspended in the hot metal is carried over to the next process.
  • the desulfurization slag adhering to the side wall of the processing vessel may be carried over to the next process.
  • desulfurization treatment is reductive refining
  • the dephosphorization treatment and decarburization refining in the next step are oxidation refining, so the sulfur contained in the desulfurization slag carried over to the next step is oxidized to hot metal or molten steel. Return to. As a result, the sulfur concentration of the hot metal or molten steel increases. This phenomenon is referred to as “resulfurization”.
  • the hot metal desulfurization treatment includes a method of injecting a CaO-based desulfurizing agent (lime-based desulfurization-flux) into the hot metal, a method of stirring and mixing the CaO-based desulfurizing agent and hot metal using a mechanical stirring desulfurization apparatus, Or the method of injecting a metal Mg type
  • a CaO-based desulfurizing agent lime-based desulfurization-flux
  • the desulfurizing agent in order to improve the reaction efficiency of the desulfurizing agent, the desulfurizing agent is dispersed in the hot metal by injection or mechanical stirring. When the desulfurization agent is well dispersed, the desulfurization reaction is performed efficiently. However, the better the dispersion state of the desulfurizing agent, the finer the desulfurizing agent is suspended in the hot metal, and the smaller the particle size of the dispersed desulfurizing agent, the more difficult it is to float from the hot metal. If the hot metal is allowed to stand for a long time after the desulfurization treatment, the fine desulfurization agent suspended in the hot metal can float on the hot metal bath surface and be removed from the processing vessel. However, such a treatment is not performed in a process because standing for a long time causes a decrease in productivity and a decrease in hot metal temperature.
  • Patent Document 1 uses a desulfurizing agent in which 10 to 20% by mass of Al 2 O 3 is added to 80 to 90% by mass of a Mg—CaO—CaF 2 mixture, and this desulfurizing agent is injected into the hot metal together with a carrier gas.
  • this desulfurizing agent is injected into the hot metal together with a carrier gas.
  • Patent Document 2 a desulfurizing agent is blown into the hot metal through an injection lance, and a stirring gas is blown from a lance immersed to a depth of 1 m or less from the hot metal bath surface so that the vicinity of the interface between the slag and hot metal is observed. It has been proposed to desulfurize the hot metal with strong stirring.
  • Patent Document 1 is a technique for preventing desulfurization by forming a desulfurization slag that can be easily removed by using the desulfurization agent.
  • the purpose is to promote the reaction between hot metal and hot metal by stirring.
  • the blowing of the stirring gas in Patent Document 2 is intended to stir the desulfurizing agent and hot metal floating on the hot metal. That is, neither of Patent Documents 1 and 2 is intended to promote the floating and separation of fine desulfurized slag suspended in hot metal.
  • Patent Documents 1 and 2 when an agitation gas injection lance is required and the desulfurization process is performed using a general mechanical agitation desulfurization apparatus that is performed without using the agitation gas, There is also a problem that a new agitation gas injection lance is required.
  • Patent Document 3 proposes a method for desulfurization treatment by blowing carbonaceous material together with the transfer gas from the bottom surface of the impeller rotating shaft without installing an injection lance.
  • Patent Document 3 aims to promote the desulfurization reaction by blowing the desulfurizing agent into a region where the stirring turbulent energy density is high.
  • the blowing of the carbonaceous material in patent document 4 aims at promoting the melt
  • Patent Document 3 and Patent Document 4 the floating and separation of the fine desulfurization agent suspended in the hot metal does not occur.
  • neither Patent Documents 3 and 4 are intended to promote the floating and separation of the fine desulfurization agent suspended in the hot metal after the desulfurization treatment.
  • JP-A-8-269519 JP-A-4-235210 JP 52-85013 A Japanese Patent Laid-Open No. 2005-200762
  • the present invention has been made in view of the above circumstances, and the object of the present invention is to form a molten steel from molten iron by performing decarburization refining in the next step on the molten iron subjected to desulfurization treatment. It is intended to provide a method for preventing resulfurization caused by fine desulfurization slag generated during the desulfurization treatment and suspended in the hot metal and / or desulfurization slag adhering to the side wall of the treatment vessel.
  • the gist of the present invention for solving the above problems is as follows.
  • a desulfurization process is performed on the hot metal in the processing vessel using a mechanical stirring desulfurization apparatus, and then an inert gas is blown into the hot metal from a gas ejection hole installed in an impeller of the mechanical stirring desulfurization apparatus.
  • the hot metal is stirred and desulfurized slag suspended in the hot metal and / or desulfurized slag adhering to the inner wall of the processing vessel is levitated on the hot metal bath surface, and the levitated desulfurized slag is discharged from the processing vessel and then treated.
  • a method of preventing hot metal from being desulfurized after desulfurization in which the hot metal in the container is conveyed to the next step.
  • a vortex center formed by rotating the impeller while rotating the impeller in a state in which the portion of the gas ejection hole is immersed in the hot metal and rotating the impeller immersed in the hot metal from the surface of the hot metal in the processing vessel The position of the impeller and / or the rotation speed of the impeller is adjusted so that the distance between the recesses is smaller than the distance from the stationary hot water surface to the upper end of the impeller. How to prevent hot metal from being sulphided.
  • H is the distance (m) from the hot water surface to the recess at the center of the vortex
  • N is the number of revolutions of the impeller (times / min)
  • D is the inner diameter (m) of the processing vessel.
  • ⁇ is the impeller blade inclination angle (rad)
  • b is the impeller height (m)
  • d is the impeller rotational diameter (m)
  • n P is the number of impeller blades
  • g is the gravitational acceleration.
  • Re is the number of ray nozzles (dimensionless)
  • ⁇ is the density of molten metal (kg / m 3 )
  • ⁇ is the viscosity (Pa ⁇ s) of the molten metal.
  • the desulfurized slag remaining in the processing vessel is forcibly levitated by stirring with an inert gas ejected from a gas ejection hole installed in the impeller, and the desulfurized slag that has been levitated is discharged from the processing vessel, Thereafter, the hot metal is subjected to the dephosphorization treatment and decarburization refining in the next step.
  • the hot metal is subjected to the dephosphorization treatment and decarburization refining in the next step.
  • FIG. 1 is a schematic view showing an example in which a desulfurization slag flotation / separation step is performed.
  • FIG. 2 is a schematic diagram when a vortex is formed by stirring with an impeller in a mechanical stirring type desulfurization apparatus.
  • the CaO-based desulfurizing agent and the hot metal are stirred in the processing vessel in order to increase the reaction interface area, and the CaO-based desulfurizing agent is dispersed in the hot metal.
  • the CaO-based desulfurization agent any known one can be used without any problem.
  • quick lime (CaO) limestone (CaCO 3 ), slaked lime (Ca (OH) 2 ), dolomite (CaO—MgO), and so on.
  • stone CaF 2) or alumina (Al 2 O 3)
  • CaO slag formation accelerators such as (fluxing agent for CaO) that is mixed for about 5 to 30% by weight and the like are used.
  • the sulfur in the hot metal reacts with the CaO-based desulfurizing agent dispersed in the hot metal along the reaction formula of “CaO + S ⁇ CaS + O”, and desulfurized slag containing CaS and having a high sulfur concentration is generated.
  • the desulfurization slag floats on the hot metal bath surface at the end of the desulfurization process, and the hot metal bath surface is covered with the desulfurization slag.
  • This desulfurization slag is discharged from the processing container by a slag scraper after the desulfurization process (referred to as “desulfurization slag draining process”). After this desulfurization slag discharge process, the hot metal in the processing vessel is conveyed to the next dephosphorization process and decarburization refining process.
  • the ascending speed of the desulfurized slag in the hot metal is proportional to the particle size of the desulfurized slag according to Stokes' law. Therefore, the ascending speed of the fine desulfurization slag suspended in the hot metal is slow, and the desulfurization process is completed while the fine desulfurization slag is suspended in the hot metal.
  • the desulfurization slag adhering to the inner wall of the processing vessel hardly floats, and most of the desulfurization slag adhering to the inner wall of the processing vessel remains as it is at the end of the desulfurization treatment. Most of the fine desulfurization slag suspended in the hot metal and the desulfurization slag adhering to the inner wall of the processing container remain in the processing container without being discharged from the processing container in the desulfurization slag discharging process.
  • the next dephosphorization process and decarburization refining are oxidation refining. Therefore, if desulfurized slag that is not discharged in the desulfurization slag discharge process and remains in the processing vessel is carried over to the next dephosphorization treatment process or decarburization refining process, CaS in the desulfurization slag is oxidized and CaO is oxidized. Generate. Sulfur (S) dissociated from CaS due to the oxidation of CaS is transferred to hot metal or molten steel, and resulfurization occurs in which the sulfur concentration of the molten iron or molten steel increases.
  • the present invention was made to prevent this resulfurization.
  • desulfurization treatment was performed on hot metal using a CaO-based desulfurization agent in a mechanical stirring desulfurization apparatus, and then desulfurization treatment was performed.
  • a mechanical stirring type desulfurization device inert gas was blown into the hot metal in the processing vessel subjected to the desulfurization treatment from the gas outlet hole installed in the impeller of the mechanical stirring type desulfurization device, and the hot metal was stirred and suspended in the hot metal.
  • Turbid desulfurization slag and / or desulfurization slag adhering to the inner wall of the processing vessel is forcibly floated on the hot metal bath surface, and the levitated desulfurization slag is discharged from the processing vessel, and then the hot metal in the processing vessel is removed in the next step. It is transported to the phosphorus treatment process and decarburization refining process.
  • the inert gas is blown into the hot metal from the gas ejection hole installed in the impeller, the hot metal is stirred, and the desulfurized slag suspended in the hot metal and / or the desulfurized slag adhering to the inner wall of the processing vessel is bathed.
  • the process of forcibly ascending to the surface is called “desulfurization slag levitation / separation process”.
  • the above description is a mechanical stirring type desulfurization apparatus that has been subjected to desulfurization treatment, and the desulfurization slag flotation / separation process has been carried out following the desulfurization process, but is different from the mechanical stirring type desulfurization apparatus that has been subjected to desulfurization treatment.
  • the desulfurization slag flotation / separation step may be performed with the mechanical stirring type desulfurization apparatus. Needless to say, the same mechanical stirring type desulfurization apparatus is preferable because of high productivity.
  • Fig. 1 is a schematic diagram showing an example of the desulfurization slag flotation / separation process.
  • reference numeral 1 is a carriage
  • 2 is a processing vessel (hot metal ladle)
  • 3 is hot metal
  • 4 is an impeller
  • 5 is a rotating shaft of the impeller
  • 6 is a gas ejection hole installed on a blade of the impeller.
  • the mechanical stirring type desulfurization apparatus includes a refractory impeller 4 that is immersed and buried in a hot metal 3 accommodated in a processing vessel 2 loaded on a carriage 1 and rotates to stir the hot metal 3.
  • the impeller 4 is configured to move up and down in a substantially vertical direction by an elevating device (not shown) and to rotate about a rotation shaft 5 by a rotating device (not shown).
  • the impeller 4 is composed of a plurality of blades projecting radially from the rotating shaft 5, and gas ejection holes 6 are provided on the side surfaces of the blades on the rotation circumference side. That is, the gas ejection holes 6 are opened at the tip surfaces of the blades that project radially, and the inert gas is configured to be ejected through the gas ejection holes 6 in a direction perpendicular to the rotation shaft 5. .
  • At least one gas ejection hole 6 is installed on any blade of the impeller. That is, one or more gas ejection holes 6 are installed per impeller.
  • a gas supply pipe (not shown) communicating with the gas ejection hole 6 is provided inside the rotary shaft 5, and an inert gas supplied from the upper part of the rotary shaft 5 supplies gas inside the rotary shaft 5. It passes through the pipe and reaches the gas ejection hole 6 installed in the blade, and is blown into the hot metal 3 from the tip of the gas ejection hole 6 to stir the hot metal 3.
  • the height distance in the vertical direction of any two gas ejection holes is preferably 100 mm or more.
  • the impeller In the desulfurization slag flotation / separation process, it does not matter whether the impeller is rotated or not. However, by rotating the impeller, the inert gas ejection position from the impeller blades is dispersed in the processing vessel, and the rising of the desulfurized slag is promoted. Therefore, it is preferable to rotate the impeller.
  • the impeller When rotating the impeller, it is preferable to control the shape of the vortex formed by the rotation of the impeller. That is, the position of the impeller and the setting position of the impeller so that the distance from the stationary molten metal surface of the hot metal in the processing vessel to the recess of the vortex center formed by the rotation of the impeller is smaller than the distance from the stationary molten metal surface to the upper end of the impeller. It is preferable to adjust the rotational speed of the impeller.
  • the distance from the stationary hot water surface to the recess at the center of the vortex is usually larger than the distance from the stationary hot water surface to the upper end of the impeller. This is performed by adjusting the setting position of the impeller and / or the rotation speed of the impeller so as to increase (see, for example, FIGS. 1 and 2 of Patent Document 4).
  • the desulfurization slag flotation / separation step in order to promote the desulfurization slag flotation, it is preferable to have a positional relationship opposite to that of the desulfurization treatment as described above.
  • the dent depth at the center of the vortex is smaller than the immersion depth at the upper end position of the impeller.
  • the present inventors have proposed that the dent depth at the center of the vortex can be calculated from the stirring conditions such as the shape of the impeller, the shape of the processing vessel, and the number of revolutions of the impeller (see Japanese Patent No. 4998676). ). Using this calculation technique, it may be confirmed that the dent depth at the center of the vortex is smaller than the immersion depth at the impeller upper end position.
  • FIG. 2 shows an outline when the hot metal is stirred with an impeller to form a vortex in a mechanical stirring type desulfurization apparatus.
  • 2 is a processing vessel (hot metal ladle)
  • 3 is hot metal
  • 4 is an impeller having a plurality of blades
  • 5 is a rotating shaft of the impeller
  • 7 is a stationary hot water surface of the hot metal
  • H is a depth of recess at the center of the vortex.
  • h is the immersion depth at the impeller upper end position (blade upper surface position).
  • the hot metal 3 accommodated in the processing vessel 2 having an inner diameter D is immersed in an impeller 4 having a rotational diameter of d, a height of b, and a blade inclination angle ⁇ , and the hot metal 3 is stirred.
  • the static hot water surface 7 of the hot metal 3 is a hot water surface level when the impeller 4 is immersed in the hot metal 3.
  • a vortex centered on the rotating shaft 5 of the impeller 4 is formed in the hot metal 3, and the dent depth (H) of this vortex center is analyzed as a distance from the stationary molten metal surface 7, and the immersion depth at the upper end position of the impeller (H) is analyzed as a distance from the stationary hot water surface 7.
  • the depth of depression (H) at the center of the vortex under various stirring conditions is measured, and the impeller rotation speed, the inner diameter (D) of the processing vessel, the impeller rotation diameter ( d)
  • the depth (H) of the vortex center was obtained by a calculation formula using the impeller height (b), the impeller blade inclination angle ( ⁇ ), and the like.
  • the recess depth (H) at the vortex center can be calculated by using the following equations (1) to (4).
  • H is the depth of the recess at the center of the vortex (m)
  • N is the rotational speed of the impeller (times / min)
  • D is the inner diameter (m) of the processing vessel
  • ⁇ is the impeller.
  • b is the impeller height (m)
  • d is the impeller rotational diameter (m)
  • n P is the number of impeller blades
  • Re is the number of ray nozzles (dimensionless)
  • ⁇ is the density (kg / m 3 ) of the molten metal
  • ⁇ is the viscosity (Pa ⁇ s) of the molten metal.
  • the depth (H) of the vortex center from the stationary molten metal surface 7 calculated using the equations (1) to (4) obtained in this water model experiment, and the stationary molten metal surface in the hot metal 3 in the actual machine.
  • the measured value of the dent center depression depth (H) from 7 was compared. As a result, they are in good agreement, and it is confirmed that the depth of depression (H) at the center of the vortex can be estimated using the above formula without actually measuring in the stirring of the hot metal 3 using the impeller 4. did.
  • processing containers have an elliptical cross section
  • processing containers that have a circular cross section but have side surfaces that expand upward.
  • the inner diameter (D) of the processing vessel is an average value of the major axis and the minor axis when the cross section is elliptical, and is in a range where it contacts the hot metal when the side surface expands upward. What is necessary is just to set it as the average value of an internal diameter.
  • impellers having different upper end diameters and lower end diameters.
  • the rotational diameter (d) of the impeller may be an average value of the upper end diameter and the lower end diameter.
  • the inventors of the present invention have determined that the dent center depression depth (H) with respect to the stationary hot water surface 7 is the size of the processing vessel and the hot metal treatment as shown in the above equations (1) to (4). It was confirmed that it was uniquely determined by the amount, the shape and rotation speed of the impeller, the physical property value of the hot metal, and the like.
  • the immersion depth (h) at the upper end position of the impeller is calculated from the descending distance from the reference position of the impeller 4 and the hot metal surface position when the impeller 4 is buried.
  • the dent center depression depth (H) calculated by the equations (1) to (4) is the immersion depth (h)
  • the recess depth (H) at the center of the vortex is 100 mm or more smaller than the immersion depth (h) at the impeller upper end position.
  • the hot metal 3 is agitated under the condition that the recess depth (H) of the vortex center calculated by the equations (1) to (4) is larger than the immersion depth (h) at the upper end position of the impeller. It is preferable.
  • the rotation of the impeller is apparent from the equations (1) to (4). It can be seen that the number (N) should be reduced. In the formulas (1) to (4), other conditions cannot be changed unless the processing vessel and the impeller are changed. Further, even if the recess depth (H) at the center of the vortex is the same as that during the desulfurization process, the impeller is lowered so that the immersion depth (h) at the upper end position of the impeller is larger than the recess depth (H) at the center of the vortex. Then, the intended desulfurization slag levitation / separation step can be performed.
  • the desulfurization slag flotation / separation step is performed by increasing the immersion depth (h) at the upper end position of the impeller and / or decreasing the rotation speed (N) of the impeller.
  • the desulfurization slag flotation / separation process temporarily stop the impeller rotation from the stirring state during the desulfurization process, and then deepen the impeller immersion position and / or rotate the impeller again at a low speed. Also good.
  • the impeller may be deepened after the impeller rotation speed is reduced from the stirring state during the desulfurization process or the impeller rotation speed is reduced to a predetermined rotation speed.
  • the desulfurization slag suspended in the hot metal or the desulfurization slag adhering to the inner wall of the treatment vessel is removed from the treatment vessel, so that the desulfurization slag carried over to the next dephosphorization treatment step and the decarburization refining step is reduced. Resulfurization in the treatment process and decarburization refining process is suppressed.
  • the inert gas blown from the gas ejection hole of the impeller a rare gas such as an argon gas or a nitrogen gas can be used.
  • the flow rate of the inert gas is preferably 0.010 Nm 3 / (min ⁇ molten-ton) or more.
  • the stirring force is weak and the desulfurized slag suspended in the molten iron and the desulfurized slag adhering to the inner wall of the processing vessel are sufficiently floated. This is because it is not possible to suppress the sulfurization sufficiently.
  • the upper limit of the inert gas blowing flow rate does not need to be specified, but even if it is blown in a large amount, the effect of preventing resulfurization is saturated, and there is no effect of preventing further resulfurization. Impedes operation due to the occurrence of splash and a decrease in hot metal temperature. Therefore, an upper limit of about 0.10 Nm 3 / (min ⁇ molten-ton) is sufficient.
  • the hot metal desulfurization treatment uses a mechanical stirring type desulfurization apparatus having the configuration shown in FIG. 1, and immerses the impeller in the hot metal contained in a ladle-type treatment vessel, and rotates the impeller so that the hot metal, the CaO-based desulfurization agent, Is carried out with stirring.
  • the following method can be used. For example, a method of tilting the processing container to such an extent that molten iron does not flow out and drawing it mechanically using a slag scraping machine or the like, or a method of removing by suction using a vacuum slag removing device can be used. After the desulfurization slag is discharged, it is preferable to add a heat retaining agent in the processing container in order to prevent the hot metal temperature from decreasing.
  • the hot metal to be used is a hot metal melted in a blast furnace or a shaft furnace, and may be subjected to desiliconization treatment or dephosphorization treatment before desulfurization treatment.
  • the next step is decarburization refining step in the converter, so removal treatment of desulfurized slag forcedly levitated by stirring with inert gas from the treatment vessel After that, the hot metal is transported to a converter where decarburization is performed.
  • the dephosphorization of hot metal is performed as a preliminary treatment after the desulfurization treatment
  • the next step is a dephosphorization treatment step. Therefore, the desulfurization slag from the treatment vessel forcedly levitated by stirring with an inert gas is removed.
  • the hot metal after the removal treatment is transported to a facility for performing the dephosphorization treatment.
  • the desulfurized slag remaining in the processing vessel is forcibly levitated by stirring with an inert gas, and the levitated desulfurized slag is discharged from the processing vessel. Used for dephosphorization process and decarburization refining. As a result, most of the desulfurization slag that causes resulfurization is removed when dephosphorization treatment and decarburization refining, and it is possible to reduce resulfurization in dephosphorization treatment and decarburization refining. .
  • the conventional melting method and the present invention melting method are carried out for 150 charges each. Then, a test for comparing the sulfur concentration in the hot metal at the end of the dephosphorization process in the next step was conducted. If there is a difference in the sulfur concentration in the hot metal at the end of the dephosphorization treatment, it is due to the difference in the amount of sulfurization.
  • the conventional melting method removes the desulfurization slag by removing the desulfurization slag covering the hot metal bath surface without performing the desulfurization slag flotation / separation process after the desulfurization treatment with the CaO-based desulfurization agent in the mechanical stirring type desulfurization apparatus. Then, the low-sulfur steel is melted immediately after the dephosphorization treatment step and the decarburization refining step of the next step.
  • the desulfurization slag is floated and separated by blowing inert gas from the gas injection holes installed in the impeller after the desulfurization treatment with the CaO-based desulfurization agent in the mechanical stirring desulfurization apparatus. This is a melting method in which desulfurization slag covering the hot metal bath surface is removed after the floatation / separation step, and then low-sulfur steel is melted through the following dephosphorization treatment step and decarburization refining step.
  • a specific test method is to use a CaO-CaF 2 desulfurization agent as a CaO-based desulfurization agent, and perform desulfurization treatment of the hot metal in the hot metal ladle with a mechanical stirring type desulfurization device, and the sulfur concentration of the hot metal is 0.0010% by mass or less. Lowered to. The sulfur concentration of the hot metal after the desulfurization treatment was 0.0006% by mass.
  • the impeller A has one gas ejection hole on the rotation circumferential side surface of one blade.
  • the impellers B and C each have one gas ejection hole on the rotation circumferential side surface of two blades on a diagonal line.
  • the impeller B has two gas ejection holes installed at the same height in the vertical direction, and the impeller C has two gas ejection holes installed at different height positions in the vertical direction.
  • the two gas ejection holes of the impeller C are installed at positions 100 mm apart in the vertical direction.
  • the impeller D is an impeller that is used in the conventional melting method and does not have a gas ejection hole.
  • the chemical components before desulfurization treatment of the hot metal used were C: 3.5 to 5.0% by mass, Si: 0.1 to 0.3% by mass, S: 0.025 to 0.035% by mass, P: The hot metal temperature was in the range of 1250 to 1350 ° C. at 0.10 to 0.15 mass%.
  • the basic unit of the desulfurizing agent used was 5.0 to 7.5 kg / molten iron-ton.
  • desulfurization treatment is performed using the impeller D, and the desulfurization slag discharge process for removing the desulfurization slag covering the hot metal bath surface from the hot metal ladle, charging of the hot metal from the hot metal pan to the charging pan, and charging Filling the hot metal from the pan into the converter, dephosphorizing the hot metal in the converter, tapping the hot water into the charging pan after the dephosphorization, removing the dephosphorization slag from the charging pan after tapping, charging pan
  • the hot metal was charged into the converter and the decarburization refining of the hot metal in the converter was performed in this order.
  • desulfurization treatment is performed using impellers A, B, and C, and after desulfurization treatment, desulfurization is performed by blowing inert gas from the respective gas ejection holes installed in impellers A, B, and C.
  • Slag levitation / separation process desulfurization slag removal process to remove the desulfurized slag slag from hot metal ladle, hot metal charging from hot metal ladle to charging pan, hot metal charging from charging pan to converter, converter Dephosphorization of hot metal in the furnace, tapping into the charging pan after dephosphorization, removal of dephosphorization slag after tapping from the charging pan, charging of hot metal from the charging pan to the converter, The decarburization and refining of the hot metal was performed in this order.
  • the dephosphorization treatment was performed without adding an auxiliary material that causes the sulfur content of the hot metal to increase during the dephosphorization treatment.
  • an analytical sample was collected from the molten iron and analyzed for the sulfur concentration of the analytical sample.
  • Table 1 shows the average value of the amount of sulfurization in the conventional melting method and the present invention melting method.
  • the amount of resulfurization was defined as the difference between the sulfur concentration in the hot metal at the end of the dephosphorization treatment and the sulfur concentration in the hot metal after the desulfurization slag discharge step. After decarburization and refining, it has been confirmed that the amount of sulfurization is zero.
  • the melting method of the present invention shown in Table 1 is the data when impeller A is used, and in the desulfurization slag flotation / separation process, argon gas of 0.10 Nm 3 / (min ⁇ molten-ton) is blown for 30 seconds. is there.
  • the sulfur concentration in the molten steel was increased by resulfurization, and the amount of resulfurization was 0.0052% by mass on the average of 150 charges tested.
  • the amount of resulfurization was 0.0007% by mass to 0.0015% by mass, and the average was 0.0011% by mass, which was remarkably reduced.
  • the desulfurization slag flotation / separation step after the desulfurization treatment was performed by blowing argon gas of 0.10 Nm 3 / (min ⁇ molten-ton) for 30 seconds.
  • argon gas was not blown in, but the rotation speed of the impeller was changed to change the distance (H), and the state was maintained for 30 seconds.
  • Table 2 shows the treatment conditions and the amount of sulfurization.
  • the amount of resulfurization was 0.0005 to 0.0015% by mass, which was reduced to less than half the amount of resulfurization of Comparative Examples 1 and 2.
  • the amount of resulfurization is 0.0005 to 0.0010% by mass, and the amount of resulfurization is 0.0010% by mass or less. Is achieved, and the amount of resulfurization is greatly reduced compared to the amount of resulfurization (0.0010 to 0.0015 mass%) of Examples 1, 3, and 5 of the present invention in which the distance (H) is larger than the distance (h). We were able to. That is, it was confirmed that the amount of resulfurization was reduced by making the distance (H) smaller than the distance (h).
  • impeller A present invention example 2
  • impeller B present invention example 2
  • present invention examples 2, 4, and 6 where the distance (H) is smaller than the distance (h).
  • the amount of sulfurization is the same, whereas in the impeller C (invention example 6), the amount of sulfurization was greatly reduced.
  • the amount of resulfurization can be particularly reduced by installing one gas ejection hole at a different height position in the vertical direction on the side surface of the rotation circumference of the two blades on the diagonal line.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)

Abstract

　La présente invention permet d'empêcher, dans un procédé de fabrication d'acier à l'état liquide à partir de fonte brute à l'état liquide dans lequel une étape subséquente de décarburation est effectuée après un traitement de désulfuration, la resulfuration causée par des scories générées au moment du traitement de désulfuration d'une fonte brute à l'état liquide, lesquelles scories adhèrent aux parois d'une cuve de traitement ou, sous forme de micro-scories, se retrouvent en suspension dans l'acier à l'état liquide.　Ce procédé pour empêcher la resulfuration d'une fonte brute après un traitement de désulfuration consiste à : effectuer une désulfuration d'une fonte brute à l'état liquide dans une cuve de traitement au moyen d'un dispositif mécanique de désulfuration par brassage; introduire un gaz inerte dans la fonte brute à l'état liquide à partir de trous (6) d'éjection de gaz situés dans l'agitateur (4) du dispositif mécanique de désulfuration par brassage puis à brasser la fonte brute (3) à l'état liquide; faire flotter au moyen de ce brassage, les scories de désulfuration en suspension dans la fonte brute à l'état liquide et/ou les scories de désulfuration qui ont adhéré aux parois internes de la cuve de traitement à la surface de la fonte brute à l'état liquide; évacuer de la cuve de traitement les scories de désulfuration flottantes; puis amener la fonte brute à l'état liquide à l'étape suivante.
PCT/JP2015/000001 2014-01-10 2015-01-05 Procédé pour empêcher la resulfuration d'une fonte brute à l'état liquide après traitement de désulfuration WO2015105035A1 (fr)

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KR1020167021363A KR101840962B1 (ko) 2014-01-10 2015-01-05 탈황 처리 후의 용선의 복황 방지 방법
JP2015556780A JP6052436B2 (ja) 2014-01-10 2015-01-05 脱硫処理後の溶銑の復硫防止方法
CN201580004067.5A CN105899689B (zh) 2014-01-10 2015-01-05 脱硫处理后的铁水的回硫防止方法
BR112015009665A BR112015009665A2 (pt) 2014-01-10 2015-01-05 método para suprimir ressulfurização de metal quente após tratamento de dessulfurização

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JP2003342626A (ja) * 2002-05-30 2003-12-03 Jfe Steel Kk 溶融金属の回転攪拌装置およびそれを用いた溶融金属の脱硫方法
JP2006028615A (ja) * 2004-07-20 2006-02-02 Sumitomo Metal Ind Ltd 溶銑の脱硫方法及び機械式攪拌装置。
JP2013237892A (ja) * 2012-05-15 2013-11-28 Jfe Steel Corp 脱硫処理後の溶銑の復硫防止方法

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JPH0499212A (ja) * 1990-08-08 1992-03-31 Sumitomo Metal Ind Ltd 溶銑の脱硫装置
JPH04235210A (ja) 1991-01-10 1992-08-24 Sumitomo Metal Ind Ltd 溶銑脱硫方法
JP2856106B2 (ja) 1995-03-30 1999-02-10 住友金属工業株式会社 溶銑の脱硫方法
JP2001247910A (ja) * 2000-03-03 2001-09-14 Nippon Steel Corp 溶銑の攪拌方法
JP2005200762A (ja) 2003-12-16 2005-07-28 Sumitomo Metal Ind Ltd 溶銑の脱硫方法
JP4998676B2 (ja) * 2006-03-29 2012-08-15 Ｊｆｅスチール株式会社 インペラーを用いた溶融金属の攪拌方法
CN103014218B (zh) * 2012-12-30 2014-09-03 大冶特殊钢股份有限公司 Kr搅拌桨及其制作方法

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Publication number Priority date Publication date Assignee Title
JP2003342626A (ja) * 2002-05-30 2003-12-03 Jfe Steel Kk 溶融金属の回転攪拌装置およびそれを用いた溶融金属の脱硫方法
JP2006028615A (ja) * 2004-07-20 2006-02-02 Sumitomo Metal Ind Ltd 溶銑の脱硫方法及び機械式攪拌装置。
JP2013237892A (ja) * 2012-05-15 2013-11-28 Jfe Steel Corp 脱硫処理後の溶銑の復硫防止方法

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JPWO2015105035A1 (ja) 2017-03-23
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CN105899689B (zh) 2019-05-07
TW201540842A (zh) 2015-11-01
KR101840962B1 (ko) 2018-03-21
TWI564396B (zh) 2017-01-01
KR20160106130A (ko) 2016-09-09
BR112015009665A2 (pt) 2017-07-04

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