WO2023185874A1 - 一种减少钢液中细微夹杂物的方法及装置 - Google Patents

一种减少钢液中细微夹杂物的方法及装置 Download PDF

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Publication number
WO2023185874A1
WO2023185874A1 PCT/CN2023/084475 CN2023084475W WO2023185874A1 WO 2023185874 A1 WO2023185874 A1 WO 2023185874A1 CN 2023084475 W CN2023084475 W CN 2023084475W WO 2023185874 A1 WO2023185874 A1 WO 2023185874A1
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WIPO (PCT)
Prior art keywords
flow
retaining wall
diversion
molten steel
tundish
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PCT/CN2023/084475
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English (en)
French (fr)
Inventor
甘菲芳
高华
李济永
陈兆平
蒋晓放
徐国栋
梅峰
杨光维
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宝山钢铁股份有限公司
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Publication of WO2023185874A1 publication Critical patent/WO2023185874A1/zh

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D41/00—Casting melt-holding vessels, e.g. ladles, tundishes, cups or the like
    • B22D41/02—Linings
    • 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 the field of steelmaking, and in particular to a method and device for reducing fine inclusions in molten steel.
  • Inclusions in molten steel are important factors affecting the production and application of steel.
  • the quantity, size and degree of dispersion of inclusions in steel have a great impact on its quality.
  • Effective control of non-metallic inclusions in steel is the key to improving the quality of steel products.
  • the essential As people have higher and higher requirements for steel cleanliness and the continuous improvement of performance requirements in specific steels, the removal of inclusions below 20 ⁇ m continues to receive attention, especially high-clean steel, such as pipeline steel, automotive sheet steel, and high-grade silicon steel. wait.
  • Inclusion control is related to every process in the entire steel production process. Therefore, the control of inclusions in molten steel usually involves the entire steel production process including molten iron pretreatment, smelting, refining, continuous casting, etc.
  • Chinese patent CN102676725A discloses a method for controlling inclusions in steel, which includes the following steps: 1) Injecting Mg for strong desulfurization to pretreat molten iron; 2) Adding fluorite, active lime, aluminum blocks and alloys to the converter tapping for pretreatment Refining; 3) Deep desulfurization during the refining process, using high alkalinity and strong reducing slag to control the S content in the molten steel; the LF treatment process satisfies [Als] between 0.03 and 0.06%; 4) Vacuum treatment of the molten steel, Ca treatment was performed after vacuum treatment.
  • Chinese patent CN102816898A discloses a method for improving top slag modification, which is used to reduce the oxidation property of top slag.
  • the composite deoxidizer is added twice, and argon is blown to adjust the composition of the molten steel.
  • the composite deoxidizer is added to the top slag of the ladle for the third time. This reduces the number of inclusions in IF steel and improves the surface quality of automotive panels.
  • Chinese patent CN103014220A discloses a composition for improving non-metallic inclusions in molten steel. Methods to improve the purity of liquid steel by forming and sizing it. By performing calcium treatment and soft blowing at the end of the LF refining whitening slag and at the end of the RH vacuum treatment, the chemical composition of the non-metallic inclusions is controlled, thereby changing the melting point of the non-metallic inclusions in the molten steel (1500°C ⁇ 1650°C ), shape and size. This can avoid cracks during the rolling and use of pipeline steel.
  • This solution is a method of modifying non-metallic inclusions, which can improve the quality qualification rate of steel products.
  • Chinese patent CN102517419A discloses a method for improving the cleanliness of molten steel and reducing the content of inclusions. It causes non-metallic inclusions in the steel to enter the plastic zone and changes the shape of the non-metallic inclusions, thereby improving the fatigue life of the steel.
  • the methods disclosed in this document include processes such as molten iron treatment, converter smelting, ladle refining and continuous casting. Especially in the continuous casting process, a mold powder with a basicity of 0.8 to 0.85 is used, and the crystallizer uses electromagnetic stirring. The main controls are current intensity and frequency. This technical solution controls inclusions by optimizing the entire steelmaking process, and the steel produced has good quality.
  • each step of the entire steelmaking process has corresponding processes for reducing and controlling inclusions in molten steel.
  • molten steel composition control can be used to optimize the chemical composition of molten steel, increase beneficial elements, and reduce harmful elements to reduce inclusions in molten steel.
  • chemical treatment mostly calcium and rare earth treatment, is used to remove oxygen and sulfur-based inclusions in steel as much as possible to control the shape of inclusions and improve the as-cast structure.
  • the steelmaking process is carried out through refining, slagging and modification or electromagnetic stirring.
  • the equipment used in the above-mentioned steelmaking process is complex, costly, and the process is difficult to control accurately. It is generally suitable for reducing the amount of large inclusions in steel.
  • the continuous casting tundish is regarded as an important metallurgical container connecting the ladle and the crystallizer. It can transport the molten steel with a predetermined flow rate and temperature to the crystallizer smoothly and pollution-free.
  • the control of molten steel inclusions in the tundish is the last and most critical process in the steelmaking and continuous casting process. The removal effect and mechanism of inclusions have attracted much attention.
  • the more common methods for removing inclusions from molten steel include bubble adsorption, electromagnetic stirring in the crystallizer, and filtration separation.
  • the methods for removing inclusions in the electromagnetic field in the crystallizer mainly include electromagnetic stirring and electromagnetic braking.
  • Electromagnetic stirring changes the flow field of molten steel in the crystallizer under the action of electromagnetic field force, eliminates the recirculation area, prolongs the residence time of inclusions in the molten steel, increases the collision probability of inclusions, and promotes inclusions in the crystallizer. The process of center collision, coalescence and floating to remove inclusions.
  • Electromagnetic braking is a process that generates electromagnetic force opposite to the flow direction of molten steel under the action of a magnetic field to reduce the impact depth of molten steel in the mold and prevent slag entrapment. This method has no special restrictions on inclusion size.
  • the electromagnetic purification method (including electromagnetic stirring and electromagnetic braking) is applicable to a wide range of processes and is relatively flexible in operation, but it requires complex equipment and consumes a large amount of power resources.
  • the filtration separation method can use a filtration device to directly purify the inclusions in the molten steel.
  • the manufacturing process of the filter is complex, the materials are expensive, it is easy to get clogged, and the replacement frequency is high. It cannot adapt to high-intensity and long-term continuous casting operations, so it has not been widely used in practical applications.
  • Inclusions present in high-clean steel such as pipeline steel
  • inclusions less than 20 ⁇ m will directly cause defects such as hydrogen-induced cracking of the steel, greatly affecting the performance of pipeline steel.
  • inclusions in steel also have a great impact on the physical properties of steel such as plasticity, toughness and fatigue strength. Therefore, in addition to taking necessary measures during the steelmaking and refining process, it is also necessary to develop a relatively simple, effective, and low-cost method that can reduce fine inclusions in the molten steel in the tundish, thereby improving the quality of steel products and market competition. force.
  • the purpose of the present invention is to provide a method and device for reducing fine inclusions in molten steel.
  • the flow field of molten steel in the ladle prolongs the residence time of the molten steel, promotes the collision, condensation and growth of fine inclusions with a size less than 20 ⁇ m, and fully floats, thus purifying the molten steel.
  • the first aspect of the present invention provides a method for reducing fine inclusions in molten steel, including:
  • An internal rotating flow stabilizer is provided below the inner bottom of the tundish corresponding to the long nozzle.
  • the internal rotating flow stabilizer has a circular shell with an upper end.
  • the internal bottom surface of the internal rotating flow stabilizer has a central edge along the At least three arc-shaped blocks (rectangular parallelepiped flow guide blocks distributed along the arc) are arranged circumferentially, and the side walls of the internal rotation flow stabilizer are provided with overflow holes;
  • the inner bottom of the tundish is each provided with a double-layer retaining wall structure.
  • the double-layer retaining wall structure includes a front porous diversion retaining wall and a rear porous diversion retaining wall arranged in sequence; the upper part of the front porous diversion retaining wall is preferably provided.
  • a plurality of upper diversion holes are evenly arranged, and a plurality of lower diversion holes are preferably evenly arranged at the lower part of the rear porous diversion retaining wall;
  • the molten steel enters the internal rotating flow stabilizer through the long nozzle.
  • the internal rotating flow stabilizer causes the molten steel to turn around, disrupting the initial flow field of the molten steel in the tundish and forming a swirling flow.
  • Micron-sized inclusions in the stream will gather toward the center, where they will collide and grow. Cluster-shaped inclusion particles reaching a certain size will float to the steel slag liquid surface under the action of Stokes buoyancy and be removed;
  • the molten steel enters the double-layer retaining wall structure from the upper diversion hole of the front porous diversion retaining wall.
  • the unsteady flowing molten steel obtains a stable flow field through the double-layer retaining wall structure and is evenly distributed in the front porous diversion retaining wall.
  • the upper diversion hole and the lower diversion hole of the rear porous diversion retaining wall change the movement trajectory of the molten steel; the upper and lower diversion holes in the front and rear porous diversion retaining walls in different directions are used to adjust the flow field of the molten steel in the tundish. direction, so that fine inclusions are adsorbed and removed by the top slag.
  • a second aspect of the present invention provides a device for the above method, comprising:
  • Double-layer retaining wall structures located on both sides of the internally rotating flow stabilizer; among which,
  • the internal rotating flow stabilizer is arranged below the corresponding long nozzle in the bottom of the tundish, and includes: a body, which is a circular shell with an upper end, and overflow holes are provided on both side walls of the body.
  • the overflow hole is The axis of the flow hole is at an angle to the horizontal direction;
  • the inner bottom surface of the body is provided with four rectangular parallelepiped flow guide blocks arranged in a circumferential direction, and the centers of each flow guide block are distributed on a positioning circle with the center of the inner bottom surface of the body as the center, and, Each guide block is deflected at an angle; preferably, the guide block forms an angle of 0 to 30° with the tangent line of the positioning circle;
  • the double-layer retaining wall structure is arranged in the middle injection area of the tundish on both sides of the internal rotation flow stabilizer, and a double-layer retaining wall structure is provided on both sides of the internal rotation flow stabilizer.
  • the double-layer retaining wall The structure consists of a front porous diversion retaining wall and a rear porous diversion retaining wall.
  • the upper part of the front porous diversion retaining wall is equipped with an upper diversion hole.
  • the lower part of the rear porous diversion retaining wall is provided with lower diversion holes; preferably, the bottoms of the front porous diversion retaining wall and/or the rear porous diversion retaining wall are also provided with flow diversion holes.
  • the outer diameter of the internal rotating flow stabilizer is the same as the width of the inner bottom of the tundish.
  • the axis of the upper guide hole of the front porous flow guide retaining wall and/or the lower guide hole of the rear porous flow guide retaining wall is at an angle of 20 to 40° with the horizontal.
  • the upper guide hole and/or Or the diameter of the lower guide hole is 40 ⁇ 60mm.
  • the distance between the front porous flow diversion retaining wall and the rear porous flow diversion retaining wall is 300 to 400 mm.
  • the front porous diversion retaining wall is 1500 to 1800 mm away from the center line of the long nozzle.
  • the internal swirling flow stabilizer and the front and rear porous diversion retaining walls are made of refractory materials.
  • the weight percentage of the chemical composition of the refractory materials is: MgO+Al 2 O 3 >90.0%, Fe 2 O 3 ⁇ 0.85%; the compressive strength of the refractory material is ⁇ 50MPa, and the volume density is ⁇ 2.75g/cm 3 .
  • the present invention also provides an internal rotation flow stabilizer for implementing the above method.
  • the internal rotation flow stabilizer includes: a body, which is a circular shell with an upper end, and the two side walls of the body are symmetrically provided with overflows. hole, preferably, the axis of the overflow hole is at an angle to the horizontal direction (the axis deviates from the horizontal direction to facilitate the flow of residual molten steel in the internal rotating flow stabilizer); four rectangular parallelepiped flow guide blocks are provided along the circumferential direction on the inner bottom of the body.
  • each guide block is distributed on the circumference of a positioning circle with the center of the inner bottom surface of the body as the center, and each guide block is deflected at an angle (that is, the direction of the guide block deviates from the positioning circle at the center of the guide block (tangential direction at), preferably, the guide block and the tangent of the positioning circle form an angle of 0 to 30°.
  • the flow guide block is 160-170mm long, 40-50mm wide, and 30-40mm high.
  • the molten steel first impacts the internal rotating flow stabilizer at the bottom of the tundish through the long nozzle. Since the flow guide blocks are arranged circumferentially at the bottom of the internal rotating flow stabilizer, the opening of the pouring steel flow impacts the internal rotating flow stabilizer. The flow stabilizer turns in the cavity of the flow stabilizer, disrupting the initial flow field in the tundish and forming a swirling flow. Increasing the residence time of molten steel also increases the movement distance and collision probability of inclusions in the molten steel.
  • the molten steel flowing out from the long nozzle is faster and will form a high-pressure area in this area; when the molten steel flows out from the inner circle, it flows into the space between adjacent diversion blocks.
  • the channel that transitions from the inner circle to the outer circle gradually narrows. A small part of the molten steel accelerates through the channel and flows out of the outer circle area, but most of the molten steel flow is hindered to form an upward vortex and the subsequent secondary vortex; The central pressure of this strong vortex is low, causing the fine inclusions in the flow to gather toward the low-pressure center, where they will collide and grow. Cluster-like inclusion particles that reach a certain size will float under the action of Stokes buoyancy.
  • the pressure changes formed in the inner and outer circles of the internal rotating flow stabilizer can effectively break the fluid and prevent inclusion particles from entering the billet with the movement of the fluid at the bottom of the tundish and affecting product quality.
  • This step can greatly improve the removal efficiency of inclusions in the tundish, thereby helping to improve the cleanliness of the molten steel and thus the cleanliness of the formed steel.
  • the molten steel containing inclusions enters the double-layer retaining wall structure from the diversion hole of the front retaining wall.
  • the double-layer retaining wall is equivalent to an induction device for the flow of molten steel. The unsteady flowing molten steel is stabilized by the double-layer retaining wall.
  • the movement trajectory of the molten steel is changed through the diversion holes evenly distributed on the retaining wall to prevent short-circuit flow.
  • the diversion holes in different directions on the front and rear retaining walls are used to adjust the direction of the flow field of the molten steel in the ladle, so that fine inclusions can be adsorbed and removed by the top slag.
  • the porous retaining wall makes the distribution of molten steel distributed to each immersed nozzle more uniform, increases the average residence time of molten steel from the long nozzle of the ladle to the immersed nozzle of the tundish, and facilitates the floating of fine inclusions. In this way, after a series of refining process controls are used to reduce inclusions, the molten steel is again removed from fine inclusions in the tundish to achieve high purity of the molten steel.
  • An internal rotating flow stabilizer is installed below the long nozzle of the tundish.
  • the internal rotating flow stabilizer can prevent the molten steel from splashing.
  • the circumferential direction of the bottom of the internal rotating flow stabilizer (surrounding the inner)
  • the flow guide blocks are arranged at intervals along the axial direction of the rotary flow stabilizer, so that the molten steel generates a swirl zone, and the molten steel undergoes regular turbulent collisions, which can prolong the residence time of the molten steel and facilitate the movement of micron-level fine inclusions in the molten steel to the center. Aggregated collisions grow up and are removed.
  • the internal setting of the internal rotating flow stabilizer has a certain deflection angle in the tangent direction of the positioning circle.
  • the rectangular guide block makes the molten steel in the middle injection area below the long nozzle in the tundish form a swirling flow, and the centrifugal force generated promotes the accumulation and growth of micron-level inclusions toward the center, which is beneficial to floating removal;
  • the swirling flow of molten steel in the injection zone in the tundish is beneficial to the mixing of the molten steel, extending the flow path, increasing the residence time of the molten steel and inclusions in the injection zone, and facilitating the removal of inclusions.
  • the double-layer retaining wall structure can effectively change the flow field of molten steel in the tundish, reduce the erosion of the bottom of the tundish, eliminate short-circuit flow, limit strong turbulence in the impact zone, and make the flow of molten steel near the water inlet of the tundish tend to be more stable. It is stable and the streamline is lengthened;
  • Diversion holes are provided on the upper part of the front porous diversion retaining wall and the lower part of the rear porous diversion retaining wall to divert the flow of molten steel;
  • the internal swirling flow stabilizer and the front and rear porous diversion retaining walls are all made of refractory materials.
  • the refractory materials contain MgO+Al 2 O 3 >90.0% and Fe 2 O 3 ⁇ 0.85% in terms of mass percentage.
  • the compressive strength of the refractory material is ⁇ 50MPa and the volume density is ⁇ 2.75g/cm 3 , which can meet the life requirements of the steel mill for the number of continuous pouring furnaces.
  • the last refractory container that the molten steel needs to pass through before entering the crystallizer is the tundish.
  • the cleanliness of the molten steel depends on the movement mode of the molten steel in the tundish and the type of refractory materials. closely related.
  • various flow control devices are designed in the continuous casting tundish to promote the floating removal of inclusions.
  • inclusions with a diameter less than 20 ⁇ m are difficult to float and remove in the continuous casting tundish. Therefore, the removal of fine inclusions below 20 ⁇ m has increasingly become a difficulty limiting the cleanliness of steel.
  • the present invention provides a solution of installing an internal rotating flow stabilizer + a double-layer diversion retaining wall in the tundish to reduce fine inclusions in the molten steel in the tundish.
  • the device of the present invention can effectively suppress the turbulent kinetic energy of the molten steel in the middle injection zone, form a swirling flow, and cause micron-level inclusions to gather and grow toward the center, which is conducive to the floating and removal of fine inclusions; at the same time, the flow path of the molten steel is optimized to prevent short-circuit flow.
  • Using the device of the present invention for continuous casting can fully ensure the high purity of molten steel required to form high-quality steel, greatly reduce defects such as hydrogen-induced cracking of steel products, and improve the quality of high-clean steel such as pipeline steel.
  • Figure 1 is a schematic structural diagram of the device in the present invention.
  • Figure 2 is a top view of the internally rotating flow stabilizer in the present invention.
  • Figure 3 is a front view of the internally rotating flow stabilizer in the present invention.
  • Figure 4 is a front view of the front porous diversion retaining wall in the present invention.
  • Figure 5 is a side view of the front porous diversion retaining wall in the present invention.
  • Figure 6 is a front view of the rear porous diversion retaining wall in the present invention.
  • Figure 7 is a side view of the rear porous diversion retaining wall in the present invention.
  • Figure 8 is a perspective view of the device of the present invention.
  • the method of reducing fine inclusions in molten steel according to the present invention includes:
  • An internal rotating flow stabilizer 2 is provided below the long nozzle 100 in the inner bottom of the tundish 1.
  • the internal rotating flow stabilizer 2 has a circular shell with an upper end open, and its inner bottom surface is along the circumferential direction.
  • At least three arc-shaped blocks 3 i.e.
  • rectangular parallelepiped flow guide blocks are arranged at intervals, the circumferential direction surrounds the axial direction of the housing, and the side wall of the internal rotation stabilizer 2 is provided with an overflow hole 22, preferably , the axis of the overflow hole 22 forms an angle with the horizontal direction;
  • the inner bottoms of the tundish 1 on both sides of the internal rotation flow stabilizer 2 are respectively provided with front porous diversion retaining walls 4 and rear porous diversion retaining walls 5, forming Double-layer retaining wall structure;
  • the upper part of the front porous diversion retaining wall 4 and the lower part of the rear porous diversion retaining wall 5 are evenly provided with a plurality of upper diversion holes 41 and lower diversion holes 51 respectively;
  • the molten steel enters the internal rotating flow stabilizer 2 through the long nozzle 100.
  • the internal rotating flow stabilizer 2 causes the molten steel to divert during pouring, disrupting the initial flow field of the molten steel in the tundish 1 and forming
  • micron-sized inclusions in the swirling flow stream will gather toward the center, where they will collide and grow. Clustered inclusion particles reaching a certain size will float to the surface of the steel slag under the action of Stokes buoyancy. to be removed;
  • the molten steel enters the double-layer retaining wall structure from the upper diversion hole 41 of the front porous diversion retaining wall 4.
  • the unsteady flowing molten steel obtains a stable flow field through the double-layer retaining wall structure and is evenly distributed in the front and rear porous walls.
  • the upper and lower diversion holes 41 and 51 of the diversion retaining walls 4 and 5 change the movement trajectory of the molten steel; the upper and lower diversion holes 41 and 51 of the front and rear porous diversion retaining walls 4 and 5 in different directions are used to adjust the center
  • the direction of the flow field of molten steel in ladle 1 causes fine inclusions to be adsorbed and removed by the top slag.
  • step b) there is no need to specify the size of the inclusion particle clusters generated during the movement of the molten steel in the internal rotation stabilizer. As long as the inclusion particle clusters can float to the steel slag liquid surface, they can be effectively removed.
  • the device used for the method of reducing fine inclusions in molten steel according to the present invention includes: a tundish 1, an internal rotating flow stabilizer 2 arranged in the tundish 1 and a The double-layer retaining wall structure on both sides of the internal rotating flow stabilizer 2;
  • the internal rotating flow stabilizer 2 is arranged below the corresponding long nozzle 100 in the inner bottom of the tundish 1, and includes: a body 21, which is a circular shell with an upper end, and overflow holes 22 are provided on both sides of the body. , preferably, the axis of the overflow hole 22 is at an angle to the horizontal direction; the inner bottom surface of the body 21 is provided with four rectangular parallelepiped flow guide blocks 3 spaced apart in the circumferential direction (around the axis direction of the body), and the center of each flow guide block 3 are evenly distributed on a positioning circle a with the center of the inner bottom surface of the body 21 as the center, and each guide block 3 is deflected at an angle (that is, the direction of the guide block deviates from the tangent direction of the positioning circle). Preferably, the guide blocks 3 are deflected at an angle.
  • the tangent line between the flow block 3 and the positioning circle a forms an angle of 0 to 30°;
  • the double-layer retaining wall structure is arranged in the middle injection area of the tundish 1, and a double-layer retaining wall structure is provided on both sides of the internal rotation flow stabilizer.
  • the double-layer retaining wall structure includes front and rear porous diversion retaining walls 4 ,5.
  • the upper part of the front porous flow diversion retaining wall 4 is provided with an upper flow guide hole 41
  • the lower part of the rear porous flow diversion block wall 5 is provided with a lower flow guide hole 51 .
  • See Figure 4-7 for the specific structure.
  • the arrow directions in Figures 5 and 7 are the flow directions of molten steel.
  • the bottoms of the front porous flow guide retaining wall and/or the rear porous flow guide retaining wall are also provided with flow guide holes.
  • the outer diameter of the internal rotating flow stabilizer 2 is the same as the width of the inner bottom of the tundish 1 .
  • the outer diameter of the internal rotating flow stabilizer 2 is the same as the width of the bottom of the tundish 1, so that the internal rotating flow stabilizer 2 can be placed exactly inside the tundish 1.
  • the axis of the upper guide hole 41 and/or the lower guide hole 51 of the front and rear porous flow guide retaining walls 4 and 5 is at an angle of 20 to 40° with the horizontal.
  • the upper guide hole and/or the lower guide hole 51 are Or the diameter of the lower guide hole is 40 ⁇ 60mm.
  • the distance between the front porous flow diversion retaining wall 4 and the rear porous flow diversion retaining wall 5 is 300 to 400 mm.
  • the front porous diversion retaining wall 4 is 1500-1800 mm away from the center line of the long nozzle 100.
  • the center line connecting the overflow holes 22 on both sides of the internal rotation flow stabilizer 2 is used as the positioning line, and the angle between the line connecting the center of the flow guide block 3 and the center of the positioning circle and the positioning line is ⁇ 1.
  • ⁇ 1 65 ⁇ 70°; preferably, the center lines of each flow guide block 3 are perpendicular to each other.
  • the internal swirling flow stabilizer and the front and rear porous diversion retaining walls are made of refractory materials.
  • the weight percentage of the chemical composition of the refractory materials is: MgO+Al 2 O 3 >90.0%, Fe 2 O 3 ⁇ 0.85%, the compressive strength of the material is ⁇ 50MPa, and the volume density is ⁇ 2.75g/cm 3 .
  • the refractory material selected in the present invention is the commonly used MgO-Al 2 O 3- based refractory material, which has good high temperature resistance, thermal shock resistance and slag corrosion resistance. Fe 2 O 3 is an impurity in the material, and the lower the content, the better.
  • the compressive strength of refractory materials is usually above 50MPa, for example, 50-80MPa. Materials with a strength of 50-70MPa or 50-60MPa can also be selected according to actual needs.
  • the volume density of refractory materials is usually above 2.75g/cm 3 , for example, 2.75-3.00g/cm 3 .
  • Figures 2 and 3 show the internal rotating flow stabilizer 2 used for reducing fine inclusions in molten steel according to the present invention, which includes: a body 21, which is a circular shell with an open upper end, and the two side walls of the body 21 are symmetrical Each is provided with an overflow hole 22; the inner bottom surface of the body 21 is provided with four rectangular parallelepiped flow guide blocks 3 arranged in an annular manner (that is, arranged in a circumferential direction, and the circumferential direction surrounds the axial direction of the body).
  • Each rectangular parallelepiped flow guide block 3 The centers are all distributed on the circumference of a positioning circle a with the center of the inner bottom surface of the body 21 as the center and a diameter of d1, and each cuboid guide block 3 is deflected at an angle (that is, the cuboid guide block 3 deviates from the tangent of the positioning circle direction), preferably, the guide block forms an angle of 0 to 30° with the tangent line of the positioning circle.
  • the center line connecting the overflow holes 22 on both sides of the internal rotating flow stabilizer 2 is used as the positioning line b, and the line connecting the center of a rectangular parallelepiped flow guide block 3 and the center of the positioning circle a is the same as the positioning line b.
  • the corresponding internal rotation flow stabilizer and the front and rear porous diversion retaining walls are made.
  • the internal rotating flow stabilizer and porous diversion retaining wall are made of refractory materials.
  • the chemical composition of the refractory material is: MgO+Al 2 O 3 >90.0%, Fe 2 O 3 ⁇ 0.85%.
  • the compressive strength of the refractory material is ⁇ 50MPa and the volume density is ⁇ 2.75g/cm 3 to ensure that the structural functional parts of the tundish refractory material have good resistance to melting loss and service life, and meet the requirements for the number of continuous pouring furnaces in the steel plant.
  • an internally rotating flow stabilizer is installed below the long nozzle; front and rear porous diversion retaining walls are installed in the tundish.
  • the tundish maintenance, baking method and pouring method of the present invention are carried out using existing technologies.
  • the main inclusions in molten steel are alumina and calcium aluminate inclusions.
  • Table 1 lists the removal rates of calcium aluminate inclusions of multiple different size levels. It can be seen that the solution of the present invention can show higher removal rates for fine inclusions with an average particle size of 5-20 ⁇ m. Rate.
  • the difference lies in that the tundish of the present invention Based on the existing tundish, the package adds an internal rotating flow stabilizer and front and rear porous flow diversion retaining walls.
  • the metallurgical effect is better than that of the original tundish.
  • the removal rate of inclusions less than 20 ⁇ m is increased by more than 15% compared with the original tundish, even as high as 86.45%, which can be greatly improved. Reduce defects such as hydrogen-induced cracks and improve the quality of pipeline steel.

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Abstract

一种减少钢液中细微夹杂物的方法，与现有的中间包钢液中细微夹杂物的去除方法相比，采用本申请的方法夹杂物去除率可以提高15％以上，充分保证了获得高品质钢所需的钢液高纯净度。本发明还提供了实施上述方法的装置。

Description

一种减少钢液中细微夹杂物的方法及装置 技术领域
本发明涉及炼钢领域，尤其涉及一种减少钢液中细微夹杂物的方法及装置。
背景技术
钢液中的夹杂物是影响钢铁生产和应用的重要因素，钢中夹杂物的数量、尺寸和弥散程度对其质量均有较大影响，有效控制钢中非金属夹杂物是提高钢产品质量的关键。随着人们对钢洁净度要求越来越高以及对特定钢中性能要求的不断提升，20μm以下夹杂物的去除不断受到重视，特别是高洁净钢，如管线钢、汽车板钢和高牌号硅钢等。夹杂物控制与钢铁生产全流程各工序均相关，因此对钢液夹杂物的控制通常涉及到包括铁水预处理、冶炼、精炼、连铸等的钢铁生产全流程。
中国专利CN102676725A公开了一种控制钢中夹杂物的方法，包括以下步骤：1)喷吹Mg强脱硫进行铁水预处理；2)转炉出钢中加入萤石、活性石灰、铝块与合金进行预精炼；3)精炼过程中深脱硫，采用高碱度强还原性炉渣，控制钢液中S含量；LF处理过程满足[Als]在0.03～0.06％之间；4)对钢液进行真空处理，真空处理后进行Ca处理。通过上述方法使钢液中大尺寸夹杂物的数量大幅降低，满足了X70管线钢对夹杂物的苛刻要求。该技术采用优化冶炼工艺的方法来减少及控制钢中夹杂物，达到钢质量要求。由于冶炼及精炼处理周期较长，对提高生产效率带来一定的难度。
中国专利CN102816898A公开了一种提高顶渣改质的方法，用于降低顶渣的氧化性。在钢液真空处理时分二次加入复合脱氧剂，并吹氩调整钢液成分。在钢液处理后向钢包顶渣第三次加入复合脱氧剂。这样减少了IF钢中夹杂物数量，提高了汽车板的表面质量。
中国专利CN103014220A公开了一种改善钢液中非金属夹杂物的组 成和尺寸来提高钢液纯净度的方法。通过在LF精炼造白渣结束和RH真空处理结束时分别进行钙处理和软吹，控制非金属夹杂物的化学组成，以此来改变钢液中非金属夹杂物的熔点(1500℃～1650℃)、形状与大小。这样可在管线钢轧制及使用中避免产生裂纹。该方案是一种对非金属夹杂物进行改性的方法，可以提高钢产品的质量合格率。
中国专利CN102517419A公开了一种改善钢液洁净度、减少夹杂物含量的方法，其使钢中的非金属夹杂物进入塑性区，改变非金属夹杂物的形态，以此改善钢材的疲劳寿命。该文献公开的方法包括铁水处理、转炉冶炼、钢包精炼和连铸等工艺。尤其是在连铸工序中选用碱度为0.8～0.85的保护渣，结晶器采用电磁搅拌，主要控制的是电流强度与频率。该技术方案通过优化炼钢的全工序来进行夹杂物的控制，制造的钢材具有良好的质量。
通过对现有技术的分析，发明人发现炼钢全工序的各个步骤中都有减少及控制钢液中夹杂物的相应工艺。
1、从炼钢工艺上说，可以采用钢液成分控制，优化钢液的化学成分，增加有益元素，减少有害元素，来减少钢液中的夹杂物。
具体地，采用化学处理，多用钙、稀土处理，尽可能去除钢中的氧、硫基夹杂物等，来控制夹杂物的形态、改善铸态组织。
该炼钢工艺通过精炼、造渣改质或电磁搅拌等方式进行。
上述炼钢工艺采用的装备复杂、成本高、工艺较难精确控制，一般适用于减少钢中大型夹杂物的量。
2、连铸中间包被视为连接钢包和结晶器重要的冶金容器，能将具有预定流量和温度的钢液无污染、平稳地输运至结晶器。中间包内钢液夹杂物的控制是炼钢及连铸过程中最后的也是最为关键的一道工序，其中夹杂物的去除效果与机理备受关注。
在连铸工序中，较为广泛的去除钢液夹杂物的方法有气泡吸附法、结晶器内电磁搅拌法及过滤分离法。
1、在中间包内采用吹氩气泡去除法。如用中间包气幕挡墙、埋设透气砖、中间包密封吹氩等方法。但这些方法在实际操作过程中效果不稳定。具体地，尺寸细小的夹杂物去除效果不明显；气体吹入量受限制，有液面 波动；工艺成本高，安全性不佳。因此气泡法虽然操作容易，在生产中应用较广泛，且针对大尺寸夹杂物去除效果良好。但对于微小夹杂物的去除效果较弱，且可能带来新的气泡型夹杂，同时造成钢液的温度降低。
2、在结晶器内的电磁场中去除夹杂物的方法主要包括电磁搅拌与电磁制动。
电磁搅拌是在电磁场力的作用下，使结晶器内的钢液的流场发生改变，消除再循环区，延长钢液中夹杂物的滞留时间，提高夹杂物碰撞概率，促进夹杂物在结晶器中心碰撞和聚结、上浮，以去除夹杂物的工艺。
电磁制动是在磁场作用下产生与钢液流动方向相反的电磁力，降低结晶器内钢液的冲击深度，防止卷渣的工艺。此方法对夹杂物尺寸无特别限制。
电磁净化法(包括电磁搅拌和电磁制动)适用的工艺较为广泛，操作也相对灵活，但是需要的设备较复杂，且需要消耗大量电力资源。
3、过滤分离法，可以采用过滤装置，直接净化钢液中的夹杂物。但是过滤器的制作工艺复杂，材料昂贵，易堵塞，更换频率高，不能够适应高强度、长时间连铸作业，因此目前未见大规模实际应用。
高洁净钢(例如管线钢)中存在的夹杂物，特别是小于20μm的夹杂物，会直接导致钢的氢致裂纹等缺陷，极大地影响管线钢的性能。此外，钢中夹杂物对钢的塑性、韧性和疲劳强度等物理性能也有很大影响。因此除了在炼钢精炼过程中采取必要的措施外，还必须研究出在中间包内可以减少钢液中细微夹杂物的相对简便、有效、低成本的方法，从而提高钢产品的质量与市场竞争力。
发明内容
本发明的目的在于提供一种减少钢液中细微夹杂物的方法及装置，通过中间包设计，通过缓冲开浇钢液注流、控制湍流动能，来促进夹杂物碰撞、上浮，同时配合优化中间包中的钢液流场，延长钢液停留时间，促进尺寸小于20μm细微夹杂物碰撞凝聚长大、充分上浮，从而净化钢液。
为达到上述目的，本发明的第一方面提供了一种减少钢液中细微夹杂物的方法，包括：
a)在中间包的内底部对应长水口的下方设置内旋式稳流器，该内旋式稳流器具有上端开口的圆形壳体，所述内旋式稳流器的内部底面中央沿周向布置至少三个弧形挡块(沿弧形分布的长方体导流块)，所述内旋式稳流器的侧壁设有溢流孔；所述内旋式稳流器两侧的中间包内底部各自设置双层挡墙结构，所述双层挡墙结构包括依次设置的前多孔导流挡墙和后多孔导流挡墙；所述前多孔导流挡墙的上部设置、优选均匀设置多个上导流孔，后多孔导流挡墙的下部设置、优选均匀设置多个下导流孔；
b)开浇后钢液通过长水口冲击进入内旋式稳流器内，内旋式稳流器使开浇钢液发生转向，扰乱中间包内钢液的初始流场，形成旋流，旋流股中微米级夹杂物会向中心聚集，并在此处碰撞长大，达到一定尺寸的簇状夹杂物粒子团在斯托克斯浮力的作用下上浮到钢渣液面后被去除；
c)钢液从前多孔导流挡墙的上导流孔进入双层挡墙结构，非定常流动的钢液经过双层挡墙结构获得稳定流场，同时通过均匀分布在前多孔导流挡墙的上导流孔和后多孔导流挡墙的下导流孔改变钢液的运动轨迹；利用前、后多孔导流挡墙不同方向的上、下导流孔调整中间包内钢液流场方向，使细微夹杂物被顶渣吸附脱除。
本发明的第二方面提供了一种用于上述方法的装置，包括：
中间包，
设置于所述中间包内的内旋式稳流器，以及
位于内旋式稳流器两侧的双层挡墙结构；其中，
所述内旋式稳流器设置于中间包内底部中对应长水口的下方，包括：本体，其为上端开口的圆形壳体，本体的两侧壁设有溢流孔，优选地，溢流孔的轴线与水平方向成一角度；本体内底面设置有周向排列的四块长方体导流块，各导流块的中心均分布在一个以本体内底面中心为圆心的定位圆上，且，各导流块均偏转一角度；优选地，所述导流块与定位圆切线成0～30°角；
所述双层挡墙结构设置于所述内旋式稳流器两侧的中间包的中注区，在内旋式稳流器两侧分别设置双层挡墙结构，所述双层挡墙结构由前多孔导流挡墙和后多孔导流挡墙构成，前多孔导流挡墙的上部设有上导流孔， 后多孔导流挡墙的下部设有下导流孔；优选地，前多孔导流挡墙和/或后多孔导流挡墙的底部也设有导流孔。
优选地，所述内旋式稳流器的外径与中间包内底部的宽度相同。
优选地，所述前多孔导流挡墙的上导流孔和/或后多孔导流挡墙的下导流孔的轴线与水平成20～40°角，优选地，上导流孔和/或下导流孔的直径为40～60mm。
优选地，所述前多孔导流挡墙与后多孔导流挡墙之间的距离为300～400mm。
优选地，所述前多孔导流挡墙距长水口中心线1500～1800mm。
优选地，以所述内旋式稳流器两侧的溢流孔的中心连线作为定位线，一导流块的中心与定位圆中心的连线与该定位线的夹角为θ1，θ1＝65～70°；优选地，各导流块的中心线相互垂直。
优选地，所述内旋稳流器及前、后多孔导流挡墙均由耐火材料制成，所述耐火材料的化学成分重量百分比为：MgO+Al2O3>90.0％，Fe2O3<0.85％；所述耐火材料的耐压强度≥50MPa，体积密度≥2.75g/cm3。
本发明还提供一种内旋式稳流器，用于实施上述方法，该内旋式稳流器包括：本体，其为上端开口的圆形壳体，本体两侧壁对称各设有溢流孔，优选地，溢流孔轴线与水平方向成一角度(该轴线偏离水平方向，便于内旋式稳流器内残余的钢液流出)；本体内底面沿周向设置有四块长方体导流块，各导流块的中心均分布在一个以本体内底面中心为圆心的定位圆的圆周上，且各导流块均偏转一角度(即导流块的方向偏离定位圆在该导流块中心处的切线方向)，优选地，所述导流块与定位圆的切线成0～30°角。
优选地，以所述内旋式稳流器两侧的溢流孔的中心连线作为定位线，一导流块的中心与定位圆中心的连线与该定位线的夹角为θ1，θ1＝65～70°；优选地，各导流块的中心线相互垂直。
优选地，所述导流块长160～170mm，宽40～50mm，高30～40mm。
开浇后钢液通过长水口首先冲击进入中间包内底部的内旋式稳流器，由于在内旋式稳流器的底部沿周向布置了导流块，开浇钢流冲击内旋式稳流器后在稳流器空腔内发生转向，扰乱中间包内初始流场并形成旋流，在 增加钢液停留时间的同时增加了钢液中夹杂物的运动距离和碰撞几率。
在导流块内侧所构成的内圆中，从长水口流出的钢液速度较快，会在该区域内形成高压区；钢液从内圆向外流出时涌入相邻导流块之间的通道，由内圆向外圆过渡的通道逐渐缩窄，少部分钢液加速通过通道流出外圆区域，但大部分钢液流股受到阻碍形成向上的涡流以及随之形成的二次涡流；这种强涡流的中心压强较低，使流股中的细微夹杂物向低压中心聚集，并在此处碰撞长大，达到一定尺寸的簇状夹杂物粒子团会在斯托克斯浮力的作用下上浮到钢渣液面被去除。并且内旋式稳流器内圆和外圆区域内形成的压强变化，可以有效地对流体进行破碎，防止夹杂物粒子在中间包底部随流体运动进入铸坯影响产品质量。这一步就能大幅提高夹杂物在中间包内的去除效率，从而有助于提高钢液的洁净度，进而提高形成的钢材的洁净度。接下来，包含夹杂物的钢液从前挡墙的导流孔进入双层挡墙结构，双层挡墙相当于一个钢液流动的诱导装置，非定常流动的钢液经过双层挡墙获得稳定流场，同时通过均匀分布在挡墙上的导流孔改变钢液的运动轨迹，防止出现短路流。利用前后挡墙不同方向的导流孔，调整包内钢液流场方向，方便细微夹杂物被顶渣吸附脱除。多孔挡墙使分配到各个浸入式水口的钢液分布变得更加均匀，增加了钢液从钢包长水口到中间包浸入式水口之间的平均停留时间，利于细微夹杂物成分上浮。这样在经过一系列精炼工艺控制减少夹杂物后，钢液在中间包内再次去除细微夹杂物，实现钢液的高纯净化。
本发明的方法利用改进的连铸中间包进行连铸，具有如下有益效果：
1、在中间包长水口下方设置内旋式稳流器，一方面，内旋式稳流器可以防止钢液喷溅，另一方面，由于在内旋式稳流器底部周向(环绕内旋式稳流器的轴线方向)间隔布置导流块，使钢液产生旋流带，钢液发生有规律地湍流碰撞，可以延长钢液停留时间，利于钢液中微米级细微夹杂物向中心聚集碰撞长大并被去除。
所述内旋式稳流器的作用如下：
(1)有效抑制中注区钢液湍动能，稳定钢液流场，降低注流区液面波动，防止卷渣或者裸露，造成二次氧化；
(2)内旋式稳流器内部设置与定位圆切线方向具有一定偏转角度的 长方体导流块，使中间包内长水口下方中注区的钢液形成旋流，产生的离心力促进微米级夹杂物向中心聚集、长大，利于上浮去除；
(3)中间包中注区钢液的旋流流动，利于钢液混匀，延长流动路径，增加钢液和夹杂物在注流区的停留时间，利于夹杂物的去除。
2、在中间包中注区两边设置双层导流挡墙，即前、后多孔导流挡墙，不仅能控制钢液的流动路径，而且能阻止夹杂物进入到中间包注流区的水口区域，从而减少细微夹杂物，净化钢液。
所述前、后多孔导流挡墙促进夹杂物排除的机理如下：
(1)该双层挡墙结构可以有效改变中间包中的钢液流场，减轻包底冲蚀，消除短路流，将强湍流限制在冲击区内，使中间包水口附近的钢液流动趋于平稳，流线加长；
(2)在前多孔导流挡墙的上部和后多孔导流挡墙的下部分别设置导流孔，对钢液起到分流作用；
(3)能延长钢液平均停留时间，有利于夹杂物充分上浮。
3、内旋稳流器及前、后多孔导流挡墙均由耐火材料制成，，该耐火材料以质量百分比计含有MgO+Al2O3>90.0％，Fe2O3<0.85％，并且耐火材料的耐压强度≥50MPa，体积密度≥2.75g/cm3，可以满足钢厂所需要的连浇炉数寿命要求。
本发明的有益效果：
钢液不纯净会导致连铸坯内部质量不佳，对钢的使用性能和范围产生影响。钢液在进入结晶器之前最后需要经过的具有耐火性能的容器为中间包，钢液的清洁程度(例如，其中夹杂物的大小及含量)与中间包内钢液的运动方式以及耐火材料的类型密切相关。为了去除钢液中的细微夹杂物，在连铸中间包内设计了各种控流装置以促进夹杂物的上浮去除。但是直径小于20μm的夹杂物在连铸中间包中很难上浮去除，因此去除20μm以下的细微夹杂物已日益成为限制钢材清洁度的一个难点。
本发明提供了中间包内设置内旋式稳流器+双层导流挡墙的方案，用以减少中间包内钢液中的细微夹杂物。采用本发明的装置能有效抑制中注区钢液的湍动能，形成旋流使微米级夹杂物向中心聚集、长大，利于细微夹杂物上浮去除；同时，优化钢液流动路径，防止短路流动，利于钢液混 匀，延长钢液和夹杂物的分离与停留时间，使钢液中小于20μm的细微夹杂物去除率与现有技术相比提高15％以上，甚至可以高达86.45％。采用本发明的装置进行连铸，能充分保证形成高品质钢所需的钢液高纯净度，可大大减少钢产品的氢致裂纹等缺陷，提高高洁净钢如管线钢的质量。
附图说明
图1为本发明中装置的结构示意图；
图2为本发明中内旋式稳流器的俯视图；
图3为本发明中内旋式稳流器的正视图；
图4为本发明中前多孔导流挡墙的正视图；
图5为本发明中前多孔导流挡墙的侧视图；
图6为本发明中后多孔导流挡墙的正视图；
图7为本发明中后多孔导流挡墙的侧视图；
图8为本发明中装置的立体图。
附图标记：
1-中间包，100-长水口，2-内旋式稳流器，21-本体，22-溢流孔，3-长方体导流块，4-前多孔导流挡墙，41-上导流孔，5-后多孔导流挡墙，51-下导流孔。
具体实施方式
下面参见图1～图8对本发明的方法和装置进行具体说明。
如图所示，本发明所述的减少钢液中细微夹杂物的方法包括：
a)a)在中间包1内底部中对应长水口100的下方设置一内旋式稳流器2，该内旋式稳流器2具有上端开口的圆形壳体，其内部底面沿周向间隔布置至少三个弧形挡块3(即长方体导流块)，所述周向环绕所述壳体的轴线方向，内旋式稳流器2的侧壁设有溢流孔22，优选地，溢流孔22轴线与水平方向成一角度；所述内旋式稳流器2两侧的中间包1内底部分别各依次设置前多孔导流挡墙4和后多孔导流挡墙5，形成双层挡墙结构；所述前多孔导流挡墙4的上部及所述后多孔导流挡墙5的下部分别均匀设置多个上导流孔41和下导流孔51；
b)开浇后钢液通过长水口100冲击进入内旋式稳流器2内，内旋式稳流器2使开浇钢液发生转向，扰乱中间包1内的钢液初始流场并形成旋流，旋流股中微米级夹杂物会向中心聚集，并在此处碰撞长大，达到一定尺寸的簇状夹杂物粒子团会在斯托克斯浮力的作用下上浮到钢渣液面后被去除；
c)钢液从前多孔导流挡墙4的上导流孔41进入双层挡墙结构，非定常流动的钢液经过双层挡墙结构获得稳定流场，同时通过均匀分布在前、后多孔导流挡墙4、5的上、下导流孔41、51改变钢液的运动轨迹；利用前、后多孔导流挡墙4、5不同方向的上、下导流孔41、51调整中间包1内钢液流场方向，使细微夹杂物被顶渣吸附脱除。
步骤b)中，无需指明钢液在内旋式稳流器内运动的过程中产生的夹杂物粒子团的尺寸，只要夹杂物粒子团能上浮至钢渣液面即可被有效去除。
此外，如图1和8所示，本发明的用于所述减少钢液中细微夹杂物的方法的装置包括：中间包1，设置于中间包1内的内旋式稳流器2及位于内旋式稳流器2两侧的双层挡墙结构；
所述内旋式稳流器2设置于中间包1内底部中对应长水口100的下方，其包括：本体21，其为上端开口的圆形壳体，本体两侧壁设有溢流孔22，优选地，溢流孔22的轴线与水平方向成一角度；本体21内底面设置有沿周向(环绕本体的轴线方向)间隔排列的四个长方体导流块3，各导流块3的中心均分布在一个以本体21内底面中心为圆心的定位圆a上，且，各导流块3均偏转一角度(即导流块的方向偏离定位圆的切线方向)，优选地，所述导流块3与定位圆a的切线成0～30°角；
所述双层挡墙结构设置于中间包1的中注区，在内旋式稳流器两侧分别设置双层挡墙结构，该双层挡墙结构包括前、后多孔导流挡墙4、5。前多孔导流挡墙4的上部设有上导流孔41，后多孔导流挡墙5的下部设有下导流孔51。具体结构参见图4-7。图5和7中的箭头方向为钢液流动方向。优选地，前多孔导流挡墙和/或后多孔导流挡墙的底部也设有导流孔。
优选地，所述内旋式稳流器2的外径与中间包1内底部宽度相同。参 考图8，内旋式稳流器2的外径和中间包1底部宽度相同，这样内旋式稳流器2能恰好置于中间包1内。
优选地，所述前、后多孔导流挡墙4、5的上导流孔41和/或下导流孔51的轴线与水平成20～40°角，优选地，上导流孔和/或下导流孔的直径为40～60mm。
优选地，所述前多孔导流挡墙4与后多孔导流挡墙5的间距为300～400mm。
优选地，所述前多孔导流挡墙4距长水口100中心线1500～1800mm。
优选地，所述内旋式稳流器2两侧的溢流孔22的中心连线作为定位线，一导流块3的中心与定位圆中心的连线与该定位线的夹角为θ1，θ1＝65～70°；优选地，各导流块3的中心线相互垂直。
优选地，所述内旋稳流器及前、后多孔导流挡墙均由耐火材料制成，所述耐火材料的化学成分重量百分比为：MgO+Al2O3>90.0％，Fe2O3<0.85％，材料的耐压强度≥50MPa，体积密度≥2.75g/cm3。本发明选用的耐火材料为常用的MgO-Al2O3基耐火材料，具有良好的耐高温、耐热震和抗熔渣侵蚀性能。Fe2O3是材料中的杂质，含量越低越好。耐火材料的耐压强度通常在50MPa以上，例如是50-80MPa。也可根据实际需要选择强度为50-70MPa或50-60MPa的材料。耐火材料体积密度通常在2.75g/cm3以上，例如是2.75-3.00g/cm3。
图2和图3示出本发明用于减少钢液中细微夹杂物的方法的内旋式稳流器2，包括：本体21，其为上端开口的圆形壳体，本体21两侧壁对称各设有一溢流孔22；本体21内底面设置有环形排列(即沿周向排列，所述周向环绕所述本体的轴线方向)的四块长方体导流块3，各长方体导流块3的中心均分布在一个以本体21内底面中心为圆心、直径为d1的定位圆a的圆周上，且，各长方体导流块3均偏转一角度(即长方体导流块3偏离定位圆的切线方向)，优选地，所述导流块与定位圆切线成0～30°角。
优选地，以所述内旋式稳流器2两侧溢流孔22的中心连线作为定位线b，一长方体导流块3的中心与定位圆a中心的连线与该定位线b的夹角为θ1，θ1＝65～70°；优选地，各长方体导流块3的中心线相互垂直。
优选地，所述长方体导流块3长L1＝160～170mm，宽L2＝40～50mm，高30～40mm。
实施例
按中间包容积大小制做相应的内旋式稳流器以及前、后多孔导流挡墙。内旋式稳流器及多孔导流挡墙均由耐火材料制成。以质量百分比计，耐火材料的化学组成为：MgO+Al2O3>90.0％，Fe2O3<0.85％。并且，耐火材料的耐压强度≥50MPa，体积密度≥2.75g/cm3，以保证中间包耐火材料结构功能件具有良好抗熔损性能及使用寿命，满足钢厂连浇炉数要求。
按图1的方式在长水口下方设置内旋式稳流器；在中间包内设置前、后多孔导流挡墙。本发明的中间***护、烘烤方法与开浇方式采用现有技术进行。
表1钢液中各级别夹杂物的去除率
将采用本发明的方法处理后的钢水取出，放在电镜下观察，在视场中取10个以上不同位置，拍摄电镜照片。根据SEM图像得到氧化铝和钙铝酸盐的平均粒度。
钢液中的主要夹杂物为氧化铝和钙铝酸盐夹杂物。表1中列出了对多个不同尺寸级别的钙铝酸盐夹杂物的去除率，可看出，本发明的方案对于平均粒度为5-20μm的细微夹杂物均能表现出较高的去除率。
表1中的现有中间包与本发明中间包相比，区别在于，本发明的中间 包在现有中间包的基础上增加了内旋式稳流器以及前、后多孔导流挡墙。参见表1，通过本发明实际应用及铸坯钢样夹杂物分析，比原来中间包冶金效果好，小于20μm的夹杂物比原中间包去除率增加了15％以上，甚至高达86.45％，可大大减少氢致裂纹等缺陷，提高管线钢质量。
以上所述仅为本发明的较佳实例，并不用于限制本发明。凡在本发明的精神及原则、方法之内，所作的任何修改、替换、改进等，均包含在本发明的保护范围之内。

Claims (11)

  1. 一种减少钢液中细微夹杂物的方法，其特征是，所述方法包括以下步骤：
    a)在中间包的内底部对应长水口的下方设置内旋式稳流器，所述内旋式稳流器具有上端开口的圆形壳体，所述内旋式稳流器的内部底面中央沿周向布置至少三个弧形挡块，所述内旋式稳流器的侧壁设有溢流孔；所述内旋式稳流器两侧的中间包内底部各自设置双层挡墙结构，所述双层挡墙结构包括依次设置的前多孔导流挡墙和后多孔导流挡墙；所述前多孔导流挡墙的上部设置多个上导流孔，所述后多孔导流挡墙的下部设置多个下导流孔；
    b)开浇后钢液通过长水口冲击进入内旋式稳流器内，所述内旋式稳流器使开浇钢液发生转向，扰乱所述中间包内钢液的初始流场，形成旋流，旋流股中微米级夹杂物会向中心聚集，并在此处碰撞长大，达到一定尺寸的簇状夹杂物粒子团在斯托克斯浮力的作用下上浮到钢渣液面后被去除；
    c)钢液从前多孔导流挡墙的上导流孔进入双层挡墙结构，非定常流动的钢液经过双层挡墙结构获得稳定流场，同时通过均匀分布在前多孔导流挡墙的上导流孔和后多孔导流挡墙的下导流孔改变钢液的运动轨迹；利用前、后多孔导流挡墙不同方向的上、下导流孔调整中间包内钢液流场方向，使细微夹杂物被顶渣吸附脱除。
  2. 一种用于如权利要求1所述的方法的装置，所述装置包括：中间包，设置于所述中间包内的内旋式稳流器以及位于所述内旋式稳流器两侧的双层挡墙结构；其中，
    所述内旋式稳流器设置于中间包内底部，对应于长水口的下方，包括：本体，其为上端开口的圆形壳体，所述本体的两侧壁设有溢流孔，优选地，溢流孔的轴线与水平方向成一角度；所述本体内底面设置有周向排列的四块长方体导流块，各导流块的中心均分布在一个以本体内底面中心为圆心的定位圆上，且，各导流块均偏转一角度，优选地，所述导流块与定位圆切线成0～30°角；
    所述双层挡墙结构设置在所述中间包的中注区，在所述内旋式稳 流器两侧分别设有双层挡墙结构，所述双层挡墙结构由前多孔导流挡墙和后多孔导流挡墙构成，所述前多孔导流挡墙的上部设有上导流孔，所述后多孔导流挡墙的下部设有下导流孔；优选地，所述前多孔导流挡墙和/或所述后多孔导流挡墙的底部也设有导流孔。
  3. 如权利要求2所述的装置，其特征在于，所述内旋式稳流器的外径为600～700mm，优选地，所述内旋式稳流器的外径与中间包内底部的宽度相同。
  4. 如权利要求2所述的装置，其特征在于，所述前多孔导流挡墙的上导流孔和/或后多孔导流挡墙的下导流孔的轴线与水平方向成20～40°角，优选地，上导流孔和/或下导流孔的直径为40～60mm。
  5. 如权利要求2或4所述的装置，其特征在于，所述前多孔导流挡墙与后多孔导流挡墙之间的距离为300～400mm。
  6. 如权利要求2或4或5所述的装置，其特征在于，所述前多孔导流挡墙距长水口的中心线1500～1800mm。
  7. 如权利要求2或3所述的装置，其特征在于，以所述内旋式稳流器两侧溢流孔的中心连线作为定位线，一导流块的中心与定位圆中心的连线与所述定位线的夹角为θ1，θ1＝65～70°；优选地，各导流块的中心线相互垂直。
  8. 如权利要求2～7中任何一项所述的装置，其特征在于，所述内旋式稳流器、前多孔导流挡墙和后多孔导流挡墙由耐火材料制成，所述耐火材料的化学成分以重量百分比计为：MgO+Al2O3>90.0％，Fe2O3<0.85％，所述耐火材料的耐压强度≥50MPa，体积密度≥2.75g/cm3。
  9. 一种内旋式稳流器，其特征在于，所述内旋式稳流器包括：本体，其为上端开口的圆形壳体，所述本体两侧壁对称设有溢流孔，优选地，溢流孔的轴线与水平方向成一角度；所述本体内底面沿周向设置有四块长方体导流块，各导流块的中心均分布在一个以本体内底面中心为圆心的定位圆的圆周上，且各导流块均偏转一角度，优选地，所述导流块与所述定位圆的切线成0～30°角。
  10. 如权利要求9所述的内旋式稳流器，其特征在于，以所述内旋式稳流 器两侧的溢流孔的中心连线作为定位线，一导流块的中心与所述定位圆中心的连线与所述定位线的夹角为θ1，θ1＝65～70°；优选地，各导流块的中心线相互垂直。
  11. 如权利要求9或10所述的内旋式稳流器，其特征在于，所述导流块长160～170mm，宽40～50mm，高30～40mm。
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CN103240406A (zh) * 2013-04-28 2013-08-14 首钢总公司 连铸中间包及连铸中间包浇铸控制方法
CN103990786A (zh) * 2014-05-16 2014-08-20 莱芜钢铁集团有限公司 一种用于去除双流板坯连铸机中间包内钢液夹杂物的装置及方法
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CN209754003U (zh) * 2018-12-28 2019-12-10 南京钢铁股份有限公司 一种连铸用中间包
CN110270679A (zh) * 2019-07-12 2019-09-24 南京钢铁股份有限公司 一种大方坯四流中间包
CN110653366A (zh) * 2019-11-18 2020-01-07 武汉科技大学 连铸中间包带缓冲球旋流式湍流抑制器

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