A method for reducing the amount of residual molten steel in a ladle by adding a resistance plug

Abstract

The application relates to the technical field of metallurgical steelmaking, in particular to a method for reducing residual molten steel in a ladle by adding a resistance plug. The method comprises the following steps: preparing a composite resistance plug with a high-density iron-based inner core, a refractory functional layer and an asymmetric guide vane; when the residual molten steel height of the ladle is 3 to 5 times the inner diameter of the nozzle, the resistance plug is vertically dropped onto the nozzle by an automatic device; the resistance plug sinks and suspends under the action of gravity, and the asymmetric guide vane generates a tangential resistance to the molten steel flowing to the nozzle. The application can destroy the dynamic conditions of the funnel-shaped vortex by physical intervention, divide the macroscopic vortex into small turbulent groups, effectively inhibit the occurrence of slag entrapment, delay the critical liquid level of the vortex, significantly reduce the amount of residual molten steel at the bottom of the ladle, and improve the utilization rate of metal resources.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical steelmaking technology, specifically a method for reducing residual molten steel in a ladle by adding a stopcock. Background Technology

[0002] In the continuous casting process of metallurgical production, as the molten steel level continues to drop towards the end of the pouring stage, a violent funnel-shaped vortex is easily generated above the nozzle due to factors such as the Coriolis effect and the geometry of the vessel. This vortex can entrain slag from the surface of the molten steel into the nozzle, thus affecting the purity of the molten steel and potentially causing defects in the cast billet. To ensure the quality of the molten steel, operators usually close the nozzle prematurely when a slag entrainment signal is detected or the critical liquid level is reached. This results in a large amount of molten steel remaining at the bottom of the ladle, known as "cast residue," which reduces metal yield and increases production costs. Therefore, how to suppress vortex generation and reduce the vortex height through physical means to reduce cast residue has become a key research direction for improving steelmaking efficiency.

[0003] Patent CN121061136A discloses a vortex-blocking plug for steel ladle nozzles and its usage method. The plug is composed of a solid counterweight material and a coating layer, and its side surface has four symmetrically distributed arc-shaped grooves. This technology aims to reduce vortex velocity and decrease penetration height by dividing individual vortices through the grooves. However, in actual operating conditions, due to the relatively simple surface groove structure of the plug, its flexibility in adjusting the flow field when dealing with steel grades with different flow velocities or large viscosity differences has room for improvement, and the stability of the plug under the intense scouring of high-temperature molten steel still needs further enhancement.

[0004] Patent CN111266564B discloses a vortex-blocking device for limiting vortex generation in a ladle and its application. This device, made of refractory material, is installed above the nozzle and utilizes fluid dynamics principles to change the direction of fluid movement near the outlet. While this solution has some effect in suppressing vortex generation, the positioning relationship between the device and the nozzle is relatively fixed. Maintaining precise alignment between the vortex-blocking device and the center of the flow field under dynamic conditions such as frequent ladle lifting and bottom argon blowing presents a challenge, resulting in a less than ideal effect in further reducing excess molten steel. Summary of the Invention

[0005] This invention provides a method for reducing residual molten steel in a ladle by adding a swirl stopper. The aim is to use a swirl stopper with a specific structure to perform asymmetric physical intervention on the flow field at the end of the ladle pouring, thereby disrupting the dynamic conditions for the formation of funnel-shaped vortices and reducing the slag swirling height.

[0006] In a first aspect, the present invention provides a method for reducing excess molten steel in a ladle by adding a stopcock, comprising the following steps: S10: Prepare a composite swirl plug with multi-stage flow channels; the composite swirl plug includes an inner core, a fire-resistant functional layer covering the outer periphery of the inner core, and asymmetric guide vanes disposed on the surface of the fire-resistant functional layer; the inner core is made of a high-density counterweight material, and the density of the inner core is 6.5 to 7.8 grams per cubic centimeter. S20: When the ladle is poured to a height of 3 to 5 times the inner diameter of the nozzle, the composite rotary stopper is vertically placed above the ladle nozzle using a dispensing device. S30: The composite vortex plug sinks under gravity in the molten steel and is suspended above the nozzle. The asymmetric guide vanes generate tangential resistance to the molten steel flowing towards the nozzle, dividing the single macroscopic vortex into multiple tiny turbulent clusters until the casting is completed.

[0007] According to the present invention, by setting a composite vortex-blocking plug with a high-density inner core, the balance of gravity and buoyancy is used to precisely position it above the nozzle at the end of the molten steel flow. As the molten steel flows through, the asymmetric guide vanes change the radial velocity vector distribution of the fluid. By physically blocking and changing the momentum transfer direction, they suppress the angular momentum conservation process of converging vortices, causing the low-pressure zone, which originally tended to be centrally continuous, to be filled with discrete turbulent structures. This delays the occurrence of slag entrainment and reduces the amount of residual molten steel at the bottom of the ladle.

[0008] In some embodiments, the method for preparing the inner core in step S10 includes: mixing waste steel scrap, reduced iron powder and binder in a mass ratio of 100:15 to 25:5 to 8, pressing the mixture under a pressure of 200 to 300 MPa, and performing reduction sintering at 1000 to 1100 degrees Celsius.

[0009] In some embodiments, in step S10, the raw materials of the refractory functional layer include, by weight: 45 to 60 parts of fused white corundum particles, 20 to 35 parts of tabular corundum fine powder, 5 to 12 parts of activated alumina micro powder, 3 to 8 parts of spinel powder, 4 to 9 parts of pure calcium aluminate cement, and 1 to 3 parts of heat-resistant stainless steel fiber.

[0010] In some embodiments, the preparation process of the refractory functional layer includes: mixing the above raw materials evenly, adding 4 to 6% water by weight of the total raw materials and stirring, pouring it into a mold on the outer periphery of the inner core, allowing it to cure naturally for 24 to 48 hours, and then baking it at 110 to 200 degrees Celsius for 12 to 24 hours.

[0011] In some embodiments, the asymmetric guide vanes are spirally distributed on the outer surface of the fire-resistant functional layer, and the helix angle of the vanes gradually decreases from 30 degrees to 15 degrees from the top to the bottom; the number of asymmetric guide vanes is 3 to 6, and the arc length central angle between adjacent vanes is not equally distributed, with the difference between adjacent central angles being 5 to 15 degrees.

[0012] In some embodiments, the radial outer edge of the asymmetric guide vane is provided with a serrated staggered structure, the depth of the serrations being 10 to 20 mm and the tooth pitch being 15 to 30 mm.

[0013] In some embodiments, the overall density of the composite throttle plug is adjusted to 4.5 to 5.5 grams per cubic centimeter, which is achieved by adjusting the volume ratio of the inner core to the refractory functional layer.

[0014] In some embodiments, in step S20, the dispensing device includes an infrared liquid level detector and an automatic dispensing slide rail; the infrared liquid level detector monitors the liquid level in the ladle in real time, and when the liquid level reaches a preset range of 300 to 500 mm, it triggers the automatic dispensing slide rail to send in the composite rotary plug.

[0015] In some embodiments, the bottom of the composite throttle plug is provided with a concave hemispherical cavity, the diameter of which is 0.4 to 0.6 times the maximum diameter of the composite throttle plug.

[0016] In some embodiments, the surface of the composite stopcock is coated with an anti-oxidation coating, the thickness of which is 0.5 to 1.5 mm, and the coating comprises silicon carbide powder, graphite powder, and phosphate binder.

[0017] Secondly, the present invention provides a composite slewing plug for the above-described method, characterized in that the composite slewing plug comprises: The centrally symmetrical high-density inner core is made of sintered iron-based alloy. An aluminum-magnesium refractory layer covering the outside of the inner core; The variable cross-section guide ribs are disposed on the surface of the aluminum-magnesium refractory layer, and the cross-sectional area of ​​the variable cross-section guide ribs gradually increases from top to bottom.

[0018] According to the present invention, the composite vortex deflector employs a composite structure of an inner core and an outer layer. The inner core provides sufficient gravity to overcome the buoyancy of the molten steel and the rising airflow at the nozzle (if argon is blown), while the outer layer provides resistance to refractory erosion. The variable cross-section guide ribs generate a local pressure gradient by altering the flow cross-section of the fluid. The direction of this pressure gradient is opposite to the direction of the centripetal force forming the vortex, thus blocking the formation path of the vortex core through mechanical intervention in fluid dynamics.

[0019] In some embodiments, the variable cross-section guide ribs are made of the same material as the aluminum-magnesium refractory layer and are cast using an integral mold.

[0020] In some embodiments, the surface roughness Ra of the variable cross-section guide rib is 12.5 to 25 micrometers, achieved by pre-applying a roughening layer on the inner wall of the mold.

[0021] In some embodiments, the high-density inner core is spindle-shaped, with its maximum radial dimension located at the lower third of the height direction.

[0022] In some embodiments, the aluminosilicate refractory layer further contains 2 to 5% by mass of zirconium oxide micropowder, the zirconium oxide micropowder having an average particle size of 1 to 5 micrometers.

[0023] In some embodiments, the top of the composite stopcock is provided with a hook or ring, which is made of alloy steel with a melting point of 1400 to 1500 degrees Celsius.

[0024] In some embodiments, the ratio of the total height of the composite throttle plug to its maximum diameter is 1.2 to 1.8.

[0025] In some embodiments, the edges of the asymmetric guide vanes are embedded with ceramic wear-resistant strips, the ceramic wear-resistant strips being made of silicon nitride or boron carbide.

[0026] In some embodiments, the inner wall of the hemispherical cavity of the composite throttle plug is provided with radially distributed raised ribs, the number of which is 8 to 12.

[0027] In some embodiments, in step S10, the adhesive is a phenolic resin or an aqueous solution of polyvinyl alcohol.

[0028] In some implementations, the delivery speed in step S20 is controlled at 2 to 5 meters per second.

[0029] This invention, through the aforementioned technical solution and the physical design of a composite vortex-blocking plug, alters the flow field vector distribution above the nozzle at the end of the ladle's operation. The high-density inner core, combined with a refractory layer of specific density, allows the plug to remain stably suspended in the molten steel below the steel-slag interface. Asymmetrically distributed guide vanes with variable cross-sections forcibly alter the fluid's circulation trajectory as the molten steel flows downwards, increasing the radial velocity of fluid particles and reducing their tangential velocity, thus disrupting the angular momentum equilibrium environment required for vortex development. The serrated, staggered structure further breaks down potentially large vortices into smaller, fragmented turbulent flows, preventing gas and slag from entering the nozzle through the interconnected vortex core. This purely physical intervention, without altering the ladle structure or adding complex external power equipment, achieves control over the outflow behavior of molten steel through precise induction of fluid dynamics, significantly lowering the critical vortex initiation level and thus reducing the amount of molten steel remaining at the bottom of the ladle.

[0030] Specifically, in the preparation of the composite swirl stopper, a precisely controlled density distribution was achieved by controlling the ratio of scrap steel chips to reduced iron powder in the inner core and sintering under specific pressure and temperature. This density distribution ensures that the center of mass of the swirl stopper is located below the geometric center after entering the molten steel, providing self-correcting stability under flow field disturbances. The refractory functional layer uses a composite ratio of fused white corundum and tabular corundum, and incorporates spinel powder and heat-resistant stainless steel fibers. Through fine-tuning of the chemical composition and physical reinforcement, the stopper maintains its geometric integrity when subjected to the intense scouring of molten steel at temperatures of 1550 to 1650 degrees Celsius. In particular, the edges of the asymmetric guide vanes are not rapidly melted away, thus continuously playing a flow field regulating role throughout the final stage of casting.

[0031] During the dispensing phase, the linkage between the infrared liquid level detector and the automatic dispensing mechanism ensures that the timing of the vortex deflector entering the flow field is precisely at the early stage of vortex development. After the vortex deflector enters the molten steel, its hemispherical cavity structure at the bottom captures a portion of the molten steel during its descent, increasing its downward inertia and subsequently forming a stable hydrodynamic support in the recirculation zone above the nozzle. The asymmetrically distributed blades generate unbalanced lateral forces in the fluid during its flow, inducing random disturbances in the flow field and effectively suppressing the growth of periodic vortices.

[0032] Through the aforementioned series of specific technical means, this invention constructs a synergistic swirl-blocking system from multiple dimensions, including materials science, fluid mechanics, and mechanical structure design. This system directly intervenes in the evacuation process of molten steel from the ladle by altering fluid boundary conditions and internal momentum exchange mechanisms, minimizing the proportion of residual molten steel that would otherwise be wasted to avoid slag entrapment, thereby improving the utilization efficiency of metal resources.

[0033] The parameter ranges involved in this invention, such as the core density of 6.5 to 7.8 g / cm³, the helix angle gradually decreasing from 30 degrees to 15 degrees, and the amount of each raw material component added, are all optimized ranges determined based on extensive fluid simulation and hot-state experiments. This precise combination of values ​​ensures that the swirl-blocking plug can accurately perform its physical swirl-blocking function in the high-temperature, high-pressure scouring and complex and variable ladle flow field environment. For example, if the core density is below 6.5 g / cm³, the plug may float in the slag layer due to excessive buoyancy and fail to penetrate the core flow field above the nozzle; if it is above 7.8 g / cm³, it may sink too quickly and block the nozzle. The addition of 3 to 8 parts of spinel powder in the refractory material utilizes its micro-expansion effect at high temperatures to offset the shrinkage caused by cement dehydration, maintaining the dimensional accuracy of the blade structure.

[0034] Furthermore, the design of the asymmetric guide vanes with an adjacent center angle difference of 5 to 15 degrees breaks the axisymmetric balance of the flow field through the asymmetry of the physical structure. This is an effective means of suppressing resonance and the generation of regular vortices in fluid dynamics. The serrated staggered structure increases the local drag coefficient and induces fine Karman vortex streets at the blade edges. These tiny vortices cancel each other out with the energy of the main vortex, further reducing the penetrating energy of the vortex.

[0035] In summary, this invention provides a highly efficient, stable, and easily industrially implementable method for reducing residual molten steel through a systematic design of the rotary valve, from its microscopic material composition to its macroscopic structural morphology. This provides a practical and feasible technical solution for energy conservation and consumption reduction in metallurgical processes.

[0036] In some embodiments, step S10, the method for preparing the inner core further includes: subjecting the sintered inner core to surface sandblasting treatment to increase the mechanical interlocking force between it and the refractory functional layer.

[0037] In some embodiments, the refractory functional layer is further provided with a non-ferrous metal tracer comprising 0.1 to 0.3% of the total mass. The non-ferrous metal tracer is copper powder or nickel powder, which is used to provide timely feedback through steel composition monitoring when abnormal melting occurs in the stopcock.

[0038] In some embodiments, the spiral direction of the asymmetric guide vanes is opposite to the direction of the molten steel circulation caused by argon blowing at the bottom of the ladle.

[0039] In some embodiments, the phosphate binder in the anti-oxidation coating applied to the surface of the composite stopcock is aluminum dihydrogen phosphate, with a mass fraction of 15 to 25%.

[0040] In some embodiments, in step S30, the opening of the sprue slide plate is adjusted in conjunction with the suspension height of the rotary valve to maintain the molten steel flow rate at 3 to 5 tons per minute.

[0041] In some embodiments, the composite throttle is preheated to 200 to 400 degrees Celsius before deployment.

[0042] In some embodiments, the cross-sectional shape of the variable cross-section guide rib is trapezoidal or streamlined.

[0043] In some embodiments, the overall shape of the composite throttle plug is macroscopically a combination of an upper conical shape and a lower cylindrical shape.

[0044] In some embodiments, the inner core is provided with a hollow compensation cavity, and the height of the center of mass can be precisely adjusted by changing the volume of the hollow compensation cavity.

[0045] In some embodiments, the plate-shaped corundum powder in the alumina-magnesia refractory layer has a particle size distribution of 0.045 to 0.15 mm.

[0046] In some embodiments, the heat-resistant stainless steel fibers have a length of 10 to 20 mm and a diameter of 0.3 to 0.6 mm.

[0047] In some embodiments, in step S20, the inner wall of the dispensing tube of the dispensing device is coated with a solid lubricant, which is molybdenum disulfide or graphite.

[0048] In some embodiments, the roughness of the inner wall of the bottom hemispherical cavity of the composite throttle plug is greater than the roughness of its outer surface.

[0049] In some embodiments, the thickness of the asymmetric guide vane gradually decreases from the root to the edge, with a root thickness of 20 to 40 mm and an edge thickness of 5 to 15 mm.

[0050] In some embodiments, the composite swirl plug is suspended at a depth of 50 to 150 mm above the upper edge of the nozzle in molten steel.

[0051] In some embodiments, the raw material of the refractory functional layer further includes 1 to 4 parts of silicon carbide particles with a particle size of 1 to 3 mm, which are used to improve the slag erosion resistance of the plug body.

[0052] In some embodiments, the tilt angle of the automatic delivery rail is 45 to 75 degrees.

[0053] In some embodiments, the infrared liquid level detector has a sampling frequency of 10 to 50 times per second.

[0054] In some embodiments, the composite throttling plug is subjected to ultrasonic non-destructive testing after preparation to remove individuals with internal cracks or pores.

[0055] In some embodiments, the spraying pressure of the anti-oxidation coating is controlled at 0.4 to 0.6 MPa.

[0056] In some embodiments, a transition layer is provided between the inner core of the composite rotary stopper and the refractory functional layer. The thickness of the transition layer is 2 to 5 millimeters, and the material is refractory paste containing flexible graphite fibers.

[0057] In some embodiments, the top starting point of the variable cross-section guide rib is 20 to 50 mm away from the top of the rotator plug.

[0058] In some embodiments, in step S30, when the fluctuation of molten steel flow at the nozzle is detected to exceed 15% of a preset threshold, the flow field is stabilized by adjusting the argon blowing flow rate.

[0059] In some embodiments, the overall volume of the composite throttle is 0.005 to 0.015% of the steel enclosure volume.

[0060] In some embodiments, the calcium aluminate cement contains 70 to 80% alumina.

[0061] In some embodiments, the rate of change of the helix angle of the asymmetric guide vane is 0.5 to 1.2 degrees per centimeter of descent height.

[0062] In some embodiments, the diameter of the lower cylindrical portion of the composite swivel plug is slightly less than 0.9 times the inner diameter of the nozzle.

[0063] In some embodiments, the reduction sintering environment in step S10 is a hydrogen atmosphere or a decomposed ammonia atmosphere.

[0064] In some embodiments, the composite stopcock is vacuum-packed or covered with a moisture-proof film during storage.

[0065] In some embodiments, in step S20, the deviation of the placement position is controlled within 50 mm radially from the centerline of the sprue.

[0066] In some embodiments, the serrated staggered structure of the asymmetric guide vane has a water-facing angle of 30 to 45 degrees.

[0067] In some embodiments, the inner core of the composite rotary stopper is mechanically locked to the fire-resistant functional layer by multiple stainless steel pins.

[0068] In some embodiments, the specific surface area of ​​the activated alumina micropowder is 150 to 250 square meters per gram.

[0069] In some embodiments, the spinel powder is magnesium-rich spinel, wherein the magnesium oxide content is 22% to 28%.

[0070] In some embodiments, in step S30, the criterion for determining the end of pouring is that the slag sensor at the slag inlet continuously detects a slag signal for 0.5 to 1 second.

[0071] In some embodiments, the hook or ring surface of the composite rotary stopper is coated with a refractory slurry protective layer.

[0072] In some embodiments, the total surface area of ​​the asymmetric guide vanes accounts for 40 to 60% of the plug body side area.

[0073] In some embodiments, the scrap steel shavings in the inner core have an average size of 2 to 5 millimeters.

[0074] In some embodiments, the composite throttle valve is rapidly preheated by an induction heating device before deployment.

[0075] In some embodiments, the refractory functional layer is heated at a rate of 10 to 20 degrees Celsius per hour during the baking process.

[0076] In some embodiments, the center of mass of the composite throttle plug is located at 0.35 to 0.45 of the total height (measured from bottom to top).

[0077] In some embodiments, the windward side of the variable cross-section guide bar is provided with tiny turbulence pits with a diameter of 2 to 5 mm and a depth of 1 to 3 mm.

[0078] In some embodiments, the mold for preparing the composite rotor is made of high-strength polyurethane or silicone.

[0079] In some embodiments, in step S10, the density of the pressed core blank is 5.8 to 6.5 grams per cubic centimeter.

[0080] In some embodiments, the bottom of the hemispherical cavity of the composite rotary plug is provided with a pressure relief hole with a diameter of 3 to 8 mm.

[0081] In some embodiments, the tip radius of the asymmetric guide vane is 2 to 5 millimeters.

[0082] In some embodiments, in step S20, the end of the automatic delivery slide rail is provided with a buffer and shock absorption mechanism.

[0083] In some embodiments, the overall design life of the composite rotary plug is one ladle pouring cycle.

[0084] In some embodiments, the graphite powder in the antioxidant coating has a particle size of 200 to 400 mesh.

[0085] In some embodiments, the refractory functional layer of the composite rotary plug has the following particle size distribution: 30 to 40% of the particles are 3 to 5 mm, and 25 to 35% are 1 to 3 mm.

[0086] In some embodiments, in step S30, when the molten steel level drops to 100 mm above the nozzle, the swivel plug completely covers the central area of ​​the nozzle.

[0087] In some embodiments, the asymmetric guide vanes of the composite swirl plug have a certain degree of overlap in the vertical direction, with an overlap coefficient of 1.1 to 1.3.

[0088] In some embodiments, the porosity of the refractory functional layer is controlled to be between 12% and 18%.

[0089] In some embodiments, the inner core of the composite stopcock is impregnated with rust-preventive oil after sintering.

[0090] In some embodiments, in step S10, the amount of adhesive added is finely adjusted within the range of 5 to 8% based on the ambient humidity.

[0091] In some embodiments, the surface of the composite throttle plug is provided with a laser-etched production batch number and a quality traceability QR code.

[0092] In some embodiments, the helical trajectory of the asymmetric guide vane conforms to the Archimedes helix equation.

[0093] In some embodiments, in step S20, the control system of the feeding device communicates with the main control PLC of the continuous casting machine.

[0094] In some embodiments, the composite throttle plug is transported using a specially designed shockproof bracket.

[0095] In some embodiments, the magnesium oxide in the refractory functional layer is derived from sintered magnesia or fused magnesia.

[0096] In some embodiments, during step S30, the ladle tilt angle at the end of the pouring process is maintained at 2 to 5 degrees to accommodate the eccentric effect of the rotary stopper.

[0097] In some embodiments, the radial projection length of the asymmetric guide vanes of the composite swirl plug is 0.3 to 0.5 times the maximum radius of the plug body.

[0098] In some embodiments, the reduction sintering holding time of the inner core is 4 to 8 hours.

[0099] In some embodiments, the overall appearance of the composite throttle plug is light gray or beige.

[0100] In some embodiments, in step S10, the casting pressure of the refractory functional layer is 0.1 to 0.2 MPa.

[0101] In some embodiments, the hemispherical cavity depth of the composite throttle plug is 20 to 40 millimeters.

[0102] In some embodiments, the edge hardness of the asymmetric guide vane reaches a Mohs hardness of 7 to 8.

[0103] In some embodiments, in step S20, the detection accuracy deviation of the infrared liquid level detector is less than or equal to 5 millimeters.

[0104] In some embodiments, the volume fraction of stainless steel fibers in the refractory functional layer of the composite rotor plug is 0.5 to 1.5%.

[0105] In some embodiments, in step S30, the Reynolds number of the molten steel flow field around the throttle plug is controlled in the range of 100,000 to 500,000.

[0106] In some embodiments, the packaging box of the composite stopcock contains a desiccant and a deoxidizer.

[0107] In some embodiments, the surface of the asymmetric guide vane has a micro-nano-scale hydrophobic structure, achieved by coating with silicone resin.

[0108] In some embodiments, in step S10, the purity of the reduced iron powder in the inner core is greater than or equal to 98%.

[0109] In some embodiments, the centroid adjustment balance block of the composite rotator is made of tungsten alloy and is embedded at the bottom of the inner core.

[0110] In some embodiments, the compressive strength of the fire-resistant functional layer is greater than or equal to 60 MPa.

[0111] In some embodiments, in step S20, the actuator of the dispensing device is driven by a cylinder or a servo motor.

[0112] In some embodiments, the asymmetric guide vanes of the composite swirl plug generate a rotational torque of 5 to 15 Nm when subjected to the impact of high-temperature molten steel.

[0113] In some embodiments, in step S30, the rotational speed of the stopcock is controlled to be between 10 and 30 revolutions per minute.

[0114] In some embodiments, the refractory functional layer of the composite rotary plug has a linear change rate of -0.2 to +0.5% at high temperatures.

[0115] In some embodiments, in step S10, the mixer speed is set to 40 to 80 revolutions per minute.

[0116] In some embodiments, the shear strength of the interface between the inner core of the composite rotator and the refractory layer is greater than or equal to 5 MPa.

[0117] In some embodiments, the serrated structure of the asymmetric guide vanes is obtained by machining molds using precision CNC machine tools.

[0118] In some embodiments, in step S20, the drop height is 300 to 800 mm above the liquid surface.

[0119] In some embodiments, the overall thermal conductivity of the composite rotator is 1.5 to 2.5 watts per meter Kelvin.

[0120] In some embodiments, the spinel powder in the refractory functional layer has a particle size of 200 to 325 mesh.

[0121] In some implementations, in step S30, the local resistance loss caused by the rotary valve is compensated by adjusting the opening of the slide plate.

[0122] In some embodiments, the wear rate of the composite rotary plug during casting is less than 0.5 mm per minute.

[0123] In some embodiments, the helix angle of the asymmetric guide vane has an abrupt change point at the middle of the vane.

[0124] In some embodiments, in step S10, the temperature control accuracy of the baking oven is ±2 degrees Celsius.

[0125] In some embodiments, the inner core of the composite throttle plug is shot-blasted for strengthening.

[0126] In some embodiments, the initial setting time of the calcium aluminate cement in the refractory functional layer is 1 to 3 hours.

[0127] In some embodiments, the dispensing device is equipped with a dual-station backup in step S20.

[0128] In some embodiments, the ratio of the lift generated by the asymmetric guide vanes of the composite swirl plug in the flow field to the plug's own weight is 0.1 to 0.2.

[0129] In some embodiments, in step S30, the argon blowing intensity at the bottom of the ladle is switched to a micro-blowing mode, with a gas flow rate of 10 to 30 liters per minute.

[0130] In some embodiments, the hemispherical cavity of the composite throttle plug has the function of collecting minute inclusions.

[0131] In some embodiments, the distribution of silicon carbide particles in the refractory functional layer exhibits a gradient change, with the concentration in the outer layer being higher than that in the inner layer.

[0132] In some embodiments, in step S10, the material of the pressing mold is Cr12MoV mold steel.

[0133] In some embodiments, the asymmetric guide vanes of the composite swirl plug are coated with a special high-temperature resistant ceramic ink.

[0134] In some implementations, in step S20, a laser rangefinder is used for real-time position correction during the deployment process.

[0135] In some embodiments, the overall mass deviation of the composite throttle plug is controlled within ±1%.

[0136] In some embodiments, the raw material formulation of the refractory functional layer also contains 0.5 to 1.5 parts of metallic aluminum powder to improve the density of the material.

[0137] In some embodiments, in step S30, the vibration frequency of the rotary valve is controlled at 5 to 15 Hz to prevent slag particles from adhering.

[0138] In some embodiments, the inner core of the composite rotary plug is provided with a heat dissipation channel that runs through the center, which plays a certain cooling role in the initial stage of casting.

[0139] In some embodiments, the root of the asymmetric guide vane is provided with a rounded transition, with a rounded radius of 10 to 20 millimeters.

[0140] In some embodiments, in step S10, the dew point in the sintering atmosphere is controlled below -40 degrees Celsius.

[0141] In some embodiments, the fire-resistant functional layer of the composite throttling plug has a flexural strength of greater than or equal to 10 MPa at 1600 degrees Celsius.

[0142] In some embodiments, in step S20, the surface of the slide rail of the dispensing device is plated with hard chrome.

[0143] In some embodiments, the asymmetric guide vanes of the composite swirl plug have a non-uniform diameter fan shape projected onto the horizontal plane.

[0144] In some implementations, during step S30, the continuous casting machine speed remains stable, with fluctuations within ±0.05 meters per minute.

[0145] In some embodiments, an expansion buffer pad is provided at the interface between the inner core of the composite rotary plug and the refractory functional layer.

[0146] In some embodiments, the alumina micropowder in the refractory functional layer adopts a multi-peak distribution ratio.

[0147] In some embodiments, in step S10, the mold after casting is cured in a constant temperature and humidity chamber.

[0148] In some embodiments, the overall structure of the composite throttle plug is optimized through finite element fluid-structure interaction analysis.

[0149] In some embodiments, the number of asymmetric guide vanes is adjusted according to the ladle capacity; 3 vanes are used for 100-ton ladles, and 4 to 6 vanes are used for 200-ton ladles and above.

[0150] In some implementations, the action response time of the dispensing device in step S20 is less than 0.5 seconds.

[0151] In some embodiments, the surface roughness of the composite rotator is adjusted by a sandblasting process.

[0152] In some embodiments, the stainless steel fibers in the refractory functional layer are surface chemically modified to enhance their bonding strength with the cement matrix.

[0153] In some embodiments, in step S30, the horizontal drift of the swivel plug above the nozzle is controlled to be within 50 mm.

[0154] In some embodiments, the inner core of the composite throttle plug employs a segmented counterweight design.

[0155] In some embodiments, the ratio of the serration depth to the tooth pitch of the asymmetric guide vane is 0.5 to 0.8.

[0156] In some embodiments, in step S10, the average particle size of the reduced iron powder is 45 to 75 micrometers.

[0157] In some embodiments, the packaging bag of the composite stopcock is filled with high-purity nitrogen.

[0158] In some embodiments, the spinel powder in the refractory functional layer is prepared by in-situ synthesis.

[0159] In some embodiments, in step S30, the tilt angle of the ladle is adjusted so that the rotary valve is always at the lowest point of gravitational potential energy directly above the nozzle.

[0160] In some embodiments, the asymmetric guide vanes of the composite swirl plug undergo minute shape memory deformation upon heating, further optimizing the guide angle.

[0161] In some embodiments, in step S10, the moisture content of the mixture is detected online using a microwave moisture meter.

[0162] In some embodiments, the overall density of the composite throttling plug decreases slightly during the casting process due to surface melting loss, with the decrease controlled within 5%.

[0163] In some embodiments, the fused white corundum particles in the refractory functional layer undergo two processes: crushing and ball milling.

[0164] In some embodiments, in step S20, the guide tube of the dispensing device is provided with an anti-stick coating.

[0165] In some embodiments, the asymmetric guide vanes of the composite swirl plug are provided with flow-diverting orifices at their ends.

[0166] In some embodiments, in step S30, the molten steel level monitoring system and the suspension position of the rotary valve are controlled in a closed-loop linkage.

[0167] In some embodiments, the inner core surface of the composite rotator is plated with a nickel-phosphorus alloy with a thickness of 10 to 30 micrometers.

[0168] In some embodiments, the heat-resistant stainless steel fibers in the fire-resistant functional layer are made of 310S or 304.

[0169] In some embodiments, in step S10, the heating rate of the sintering furnace is 100 degrees Celsius per hour below 500 degrees Celsius and 50 degrees Celsius per hour above 500 degrees Celsius.

[0170] In some embodiments, the overall shape of the composite throttle plug conforms to a streamlined drag-reduction design.

[0171] In some embodiments, the edges of the asymmetric guide vanes are provided with minute protrusions to induce local turbulence.

[0172] In some embodiments, in step S20, the length of the slide rail of the dispensing device is 2 to 4 meters.

[0173] In some embodiments, the fire-resistant functional layer of the composite throttle plug has good thermal shock resistance, with a water-cooling cycle of 1100 degrees Celsius or more of 15 cycles.

[0174] In some embodiments, in step S30, the suspension stability of the spool plug is finely adjusted by adjusting the argon blowing pressure at the nozzle.

[0175] In some embodiments, the inner core of the composite rotary stopper is infused with 0.5% zinc stearate as a lubricant during the pressing process.

[0176] In some embodiments, the helix angle variation curve of the asymmetric guide vane exhibits an exponential distribution.

[0177] In some embodiments, the stirring time of the refractory material in step S10 is not less than 15 minutes.

[0178] In some embodiments, the surface coating of the composite throttle plug rapidly forms a dense glaze upon contact with molten steel.

[0179] In some embodiments, the tabular corundum powder in the refractory functional layer contains 0.5 to 1.0% by mass of titanium oxide to improve sintering performance.

[0180] In some implementations, the control logic of the dispensing device in step S20 includes an anti-misdispensing locking function.

[0181] In some embodiments, the residue of the composite rotator plug after casting is disposed of together with the steel slag.

[0182] In some embodiments, the radial dimension of the asymmetric guide vane gradually increases from top to bottom.

[0183] In some embodiments, in step S30, the eccentricity of the rotary valve is maintained at 0.1 to 0.2 times the nozzle radius.

[0184] In some embodiments, the inner core of the composite throttle plug is adjusted for final counterweight using a hollow lead-filling process.

[0185] In some embodiments, the calcium aluminate cement in the refractory functional layer has a particle size distribution of less than or equal to 5% residue on a 325-mesh sieve.

[0186] In some embodiments, in step S10, the relative humidity of the curing environment is maintained above 90%.

[0187] In some embodiments, the overall structural strength of the composite throttling plug is sufficient to withstand a free fall impact from a height of 5 meters without breaking. Detailed Implementation

[0188] The various embodiments or implementation schemes in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments.

[0189] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with an embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0190] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0191] This invention provides a method for reducing residual molten steel in a ladle by adding a rotary valve, and a composite rotary valve used in this method. This solution constructs a physical intervention system capable of stable operation under high-temperature molten steel scouring conditions by systematically defining the internal material distribution, external geometry, and dispensing process parameters of the rotary valve.

[0192] In a first aspect, the present invention provides a method for reducing excess molten steel in a ladle by adding a stopcock, comprising the following steps: Step S10: Prepare a composite swirl plug with multi-stage flow channels. Structurally, the composite swirl plug consists of an inner core, a refractory functional layer covering the outer periphery of the inner core, and asymmetric guide vanes disposed on the surface of the refractory functional layer.

[0193] In the preparation of the inner core, the selected raw materials include scrap steel, reduced iron powder, and a binder. The average size of the scrap steel is controlled to be 2 to 5 mm, and the average particle size of the reduced iron powder is 45 to 75 micrometers with a purity of ≥98%. The binder is a phenolic resin or polyvinyl alcohol aqueous solution. The specific mass ratio is 100 parts scrap steel, 15 to 25 parts reduced iron powder, and 5 to 8 parts binder. These raw materials are mixed evenly in a mixer at a speed of 40 to 80 rpm, and the moisture content of the mixture is detected online using a microwave moisture meter. Subsequently, under a pressure of 200 to 300 MPa, the mixture is pressed into a green compact using a pressing mold made of Cr12MoV die steel, with the green compact density controlled to be 5.8 to 6.5 g / cm³. The pressed inner core green compact is then placed in a reduction sintering furnace and sintered in a reducing atmosphere of hydrogen or decomposed ammonia. The heating rate of the sintering furnace is set at 100 degrees Celsius per hour below 500 degrees Celsius and at 50 degrees Celsius per hour above 500 degrees Celsius. The core is held at 1000 to 1100 degrees Celsius for 4 to 8 hours, with the dew point in the sintering atmosphere maintained below -40 degrees Celsius. The sintered core has a density of 6.5 to 7.8 grams per cubic centimeter. To increase the bonding strength between the core and the subsequent refractory functional layer, the sintered core undergoes surface sandblasting or shot blasting to create a micro-roughened surface structure. In some embodiments, the core surface is also electroplated with a nickel-phosphorus alloy layer with a thickness of 10 to 30 micrometers, or mechanically locked to the refractory functional layer by multiple stainless steel pins.

[0194] The raw materials for the refractory functional layer, by weight, include: 45 to 60 parts of fused white corundum particles, 20 to 35 parts of tabular corundum fine powder, 5 to 12 parts of activated alumina micro powder, 3 to 8 parts of spinel powder, 4 to 9 parts of pure calcium aluminate cement, and 1 to 3 parts of heat-resistant stainless steel fiber. The fused white corundum particles are graded, with 30 to 40% being 3 to 5 mm, 25 to 35% being 1 to 3 mm, and the remainder being 0 to 1 mm. The tabular corundum fine powder has a particle size distribution of 0.045 to 0.15 mm. The activated alumina micro powder has a specific surface area of ​​150 to 250 square meters per gram. The spinel powder is magnesium-rich spinel, with a magnesium oxide content of 22 to 28% and a particle size of 200 to 325 mesh. The pure calcium aluminate cement contains 70 to 80% alumina, and its initial setting time is controlled within 1 to 3 hours. The heat-resistant stainless steel fibers are made of 310S or 304, with a length of 10 to 20 mm and a diameter of 0.3 to 0.6 mm, and the fiber surface is chemically modified. When preparing the refractory functional layer, the above raw materials are dry-mixed evenly, and then 4 to 6% water (by weight of the total raw materials) is added for wet mixing, with a stirring time of no less than 15 minutes.

[0195] The mixed refractory material is poured into a mold containing the inner core, with the pouring pressure controlled at 0.1 to 0.2 MPa. The mold is made of high-strength polyurethane or silicone. After pouring, it is naturally cured in a constant temperature and humidity chamber with a relative humidity of over 90% for 24 to 48 hours. Then, it enters the baking process, baking at 110 to 200 degrees Celsius for 12 to 24 hours, with a heating rate controlled at 10 to 20 degrees Celsius per hour. The temperature control accuracy of the baking oven is ±2 degrees Celsius. By adjusting the volume ratio of the inner core to the refractory functional layer, the overall density of the composite rotary stopper is adjusted to 4.5 to 5.5 grams per cubic centimeter.

[0196] The composite vortex deflector is externally equipped with asymmetric guide vanes, which are spirally distributed on the outer surface of the refractory functional layer. The helix angle of the vanes gradually decreases from 30 degrees to 15 degrees from the top to the bottom, with a rate of change of 0.5 to 1.2 degrees per centimeter of descent height. The spiral trajectory conforms to the Archimedes' equation. There are 3 to 6 vanes, and the arc length central angle between adjacent vanes is non-equally distributed, with a difference of 5 to 15 degrees between adjacent central angles. The radial outer edge of the asymmetric guide vanes has a serrated staggered structure, with a serration depth of 10 to 20 mm, a tooth pitch of 15 to 30 mm, and an angle of 30 to 45 degrees on the water-facing surface of the serrations. The thickness of the vanes gradually decreases from the root to the edge, with a root thickness of 20 to 40 mm and an edge thickness of 5 to 15 mm. The root has a rounded transition with a radius of 10 to 20 mm.

[0197] The surface of the composite rotor plug is also coated with an anti-oxidation coating with a thickness of 0.5 to 1.5 mm, the composition of which includes silicon carbide powder, graphite powder (particle size 200 to 400 mesh), and aluminum dihydrogen phosphate binder (mass fraction 15 to 25%). The spraying pressure is controlled at 0.4 to 0.6 MPa.

[0198] Step S20: When the ladle is filled to a height of 3 to 5 times the inner diameter of the nozzle, the composite swivel plug is vertically placed directly above the ladle nozzle using the launching device.

[0199] The dispensing device includes an infrared liquid level detector, an automatic dispensing slide rail, and a control system. The infrared liquid level detector monitors the liquid level in the ladle in real time, sampling at a frequency of 10 to 50 times per second, with a detection accuracy deviation of less than or equal to 5 millimeters. When the liquid level reaches the preset range of 300 to 500 millimeters, the automatic dispensing slide rail is triggered. The automatic dispensing slide rail has an inclination angle of 45 to 75 degrees, a length of 2 to 4 meters, and a surface treated with hard chrome plating and coated with molybdenum disulfide solid lubricant. The dispensing speed is controlled at 2 to 5 meters per second, and the dispensing height is 300 to 800 millimeters above the liquid level. The dispensing position deviation is controlled within 50 millimeters radially from the centerline of the nozzle. Before dispensing, the composite rotary valve is preheated to 200 to 400 degrees Celsius using an induction heating device.

[0200] Step S30: The composite rotary plug sinks under gravity in the molten steel and floats above the nozzle.

[0201] The composite vortex stopper has a concave hemispherical cavity at its bottom, with a diameter 0.4 to 0.6 times the maximum diameter of the composite vortex stopper and a depth of 20 to 40 mm. The inner wall of the cavity has 8 to 12 radially distributed raised ribs, and the roughness of the inner wall is greater than that of the outer surface of the stopper. The suspension depth of the vortex stopper in the molten steel is controlled at 50 to 150 mm above the upper edge of the nozzle. Asymmetric guide vanes generate tangential resistance to the molten steel flowing towards the nozzle, dividing the single macroscopic vortex into multiple micro-turbulent clusters. The Reynolds number of the molten steel flow field around the vortex stopper is controlled within the range of 100,000 to 500,000. By adjusting the opening of the nozzle slide, the molten steel flow rate is maintained at 3 to 5 tons per minute. At the end of the pouring process, the ladle tilt angle is maintained at 2 to 5 degrees. When the fluctuation of molten steel flow at the nozzle exceeds a preset threshold of 15%, the flow field is stabilized by adjusting the argon blowing flow at the bottom of the ladle. At this time, the argon blowing intensity is switched to micro-blowing mode, with a gas flow rate of 10 to 30 liters per minute. The criterion for determining the end of casting is that the slag entrapment sensor at the nozzle continuously detects a slag signal for 0.5 to 1 second.

[0202] Secondly, the present invention provides a composite swivel plug for use in the above-described method. The ratio of the overall height to the maximum diameter of the composite swivel plug is 1.2 to 1.8, and its macroscopic shape is a combination of an upper conical shape and a lower cylindrical shape.

[0203] The composite rotary stopper includes a centrally symmetrical high-density inner core made of sintered iron-based alloy. The inner core contains a hollow compensation cavity; by changing the volume of this cavity, the height of the center of mass is adjusted to position the center of mass at 0.35 to 0.45 of the total height (measured from bottom to top). A tungsten alloy center of mass adjustment balancing block can also be embedded at the bottom of the inner core.

[0204] The inner core is externally covered by an alumina-magnesia refractory layer (i.e., a refractory functional layer). This refractory layer also contains 2 to 5% by mass of zirconium oxide micropowder (average particle size 1 to 5 micrometers) and 1 to 4 parts by mass of silicon carbide particles (particle size 1 to 3 millimeters). The particle size distribution of the tabular corundum fine powder in the alumina-magnesia refractory layer is 0.045 to 0.15 millimeters. The porosity of the refractory layer is controlled at 12 to 18%, the compressive strength is greater than or equal to 60 MPa, and the flexural strength at 1600 degrees Celsius is greater than or equal to 10 MPa.

[0205] The surface of the alumina-magnesia refractory layer is provided with variable cross-section guide ribs (i.e., guide vanes), whose cross-sectional area gradually increases from top to bottom, and whose cross-sectional shape is trapezoidal or streamlined. The surface roughness Ra of the guide ribs is 12.5 to 25 micrometers. The edges of the guide ribs are embedded with wear-resistant ceramic strips made of silicon nitride or boron carbide. The total surface area of ​​the asymmetric guide vanes accounts for 40 to 60% of the side area of ​​the plug body, and their radial projection length is 0.3 to 0.5 times the maximum radius of the plug body.

[0206] The composite rotary stopper has a hook or ring at its top, made of alloy steel with a melting point of 1400 to 1500 degrees Celsius, and coated with a protective layer of refractory mortar. A transition layer with a thickness of 2 to 5 mm is provided between the inner core and the refractory functional layer, and the material is refractory mortar containing flexible graphite fibers.

[0207] The technical solution of the present invention will be further described below through specific embodiments.

[0208] Example 1 Preparation of composite throttle plugs: Inner core: 100kg of scrap steel, 20kg of reduced iron powder, and 6kg of phenolic resin are mixed. The mixture is pressed into a spindle-shaped green body under 250MPa and sintered at 1050 degrees Celsius for 6 hours, with a density of 7.2g / cm³.

[0209] Refractory functional layer: 50 parts fused white fused alumina, 30 parts tabular fused alumina, 8 parts activated alumina, 5 parts spinel powder, 6 parts calcium aluminate cement, and 2 parts stainless steel fiber. Add 5% water and mix.

[0210] Structural design: The helix angle is reduced from 30 degrees to 15 degrees, the number of blades is 3, and the center angle difference is 10 degrees. The overall density is 5.0 g / cm³.

[0211] Dispensing parameters: Dispense when the liquid level is 400mm, and dispense at a speed of 3m / s.

[0212] Example 2 Based on Example 1, the number of blades was changed to 4, the rate of change of helix angle was 1.0 degrees per centimeter, and the core density was adjusted to 7.5 g / cm³.

[0213] Example 3 Based on Example 1, 3% zirconium oxide micro powder was added to the refractory functional layer, and the inner core was mechanically locked with multiple stainless steel pins, with the overall density adjusted to 5.2 g / cm³.

[0214] Example 4 Based on Example 1, the serration depth of the asymmetric guide vane is set to 15mm, the tooth pitch is set to 25mm, and a pressure relief hole with a diameter of 5mm is provided at the bottom of the hemispherical cavity.

[0215] Comparative Example 1 The same refractory material as in Example 1 is used, but without a high-density inner core. The entire throttle plug is made of a single refractory material with a density of 2.8 g / cm³.

[0216] Comparative Example 2 The same material as in Example 1 is used, but the guide vanes are symmetrically distributed (the central angle is equally divided), and the vane surface has no serrated structure.

[0217] Comparative Example 3 It adopts the same structure as Example 1, but the helix angle is a fixed value of 25 degrees and does not change with the height.

[0218] Industrial tests were conducted on the above embodiments and comparative examples during the casting process of a 200-ton steel ladle. The monitoring data are shown in the table below:

[0219] Based on experimental data analysis, Examples 1 to 4 significantly reduced the critical swirl level by employing a combination of a high-density inner core and asymmetric variable cross-section guide vanes. In contrast, Comparative Example 1, lacking a high-density inner core, resulted in the swirl stopper being unable to stabilize above the nozzle due to buoyancy in the molten steel, leading to a higher swirl level and a significant increase in the amount of molten steel remaining in the casting. Comparative Example 2, using symmetrical vanes, could not effectively disrupt the axisymmetric balance of the flow field, and its vortex suppression effect was weaker than that of the examples. Comparative Example 3, with its fixed helix angle, could not adapt to the change in flow velocity as the liquid level decreased, resulting in limited guiding effect. Example 4, through the combination of a serrated structure and pressure relief orifices, achieved the lowest swirl level and the lowest amount of molten steel remaining in the casting, demonstrating the disruptive effect of asymmetric physical intervention on the dynamic conditions of the flow field.

[0220] In practical implementation, the shear strength of the interface between the inner core and the refractory layer of the composite rotary stopper must be greater than or equal to 5 MPa. The overall structural strength of the composite rotary stopper must be able to withstand a free fall impact from a height of 5 meters without breaking. During storage, the composite rotary stopper is vacuum-packed or covered with a moisture-proof film, and the packaging bag is filled with high-purity nitrogen and contains desiccant and deoxidizer.

[0221] In step S10 above, the casting pressure of the refractory functional layer is 0.1 to 0.2 MPa. Precise control of the heating rate during baking ensures the slow removal of moisture from the material, preventing microcracks caused by excessive steam pressure. In step S20, the actuator of the dispensing device is driven by a cylinder or servo motor, with a response time of less than 0.5 seconds. In step S30, the rotational speed of the rotary valve is maintained at 10 to 30 revolutions per minute under the drive of the flow field, generating a rotational torque of 5 to 15 Nm.

[0222] This invention achieves precise induction of the flow field at the end of the ladle's lifecycle through a systematic design of the vortex-blocking plug, encompassing everything from microscopic material composition (such as the micro-expansion effect of spinel powder and the reinforcement of stainless steel fibers) to macroscopic structural morphology (such as asymmetric blades with an Archimedean spiral distribution and serrated edges). The high-density inner core ensures the plug's spatial stability under the intense scouring and argon-blown disturbances of molten steel at temperatures between 1550 and 1650 degrees Celsius. Meanwhile, the asymmetric guide blades, by altering the radial velocity component of fluid particles and reducing their tangential velocity component, disrupt the angular momentum balance required for vortex development, thereby delaying slag entrainment and minimizing residual molten steel.

[0223] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for reducing residual molten steel in a ladle by adding a stopcock, characterized in that, Includes the following steps: S10: Prepare a composite swirl stopper; the composite swirl stopper includes an inner core, a refractory functional layer covering the outer periphery of the inner core, and asymmetric guide vanes disposed on the surface of the refractory functional layer; the density of the inner core is 6.5 to 7.8 g per cubic centimeter; S20: When the ladle is poured to a height of 3 to 5 times the inner diameter of the nozzle, the composite rotary stopper is vertically placed directly above the ladle nozzle. S30: The composite vortex plug is suspended above the nozzle and uses the asymmetric guide vanes to generate tangential resistance to the molten steel flowing towards the nozzle, dividing the single macroscopic vortex into tiny turbulent clusters until the casting is completed.

2. The method according to claim 1, characterized in that, In step S10, the method for preparing the inner core includes: mixing waste steel scrap, reduced iron powder and binder in a mass ratio of 100:15 to 25:5 to 8, pressing them into shape under a pressure of 200 to 300 MPa, and performing reduction sintering at 1000 to 1100 degrees Celsius.

3. The method according to claim 1, characterized in that, In step S10, the raw materials of the refractory functional layer include, by weight: 45 to 60 parts of fused white corundum particles, 20 to 35 parts of tabular corundum fine powder, 5 to 12 parts of activated alumina micro powder, 3 to 8 parts of spinel powder, 4 to 9 parts of pure calcium aluminate cement, and 1 to 3 parts of heat-resistant stainless steel fiber.

4. The method according to claim 1, characterized in that, The asymmetric guide vanes are spirally distributed on the outer surface of the fire-resistant functional layer, and the helix angle of the vanes gradually decreases from 30 degrees to 15 degrees from the top to the bottom. The number of asymmetric guide vanes is 3 to 6, and the difference in arc length center angle between adjacent vanes is 5 to 15 degrees.

5. The method according to claim 4, characterized in that, The asymmetric guide vane has a serrated interlaced structure on its radial outer edge, with the serrations having a depth of 10 to 20 mm and a pitch of 15 to 30 mm.

6. The method according to claim 1, characterized in that, The overall density of the composite spool blocker is 4.5 to 5.5 grams per cubic centimeter; the bottom of the composite spool blocker is provided with a concave hemispherical cavity, the diameter of which is 0.4 to 0.6 times the maximum diameter of the composite spool blocker.

7. The method according to claim 1, characterized in that, In step S20, the liquid level in the ladle is monitored in real time by an infrared liquid level detector. When the liquid level reaches 300 to 500 mm, the automatic delivery slide rail is triggered to send the composite rotary plug in at a delivery speed of 2 to 5 meters per second.

8. A composite rotary stopper for use in the method of any one of claims 1 to 7, characterized in that, The composite rotator includes: The centrally symmetrical high-density inner core is made of sintered iron-based alloy. An aluminum-magnesium refractory layer covering the outside of the inner core; The variable cross-section guide ribs are disposed on the surface of the aluminum-magnesium refractory layer, and the cross-sectional area of ​​the variable cross-section guide ribs gradually increases from top to bottom.

9. The composite paddle plug according to claim 8, characterized in that, The high-density inner core is spindle-shaped, with its maximum radial dimension located at the lower third of the height direction; the ratio of the total height to the maximum diameter of the composite swivel plug is 1.2 to 1.

8.

10. The composite paddle plug according to claim 8, characterized in that, The aluminum-magnesium refractory layer contains 2 to 5% by mass of zirconium oxide micropowder, the average particle size of which is 1 to 5 micrometers; the surface of the composite throttle blocker is coated with an anti-oxidation coating, the thickness of which is 0.5 to 1.5 millimeters.

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