A method for improving the tapping rate of a ladle by using high manganese steel special drainage sand

Abstract

This invention provides a method for improving the automatic pouring rate of steel ladles using high-manganese steel-specific diverting sand. The method involves: cleaning the surface of the nozzle seat bricks with a coarse oxygen tube, cleaning the inside of the nozzle eye with a fine oxygen tube until the oxygen tube stops igniting, installing the slide plate, cleaning the fire mud a second time, closing the mechanism, waiting for the first time, and then purging again; using a gradient filling method, the lower layer uses magnesium olivine sand, and the upper layer uses high-manganese steel-specific diverting sand. The composition and mass percentage of the high-manganese steel-specific diverting sand are: MnO content 6-8%, MgO content 2-3%, magnesium iron spinel 35-40%, zircon content 20-24%, and carbon content 3-5%; the upper layer of high-manganese steel-specific diverting sand forms mushroom-shaped bulges covering the nozzle seat bricks. The slide plate opens fully at once, achieving automatic pouring with an automatic pouring rate of over 99.4%.

Description

Technical Field

[0001] This invention relates to the field of iron and steel metallurgy technology, and in particular to a method for improving the self-starting rate of steel ladles by using special diversion sand for high manganese steel. Background Technology

[0002] In continuous casting production systems, the automatic ladle opening rate is a core factor affecting the continuous casting machine's operating rate, billet quality, and production costs. For high-manganese steel (Mn≥10.0%), the high volatility and strong reducing properties of manganese cause abnormal sintering of traditional guide sand in the nozzle area, resulting in an automatic ladle opening rate that has long been below 75% (compared to ≥98% for conventional steel grades). This defect forces production lines to rely on manual intervention methods such as oxygen burning, leading to secondary oxidation of molten steel, abnormal refractory material loss, and disrupted production rhythm.

[0003] I. The core contradiction of high-manganese steel initial casting failure

[0004] Chemical corrosion caused by manganese vapor penetration occurs when molten steel is left to stand at 1600–1650°C, resulting in a manganese vapor partial pressure as high as 10. -2 The manganese vapor diffuses deep into the pores of the guide sand, reacting with SiO2 to form low-melting-point manganese olivine (Mn2SiO4, melting point 1345℃), forming a glassy molten film that encapsulates the sand particles, completely destroying their loose structure.

[0005] The reducing densification effect, the oxides such as Fe2O3 and Cr2O3 in the highly active manganese-reduced sand (typical reaction: 3Mn + Cr2O3 → 2Cr + 3MnO), and the in-situ generated metallic chromium, iron and their alloys form a liquid-phase metal network at high temperature, making the sand layer exhibit a ceramic-like sintering state, and increasing the shear strength to more than 3 times that of ordinary steel.

[0006] Thermo-mechanical coupling mismatch resulted in a significantly higher solidification shrinkage rate (2.3–2.8%) for high-manganese steel compared to carbon steel (1.5–2.0%), while the coefficient of thermal expansion of conventional chromite sand (7.5 × 10⁻⁶) was lower. -6 The difference between the shrinkage behavior of the steel shell and the ℃ ( / ℃) leads to stress concentration at the interface, forming a "mechanical anchoring" type of blockage.

[0007] II. Technical Defects of Existing Diversion Sand Systems

[0008] Quartz sand-based materials (SiO2 > 80%) possess excellent fluidity (angle of repose ≤ 28°), but exhibit extremely poor resistance to manganese erosion. The violent reaction of manganese vapor with SiO2 leads to deep penetration, resulting in a casting failure rate > 60%. Chromite-based materials (Cr2O3 > 70%) show significantly improved erosion resistance, but the sharp edges of the natural sand particles result in a bulk density > 2.9 g / cm³ (exceeding the critical fluidization density of 2.6 g / cm³), deteriorating fluidity (angle of repose ≥ 42°), and leading to a casting fluidization failure rate > 40%. Pre-sintered magnesia-olivine sand improves fluidity through spherical particle design, but its resistance to manganese vapor penetration is insufficient, failing to prevent sintering caking caused by deep manganese diffusion.

[0009] III. Key Bottlenecks in Operating Processes

[0010] Incomplete cleaning of the sprue and traditional single-diameter oxygen pipe cleaning methods cannot simultaneously remove the slag on the surface of the bearing brick and the sintered layer deep within the cavity. Residual Mn2SiO4 slag (microhardness HV580) becomes the active nucleus for secondary sintering. The filling of the drainage sand is coarse and inefficient.

[0011] Fluctuations in sand addition (40–90 kg / bag) and the flat-laying stacking structure lead to a dual problem: excessive sand filling creates a compacted zone that induces molten steel penetration, while insufficient sand results in insulation failure; the flat-laying shape exacerbates the heat radiation from the molten steel and accelerates the compaction of the upper sand layer. Improper argon control...

[0012] Insufficient argon blowing intensity at the end of refining (<5 NL / min) causes deoxidation product Al2O3 to deposit in the nozzle area, reacting with infiltrated manganese to form high-melting-point Al2O3-MnO composite blockage material (melting point >1800℃). The lack of periodic strong stirring during the waiting period further exacerbates the enrichment of inclusions.

[0013] IV. Inherent Limitations of Industry Improvement Plans

[0014] The current technical approach presents three irreconcilable contradictions: the mutual exclusion of erosion resistance and fluidity, increasing the Cr2O3 content to enhance manganese erosion resistance, but the angularity of the sand particles leads to excessive bulk density and loss of self-fluidization ability; the opposition between high temperature resistance and low temperature crushing, adding fluxes such as borax to lower the initial melting temperature and promote casting, but causes boric acid erosion of the refractory at the sprue (increasing the erosion rate by 150%).

[0015] The conflict between long-term adaptability and structural stability is evident. Hollow spherical sand structures improve fluidity, but when the wall thickness is <50μm, manganese vapor breaks down the barrier to form a MnCr2O4 spinel hard shell, resulting in the loss of the initial casting function. The necessity of this technology is clear: the problem of initial casting in high-manganese steel continuous casting is essentially a superimposed effect of material chemical failure, thermomechanical mismatch, and operational discretization. At the material level, a single-component sand cannot simultaneously block manganese penetration channels and maintain low shear strength. At the operational level, there is a lack of quantitative standards for processes such as nozzle cleaning, sand addition control, and argon agitation. At the system level, a dynamic synergistic mechanism involving "refractory state - sand layer structure - molten steel cleanliness" has not been established. Summary of the Invention

[0016] This invention provides a method for improving the self-starting rate of steel ladles by using special high-manganese steel diversion sand, thus solving the following problems.

[0017] To achieve the above objectives, the present invention adopts the following technical solution: a method for improving the self-starting rate of steel ladle casting using special high-manganese steel guiding sand, the method comprising the following steps in sequence:

[0018] 1) Three-stage cleaning for hot repair of steel ladle: Use a coarse oxygen pipe to clean the steel slag on the surface of the nozzle seat brick, use a fine oxygen pipe to clean the inside of the nozzle until the oxygen pipe stops igniting, install the slide plate and clean the fire mud a second time, shut down the mechanism and wait for the first time before purging again.

[0019] 2) Adding diversion sand: A gradient filling method is adopted, with magnesium olivine sand in the lower layer and high manganese steel special diversion sand in the upper layer. The composition and mass percentage of the high manganese steel special diversion sand are: MnO content 6-8%, MgO content 2-3%, magnesium iron spinel 35-40%, zircon content 20-24%, carbon content 3-5%; the upper layer of high manganese steel special diversion sand forms a mushroom-shaped bulge covering the water nozzle seat brick.

[0020] Lower layer: Magnesia olivine sand is used to ensure basic fluidity and thermal insulation; Upper layer: MnO-MgO-magnesia iron spinel-zircon-carbon composite system is applied to achieve: MnO selectively oxidizes manganese vapor to generate high-melting-point FeMn2O4 (melting point 1705℃) to block penetration; MgO / spinel improves high-temperature stability, zircon buffers thermal stress; carbon component inhibits the densification of metal network.

[0021] Material Design Innovation: Constructing a "functionally graded" composite system. Lower Layer: Magnesia olivine sand (Mg2SiO4) ensures basic fluidity and thermal insulation, addressing defects directly: It directly targets the poor fluidity of chromite sand (angle of repose ≥ 42°) and the problem of upper layer caking caused by the thermal insulation failure of quartz sand. Refined Design: Particle Morphology Control: Pre-sintered spherical magnesium olivine sand is used to ensure its sphericity (ψ > 0.8), and the angle of repose is stably controlled at ≤ 30°, providing excellent basic fluidity and self-flowability for the entire sand column. Chemically Inert Layer: Magnesia olivine sand is mainly composed of MgO and SiO2, and its thermodynamic stability is superior to pure SiO. At the static temperature of high-manganese steel, its reactivity with manganese vapor is much lower than that of quartz sand. It mainly serves as a physical insulation layer, isolating the heat of the upper reaction zone from the lower nozzle channel, preventing premature preheating of the bottom of the sand layer by molten steel, which could lead to localized sintering. Cost and function balance: By placing it at the lower level, its excellent physical properties and relatively low cost are utilized to achieve the goal of controlling the overall cost without sacrificing key performance.

[0022] Upper Layer: MnO-MgO-magnesium iron spinel-zircon-carbon composite system – Active defense and structural stability are the core of the technology, with each component specifically addressing one or more existing defects. Corresponding defects: manganese vapor chemical erosion, reducing densification, thermo-mechanical mismatch anchoring. Detailed design and mechanism of action: MnO (manganese oxide) – a chemical barrier that “treats manganese with manganese.” Mechanism of action: Not simply added, but through formulation design, it is pre-synthesized at high temperatures with components such as Fe2O3 in the composite sand to form high-melting-point (1705℃) iron-manganese spinel (FeMn2O4). This phase is uniformly distributed on the surface of the sand grains. Defect resolution: When manganese vapor (Mn_(g)) seeps upwards, it dissolves in FeMn2O4 or reacts directly with FeO (Mn_{(g)} + FeO -> (Fe,Mn)O), transforming the destructive gaseous manganese reaction into a solid-phase spinel formation reaction. This process significantly slows down and blocks the penetration channels of manganese vapor into the deeper layers of the sand, fundamentally solving the problem of "deep melting" in quartz sand. MgO / Magnesium-Iron Spinel ((Mg,Fe)Al2O4) - High-Temperature Stability and Structural Toughness Framework Mechanism: High-purity MgO and synthetic magnesium-iron spinel constitute the high-temperature resistant main framework. MgO has extremely high thermal stability (melting point 2852℃) and does not react with manganese. The unique cubic crystal structure of magnesium-iron spinel results in an isotropic coefficient of thermal expansion (~8.2×10⁻⁶). -6 / ℃), and its temperature range is between that of steel shells and sand. Addressing shortcomings: Its superior resistance to manganese vapor erosion and penetration compensates for the deficiencies of pre-sintered magnesia olivine sand, outperforming chromite sand. Thermomechanical matching: Its moderate coefficient of thermal expansion effectively buffers the thermal expansion of high-manganese steel (23×10). -6The difference in shrinkage stress between the spinel particles (at / ℃) and the refractory material avoids "mechanical anchoring" blockage caused by stress concentration. It inhibits densification: the spinel particles are strong and not easily crushed, maintaining the porosity of the sand layer. Zircon (ZrSiO4) - Mechanism of action as a thermal stress buffer and micropore sealant: Zircon decomposes into ZrO2 and SiO2 at high temperatures (above 1540℃). This is an endothermic process and produces approximately 3-5% volume expansion. It addresses defects: Absorbs shrinkage stress: its decomposition expansion effect can actively offset some of the solidification shrinkage of high-manganese steel, further alleviating interfacial stress, and is a key auxiliary means to solve "thermal-mechanical mismatch". It seals pores: the active SiO2 produced by decomposition can quickly react with the surrounding MgO to form forsterite (Mg2SiO4), sealing the micropores between sand particles in situ, blocking the diffusion path of manganese vapor and the penetration channel of molten metal. Carbon (C)-reducing atmosphere protection and network blocking agent mechanism: A localized reducing atmosphere is formed at high temperatures, and the carbon film coats the surface of sand particles. Defect resolution: Inhibition of reduction reaction: By reducing the oxygen partial pressure, the reduction reaction of manganese vapor on oxides such as Fe2O3 and Cr2O3 in the sand is effectively suppressed, fundamentally eliminating the densification effect of "in-situ formation of metallic chromium, iron, and their alloys forming a liquid-phase metal network," thus maintaining the shear strength of the sand layer at a low level. Sintering barrier: The isolating effect of the carbon film prevents direct contact between sand particles, avoiding solid-phase sintering and maintaining the loose structure of the sand layer.

[0023] Three-stage cleaning process for ladle hot repair: Stage 1: Oxygen lance cleaning: Using a Φ25mm large-diameter oxygen lance to efficiently remove low-melting-point MnSiO4 slag from the surface of the sprue bricks. Stage 2: Mechanical milling: Using a carbide drill bit to physically break up the high-hardness sintered layer such as chromium-manganese spinel (MnCr2O4) deep within the nozzle cavity. Stage 3: Pulsed argon backflushing: Using 0.8MPa pulsed argon gas to thoroughly blow away all residual particles generated during cleaning from the nozzle channel. Results achieved: Elimination of secondary sintering nuclei: The removal rate of residual MnSiO4 slag (HV580) and spinel hard shell (HV>1100) in the nozzle area is increased from 70-80% using traditional methods to over 99.9%, fundamentally preventing them from acting as "active seeds" and inducing rapid secondary sintering in the next heat of molten steel. Ensuring unobstructed initial flow: This ensures absolute flatness and cleanliness of the contact surface between the sprue seat brick and the lower sliding plate, providing an ideal and consistent filling base for the diversion sand and eliminating "hidden blockages" caused by incomplete cleaning. Improving pouring consistency: The pouring failure rate caused by fluctuations in sprue cleaning conditions is reduced from over 15% to below 0.5%, ensuring highly consistent initial conditions for each pour and laying a solid foundation for a high pouring rate.

[0024] Mushroom-shaped Sand Filling Geometric Control: Optimizing sand layer density and thermal field distribution. Improvements include: 1. Center Thickening: Ensuring a stable sand layer thickness of 120-130mm directly above the sprue channel, providing sufficient thermal insulation. 2. Edge Slope: Controlling the top profile of the sand layer to a 45-60° "mushroom-shaped" protrusion, rather than a flat structure. 3. Precise Quantification: Controlling the sand addition accuracy to ±2kg / bag (target value 60kg). Results: 1. Suppressing Upper Claying: The "mushroom-shaped" protrusion reduces the direct thermal radiation projection area of ​​the molten steel surface on the top of the sand layer by more than 40%, significantly delaying the overheating and early sintering rate of the upper composite sand, allowing more time for successful casting. 2. Preventing Molten Steel Penetration: The center thickening layer ensures sufficient insulation thickness, preventing "burn-through" and molten steel penetration caused by an excessively thin sand layer. Precise sand addition avoids the formation of a compacted lower zone due to excessive sand filling, ensuring the uniformity of the overall porosity of the sand layer and enabling the static pressure of molten steel to effectively act on the entire sand column. 3. Ensuring fluidization initiation: Optimized density distribution and uniform pore structure reduce the overall critical fluidization gas consumption of the sand layer, ensuring that the sand column can smoothly achieve the "fluidization-collapse" transition at the moment of pouring, avoiding fluidization failure caused by the "arching" effect due to localized compaction.

[0025] Preferably, the coarse oxygen tube refers to an oxygen tube with a diameter Φ≥20mm, and the fine oxygen tube refers to an oxygen tube with a diameter Φ≤8mm.

[0026] Preferably, the particle size distribution of the high manganese steel special diversion sand meets the following requirements: ≥95% of particles with a diameter of 0.2-1.0mm, ≤3% of fine powder with a diameter of <0.2mm, and ≤0.3% of moisture content, and the mass ratio of FeO to CrO is controlled at 0.8-1.0.

[0027] Preferably, the upper layer of the diversion sand has a filling thickness of 200-240mm, and the lower layer has a filling thickness of about 460-500mm. The "fast filling and slow lifting" method is adopted: the filling cylinder is inserted into the bottom of the water inlet for rapid filling, and the cylinder is slowly lifted to avoid stratification.

[0028] Furthermore, the method for preparing the special diversion sand for high manganese steel includes the following steps in sequence:

[0029] a. Raw material preparation and pretreatment: Take electrolytic MnO powder, high-purity MgO powder, pre-synthesized magnesium iron spinel particles, zircon particles and flake graphite that meet the requirements respectively. Crush the pre-synthesized magnesium iron spinel particles and zircon particles, then classify them by particle size, and grind the flake graphite.

[0030] b. Ingredients and mixing: Weigh and mix the ingredients precisely according to the weight percentages described in step 2. Put all the raw materials into a high-efficiency mixing mill and dry mix them first to ensure that the various powders and particles are evenly distributed. Then add a composite binder accounting for 4-6% of the total weight of the raw materials and wet mix them until all materials are evenly coated with the binder and there is no white material.

[0031] c. Granulation and curing: The mixed wet material is fed into the granulator. By controlling the parameters of the granulator, it is formed into approximately spherical particles. The granulated wet particles are placed in the curing chamber for heat treatment to fully cure the binder and give the particles sufficient cold strength. This facilitates transportation and filling while ensuring that the particles maintain their structural integrity in the early stage of ladle baking.

[0032] d. Cooling and Packaging: After solidification, the granules are cooled and screened to remove fine powder and excessively large particles, resulting in finished high-manganese steel special guide sand. The sand is then sealed in packaging to prevent moisture absorption.

[0033] Preferably, the composite binder can be a phenolic resin or a sugar alcohol liquid.

[0034] Preferably, the heat treatment in step c is performed at a temperature of 180-220°C for 2-4 hours.

[0035] Preferably, in step a, the particle size classification strictly controls the distribution of pre-synthesized magnesium iron spinel particles and zircon particles to be between 0.1 mm and 1.0 mm, and the flake graphite is ground to below 200 mesh.

[0036] Preferably, the dry mixing time in step b is 2-3 minutes, and the wet mixing time is 8-12 minutes.

[0037] Preferably, the particle size of the granulated particles in step c is controlled to be between 0.2 mm and 0.8 mm.

[0038] Compared with the prior art, the advantages and positive effects of the present invention are: the automatic pouring rate reaches more than 99.4%. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the longitudinal section of the ladle nozzle structure and the high-manganese steel special diversion sand filling structure.

[0040] In the diagram: 1. Ladle nozzle seat brick; 2. Upper part of the diversion sand; 3. Lower part of the diversion sand; 4. Ladle upper nozzle; 5. Ladle bottom brick; 6, 7, 8. Ladle bottom refractory material; 9. Ladle upper slide plate; 10. Ladle lower slide plate; 11. Ladle lower nozzle. Detailed Implementation

[0041] To better understand the above-mentioned objectives, features, and advantages of the present invention, the present invention will be further described below through embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in these embodiments can be combined with each other.

[0042] Numerous specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways than those described herein, and therefore the invention is not limited to the specific embodiments disclosed in the following specification. Example 1

[0043] Reference Figure 1 This embodiment provides a method for improving the self-starting rate of steel ladle casting using special high-manganese steel diversion sand. The method includes the following steps in sequence:

[0044] 1) Three-stage cleaning for hot repair of steel ladle: Use a coarse oxygen pipe with a diameter of 25mm to clean the steel slag on the surface of the nozzle seat brick, use a fine oxygen pipe with a diameter of 8mm to clean the inside of the nozzle until the oxygen pipe stops igniting, install the slide plate and clean the fire mud a second time, shut down the mechanism and wait 45 seconds before purging again.

[0045] 2) Adding diversion sand: A gradient filling method is used, such as... Figure 1 As shown, the lower layer uses magnesium olivine sand, and the upper layer uses high-manganese steel special guide sand. The composition and mass percentage of the high-manganese steel special guide sand in this embodiment are: MnO 6%, MgO 2%, magnesium iron spinel 40%, zircon content 20%, and carbon content 5%. The upper layer of high-manganese steel special guide sand forms mushroom-shaped bulges covering the sprue seat brick 1. The particle size distribution of the high-manganese steel special guide sand in this embodiment meets the following requirements: 95% of particles are 0.2-1.0mm, 3% are fine powder <0.2mm, the moisture content is 0.3%, and the mass ratio of FeO to CrO is controlled at 0.8.

[0046] 3) Dynamic Argon Gas Regulation During Tapping: Avoiding Impact and Precise Alloying. During converter tapping, the steel flow point is controlled to avoid the guide sand filling area, preventing the molten steel from violently scouring the sand layer surface, which could lead to localized sintering or compositional changes. Alloy is added 25 seconds after tapping begins. This utilizes the initial impact force of the molten steel for preliminary stirring. Adding the alloy after a certain amount of molten steel (approximately 1 / 4 to 1 / 3) has been added to the ladle improves alloy yield and reduces direct impact on the ladle bottom.

[0047] 4) Continuous casting start-up: The slide plates (including upper slide plate 9 and lower slide plate 10) are fully opened at one time to achieve automatic start-up, with a start-up rate of 99.5%.

[0048] In this embodiment, the thickness of the high manganese steel special diversion sand filling is 200mm, accounting for about 30% of the total weight. The lower layer of magnesium olivine sand is 460mm thick, accounting for about 70% of the total weight.

[0049] The preparation method of special drainage sand for high manganese steel includes the following steps:

[0050] a. Raw material preparation and pretreatment: Take electrolytic MnO powder, high-purity MgO powder, pre-synthesized magnesium iron spinel particles, zircon particles and flake graphite that meet the requirements respectively. Crush the pre-synthesized magnesium iron spinel particles and zircon particles, strictly control the distribution of the pre-synthesized magnesium iron spinel particles and zircon particles between 0.1mm and 1.0mm, then perform particle size classification, and grind the flake graphite to below 200 mesh;

[0051] b. Ingredients and mixing: Weigh and mix the ingredients precisely according to the weight percentages described in step 2. Put all the raw materials into a high-efficiency mixer and dry mix for 2 minutes to ensure that the various powders and particles are evenly distributed. Then add 4-6% of the total weight of the raw materials as phenolic resin and wet mix for 8 minutes until all materials are evenly coated with the binder and there is no white material.

[0052] c. Granulation and curing: The mixed wet material is fed into a granulator. By controlling the granulator parameters, it is formed into approximately spherical particles. The particle size of the granulated particles is controlled between 0.2 mm and 0.8 mm. The granulated wet particles are placed in a curing chamber for heat treatment at 180°C for 4 hours to fully cure the binder and give the particles sufficient cold strength. This facilitates transportation and filling while ensuring that the particles maintain their structural integrity during the initial baking of the ladle.

[0053] d. Cooling and Packaging: After solidification, the granules are cooled and screened to remove fine powder and excessively large particles, resulting in finished high-manganese steel special guide sand. The sand is then sealed in packaging to prevent moisture absorption. Example 2

[0054] This embodiment provides a method for improving the self-starting rate of steel ladle casting using special high-manganese steel guiding sand. The method includes the following steps in sequence:

[0055] 1) Three-stage cleaning for hot repair of steel ladle: Use a coarse oxygen pipe with a diameter of 20mm to clean the steel slag on the surface of the nozzle seat brick, use a fine oxygen pipe with a diameter of 10mm to clean the inside of the nozzle until the oxygen pipe stops igniting, install the slide plate and clean the fire mud a second time, shut down the mechanism and wait 45 seconds before purging again.

[0056] 2) Adding diversion sand: A gradient filling method is used, such as... Figure 1As shown, the lower layer uses magnesium olivine sand, and the upper layer uses high-manganese steel special guide sand. The composition and mass percentage of the high-manganese steel special guide sand in this embodiment are: MnO 8%, MgO 3%, magnesium iron spinel 35%, zircon content 24%, and carbon content 3%. The upper layer of high-manganese steel special guide sand forms mushroom-shaped bulges covering the sprue seat brick 1. The particle size distribution of the high-manganese steel special guide sand in this embodiment meets the following requirements: 96% of particles are 0.2-1.0 mm, 2.5% are fine powder <0.2 mm, and the moisture content is 0.25%. Furthermore, the mass ratio of FeO to CrO is controlled at 0.9.

[0057] 3) Dynamic Argon Gas Regulation During Tapping: Avoiding Impact and Precise Alloying. During converter tapping, the steel flow point is controlled to avoid the guide sand filling area, preventing the molten steel from violently scouring the sand layer surface, which could lead to localized sintering or compositional changes. Alloy is added 25 seconds after tapping begins. This utilizes the initial impact force of the molten steel for preliminary stirring. Adding the alloy after a certain amount of molten steel (approximately 1 / 4 to 1 / 3) has been added to the ladle improves alloy yield and reduces direct impact on the ladle bottom.

[0058] 4) Continuous casting start-up: The slide plate opens fully at once, realizing automatic start-up, with a start-up rate of 99.8%.

[0059] In this embodiment, the thickness of the high manganese steel special diversion sand filling is 240mm, accounting for about 30% of the total weight. The lower layer of magnesium olivine sand is 500mm thick, accounting for about 70% of the total weight.

[0060] The preparation method of special drainage sand for high manganese steel includes the following steps:

[0061] a. Raw material preparation and pretreatment: Take electrolytic MnO powder, high-purity MgO powder, pre-synthesized magnesium iron spinel particles, zircon particles and flake graphite that meet the requirements respectively. Crush the pre-synthesized magnesium iron spinel particles and zircon particles, strictly control the distribution of the pre-synthesized magnesium iron spinel particles and zircon particles between 0.1mm and 1.0mm, then perform particle size classification, and grind the flake graphite to below 200 mesh;

[0062] b. Ingredients and mixing: Weigh and mix the ingredients precisely according to the weight percentages described in step 2. Put all the raw materials into a high-efficiency mixer and dry mix for 3 minutes to ensure that the various powders and particles are evenly distributed. Then add 4-6% of the total weight of the raw materials as phenolic resin and wet mix for 12 minutes until all materials are evenly coated with the binder and there is no white material.

[0063] c. Granulation and curing: The mixed wet material is fed into a granulator. By controlling the granulator parameters, it is formed into approximately spherical particles. The particle size of the granulated particles is controlled between 0.2 mm and 0.8 mm. The granulated wet particles are placed in a curing chamber for heat treatment at a temperature of 220°C for 2 hours to fully cure the binder, giving the particles sufficient cold strength. This facilitates transportation and filling while ensuring that the particles maintain their structural integrity during the initial baking of the ladle.

[0064] d. Cooling and Packaging: After solidification, the granules are cooled and screened to remove fine powder and excessively large particles, resulting in finished high-manganese steel special guide sand. The sand is then sealed in packaging to prevent moisture absorption. Example 3

[0065] This embodiment provides a method for improving the self-starting rate of steel ladle casting using special high-manganese steel guiding sand. The method includes the following steps in sequence:

[0066] 1) Three-stage cleaning for hot repair of steel ladle: Use a coarse oxygen pipe with a diameter of 25mm to clean the steel slag on the surface of the nozzle seat brick, use a fine oxygen pipe with a diameter of 8mm to clean the inside of the nozzle until the oxygen pipe stops igniting, install the slide plate and clean the fire mud a second time, shut down the mechanism and wait 45 seconds before purging again.

[0067] 2) Adding diversion sand: A gradient filling method is used, such as... Figure 1 As shown, the lower layer uses magnesium olivine sand, and the upper layer uses high-manganese steel special guide sand. The composition and mass percentage of the high-manganese steel special guide sand in this embodiment are: MnO 7%, MgO 2.5%, magnesium iron spinel 38%, zircon content 22.5%, and carbon content 4%. The upper layer of high-manganese steel special guide sand forms mushroom-shaped bulges covering the sprue seat brick 1. The particle size distribution of the high-manganese steel special guide sand in this embodiment meets the following requirements: 97% of particles are 0.2-1.0mm, 2% are <0.2mm fine powder, and the moisture content is 0.3%, with the FeO to CrO mass ratio controlled at 1.

[0068] 3) Dynamic Argon Gas Regulation During Tapping: Avoiding Impact and Precise Alloying. During converter tapping, the steel flow point is controlled to avoid the guide sand filling area, preventing the molten steel from violently scouring the sand layer surface, which could lead to localized sintering or compositional changes. Alloy is added 25 seconds after tapping begins. This utilizes the initial impact force of the molten steel for preliminary stirring. Adding the alloy after a certain amount of molten steel (approximately 1 / 4 to 1 / 3) has been added to the ladle improves alloy yield and reduces direct impact on the ladle bottom.

[0069] 4) Continuous casting start-up: The slide plate opens fully at one time, realizing automatic start-up, with a start-up rate of 99.9%.

[0070] In this embodiment, the thickness of the high manganese steel special diversion sand filling is 220mm, accounting for about 30% of the total weight. The lower layer of magnesium olivine sand is 480mm thick, accounting for about 70% of the total weight.

[0071] The preparation method of special drainage sand for high manganese steel includes the following steps:

[0072] a. Raw material preparation and pretreatment: Take electrolytic MnO powder, high-purity MgO powder, pre-synthesized magnesium iron spinel particles, zircon particles and flake graphite that meet the requirements respectively. Crush the pre-synthesized magnesium iron spinel particles and zircon particles, strictly control the distribution of the pre-synthesized magnesium iron spinel particles and zircon particles between 0.1mm and 1.0mm, then perform particle size classification, and grind the flake graphite to below 200 mesh;

[0073] b. Ingredients and mixing: Weigh and mix the ingredients precisely according to the weight percentages described in step 2. Put all the raw materials into a high-efficiency mixer and dry mix for 2.5 minutes to ensure that the various powders and particles are evenly distributed. Then add 4-6% of the total weight of the raw materials as phenolic resin and wet mix for 10 minutes until all materials are evenly coated with the binder and there is no white material.

[0074] c. Granulation and curing: The mixed wet material is fed into a granulator. By controlling the granulator parameters, it is formed into approximately spherical particles. The particle size of the granulated particles is controlled between 0.2 mm and 0.8 mm. The granulated wet particles are placed in a curing chamber for heat treatment at a temperature of 220°C for 3 hours to fully cure the binder, giving the particles sufficient cold strength. This facilitates transportation and filling while ensuring that the particles maintain their structural integrity during the initial baking of the ladle.

[0075] d. Cooling and Packaging: After solidification, the granules are cooled and screened to remove fine powder and excessively large particles, resulting in finished high-manganese steel special guide sand. The sand is then sealed in packaging to prevent moisture absorption.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for improving the tapping rate of a ladle by using high manganese steel special sand, characterized in that, The method includes the following steps in sequence: 1) Three-stage cleaning for hot repair of steel ladle: Use a coarse oxygen pipe to clean the steel slag on the surface of the nozzle seat brick, use a fine oxygen pipe to clean the inside of the nozzle until the oxygen pipe stops igniting, install the slide plate and clean the fire mud a second time, shut down the mechanism and wait for the first time before purging again. 2) Adding diversion sand: A gradient filling method is adopted, with magnesium olivine sand in the lower layer and high manganese steel special diversion sand in the upper layer. The composition and mass percentage of the high manganese steel special diversion sand are: MnO content 6-8%, MgO content 2-3%, magnesium iron spinel 35-40%, zircon content 20-24%, carbon content 3-5%; the upper layer of high manganese steel special diversion sand forms a mushroom-shaped bulge covering the sprue seat brick; The coarse oxygen tube refers to an oxygen tube with a diameter Φ≥20mm, and the fine oxygen tube refers to an oxygen tube with a diameter Φ≤8mm. The particle size distribution of the special high-manganese steel guiding sand meets the following requirements: ≥95% of particles with a diameter of 0.2-1.0mm, ≤3% of fine powder with a diameter of <0.2mm, and ≤0.3% of moisture content. The mass ratio of FeO to CrO is controlled between 0.8 and 1.

0. The upper layer of the diversion sand has a filling thickness of 200-240mm, and the lower layer has a filling thickness of 460-500mm. The "fast filling and slow lifting" method is adopted: the filling cylinder is inserted into the bottom of the water inlet for rapid filling, and the cylinder is slowly lifted to avoid stratification.

2. The method for improving the self-starting rate of steel ladle casting using special high-manganese steel diversion sand according to claim 1, characterized in that: The method for preparing special diversion sand for high manganese steel includes the following steps in sequence: a. Raw material preparation and pretreatment: Take electrolytic MnO powder, high-purity MgO powder, pre-synthesized magnesium iron spinel particles, zircon particles and flake graphite that meet the requirements respectively. Crush the pre-synthesized magnesium iron spinel particles and zircon particles, then classify them by particle size, and grind the flake graphite. b. Ingredients and mixing: Weigh and mix the ingredients precisely according to the weight percentages described in step 2. Put all the raw materials into a high-efficiency mixing mill and dry mix them first to ensure that the various powders and particles are evenly distributed. Then add a composite binder accounting for 4-6% of the total weight of the raw materials and wet mix them until all materials are evenly coated with the binder and there is no white material. c. Granulation and curing: The mixed wet material is fed into the granulator. By controlling the parameters of the granulator, it is formed into approximately spherical particles. The granulated wet particles are placed in the curing chamber for heat treatment to fully cure the binder and give the particles sufficient cold strength. This facilitates transportation and filling while ensuring that the particles maintain their structural integrity in the early stage of ladle baking. d. Cooling and Packaging: After solidification, the granules are cooled and screened to remove fine powder and excessively large particles, resulting in finished high-manganese steel special guide sand. The sand is then sealed in packaging to prevent moisture absorption.

3. The method for improving the self-starting rate of steel ladle casting using special high-manganese steel diversion sand according to claim 2, characterized in that: The composite binder can be a phenolic resin or a sugar alcohol liquid.

4. The method for improving the self-casting rate of steel ladles using special high-manganese steel diversion sand according to claim 2, characterized in that: The heat treatment in step c is performed at a temperature of 180-220℃ for 2-4 hours.

5. The method for improving the self-casting rate of steel ladles using special high-manganese steel diversion sand according to claim 2, characterized in that: The particle size classification described in step a strictly controls the distribution of pre-synthesized magnesium iron spinel particles and zircon particles between 0.1 mm and 1.0 mm, and the flake graphite is ground to below 200 mesh.

6. The method for improving the self-starting rate of steel ladle casting using special high-manganese steel diversion sand according to claim 2, characterized in that: The dry mixing time in step b is 2-3 minutes, and the wet mixing time is 8-12 minutes.

7. The method for improving the self-casting rate of steel ladles using special high-manganese steel diversion sand according to claim 2, characterized in that: In step c, the particle size of the granulated particles is controlled to be between 0.2 mm and 0.8 mm.

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