A modified magnesia, a converter slide block, and a method for preparing them.

Abstract

This invention discloses a modified magnesia, a converter slide gate brick, and their preparation methods, belonging to the field of refractory materials technology. The composition and weight percentage of the reinforced converter slide gate brick are as follows: 60%-64% modified magnesia, 36%-40% co-ground powder, totaling 100%; and 4%-5% high-temperature binder. The modified magnesia is obtained by adding additives to lightly calcined magnesia powder and reacting them at high temperature. The resulting modified magnesia has a large grain size and good resistance to slag penetration. Introducing this modified magnesia into the slide gate brick results in slide gate bricks with good high-temperature resistance, slag resistance, and spalling resistance.

Description

Technical Field

[0001] This invention belongs to the field of refractory materials technology, and more specifically, relates to a modified magnesia, a converter slide block, and a method for preparing them. Background Technology

[0002] In the process of converter and converter steelmaking, aluminum-carbon converter slide plates are currently widely used. However, the use of aluminum-carbon will affect the purity of molten steel due to the introduction of carbon, and the cost is also relatively high. This product improves the cleanliness of molten steel by decarbonizing the slide plate, and at the same time provides a high-performance reinforced converter slide plate brick.

[0003] A search revealed that patent CN111689766A discloses a high-strength 310 drain outlet brick. This drain outlet brick, by weight, is mainly composed of the following raw materials: 30-50 parts of homogenized bauxite clinker (70% ≤ Al2O3 ≤ 90%), 15-25 parts of corundum, 5-15 parts of mullite particles (70% ≤ Al2O3 ≤ 90% and Fe2O3 ≤ 2%), 5-10 parts of calcined bauxite (45% ≤ Al2O3 ≤ 80% and Fe2O3 ≤ 1%), 1-10 parts of lightly calcined magnesia powder, and 5-15 parts of white clay (34% ≤ Al2O3 ≤ 60% and Fe2O3 ≤ 2%). While this patent achieves carbon-free sliding plate construction, the 90% bauxite raw material constitutes a large proportion and is classified as an aluminum refractory material. The white clay used (5-15%) contains a large amount of impurities and other components, resulting in low purity, poor erosion resistance, and poor slag resistance, making it unsuitable for use in converters.

[0004] Using magnesia as a raw material can significantly reduce costs. For example, patent CN111960805A discloses a thermal shock magnesia sliding plate brick. By weight percentage, the raw material composition is: 55%-70% modified magnesia particles, 30%-45% fine magnesia powder, and 3%-5% pulp waste liquor. The preparation method is as follows: First, α-Al2O3 micropowder is prepared by using a saturated solution of aluminum chloride or aluminum sulfate as a binder to coat the modified magnesia particles. Each component is weighed and mixed for 0.5 hours. Then, the mixture is formed using a press selected according to the single weight of the sliding plate. The green body is dried at 110℃ for 24 hours, and then fired in a kiln at 1500℃ for 8 hours. After firing, the green body undergoes processes such as hooping, steel shell bonding, grinding, coating, finishing, and acceptance before being stored in a warehouse. However, the binder used in this patent is pulp waste liquor, which has low high-temperature bonding strength, and the high-temperature firing process results in high energy consumption and costs.

[0005] Patent CN113968724A discloses a metal-modified magnesia, a low-carbon converter magnesia slide plate, and their preparation methods, belonging to the field of refractory materials. The composition and weight percentage of the low-carbon converter magnesia slide plate with added metal-modified magnesia are as follows: 40%-55% metal-modified magnesia, 10%-25% heavy calcium hexaaluminate, 30%-35% co-milled powder, totaling 100%; with an added 3.5%-4.5% phenolic resin binder.

[0006] Patent CN116283315A discloses a carbon-free pressurized spinel sliding block and its preparation method, belonging to the field of refractory materials technology. The sliding block is composed of the following composition by mass percentage: 57-65% sintered spinel particles, 1%-5% silicon carbide particles, 35%-40% co-milled powder, totaling 100%, plus 3%-5% binder. The binder is obtained by mixing polysaccharide and brine in a 1:2 ratio. The co-milled powder is prepared by uniformly mixing 6%-17% sintered spinel fine powder, 5%-10% fused magnesia powder, 10-15% metallic aluminum powder, 2%-6% α-Al₂O₃ micro powder, and 1%-3% metallic silicon powder.

[0007] However, the magnesia used in the aforementioned patent is ordinary fused magnesia, which has low slag resistance and erosion resistance. Summary of the Invention

[0008] 1. The problem to be solved

[0009] To address the issue of low slag resistance and erosion resistance of magnesia used in existing sliding bricks, this invention provides a modified magnesia and its preparation method. This modified magnesia has higher crystallinity and exhibits better slag resistance and erosion resistance.

[0010] The present invention also provides a sliding plate brick with the addition of the modified magnesia and a method for preparing the same, the sliding plate brick having high slag resistance and erosion resistance.

[0011] 2. Technical Solution

[0012] To solve the above problems, the technical solution adopted by the present invention is as follows:

[0013] A modified magnesia, the preparation method of which includes the following steps:

[0014] Additives are added to lightly calcined magnesium oxide powder, and after thorough mixing, the mixture is put into an electric arc furnace for smelting. The reaction is carried out for 5-12 hours. After the reaction is complete, the mixture is cooled to obtain modified magnesia with ultra-large crystals.

[0015] The additives are 0.01%-2% chromium oxide and 0.2%-2% aluminum oxide, which are smelted at a temperature above 2750°C. By introducing the additives, the melting point is lowered, and the viscosity and composition of the liquid phase involved in the reaction are changed. Finally, a solid solution is formed between Cr2O3, Al2O3 and magnesia, which causes magnesia lattice distortion and promotes the growth of magnesia grains.

[0016] Furthermore, to avoid the influence of impurities in chromium oxide and aluminum oxide on grain growth, chromium oxide and aluminum oxide are pretreated by acid washing and soaking to remove silicon and calcium impurities from large crystalline magnesia.

[0017] Preferably, soaking in 50%-70% hydrochloric acid for 10-15 hours and adjusting the pH to 6.0-6.5 is used to remove silicon and calcium impurities from large crystalline magnesia. Silicon mainly precipitates in the form of silicic acid, and calcium is removed in the form of CaCl2. However, the pH should not be too low, as excessive acidity will corrode the magnesia particles, resulting in too many pores on the particle surface and a loose structure. If added to the sliding brick, it will affect the strength of the sliding brick.

[0018] By adding fluxing agents to promote grain growth and further removing impurities that affect crystallinity, modified magnesia with large grain size, few grain boundaries, high degree of direct bonding between grains, and few grain boundary impurities is obtained. The resulting modified magnesia has a grain size of 5000-7000 μm, which is much larger than that of conventional fused magnesia, and a density of 3.48-3.84 g / cm³. 3 It has a melting point of 2860-2950℃ and a purity greater than 98.5%. The slag has poor wettability on large-crystal modified magnesia, thus it has good resistance to slag penetration.

[0019] When modified magnesia is added to the slide block, it combines with the α-Al2O3 in the slide block to form magnesium aluminum spinel. Compared with magnesium aluminum spinel formed by small-particle-size fused magnesia, it has excellent slag resistance. The principle is that magnesium aluminum spinel is formed by the reaction of the MgO-Al2O3 binary system. It has a high melting point, few pores, and a small coefficient of thermal expansion. The product has small changes in size and volume expansion when heated, and low thermal conductivity, which slows down the reaction rate between slag and product. Therefore, the slide block has excellent slag resistance and corrosion resistance, as well as good thermal shock resistance.

[0020] The modified magnesia also contains magnesium aluminum spinel formed by the reaction with alumina. The magnesium aluminum spinel exists between the grain boundaries of the modified magnesia and the content of the magnesium aluminum spinel is 0.01%-0.1%.

[0021] The modified magnesia was finally crushed and screened using mechanical crushing and air jet milling to obtain modified magnesia particles and fine powder of different particle sizes.

[0022] A converter slide block brick, comprising the following components and weight percentages: 60%-64% modified magnesia particles, 36%-40% co-ground powder, totaling 100%; and 4%-5% high-temperature binder. The co-ground powder is prepared by uniformly mixing 10%-18% modified magnesia fine powder, 7%-13% α-Al₂O₃ micro powder, 8%-10% zircon fine powder, and 5% metallic silicon powder.

[0023] Preferably, the modified magnesia particles have a particle size of (5-3, 3-1, 1-0) mm, and the weight percentage of each particle size is as follows: 15% modified magnesia particles with a particle size of 5-3 mm, 30% modified magnesia particles with a particle size of 3-1 mm, and 15%-19% modified magnesia particles with a particle size of 1-0 mm; the chemical composition and content of the modified magnesia particles are as follows: 98.65% MgO, 0.80% CaO, 0.35% SiO2, 0.11% Fe2O3, and 0.09% Al2O3.

[0024] Preferably, the modified magnesia fine powder has a particle size of 325 mesh and a weight percentage of 10%-18%. The chemical composition and content of the modified magnesia fine powder are as follows: MgO content is 98.65%, CaO content is 0.80%, SiO2 content is 0.35%, Fe2O3 content is 0.11%, and Al2O3 content is 0.09%.

[0025] Preferably, the α-Al₂O₃ micropowder has a particle size of 0-2 μm; the α-Al₂O₃ micropowder contains: Al₂O₃ content ≥99.0%, SiO₂ content ≤0.1%, Fe₂O₃ content ≤0.08%, and Na₂O+K₂O content ≤0.3%. The addition amount of α-Al₂O₃ micropowder is 7%-13%, forming a liquid phase of 9%-17% at 1480℃, increasing density and further improving the slag corrosion resistance of the converter slide block.

[0026] Preferably, the zircon fine powder contains: 66.25% ZrO2, 32.50% SiO2, 0.33% TiO2, 0.37% Al2O3, 0.16% Fe2O3, 0.05% CaO, 0.02% MgO, 0.01% Na2O, and 0.01% K2O; the particle size of the zircon fine powder is 325 mesh.

[0027] Preferably, the silicon metal powder contains: 98.6% Si, 0.54% Fe, 0.49% Al, and 0.36% Ca; and the particle size of the silicon metal powder is 325 mesh.

[0028] Currently, the sliding plate material used in ordinary converter sliding mechanisms is aluminum-carbon. However, when smelting clean steel and stainless steel, which require high carbon content, ordinary aluminum-carbon sliding plate bricks cannot meet the technical requirements of steel mills regarding carbon content due to the introduction of graphite carbon and pitch carbon. Furthermore, while the main components of aluminum-carbon sliding plate bricks are alumina, metallic aluminum, carbon black, graphite, and other aluminum-carbon materials, which can meet the requirements for smelting ordinary carbon steel, they cannot meet the rapidly growing requirements for clean steel and special steel production, and their resistance to alkaline steel slag erosion and corrosion is poor.

[0029] Therefore, this invention starts with decarburization and uses modified magnesia raw materials with superior erosion resistance, high refractoriness, and strong slag corrosion resistance to form a brand-new clean steel slide plate material system for converters, in order to meet the requirements of steelmaking cleanliness and high-quality steel grades.

[0030] Considering that the modified magnesia in this application is electrofused macrocrystalline magnesia, which is larger in size, compared to smaller electrofused magnesia particles that are more easily adhered and bonded together, the larger crystals of electrofused magnesia are more likely to detach from the sliding plate bricks during use and separate from the other components. To ensure the stability of the sliding plate bricks during high-temperature use, this application uses a binder with higher thermal stability to bind the various components of the sliding plate bricks together. The high-temperature binder is a modified thermosetting resin with a stable structure. Even as the temperature rises and other substances decompose, oxidize, or evaporate, it still maintains its basic molecular structure. Its decomposition temperature reaches 250°C, which can improve the high-temperature performance and service stability of the product.

[0031] Its molecular formula is R 1-3 SiO 0.5-2 Where R is one or more of methyl, phenyl, and methylphenyl. This high-temperature binder is a highly cross-linked semi-inorganic polymer with Si-O-Si main chain and organic groups attached to silicon atoms. It is made by hydrolyzing multifunctional organosilanes to produce silicone resin prepolymers. The prepolymers are further cross-linked under heating or catalysis to form insoluble and infusible solid silicone resins with a three-dimensional network structure.

[0032] The preparation method of the high-temperature binder includes the following steps: under acidic conditions with a pH of 2-3, 6%-8% of methylphenyl organosilicon resin is added, and the resin is hydrolyzed into hydroxyl-terminated silicone resin through reaction for 2 hours. Then, phenol and formaldehyde are added to catalyze the hydrolysis of silicone resin and the synthesis of phenolic resin, and the reaction time is 2 hours. The hydroxyl-terminated silicone resin and the hydroxymethyl group in the phenolic resin are condensed to form organosilicon-modified phenolic resin.

[0033] Among them, acids are commonly used as catalysts, such as oxalic acid, hydrochloric acid, sulfuric acid, phosphoric acid, and benzenesulfonic acid. Oxalic acid is preferred to reduce the introduction of impurity ions.

[0034] The addition of phenol is 51%-52%, and the addition of formaldehyde is 36%-38%, with the molar ratio of phenol to formaldehyde controlled to be less than 1. When the molar ratio of phenol to formaldehyde is controlled to be less than 1, a certain amount of polyhydroxymethylphenol is formed. The linear resin formed by the further reaction of polyhydroxymethylphenol forms a three-dimensional resin structure during gluing. When the molar ratio of phenol to formaldehyde is greater than 1, there is not enough aldehyde to form polyhydroxymethylphenol, and the linear resin formed by further condensation cannot further develop into a three-dimensional structure, thus resulting in a thermoplastic resin.

[0035] The obtained high-temperature binder is organosilicon-modified phenolic resin. The thermal decomposition temperature of the modified phenolic resin increases with the increase of organosilicon resin content (ranging from 6% to 8%), and its thermal stability also increases. This is because: on the one hand, during the synthesis process, a condensation reaction occurs between Si-OH and the phenolic hydroxyl groups of the phenolic resin, resulting in strong binding force and greatly enhancing the binding ability of the cross-linked network of the system; on the other hand, the organosilicon resin contains a Si-O-Si structure, and the bond energy of the Si-O bond (422.5 kJ / mol) is much greater than that of the CO bond (344.4 kJ / mol). Introducing Si-O bonds into the phenolic resin, with the increase of Si-O-Si structure content in the system, improves the heat resistance of the modified phenolic resin.

[0036] Among them, the zircon fine powder contains ZrO2, which reacts with CaO in the components at high temperature to form CaZrO. 3和 The formation of these new phases, CS3, can activate the crystal lattice and promote grain growth. Zircon has a high melting point of 2430℃ and belongs to the tetragonal crystal system. Its crystals are tetragonal bipyramidal, columnar, and tabular. When heated in air, it is not easily corroded by oxidizing gases, has a small coefficient of thermal expansion, good thermal shock resistance, good stability, strong corrosion resistance, and does not stick to molten steel. At the same time, the introduction of zircon improves the hydration resistance of the product and minimizes the hydration weight gain.

[0037] The melting point of MgO in modified magnesia is 2800℃, while the melting point of CaO in zircon sand is 2570℃. The eutectic point of MgO and CaO is high at 2730℃, thus effectively improving the high-temperature resistance of sliding bricks.

[0038] During use, the sliding block comes into contact with the slag, and CaO reacts with the slag components to generate a high-temperature mineral phase containing 2CaO SiO2 (melting point 2136℃) and 3CaO SiO2 (melting point 1900℃), which increases the viscosity of the slag and slows down the erosion of refractory materials.

[0039] The ZrO2 introduced into zircon can effectively absorb CaO in converter slag, forming a high-melting-point CaZrO3 solid phase that blocks the pores, preventing further slag penetration and effectively reducing the decomposition effect of CaO on spinel and the erosion effect of CaO, SiO2, etc. on the main crystalline phase periclase. At the same time, the introduction of ZrO2 can promote sintering, increase the direct bonding rate of high-temperature solid phase, and minimize the flexural strength loss rate of MgO-CaO materials. After the addition of zircon, periclase grains develop larger, and with the formation of CaZrO3, there is volume expansion, resulting in radial microcracks around the CaZrO3 particles. The presence of these microcracks increases the energy dissipation mechanism, prevents crack propagation, and improves the thermal shock stability of the sliding brick.

[0040] The slide block bricks made using this component exhibit strong resistance to chemical erosion and penetration of slag during use. The CaO in the slide block has high creep resistance at high temperatures, which can buffer the thermal stress generated inside the brick due to rapid temperature changes and inhibit the generation and propagation of cracks inside the slide block. On the other hand, the CaO in the slide block bricks reacts with SiO2 in the slag to form high-melting-point minerals, which increases the viscosity of the slag and improves the resistance to structural spalling of the reinforced converter slide block bricks.

[0041] Another object of the present invention is to provide a method for preparing converter slide block, which includes the following steps:

[0042] Step 1: Preparation of co-milled powder: Modified magnesia fine powder, α-Al2O3 micro powder, zircon fine powder and metallic silicon powder are mixed evenly according to weight percentage to obtain co-milled powder;

[0043] Step 2, Granular Material Batching: Mix modified magnesia particles with a particle size of 5-3mm, 3-1mm, and 1-0mm uniformly by weight percentage to obtain granular material batching.

[0044] Step 3, Mixing: Dry mix the granules with a wet mill for 2-3 minutes, then slowly add the high-temperature binder and wet mix for 5-8 minutes. Finally, add the co-milling powder and mix for 50-60 minutes to obtain the mixture.

[0045] Step 4: Molding: The mixture is pressed into semi-finished brick blanks on a 630t electric screw press.

[0046] Step 5, Drying: After the green body is naturally air-dried for 8 hours, it is placed in a tunnel natural gas drying kiln and dried according to the set curve. The initial temperature of the kiln is 30℃. The temperature is increased from 30℃ to 80℃ within 4 hours and held for 1 hour. Then, the temperature is increased from 80℃ to 120℃ within 4 hours and held for 1 hour. Then, the temperature is increased from 120℃ to 150℃ within 3 hours and held for 1 hour. Then, the temperature is increased from 150℃ to 180℃ within 3 hours and held for 1 hour. Then, the temperature is increased from 180℃ to 210℃ within 3 hours and held for 16 hours. The total drying time is 37 hours. After the product is removed from the kiln, it is inspected, and products that meet the size and appearance requirements are selected to proceed to the next process.

[0047] Step Six: Shelling: After drying and passing inspection, shell the product. Apply an appropriate amount of fire clay to the outer wall of the slide plate (enough to squeeze fire clay out from both the top and bottom of the slide plate under pressure). Place the steel shell on top, then invert the slide plate into the fixture and press it to the designated position. Remove the slide plate. Ensure that fire clay is squeezed out from both the top and bottom of the slide plate after pressing. Use a tool to clean the overflowing fire clay from the upward-facing part of the slide plate, then remove the slide plate from the fixture. After removing the slide plate, place it with the top opening facing down to clean the remaining fire clay, ensuring the slide plate remains clean during cleaning. Perform an initial inspection of the product. If the inspection is passed, place the slide plate with the larger end facing down on the frame. If the inspection fails, the operator needs to adjust the limit blocks or gently tap the steel shell with a tool to make it pass.

[0048] Step 7, Drying: After the shell is applied, the slide plate is naturally cured at room temperature for 4-8 hours before drying. The product is currently dried using a natural gas tunnel drying kiln. The drying temperature curve is as follows: the temperature is increased from 30℃ to 80℃ in 1 hour and held for 1 hour → the temperature is increased from 80℃ to 120℃ in 1 hour and held for 1 hour → the temperature is increased from 120℃ to 150℃ in 1 hour and held for 8 hours. The total drying time is 13 hours.

[0049] Step 8: Packaging: After drying, remove from the kiln and let it air dry to room temperature. Check the size and appearance according to the drawing requirements and appearance standards, and then pack it into boxes.

[0050] The enhanced converter slide block production process of this invention consists of eight steps. Detailed operating procedures and process parameter requirements have been formulated for each step of the product production. In particular, the drying process specifies a natural drying time of 8 hours to allow some moisture to drain naturally first, preventing cracking of the products caused by direct drying in the kiln. The drying temperature curve requirements, especially the control of the heating rate in the low-temperature stage, prevent excessive heating and cracking of the products. This ensures that the production process is under control and guarantees the effective implementation of the technical solution.

[0051] 3. Beneficial effects

[0052] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0053] (1) The modified magnesia prepared by this invention has a grain size of 5000-7000 μm and a density of 3.48-3.84 g / cm³. 3 With a melting point of 2860-2950℃, the slag has poor wettability on large-crystal modified magnesia, thus exhibiting good resistance to slag penetration.

[0054] (2) The present invention uses a modified thermosetting resin with higher thermal stability as a binder. Its structure is stable and its decomposition temperature reaches 250℃, which can improve the high temperature performance and use stability of the product.

[0055] (3) Modified magnesia is added to the sliding plate brick of the present invention, and the resulting sliding plate brick has excellent slag resistance and corrosion resistance, and good thermal shock resistance. Attached Figure Description

[0056] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless specifically indicated, these drawings are intended only to conceptually illustrate the structural construction described herein and are not necessarily drawn to scale.

[0057] Figure 1 This is an electron microscope image of the modified magnesia of this application;

[0058] Figure 2 This is a photo of the skateboard brick before use in this application;

[0059] Figure 3 Photos of the skateboard bricks after use in this application;

[0060] Figure 4 Photos of existing aluminum-carbon material skateboard bricks after use. Detailed Implementation

[0061] The following detailed description of exemplary embodiments of the invention is taken with reference to the accompanying drawings, which form part of the description and illustrate exemplary embodiments in which the invention may be practiced. While these exemplary embodiments have been described in sufficient detail to enable those skilled in the art to practice the invention, it should be understood that other embodiments may be implemented and various changes may be made to the invention without departing from the spirit and scope thereof. The more detailed description of embodiments of the invention below is not intended to limit the scope of the claimed invention, but is merely illustrative and not restrictive of the description of the features and characteristics of the invention, to suggest the best mode for carrying out the invention, and is sufficient to enable those skilled in the art to practice the invention. Therefore, the scope of the invention is defined only by the appended claims.

[0062] Unless otherwise specified, all materials used in this invention are commercially available products.

[0063] Example 1

[0064] A modified magnesia, the preparation method of which includes the following steps:

[0065] Additives are added to lightly calcined magnesium oxide powder, and after thorough mixing, the mixture is put into an electric arc furnace and smelted at 2750℃ for 5-12 hours. After the reaction is complete, it is cooled to obtain modified magnesia with ultra-large crystals.

[0066] The additives are 0.01%-2% chromium oxide and 0.2%-2% aluminum oxide.

[0067] Furthermore, to avoid the influence of impurities in chromium oxide and aluminum oxide on grain growth, chromium oxide and aluminum oxide are pretreated by soaking in 50%-70% hydrochloric acid for 10-15 hours and adjusting the pH to 6.0-6.5. In the example, 60% hydrochloric acid is used for soaking for 12 hours and the pH is adjusted to 6.5.

[0068] Remove silicon and calcium impurities from large crystalline magnesia.

[0069] The modified magnesia obtained had a grain size of 5000-7000 μm and a density of 3.48 g / cm³. 3 It has a melting point of 2800℃, a purity of over 98.5%, and good resistance to slag penetration.

[0070] The preparation process and parameters of the modified magnesia are shown in Table 1. The electron micrographs of the obtained modified magnesia are shown below. Figure 1 As shown in the figure, the marked area is modified magnesia, with a size of 5000-7000μm.

[0071] Example 2

[0072] The preparation process and parameters of the modified magnesia in this embodiment are shown in Table 1.

[0073] Example 3

[0074] The preparation process and parameters of the modified magnesia in this embodiment are shown in Table 1.

[0075] Example 4

[0076] The preparation process and parameters of the modified magnesia in this embodiment are shown in Table 1.

[0077] Comparative Example 1

[0078] The modified magnesia of Comparative Example 1 was prepared using chromium oxide and aluminum oxide without acid leaching treatment. The preparation process and parameters of the magnesia are shown in Table 1.

[0079] Comparative Example 2

[0080] The magnesia in Comparative Example 2 was not modified with chromium oxide and aluminum oxide, and its parameters are shown in Table 1.

[0081] Table 1. Modified magnesia and its preparation process parameters in the embodiments and comparative examples of the present invention.

[0082]

[0083] As shown in Table 1, the modified magnesia grains obtained are much larger than those of the unmodified magnesia grains, exhibiting higher density and higher melting point, with a purity higher than 98.5%.

[0084] Example 5

[0085] The preparation method of the high-temperature binder includes the following steps:

[0086] In an oxalic acid solution with an acidic pH of 2-3, 6%-8% of methylphenyl organosilicon resin is added, which hydrolyzes to form hydroxyl-terminated silicone resin over 2 hours. Phenol and formaldehyde are then added, catalyzing both the acid-catalyzed hydrolysis of the silicone resin and the synthesis of phenolic resin over 2 hours. The hydroxyl-terminated silicone resin and the hydroxymethyl groups in the phenolic resin undergo condensation to form organosilicon-modified phenolic resin. The preparation process and parameters of the modified magnesia are shown in Table 2.

[0087] Example 6

[0088] The preparation process and parameters of the high-temperature binder and modified magnesia in this embodiment are shown in Table 2.

[0089] Example 7

[0090] The preparation process and parameters of the high-temperature binder and modified magnesia in this embodiment are shown in Table 2.

[0091] Example 8

[0092] The preparation process and parameters of the high-temperature binder and modified magnesia in this embodiment are shown in Table 2.

[0093] Table 2. High-temperature binders and their preparation process parameters in the embodiments and comparative examples of the present invention.

[0094] Example 5 Example 6 Example 7 Example 8 pH 2.2 2.4 2.6 2.9 Methylphenyl silicone resin, % 6 6.5 7 7.8 phenol,% 51.71 51.58 51.46 51.26 formaldehyde,% 37.13 37.04 36.95 36.81 Hydrolysis time, h 2 2 2 2 Reaction time, h 1 1 1 1 Organosilicon modified phenolic resin <![CDATA[R3SiO 1 / 2 ]]> <![CDATA[R2SiO]]> <![CDATA[R3SiO 3 / 2 ]]> <![CDATA[R3SiO2]]>

[0095] Example 9

[0096] A converter slide block, comprising the following components and weight percentages: 64% modified magnesia, 36% co-milled powder, totaling 100%; plus 5% high-temperature binder. The co-milled powder is prepared by uniformly mixing 10% modified magnesia fine powder, 13% α-Al₂O₃ micro powder, 8% zircon fine powder, and 5% metallic silicon powder.

[0097] The modified magnesia particles and modified magnesia fine powder are electrofused sintered stable magnesia raw materials.

[0098] The modified magnesia particles have a particle size of (5-3, 3-1, 1-0) mm, and the weight percentage of each particle size is as follows: 15% modified magnesia particles with a particle size of 5-3 mm, 30% modified magnesia particles with a particle size of 3-1 mm, and 15%-19% modified magnesia particles with a particle size of 1-0 mm. The chemical composition and content of the modified magnesia particles are as follows: MgO content is 98.65%, CaO content is 0.80%, SiO2 content is 0.35%, Fe2O3 content is 0.11%, and Al2O3 content is 0.09%.

[0099] The modified magnesia fine powder has a particle size of 325 mesh and a weight percentage of 10%-18%. The chemical composition and content of the modified magnesia fine powder are as follows: MgO content is 98.65%, CaO content is 0.80%, SiO2 content is 0.35%, Fe2O3 content is 0.11%, and Al2O3 content is 0.09%.

[0100] The α-Al2O3 micro powder has a particle size of 0-2 μm; the α-Al2O3 micro powder contains: Al2O3 content ≥99.0%, SiO2 content ≤0.1%, Fe2O3 content ≤0.08%, and Na2O+K2O content ≤0.3%.

[0101] The zircon fine powder contains: 66.25% ZrO2, 32.50% SiO2, 0.33% TiO2, 0.37% Al2O3, 0.16% Fe2O3, 0.05% CaO, 0.02% MgO, 0.01% Na2O, and 0.01% K2O; the particle size of the zircon fine powder is 325 mesh.

[0102] The silicon metal powder contains 98.6% Si, 0.54% Fe, 0.49% Al, and 0.36% Ca; the particle size of the silicon metal powder is 325 mesh.

[0103] The preparation method of the above-mentioned enhanced converter slide gate brick includes the following steps:

[0104] Step 1: Preparation of co-milled powder: Modified magnesia fine powder, α-Al2O3 micro powder, zircon fine powder and metallic silicon powder are mixed evenly according to weight percentage to obtain co-milled powder;

[0105] Step 2, Granular Material Batching: Mix modified magnesia particles with a particle size of 5-3mm, 3-1mm, and 1-0mm uniformly by weight percentage to obtain granular material batching.

[0106] Step 3, Mixing: Dry mix the granules with a wet mill for 2-3 minutes, then slowly add the high-temperature binder and wet mix for 5-8 minutes. Finally, add the co-milling powder and mix for 50-60 minutes to obtain the mixture.

[0107] Step 4: Molding: The mixture is pressed into semi-finished brick blanks on a 630t electric screw press.

[0108] Step 5, Drying: After the green body is naturally air-dried for 8 hours, it is placed in a tunnel natural gas drying kiln and dried according to the set curve. The initial temperature of the kiln is 30℃. The temperature is increased from 30℃ to 80℃ within 4 hours and held for 1 hour. Then, the temperature is increased from 80℃ to 120℃ within 4 hours and held for 1 hour. Then, the temperature is increased from 120℃ to 150℃ within 3 hours and held for 1 hour. Then, the temperature is increased from 150℃ to 180℃ within 3 hours and held for 1 hour. Then, the temperature is increased from 180℃ to 210℃ within 3 hours and held for 16 hours. The total drying time is 37 hours. After the product is removed from the kiln, it is inspected, and products that meet the size and appearance requirements are selected to proceed to the next process.

[0109] Step Six: Shelling: After drying and passing inspection, shell the product. Apply an appropriate amount of fire clay to the outer wall of the slide plate (enough to squeeze fire clay out from both the top and bottom of the slide plate under pressure). Place the steel shell on top, then invert the slide plate into the fixture and press it to the designated position. Remove the slide plate. Ensure that fire clay is squeezed out from both the top and bottom of the slide plate after pressing. Use a tool to clean the overflowing fire clay from the upward-facing part of the slide plate, then remove the slide plate from the fixture. After removing the slide plate, place it with the top opening facing down to clean the remaining fire clay, ensuring the slide plate remains clean during cleaning. Perform an initial inspection of the product. If the inspection is passed, place the slide plate with the larger end facing down on the frame. If the inspection fails, the operator needs to adjust the limit blocks or gently tap the steel shell with a tool to make it pass.

[0110] Step 7, Drying: After the shell is applied, the slide plate is naturally cured at room temperature for 4-8 hours before drying. The product is currently dried using a natural gas tunnel drying kiln. The drying temperature curve is as follows: the temperature is increased from 30℃ to 80℃ in 1 hour and held for 1 hour → the temperature is increased from 80℃ to 120℃ in 1 hour and held for 1 hour → the temperature is increased from 120℃ to 150℃ in 1 hour and held for 8 hours. The total drying time is 13 hours.

[0111] Step 8, Packaging: After drying, remove from the kiln and let it air dry to room temperature. Check the dimensions and appearance according to the drawing requirements and appearance standards, and then pack it into boxes.

[0112] Example 10

[0113] The converter slide block of this embodiment has the following composition and weight percentage as shown in Table 3. The modified magnesia is the modified magnesia prepared in Example 3 of Table 1, and the high-temperature binder is the high-temperature binder prepared in Example 7 of Table 2. The preparation method is the same as in Example 9.

[0114] Example 11

[0115] The converter slide block of this embodiment has the following composition and weight percentage as shown in Table 3. The modified magnesia is the modified magnesia prepared in Example 3 of Table 1, and the high-temperature binder is the high-temperature binder prepared in Example 7 of Table 2. The preparation method is the same as in Example 9.

[0116] Example 12

[0117] The converter slide block of this embodiment has the following composition and weight percentage as shown in Table 3. The modified magnesia is the modified magnesia prepared in Example 3 of Table 1, and the high-temperature binder is the high-temperature binder prepared in Example 7 of Table 2. The preparation method is the same as in Example 9.

[0118] Comparative Example 3

[0119] The converter slide block of Comparative Example 3 has the following composition and weight percentage as shown in Table 3, and uses unmodified fused magnesia. The preparation method of the slide block is as described in Example 9.

[0120] Comparative Example 4

[0121] The converter slide block of Comparative Example 4 has the following composition and weight percentage as shown in Table 3, using unmodified phenolic resin. The preparation method of the slide block is as described in Example 9.

[0122] Comparative Example 5

[0123] The converter slide block of Comparative Example 5 is composed of unmodified fused magnesia and unmodified phenolic resin according to the formula shown in Table 3. The preparation method of the slide block is as described in Example 9.

[0124] Table 3. Composition and percentage of the sliding bricks in each embodiment and comparative example of the present invention.

[0125]

[0126] The carbon-free magnesium dolomite converter slide plate was prepared using the above embodiments.

[0127] Table 4 shows the physical and chemical properties and average service life parameters of the enhanced converter slide plate bricks obtained in Examples 9-12 above and the existing alumina-carbon converter slide plates.

[0128] Table 4. Physicochemical properties and average service life parameters of the enhanced converter slide block obtained in Examples 9-12 and the existing alumina-carbon converter slide block.

[0129]

[0130] Table 4 shows that the reinforced converter slide gate brick of this invention was tested on a large converter. After the test, the reinforced converter slide gate brick was compared with existing products in terms of pore enlargement and cracking. The average service life was 21 cycles / brick, the pore enlargement rate was an average of 40 mm / brick, and the average erosion rate was 1.91 mm / cycle. Through batch use, the results were statistically compared with existing products. The average erosion rate of the reinforced converter slide gate brick of this invention is ≤2 mm / cycle, which is lower than the erosion rate of existing alumina-carbon products ≥2.5 mm / cycle. The pore enlargement and internal condition of the slide gate were good, and no steel leakage, breakage, or cracking was observed. Therefore, the reinforced converter slide gate brick of this invention has excellent high temperature resistance, excellent thermal shock resistance, and slag corrosion resistance.

Claims

1. A slip sheet comprising, It comprises: (A) 60%-64% granular material: which comprises modified magnesia particles; (B) 36%-40% co-milling powder: which is made of 10%-18% modified magnesia fine powder, 7%-13% α-Al2O3 fine powder, 8%-10% zircon fine powder, and 5% metallic silicon powder; The total percentage of granular material and co-milling powder is 100%; It also comprises 4%-5% high-temperature binder, which is silicone-modified phenolic resin; The modified magnesia has a grain size of 5000-7000 μm and a density of 3.48-3.84 g / cm 3 ; The modified magnesia also contains magnesium aluminate spinel, which exists between the grain boundaries of the modified magnesia, and the content of the magnesium aluminate spinel is 0.01%-0.1%; The modified magnesia and zircon contain CaO.

2. The slipform according to claim 1, wherein, The preparation method of the modified magnesia is: adding additives to light-burned magnesia powder, mixing thoroughly, and then melting in an electric arc furnace, cooling after the reaction is complete to obtain modified magnesia.

3. The slipform paver of claim 2 wherein, The additives include 0.01%-2% chromium oxide and 0.2%-2% aluminum oxide.

4. The slipform according to claim 1, wherein, The high-temperature binder is a silicone-modified phenol formaldehyde resin, the molecular formula of the silicone is R 1-3 SiO 0.5-2 wherein R is a combination of one or more of methyl, phenyl, methylphenyl.

5. The slipform according to claim 4, wherein, The preparation method of the high-temperature binder includes the steps of: adding 6%-8% methylphenyl silicone resin under acidic conditions with a pH of 2-3, hydrolyzing to form a terminal hydroxyl silicone resin, and under the catalytic action of phenol and formaldehyde, the terminal hydroxyl silicone resin and phenolic resin are polycondensed to form silicone-modified phenolic resin.

6. The slipform according to claim 5, wherein, The molar ratio of phenol to formaldehyde is less than 1.

7. A method of making a slipform brick as claimed in any one of claims 1 to 6, characterised in that, It includes the steps of: batching; mixing; molding; drying; casing; drying; and after inspection, packing. It includes the steps of: batching; mixing; molding; drying; casing; drying; and after inspection, packing.

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