High thermal shock resistance rare earth composite high strength heat accumulating refractory brick for hot blast stove and preparation method thereof

Abstract

The application provides a high-thermal shock resistance rare earth composite high-strength heat storage refractory brick for hot blast stove and a preparation method thereof, and relates to the technical field of refractory bricks.The refractory brick comprises the following raw materials by weight: 15-25 parts of 5-3mm bauxite clinker aggregate, 15-25 parts of 3-1mm bauxite clinker, 10-25 parts of 1-0mm bauxite clinker, 5-17 parts of 200-mesh bauxite clinker powder, 10-20 parts of secondary aluminum ash powder, 5-10 parts of solid waste rare earth powder, 0-4 parts of soft clay, 3-11 parts of thermal expansion volume stable powder, and 3-5 parts of bonding slurry.The preparation method comprises the following steps: ingredient weighing, wet ball milling, sintering and crushing, raw material grading, ingredient mixing, mixing and stirring, pressing and forming, baking, calcination system, and finished product.The high-thermal shock resistance rare earth composite high-strength heat storage refractory brick prepared by the application has the characteristics of wide raw material distribution, low cost, low sintering temperature in the preparation process, energy saving, high compressive strength, good thermal shock resistance, high bulk density, high heat storage rate, high softening temperature and the like.

Description

Technical Field

[0001] This invention belongs to the field of refractory brick technology, specifically relating to a high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stoves and its preparation method. Background Technology

[0002] As a device for heating the blast furnace's blast air, the hot blast stove transfers heat to the checker bricks through the holes in the high-temperature flue gas after combustion. During the "blast period," the cold air is heated into hot air through convective and radiative heat exchange. The selection of refractory materials for the hot blast stove is mainly determined by the hot blast temperature. When the blast temperature is between 900 and 1100℃, high-alumina bricks, mullite bricks, or sillimanite bricks are used for the furnace lining and checker bricks in the high-temperature section; when the blast temperature is higher than 1100℃, high-alumina bricks, mullite bricks, and silica bricks are generally selected for the furnace lining or checker bricks.

[0003] Checker bricks are commonly used as heat regenerators in hot blast stoves. Current research focuses on improving the thermal performance of checker bricks, increasing heat exchange efficiency, and extending service life by reducing the size of the checker holes, thinning the equivalent thickness of the checker bricks, and increasing the heat transfer surface area per unit volume. Checker bricks, as heat regenerators, exist in the heat regenerator chamber of hot blast stoves, and their materials are mainly divided into three types: high-silicon, high-alumina, and clay. Among them, high-alumina checker bricks, with an aluminum content of approximately 70%, exhibit low creep, have an operating temperature of 800~1000℃, and are located in the middle of the heat regenerator chamber, accounting for 25~30% of the total usage.

[0004] Hot blast stoves utilize low-creep bricks containing "three stones" (alumina, siliceous iron, and silica) and high thermal shock resistant bricks. The thermal shock resistance of high-alumina refractory bricks refers to their ability to withstand rapid temperature changes without damage. Coal gangue is a solid waste generated during coal mining, washing, and processing. Andalusite is a natural, high-temperature reactive aluminosilicate refractory mineral. The phase transformation and microstructural changes of andalusite at high temperatures endow it with special properties such as excellent thermal shock resistance, high thermomechanical strength, and good erosion resistance. Adding a certain amount of andalusite during refractory castable production improves the load-bearing capacity and creep resistance of the castable. Different particle sizes of andalusite play different roles in improving material properties; coarse-grained andalusite can improve the high-temperature strength of the material, while fine-grained andalusite can improve the thermal shock resistance, effectively solving the cracking problem during the use of castables. The "three stones" minerals have good thermal shock resistance because they can irreversibly transform into mullite and SiO2 melts under high-temperature environments. Mullite has a relatively small expansion rate, α=5.3*10 -6 / ℃, which is beneficial for thermal shock resistance.

[0005] For the checker bricks in the middle and lower parts of the regenerator chamber of a hot blast stove, high-alumina, clay-based refractory materials are typically used. As the height of the regenerator chamber in large hot blast stoves increases, the pressure exerted by the upper checker bricks on the lower refractory material also increases. According to overseas investigations into the damage of checker bricks in large high-temperature hot blast stoves, it has been found that the cracking and breakage of the lower checker bricks due to periodic temperature fluctuations are constantly increasing. Therefore, in addition to continuing to control their creep characteristics, higher requirements must be placed on the room temperature compressive strength and thermal shock resistance of the products.

[0006] High-alumina refractory materials are characterized by high refractoriness, excellent impact resistance, high compressive strength, and high load softening temperature. They are used to construct high-temperature sections of various large blast furnaces, such as steelmaking furnaces, and are widely used in metallurgy, chemical industry, and construction. However, high-alumina bricks with high thermal shock resistance for hot blast stoves still face many problems in use, such as brick falling off, deformation, and breakage. These problems include high raw material costs, high firing temperatures, high production energy consumption, and the need to improve quality indicators such as strength, thermal shock resistance, and heat storage capacity.

[0007] Based on this, a high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stoves and its preparation method are proposed. Summary of the Invention

[0008] To address the shortcomings of the prior art, this invention provides a high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stoves and its preparation method, thereby solving the problems mentioned in the background art.

[0009] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0010] In a first aspect, the present invention provides a high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stoves, comprising the following raw materials in parts by weight: 65-80 parts of high-alumina bauxite clinker aggregate, 10-20 parts of secondary alumina powder, 5-10 parts of solid waste rare earth powder, 0-4 parts of soft clay, 3-11 parts of thermally expandable volume-stabilized fine powder, and 3-5 parts of binding slurry;

[0011] The binding slurry is made by mixing lignin binder and water.

[0012] As a further explanation of the present invention, the aggregate high-alumina bauxite clinker comprises the following raw materials in parts by weight: 15-25 parts of 5-3mm high-alumina bauxite clinker, 15-25 parts of 3-1mm high-alumina bauxite clinker, 10-25 parts of 1-0mm high-alumina bauxite clinker, and 5-17 parts of 200-mesh high-alumina bauxite clinker fine powder.

[0013] The present invention uses a reasonable composition of clinker with different particle sizes, which helps the particles to accumulate and the surface structure to be uniform and not rough.

[0014] As a further explanation of the present invention, the solid waste rare earth powder comprises the following raw materials in parts by weight: 40-65 parts of calcined coal gangue, 30-40 parts of rare earth tailings, and 5-20 parts of lanthanum carbonate or cerium carbonate powder.

[0015] As a further explanation of the present invention, the soft clay is specifically at least one of Su clay and Guangxi white clay; the thermally expanding volume-stabilized fine powder is specifically a mixture of andalusite powder and sillimanite powder, and the mass ratio of andalusite powder to sillimanite powder is 4:3 to 9:2.

[0016] As a further explanation of the present invention, the binding slurry is specifically made from lignin and tap water in a mass ratio of 1:2.11~2.13.

[0017] A second aspect of the present invention provides a method for preparing the above-mentioned high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stoves, comprising the following steps:

[0018] S1. Weighing of ingredients: Weigh the following raw materials in parts by weight: 40-65 parts of calcined coal gangue, 30-40 parts of rare earth tailings, and 5-20 parts of lanthanum carbonate or cerium carbonate powder.

[0019] S2. Wet ball milling: Weighed calcined coal gangue powder, rare earth tailings powder, lanthanum carbonate or cerium carbonate powder are added to a ball mill and stirred for wet ball milling. The discharged material is then dried.

[0020] S3, Sintering and Crushing: The material dried in S2 is sintered at high temperature, then crushed and sieved to obtain solid waste rare earth powder.

[0021] S4. Thoroughly and evenly mix the lignin binder and water to obtain the binder slurry;

[0022] S5. Ingredients: Weigh the raw materials according to the proportions of the high thermal shock resistant rare earth composite high-strength heat storage refractory bricks for hot blast stoves as described in any one of claims 1-5;

[0023] S6. Mixing and stirring: Mix the weighed high-alumina bauxite clinker; at the same time, add secondary aluminum ash powder, solid waste rare earth powder, soft clay, thermally expanding volume-stabilized fine powder, and binding slurry in sequence and stir thoroughly. After stirring, let stand for later use.

[0024] S7. Pressing and molding: Press the mixed raw materials after they have been left to stand into high-alumina refractory bricks to obtain a semi-finished product.

[0025] S8. Baking: Place the prepared semi-finished product into an oven for baking. After baking, remove it from the oven after it has cooled naturally.

[0026] S9. Calcination process: Alumina powder is evenly spread in an energy-saving box furnace, and then the dried semi-finished product is placed in the energy-saving box furnace for calcination.

[0027] S10. Finished product: After firing, the high-alumina refractory brick sample is naturally cooled to room temperature and taken out to obtain a high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stoves made from solid waste and rare earth tailings.

[0028] As a further explanation of the present invention, the material-to-water ratio in S2 wet ball milling is 1 / 6, and the stirring time is 15-20 minutes;

[0029] The sintering temperature in S3 is 950~1300℃, and the holding time is 1~3h. After cooling, it is put into a crusher for crushing and then passed through a 200-mesh sieve.

[0030] In S4, the lignin binder and water are mixed in a mass ratio of 1:2.11~2.13.

[0031] As a further explanation of the present invention, before the batching of S5, it is also necessary to select the raw materials: determine the different particle sizes of the aggregate high-alumina bauxite clinker, secondary aluminum ash powder, solid waste rare earth powder, soft clay, thermally expandable volume-stable fine powder, and the binder slurry raw materials.

[0032] Among them, the aggregate high-alumina bauxite clinker is selected from 5~3mm high-alumina bauxite clinker, 3~1mm high-alumina bauxite clinker, 1~0mm high-alumina bauxite clinker, and 200-mesh high-alumina bauxite clinker fine powder; the solid waste rare earth material powder is selected from 200-mesh; the secondary aluminum ash powder is selected from 200-mesh; the soft clay is selected from 200-mesh; and the thermally expanding volume-stable fine powder is selected from 200-mesh and sillimanite powder from 325-mesh.

[0033] In S5, the high-alumina bauxite clinker aggregate is prepared according to the following weight fractions: 15-25 parts of 5-3mm high-alumina bauxite clinker, 15-25 parts of 3-1mm high-alumina bauxite clinker, 10-25 parts of 1-0mm high-alumina bauxite clinker, and 5-17 parts of 200-mesh high-alumina bauxite clinker fine powder; the thermally expandable volume-stabilized fine powder is prepared according to the mass ratio of andalusite powder and sillimanite powder of 4:3-9:2.

[0034] As a further explanation of the present invention, the aggregate mixing time in S6 is 1~3 min, and the fine powder mixing time is 2~3 min. The fine powder is composed of secondary aluminum ash powder, solid waste rare earth powder, soft clay, and thermally expandable volume-stabilized fine powder. After the aggregate is mixed evenly, it is mixed together with the fine powder for 2~3 min. Finally, the prepared binding slurry is added and mixed for 4 min~6 min. After mixing, it is put into a bag and left to stand for 1 h~5 h for later use.

[0035] The molding pressure in S7 is 137MPa, and the molding rate is ≥98%.

[0036] The baking temperature in S8 is 110℃, the baking time is 24h~48h, and it needs to be baked until the moisture content is less than 2%.

[0037] As a further explanation of the present invention, the calcination conditions in S9 are specifically set as follows: heating for 0.5 h between room temperature and 80°C, and holding for 0.5 to 1 h; heating for 1 to 1.5 h between 80 and 500°C, and holding for 1 to 2 h; heating for 1 to 1.5 h between 800 and 1100°C, and holding for 1 to 2 h; heating for 1 to 1.5 h between 1100°C and the highest temperature, and holding for 5 to 6 h at the highest temperature of 1450°C to 1520°C.

[0038] This invention enhances the compressive strength of high-alumina materials while utilizing solid waste, further improving the thermal shock resistance and heat storage capacity of high-alumina refractory bricks. The functional additive, rare earth material from solid waste, has fluxing and combustion-aiding effects, not only reducing energy consumption but also contributing to the improvement of the compressive strength of high-alumina refractory bricks.

[0039] The thermal expansion volume-stabilized fine powder added in this invention, andalusite and sillimanite materials have the characteristics of small thermal expansion coefficient and improved room temperature pressure resistance. When andalusite decomposes at high temperature, it generates a certain amount of mullite and liquid phase. The produced mullite helps to improve the thermal shock stability and load softening temperature of high alumina refractory bricks. Its liquid phase promotes the sintering and densification of matrix and aggregate in the material.

[0040] The main raw materials of this invention are widely distributed, readily available, and low in cost. The solid waste rare earth material in this invention is prepared from coal gangue, rare earth tailings, and rare earth compounds. The calcination process of coal gangue, rare earth tailings, and rare earth compounds produces a physicochemical reaction: the volatile matter changes, impurities in the raw materials are removed, and at the same time, the calcination produces a chemical reaction that makes the product purer. The resulting solid waste rare earth powder is more uniform and has good performance stability. The sintering temperature of this invention is 1450℃~1520℃, which saves energy to a certain extent.

[0041] The high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stoves produced by the present invention using solid waste and rare earth tailings has excellent properties such as high density, high compressive strength, high thermal shock stability, and high heat storage.

[0042] This invention relates to a high-alumina refractory brick doped with rare earth oxides. The rare earth powder is concentrated in the pores around the fine particles, which enhances the bonding between particles inside the material. The rare earth oxides have extremely high melting points and can withstand high temperatures, allowing for use at high temperatures.

[0043] Solid waste rare earth powder can react with acidic compounds at sintering temperatures to generate substances with high refractoriness, promoting the low-temperature sintering of high-alumina refractories and improving the mechanical properties of refractory bricks to a certain extent. Doping with solid waste rare earth powder promotes the nucleation and growth of high-alumina refractories grains, improving the material's refractoriness and thermal shock stability. Doping with solid waste rare earth powder can promote the development of crystalline phases in the refractories and enhance the bonding force between particles. Doping with solid waste rare earth powder can improve the heat storage and thermal conductivity of high-alumina refractories. This invention, by simultaneously doping with sillimanite and andalusite powder, reduces the impurity content, which transforms into mullite upon heating, forming a dense network structure. Doping with solid waste rare earth powder and thermal expansion volume stabilizing powder begins to jointly promote refractory sintering around 1300℃, utilizing the volume effect to compensate for the sintering shrinkage of the refractories under high temperatures. By incorporating thermal expansion volume stabilizers and using appropriate calcination processes, the different decomposition temperatures and expansion properties of these stabilizers allow high-alumina refractory products to expand under industrial operating temperatures due to the decomposition of unconverted crystals. This generates internal stress within the refractory material, which helps resist loads and enhances its creep resistance and thermal shock resistance.

[0044] In summary, the present invention has the following advantages compared with the prior art:

[0045] This invention enhances the thermal shock resistance and compressive strength of high-alumina refractory bricks. It synthesizes a functional additive, solid waste rare earth material, from solid waste coal gangue and rare earth compounds. Simultaneously, it scientifically selects the chemical components of raw materials from different plants, rationally controls the batching, mixes and stirs the high-alumina refractory bricks, and applies a suitable firing process to prepare a high-thermal-shock-resistant rare earth composite high-strength heat-storing refractory brick for hot blast stoves. The raw materials used are widely distributed and low-cost; the firing temperature during preparation is low, saving energy; and the prepared product possesses characteristics such as high compressive strength, good thermal shock resistance, high bulk density, high heat storage rate, and high softening temperature.

[0046] The main raw materials of this invention are high-alumina granular material and high-alumina bauxite clinker as aggregates, and solid waste rare earth raw materials, thermally expanding volume-stabilized fine powder, secondary alumina powder, soft clay, and binding slurry as auxiliary materials. It is a new technology application approach for solid waste and rare earth oxides, which can obtain a high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stoves using solid waste and rare earth tailings, thereby increasing the service life of high-alumina refractory bricks for hot blast stoves.

[0047] The refractory bricks of this invention are mainly made from high-alumina bauxite clinker, secondary alumina powder, solid waste rare earth powder, and thermally expandable fine powder, etc. These raw materials are widely distributed, readily available, and low in cost. The firing temperature during preparation is low, saving energy. The resulting high-alumina refractory bricks have high density, high strength, high thermal shock resistance, and high heat storage capacity, extending the service life of high-temperature kilns and hot blast stoves and reducing maintenance costs. Compared to traditional high-alumina refractory bricks for high-temperature kilns, the material product doped with rare earth components exhibits high-temperature thermal shock resistance, high density, excellent resistance to rapid heating and cooling, high compressive strength, and high heat storage capacity. It is used in high-temperature hot blast stove linings and as checker bricks for hot blast stoves. This comprehensive utilization of solid waste broadens the application fields of rare earth products. Attached Figure Description

[0048] Figure 1 This is a flowchart of the preparation method of the present invention. Detailed Implementation

[0049] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0050] The following description, in conjunction with specific embodiments, will illustrate this point.

[0051] Table 1. Raw material information for the following examples

[0052] reagents Main ingredients 88 high alumina bauxite clinker 5~3 / 3~1 / 1~0mm <![CDATA[Weight content: Al2O3: 88%, SiO2: 2%, CaO + MgO: 1%, Fe2O3: 1.5%, R2O: 0.5%, the oxides of the remaining components account for 7%]]> 85 high alumina clinker 5~3 / 3~1 / 1~0mm <![CDATA[Weight content: Al2O3: 85%, SiO2: 5%, CaO+MgO: 1%, Fe2O3: 1.5%, R2O: 0.5%, the oxides of the remaining components account for 7%]]> 80 high alumina clinker 5~3 / 3~1 / 1~0mm <![CDATA[Weight content: Al2O3: 80%, SiO2: 10%, CaO+MgO: 1%, Fe2O3: 1.5%, R2O: 0.5%, the oxides of the remaining components account for 7%]]> Andalusite <![CDATA[Weight content: Al2O3: 58%, Fe2O3: 0.8%, K2O + Na2O: 0.5%, the remainder being oxides of the remaining components]]> sillimanite <![CDATA[Weight content: Al2O3: 57%, SiO2: 41%, Fe2O3: 0.5%, K2O + Na2O: 0.1%, the remainder being oxides of the remaining components]]> Secondary aluminum ash <![CDATA[Weight content: Al2O3: 80%, SiO2: 12%, the oxides of the remaining components account for 8%]]> Calcined coal gangue <![CDATA[Weight content: Al2O3: 30%, Fe2O3: 0.5%, SiO2: 45%, MgO + CaO: 15%, oxides of the remaining components account for 10%]]> Rare earth tailings <![CDATA[Weight content: Al2O3: 19%, SiO2: 65%, REO: 5%, the remainder is oxides of the remaining components]]> Guangxi white clay <![CDATA[Weight content: Al2O3: 33%, SiO2: 41%, CaO: 3%, Fe2O3: 3%, MgO: 4%, the oxides of the remaining components account for 16%]]>

[0053] Table 2 Device Information Table in the following embodiments

[0054] name factory model Vertical mortar mixer Shaoxing Yina Instrument Manufacturing Co., Ltd. UJZ-15 Electric programmable screw press Shandong Mingren Heavy Machinery Co., Ltd. EPK-630 Electric heating drying oven Beijing Yongguangming Medical Instrument Co., Ltd. 101-1ABS Energy-saving box-type electric furnace Tianjin Zhonghuan Experimental Electric Furnace Co., Ltd. SX-G64163 Example

[0055] like Figure 1 As shown, this embodiment provides a high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stoves, comprising the following raw materials in parts by weight: 25 parts of 5-3mm aggregate high-alumina bauxite clinker, 20 parts of 3-1mm high-alumina bauxite clinker, 10 parts of 1-0mm high-alumina bauxite clinker, 12 parts of 200-mesh high-alumina bauxite clinker fine powder, 20 parts of secondary aluminum ash powder, 10 parts of solid waste rare earth powder, 7 parts of thermally expandable volume stabilized fine powder, and 3.5 parts of lignin binding slurry; wherein, the thermally expandable volume stabilized fine powder is prepared according to a mass ratio of andalusite powder and sillimanite powder of 4:3.

[0056] The preparation method of the above-mentioned high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stove includes the following steps:

[0057] S1. Weighing of ingredients: Weigh the raw materials according to the following weight proportions: 60 parts of calcined coal gangue, 35 parts of rare earth tailings, and 5 parts of cerium carbonate powder.

[0058] S2. Wet ball milling: Add the weighed calcined coal gangue powder, rare earth tailings powder and cerium carbonate powder to the ball mill; the material-to-water ratio is 1 / 6, mix thoroughly for 15 minutes; dry the material after discharge.

[0059] S3. Sintering: The material is sintered at a high temperature of 1200℃ and held for 1 hour. After cooling, the material is crushed in a crusher and sieved through a 200-mesh sieve to obtain solid waste rare earth powder.

[0060] S4. Mix the lignin binder and tap water at a mass ratio of 1:2.11 using a high-speed separator mixer to thoroughly and evenly mix them to obtain the binder slurry.

[0061] S5. Raw material grading: The aggregate high-alumina bauxite clinker is selected from 5~3mm high-alumina bauxite clinker, 3~1mm high-alumina bauxite clinker, 1~0mm high-alumina bauxite clinker, and 200-mesh high-alumina bauxite clinker fine powder; the solid waste rare earth material powder is selected from 200-mesh; the secondary aluminum ash powder is selected from 200-mesh; the thermal expansion volume stable fine powder is selected from 200-mesh andalusite powder and 325-mesh sillimanite powder; packaged for later use.

[0062] S6. Batching: Weigh the materials according to the above-mentioned raw material composition ratio of high thermal shock resistant rare earth composite high-strength heat storage refractory bricks for hot blast stoves.

[0063] S7. Mixing and stirring: Mix the weighed aggregates of different particle sizes; at the same time, thoroughly mix the fine powder composed of secondary aluminum ash, solid waste rare earth powder, and thermally expanded volume-stabilized fine powder; the aggregate mixing time is 2 minutes, the fine powder mixing time is 3 minutes, after the aggregate is mixed evenly, add the fine powder and mix together for 2 minutes, and finally add the prepared binding slurry and mix for 5 minutes; after mixing, put it into a bag and let it stand for 1 hour before use.

[0064] S8. Pressing and molding: The mixture after standing is pressed into high-alumina refractory bricks using an electric programmable screw press. The size of the high-alumina bricks is pressed according to the user's requirements, such as standard bricks and others; the molding pressure is 137MPa, and the molding rate is ≥98%; a semi-finished product is obtained.

[0065] S9. Baking: Place the pressed semi-finished product into an oven and bake at 110℃ for 24 hours. After baking, let it cool naturally in the oven and then take it out. The moisture content after baking is <2%.

[0066] S10. Calcination process: Alumina powder is evenly spread in an energy-saving box furnace, and then the dried semi-finished product is placed in the energy-saving box furnace for calcination. The calcination conditions are set as follows: heating for 0.5 hours and holding for 0.5 hours between room temperature and 80°C; heating for 1.5 hours and holding for 2 hours between 80°C and 500°C; heating for 1.5 hours and holding for 2 hours between 800°C and 1100°C; heating for 1 hour between 1100°C and 1450°C and holding at a high temperature of 1450°C for 6 hours.

[0067] S11. Finished product: After the high-alumina brick sample is fired, it is naturally cooled to room temperature as the furnace temperature is reduced, and then it is taken out to obtain the finished product of high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stove made from solid waste and rare earth tailings.

[0068] The following are the test results for the high thermal shock resistant rare earth composite high-strength heat storage refractory bricks for hot blast stoves prepared using solid waste and rare earth tailings:

[0069] The bulk density is 2.58 g / cm³. 3 It has an apparent porosity of 23.22%, a water absorption rate of 8.5%, a compressive strength of 72.09 MPa, a heat storage rate of 13.60%, and thermal shock resistance: thermal shock stability ≥115 cycles of water cooling at 1100℃. Example

[0070] This embodiment provides a high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stoves, comprising the following raw materials in parts by weight: 25 parts of 5-3mm aggregate high-alumina bauxite clinker, 15 parts of 3-1mm high-alumina bauxite clinker, 25 parts of 1-0mm high-alumina bauxite clinker, 5 parts of 200-mesh high-alumina bauxite clinker fine powder, 10 parts of secondary alumina ash powder, 6 parts of solid waste rare earth powder, 1 part of soft clay, 11 parts of thermally expandable volume stabilized fine powder, and 4.5 parts of lignin binding slurry; wherein, the thermally expandable volume stabilized fine powder is prepared according to a mass ratio of andalusite powder and sillimanite powder of 2:1.

[0071] The preparation method of the above-mentioned high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stove includes the following steps:

[0072] S1. Weighing of ingredients: Weigh the raw materials according to the following weight proportions: 65 parts of calcined coal gangue, 30 parts of rare earth tailings, and 10 parts of lanthanum carbonate powder.

[0073] S2. Wet ball milling: Add the weighed calcined coal gangue powder, rare earth tailings powder and lanthanum carbonate powder to the ball mill; the material-to-water ratio is 1 / 6, mix thoroughly for 20 minutes; dry after discharge.

[0074] S3. Sintering: The material is sintered at a high temperature of 950℃ and held for 2 hours. After cooling, the material is crushed in a crusher and sieved through a 200-mesh sieve to obtain solid waste rare earth powder.

[0075] S4. Mix the lignin binder and tap water at a mass ratio of 1:2.12 using a high-speed separator mixer to thoroughly and evenly mix them to obtain the binder slurry.

[0076] S5. Raw material grading: The aggregate high-alumina bauxite clinker is selected from 5~3mm high-alumina bauxite clinker, 3~1mm high-alumina bauxite clinker, 1~0mm high-alumina bauxite clinker, and 200-mesh high-alumina bauxite clinker fine powder; the solid waste rare earth powder is selected from 200-mesh; the secondary aluminum ash powder is selected from 200-mesh; the soft clay is selected from 200-mesh; and the thermally expanding volume-stable fine powder is selected from 200-mesh and sillimanite powder from 325-mesh; packaged for later use.

[0077] S6. Batching: Weigh the materials according to the above-mentioned raw material composition ratio of high thermal shock resistant rare earth composite high-strength heat storage refractory bricks for hot blast stoves.

[0078] S7. Mixing and stirring: Mix the weighed aggregates of different particle sizes; at the same time, thoroughly mix the fine powder composed of secondary aluminum ash, solid waste rare earth powder, soft clay, and thermally expandable volume-stabilized fine powder; the aggregate mixing time is 1 minute, the fine powder mixing time is 2 minutes, after the aggregate is mixed evenly, add the fine powder and mix together for 2 minutes, and finally add the prepared binding slurry and mix for 4 minutes; after mixing, put it into a bag and let it stand for 2 hours before use.

[0079] S8. Pressing and molding: The mixture after standing is pressed into high-alumina refractory bricks using an electric programmable screw press. The size of the high-alumina bricks is pressed according to the user's requirements, such as standard bricks and others; the molding pressure is 137MPa, and the molding rate is ≥98%; a semi-finished product is obtained.

[0080] S9. Baking: Place the pressed semi-finished product into an oven and bake at 110℃ for 48 hours. After baking, allow it to cool naturally in the oven before removing it. The moisture content after baking should be less than 1%.

[0081] S10 Calcination process: Alumina powder is evenly spread in an energy-saving box furnace, and then the dried semi-finished product is placed in the energy-saving box furnace for calcination. The calcination conditions are set as follows: heating for 0.5 hours and holding for 0.5 hours between room temperature and 80°C; heating for 1 hour and holding for 2 hours between 80°C and 500°C; heating for 1 hour and holding for 2 hours between 800°C and 1100°C; heating for 1 hour between 1100°C and 1450°C and holding for 5 hours at a high temperature of 1460°C.

[0082] S11. Finished product: After firing, the high-alumina brick sample is naturally cooled to room temperature and taken out to obtain the finished product of high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stove made from solid waste and rare earth tailings.

[0083] The above-mentioned high thermal shock resistant rare earth composite high-strength heat storage refractory brick products for hot blast stoves using solid waste and rare earth tailings are tested as follows:

[0084] The bulk density is 2.90 g / cm³. 3 It has an apparent porosity of 18.69%, a water absorption rate of 6.45%, a compressive strength of 76.58 MPa, a heat storage rate of 10.11%, and thermal shock resistance: thermal shock stability ≥120 times of water cooling at 1100℃. Example

[0085] This embodiment provides a high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stoves, comprising the following raw materials in parts by weight: 20 parts of 5-3mm aggregate high-alumina bauxite clinker, 25 parts of 3-1mm high-alumina bauxite clinker, 15 parts of 1-0mm high-alumina bauxite clinker, 17 parts of 200-mesh high-alumina bauxite clinker fine powder, 15 parts of secondary aluminum ash powder, 5 parts of solid waste rare earth powder, 2 parts of soft clay, 10 parts of thermally expandable volume stabilized fine powder, and 3 parts of lignin binding slurry; wherein, the thermally expandable volume stabilized fine powder is prepared according to a mass ratio of andalusite powder and sillimanite powder of 7:3.

[0086] The preparation method of the above-mentioned high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stove includes the following steps:

[0087] S1. Weighing of ingredients: Weigh the raw materials according to the following weight proportions: 60 parts of calcined coal gangue, 35 parts of rare earth tailings, and 10 parts of cerium carbonate powder.

[0088] S2. Wet ball milling: Add the weighed calcined coal gangue powder, rare earth tailings powder and cerium carbonate powder to the ball mill; the material-to-water ratio is 1 / 6, mix thoroughly for 20 minutes; dry after discharge.

[0089] S3. Sintering: The material is sintered at a high temperature of 1100℃ and held for 2 hours. After cooling, the material is crushed in a crusher and sieved through a 200-mesh sieve to obtain solid waste rare earth powder.

[0090] S4. Mix the lignin binder and tap water at a mass ratio of 1:2.13 using a high-speed separator mixer to thoroughly and evenly mix them to obtain the binder slurry.

[0091] S5. Raw material grading: The aggregate high-alumina bauxite clinker is selected from 5~3mm high-alumina bauxite clinker, 3~1mm high-alumina bauxite clinker, 1~0mm high-alumina bauxite clinker, and 200-mesh high-alumina bauxite clinker fine powder; the solid waste rare earth powder is selected from 200-mesh; the secondary aluminum ash powder is selected from 200-mesh; the soft clay is selected from 200-mesh; and the thermally expanding volume-stable fine powder is selected from 200-mesh and sillimanite powder from 325-mesh; packaged for later use.

[0092] S6. Batching: Weigh the materials according to the above-mentioned raw material composition ratio of high thermal shock resistant rare earth composite high-strength heat storage refractory bricks for hot blast stoves.

[0093] S7. Mixing and stirring: Mix the weighed aggregates of different particle sizes; at the same time, thoroughly mix the fine powder composed of secondary aluminum ash, solid waste rare earth powder, soft clay, and thermally expandable volume-stabilized fine powder; the aggregate mixing time is 3 minutes, the fine powder mixing time is 2 minutes, after the aggregate is mixed evenly, add the fine powder and mix together for 3 minutes, and finally add the prepared binding slurry and mix for 6 minutes; after mixing, put it into bags and let it stand for 5 hours before use.

[0094] S8. Pressing and molding: The uniformly mixed materials are pressed into high-alumina refractory bricks using an electric programmable screw press. The size of the high-alumina bricks is pressed according to the user's requirements, such as standard bricks and others; the molding pressure is 137MPa, and the molding rate is ≥98%; a semi-finished product is obtained.

[0095] S9. Baking: Place the pressed semi-finished product into an oven and bake at 110℃ for 48 hours. After baking, remove the product after it cools naturally in the oven. The moisture content after baking should be less than 2%.

[0096] S10 Calcination process: Alumina powder is evenly spread in an energy-saving box furnace, and then the dried semi-finished product is placed in the energy-saving box furnace for calcination. The calcination conditions are set as follows: heating at room temperature to 80℃ for 0.5h and holding for 1h; heating at 80℃ to 500℃ for 1.5h and holding for 1h; heating at 800℃ to 1100℃ for 1.5h and holding for 1h; heating at 1100℃ to 1520℃ for 1.5h and holding at a high temperature of 1520℃ for 5h.

[0097] S11. Finished product: After the high-alumina brick sample is fired, it is naturally cooled to room temperature as the furnace temperature is reduced, and then it is taken out to obtain the finished product of a high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stoves made from solid waste and rare earth tailings.

[0098] The above-mentioned high thermal shock resistant rare earth composite high-strength heat storage refractory brick products for hot blast stoves using solid waste and rare earth tailings are tested as follows:

[0099] The bulk density is 2.920 g / cm³. 3 It has an apparent porosity of 18.50%, a water absorption rate of 6.34%, a compressive strength of 80.63 MPa, a heat storage rate of 11.12%, and thermal shock resistance: thermal shock stability ≥125 times of water cooling at 1100℃. Example

[0100] This embodiment provides a high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stoves, comprising the following raw materials in parts by weight: 15 parts of 5-3mm aggregate high-alumina bauxite clinker, 25 parts of 3-1mm high-alumina bauxite clinker, 20 parts of 1-0mm high-alumina bauxite clinker, 15 parts of 200-mesh high-alumina bauxite clinker fine powder, 17 parts of secondary alumina ash powder, 7 parts of solid waste rare earth powder, 4 parts of soft clay, 3 parts of thermally expandable volume stabilized fine powder, and 5 parts of lignin binding slurry; wherein, the thermally expandable volume stabilized fine powder is prepared according to a mass ratio of andalusite powder and sillimanite powder of 9:2.

[0101] The preparation method of the above-mentioned high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stove includes the following steps:

[0102] S1. Weighing of ingredients: Weigh the raw materials according to the following weight parts: 40 parts of calcined coal gangue, 40 parts of rare earth tailings, and 20 parts of cerium carbonate powder.

[0103] S2. Wet ball milling: Add the weighed calcined coal gangue powder, rare earth tailings powder and cerium carbonate powder to the ball mill; the material-to-water ratio is 1 / 6, mix thoroughly for 15 minutes; dry the material after discharge.

[0104] S3. Sintering: The material is sintered at a high temperature of 1300℃ and held for 3 hours. After cooling, the material is crushed in a crusher and sieved through a 200-mesh screen to obtain solid waste rare earth powder.

[0105] S4. Mix the lignin binder and tap water at a mass ratio of 1:2.13 using a high-speed separator mixer to thoroughly and evenly mix them to obtain the binder slurry.

[0106] S5. Raw material grading: The aggregate high-alumina bauxite clinker is selected from 5~3mm high-alumina bauxite clinker, 3~1mm high-alumina bauxite clinker, 1~0mm high-alumina bauxite clinker, and 200-mesh high-alumina bauxite clinker fine powder; the solid waste rare earth powder is selected from 200-mesh; the secondary aluminum ash powder is selected from 200-mesh; the soft clay is selected from 200-mesh; and the thermally expanding volume-stable fine powder is selected from 200-mesh and sillimanite powder from 325-mesh; packaged for later use.

[0107] S6. Batching: Weigh the materials according to the above-mentioned raw material composition ratio of high thermal shock resistant rare earth composite high-strength heat storage refractory bricks for hot blast stoves.

[0108] S7. Mixing and stirring: Mix the weighed aggregates of different particle sizes; at the same time, thoroughly mix the fine powder composed of secondary aluminum ash, solid waste rare earth powder, soft clay, and thermally expandable volume-stabilized fine powder; the aggregate mixing time is 2 minutes, the fine powder mixing time is 2 minutes, after the aggregate is mixed evenly, add the fine powder and mix together for 3 minutes, and finally add the prepared binder and mix for 5 minutes; after mixing, put it into a bag and let it stand for 3 hours before use.

[0109] S8. Pressing and molding: The mixture after standing is pressed into high-alumina refractory bricks using an electric programmable screw press. The size of the high-alumina bricks is pressed according to the user's requirements, such as standard bricks and others; the molding pressure is 137MPa, and the molding rate is ≥98%; a semi-finished product is obtained.

[0110] S9. Baking: Place the pressed semi-finished product into an oven and bake at 110℃ for 24 hours. After baking, let it cool naturally in the oven and then take it out. The moisture content after baking is <2%.

[0111] S10. Calcination process: Alumina powder is evenly spread in an energy-saving box-type electric furnace, and then the dried semi-finished product is placed in the energy-saving box-type electric furnace for calcination. The calcination conditions are set as follows: heating for 0.5 hours and holding for 0.5 hours between room temperature and 80°C; heating for 1.5 hours and holding for 2 hours between 80°C and 500°C; heating for 1.5 hours and holding for 2 hours between 800°C and 1100°C; heating for 1.5 hours between 1100°C and 1480°C and holding for 5 hours at a high temperature of 1480°C.

[0112] S11. Finished product: After firing, the high-alumina brick sample is naturally cooled to room temperature and taken out to obtain the finished product of high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stove made from solid waste and rare earth tailings.

[0113] The above-mentioned high thermal shock resistant rare earth composite high-strength heat storage refractory brick products for hot blast stoves using solid waste and rare earth tailings are tested as follows:

[0114] The bulk density is 2.66 g / cm³. 3 It has an apparent porosity of 24.44%, a water absorption rate of 9.33%, a compressive strength of 65MPa, a heat storage rate of 12.55%, and thermal shock resistance: thermal shock stability ≥102 cycles of water cooling at 1100℃.

[0115] Comparative Example 1

[0116] This comparative example provides a refractory brick for a hot blast stove, comprising the following raw materials in parts by weight: 25 parts of 5-3mm high-alumina bauxite clinker, 20 parts of 3-1mm high-alumina bauxite clinker, 10 parts of 1-0mm high-alumina bauxite clinker, 16 parts of 200-mesh high-alumina bauxite clinker fine powder, 23 parts of secondary alumina ash powder, 10 parts of solid waste rare earth powder, 0 parts of thermally expandable volume-stabilized fine powder, and 3.5 parts of lignin-based binder slurry.

[0117] The preparation method of the above-mentioned high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stove includes the following steps:

[0118] S1. Weighing of ingredients: Weigh the raw materials according to the following weight proportions: 60 parts of calcined coal gangue, 35 parts of rare earth tailings, and 5 parts of cerium carbonate powder.

[0119] S2. Wet ball milling: Add the weighed calcined coal gangue powder, rare earth tailings powder and cerium carbonate powder to the ball mill; the material-to-water ratio is 1 / 6, mix thoroughly for 15 minutes; dry the material after discharge.

[0120] S3. Sintering: The material is sintered at a high temperature of 1200℃ and held for 1 hour. After cooling, the material is crushed in a crusher and sieved through a 200-mesh sieve to obtain solid waste rare earth powder.

[0121] S4. Mix the lignin binder and tap water at a mass ratio of 1:2.11 using a high-speed separator mixer to thoroughly and evenly mix them to obtain the binder slurry.

[0122] S5. Raw material grading: The aggregate high-alumina bauxite clinker is selected from 5~3mm high-alumina bauxite clinker, 3~1mm high-alumina bauxite clinker, 1~0mm high-alumina bauxite clinker, and 200-mesh high-alumina bauxite clinker fine powder; the solid waste rare earth material powder is selected from 200-mesh; the secondary aluminum ash powder is selected from 200-mesh; packaged for later use.

[0123] S6. Batching: Weigh the materials according to the above-mentioned raw material composition ratio of high thermal shock resistant rare earth composite high-strength heat storage refractory bricks for hot blast stoves.

[0124] S7. Mixing and stirring: Mix the weighed aggregates of different particle sizes; at the same time, thoroughly mix the fine powder composed of secondary aluminum ash and solid waste rare earth powder; the aggregate mixing time is 2 minutes, the fine powder mixing time is 3 minutes, after the aggregate is mixed evenly, add the fine powder and mix together for 2 minutes, and finally add the prepared binding slurry and mix for 5 minutes; after mixing, put it into a bag and let it stand for 1 hour before use.

[0125] S8. Pressing and molding: The mixture after standing is pressed into high-alumina refractory bricks using an electric programmable screw press. The size of the high-alumina bricks is pressed according to the user's requirements, such as standard bricks and others; the molding pressure is 137MPa, and the molding rate is ≥98%; a semi-finished product is obtained.

[0126] S9. Baking: Place the pressed semi-finished product into an oven and bake at 110℃ for 24 hours. After baking, let it cool naturally in the oven and then take it out. The moisture content after baking is <2%.

[0127] S10. Calcination process: Alumina powder is evenly spread in an energy-saving box furnace, and then the dried semi-finished product is placed in the energy-saving box furnace for calcination. The calcination conditions are set as follows: heating for 0.5 hours and holding for 0.5 hours between room temperature and 80°C; heating for 1.5 hours and holding for 2 hours between 80°C and 500°C; heating for 1.5 hours and holding for 2 hours between 800°C and 1100°C; heating for 1 hour between 1100°C and 1450°C and holding at a high temperature of 1450°C for 6 hours.

[0128] S11. Finished product: After firing, the high-alumina brick sample is naturally cooled to room temperature by the furnace temperature, and then the refractory brick finished product is obtained.

[0129] The above-mentioned refractory bricks for hot blast stoves were tested as follows:

[0130] The bulk density is 2.59 g / cm³. 3 It has an apparent porosity of 23.01%, a water absorption rate of 8.7%, a compressive strength of 73.96 MPa, a heat storage rate of 13.82%, and thermal shock resistance: thermal shock stability at 1100℃ and water cooling for 76 cycles.

[0131] The performance test results above show that Comparative Example 1 did not contain thermally expanding volume-stabilizing fine powder, resulting in poor high-temperature performance and thermal shock stability, and a low number of water cooling cycles at 1100℃.

[0132] Comparative Example 2

[0133] This embodiment provides a refractory brick for a hot blast stove, comprising the following raw materials in parts by weight: 25 parts of 5-3mm high-alumina bauxite clinker, 20 parts of 3-1mm high-alumina bauxite clinker, 10 parts of 1-0mm high-alumina bauxite clinker, 12 parts of 200-mesh high-alumina bauxite clinker fine powder, 24 parts of secondary alumina ash powder, 0 parts of solid waste rare earth powder, 7 parts of thermally expandable volume stabilized fine powder, 6 parts of soft clay, and 3.5 parts of lignin binding slurry; wherein the thermally expandable volume stabilized fine powder is prepared according to a mass ratio of andalusite powder and sillimanite powder of 4:3.

[0134] The above-mentioned method for preparing refractory bricks for hot blast stoves includes the following steps:

[0135] S1. Mix the lignin binder and tap water at a mass ratio of 1:2.11 using a high-speed separator mixer to thoroughly and evenly mix them to obtain the binder slurry.

[0136] S2. Raw material grading: The aggregate high-alumina bauxite clinker is selected from 5~3mm high-alumina bauxite clinker, 3~1mm high-alumina bauxite clinker, 1~0mm high-alumina bauxite clinker, and 200-mesh high-alumina bauxite clinker fine powder; the secondary aluminum ash powder is selected from 200-mesh; the soft clay is selected from 200-mesh; the thermally expanding volume-stable fine powder is selected from 200-mesh andalusite powder and 325-mesh sillimanite powder; packaged for later use.

[0137] S3. Batching: Weigh the materials according to the above-mentioned raw material composition ratio of refractory bricks for hot blast stoves.

[0138] S4. Mixing and stirring: Mix the weighed aggregates of different particle sizes; at the same time, thoroughly mix the fine powder composed of secondary aluminum ash, thermally expanded volume-stabilized fine powder and soft clay; the aggregate mixing time is 2 minutes, the fine powder mixing time is 3 minutes, after the aggregate is mixed evenly, add the fine powder and mix together for 2 minutes, and finally add the prepared binding slurry and mix for 5 minutes; after mixing, put it into a bag and let it stand for 1 hour before use.

[0139] S4. Pressing and molding: The mixture after standing is pressed into high-alumina refractory bricks using an electric programmable screw press. The size of the high-alumina bricks is pressed according to the user's requirements, such as standard bricks and others; the molding pressure is 137MPa, and the molding rate is ≥98%; a semi-finished product is obtained.

[0140] S5. Baking: Place the pressed semi-finished product into an oven and bake at 110℃ for 24 hours. After baking, let it cool naturally in the oven and then take it out. The moisture content after baking is <2%.

[0141] S5. Calcination process: Alumina powder is evenly spread in an energy-saving box furnace, and then the dried semi-finished product is placed in the energy-saving box furnace for calcination. The calcination conditions are set as follows: heating for 0.5 hours and holding for 0.5 hours between room temperature and 80°C; heating for 1.5 hours and holding for 2 hours between 80°C and 500°C; heating for 1.5 hours and holding for 2 hours between 800°C and 1100°C; heating for 1 hour between 1100°C and 1450°C and holding at a high temperature of 1450°C for 6 hours.

[0142] S11. Finished product: After firing, the high-alumina brick sample is naturally cooled to room temperature by the furnace temperature, and then the refractory brick finished product is obtained.

[0143] The above-mentioned refractory brick products were tested as follows:

[0144] The bulk density is 2.52 g / cm³. 3 It has an apparent porosity of 24.35%, a water absorption rate of 8.62%, a compressive strength of 56.83 MPa, and thermal shock resistance: thermal shock stability ≥118 cycles of water cooling at 1100℃.

[0145] The performance test results above show that Comparative Example 2 did not contain any solid waste rare earth powder, so its compressive strength was worse than that of Example 1, and its bulk density was also lower.

[0146] Comparative Example 3

[0147] This embodiment provides a refractory brick for a hot blast stove, comprising the following raw materials in parts by weight: 25 parts of 5-3mm aggregate high-alumina bauxite clinker, 20 parts of 3-1mm high-alumina bauxite clinker, 10 parts of 1-0mm high-alumina bauxite clinker, 19 parts of 200-mesh high-alumina bauxite clinker fine powder, 20 parts of secondary aluminum ash powder, 0 parts of solid waste rare earth powder, 0 parts of thermally expanded volume stabilized fine powder, 6 parts of calcined coal gangue, and 3.5 parts of lignin binding slurry.

[0148] The above-mentioned method for preparing refractory bricks for hot blast stoves includes the following steps:

[0149] S1. Mix the lignin binder and tap water at a mass ratio of 1:2.11 using a high-speed separator mixer to thoroughly and evenly mix them to obtain the binder slurry.

[0150] S2. Raw material grading: The aggregate high-alumina bauxite clinker is selected from 5~3mm high-alumina bauxite clinker, 3~1mm high-alumina bauxite clinker, 1~0mm high-alumina bauxite clinker, and 200-mesh high-alumina bauxite clinker fine powder; the secondary aluminum ash powder is selected from 200-mesh; the calcined coal gangue is selected from 200-mesh; and it is packaged for later use.

[0151] S3. Batching: Weigh the materials according to the above-mentioned raw material composition ratio of refractory bricks for hot blast stoves.

[0152] S4. Mixing and stirring: Mix the weighed aggregates of different particle sizes together; at the same time, thoroughly mix the fine powder of high-alumina bauxite clinker, secondary alumina ash, and fine powder of calcined coal gangue; the aggregate mixing time is 2 minutes, the fine powder mixing time is 3 minutes, after the aggregate is mixed evenly, add the fine powder and mix together for 2 minutes, and finally add the prepared binding slurry and mix for 5 minutes; after mixing, put it into bags and let it stand for 1 hour before use.

[0153] S4. Pressing and molding: The mixture after standing is pressed into high-alumina refractory bricks using an electric programmable screw press. The size of the high-alumina bricks is pressed according to the user's requirements, such as standard bricks and others; the molding pressure is 137MPa, and the molding rate is ≥98%; a semi-finished product is obtained.

[0154] S5. Baking: Place the pressed semi-finished product into an oven and bake at 110℃ for 24 hours. After baking, let it cool naturally in the oven and then take it out. The moisture content after baking is <2%.

[0155] S5. Calcination process: Alumina powder is evenly spread in an energy-saving box furnace, and then the dried semi-finished product is placed in the energy-saving box furnace for calcination. The calcination conditions are set as follows: heating for 0.5 hours and holding for 0.5 hours between room temperature and 80°C; heating for 1.5 hours and holding for 2 hours between 80°C and 500°C; heating for 1.5 hours and holding for 2 hours between 800°C and 1100°C; heating for 1 hour between 1100°C and 1450°C and holding at a high temperature of 1450°C for 6 hours.

[0156] S11. Finished product: After firing, the high-alumina brick sample is naturally cooled to room temperature by the furnace temperature, and then the refractory brick finished product is obtained.

[0157] The above-mentioned refractory brick products were tested as follows:

[0158] The bulk density is 2.51 g / cm³. 3 It has an apparent porosity of 24.96%, a water absorption rate of 9.2%, a compressive strength of 52.37 MPa, and thermal shock resistance: thermal shock stability ≥69 cycles of water cooling at 1100℃.

[0159] The performance test results above show that Comparative Example 3 did not add thermally expanding volume-stabilized fine powder, and replaced solid waste rare earth powder with single calcined coal gangue fine powder. Therefore, compared with Example 1, the product has poor thermal shock resistance and compressive strength, and low bulk density.

[0160] Comparative Example 4

[0161] This embodiment provides a refractory brick for a hot blast stove, comprising the following raw materials in parts by weight: 25 parts of 5-3mm aggregate high-alumina bauxite clinker, 20 parts of 3-1mm high-alumina bauxite clinker, 10 parts of 1-0mm high-alumina bauxite clinker, 19 parts of 200-mesh high-alumina bauxite clinker fine powder, 20 parts of secondary aluminum ash powder, 0 parts of solid waste rare earth powder, 0 parts of thermally expanded volume stabilized fine powder, 6 parts of soft clay, 5 parts of rare earth compound lanthanum carbonate powder, and 3.5 parts of lignin binding slurry.

[0162] The above-mentioned method for preparing refractory bricks for hot blast stoves includes the following steps:

[0163] S1. Mix the lignin binder and tap water at a mass ratio of 1:2.11 using a high-speed separator mixer to thoroughly and evenly mix them to obtain the binder slurry.

[0164] S2. Raw material grading: The aggregate high-alumina bauxite clinker is selected from 5~3mm high-alumina bauxite clinker, 3~1mm high-alumina bauxite clinker, 1~0mm high-alumina bauxite clinker, and 200-mesh high-alumina bauxite clinker fine powder; secondary aluminum ash powder is selected from 200-mesh; soft clay is selected from 200-mesh; rare earth compound lanthanum carbonate powder is selected from 200-mesh; packaged for later use.

[0165] S3. Batching: Weigh the materials according to the above-mentioned raw material composition ratio of refractory bricks for hot blast stoves.

[0166] S4. Mixing and stirring: Mix the weighed aggregates of different particle sizes together; at the same time, thoroughly mix the high-alumina bauxite clinker fine powder, secondary alumina ash, soft clay fine powder, and rare earth compound lanthanum carbonate powder; the aggregate mixing time is 2 minutes, the fine powder mixing time is 3 minutes, after the aggregate is mixed evenly, add the fine powder and mix together for 2 minutes, and finally add the prepared binding slurry and mix for 5 minutes; after mixing, put it into bags and let it stand for 1 hour before use.

[0167] S4. Pressing and molding: The mixture after standing is pressed into high-alumina refractory bricks using an electric programmable screw press. The size of the high-alumina bricks is pressed according to the user's requirements, such as standard bricks and others; the molding pressure is 137MPa, and the molding rate is ≥98%; a semi-finished product is obtained.

[0168] S5. Baking: Place the pressed semi-finished product into an oven and bake at 110℃ for 24 hours. After baking, let it cool naturally in the oven and then take it out. The moisture content after baking is <2%.

[0169] S5. Calcination process: Alumina powder is evenly spread in an energy-saving box furnace, and then the dried semi-finished product is placed in the energy-saving box furnace for calcination. The calcination conditions are set as follows: heating for 0.5 hours and holding for 0.5 hours between room temperature and 80°C; heating for 1.5 hours and holding for 2 hours between 80°C and 500°C; heating for 1.5 hours and holding for 2 hours between 800°C and 1100°C; heating for 1 hour between 1100°C and 1450°C and holding at a high temperature of 1450°C for 6 hours.

[0170] S11. Finished product: After firing, the high-alumina brick sample is naturally cooled to room temperature by the furnace temperature, and then the refractory brick finished product is obtained.

[0171] The above-mentioned refractory brick products were tested as follows:

[0172] The bulk density is 2.57 g / cm³. 3 It has an apparent porosity of 23.47%, a water absorption rate of 8.67%, a compressive strength of 61.9 MPa, and thermal shock resistance: thermal shock stability ≥71 cycles of water cooling at 1100℃.

[0173] The performance test results above show that Comparative Example 4 did not add thermally expanding volume-stabilizing fine powder, and replaced solid waste rare earth powder with a single rare earth compound, lanthanum carbonate powder. Therefore, compared with Example 1, the product has poorer thermal shock resistance and pressure resistance.

[0174] In summary, the main raw material aggregate, high-alumina bauxite clinker, used in Examples 1-4 of this invention is widely distributed and readily available. High-alumina bauxite clinker is prepared by high-temperature calcination of bauxite ore. my country's reserves of high-alumina bauxite are approximately over one billion tons, primarily produced in Shanxi, Henan, and Guizhou provinces. Secondary aluminum ash and calcined coal gangue, as solid wastes, are produced by numerous enterprises. Rare earth tailings are mainly produced in Baotou, Inner Mongolia; Ganzhou, Jiangxi; and Mianning, Sichuan. my country's andalusite resources are mainly distributed in Henan, Xinjiang, Shaanxi, Jilin, and other regions. All raw materials used are widely distributed and readily available.

[0175] The formulation of this invention contains solid waste rare earth powder, which enhances the interparticle bonding within the material; increases the density of high-alumina refractory materials; and improves mechanical properties. The solid waste rare earth powder promotes the nucleation and growth of high-alumina refractory grains, improving the material's refractoriness and thermal shock resistance. The formulation also incorporates sillimanite and andalusite powder. Under appropriate calcination processes, their different decomposition temperatures and expansion properties allow the high-alumina refractory products to expand due to the decomposition of unconverted crystals at industrial operating temperatures. This generates internal stress within the refractory material, resisting loads and enhancing creep and thermal shock resistance.

[0176] This invention provides a high-thermal-shock-resistant rare-earth composite high-strength heat-storage refractory brick for hot blast stoves, prepared using solid waste and rare-earth compounds. This brick exhibits high pressure resistance, excellent thermal shock resistance, and improved heat storage capacity, extending the service life of hot blast stoves in high-temperature kilns and reducing maintenance costs. The formula of this invention utilizes secondary aluminum ash from solid waste, calcined coal gangue, and rare-earth tailings, saving production costs, fully utilizing resources, and turning waste into treasure, resulting in significant economic and social benefits.

[0177] This invention provides a method for preparing high thermal shock resistant rare earth composite high-strength heat-storing refractory bricks for hot blast stoves using solid waste and rare earth tailings. Solid waste rare earth powder is prepared through wet ball milling and sintering. A unique slurry formulation is used, and after uniform mixing with a high-speed separator and a hydrometer to ensure it meets requirements, the slurry is added. The mixing process is strictly controlled in terms of sequence and duration: aggregates are mixed separately in the mixer for 1-2 minutes, fine powders for 2-3 minutes, and then the aggregates are mixed with the fine powders for 2-3 minutes. Finally, the prepared binder is added and mixed for 4-6 minutes. After mixing, the mixture is placed in bags, sealed, and left to stand for 1-5 hours.

[0178] The pressing process utilizes an EPK-630 electric programmable screw press with a pressing force of 137 MPa. The calcination process employs a unique multi-gradient heating and holding regime to promote sintering of the material at different temperature zones: heating for 0.5 hours between room temperature and 80°C, followed by holding for 0.5-1 hours; heating for 1-1.5 hours between 80-500°C, followed by holding for 1-2 hours; heating for 1-1.5 hours between 800-1100°C, followed by holding for 1-2 hours; heating for 1-1.5 hours between 1100°C and the highest temperature, followed by holding for 5-6 hours at the highest temperature of 1450°C-1520°C. The product of this invention undergoes relevant performance testing according to national standards after production.

[0179] The present invention provides a high-thermal-shock-resistant rare-earth composite high-strength regenerative refractory brick for blast furnace hot blast stoves. The firing temperature range is 1450–1520℃. The firing temperature for this high-strength, high-alumina brick is low, resulting in low energy consumption. Rare-earth lanthanum and cerium oxides have certain fluxing and firing aid effects, reducing energy consumption while improving the compressive strength of the high-alumina bricks. Andalusite and sillimanite materials have low coefficients of thermal expansion, improve room-temperature compressive strength, and promote sintering densification, all of which contribute to enhancing the thermal shock resistance of the high-alumina bricks.

[0180] The high thermal shock resistant rare earth composite high-strength heat-storing refractory brick for blast furnace hot blast stoves provided by this invention has a bulk density range of 2.58~2.92 g / cm³. 3 The compressive strength ranges from 65 to 80.63 MPa, the water absorption ranges from 6.34% to 10.71%, the heat storage rate is increased from 10.11% to 13.60%, and the thermal shock resistance is >102 to 125 times after water cooling at 1100℃. The product has high bulk density, high compressive strength, high thermal shock resistance, and high heat storage.

[0181] High-alumina refractory bricks for hot blast stoves maintain high strength while extending their service life under rapid cooling and heating conditions, exhibiting high heat storage capacity. Furthermore, the comprehensive utilization of solid waste broadens the application areas of rare earth products, providing a new market avenue for high-alumina refractory bricks used in hot blast stoves.

[0182] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0183] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A rare earth composite high-strength heat-storing refractory brick with high thermal shock resistance for hot blast stoves, characterized in that, The raw materials include the following parts by weight: 65-80 parts of high-alumina bauxite clinker, 10-20 parts of secondary alumina powder, 5-10 parts of solid waste rare earth powder, 0-4 parts of soft clay, 3-11 parts of thermally expandable volume-stabilized fine powder, and 3-5 parts of binding slurry. The binding slurry is made by mixing lignin binder and water; The solid waste rare earth powder comprises the following raw materials in parts by weight: 40-65 parts of calcined coal gangue, 30-40 parts of rare earth tailings, and 5-20 parts of lanthanum carbonate or cerium carbonate powder. The preparation process of the solid waste rare earth powder is as follows: S1. Weighing of ingredients: Weigh the following raw materials in parts by weight: 40-65 parts of calcined coal gangue, 30-40 parts of rare earth tailings, and 5-20 parts of lanthanum carbonate or cerium carbonate powder. S2. Wet ball milling: Weighed calcined coal gangue powder, rare earth tailings powder, lanthanum carbonate or cerium carbonate powder are added to a ball mill and stirred for wet ball milling. The discharged material is then dried. S3. Sintering and Crushing: The material dried in S2 is sintered at high temperature, then crushed and sieved to obtain solid waste rare earth powder. The sintering temperature is 950~1300℃ and the holding time is 1~3h.

2. The high thermal shock resistant rare earth composite high-strength heat-storing refractory brick for hot blast stoves according to claim 1, characterized in that, The aggregate high-alumina bauxite clinker comprises the following raw materials in parts by weight: 15-25 parts of 5-3mm high-alumina bauxite clinker, 15-25 parts of 3-1mm high-alumina bauxite clinker, 10-25 parts of 1-0mm high-alumina bauxite clinker, and 5-17 parts of 200-mesh high-alumina bauxite clinker fine powder.

3. The high thermal shock resistant rare earth composite high-strength heat-storing refractory brick for hot blast stoves according to claim 1, characterized in that, The soft clay is specifically at least one of Su clay and Guangxi white clay; the thermally expandable and volume-stable fine powder is specifically a mixture of andalusite powder and sillimanite powder, and the mass ratio of andalusite powder to sillimanite powder is 4:3 to 9:

2.

4. The high thermal shock resistant rare earth composite high-strength heat-storing refractory brick for hot blast stoves according to claim 1, characterized in that, The binding slurry is specifically made from lignin and tap water in a mass ratio of 1:2.11~2.

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5. A method for preparing a high thermal shock resistant rare earth composite high-strength heat-storing refractory brick for a hot blast stove according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Weighing of ingredients: Weigh the following raw materials in parts by weight: 40-65 parts of calcined coal gangue, 30-40 parts of rare earth tailings, and 5-20 parts of lanthanum carbonate or cerium carbonate powder. S2. Wet ball milling: Weighed calcined coal gangue powder, rare earth tailings powder, lanthanum carbonate or cerium carbonate powder are added to a ball mill and stirred for wet ball milling. The discharged material is then dried. S3, Sintering and Crushing: The material dried in S2 is sintered at high temperature, then crushed and sieved to obtain solid waste rare earth powder. S4. Thoroughly and evenly mix the lignin binder and water to obtain the binder slurry; S5. Ingredients: Weigh the raw materials according to the proportions of the high thermal shock resistant rare earth composite high-strength heat storage refractory bricks for hot blast stoves as described in any one of claims 1-4. S6. Mixing and stirring: Mix the weighed high-alumina bauxite clinker; at the same time, add secondary aluminum ash powder, solid waste rare earth powder, soft clay, thermally expanding volume-stabilized fine powder, and binding slurry in sequence and stir thoroughly. After stirring, let stand for later use. S7. Pressing and molding: Press the mixed raw materials after they have been left to stand into high-alumina refractory bricks to obtain a semi-finished product. S8. Baking: Place the prepared semi-finished product into an oven for baking. After baking, remove it from the oven after it has cooled naturally. S9. Calcination process: Alumina powder is evenly spread in an energy-saving box furnace, and then the dried semi-finished product is placed in the energy-saving box furnace for calcination. S10. Finished product: After firing, the high-alumina refractory brick sample is naturally cooled to room temperature and taken out to obtain a high thermal shock resistant rare earth composite high-strength heat storage refractory brick for hot blast stoves made from solid waste and rare earth tailings.

6. The method for preparing a high thermal shock resistant rare earth composite high-strength heat-storing refractory brick for a hot blast stove according to claim 5, characterized in that, In S2, the material-to-water ratio in wet ball milling is 1 / 6, and the stirring time is 15-20 minutes. The sintering temperature in S3 is 950~1300℃, and the holding time is 1~3h. After cooling, it is put into a crusher for crushing and then passed through a 200-mesh sieve. In S4, the lignin binder and water are mixed in a mass ratio of 1:2.11~2.

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7. The method for preparing a high thermal shock resistant rare earth composite high-strength heat storage refractory brick for a hot blast stove according to claim 5, characterized in that, Before the S5 batching, the raw material grading needs to be carried out: different particle size grading is determined for the aggregates high-alumina bauxite clinker, secondary alumina powder, solid waste rare earth powder, soft clay, and thermally expandable volume-stable fine powder. The aggregate high-alumina bauxite clinker is selected from 5-3mm high-alumina bauxite clinker, 3-1mm high-alumina bauxite clinker, 1-0mm high-alumina bauxite clinker, and 200-mesh high-alumina bauxite clinker fine powder; the solid waste rare earth powder is selected from 200-mesh; the secondary aluminum ash powder is selected from 200-mesh; the soft clay is selected from 200-mesh; and the thermally expanding volume-stable fine powder includes andalusite powder from 200-mesh and sillimanite powder from 325-mesh. In S5, the high-alumina bauxite clinker aggregate is prepared according to the following weight fractions: 15-25 parts of 5-3mm high-alumina bauxite clinker, 15-25 parts of 3-1mm high-alumina bauxite clinker, 10-25 parts of 1-0mm high-alumina bauxite clinker, and 5-17 parts of 200-mesh high-alumina bauxite clinker fine powder; the thermally expandable volume-stabilized fine powder is prepared according to the mass ratio of andalusite powder and sillimanite powder of 4:3-9:

2.

8. The method for preparing a high thermal shock resistant rare earth composite high-strength heat-storing refractory brick for a hot blast stove according to claim 5, characterized in that, S6 aggregate mixing time: 1~3 min, fine powder mixing time: 2~3 min. The fine powder is composed of secondary aluminum ash powder, solid waste rare earth powder, soft clay, and thermally expandable volume-stabilized fine powder. After the aggregate is mixed evenly, it is mixed with the fine powder for 2~3 min. Finally, the prepared binding slurry is added and mixed for 4~6 min. After mixing, it is put into bags and left to stand for 1h~5h before use. The molding pressure in S7 is 137MPa, and the molding rate is ≥98%. The baking temperature in S8 is 110℃, the baking time is 24h~48h, and it needs to be baked until the moisture content is less than 2%.

9. The method for preparing a high thermal shock resistant rare earth composite high-strength heat-storing refractory brick for a hot blast stove according to claim 5, characterized in that, The specific calcination conditions for S9 are as follows: heating for 0.5 hours between room temperature and 80°C, followed by holding for 0.5 to 1 hour; heating for 1 to 1.5 hours between 80 and 500°C, followed by holding for 1 to 2 hours; heating for 1 to 1.5 hours between 800 and 1100°C, followed by holding for 1 to 2 hours; heating for 1 to 1.5 hours between 1100°C and the highest temperature, followed by holding for 5 to 6 hours at the highest temperature of 1450°C to 1520°C.

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