Forsterite-magnesium aluminate spinel refractory brick and preparation method thereof

Abstract

The invention relates to the field of refractory materials, in particular to a forsterite-magnesium aluminate spinel refractory brick and a preparation method thereof, and the forsterite-magnesium aluminate spinel refractory brick is prepared from the following raw materials in parts by mass: 40-70 parts of forsterite-magnesium aluminate spinel, 20-50 parts of magnesia, 0-20 parts of magnesium aluminate spinel and 2-5 parts of a binding agent. According to the invention, one or two of calcium lignosulphonate and dextrin aqueous solution are used as the binding agent, so that the thermal stress generated by the refractory material during temperature change can be buffered, and the compactness, refractoriness and thermal shock resistance of the material are improved. The prepared refractory brick has the advantages of excellent refractoriness, low thermal conductivity, thermal shock resistance, slag corrosion resistance and long service life, and can be widely applied to the fields of metallurgy, chemical industry, building materials and the like.

Description

Technical Field

[0001] This invention relates to the field of refractory materials, specifically to a magnesium olivine-magnesium aluminum spinel refractory brick and its preparation method. Background Technology

[0002] Refractory materials are fundamental materials for ensuring the smooth operation of high-temperature industrial production in metallurgy, building materials, and chemical industries. Their performance directly affects the service life, operating efficiency, and product quality of thermal equipment such as kilns. Among the many refractory materials, magnesia refractories are widely used due to their excellent high-temperature resistance and resistance to alkaline slag erosion.

[0003] In magnesia refractory systems, forsterite (Mg2SiO4) is an important refractory raw material, attracting much attention due to its extremely high refractoriness (melting point above 1890℃), good resistance to acid slag erosion, and low thermal conductivity. However, forsterite itself has inherent defects such as poor thermal shock stability and a narrow firing temperature range. These defects result in a low yield rate of refractory bricks made solely from forsterite during production, and they are prone to cracking and spalling under drastic temperature fluctuations, limiting their application in more demanding conditions and thus restricting their overall cost-effectiveness.

[0004] Magnesium aluminum spinel (MgAl2O4) is another high-performance advanced refractory material, renowned for its excellent resistance to alkali erosion, high thermal stability, low thermal expansion rate, and good impermeability. At high temperatures, its crystal structure is stable and does not easily decompose. However, the high production cost of pure spinel refractories significantly hinders their large-scale application. Furthermore, pure spinel exhibits insufficient toughness, susceptibility to brittle fracture and spalling in the low-to-medium temperature range below 1000℃, which also affects its reliability in kilns requiring frequent start-ups and shutdowns.

[0005] To maximize strengths and minimize weaknesses, the industry generally adopts a composite approach, combining refractory raw materials with different properties to obtain refractory products with superior overall performance. However, existing composite technologies often fail to fully leverage the synergistic effects of each component. On one hand, insufficient optimization of the particle size distribution (i.e., the proportion of particles of different sizes) of the raw materials results in the inability to form the densest packing structure after firing, leading to high porosity and insufficient strength. On the other hand, existing binder systems have limited effectiveness in improving the thermal shock resistance of materials.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The primary objective of this invention is to provide a magnesium olivine-magnesium aluminum spinel refractory brick, which features a low coefficient of thermal expansion, excellent alkali resistance, and low thermal conductivity. It can be applied to refractory materials used in metallurgy, non-ferrous metals, glass, and cement kilns, and offers energy-saving and consumption-reducing effects.

[0008] The magnesium olivine-magnesium aluminum spinel refractory brick provided by this invention is prepared from raw materials comprising the following parts by weight: 40-70 parts of magnesium olivine-magnesium aluminum spinel, 20-50 parts of magnesia, 0-20 parts of magnesium aluminum spinel, and 2-5 parts of binder; Preferably, the binder is selected from one or two of calcium lignosulfonate and dextrin aqueous solution, and more preferably, the binder is calcium lignosulfonate.

[0009] The dextrin aqueous solution has a specific gravity of 1.1 to 1.2, preferably 1.15.

[0010] Using the above-mentioned binder helps to fill the pores in the refractory material, reduce the porosity, and make the carbon network structure formed after carbonization have a certain degree of flexibility and elasticity (the binding effect of calcium lignosulfonate is more prominent).

[0011] Preferably, the forsterite-magnesium aluminum spinel refractory brick is prepared from the following raw materials in parts by weight: 45-60 parts forsterite-magnesium aluminum spinel, 30-45 parts magnesia, 5-20 parts for magnesium aluminum spinel, and 2-5 parts calcium lignosulfonate. More preferably, the magnesium olivine-magnesium aluminum spinel refractory brick is prepared from raw materials comprising the following parts by weight: 45-55 parts magnesium olivine-magnesium aluminum spinel, 35-45 parts magnesia, 10-20 parts magnesium aluminum spinel, and 2-4 parts calcium lignosulfonate.

[0012] According to the present invention, a forsterite-magnesia-alumina spinel refractory brick is provided, wherein preferably, the forsterite-magnesia-alumina spinel contains 48-52% MgO, 36-40% SiO2, and 3-8% Al2O3 by mass, and the bulk density of forsterite is ≥2.70 g / cm³. 3 Using this type of magnesium olivine-magnesium aluminum spinel helps improve the refractoriness and thermal shock stability of refractory materials, thereby ensuring the service life of refractory bricks.

[0013] More preferably, the magnesium olivine-magnesium aluminum spinel is prepared by a method including the following steps: magnesium sand tailings and grade III raw bauxite are prepared in a mass ratio of 85~95:5~15, and then ball-milled with water to obtain the first raw material; The first raw material is vacuum filtered and then dried to obtain a semi-dry second raw material. The second raw material is pressed into shape, dried, and then sintered. The sintering process includes: first heating the temperature to 180-220°C at a heating rate of 3-6°C / min, then heating the temperature to 1350-1450°C at a heating rate of 8-12°C / min, and holding the temperature for 2-4 hours.

[0014] The drying process can be carried out by natural air drying or by heating device. When drying the first raw material, it is advisable to control the moisture content to about 3% (e.g., 2-5%, especially 3-4%). ​​When drying the second raw material after pressing and molding, it is advisable to control the moisture content to below 1%.

[0015] By using the forsterite-magnesium aluminum spinel described in this invention, the synergistic effect of "high refractoriness, high toughness, and low cost" of the two can be fully utilized: the micro-expansion of spinel is used to fill the micro-cracks in the forsterite matrix, thereby improving thermal shock resistance; forsterite partially replaces high-purity spinel, reducing raw material costs and disposing of solid waste.

[0016] Preferably, the particle size of magnesium olivine-magnesium aluminum spinel, magnesia, and magnesium aluminum spinel does not exceed 5 mm; more preferably, the particle size of magnesia and magnesium aluminum spinel does not exceed 3 mm.

[0017] According to the present invention, a forsterite-magnesium aluminum spinel refractory brick is provided, wherein the forsterite-magnesium aluminum spinel, magnesia, and magnesium aluminum spinel contain particles in the following particle size range: (a) 3 mm ≤ d1 < 5 mm; 0 - 5 parts by weight; (b) 1 mm ≤ d2 < 3 mm; 15-35 parts by weight (c) 0.074 mm ≤ d3 < 1 mm; 10-15 parts by weight; (d) d4 < 0.074 mm; 0-15 parts by mass.

[0018] In some embodiments, the grain size distribution of the forsterite-magnesium aluminum spinel is: 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm in a mass ratio of 0~5:15~35:10~15:0~15.

[0019] According to the present invention, a magnesium olivine-magnesium aluminum spinel refractory brick is provided, wherein the magnesia contains MgO with a mass content ≥ 97.0%; and / or the particle size d of the magnesium aluminum spinel is in the range of 0 < d ≤ 5 mm.

[0020] According to the present invention, a forsterite-magnesia-alumina spinel refractory brick is provided, wherein the mass content of MgO in the forsterite-alumina spinel is ≥28.0%, the mass content of Al2O3 is ≥64.0%, and / or the particle size d of the forsterite-alumina spinel is in the range of 0 < d ≤ 5 mm. Selecting this type of forsterite-alumina spinel has the advantage of a better compatibility between the magnesium-rich spinel and forsterite, placing the forsterite phase in the three-phase diagram of the forsterite-magnesia-alumina spinel refractory brick, thereby making the structure of the forsterite-magnesia-alumina spinel refractory brick more stable.

[0021] The forsterite-magnesia-alumina spinel refractory brick provided by the present invention, based on forsterite-magnesia-alumina spinel, magnesia sand and forsterite spinel, has the following four particle size ranges satisfying the following: 3 mm ≤ d1 < 5 mm, 5%; 1 mm ≤ d2 < 3 mm, 25%~35%; 0.074 mm ≤ d3 < 1 mm, 25%~35%; d4 < 0.074 mm, 35%.

[0022] In some preferred embodiments of the present invention, the particle size distribution of the magnesia is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm is 0~5:0~10:5~10:20~25; more preferably, the mass ratio is 0~5:0~10:5~10:20~25, especially 0:10:10:25. In some preferred embodiments of the present invention, the particle size distribution of the magnesium aluminum spinel is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm and 0mm<d4<0.074mm is 0~5:0~10:0~10:0~10, and not all of them are 0; preferably, only one or two of the above three particle size ranges are used, such as only 0mm<d4<0.074mm, or only 0.074mm≤d3<1mm, or both 1mm≤d2<3mm and 0.074mm≤d3<1mm are used (a suitable ratio is 1:1).

[0023] In some preferred embodiments of the present invention, the specific formula of the magnesium olivine-magnesium aluminum spinel refractory brick is as follows: 45-55 parts magnesium olivine-magnesium aluminum spinel, 35-45 parts magnesia, 10-20 parts magnesium aluminum spinel, and 2-4 parts calcium lignosulfonate. The grain size distribution of forsterite-magnesium aluminum spinel is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm and 0mm<d4<0.074mm is 0~5:15~35:10~15:0~15; The particle size distribution of magnesia is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm and 0mm<d4<0.074mm is 0~5:0~10:5~10:20~25; The particle size distribution of magnesium aluminum spinel is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm and 0mm<d4<0.074mm is 0~5:0~10:0~10:0~10, and they are not all 0 at the same time.

[0024] The present invention also provides a method for preparing the forsterite-magnesium aluminum spinel refractory brick, comprising the following steps: mixing forsterite-magnesium aluminum spinel, silica powder and binder according to the specified ratio.

[0025] The method for preparing a magnesium olivine-magnesium aluminum spinel refractory brick according to the present invention preferably includes the following steps: 1) According to the formula, the forsterite-magnesium aluminum spinel powder with a particle size <0.074mm, magnesium aluminum spinel and magnesia sand are mixed to obtain mixture 1; 2) Mix magnesium olivine-magnesium aluminum spinel with a particle size greater than or equal to 0.074 mm, and magnesium aluminum spinel and magnesia aggregate for 5 to 15 minutes. Then add a binder and continue mixing until uniform. Then add the mixture to the mixture 1 and continue mixing to obtain mixture 2.

[0026] Furthermore, the preparation method further includes: 3) Press the mixture 2 on a hydraulic press at 100MPa±10MPa, and then place it in a forced-air drying oven at a constant temperature of 100~120℃ for 20~32 hours; 4) Place the dried sample in a high-temperature box-type resistance furnace, first raise the temperature to 200℃ at a rate of 4~6℃ / min, then raise it to 1400℃ at a rate of 8-12℃ / min, and hold it at that temperature for 3~6 hours, then cool it with the furnace.

[0027] In some preferred embodiments provided by the present invention, steps 3) and 4) are specifically as follows: 3) Press the well-mixed materials into shape on a hydraulic press at 100MPa; place the shaped materials into a forced-air drying oven and dry at a constant temperature of 110℃ for 24 hours.

[0028] 4) Place the dried sample in a high-temperature box-type resistance furnace, first raise the temperature to 200°C at a rate of 5°C / min, then raise it to 1450°C at a rate of 10°C / min, and hold it at that temperature for 4 hours. Cool the sample with the furnace to obtain the final product.

[0029] The beneficial effects of this invention are at least as follows: 1. This invention uses calcium lignosulfonate and dextrin aqueous solution as binders. Taking calcium lignosulfonate as an example, it can maintain high strength for the sample at low temperatures, preventing damage during material handling and drying. In addition, it can undergo pyrolysis at high temperatures without significantly introducing impurities.

[0030] 2. Magnesia olivine-magnesia alumina spinel has good high temperature resistance and chemical stability. When combined with magnesia sand and magnesium alumina spinel in a certain ratio (especially with the control of particle size range), it further improves the overall performance of refractory materials and has a positive impact on apparent porosity, compressive strength, thermal shock resistance and thermal conductivity.

[0031] 3. The refractory bricks prepared by this invention have excellent refractoriness, low thermal conductivity, thermal shock resistance and slag erosion resistance, and long service life. They can be widely used in metallurgy, chemical industry, building materials and other fields. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0033] Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Instruments and other equipment whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels. Unless otherwise specified, the methods described are conventional methods, and the raw materials mentioned are all obtainable from publicly available commercial sources (e.g., magnesia and magnesium aluminum spinel, various binders). Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions.

[0034] In the following example, the forsterite-spinel material is a forsterite refractory material prepared using magnesia tailings. Magnesia tailings and grade III bauxite are placed in a ball mill jar at a mass ratio of 93:7, water is added until the mixture is suitable, and the mixture is ball-milled at 60 r / min for 2 hours to form a homogeneous raw material. Filtration: The homogeneous raw material is introduced into a filter press for vacuum filtration to squeeze out excess water, obtaining a semi-dry homogeneous raw material. This raw material is then placed in a dry place at room temperature for natural drying (until the moisture content is controlled at 3%). Molding: The filter-dried raw material is pressed into shape on a hydraulic press at 100 MPa, and then further dried until the moisture content is less than 1%. Sintering: The dried sample is placed in a high-temperature box-type resistance furnace, first heated to 200℃ at a heating rate of 5℃ / min, then heated to 1400℃ at a heating rate of 10℃ / min, and held at that temperature for 3 hours. The final product is obtained by furnace cooling.

[0035] In the forsterite-magnesium aluminum spinel, the mass content of MgO is 50%, the mass content of SiO2 is 38%, and the mass content of Al2O3 is 9%.

[0036] In magnesia, the mass content of MgO is ≥97.0%.

[0037] In magnesium aluminum spinel, the mass content of MgO is ≥43.0% and the mass content of Al2O3 is ≥52.0%.

[0038] Example 1 This embodiment provides a magnesium olivine-magnesium aluminum spinel refractory brick with the following formula: 55 parts magnesium olivine-magnesium aluminum spinel, 45 parts magnesia, 0 parts magnesium aluminum spinel, and 2 parts calcium lignosulfonate binder.

[0039] The particle size distribution of forsterite-magnesium aluminum spinel is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm is 5:25:15:10. The particle size distribution of magnesia is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm is 0:10:10:25.

[0040] This embodiment also provides a method for preparing the above-mentioned forsterite-magnesia-alumina spinel refractory brick, including the following steps: 1) Prepare the synthetic magnesium olivine-magnesium aluminum spinel, magnesia, magnesium aluminum spinel and binder according to the formula; 2) Mix magnesium olivine-magnesium aluminum spinel, magnesia sand and magnesium aluminum spinel with a particle size <0.074mm on a roller mill to obtain a mixture. 3) Mix magnesium olivine-magnesium aluminum spinel, magnesium aluminum spinel and magnesia aggregate with a particle size greater than or equal to 0.074 mm on a roller mill for 5 to 15 minutes. Then add the binder and continue mixing for 5 minutes until the mixture is uniform. Then add the mixture from step 2) and continue mixing until uniform.

[0041] 4) Press the well-mixed mixture into shape on a hydraulic press at 100MPa.

[0042] 5) Place the shaped raw material into a forced-air drying oven and dry it at a constant temperature of 110℃ for 24 hours.

[0043] 6) Place the dried sample in a high-temperature box-type resistance furnace, first raise the temperature to 200°C at a rate of 5°C / min, then raise it to 1400°C at a rate of 10°C / min, and hold it at that temperature for 4 hours. Cool the sample in the furnace to obtain the final product.

[0044] The performance of the refractory bricks described in this embodiment was tested, and the test results are shown in Table 1: Table 1. Performance indicators of the refractory bricks described in Example 1

[0045] Note: The specific testing conditions are indicated in parentheses in the test results section, and the same applies below.

[0046] Example 2 This embodiment provides a magnesium olivine-magnesium aluminum spinel refractory brick, which is prepared from the following raw materials in parts by weight: 45 parts magnesium olivine-magnesium aluminum spinel, 35 parts magnesia, 20 parts magnesium aluminum spinel, and 4 parts calcium lignosulfonate binder.

[0047] The particle size distribution of the forsterite-magnesia-alumina spinel is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm is 5:15:15:10. The particle size distribution of the magnesia is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm is 0:0:10:25. The particle size distribution of the magnesium-alumina spinel is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm is 0:10:10:0.

[0048] The performance of the refractory bricks described in this embodiment was tested, and the test results are shown in Table 2: Table 2. Performance indicators of the refractory bricks described in Example 2

[0049] Example 3 The preparation method of this embodiment is basically the same as that of Example 1, except that the amount of 0-0.074mm magnesium olivine spinel is reduced and the amount of 0-0.074mm magnesia is increased.

[0050] This embodiment provides a magnesium olivine-magnesium aluminum spinel refractory brick, which is prepared from the following raw materials in parts by weight: 45 parts magnesium olivine-magnesium aluminum spinel, 45 parts magnesia, 10 parts magnesium aluminum spinel, and 3 parts calcium lignosulfonate binder.

[0051] The particle size distribution of forsterite-magnesia-alumina spinel is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm is 5:25:15:0. The particle size distribution of magnesia is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm is 0:10:10:25. The particle size distribution of magnesium-alumina spinel is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm is 0:0:0:10.

[0052] The performance of the refractory bricks described in this embodiment was tested, and the test results are shown in Table 3: Table 3. Performance indicators of the refractory bricks described in Example 3

[0053] Example 4 The preparation method of this embodiment is basically the same as that of Example 1, except that it is prepared from the following raw materials in parts by weight: 45 parts of magnesium olivine-magnesium aluminum spinel, 45 parts of magnesia, 10 parts of magnesium aluminum spinel, and 4 parts of calcium lignosulfonate binder.

[0054] The particle size distribution of the forsterite-magnesia-alumina spinel is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm is 5:15:15:10. The particle size distribution of the magnesia is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm is 0:10:10:25. The particle size distribution of the magnesium-alumina spinel is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm is 0:0:10:0.

[0055] The performance of the refractory bricks described in this embodiment was tested, and the test results are shown in Table 4: Table 4. Performance indicators of the refractory bricks described in Example 4

[0056] Example 5 The preparation method of this embodiment is basically the same as that of Example 1, except that it is prepared from the following raw materials in parts by weight: 70 parts magnesium olivine-magnesium aluminum spinel, 30 parts magnesia, 0 parts magnesium aluminum spinel, and 3 parts calcium lignosulfonate binder.

[0057] The particle size distribution of the forsterite-magnesia-alumina spinel is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm is 5:35:15:15. The particle size distribution of the magnesia is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm is 0:0:10:20.

[0058] The performance of the refractory bricks described in this embodiment was tested, and the test results are shown in Table 5: Table 5. Performance indicators of the refractory bricks described in Example 5

[0059] Example 6 The only difference from Example 3 is that the dextrin aqueous solution with a specific gravity of 1.15 is used in an amount of 3%.

[0060] The performance of the refractory bricks described in this embodiment was tested, and the test results are shown in Table 6: Table 6. Performance indicators of the refractory bricks described in Example 6

[0061] In the above embodiments, each embodiment exhibits excellent resistance to clinker erosion and alkali erosion, with Embodiment 3 showing even better overall performance.

[0062] Comparative Example 1 The same method as in Example 3 was used for preparation, the only difference being that pure water was used for bonding, with 45 parts of olivine-magnesium aluminum spinel, 45 parts of magnesia, and 10 parts of magnesia aluminum spinel. The olivine-spinel particle size distribution was as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm was 5:25:15:0. The magnesia particle size distribution was as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm was 0:10:10:25. The particle size distribution of magnesium aluminum spinel is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm and 0mm<d4<0.074mm is 0:0:0:10.

[0063] The performance of the refractory bricks described in this embodiment was tested, and the test results are shown in Table 7: Table 7. Performance indicators of the refractory bricks described in Comparative Example 1

[0064] The comparative test results show that the calcium lignosulfonate-bonded olivine refractory bricks prepared by this invention have low porosity and higher strength, and the material has better resistance to alkali erosion and wear resistance.

[0065] Comparative Example 2 The same method as in Example 3 was used for preparation, except that pure magnesia was used as the binder, with 100 parts of magnesia. The particle size distribution of the magnesia was as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm, and 0mm<d4<0.074mm was 5:35:25:35.

[0066] The performance of the refractory bricks described in this embodiment was tested, and the test results are shown in Table 8: Table 8. Performance indicators of the refractory bricks described in Comparative Example 2

[0067] The comparative test results show that the calcium lignosulfonate-bonded olivine refractory brick prepared by this invention has similar performance to traditional magnesia bricks, but has better thermal shock resistance and lower thermal conductivity.

[0068] Comparative Example 3 Compare the properties of a magnesium olivine refractory brick purchased from the market. Table 9 shows the comparison.

[0069] Table 9. Performance indicators of the refractory bricks described in Comparative Example 5

[0070] The comparative test results show that most of the natural olivine refractory bricks sold on the market are porous, lightweight, and heat-insulating refractory materials. Although they have low thermal conductivity, their compressive strength, load softening temperature, and thermal shock resistance are inferior to the refractory bricks in Example 3, and they cannot be used as working layers.

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A forsterite-magnesia-alumina spinel refractory brick, characterized in that, It is prepared from the following raw materials in parts by weight: 40-70 parts of magnesium olivine-magnesium aluminum spinel, 20-50 parts of magnesia, 0-20 parts of magnesium aluminum spinel, and 2-5 parts of binder. Preferably, the binder is selected from one or two of calcium lignosulfonate and dextrin aqueous solution.

2. The forsterite-magnesia-alumina spinel refractory brick according to claim 1, characterized in that, It is prepared from the following raw materials in parts by weight: 45-60 parts of magnesium olivine-magnesium aluminum spinel, 30-45 parts of magnesia, 5-20 parts of magnesium aluminum spinel, and 2-5 parts of calcium lignosulfonate. The preferred composition is 45-55 parts magnesium olivine-magnesium aluminum spinel, 35-45 parts magnesia, 10-20 parts magnesium aluminum spinel, and 2-4 parts calcium lignosulfonate.

3. The forsterite-magnesia-alumina spinel refractory brick according to claim 1 or 2, characterized in that, In the forsterite-magnesium aluminum spinel, the mass content of MgO is 48-52%, the mass content of SiO2 is 36-40%, the mass content of Al2O3 is 3-8%, and the bulk density of forsterite is ≥2.70 g / cm³. 3 ; Preferably, the forsterite-spinel is prepared by a method including the following steps: magnesia tailings and grade III bauxite are prepared in a mass ratio of 85~95:5~15, and then ball-milled with water to obtain the first raw material; The first raw material is vacuum filtered and then dried to obtain a semi-dry second raw material. The second raw material is pressed into shape, dried, and then sintered. The sintering process includes: first heating the temperature to 180-220°C at a heating rate of 3-6°C / min, then heating the temperature to 1350-1450°C at a heating rate of 8-12°C / min, and holding the temperature for 2-4 hours.

4. The forsterite-magnesia-alumina spinel refractory brick according to any one of claims 1-3, characterized in that, The forsterite-magnesium aluminum spinel contains particles in the following four size ranges: (a) 3 mm ≤ d1 < 5 mm: 0 - 5 parts by weight; (b) 1 mm ≤ d2 < 3 mm: 15-35 parts by weight; (c) 0.074 mm ≤ d3 < 1 mm: 10-15 parts by weight; (d) d4 < 0.074 mm: 0-15 parts by weight.

5. The forsterite-magnesia-alumina spinel refractory brick according to any one of claims 1-4, characterized in that, The magnesia contains MgO with a mass content of ≥97.0%; and / or the particle size d of the magnesium aluminum spinel is in the range of 0 < d ≤ 5 mm.

6. The forsterite-magnesia-alumina spinel refractory brick according to any one of claims 1-4, characterized in that, In the magnesium aluminum spinel, the mass content of MgO is ≥28.0%, and the mass content of Al2O3 is ≥64.0%; and / or, the particle size d of the magnesium aluminum spinel is in the range of 0 < d ≤ 5 mm.

7. The forsterite-magnesia-alumina spinel refractory brick according to any one of claims 1-6, characterized in that, Based on forsterite-magnesium aluminum spinel, magnesia and magnesium aluminum spinel, the following four particle size ranges satisfy the following conditions: 3 mm ≤ d1 < 5 mm, 5%; 1 mm ≤ d2 < 3 mm, 25%~35%; 0.074 mm ≤ d3 < 1 mm, 25%~35%; d4 < 0.074 mm, 35%.

8. The forsterite-magnesia-alumina spinel refractory brick according to any one of claims 1-7, characterized in that, The formula is as follows: 45-55 parts of magnesium olivine-magnesium aluminum spinel, 35-45 parts of magnesia, 10-20 parts of magnesium aluminum spinel, and 2-4 parts of calcium lignosulfonate. The grain size distribution of forsterite-magnesium aluminum spinel is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm and 0mm<d4<0.074mm is 0~5:15~35:10~15:0~15; The particle size distribution of magnesia is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm and 0mm<d4<0.074mm is 0~5:0~10:5~10:20~25; The particle size distribution of magnesium aluminum spinel is as follows: the mass ratio of 3mm≤d1<5mm, 1mm≤d2<3mm, 0.074mm≤d3<1mm and 0mm<d4<0.074mm is 0~5:0~10:0~10:0~10, and they are not all 0 at the same time.

9. The method for preparing the forsterite-magnesia-alumina spinel refractory brick according to any one of claims 1-8, characterized in that, Includes the following steps: 1) According to the formula, the forsterite-magnesium aluminum spinel powder with a particle size <0.074mm, magnesium aluminum spinel and magnesia sand are mixed to obtain mixture 1; 2) Mix magnesium olivine-magnesium aluminum spinel with a particle size greater than or equal to 0.074 mm, and magnesium aluminum spinel and magnesia aggregate for 5 to 15 minutes. Then add a binder and continue mixing until uniform. Then add the mixture to the mixture 1 and continue mixing to obtain mixture 2.

10. The method for preparing forsterite-magnesia-alumina spinel refractory bricks according to claim 9, characterized in that, Also includes: 3) Press the mixture 2 on a hydraulic press at 100MPa±10MPa, and then place it in a forced-air drying oven at a constant temperature of 100~120℃ for 20~32 hours; 4) Place the dried sample in a high-temperature box-type resistance furnace, first raise the temperature to 200℃ at a rate of 4~6℃ / min, then raise it to 1400℃ at a rate of 8-12℃ / min, and hold it at that temperature for 3~6 hours, then cool it with the furnace.

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