A low thermal conductivity refractory material and preparation method thereof

Abstract

The present invention provides a low-thermal-conductivity refractory material and a preparation method thereof, belonging to the technical field of refractory materials. The low-thermal-conductivity refractory material provided by the present invention is prepared from the following raw materials in percentage by mass: 60-77% magnesia, 20-37% magnesia-alumina spinel, 2-3% binder, and 0.1-0.2% additive; the additives are kaolin and quartz sand; the binder is one of dextrin solution, calcium lignin sulfonate solution, methyl cellulose solution, and sulfite pulp waste liquid; the mass ratio of kaolin and quartz sand is 1:(1-3). The present invention uses additives kaolin and quartz sand, which will preferentially melt during sintering, thereby forming pores during the sintering process, thereby reducing the thermal conductivity of the refractory material; at the same time, since the amount of additives added is small, the strength of the refractory material will not be affected.

Description

Technical Field

[0001] The present invention belongs to the technical field of refractory materials, and in particular relates to a low thermal conductivity refractory material and a preparation method thereof. Background Art

[0002] In recent years, the main chrome-free refractory material used in cement kilns has been magnesia-alumina spinel bricks. However, magnesia-alumina spinel bricks have certain limitations, such as their high thermal conductivity, which restricts their application. Therefore, how to reduce the thermal conductivity of refractory materials has become a technical challenge that needs to be solved in this field. Summary of the Invention

[0003] The object of the present invention is to provide a low thermal conductivity refractory material and a preparation method thereof. The low thermal conductivity refractory material provided by the present invention has low thermal conductivity.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a low thermal conductivity refractory material, which is prepared from the following raw materials in the following mass percentages:

[0006] 60~77% magnesia, 20~37% magnesia-alumina spinel, 2~3% binder and 0.1~0.2% additive;

[0007] The additives are kaolin and quartz sand;

[0008] The binder is one of dextrin solution, calcium lignin sulfonate solution, methyl cellulose solution and sulfite pulp waste liquid;

[0009] The mass ratio of the kaolin and quartz sand is 1: (1-3).

[0010] Preferably, it is prepared from the following raw materials in percentage by mass:

[0011] Magnesia 65~72%, magnesia-alumina spinel 25~32%, binder 2~3% and additives 0.15~0.2%.

[0012] Preferably, the magnesia includes magnesia particles and magnesia fine powder, the particle size of the magnesia particles is 0.063-5 mm, and the particle size of the magnesia fine powder is less than 0.063 mm.

[0013] Preferably, the mass ratio of the magnesia particles to the magnesia fine powder is (1-3):1.

[0014] Preferably, the particle size of the magnesia-alumina spinel is 0.063-3 mm.

[0015] The present invention also provides a method for preparing the low thermal conductivity refractory material described in the above technical solution, comprising the following steps:

[0016] (1) Mixing the additive and a portion of the binder to obtain additive particles;

[0017] (2) mixing the additive particles, magnesia, magnesia-alumina spinel and the remaining binder obtained in step (1) to obtain a mixed material;

[0018] (3) forming the mixture obtained in step (2) to obtain a brick;

[0019] (4) Sintering the bricks obtained in step (3) to obtain a low thermal conductivity refractory material.

[0020] Preferably, the particle size of the additive particles in step (1) is 0.1-0.5 mm.

[0021] Preferably, the molding pressure in step (3) is 15-20 kN / cm 2 .

[0022] Preferably, the sintering temperature in step (4) is 1600-1800° C., and the sintering time is 5-12 hours.

[0023] The present invention provides a low-thermal-conductivity refractory material prepared from the following raw materials in percentage by weight: 60-77% magnesia, 20-37% magnesia-alumina spinel, 2-3% binder, and 0.1-0.2% additives; the additives are kaolin and quartz sand; the binder is one of a dextrin solution, a calcium lignin sulfonate solution, a methylcellulose solution, and sulfite pulp waste liquor; and the mass ratio of kaolin to quartz sand is 1:(1-3). The kaolin and quartz sand additives used in the present invention preferentially melt during sintering, forming pores during the sintering process and reducing the thermal conductivity of the refractory material. Furthermore, the small amount of additives added does not affect the strength of the refractory material. Experimental results show that the thermal conductivity (1000°C) of the low-thermal-conductivity refractory material provided by the present invention is 1.903-2.012 W / m·K. DETAILED DESCRIPTION

[0024] The present invention provides a low thermal conductivity refractory material, which is prepared from the following raw materials in the following mass percentages:

[0025] 60~77% magnesia, 20~37% magnesia-alumina spinel, 2~3% binder and 0.1~0.2% additive;

[0026] The additives are kaolin and quartz sand;

[0027] The binder is one of dextrin solution, calcium lignin sulfonate solution, methyl cellulose solution and sulfite pulp waste liquid;

[0028] The mass ratio of the kaolin and quartz sand is 1: (1-3).

[0029] The present invention has no particular limitation on the sources of the raw materials, and commercially available products known to those skilled in the art may be used.

[0030] The raw materials for preparing the low thermal conductivity refractory material provided by the present invention include 60-77% magnesia by mass; the magnesia preferably comprises magnesia particles and magnesia fine powder; the particle size of the magnesia particles is preferably 0.063-5 mm; the particle size of the magnesia fine powder is preferably less than 0.063 mm; and the mass ratio of the magnesia particles to the magnesia fine powder is preferably (1-3):1. In the present invention, by controlling the content of magnesia, it can be combined with other ingredients to ensure the mineral stability and volume stability of the refractory material, thereby improving the mechanical flexibility of the refractory material. By controlling the mass ratio of magnesia particles to magnesia fine powder in the magnesia, the mechanical flexibility of the refractory material can be further improved.

[0031] In the present invention, the magnesia preferably includes fused magnesia and / or sintered magnesia; the mass percentage of MgO in the magnesia is preferably ≥96%.

[0032] In the present invention, the particle size of the magnesia particles is preferably distributed in a gradient; in terms of mass percentage, the gradient distribution is preferably 25-30% for 0.063-0.999 mm, 43-48% for 1-2.999 mm, and 24-28% for 3-5 mm. In the present invention, the magnesia particles are added according to particle size gradation, with large particles serving as the skeleton, medium and small particles filling corresponding gaps, and fine magnesia powder filling smaller gaps, thereby improving the density of the refractory material and, in turn, the compressive strength of the refractory material.

[0033] As an embodiment, the mass percentage of the magnesia can be 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75% or 76%.

[0034] The raw materials for preparing the low thermal conductivity refractory provided by the present invention include, by mass percentage, 20-37% magnesia-alumina spinel; the magnesia-alumina spinel preferably comprises sintered spinel and / or fused spinel; the sum of the mass percentages of alumina and magnesia in the magnesia-alumina spinel is preferably ≥ 90%; and the particle size of the magnesia-alumina spinel is preferably 0.063-3 mm. In the present invention, the magnesia-alumina spinel can improve the mechanical flexibility of the refractory.

[0035] As an embodiment, the mass percentage of the magnesium aluminum spinel can be 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35% or 36%.

[0036] The raw materials for preparing the low thermal conductivity refractory material provided herein include, by mass percentage, 2-3% of a binder; the binder is at least one of a dextrin solution, a calcium lignin sulfonate solution, a methylcellulose solution, and sulfite pulp waste liquor. In the present invention, the binder can be directly volatilized during the sintering process and can ensure the initial strength of the brick after forming.

[0037] The present invention has no particular limitation on the concentrations of the dextrin solution, calcium lignin sulfonate solution, methyl cellulose solution and sulfite pulp waste liquor, and any concentration known to those skilled in the art may be used.

[0038] As an embodiment, the mass percentage of the binder may be 2.5%.

[0039] The raw materials used to prepare the low-thermal-conductivity refractory material provided herein include, by mass percentage, 0.1-0.2% additives; the additives are kaolin and quartz sand; the mass ratio of the kaolin to the quartz sand is 1:(1-3). The kaolin and quartz sand additives used in the present invention preferentially melt during sintering, forming pores during the sintering process, thereby reducing the thermal conductivity of the refractory material. Furthermore, the relatively small amount of additives added does not affect the strength of the refractory material. By controlling the mass ratio of kaolin to quartz sand within the above range, the thermal conductivity of the refractory material can be synergistically reduced.

[0040] As an embodiment, the mass percentage of the additive may be 0.11%, 0.12%, 0.13%, 0.14%, 0.15%, 0.16%, 0.17%, 0.18% or 0.19%.

[0041] As an embodiment, the mass ratio of kaolin and quartz sand can be 1:1.5, 1:2 or 1:2.5.

[0042] The present invention has no particular limitation on the particle size of the quartz sand, and any quartz sand well known to those skilled in the art can be used.

[0043] The present invention also provides a method for preparing the low thermal conductivity refractory material described in the above technical solution, comprising the following steps:

[0044] (1) Mixing the additive and a portion of the binder to obtain additive particles;

[0045] (2) mixing the additive particles, magnesia, magnesia-alumina spinel and the remaining binder obtained in step (1) to obtain a mixed material;

[0046] (3) forming the mixture obtained in step (2) to obtain a brick;

[0047] (4) Sintering the bricks obtained in step (3) to obtain a low thermal conductivity refractory material.

[0048] The invention mixes the additive and a part of the binder to obtain the additive particles.

[0049] In the present invention, the mass of the partial binder is preferably 5-10% of the mass of the additive. As an embodiment, the mass of the partial binder can be 6%, 7%, 8% or 9% of the mass of the additive.

[0050] The present invention has no special limitation on the operation of mixing the additive and part of the binder, and the technical scheme for preparing the mixed material well known to those skilled in the art can be adopted.

[0051] In the present invention, the particle size of the additive particles is preferably 0.1 to 0.5 mm. As an embodiment, the particle size of the additive particles can be 0.2 mm, 0.3 mm or 0.4 mm.

[0052] In the present invention, when the particle size of the additive particles does not meet the above particle size requirements, the additive particles are preferably crushed.

[0053] After obtaining the additive particles, the present invention mixes the additive particles, magnesia, magnesia-alumina spinel and the remaining binder to obtain a mixed material.

[0054] The present invention has no special limitation on the operation of mixing the additive particles, magnesia, magnesia-alumina spinel and the remaining binder, and the technical scheme for preparing the mixed material well known to those skilled in the art can be adopted.

[0055] After obtaining the mixed material, the present invention shapes the mixed material to obtain a brick.

[0056] In the present invention, the molding pressure is preferably 15~20kN / cm 2 As an embodiment, the molding pressure can be 16kN / cm 2 , 17kN / cm 2 , 18kN / cm 2 or 19kN / cm 2 .

[0057] The present invention has no particular limitation on the time of the molding, as long as the molding can be performed.

[0058] After the forming is completed, the present invention preferably dries the formed product to obtain a green brick.

[0059] In the present invention, the drying temperature is preferably 120-250° C., more preferably 150-200° C.; the drying time is preferably 48-72 h, more preferably 55-60 h.

[0060] After obtaining the bricks, the present invention sintered the bricks to obtain low thermal conductivity refractory materials.

[0061] In the present invention, the sintering temperature is preferably 1600-1800°C, and the sintering time is preferably 5-12 hours. In one embodiment, the sintering temperature can be 1650°C, 1700°C, or 1750°C, and the sintering time can be 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, or 11 hours. The present invention can form a stable microstructure and mineral phase through sintering.

[0062] The preparation method provided by the invention has simple process.

[0063] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0064] Example 1

[0065] A low thermal conductivity refractory material is prepared from the following raw materials in percentage by mass:

[0066] 60% magnesia, 37% magnesia-alumina spinel, 2.9% binder and 0.1% additive;

[0067] The additives are kaolin and quartz sand;

[0068] The magnesia is magnesia particles and magnesia fine powder;

[0069] The particle size of the magnesia particles is 0.063~5mm;

[0070] The particle size of the magnesia fine powder is less than 0.063 mm;

[0071] The mass ratio of the magnesia particles to the magnesia fine powder is 1:1;

[0072] The magnesia is fused magnesia; the mass percentage of MgO in the magnesia is 97%;

[0073] The particle size of the magnesia particles is distributed in a gradient;

[0074] In terms of mass percentage, the gradient distribution is 0.063-0.999 mm 25%, 1-2.999 mm 48% and 3-5 mm 27%;

[0075] The magnesium-aluminum spinel is fused spinel; the sum of the mass percentages of aluminum oxide and magnesium oxide in the magnesium-aluminum spinel is ≥90%; the particle size of the magnesium-aluminum spinel is 0.063-3 mm;

[0076] The binder is a calcium lignin sulfonate solution; the concentration of the calcium lignin sulfonate solution is 1.23 g / mL;

[0077] The mass ratio of the kaolin and quartz sand is 1:1;

[0078] The kaolin is produced by Guangdong Yongfeng Chemical Co., Ltd.

[0079] The particle size of the quartz sand is 0.1 mm;

[0080] The preparation method of the low thermal conductivity refractory material comprises the following steps:

[0081] (1) Mixing the additive and a portion of the binder to obtain additive particles with a particle size of 0.2 mm; wherein the mass of the portion of the binder is 5% of the mass of the additive;

[0082] (2) mixing the additive particles, magnesia, magnesia-alumina spinel and the remaining binder obtained in step (1) to obtain a mixed material;

[0083] (3) The mixture obtained in step (2) is subjected to a 2 The mold is formed and then dried at 200°C for 60 hours to obtain a brick;

[0084] (4) The bricks obtained in step (3) are sintered at 1600° C. for 6 hours to obtain a low thermal conductivity refractory material.

[0085] Comparative Example 1

[0086] On the basis of Example 1, kaolin was omitted, and other conditions remained unchanged, that is, the additive was only quartz sand, to obtain a low thermal conductivity refractory material.

[0087] Comparative Example 2

[0088] On the basis of Example 1, quartz sand was omitted, and other conditions remained unchanged, that is, the additive was only kaolin, to obtain a low thermal conductivity refractory material.

[0089] The low thermal conductivity refractory materials prepared in Example 1 and Comparative Examples 1-2 were subjected to performance tests, and the results are shown in Table 1; the test standards are: bulk density: GB / T2997; apparent porosity: GB / T2997; room temperature compressive strength: GB / T5072; thermal conductivity: GBT5990.

[0090] Table 1 Performance data of low thermal conductivity refractory materials prepared in Example 1 and Comparative Examples 1-2

[0091]

[0092] As can be seen from Table 1, when the additives only include quartz sand or kaolin, the thermal conductivity of the refractory material will increase, which proves that the use of quartz sand and kaolin in the present invention can synergistically reduce the thermal conductivity of the refractory material.

[0093] Example 2

[0094] On the basis of Example 1, the mass ratio of kaolin and quartz sand was modified to 1:2, and other conditions remained unchanged to obtain a low thermal conductivity refractory material.

[0095] Example 3

[0096] On the basis of Example 1, the mass ratio of kaolin and quartz sand was modified to 1:3, and other conditions remained unchanged to obtain a low thermal conductivity refractory material.

[0097] The low thermal conductivity refractory materials prepared in Examples 1 to 3 were subjected to performance tests, and the results are shown in Table 2. The test standards are: bulk density: GB / T2997; apparent porosity: GB / T2997; room temperature compressive strength: GB / T5072; thermal conductivity: GBT5990.

[0098] Table 2 Performance data of low thermal conductivity refractory materials prepared in Examples 1 to 3

[0099]

[0100] It can be seen from Table 2 that the thermal conductivity of the refractory material can be further reduced by controlling the mass ratio of kaolin and quartz sand. When the mass ratio of kaolin and quartz sand is 1:2, the thermal conductivity is the lowest.

[0101] Comparative Example 3

[0102] On the basis of Example 1, kaolin was changed to bentonite, and other conditions remained unchanged to obtain a low thermal conductivity refractory material.

[0103] Comparative Example 4

[0104] On the basis of Example 1, the quartz sand was changed to silicon powder, and other conditions remained unchanged to obtain a low thermal conductivity refractory material.

[0105] The thermal conductivity of the low thermal conductivity refractory materials prepared in Example 1 and Comparative Examples 3-4 was tested, and the results are shown in Table 3; the thermal conductivity test standard is GBT5990.

[0106] Table 3 Performance data of low thermal conductivity refractory materials prepared in Example 1 and Comparative Examples 3-4

[0107]

[0108] It can be seen from Table 3 that changing kaolin and quartz sand affects the thermal conductivity of the refractory material, resulting in an increase in the thermal conductivity, which proves that the use of kaolin and quartz sand in the present invention can significantly reduce the thermal conductivity of the refractory material.

[0109] Example 4

[0110] A low thermal conductivity refractory material is prepared from the following raw materials in percentage by mass:

[0111] 77% magnesia, 20% magnesia-alumina spinel, 2.8% binder and 0.2% additive;

[0112] The additives are kaolin and quartz sand;

[0113] The magnesia is magnesia particles and magnesia fine powder;

[0114] The particle size of the magnesia particles is 0.063~5mm;

[0115] The particle size of the magnesia fine powder is less than 0.063 mm;

[0116] The mass ratio of the magnesia particles to the magnesia fine powder is 3:1;

[0117] The magnesia is fused magnesia; the mass percentage of MgO in the magnesia is 97%;

[0118] The particle size of the magnesia particles is distributed in a gradient;

[0119] In terms of mass percentage, the gradient distribution is 0.065-0.999 mm 25%, 1-2.999 mm 48% and 3-5 mm 27%;

[0120] The magnesium-aluminum spinel is fused spinel; the sum of the mass percentages of aluminum oxide and magnesium oxide in the magnesium-aluminum spinel is ≥90%; the particle size of the magnesium-aluminum spinel is 0.063-3 mm;

[0121] The binder is a calcium lignin sulfonate solution; the concentration of the calcium lignin sulfonate solution is 1.23 g / mL;

[0122] The mass ratio of the kaolin and quartz sand is 1:1;

[0123] The kaolin is produced by Guangdong Yongfeng Chemical Co., Ltd.

[0124] The particle size of the quartz sand is 0.1 mm;

[0125] The preparation method of the low thermal conductivity refractory material comprises the following steps:

[0126] (1) Mixing the additive and a portion of the binder to obtain additive particles with a particle size of 0.2 mm; wherein the mass of the portion of the binder is 10% of the mass of the additive;

[0127] (2) mixing the additive particles, magnesia, magnesia-alumina spinel and the remaining binder obtained in step (1) to obtain a mixed material;

[0128] (3) The mixture obtained in step (2) is subjected to a 2 The mold is formed and then dried at 200°C for 60 hours to obtain a brick;

[0129] (4) The bricks obtained in step (3) are sintered at 1800° C. for 12 hours to obtain a low thermal conductivity refractory material.

[0130] Example 5

[0131] A low thermal conductivity refractory material is prepared from the following raw materials in percentage by mass:

[0132] 70% magnesia, 27% magnesia-alumina spinel, 2.85% binder and 0.15% additive;

[0133] The additives are kaolin and quartz sand;

[0134] The magnesia is magnesia particles and magnesia fine powder;

[0135] The particle size of the magnesia particles is 0.063~5mm;

[0136] The particle size of the magnesia fine powder is less than 0.063 mm;

[0137] The mass ratio of the magnesia particles to the magnesia fine powder is 2:1;

[0138] The magnesia is fused magnesia; the mass percentage of MgO in the magnesia is 97%;

[0139] The particle size of the magnesia particles is distributed in a gradient;

[0140] In terms of mass percentage, the gradient distribution is 0.065-0.999 mm 25%, 1-2.999 mm 48% and 3-5 mm 27%;

[0141] The magnesium-aluminum spinel is fused spinel; the sum of the mass percentages of aluminum oxide and magnesium oxide in the magnesium-aluminum spinel is ≥90%; the particle size of the magnesium-aluminum spinel is 0.063-3 mm;

[0142] The binder is a calcium lignin sulfonate solution; the concentration of the calcium lignin sulfonate solution is 1.23 g / mL;

[0143] The mass ratio of the kaolin and quartz sand is 1:1;

[0144] The kaolin is produced by Guangdong Yongfeng Chemical Co., Ltd.

[0145] The particle size of the quartz sand is 0.1 mm;

[0146] The preparation method of the low thermal conductivity refractory material comprises the following steps:

[0147] (1) Mixing the additive and a portion of the binder to obtain additive particles with a particle size of 0.2 mm; wherein the mass of the portion of the binder is 8% of the mass of the additive;

[0148] (2) mixing the additive particles, magnesia, magnesia-alumina spinel and the remaining binder obtained in step (1) to obtain a mixed material;

[0149] (3) The mixture obtained in step (2) is subjected to a 2 The mold is formed and then dried at 200°C for 60 hours to obtain a brick;

[0150] (4) The bricks obtained in step (3) are sintered at 1700° C. for 8 hours to obtain a low thermal conductivity refractory material.

[0151] The low thermal conductivity refractory materials prepared in Examples 4 and 5 were subjected to performance tests, and the results are shown in Table 4. The test standards are: bulk density: GB / T2997; apparent porosity: GB / T2997; room temperature compressive strength: GB / T5072; thermal conductivity: GBT5990.

[0152] Table 4 Performance data of low thermal conductivity refractory materials prepared in Examples 4-5

[0153]

[0154] It can be seen from Table 4 that the low thermal conductivity refractory material of the present invention has low thermal conductivity.

[0155] It can be seen from the above embodiments and comparative examples that the low thermal conductivity refractory material provided by the present invention has low thermal conductivity.

[0156] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A low thermal conductivity refractory material, characterized in that: Prepared from the following raw materials in percentage by weight: 60~77% magnesia, 20~37% magnesia-alumina spinel, 2~3% binder and 0.1~0.2% additive; The additives are kaolin and quartz sand; The binder is one of dextrin solution, calcium lignin sulfonate solution, methyl cellulose solution and sulfite pulp waste liquid; The mass ratio of the kaolin and quartz sand is 1: (1-3).

2. The low thermal conductivity refractory material according to claim 1, characterized in that: Prepared from the following raw materials in percentage by weight: Magnesia 65~72%, magnesia-alumina spinel 25~32%, binder 2~3% and additives 0.15~0.2%.

3. The low thermal conductivity refractory material according to claim 1 or 2, characterized in that: The magnesia includes magnesia particles and magnesia fine powder. The particle size of the magnesia particles is 0.063-5 mm, and the particle size of the magnesia fine powder is less than 0.063 mm.

4. The low thermal conductivity refractory material according to claim 3, characterized in that: The mass ratio of the magnesia particles to the magnesia fine powder is (1-3):

1.

5. The low thermal conductivity refractory material according to claim 1 or 2, characterized in that: The particle size of the magnesia-alumina spinel is 0.063-3 mm.

6. The method for preparing the low thermal conductivity refractory material according to any one of claims 1 to 5, characterized in that: The following steps are involved: (1) Mixing the additive and a portion of the binder to obtain additive particles; (2) mixing the additive particles, magnesia, magnesia-alumina spinel and the remaining binder obtained in step (1) to obtain a mixed material; (3) forming the mixture obtained in step (2) to obtain a brick; (4) Sintering the bricks obtained in step (3) to obtain a low thermal conductivity refractory material.

7. The preparation method according to claim 6, characterized in that The particle size of the additive particles in step (1) is 0.1-0.5 mm.

8. The preparation method according to claim 6, characterized in that The molding pressure in step (3) is 15~20kN / cm 2 .

9. The preparation method according to claim 6, characterized in that The sintering temperature in step (4) is 1600-1800° C., and the sintering time is 5-12 hours.

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