A ladle magnesia-carbon brick ramming mix and its preparation method

Abstract

The present invention relates to the technical field of refractory materials, and provides a ramming paste for ladle magnesia-carbon bricks and a preparation method thereof. The raw materials include the following components in parts by weight: 30-40 parts of magnesite, 20-30 parts of cordierite powder, 10-20 parts of kaolin, 5-10 parts of silicon nitride, and 5-10 parts of binder; the binder is composed of pseudoboehmite and magnesium aluminum silicate. Through the above technical solution, the problems of low strength and poor thermal shock resistance of the ramming paste for magnesia-carbon bricks in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of refractories, and specifically, to a mortar for ladle magnesia-carbon bricks and a preparation method thereof. Background Art

[0002] As a composite refractory, magnesia-carbon bricks are often used in parts such as the slag line of ladles. Magnesia-carbon bricks are mainly built using mortar for magnesia-carbon bricks as a binder. The performance of the mortar for magnesia-carbon bricks directly affects the building quality and service life of magnesia-carbon bricks. If the performance of the mortar for magnesia-carbon bricks is poor, the joints of magnesia-carbon bricks are easily washed and eroded during use, resulting in the detachment of magnesia-carbon bricks.

[0003] Currently, the strength of the mortar for magnesia-carbon bricks is low, the thermal shock resistance is poor, it is easy to fall off, and it cannot achieve good bonding with magnesia-carbon bricks, which leads to frequent maintenance of magnesia-carbon brick masonry, wasting manpower and material resources. In order to improve the service life of magnesia-carbon brick masonry, it is of great significance to develop a mortar for magnesia-carbon bricks with high strength and high thermal shock resistance. Summary of the Invention

[0004] The present invention provides a mortar for ladle magnesia-carbon bricks and a preparation method thereof, which solves the problems of low strength and poor thermal shock resistance of the mortar for magnesia-carbon bricks in the related art.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention provides a mortar for ladle magnesia-carbon bricks, and the raw materials include the following components in parts by weight: 30-40 parts of magnesia sand, 20-30 parts of cordierite powder, 10-20 parts of kaolin, 5-10 parts of silicon nitride, and 5-10 parts of binder;

[0007] The binder is composed of pseudoboehmite and magnesium aluminum silicate.

[0008] As a further technical solution, the mass ratio of pseudoboehmite to magnesium aluminum silicate is 3:2 - 4:1.

[0009] When the mass ratio of pseudoboehmite to magnesium aluminum silicate is 3:2 - 4:1, the normal-temperature and high-temperature flexural bonding strength and thermal shock resistance of the mortar for magnesia-carbon bricks can be further improved.

[0010] As a further technical solution, the mass ratio of pseudoboehmite to magnesium aluminum silicate is 7:3.

[0011] As a further technical solution, the silicon nitride is starch-modified silicon nitride, and the preparation method of the starch-modified silicon nitride is: dissolving starch in water, mixing evenly, gelatinizing, adding silicon nitride, dispersing evenly, cooling and drying, and shaking and dispersing to obtain the starch-modified silicon nitride.

[0012] As a covalently bonded ceramic, silicon nitride has a low diffusion coefficient and poor wetting performance with metal ions. By using starch to modify silicon nitride, it is beneficial to promote the combination of silicon nitride with other raw materials, further enhance the room-temperature flexural bond strength of magnesia-carbon brick mud, and also enhance the high-temperature wetting performance of silicon nitride, promote the combination ability of silicon nitride and magnesium-aluminum metal ions, and further improve the high-temperature flexural bond strength and thermal shock resistance of magnesia-carbon brick mud.

[0013] As a further technical solution, during gelatinization, the temperature is 80 - 90 °C and the time is 10 - 20 min.

[0014] As a further technical solution, the mass ratio of the starch to the silicon nitride is 1:19 - 1:9.

[0015] When the mass ratio of the starch to the silicon nitride is 1:19 - 1:9, it can further improve the room-temperature and high-temperature flexural bond strength and thermal shock resistance of magnesia-carbon brick mud.

[0016] As a further technical solution, the particle sizes of the magnesite, cordierite powder, kaolin, and silicon nitride are each independently 80 - 400 mesh.

[0017] As a further technical solution, the particle size of the magnesite is 80 - 100 mesh; and / or

[0018] the particle size of the cordierite powder is 120 - 140 mesh; and / or

[0019] the particle size of the kaolin is 270 - 325 mesh; and / or

[0020] the particle size of the silicon nitride is 325 - 400 mesh.

[0021] As a further technical solution, the raw materials further include 0.5 - 1 part by weight of an antifoaming agent, and the antifoaming agent is an organosilicon antifoaming agent.

[0022] The addition of the antifoaming agent can effectively reduce the porosity of the magnesia-carbon brick mud, improve the density of the magnesia-carbon brick mud, and contribute to improving the room-temperature flexural bond strength of the magnesia-carbon brick mud.

[0023] The present invention also provides a method for preparing the magnesia-carbon brick mud for a ladle, including the following steps: mixing the raw materials evenly and adding water to mix until uniform to obtain the magnesia-carbon brick mud.

[0024] As a further technical solution, the mass ratio of the raw materials to water is 95:5 - 98:2.

[0025] The working principle and beneficial effects of the present invention are as follows:

[0026] 1. In the present invention, a mixture of pseudo-boehmite and magnesium aluminum silicate is used as the binder for the magnesia-carbon brick paste. On the one hand, through the synergistic effect of the two, the bonding ability of the magnesia-carbon brick paste is significantly improved, and the room-temperature flexural bonding strength of the magnesia-carbon brick paste is enhanced. On the other hand, magnesium aluminum silicate can adsorb the water vapor decomposed from pseudo-boehmite at high temperatures, reduce the porosity in the magnesia-carbon brick paste, and prevent the occurrence of hydration reactions, thereby improving the high-temperature flexural bonding strength and thermal shock resistance of the magnesia-carbon brick paste.

[0027] 2. In the present invention, by using starch to modify silicon nitride, it is beneficial to promote the combination of silicon nitride with other raw materials, further enhancing the room-temperature flexural bonding strength of the magnesia-carbon brick paste, and it can also enhance the high-temperature wetting performance of silicon nitride, promote the combination ability of silicon nitride and magnesium-aluminum metal ions, and further improve the high-temperature flexural bonding strength and thermal shock resistance of the magnesia-carbon brick paste. Specific embodiments

[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention.

[0029] In the following examples and comparative examples, unless otherwise specified, the magnesia is purchased from Yingkou Renxing Magnesium Industry Co., Ltd., with a particle size of 100 mesh, and the mass fraction of magnesium oxide in the magnesia ≥ 97.5%; the cordierite powder is purchased from Huaihua Ancheng Refractory Materials Co., Ltd., with a particle size of 140 mesh, and the mass fraction of silicon dioxide in the cordierite powder ≥ 49%; the kaolin is purchased from Pengyu Building Materials Factory, Lingshou County, with a particle size of 325 mesh; the silicon nitride is purchased from Ruijiang Metal Materials Co., Ltd., Qinghe County, with a particle size of 400 mesh; the pseudo-boehmite is purchased from Shandong Yulong New Materials Co., Ltd., with the product number YL-0016; the magnesium aluminum silicate is purchased from Jiangsu Bost Chemical Technology Co., Ltd.; the starch is sweet potato starch; the silicone defoamer is purchased from Sichuan Shangqing Xinrui Environmental Protection Technology Co., Ltd., with the model SQXCL001.

[0030] Example 1

[0031] A preparation method of a ladle magnesia-carbon brick paste, comprising the following steps: by weight, 30 parts of magnesia, 20 parts of cordierite powder, 10 parts of kaolin, 5 parts of silicon nitride, 2 parts of pseudo-boehmite, and 3 parts of magnesium aluminum silicate are mixed evenly, and 3.5 parts of water are added and mixed to uniformity to obtain the magnesia-carbon brick paste.

[0032] Example 2

[0033] A preparation method of ladle magnesia-carbon brick ramming mix, comprising the following steps: by weight, 40 parts of magnesite, 30 parts of cordierite powder, 20 parts of kaolin, 10 parts of silicon nitride, 4 parts of pseudoboehmite, and 6 parts of magnesium aluminum silicate are mixed evenly, and 5.5 parts of water are added and mixed until homogeneous to obtain the magnesia-carbon brick ramming mix.

[0034] Example 3

[0035] The difference between this example and Example 2 is only that, in this example, the weight fraction of pseudoboehmite is 9 parts and the weight fraction of magnesium aluminum silicate is 1 part.

[0036] Example 4

[0037] The difference between this example and Example 2 is only that, in this example, the weight fraction of pseudoboehmite is 6 parts and the weight fraction of magnesium aluminum silicate is 4 parts.

[0038] Example 5

[0039] The difference between this example and Example 2 is only that, in this example, the weight fraction of pseudoboehmite is 8 parts and the weight fraction of magnesium aluminum silicate is 2 parts.

[0040] Example 6

[0041] The difference between this example and Example 2 is only that, in this example, the weight fraction of pseudoboehmite is 7 parts and the weight fraction of magnesium aluminum silicate is 3 parts.

[0042] Example 7

[0043] The difference between this example and Example 6 is only that, in this example, the silicon nitride is starch-modified silicon nitride, and the preparation method of the starch-modified silicon nitride is: 0.25 part of starch is dissolved in 1 part of water, mixed evenly, gelatinized at 85 °C for 15 min, then 9.75 parts of silicon nitride are added, dispersed evenly, cooled and dried, and shaken and dispersed to obtain the starch-modified silicon nitride.

[0044] Example 8

[0045] The difference between this example and Example 6 is only that, in this example, the silicon nitride is starch-modified silicon nitride, and the preparation method of the starch-modified silicon nitride is: 2 parts of starch are dissolved in 8 parts of water, mixed evenly, gelatinized at 85 °C for 15 min, then 8 parts of silicon nitride are added, dispersed evenly, cooled and dried, and shaken and dispersed to obtain the starch-modified silicon nitride.

[0046] Example 9

[0047] The difference between this embodiment and Embodiment 6 is only that in this embodiment, the silicon nitride is starch-modified silicon nitride, and the preparation method of the starch-modified silicon nitride is as follows: Dissolve 0.5 part of starch in 2 parts of water, mix evenly, gelatinize at 85°C for 15 min, then add 9.5 parts of silicon nitride, disperse evenly, cool and dry, and shake and disperse to obtain starch-modified silicon nitride.

[0048] Example 10

[0049] The difference between this embodiment and Embodiment 10 is only that in this embodiment, the raw materials further include 1 part of organosilicon defoamer.

[0050] Example 11

[0051] The difference between this embodiment and Embodiment 10 is only that in this embodiment, the raw materials further include 1 part of organosilicon defoamer.

[0052] Comparative Example 1

[0053] The difference between this comparative example and Embodiment 1 is only that in this comparative example, magnesium aluminum silicate is not added, and the weight fraction of added pseudo-boehmite is 5 parts.

[0054] Comparative Example 2

[0055] The difference between this comparative example and Embodiment 1 is only that in this comparative example, pseudo-boehmite is not added, and the weight fraction of added magnesium aluminum silicate is 5 parts.

[0056] Comparative Example 3

[0057] The difference between this comparative example and Embodiment 1 is only that in this comparative example, neither pseudo-boehmite nor magnesium aluminum silicate is added.

[0058] The following performance tests were carried out on the magnesia-carbon brick mud prepared in Examples 1-11 and Comparative Examples 1-3:

[0059] ① Room temperature flexural bond strength: The room temperature flexural bond strength of the magnesia-carbon brick mud was tested in accordance with GB / T 22459.4-2022 "Refractory Mortar - Part 4: Test Method for Room Temperature Flexural Bonding Strength", wherein the consistency of the magnesia-carbon brick mud was adjusted to 15% by the vibrating table method, and the drying temperature was 110°C and the time was 24 h;

[0060] ②High-temperature flexural bond strength: The high-temperature flexural bond strength of the magnesia-carbon brick mortar was tested in accordance with GB / T 22459.7-2019 "Refractory mortar - Part 7: Test methods for other properties". Among them, the consistency of the magnesia-carbon brick mortar was adjusted to 15% by the vibrating table method. The drying temperature was 110 °C and the time was 24 h, and the high-temperature sintering temperature was 1300 °C and the time was 3 h;

[0061] ③Number of thermal shock cycles: The number of thermal shock cycles of the magnesia-carbon brick mortar was tested in accordance with Method 3 (air quenching method) in GB / T 30873-2014 "Refractory materials - Test method for thermal shock resistance", where the temperature was 300 °C.

[0062] The test results are shown in Table 1 below.

[0063] Table 1 Performance test results

[0064]

[0065] It can be seen from the data in the table that the magnesia-carbon brick mortar prepared by the present invention has good normal-temperature and high-temperature flexural bond strength and thermal shock resistance, and can meet the production requirements. The comparison between Example 1 and Comparative Examples 1-3 shows that by adding a binder composed of pseudoboehmite and magnesium aluminum silicate, the purpose of synergistic effect can be achieved, and the normal-temperature and high-temperature flexural bond strength and thermal shock resistance of the magnesia-carbon brick mortar are significantly improved.

[0066] The comparison between Examples 2-3 and Examples 4-6 shows that when the mass ratio of pseudoboehmite to magnesium aluminum silicate is 3:2 - 4:1, the normal-temperature and high-temperature flexural bond strength and thermal shock resistance of the magnesia-carbon brick mortar can be further improved, and the best mass ratio is 7:3.

[0067] The comparison between Example 6 and Examples 7-10 shows that by using starch to modify silicon nitride, it is beneficial to further improve the normal-temperature and high-temperature flexural bond strength and thermal shock resistance of the magnesia-carbon brick mortar.

[0068] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A ladle magnesia-carbon brick ramming mass, characterized in that, The raw materials include the following components in parts by weight: 30-40 parts of magnesite, 20-30 parts of cordierite powder, 10-20 parts of kaolin, 5-10 parts of silicon nitride, and 5-10 parts of binder; The binder is composed of pseudoboehmite and magnesium aluminum silicate.

2. The mud for ladle magnesia-carbon bricks according to claim 1, characterized in that, The mass ratio of the pseudoboehmite to the magnesium aluminum silicate is 3:2 - 4:

1.

3. The ramming mass for ladle magnesia-carbon bricks according to claim 2, wherein The mass ratio of the pseudoboehmite to the magnesium aluminum silicate is 7:

3.

4. A ladle magnesia-carbon brick mudding according to claim 1, characterized in that The silicon nitride is starch-modified silicon nitride, and the preparation method of the starch-modified silicon nitride is as follows: dissolve starch in water, mix evenly, gelatinize, add silicon nitride, disperse evenly, cool and dry, and shake and disperse to obtain the starch-modified silicon nitride.

5. The mud for ladle magnesia-carbon bricks according to claim 4, characterized in that The mass ratio of the starch to the silicon nitride is 1:19 - 1:

9.

6. A ladle magnesia-carbon brick ramming mass according to claim 1, characterized in that, The particle sizes of the magnesite, cordierite powder, kaolin, and silicon nitride are each independently 80-400 mesh.

7. The gunning mix for ladle magnesia-carbon bricks according to claim 6, characterized in that, The particle size of the magnesite is 80-100 mesh; and / or The particle size of the cordierite powder is 120-140 mesh; and / or The particle size of the kaolin is 270-325 mesh; and / or The particle size of the silicon nitride is 325-400 mesh.

8. A ladle magnesia-carbon brick ramming mass according to claim 1, wherein, The raw materials further include 0.5-1 part by weight of an antifoaming agent, and the antifoaming agent is an organosilicon antifoaming agent.

9. A preparation method of the ramming mass for ladle magnesia-carbon bricks according to any one of claims 1-8, characterized in that, It includes the following steps: mix the raw materials evenly, add water and mix until uniform to obtain the magnesia-carbon brick mud.

10. A method for preparing the mud for ladle magnesia-carbon bricks according to claim 9, characterized in that, The mass ratio of the raw materials to water is 95:5 - 98:2.

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