Clay brick with high alkali corrosion resistance and preparation method thereof

Abstract

The present application discloses a clay brick with high alkali corrosion resistance and a preparation method thereof. The raw materials of the clay brick include the following components by weight percentage: 50% to 70% clay clinker, 20% to 40% bauxite clinker, 5% to 15% white mud, and 5% to 10% phosphoric acid. The preparation method comprises: weighing the clay clinker, bauxite clinker, and white mud according to their weight percentages, dry-mixing, adding a portion of phosphoric acid, and wet-mixing to obtain a clay material; trapping the clay material, adding the remaining phosphoric acid, wet-mixing again, and pressing the clay material with a brick press to obtain a brick blank; drying the brick blank, firing it in a kiln, removing it after firing and immersing it in a phosphoric acid tank to obtain a clay brick impregnated with phosphoric acid; and heat-treating the clay brick impregnated with phosphoric acid to obtain a clay brick. This preparation method does not require vacuuming when immersing the brick blank in phosphoric acid, and the heat treatment temperature of the clay brick impregnated with phosphoric acid in the kiln does not need to be too high. The requirements for equipment and production conditions are low, and the alkali corrosion resistance of the clay brick is improved.

Description

Technical Field

[0001] The present application relates to the technical field of refractory materials, and in particular to a clay brick with high alkali corrosion resistance and a preparation method thereof. Background Art

[0002] Phosphoric acid-impregnated clay bricks used as blast furnace cooling stave linings are required to exhibit excellent alkali corrosion resistance, high strength, and low porosity, significantly exceeding the performance requirements of ordinary clay bricks. Phosphoric acid-impregnated clay bricks, as refractory bricks, primarily serve to resist corrosion from alkali metals and other substances in the blast furnace. Phosphoric acid impregnation is primarily intended to reduce surface pores and the apparent porosity of the product, resulting in a denser structure and, therefore, less alkali metal corrosion.

[0003] The traditional production process for phosphate-impregnated clay bricks involves taking ordinary, dense clay bricks that have been dried and fired at high temperatures, vacuum-immersing them in industrial phosphoric acid for a specified period of time, removing them to dry, and then subjecting them to a heat treatment at temperatures exceeding 600°C. This process is complex and requires high equipment and temperatures. During the heat treatment, the phosphates containing crystal water dehydrate to form water vapor, which reduces the density of the clay bricks, accelerates damage to pores and surrounding areas, and shortens the clay bricks' service life. Summary of the Invention

[0004] The present invention provides a clay brick with high alkali corrosion resistance and a preparation method thereof, so as to solve the technical problems in the prior art of phosphate impregnated clay bricks, such as complicated production process and high requirements on equipment and temperature.

[0005] To achieve the above object, the technical solution provided by the present invention is as follows:

[0006] The first aspect of the present invention provides a clay brick with high alkali corrosion resistance, the raw materials of which include the following components in percentage by weight: 50% to 70% clay clinker, 20% to 40% bauxite clinker, 5% to 15% white mud, and 5% to 10% phosphoric acid.

[0007] Furthermore, the Al2O3 content in the bauxite clinker is greater than or equal to 80%, the sum of the CaO and MgO contents is less than or equal to 0.8%, and the Fe2O3 content is less than or equal to 2.0%.

[0008] Furthermore, the particle size of the clay clinker is 0<particle size≤5mm.

[0009] Furthermore, the phosphoric acid is industrial phosphoric acid, wherein the phosphoric acid concentration is greater than or equal to 85% and the specific gravity is greater than or equal to 1.55.

[0010] The second aspect of the present invention provides a method for preparing the above-mentioned clay brick with high alkali corrosion resistance, comprising the following steps:

[0011] S1. Weigh the clay clinker, the bauxite clinker, and the white mud according to their weight percentages, dry-mix them, add part of the phosphoric acid, and wet-mix them to obtain a mud material;

[0012] S2, mixing the clay obtained in step S1, then adding the remaining phosphoric acid, wet mixing again, and pressing with a brick press to obtain a brick;

[0013] S3, drying the bricks obtained in step S2, firing them in a kiln, taking them out after firing and immersing them in a phosphoric acid tank to obtain clay bricks impregnated with phosphoric acid;

[0014] S4. Heat-treating the clay bricks soaked in phosphoric acid in step S3 to obtain the clay bricks.

[0015] Furthermore, the amount of the phosphoric acid used in step S1 is 75% to 85% of the total amount of the phosphoric acid in the raw material.

[0016] Furthermore, the step of heat treatment in the kiln in step S4 includes: increasing the temperature in the kiln to 400° C. at a rate of 50° C. / h, and keeping the temperature at 400° C. for 4 hours.

[0017] Furthermore, in step S3, the firing temperature in the kiln is 1250° C. to 1300° C., and the firing time is 7 hours to 12 hours.

[0018] Furthermore, the phosphoric acid tank is filled with industrial phosphoric acid, and the fired bricks are immersed in the phosphoric acid tank for 1 hour to 4 hours.

[0019] The clay bricks with high alkali corrosion resistance provided by the present invention use phosphoric acid as one of the raw materials, that is, phosphoric acid is added as a binder during the production process of the clay bricks, so that the clay bricks have better alkali corrosion resistance. The preparation method of the clay bricks provided by the present invention first mixes part of the phosphoric acid with other raw materials, and the phosphoric acid is coated on the outside of the particles. After the materials are trapped, the remaining phosphoric acid is added again for wet mixing again, and then pressed into shape, dried, and fired. After the firing is completed, it is immersed in a phosphoric acid pool, taken out and dried to obtain the clay bricks; in the above preparation method, when the fired bricks are immersed in phosphoric acid, there is no need to vacuum, and the temperature of the clay bricks immersed in phosphoric acid in the kiln does not need to be too high, so the requirements for equipment and production conditions are low, the production cost is reduced, and the alkali corrosion resistance of the clay bricks is improved. DETAILED DESCRIPTION

[0020] In order to help those skilled in the art better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without making any creative efforts shall fall within the scope of protection of this application.

[0021] In a first aspect of an embodiment of the present application, a clay brick with high alkali corrosion resistance is provided, wherein the raw materials include the following components in percentage by weight: 50% to 70% clay clinker, 20% to 40% bauxite clinker, 5% to 15% white mud, and 5% to 10% phosphoric acid.

[0022] In the embodiments of the present application, phosphoric acid is added as a binder to the raw materials for preparing clay bricks. The clay bricks prepared by combining phosphoric acid with other raw materials have reduced surface pores, lowered apparent porosity, and made the clay bricks denser, thereby slowing down the corrosion of alkali metals.

[0023] Specifically, the bauxite clinker has an Al2O3 content greater than or equal to 80%, a combined CaO and MgO content less than or equal to 0.8%, and a Fe2O3 content less than or equal to 2.0%. The bauxite clinker is finely powdered, with a particle size of 180 mesh or larger. The clay clinker has a particle size of 0 < particle size ≤ 5 mm. A mixture of clinkers within the aforementioned particle size range can be selected for the clay clinker. The phosphoric acid is industrial phosphoric acid, generally requiring a phosphoric acid content greater than or equal to 85% and a specific gravity greater than or equal to 1.55.

[0024] The second aspect of the embodiment of the present application provides a method for preparing the above-mentioned clay brick with high alkali corrosion resistance, comprising the following steps:

[0025] S1. Weigh clay clinker, high-aluminum clinker and white mud according to their weight percentages, dry-mix them, add part of phosphoric acid, and wet-mix them to obtain mud;

[0026] S2, the mud material prepared in step S1 is mixed, and then the remaining phosphoric acid is added, wet-mixed again, and pressed into shape using a brick press to obtain a brick;

[0027] S3, drying the bricks obtained in step S2, firing them in a kiln, taking them out after firing and immersing them in a phosphoric acid tank to obtain clay bricks impregnated with phosphoric acid;

[0028] S4. Heat-treating the clay impregnated with phosphoric acid in step S3 to obtain clay bricks.

[0029] The method for preparing clay bricks with high alkali corrosion resistance in the embodiment of the present application mainly adds phosphoric acid as a binder during the production process of the clay bricks. First, a part of the phosphoric acid is fully mixed with other raw materials, and the phosphoric acid is coated on the outside of the particles. After the materials are trapped, the remaining phosphoric acid is added again and wet mixed again, and then pressed into shape, dried, and fired. After firing, it is immersed in a phosphoric acid pool, taken out and dried, and heat-treated in a drying kiln to obtain clay bricks; in the above preparation method, when the fired bricks are immersed in phosphoric acid, there is no need to vacuum, and the temperature of the clay bricks immersed in phosphoric acid does not need to be too high when drying in the kiln, so the requirements for equipment and production conditions are low, which reduces production costs and improves the alkali corrosion resistance of the clay bricks. In the embodiment of the present application, the bricks are also placed in phosphoric acid for immersion after firing. The immersion time is 1h to 4h.

[0030] In some embodiments, the amount of phosphoric acid used in step S1 is 75% to 85% of the total amount of phosphoric acid in the raw materials. Adding phosphoric acid to the raw materials for clay bricks in batches and mixing them together can make the phosphoric acid and other raw materials mix more evenly, thereby forming a uniform layer of phosphorus-containing compounds on the surface of some clinker particles.

[0031] In some embodiments, the kiln heat treatment step in step S4 includes increasing the kiln temperature to 400°C at a rate of 50°C / h and maintaining the temperature at 400°C for 4 hours. This indicates that in the present embodiments, the heat treatment temperature of the clay bricks impregnated with phosphoric acid is lower, which relatively reduces production requirements and costs. Furthermore, at low temperatures, the phosphate containing crystalline water does not dehydrate, thereby preventing damage to the pores and their surrounding areas, thereby ensuring the density of the product.

[0032] In order to facilitate the immersion of fired bricks in phosphoric acid, multiple bricks can be stacked on a pallet and packed to make it stable. The whole is immersed in the phosphoric acid pool. The amount of phosphoric acid used should be enough to completely submerge the brick stack. After soaking, pick it up and drain it.

[0033] The clay bricks with high alkali corrosion resistance prepared in the examples of the present application have a phosphorus-containing compound filled between the particles. The applicant believes that this compound is (0.41P2O5·0.59Al2O3)·2.6SiO2. This compound has a dense structure and is mostly network-bound between the clinker particles, which significantly reduces the surface porosity and expansion rate. Due to the evolution of the structure, it is not easy to react with alkali metals, which can prevent the corrosion and diffusion of alkali metals, making the clay bricks have excellent alkali resistance. In addition, phosphoric acid is added during the production process, which forms a layer of annular phosphorus-containing compounds on the surface of some clinker particles. The applicant believes that this compound is (0.15P2O5·0.85Al2O3)·2.7SiO2, which can further prevent and slow down the interaction between aluminum silicon clinker and alkali metals, thereby delaying the corrosion of clay bricks by alkali metals.

[0034] All reagents in the following examples are commercially available.

[0035] Example 1

[0036] The weight percentage of each raw material in the high alkali corrosion resistance clay brick is shown in Table 1. The product model of each component is shown in Table 2.

[0037] Table 1 Weight percentage of each raw material component of clay bricks in Examples 1 to 3

[0038] Example 1 Example 2 Example 3 Component name Addition amount Addition amount Addition amount YNS44 clay clinker 3-5mm 10％ 12％ 15％ YNS44 clay clinker 1-3mm 35％ 33％ 33％ YNS44 clay clinker 0-1mm 15％ 15％ 12％ GAL80 bauxite clinker 180 mesh 30％ 32％ 30％ Guangxi white mud 200 mesh 10％ 8％ 10％ Industrial phosphoric acid 6％ 6％ 6％

[0039] Table 2 Product model of each raw material component of clay bricks in Examples 1 to 3

[0040]

[0041] The method for preparing clay bricks with high alkali corrosion resistance in this embodiment includes the following steps:

[0042] 1. Weigh clay clinker, bauxite clinker and white mud (manually batched or automatically batched) according to their weight percentages, add them into a mixer and dry mix them. After dry mixing for 5 minutes, add 80% of the industrial phosphoric acid in the formula and wet mix them. Wet mix for more than 15 minutes, take out the trapped materials for 20 hours to obtain mud.

[0043] 2. Add the mud back into the mixer and add the remaining industrial phosphoric acid in the formula to the mud, wet mix again for 8 minutes, and use a brick press to press it into bricks of the required size.

[0044] 3. After the bricks are naturally dried for more than 12 hours, they are placed in a drying kiln for drying, and then fired in the kiln at a firing temperature of 1300℃ for 10 hours, and then naturally cooled before being taken out of the kiln.

[0045] 4. After leaving the kiln, select the bricks with qualified size and appearance, stack them on pallets, pack them to make them stable, and immerse them as a whole in an industrial phosphoric acid pool. The phosphoric acid needs to completely cover the height of the brick stack. Soak for 2 hours, pick them up and drain them.

[0046] 5. After phosphoric acid impregnation, the brick stacks, along with the pallets, are sent to a drying kiln for heat treatment. The temperature in the kiln is raised to 400°C at a rate of 50°C / hour and maintained for 4 hours, followed by natural cooling. After cooling, the brick stacks are unpacked, sorted, inspected, cleaned, and packaged for storage.

[0047] Example 2

[0048] The weight percentage of each raw material in the high alkali corrosion resistance clay brick is shown in Table 1.

[0049] The product models of each component are shown in Table 2.

[0050] The preparation method of clay bricks is the same as that in Example 1.

[0051] Example 3

[0052] The weight percentage of each raw material in the high alkali corrosion resistance clay brick is shown in Table 1.

[0053] The product models of each component are shown in Table 2.

[0054] The preparation method of clay bricks is the same as that in Example 1.

[0055] The clay bricks prepared in Examples 1 to 3 were tested, and the results are shown in Table 3.

[0056] Table 3 Clay brick test data of Examples 1 to 3

[0057]

[0058]

[0059] From the test results in Table 3, it can be seen that the clay bricks obtained by the preparation methods of Examples 1 to 3 have significantly reduced apparent porosity, significantly improved compressive strength and flexural strength at room temperature, and especially enhanced alkali corrosion resistance.

[0060] The above description of the disclosed embodiments is intended to enable one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be readily apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not limited to the embodiments shown herein but is intended to conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A clay brick with high alkali corrosion resistance, characterized by: The raw materials include the following components in percentage by weight: Clay clinker 50%-70%, bauxite clinker 20%-40%, white mud 5%-15%, phosphoric acid 5%-10%; The method for preparing the clay brick with high alkali corrosion resistance comprises the following steps: S1. Weigh the clay clinker, the bauxite clinker, and the white mud according to their weight percentages, dry-mix them, add part of the phosphoric acid, and wet-mix them to obtain a mud material; S2, mixing the clay obtained in step S1, then adding the remaining phosphoric acid, wet mixing again, and pressing with a brick press to obtain a brick; S3, drying the bricks obtained in step S2, firing them in a kiln, taking them out after firing and immersing them in a phosphoric acid tank to obtain clay bricks impregnated with phosphoric acid; S4. Heat-treating the clay bricks soaked in phosphoric acid in step S3 to obtain the clay bricks.

2. The high alkali corrosion resistance clay brick according to claim 1, characterized in that: The Al2O3 content in the bauxite clinker is greater than or equal to 80%, the sum of the CaO and MgO contents is less than or equal to 0.8%, and the Fe2O3 content is less than or equal to 2.0%.

3. The high alkali corrosion resistance clay brick according to claim 1, characterized in that: The particle size of the clay clinker is 0<particle size≤5mm.

4. The high alkali corrosion resistance clay brick according to claim 1, characterized in that: The phosphoric acid is industrial phosphoric acid.

5. The high alkali corrosion resistance clay brick according to any one of claims 1 to 4, characterized in that: The amount of the phosphoric acid used in step S1 is 75% to 85% of the total amount of the phosphoric acid in the raw material.

6. The high alkali corrosion resistance clay brick according to any one of claims 1 to 4, characterized in that: The step of heat treatment in the kiln in step S4 includes: increasing the temperature in the kiln to 400° C. at a rate of 50° C. / h, and keeping the temperature at 400° C. for 4 hours.

7. The high alkali corrosion resistance clay brick according to any one of claims 1 to 4, characterized in that: The firing temperature in the kiln in step S3 is 1250° C. to 1300° C., and the firing time is 7 hours to 12 hours.

8. The high alkali corrosion resistance clay brick according to any one of claims 1 to 4, characterized in that: The phosphoric acid tank is filled with industrial phosphoric acid, and the fired bricks are immersed in the phosphoric acid tank for 1 hour to 4 hours.

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