Aluminum phosphate wear-resistant brick and its preparation method and application

Abstract

The present invention provides an aluminum phosphate wear-resistant brick and its preparation method and application, belonging to the technical field of refractory materials. N-doped carbon nitride is prepared, mixed with silicon carbide powder, and after surface modification with polydopamine, added to a silica sol, calcined, and added to an aluminum phosphate sol. The product is added to high-alumina bauxite, stirred and mixed evenly, machine-pressed and calcined to produce an aluminum phosphate wear-resistant brick. The aluminum phosphate wear-resistant brick produced by the present invention has good wear resistance, excellent mechanical properties, good forming performance, good refractory and high-temperature resistance, a wide range of raw material sources, low cost, and the resulting product effectively avoids problems such as cracking and falling off, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of refractory materials, and in particular to an aluminum phosphate wear-resistant brick and a preparation method and application thereof. Background Art

[0002] Extending the operating cycle of rotary kilns, tapping the production potential of my country's cement kilns, and improving clinker output and quality are crucial for catching up with world-leading standards and achieving modernization in the cement industry. The quality of a cement kiln's lining directly impacts its operating cycle. With the rapid development of large-scale kilns, this conflict will become even more pronounced. Currently, in addition to the firing zone lining, other areas of the rotary kiln, such as the cooler, kiln mouth, and cooling zone, suffer significant damage due to the constant erosion and abrasion of clinker, as well as the rapid cooling and heating effects of cyclical temperature fluctuations. Therefore, in addition to researching solutions for the firing zone lining, there is also an urgent need to develop a new kiln lining material that is both heat-resistant and wear-resistant to meet the needs of expanding production.

[0003] Phosphate materials have high strength, high refractoriness, high wear resistance, good resistance to sudden temperature changes and chemical stability. The development of aluminum phosphate wear-resistant bricks is expected to meet the current market demand. Summary of the Invention

[0004] The purpose of the present invention is to provide an aluminum phosphate wear-resistant brick and its preparation method and application, which has good wear resistance, excellent mechanical properties, good forming performance, good fire resistance and high temperature resistance, a wide source of raw materials, and low cost. The prepared product effectively avoids problems such as cracking and falling off, and has broad application prospects.

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

[0006] The invention provides a preparation method of aluminum phosphate wear-resistant bricks. The method comprises the following steps: preparing N-doped carbon nitride, mixing the mixture with silicon carbide powder, modifying the surface of the mixture with polydopamine, adding the mixture to a silicon dioxide sol, calcining the mixture, adding the mixture to an aluminum phosphate sol, adding the mixture to high-alumina bauxite, stirring and mixing the mixture uniformly, forming the mixture by machine pressing, and calcining the mixture to obtain the aluminum phosphate wear-resistant bricks.

[0007] As a further improvement of the present invention, the following steps are included:

[0008] S1. Preparation of N-doped carbon nitride: urea and citric acid were mixed uniformly, heated and calcined, cooled to room temperature, and crushed to obtain N-doped carbon nitride;

[0009] S2. Preparation of modified ceramic powder: The N-doped carbon nitride and silicon carbide powder obtained in step S1 were added to water, dopamine hydrochloride and a catalyst were added, the reaction was heated with stirring, centrifuged, washed, and dried to obtain a modified ceramic powder;

[0010] S3. Preparation of N-doped carbon nitride / silicon carbide / silicon dioxide powder: dissolving alkyl orthosilicate in ethanol, adding the modified ceramic powder obtained in step S2, stirring and mixing uniformly, adding aqueous hydrochloric acid solution dropwise, stirring and reacting, aging, drying, calcining, and ball milling to obtain N-doped carbon nitride / silicon carbide / silicon dioxide powder;

[0011] S4. Preparation of a wear-resistant binder: Phosphoric acid and aluminum hydroxide were added to water, stirred and mixed, and the N- doped carbon nitride / silicon carbide / silicon dioxide powder obtained in step S3 was added, and the reaction was stirred to obtain a wear-resistant binder;

[0012] S5. Preparation of aluminum phosphate wear-resistant bricks: ball-mill high-alumina bauxite, sieve the fine high-alumina bauxite, add the wear-resistant binder in step S4, stir and mix evenly, press and shape, and calcine to obtain aluminum phosphate wear-resistant bricks.

[0013] As a further improvement of the present invention, the mass ratio of urea to citric acid in step S1 is 10-15:1-2, the heating rate of the heating calcination is 2-3°C / min, the temperature is raised to 500-600°C, and the calcination time is 4-6h.

[0014] As a further improvement of the present invention, the mass ratio of the N-doped carbon nitride, silicon carbide powder, dopamine hydrochloride and catalyst in step S2 is 10-12:7-10:17-22:1-2, the catalyst is a Tris-HCl solution with a pH of 8.5-9, the temperature of the heating and stirring reaction is 40-50°C, and the time is 2-4h.

[0015] As a further improvement of the present invention, the alkyl orthosilicate in step S3 is methyl orthosilicate or ethyl orthosilicate, the mass ratio of the alkyl orthosilicate, modified ceramic powder, ethanol, and hydrochloric acid aqueous solution is 10-15:4-6:120-150:20-25, the concentration of the hydrochloric acid aqueous solution is 1-2 mol / L, the stirring reaction temperature is 35-45°C, the time is 3-5h, the aging time is 5-7h, the calcination temperature is 500-700°C, the time is 1-3h, and the ball milling time is 1-2h.

[0016] As a further improvement of the present invention, the mass ratio of the phosphoric acid, aluminum hydroxide, N-doped carbon nitride / silicon carbide / silicon dioxide powder and water in step S4 is 55-65:11-13:7-10:25-35, the stirring reaction temperature is 40-50°C, and the time is 20-40 minutes.

[0017] As a further improvement of the present invention, the ball milling time in step S5 is 2-4 hours, the mesh size of the sieve is 500 mesh, the mass ratio of the fine high-alumina bauxite and the wear-resistant binder is 10:27-35, the stirring and mixing time is 30-50 minutes, the pressure of the machine pressing is 100-110 MPa, the time is 15-25 minutes, and the calcination temperature is 450-550°C, and the time is 1-3 hours.

[0018] As a further improvement of the present invention, the present invention specifically comprises the following steps:

[0019] S1. Preparation of N-doped carbon nitride: 10-15 parts by weight of urea and 1-2 parts by weight of citric acid were uniformly mixed, heated and calcined at a heating rate of 2-3°C / min to a temperature of 500-600°C for 4-6 hours, cooled to room temperature, and crushed to obtain N-doped carbon nitride;

[0020] S2. Preparation of modified ceramic powder: 10-12 parts by weight of N-doped carbon nitride obtained in step S1 and 7-10 parts by weight of silicon carbide powder were added to 200 parts by weight of water, 17-22 parts by weight of dopamine hydrochloride and 1-2 parts by weight of a catalyst were added, heated to 40-50 ° C, stirred for 2-4h, centrifuged, washed, and dried to obtain a modified ceramic powder;

[0021] The catalyst is a Tris-HCl solution with a pH of 8.5-9;

[0022] S3. Preparation of N-doped carbon nitride / silicon carbide / silicon dioxide powder: Dissolve 10-15 parts by weight of alkyl orthosilicate in 120-150 parts by weight of ethanol, add 4-6 parts by weight of the modified ceramic powder obtained in step S2, stir and mix uniformly, add 20-25 parts by weight of a 1-2 mol / L hydrochloric acid aqueous solution dropwise, stir and react at 35-45°C for 3-5 hours, age for 5-7 hours, dry, calcined at 500-700°C for 1-3 hours, and ball milled for 1-2 hours to obtain N-doped carbon nitride / silicon carbide / silicon dioxide powder;

[0023] S4. Preparation of a wear-resistant binder: 55-65 parts by weight of phosphoric acid and 11-13 parts by weight of aluminum hydroxide were added to 25-35 parts by weight of water, stirred and mixed, and 7-10 parts by weight of the N- doped carbon nitride / silicon carbide / silicon dioxide powder obtained in step S3 was added, and the reaction was stirred at 40-50 ° C for 20-40min to obtain a wear-resistant binder;

[0024] S5. Preparation of aluminum phosphate wear-resistant bricks: ball mill high-alumina bauxite for 2-4 hours, pass through a 500-mesh sieve, and add the wear-resistant binder in step S4 to 10 parts by weight of the fine high-alumina bauxite. Stir and mix for 30-50 minutes, press at 100-110 MPa for 15-25 minutes, and calcinate at 450-550°C for 1-3 hours to produce aluminum phosphate wear-resistant bricks.

[0025] The present invention further protects an aluminum phosphate wear-resistant brick prepared by the above preparation method.

[0026] The present invention further protects the use of the above-mentioned aluminum phosphate wear-resistant brick in the preparation of rotary kiln lining bricks.

[0027] The present invention has the following beneficial effects:

[0028] Carbon nitride refers to a covalent compound with a hardness similar to that of diamond. Its hardness and mechanical properties can be further improved by N doping. The surface is modified with polydopamine to increase its surface active groups such as hydroxyl, amino, and carboxyl, which helps silicon carbide to adhere and be fully distributed in the silica sol. After calcination, N-doped carbon nitride / silicon carbide / silicon dioxide powder is obtained. When added to aluminum phosphate sol, the wear-resistant binder prepared can not only significantly improve the mechanical properties, wear resistance, fire resistance and high temperature resistance of aluminum phosphate wear-resistant bricks, but also effectively solve the problems of hydrogen release caused by the reaction of phosphoric acid or aluminum phosphate solution with a small amount of iron in bauxite aggregate, expansion and cracking of products, and quality degradation by filling gaps.

[0029] The particle size of high-alumina bauxite has a great influence on the forming performance, moisture porosity, bulk density, compressive strength, etc. of the finished product. Finer particle size can significantly improve the forming performance, avoid the problems of easy falling off of the edges and corners of the brick, poor density, and reduced strength. The present invention adopts the ball milling method to obtain high-alumina bauxite with smaller particle size, which can significantly improve the forming performance of aluminum phosphate wear-resistant bricks and improve the mechanical strength and compactness.

[0030] The aluminum phosphate wear-resistant bricks prepared by the present invention have good wear resistance, good mechanical properties, good forming performance, good fire resistance and high temperature resistance, a wide source of raw materials, and low cost. The prepared products effectively avoid problems such as cracking and falling off, and have broad application prospects. DETAILED DESCRIPTION

[0031] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0032] High-alumina bauxite, 0-3 mm, with an aluminum content of 60-80 wt%, was purchased from Zhengzhou Kanghui Refractory Co., Ltd. Silicon carbide powder, with an average particle size of 0.5 μm, was purchased from Shandong Huaen New Materials Technology Co., Ltd.

[0033] Example 1

[0034] This embodiment provides a method for preparing aluminum phosphate wear-resistant bricks, which specifically includes the following steps:

[0035] S1. Preparation of N-doped carbon nitride: 10 parts by weight of urea and 1 part by weight of citric acid were stirred and mixed for 10 minutes, heated and calcined at a heating rate of 2°C / min to 500°C for 4 hours, cooled to room temperature, and crushed to obtain N-doped carbon nitride;

[0036] S2. Preparation of modified ceramic powder: 10 parts by weight of N-doped carbon nitride obtained in step S1 and 7 parts by weight of silicon carbide powder were added to 200 parts by weight of water, 17 parts by weight of dopamine hydrochloride and 1 part by weight of catalyst were added, heated to 40 ° C, stirred for 2h, centrifuged, washed, and dried to obtain a modified ceramic powder;

[0037] The catalyst is a Tris-HCl solution with a pH of 8.5;

[0038] S3. Preparation of N-doped carbon nitride / silicon carbide / silicon dioxide powder: 10 parts by weight of methyl orthosilicate was dissolved in 120 parts by weight of ethanol, 4 parts by weight of the modified ceramic powder obtained in step S2 was added, and the mixture was stirred for 20 minutes. 20 parts by weight of a 1 mol / L hydrochloric acid aqueous solution was added dropwise, and the mixture was stirred at 35°C for 3 hours, aged for 5 hours, dried, calcined at 500°C for 1 hour, and ball-milled for 1 hour to obtain N-doped carbon nitride / silicon carbide / silicon dioxide powder;

[0039] S4. Preparation of a wear-resistant binder: 55 parts by weight of 85wt% phosphoric acid and 11 parts by weight of aluminum hydroxide were added to 25 parts by weight of water, stirred and mixed for 15min, and 7 parts by weight of the N- doped carbon nitride / silicon carbide / silicon dioxide powder obtained in step S3 was added, and the reaction was stirred at 40 ° C for 20min to obtain a wear-resistant binder;

[0040] S5. Preparation of aluminum phosphate wear-resistant bricks: ball-mill high-alumina bauxite for 2 hours, pass through a 500-mesh sieve, and add the wear-resistant binder in step S4 to 10 parts by weight of the fine high-alumina bauxite. Stir and mix for 30 minutes, press at 100 MPa for 15 minutes, and calcinate at 450°C for 1 hour to obtain aluminum phosphate wear-resistant bricks.

[0041] Example 2

[0042] This embodiment provides a method for preparing aluminum phosphate wear-resistant bricks, which specifically includes the following steps:

[0043] S1. Preparation of N-doped carbon nitride: 15 parts by weight of urea and 2 parts by weight of citric acid were stirred and mixed for 10 minutes, heated and calcined at a heating rate of 3°C / min to 600°C for 6 hours, cooled to room temperature, and crushed to obtain N-doped carbon nitride;

[0044] S2. Preparation of modified ceramic powder: 12 parts by weight of N-doped carbon nitride obtained in step S1 and 10 parts by weight of silicon carbide powder were added to 200 parts by weight of water, 22 parts by weight of dopamine hydrochloride and 2 parts by weight of catalyst were added, heated to 50 ° C, stirred for 4h, centrifuged, washed, and dried to obtain a modified ceramic powder;

[0045] The catalyst is a Tris-HCl solution with a pH of 9;

[0046] S3. Preparation of N-doped carbon nitride / silicon carbide / silicon dioxide powder: 15 parts by weight of tetraethyl orthosilicate was dissolved in 150 parts by weight of ethanol, 6 parts by weight of the modified ceramic powder obtained in step S2 was added, and the mixture was stirred for 20 minutes. 25 parts by weight of a 2 mol / L aqueous hydrochloric acid solution was added dropwise, and the mixture was stirred at 45°C for 5 hours, aged for 7 hours, dried, calcined at 700°C for 3 hours, and ball-milled for 2 hours to obtain N-doped carbon nitride / silicon carbide / silicon dioxide powder;

[0047] S4. Preparation of a wear-resistant binder: 65 parts by weight of 85wt% phosphoric acid and 13 parts by weight of aluminum hydroxide were added to 35 parts by weight of water, stirred and mixed for 15min, and 10 parts by weight of the N- doped carbon nitride / silicon carbide / silicon dioxide powder obtained in step S3 was added, and the reaction was stirred at 50 ° C for 40min to obtain a wear-resistant binder;

[0048] S5. Preparation of aluminum phosphate wear-resistant bricks: ball-mill high-alumina bauxite for 4 hours, pass through a 500-mesh sieve, and add the wear-resistant binder in step S4 to 10 parts by weight of the fine high-alumina bauxite. Stir and mix for 50 minutes, press at 110 MPa for 25 minutes, and calcined at 550°C for 3 hours to obtain aluminum phosphate wear-resistant bricks.

[0049] Example 3

[0050] This embodiment provides a method for preparing aluminum phosphate wear-resistant bricks, which specifically includes the following steps:

[0051] S1. Preparation of N-doped carbon nitride: 12 parts by weight of urea and 1.5 parts by weight of citric acid were stirred and mixed for 10 minutes, heated and calcined at a heating rate of 2.5°C / min to 550°C for 5 hours, cooled to room temperature, and crushed to obtain N-doped carbon nitride;

[0052] S2. Preparation of modified ceramic powder: 11 parts by weight of N-doped carbon nitride obtained in step S1 and 8.5 parts by weight of silicon carbide powder were added to 200 parts by weight of water, 20 parts by weight of dopamine hydrochloride and 1.5 parts by weight of catalyst were added, heated to 45 ° C, stirred for 3h, centrifuged, washed, and dried to obtain a modified ceramic powder;

[0053] The catalyst is a Tris-HCl solution with a pH of 8.7;

[0054] S3. Preparation of N-doped carbon nitride / silicon carbide / silicon dioxide powder: 12 parts by weight of tetraethyl orthosilicate was dissolved in 135 parts by weight of ethanol, 5 parts by weight of the modified ceramic powder obtained in step S2 was added, and the mixture was stirred for 20 minutes. 22 parts by weight of a 1.5 mol / L aqueous hydrochloric acid solution was added dropwise, and the mixture was stirred at 40°C for 4 hours, aged for 6 hours, dried, calcined at 600°C for 2 hours, and ball-milled for 1.5 hours to obtain N-doped carbon nitride / silicon carbide / silicon dioxide powder;

[0055] S4. Preparation of a wear-resistant binder: 60 parts by weight of 85wt% phosphoric acid and 12 parts by weight of aluminum hydroxide were added to 30 parts by weight of water, stirred and mixed for 15min, and 8.5 parts by weight of the N- doped carbon nitride / silicon carbide / silica powder obtained in step S3 was added, and the reaction was stirred at 45 ° C for 30min to obtain a wear-resistant binder;

[0056] S5. Preparation of aluminum phosphate wear-resistant bricks: ball-mill high-alumina bauxite for 3 hours, pass through a 500-mesh sieve, and add the wear-resistant binder in step S4 to 10 parts by weight of the fine high-alumina bauxite. Stir and mix for 40 minutes, press at 105 MPa for 20 minutes, and calcinate at 500°C for 2 hours to obtain aluminum phosphate wear-resistant bricks.

[0057] Comparative Example 1

[0058] Compared with Example 3, the difference is that citric acid is not added in step S1.

[0059] The details are as follows:

[0060] S1. Preparation of carbon nitride: 12 parts by weight of urea were heated and calcined at a heating rate of 2.5°C / min to 550°C for 5 hours, cooled to room temperature, and crushed to obtain carbon nitride.

[0061] Comparative Example 2

[0062] Compared with Example 3, the difference is that silicon carbide is not added in step S2.

[0063] The details are as follows:

[0064] S2. Preparation of modified ceramic powder: 19.5 parts by weight of N-doped carbon nitride obtained in step S1 was added to 200 parts by weight of water, 20 parts by weight of dopamine hydrochloride and 1.5 parts by weight of catalyst were added, heated to 45 ° C, stirred for 3h, centrifuged, washed, and dried to obtain a modified ceramic powder;

[0065] The catalyst is a Tris-HCl solution with a pH of 8.7.

[0066] Comparative Example 3

[0067] Compared with Example 3, the difference is that no polydopamine modification is performed in step S2.

[0068] The details are as follows:

[0069] S2. Preparation of ceramic powder: 11 parts by weight of the N-doped carbon nitride obtained in step S1 and 8.5 parts by weight of silicon carbide powder were uniformly mixed to obtain ceramic powder.

[0070] Comparative Example 4

[0071] Compared with embodiment 3, the difference is that step S2 is not performed.

[0072] The details are as follows:

[0073] S1. Preparation of N-doped carbon nitride: 12 parts by weight of urea and 1.5 parts by weight of citric acid were stirred and mixed for 10 minutes, heated and calcined at a heating rate of 2.5°C / min to 550°C for 5 hours, cooled to room temperature, and crushed to obtain N-doped carbon nitride;

[0074] S2. Preparation of N-doped carbon nitride / silicon dioxide powder: 12 parts by weight of tetraethyl orthosilicate was dissolved in 135 parts by weight of ethanol, 5 parts by weight of the N-doped carbon nitride prepared in step S1 was added, and the mixture was stirred for 20 minutes. 22 parts by weight of a 1.5 mol / L aqueous hydrochloric acid solution was added dropwise, and the mixture was stirred at 40°C for 4 hours, aged for 6 hours, dried, calcined at 600°C for 2 hours, and ball-milled for 1.5 hours to obtain N-doped carbon nitride / silicon dioxide powder;

[0075] S3. Preparation of a wear-resistant binder: 60 parts by weight of 85wt% phosphoric acid and 12 parts by weight of aluminum hydroxide were added to 30 parts by weight of water, stirred and mixed for 15min, and 8.5 parts by weight of the N- doped carbon nitride / silica powder obtained in step S2 was added, and the reaction was stirred at 45 ° C for 30min to obtain a wear-resistant binder;

[0076] S4. Preparation of aluminum phosphate wear-resistant bricks: ball-mill high-alumina bauxite for 3 hours, pass through a 500-mesh sieve, and add the wear-resistant binder in step S3 to 10 parts by weight of the fine high-alumina bauxite. Stir and mix for 40 minutes, press at 105 MPa for 20 minutes, and calcinate at 500°C for 2 hours to obtain aluminum phosphate wear-resistant bricks.

[0077] Comparative Example 5

[0078] Compared with embodiment 3, the difference is that step S3 is not performed.

[0079] The details are as follows:

[0080] S1. Preparation of N-doped carbon nitride: 12 parts by weight of urea and 1.5 parts by weight of citric acid were stirred and mixed for 10 minutes, heated and calcined at a heating rate of 2.5°C / min to 550°C for 5 hours, cooled to room temperature, and crushed to obtain N-doped carbon nitride;

[0081] S2. Preparation of modified ceramic powder: 11 parts by weight of N-doped carbon nitride obtained in step S1 and 8.5 parts by weight of silicon carbide powder were added to 200 parts by weight of water, 20 parts by weight of dopamine hydrochloride and 1.5 parts by weight of catalyst were added, heated to 45 ° C, stirred for 3h, centrifuged, washed, and dried to obtain a modified ceramic powder;

[0082] The catalyst is a Tris-HCl solution with a pH of 8.7;

[0083] S3. Preparation of a wear-resistant binder: 60 parts by weight of 85wt% phosphoric acid and 12 parts by weight of aluminum hydroxide were added to 30 parts by weight of water, stirred and mixed for 15min, 8.5 parts by weight of the modified ceramic powder obtained in step S2 was added, the reaction was stirred at 45 ° C for 30min to obtain a wear-resistant binder;

[0084] S4. Preparation of aluminum phosphate wear-resistant bricks: ball-mill high-alumina bauxite for 3 hours, pass through a 500-mesh sieve, and add the wear-resistant binder in step S3 to 10 parts by weight of the fine high-alumina bauxite. Stir and mix for 40 minutes, press at 105 MPa for 20 minutes, and calcinate at 500°C for 2 hours to obtain aluminum phosphate wear-resistant bricks.

[0085] Comparative Example 6

[0086] Compared with Example 3, the difference is that no N-doped carbon nitride / silicon carbide / silicon dioxide powder is added in step S4.

[0087] The details are as follows:

[0088] S4. Preparation of wear-resistant binder: 60 parts by weight of 85wt% phosphoric acid and 12 parts by weight of aluminum hydroxide were added to 30 parts by weight of water, stirred and mixed for 15 minutes, and stirred and reacted at 45°C for 30 minutes to obtain a wear-resistant binder.

[0089] Comparative Example 7

[0090] Compared with Example 3, the difference is that in step S5, the high-alumina bauxite is not ball-milled and sieved.

[0091] The details are as follows:

[0092] S5. Preparation of aluminum phosphate wear-resistant bricks: Add the wear-resistant binder in step S4 to 10 parts by weight of high-alumina bauxite, stir and mix for 40 minutes, press at 105 MPa for 20 minutes, and calcined at 500°C for 2 hours to obtain aluminum phosphate wear-resistant bricks.

[0093] Test Example 1

[0094] The aluminum phosphate wear-resistant bricks prepared in Examples 1-3 and Comparative Examples 1-7 were heated at 700° C. for 1 hour and then cooled to room temperature. Their properties were tested. The results are shown in Table 1.

[0095] Table 1

[0096]

[0097] It can be seen from the above table that the aluminum phosphate wear-resistant bricks prepared in Examples 1-3 of the present invention have better comprehensive performance.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing aluminum phosphate wear-resistant bricks, characterized in that: The following steps are involved: S1. Preparation of N-doped carbon nitride: urea and citric acid were mixed uniformly, heated and calcined, cooled to room temperature, and crushed to obtain N-doped carbon nitride; the mass ratio of urea to citric acid was 10-15:1-2; S2. Preparation of modified ceramic powder: The N-doped carbon nitride and silicon carbide powder obtained in step S1 were added to water, dopamine hydrochloride and a catalyst were added, the reaction was heated with stirring, centrifuged, washed, and dried to obtain a modified ceramic powder; the mass ratio of the N-doped carbon nitride, silicon carbide powder, dopamine hydrochloride and catalyst was 10-12:7-10:17-22:1-2; S3. Preparation of N-doped carbon nitride / silicon carbide / silicon dioxide powder: dissolving an alkyl orthosilicate in ethanol, adding the modified ceramic powder obtained in step S2, stirring and mixing uniformly, adding a hydrochloric acid aqueous solution dropwise, stirring and reacting, aging, drying, calcining, and ball milling to obtain an N-doped carbon nitride / silicon carbide / silicon dioxide powder; the alkyl orthosilicate is methyl orthosilicate or ethyl orthosilicate, and the mass ratio of the alkyl orthosilicate, modified ceramic powder, ethanol, and hydrochloric acid aqueous solution is 10-15:4-6:120-150:20-25; S4. Preparation of a wear-resistant binder: phosphoric acid and aluminum hydroxide were added to water, stirred and mixed, and the N- doped carbon nitride / silicon carbide / silicon dioxide powder obtained in step S3 was added and stirred to react to obtain a wear-resistant binder; the mass ratio of the phosphoric acid, aluminum hydroxide, N- doped carbon nitride / silicon carbide / silicon dioxide powder and water was 55-65:11-13:7-10:25-35; S5. Preparation of aluminum phosphate wear-resistant bricks: ball-milling high-alumina bauxite, sieving, adding the fine high-alumina bauxite obtained in step S4 to the wear-resistant binder, stirring and mixing, machine pressing and calcining to obtain aluminum phosphate wear-resistant bricks; the mass ratio of the fine high-alumina bauxite to the wear-resistant binder is 10:27-35.

2. The preparation method according to claim 1, characterized in that The heating rate of the heating calcination in step S1 is 2-3°C / min, the temperature is raised to 500-600°C, and the calcination time is 4-6h.

3. The preparation method according to claim 1, characterized in that In step S2, the catalyst is a Tris-HCl solution with a pH of 8.5-9, and the heating and stirring reaction is carried out at a temperature of 40-50° C. for 2-4 hours.

4. The preparation method according to claim 1, characterized in that The concentration of the hydrochloric acid aqueous solution in step S3 is 1-2 mol / L, the stirring reaction temperature is 35-45°C, the time is 3-5 hours, the aging time is 5-7 hours, the calcination temperature is 500-700°C, the time is 1-3 hours, and the ball milling time is 1-2 hours.

5. The preparation method according to claim 1, characterized in that The stirring reaction in step S4 is carried out at a temperature of 40-50° C. and for a time of 20-40 minutes.

6. The preparation method according to claim 1, characterized in that The ball milling time in step S5 is 2-4 hours, the sieve mesh size is 500 mesh, the stirring and mixing time is 30-50 minutes, the machine pressing pressure is 100-110 MPa, the time is 15-25 minutes, and the calcination temperature is 450-550° C., and the time is 1-3 hours.

7. The preparation method according to claim 1, characterized in that The specific steps include: S1. Preparation of N-doped carbon nitride: 10-15 parts by weight of urea and 1-2 parts by weight of citric acid were uniformly mixed, heated and calcined at a heating rate of 2-3°C / min to a temperature of 500-600°C for 4-6 hours, cooled to room temperature, and crushed to obtain N-doped carbon nitride; S2. Preparation of modified ceramic powder: 10-12 parts by weight of N-doped carbon nitride obtained in step S1 and 7-10 parts by weight of silicon carbide powder were added to 200 parts by weight of water, 17-22 parts by weight of dopamine hydrochloride and 1-2 parts by weight of a catalyst were added, heated to 40-50 ° C, stirred for 2-4h, centrifuged, washed, and dried to obtain a modified ceramic powder; The catalyst is a Tris-HCl solution with a pH of 8.5-9; S3. Preparation of N-doped carbon nitride / silicon carbide / silicon dioxide powder: Dissolve 10-15 parts by weight of alkyl orthosilicate in 120-150 parts by weight of ethanol, add 4-6 parts by weight of the modified ceramic powder obtained in step S2, stir and mix uniformly, add 20-25 parts by weight of a 1-2 mol / L hydrochloric acid aqueous solution dropwise, stir and react at 35-45°C for 3-5 hours, age for 5-7 hours, dry, calcined at 500-700°C for 1-3 hours, and ball milled for 1-2 hours to obtain N-doped carbon nitride / silicon carbide / silicon dioxide powder; S4. Preparation of a wear-resistant binder: 55-65 parts by weight of phosphoric acid and 11-13 parts by weight of aluminum hydroxide were added to 25-35 parts by weight of water, stirred and mixed, and 7-10 parts by weight of the N- doped carbon nitride / silicon carbide / silicon dioxide powder obtained in step S3 was added, and the reaction was stirred at 40-50 ° C for 20-40min to obtain a wear-resistant binder; S5. Preparation of aluminum phosphate wear-resistant bricks: ball mill high-alumina bauxite for 2-4 hours, pass through a 500-mesh sieve, and add the wear-resistant binder in step S4 to 10 parts by weight of the fine high-alumina bauxite. Stir and mix for 30-50 minutes, press at 100-110 MPa for 15-25 minutes, and calcinate at 450-550°C for 1-3 hours to produce aluminum phosphate wear-resistant bricks.

8. Aluminum phosphate wear-resistant brick prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the aluminum phosphate wear-resistant brick according to claim 8 in the preparation of rotary kiln lining bricks.

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