High-strength refractory brick for garbage incinerator and preparation method of high-strength refractory brick

Abstract

The invention relates to the technical field of refractory brick production, and discloses a high-strength refractory brick for a garbage incinerator and a preparation method thereof.The high-strength refractory brick is prepared from, by mass, 32-45 parts of fly ash, 18-30 parts of kieselguhr, 6-10 parts of modified aluminum silicate fibers, 20-30 parts of nano zirconium silicate loaded crystalline flake graphite powder, 7-10 parts of metal oxide and 1-3 parts of auxiliary materials. Fly ash and diatomite are used as raw materials, modified aluminum silicate fiber, nano zirconium silicate loaded crystalline flake graphite powder, metal oxide and auxiliary materials are compounded, the prepared refractory brick has high mechanical strength, fire resistance and oxidation resistance, the product quality of the refractory brick is improved, the refractory brick is prevented from cracking in the waste incineration process, and the service life of the refractory brick is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of refractory brick production, in particular to a high-strength refractory brick for a garbage incinerator and a preparation method thereof. Background Art

[0002] Waste incineration is suitable for domestic waste, medical waste, general industrial waste, etc. Compared with landfill and composting, waste incineration saves more land and does not cause surface water and groundwater pollution. Waste incinerators are usually made of refractory bricks, which are refractory materials made by burning refractory clay or other refractory raw materials. They are light yellow or brown and can withstand high temperatures of 1580-1770℃.

[0003] The refractory bricks prepared by mixing fly ash, diatomaceous earth, fillers and additives, pressing, molding, drying and calcining have strong thermal stability, good slag resistance, low cost and excellent mechanical properties. However, the refractory bricks have insufficient strength and high temperature resistance during use and are very easy to crack. By adding aluminum silicate fiber to the refractory bricks, it can play a role in bearing stress and improve the mechanical strength of refractory bricks used in waste incinerators. However, mullite and cristobalite are easily precipitated during the high-temperature calcination of aluminum silicate fiber, which makes the aluminum silicate fiber brittle and affects the strength of the refractory bricks. Summary of the Invention

[0004] The present invention provides a high-strength refractory brick for a garbage incinerator and a preparation method thereof, which solves the problem that the refractory brick has insufficient strength and high-temperature resistance and is very easy to crack during use.

[0005] The technical solution of the present invention:

[0006] A high-strength refractory brick for a waste incinerator, comprising the following raw materials in parts by weight: 32-45 parts of fly ash, 18-30 parts of diatomaceous earth, 6-10 parts of modified aluminum silicate fiber, 20-30 parts of nano-zirconium silicate-loaded flake graphite powder, 7-10 parts of metal oxide, and 1-3 parts of auxiliary materials;

[0007] The modified aluminum silicate fiber is obtained by forming a silicon dioxide coating layer on the surface of the aluminum silicate fiber and then reacting it with cobalt nitrate hexahydrate, ammonium fluoride and urea.

[0008] The nano zirconium silicate-loaded flake graphite powder is obtained by coating the nano zirconium silicate on the surface of the flake graphite powder via carboxymethyl cellulose.

[0009] A method for preparing high-strength refractory bricks for a waste incinerator comprises the following steps:

[0010] S1 fly ash, diatomaceous earth, modified aluminum silicate fiber, nano-zirconium silicate flake graphite powder, metal oxides are mixed and stirred at 500-800r / min for 20-40min, the auxiliary materials are added, and stirring is continued for 20-40min to obtain a mixture;

[0011] S2. The mixture is pressed into shape, dried, calcined, and then cooled to room temperature to obtain high-strength refractory bricks.

[0012] Furthermore, in step S2, the pressing pressure is 30-50 MPa; the drying temperature is 80-100° C., and the drying time is 10-12 h.

[0013] Furthermore, in step S2, the calcination temperature is 1200-1300° C., and the calcination time is 6-8 hours.

[0014] Furthermore, the density of fly ash is 1.8-2g / cm 3 , the magnesium oxide content in fly ash is 0.5-1%.

[0015] Furthermore, diatomaceous earth contains 78-85% silicon dioxide and 0.3-0.7% iron oxide.

[0016] Furthermore, the metal oxide is selected from any one of aluminum oxide, calcium oxide and magnesium oxide.

[0017] Furthermore, the auxiliary material is prepared by mixing a binder and water in a mass ratio of (1-2):(5-10).

[0018] Furthermore, the binder is selected from aluminum phosphate or aluminum hydroxide.

[0019] Furthermore, the modified aluminum silicate fiber is specifically prepared by the following steps:

[0020] A1. Aluminum silicate fibers were added to ethanol and deionized water. After sonication, tetraethyl orthosilicate and an aqueous sulfuric acid solution were added. The mixture was stirred at 45-55°C for 2-5 hours, filtered, washed, and dried to obtain pretreated aluminum silicate fibers.

[0021] A2. Add cobalt nitrate hexahydrate, ammonium fluoride, and urea to deionized water, stir well, add pretreated aluminum silicate fiber, stir, and continue stirring at 120-130°C for 3-5 hours. Cool to room temperature, collect the solid, wash the solid, dry it, and calcine it at 850-950°C for 2-4 hours. Cool to room temperature to obtain modified aluminum silicate fiber.

[0022] Furthermore, during the above-mentioned A1 reaction process, the hydroxyl groups produced by the hydrolysis of tetraethyl orthosilicate can be chemically bonded to the hydroxyl groups on the surface of the aluminum silicate fiber, so that the silica produced by the hydrolysis of tetraethyl orthosilicate is coated on the surface of the aluminum silicate fiber to obtain pretreated aluminum silicate fiber.

[0023] Furthermore, in the above-mentioned reaction process A2, cobalt nitrate hexahydrate undergoes a hydrothermal reaction under the catalysis of ammonium fluoride and urea, so that the cobalt nitrate hexahydrate undergoes dehydroxylation and decarbonization reactions to form cobalt oxide, which is calcined at 900°C so that the formed cobalt oxide can react with the silica on the surface of the pretreated aluminum silicate fiber, and through the silicon-oxygen-cobalt bond, a cobalt silicate layer is synthesized on the surface of the pretreated aluminum silicate fiber to obtain modified aluminum silicate fiber.

[0024] Furthermore, in step A1, the mass ratio of aluminum silicate fiber, ethanol, deionized water, tetraethyl orthosilicate and sulfuric acid aqueous solution is (3.5-4.5):(35-45):(15-25):(2-3):(0.4-0.8).

[0025] Furthermore, in step A2, the mass ratio of cobalt nitrate hexahydrate, ammonium fluoride, urea, deionized water and pretreated aluminum silicate fiber is (0.4-0.6):(0.1-0.2):(0.2-0.4):(45-55):(2-2.6).

[0026] Furthermore, the diameter of the aluminum silicate fiber is 2-4.5 μm and the length is 10-20 mm.

[0027] Furthermore, the nano zirconium silicate loaded flake graphite powder is specifically prepared by the following steps:

[0028] B1. Carboxymethyl cellulose was added to deionized water, stirred, and flake graphite powder was added. The temperature was raised to 40-60 ° C, stirred at 800-1000 r / min for 5-10 min, filtered, washed, and dried to obtain pretreated flake graphite powder.

[0029] B2. The pretreated flake graphite powder and nano-zirconium silicate were added to deionized water, stirred and mixed at 40-60 ° C for 20-30 min, filtered, washed, and dried to obtain flake graphite powder loaded with nano-zirconium silicate.

[0030] Furthermore, during the above-mentioned reaction B1, carboxymethyl cellulose is dissolved in deionized water and has excellent adhesion, and can adhere to the surface of the flake graphite powder, giving the flake graphite powder polar functional groups to obtain pretreated flake graphite powder.

[0031] Furthermore, during the above-mentioned B2 reaction process, the pretreated flake graphite powder contained on the surface of the pretreated flake graphite powder contains a large number of carboxyl functional groups and has adhesiveness, which can adhere nano zirconium silicate to the surface of the pretreated flake graphite powder to obtain flake graphite powder loaded with nano zirconium silicate.

[0032] Furthermore, in step B1, the mass ratio of carboxymethyl cellulose, deionized water and flake graphite powder is (1-2):(45-55):(2.1-2.5).

[0033] Furthermore, in step B2, the mass ratio of pretreated flake graphite powder, nano zirconium silicate and deionized water is (1.5-2.5):(0.5-1.5):(45-55).

[0034] Furthermore, the particle size of the flake graphite powder is 25-35 μm.

[0035] Furthermore, the particle size of the nano zirconium silicate is 50-100 nm.

[0036] The present invention has the following beneficial effects:

[0037] (1) In the technical solution of the present invention, a silica coating layer is formed on the surface of the aluminum silicate fiber, which can provide a large amount of silica on the surface of the aluminum silicate fiber, which is beneficial to the synthesis of cobalt silicate on the surface of the aluminum silicate fiber. In the process of synthesizing cobalt silicate, the provided silica participates in the reaction of synthesizing cobalt silicate, which can avoid excessive consumption of silica in the aluminum silicate fiber, resulting in a decrease in the mechanical properties of the aluminum silicate fiber. In addition, during the sintering process of the refractory brick, the silica on the surface can delay the diffusion reaction of alumina and silica inside the fiber, reduce high-temperature crystallization, and extend the service life.

[0038] (2) In the technical solution of the present invention, pretreated aluminum silicate fiber is mixed with cobalt nitrate hexahydrate, ammonium fluoride and urea to react, so as to synthesize a cobalt silicate layer on the surface of the pretreated aluminum silicate fiber to obtain modified aluminum silicate fiber. On the one hand, the melting point of the synthesized cobalt silicate is higher than that of the aluminum silicate fiber, which improves the high temperature resistance of the aluminum silicate fiber and avoids the precipitation of mullite and cristobalite from the aluminum silicate fiber during high temperature calcination, which causes the aluminum silicate fiber to become brittle. In addition, the cobalt silicate layer and a small amount of silicon dioxide layer on the surface of the aluminum silicate fiber can block oxygen from directly contacting the fiber, reduce high temperature oxidation, and maintain the high temperature stability of the aluminum silicate fiber. On the other hand, the excellent aspect ratio of the aluminum silicate fiber is evenly dispersed in the refractory brick, which plays a role in bearing stress and significantly improves the mechanical strength of the refractory bricks used in waste incinerators.

[0039] (3) In the technical solution of the present invention, nano zirconium silicate is coated on the surface of flake graphite powder by carboxymethyl cellulose to obtain flake graphite powder loaded with nano zirconium silicate. On the one hand, nano zirconium silicate is added to refractory bricks and, after high-temperature sintering, can react with the carbon element in the flake graphite powder to produce a zirconium carbide phase, which fills the gaps in the refractory bricks, thereby improving the density of the refractory bricks and enhancing the mechanical strength of the refractory bricks. On the other hand, nano zirconium silicate is loaded on the surface of the flake graphite powder, thereby increasing the surface roughness of the flake graphite powder and the contact area between the flake graphite powder loaded with nano zirconium silicate and the refractory brick matrix. Moreover, during the high-temperature sintering process, the flake graphite powder partially produces a free graphite phase covering the surface of the refractory brick, thereby improving the oxidation resistance of the refractory bricks and avoiding the alkaline environment in the waste incineration process that easily corrodes the weather-resistant bricks and affects the performance of the refractory bricks. In addition, the flake graphite powder is randomly distributed in the refractory bricks and can absorb the stress generated externally and enhance the mechanical properties of the refractory bricks.

[0040] (4) In the technical solution of the present invention, fly ash and diatomaceous earth are used as raw materials, and modified aluminum silicate fiber, flake graphite powder loaded with nano zirconium silicate, metal oxides and auxiliary materials are compounded to prepare refractory bricks with high mechanical strength, fire resistance and oxidation resistance, thereby improving the product quality of refractory bricks, avoiding cracking of refractory bricks during the waste incineration process, and extending the service life of refractory bricks. DETAILED DESCRIPTION

[0041] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0042] The raw materials used in the examples of the present invention are as follows, and all reagents used are of analytical grade.

[0043] Among them, the density of fly ash is 1.9g / cm 3 , the magnesium oxide content in fly ash is 0.8%.

[0044] Diatomaceous earth contains 82% silicon dioxide and 0.5% iron oxide.

[0045] The metal oxide is aluminum oxide, and the particle size is 0.8 μm.

[0046] The auxiliary material is prepared by mixing a binder and water in a mass ratio of 1.5:8, and the binder is aluminum phosphate.

[0047] The diameter of the aluminum silicate fibers is 3 μm and the length is 15 mm.

[0048] The flake graphite powder has a particle size of 30 μm and is of the brand Malin, which was purchased from Malin Mineral Products Processing Plant in Lingshou County.

[0049] The particle size of nano zirconium silicate is 80nm.

[0050] Example 1

[0051] A high-strength refractory brick for a waste incinerator, comprising the following raw materials in parts by weight: 32 parts of fly ash, 18 parts of diatomaceous earth, 6 parts of modified aluminum silicate fiber, 20 parts of nano-zirconium silicate-loaded flake graphite powder, 7 parts of metal oxide, and 1 part of auxiliary material;

[0052] A method for preparing high-strength refractory bricks for a waste incinerator comprises the following steps:

[0053] S1 fly ash, diatomaceous earth, modified aluminum silicate fiber, nano-zirconium silicate flake graphite powder, metal oxides were mixed and stirred at 500r / min for 20min, the auxiliary materials were added, and stirring was continued for 20min to obtain a mixture;

[0054] S2. The mixture was pressed into shape at 30 MPa, dried at 80°C for 10 h, calcined at 1200°C for 6 h, and cooled to room temperature to obtain high-strength refractory bricks.

[0055] The modified aluminum silicate fiber is specifically prepared by the following steps:

[0056] A1. Aluminum silicate fibers were added to ethanol and deionized water and sonicated at 40 kHz for 1 hour. Tetraethyl orthosilicate and a 2.5% sulfuric acid solution were then added. The mixture was stirred at 45°C for 2 hours. The mixture was filtered, washed three times with deionized water and three times with ethanol, and dried in a 70°C oven for 10 minutes to obtain pretreated aluminum silicate fibers. The mass ratio of aluminum silicate fibers, ethanol, deionized water, tetraethyl orthosilicate, and sulfuric acid solution was 3.5:35:15:2:0.4.

[0057] A2. Add cobalt nitrate hexahydrate, ammonium fluoride, and urea to deionized water, stir well, add pretreated aluminum silicate fiber, stir at 500 r / min for 30 minutes, react at 120°C for 3 hours, cool to room temperature, collect the solid, wash it three times with deionized water, dry it in a 60°C oven for 10 minutes, place it in a Mabo furnace, calcine it at 850°C for 2 hours, and cool to room temperature to obtain modified aluminum silicate fiber; the mass ratio of cobalt nitrate hexahydrate, ammonium fluoride, urea, deionized water, and pretreated aluminum silicate fiber is 0.4:0.1:0.2:45:2.

[0058] The nano-zirconium silicate-loaded flake graphite powder is specifically prepared by the following steps:

[0059] B1. Carboxymethyl cellulose was added to deionized water, stirred, and flake graphite powder was added. The temperature was raised to 40 ° C, stirred at 800 r / min for 5 min, filtered, washed three times with deionized water, and dried in an oven at 60 ° C for 10 min to obtain pretreated flake graphite powder; the mass ratio of carboxymethyl cellulose, deionized water and flake graphite powder was 1:45:2.1;

[0060] B2. Add pretreated flake graphite powder and nano-zirconium silicate to deionized water, stir and mix at 40°C for 20 minutes, filter, wash with deionized water three times, and dry in an oven at 60°C for 10 minutes to obtain flake graphite powder loaded with nano-zirconium silicate; the mass ratio of pretreated flake graphite powder, nano-zirconium silicate and deionized water is 1.5:0.5:45.

[0061] Example 2

[0062] A high-strength refractory brick for a waste incinerator, comprising the following raw materials in parts by weight: 40 parts of fly ash, 24 parts of diatomaceous earth, 8 parts of modified aluminum silicate fiber, 25 parts of nano-zirconium silicate-loaded flake graphite powder, 9 parts of metal oxide, and 2 parts of auxiliary materials;

[0063] A method for preparing high-strength refractory bricks for a waste incinerator comprises the following steps:

[0064] S1 fly ash, diatomaceous earth, modified aluminum silicate fiber, nano-zirconium silicate flake graphite powder, metal oxides were mixed and stirred at 700r / min for 30min, the auxiliary materials were added, and stirring was continued for 30min to obtain a mixture;

[0065] S2. The mixture was pressed into shape at 40 MPa, dried at 90°C for 11 hours, calcined at 1250°C for 7 hours, and cooled to room temperature to obtain high-strength refractory bricks.

[0066] The modified aluminum silicate fiber is specifically prepared by the following steps:

[0067] A1. Aluminum silicate fibers were added to ethanol and deionized water and sonicated at 40 kHz for 1 hour. Tetraethyl orthosilicate and a 2.5% sulfuric acid solution were then added. The mixture was stirred at 50°C for 3 hours. The mixture was filtered, washed three times with deionized water and three times with ethanol, and dried in a 70°C oven for 10 minutes to obtain pretreated aluminum silicate fibers. The mass ratio of aluminum silicate fibers, ethanol, deionized water, tetraethyl orthosilicate, and sulfuric acid solution was 4:40:20:2.5:0.6.

[0068] A2. Add cobalt nitrate hexahydrate, ammonium fluoride, and urea to deionized water, stir well, add pretreated aluminum silicate fiber, stir at 500 r / min for 30 minutes, react at 125°C for 4 hours, cool to room temperature, collect the solid, wash it three times with deionized water, dry it in a 60°C oven for 10 minutes, place it in a Mabo furnace, calcined it at 900°C for 3 hours, and cooled to room temperature to obtain modified aluminum silicate fiber; the mass ratio of cobalt nitrate hexahydrate, ammonium fluoride, urea, deionized water, and pretreated aluminum silicate fiber is 0.5:0.15:0.3:50:2.3.

[0069] The nano-zirconium silicate-loaded flake graphite powder is specifically prepared by the following steps:

[0070] B1. Carboxymethyl cellulose was added to deionized water, stirred, and flake graphite powder was added. The temperature was raised to 50 ° C, stirred at 900 r / min for 8 min, filtered, washed three times with deionized water, and dried in an oven at 60 ° C for 10 min to obtain pretreated flake graphite powder; the mass ratio of carboxymethyl cellulose, deionized water and flake graphite powder was 1.5:50:2.3;

[0071] B2. Add pretreated flake graphite powder and nano-zirconium silicate to deionized water, stir and mix at 50°C for 25 minutes, filter, wash with deionized water three times, and dry in an oven at 60°C for 10 minutes to obtain flake graphite powder loaded with nano-zirconium silicate; the mass ratio of pretreated flake graphite powder, nano-zirconium silicate and deionized water is 2:1:50.

[0072] Example 3

[0073] A high-strength refractory brick for a waste incinerator, comprising the following raw materials in parts by weight: 45 parts of fly ash, 30 parts of diatomaceous earth, 10 parts of modified aluminum silicate fiber, 30 parts of flake graphite powder loaded with nano-zirconium silicate, 10 parts of metal oxide, and 3 parts of auxiliary materials;

[0074] A method for preparing high-strength refractory bricks for a waste incinerator comprises the following steps:

[0075] S1 fly ash, diatomaceous earth, modified aluminum silicate fiber, nano-zirconium silicate flake graphite powder, metal oxides were mixed and stirred at 800r / min for 40min, the auxiliary materials were added, and stirring was continued for 40min to obtain a mixture;

[0076] S2. The mixture was pressed into shape at 50 MPa, dried at 100°C for 12 h, calcined at 1300°C for 8 h, and cooled to room temperature to obtain high-strength refractory bricks.

[0077] The modified aluminum silicate fiber is specifically prepared by the following steps:

[0078] A1. Aluminum silicate fibers were added to ethanol and deionized water and sonicated at 40 kHz for 1 hour. Tetraethyl orthosilicate and a 2.5% sulfuric acid solution were then added. The mixture was stirred at 55°C for 5 hours. The mixture was filtered, washed three times with deionized water and three times with ethanol, and dried in a 70°C oven for 10 minutes to obtain pretreated aluminum silicate fibers. The mass ratio of aluminum silicate fibers, ethanol, deionized water, tetraethyl orthosilicate, and sulfuric acid solution was 4.5:55:25:3:0.8.

[0079] A2. Add cobalt nitrate hexahydrate, ammonium fluoride, and urea to deionized water, stir well, add pretreated aluminum silicate fiber, stir at 500 r / min for 30 minutes, react at 130°C for 5 hours, cool to room temperature, collect the solid, wash it three times with deionized water, dry it in a 60°C oven for 10 minutes, place it in a Mabo furnace, calcined it at 950°C for 4 hours, and cooled to room temperature to obtain modified aluminum silicate fiber; the mass ratio of cobalt nitrate hexahydrate, ammonium fluoride, urea, deionized water, and pretreated aluminum silicate fiber is 0.6:0.2:0.4:55:2.6.

[0080] The nano-zirconium silicate-loaded flake graphite powder is specifically prepared by the following steps:

[0081] B1. Carboxymethyl cellulose was added to deionized water, stirred, and flake graphite powder was added. The temperature was raised to 60 ° C, stirred at 1000 r / min for 10 min, filtered, washed three times with deionized water, and dried in an oven at 60 ° C for 10 min to obtain pretreated flake graphite powder; the mass ratio of carboxymethyl cellulose, deionized water and flake graphite powder was 2:55:2.5;

[0082] B2. Add pretreated flake graphite powder and nano-zirconium silicate to deionized water, stir and mix at 60°C for 30 minutes, filter, wash with deionized water three times, and dry in an oven at 60°C for 10 minutes to obtain flake graphite powder loaded with nano-zirconium silicate; the mass ratio of pretreated flake graphite powder, nano-zirconium silicate and deionized water is 2.5:1.5:55.

[0083] Comparative Example 1

[0084] A high-strength refractory brick for a waste incinerator, comprising the following raw materials in parts by weight: 45 parts of fly ash, 30 parts of diatomaceous earth, 10 parts of modified aluminum silicate fiber, 30 parts of flake graphite powder loaded with nano-zirconium silicate, 10 parts of metal oxide, and 3 parts of auxiliary materials;

[0085] A method for preparing high-strength refractory bricks for a waste incinerator comprises the following steps:

[0086] S1 fly ash, diatomaceous earth, modified aluminum silicate fiber, nano-zirconium silicate flake graphite powder, metal oxides were mixed and stirred at 800r / min for 40min, the auxiliary materials were added, and stirring was continued for 40min to obtain a mixture;

[0087] S2. The mixture was pressed into shape at 50 MPa, dried at 100°C for 12 h, calcined at 1300°C for 8 h, and cooled to room temperature to obtain high-strength refractory bricks.

[0088] The modified aluminum silicate fiber is specifically prepared by the following steps:

[0089] Cobalt nitrate hexahydrate, ammonium fluoride and urea are added to deionized water, stirred evenly, and aluminum silicate fiber is added. The mixture is stirred at 500 r / min for 30 minutes, reacted at 130°C for 5 hours, cooled to room temperature, and the solid is collected. The solid is washed three times with deionized water, dried in an oven at 60°C for 10 minutes, placed in a furnace, calcined at 950°C for 4 hours, and cooled to room temperature to obtain modified aluminum silicate fiber. The mass ratio of cobalt nitrate hexahydrate, ammonium fluoride, urea, deionized water and aluminum silicate fiber is 0.6:0.2:0.4:55:2.6.

[0090] The nano-zirconium silicate-loaded flake graphite powder is specifically prepared by the following steps:

[0091] B1. Carboxymethyl cellulose was added to deionized water, stirred, and flake graphite powder was added. The temperature was raised to 60 ° C, stirred at 1000 r / min for 10 min, filtered, washed three times with deionized water, and dried in an oven at 60 ° C for 10 min to obtain pretreated flake graphite powder; the mass ratio of carboxymethyl cellulose, deionized water and flake graphite powder was 2:55:2.5;

[0092] B2. Add pretreated flake graphite powder and nano-zirconium silicate to deionized water, stir and mix at 60°C for 30 minutes, filter, wash with deionized water three times, and dry in an oven at 60°C for 10 minutes to obtain flake graphite powder loaded with nano-zirconium silicate; the mass ratio of pretreated flake graphite powder, nano-zirconium silicate and deionized water is 2.5:1.5:55.

[0093] Comparative Example 2

[0094] A high-strength refractory brick for a waste incinerator, comprising the following raw materials in parts by weight: 45 parts of fly ash, 30 parts of diatomaceous earth, 10 parts of pretreated aluminum silicate fiber, 30 parts of flake graphite powder loaded with nano-zirconium silicate, 10 parts of metal oxide, and 3 parts of auxiliary materials;

[0095] A method for preparing high-strength refractory bricks for a waste incinerator comprises the following steps:

[0096] S1. The fly ash, diatomaceous earth, pretreated aluminum silicate fiber, nano-zirconium silicate flake graphite powder, metal oxides were mixed and stirred at 800r / min for 40min, the auxiliary materials were added, and stirring was continued for 40min to obtain a mixture;

[0097] S2. The mixture was pressed into shape at 50 MPa, dried at 100°C for 12 h, calcined at 1300°C for 8 h, and cooled to room temperature to obtain high-strength refractory bricks.

[0098] The pretreated aluminum silicate fiber is specifically prepared by the following steps:

[0099] Aluminum silicate fibers were added to ethanol and deionized water, ultrasonicated at 40 kHz for 1 hour, tetraethyl orthosilicate and a 2.5% sulfuric acid aqueous solution were added, stirred and reacted at 55° C. for 5 hours, filtered, washed three times with deionized water, washed three times with ethanol, and dried in an oven at 70° C. for 10 minutes to obtain pretreated aluminum silicate fibers; the mass ratio of aluminum silicate fibers, ethanol, deionized water, tetraethyl orthosilicate, and sulfuric acid aqueous solution was 4.5:55:25:3:0.8;

[0100] The nano-zirconium silicate-loaded flake graphite powder is specifically prepared by the following steps:

[0101] B1. Carboxymethyl cellulose was added to deionized water, stirred, and flake graphite powder was added. The temperature was raised to 60 ° C, stirred at 1000 r / min for 10 min, filtered, washed three times with deionized water, and dried in an oven at 60 ° C for 10 min to obtain pretreated flake graphite powder; the mass ratio of carboxymethyl cellulose, deionized water and flake graphite powder was 2:55:2.5;

[0102] B2. Add pretreated flake graphite powder and nano-zirconium silicate to deionized water, stir and mix at 60°C for 30 minutes, filter, wash with deionized water three times, and dry in an oven at 60°C for 10 minutes to obtain flake graphite powder loaded with nano-zirconium silicate; the mass ratio of pretreated flake graphite powder, nano-zirconium silicate and deionized water is 2.5:1.5:55.

[0103] Comparative Example 3

[0104] A high-strength refractory brick for a waste incinerator, comprising the following raw materials in parts by weight: 45 parts of fly ash, 30 parts of diatomaceous earth, 10 parts of modified aluminum silicate fiber, 30 parts of flake graphite powder loaded with nano-zirconium silicate, 10 parts of metal oxide, and 3 parts of auxiliary materials;

[0105] A method for preparing high-strength refractory bricks for a waste incinerator comprises the following steps:

[0106] S1 fly ash, diatomaceous earth, modified aluminum silicate fiber, nano-zirconium silicate flake graphite powder, metal oxides were mixed and stirred at 800r / min for 40min, the auxiliary materials were added, and stirring was continued for 40min to obtain a mixture;

[0107] S2. The mixture was pressed into shape at 50 MPa, dried at 100°C for 12 h, calcined at 1300°C for 8 h, and cooled to room temperature to obtain high-strength refractory bricks.

[0108] The modified aluminum silicate fiber is specifically prepared by the following steps:

[0109] A1. Aluminum silicate fibers were added to ethanol and deionized water and sonicated at 40 kHz for 1 hour. Tetraethyl orthosilicate and a 2.5% sulfuric acid solution were then added. The mixture was stirred at 55°C for 5 hours. The mixture was filtered, washed three times with deionized water and three times with ethanol, and dried in a 70°C oven for 10 minutes to obtain pretreated aluminum silicate fibers. The mass ratio of aluminum silicate fibers, ethanol, deionized water, tetraethyl orthosilicate, and sulfuric acid solution was 4.5:55:25:3:0.8.

[0110] A2. Add cobalt nitrate hexahydrate, ammonium fluoride, and urea to deionized water, stir well, add pretreated aluminum silicate fiber, stir at 500 r / min for 30 minutes, react at 130°C for 5 hours, cool to room temperature, collect the solid, wash it three times with deionized water, dry it in a 60°C oven for 10 minutes, place it in a Mabo furnace, calcined it at 950°C for 4 hours, and cooled to room temperature to obtain modified aluminum silicate fiber; the mass ratio of cobalt nitrate hexahydrate, ammonium fluoride, urea, deionized water, and pretreated aluminum silicate fiber is 0.6:0.2:0.4:55:2.6.

[0111] The nano-zirconium silicate-loaded flake graphite powder is specifically prepared by the following steps:

[0112] Flake graphite powder and nano-zirconium silicate were added to deionized water, stirred and mixed at 60°C for 30 minutes, filtered, washed with deionized water three times, and dried in an oven at 60°C for 10 minutes to obtain flake graphite powder loaded with nano-zirconium silicate; the mass ratio of flake graphite powder, nano-zirconium silicate and deionized water was 2.5:1.5:55.

[0113] Comparative Example 4

[0114] A high-strength refractory brick for a waste incinerator, comprising the following raw materials in parts by weight: 45 parts of fly ash, 30 parts of diatomaceous earth, 10 parts of modified aluminum silicate fiber, 30 parts of pretreated flake graphite powder, 10 parts of metal oxide, and 3 parts of auxiliary materials;

[0115] A method for preparing high-strength refractory bricks for a waste incinerator comprises the following steps:

[0116] S1 fly ash, diatomaceous earth, modified aluminum silicate fiber, pretreated flake graphite powder, metal oxides were mixed and stirred at 800r / min for 40min, the auxiliary materials were added, and stirring was continued for 40min to obtain a mixture;

[0117] S2. The mixture was pressed into shape at 50 MPa, dried at 100°C for 12 h, calcined at 1300°C for 8 h, and cooled to room temperature to obtain high-strength refractory bricks.

[0118] The modified aluminum silicate fiber is specifically prepared by the following steps:

[0119] A1. Aluminum silicate fibers were added to ethanol and deionized water and sonicated at 40 kHz for 1 hour. Tetraethyl orthosilicate and a 2.5% sulfuric acid solution were then added. The mixture was stirred at 55°C for 5 hours. The mixture was filtered, washed three times with deionized water and three times with ethanol, and dried in a 70°C oven for 10 minutes to obtain pretreated aluminum silicate fibers. The mass ratio of aluminum silicate fibers, ethanol, deionized water, tetraethyl orthosilicate, and sulfuric acid solution was 4.5:55:25:3:0.8.

[0120] A2. Add cobalt nitrate hexahydrate, ammonium fluoride, and urea to deionized water, stir well, add pretreated aluminum silicate fiber, stir at 500 r / min for 30 minutes, react at 130°C for 5 hours, cool to room temperature, collect the solid, wash it three times with deionized water, dry it in a 60°C oven for 10 minutes, place it in a Mabo furnace, calcined it at 950°C for 4 hours, and cooled to room temperature to obtain modified aluminum silicate fiber; the mass ratio of cobalt nitrate hexahydrate, ammonium fluoride, urea, deionized water, and pretreated aluminum silicate fiber is 0.6:0.2:0.4:55:2.6.

[0121] The pretreated flake graphite powder is specifically prepared by the following steps:

[0122] Carboxymethyl cellulose was added to deionized water, stirred evenly, flake graphite powder was added, the temperature was raised to 60°C, stirred at 1000 r / min for 10 min, filtered, washed with deionized water 3 times, and dried in an oven at 60°C for 10 min to obtain pretreated flake graphite powder; the mass ratio of carboxymethyl cellulose, deionized water and flake graphite powder was 2:55:2.5.

[0123] The performance of the high-strength refractory bricks prepared in Examples 1-3 and Comparative Examples 1-4 was tested.

[0124] Compressive strength test: The compressive strength of the high-strength refractory bricks prepared above was tested in accordance with GB / T5072-2008 "Test method for compressive strength of refractory materials at room temperature".

[0125] Flexural strength test: The room temperature flexural strength of the high-strength refractory bricks prepared above was tested in accordance with GB / T3001-2017 Test method for flexural strength of refractory materials at room temperature.

[0126] High temperature flexural strength test: According to GB / T3002-2017 Test method for high temperature flexural strength of refractory materials, the high strength refractory bricks prepared above were treated at 1400°C for 30 minutes to test the high temperature flexural strength of the refractory bricks.

[0127] Oxidation resistance test: The high-strength refractory bricks prepared above (size 240×115×50 mm, thickness D0=50 mm) were treated at 1250°C for 5 h, cooled to room temperature, and the thickness (D1) of the refractory bricks after heat treatment was measured with a vernier caliper. The surface oxidation thickness was recorded, and the oxidation thickness = D1-D0.

[0128] As shown in Table 1 below.

[0129] Table 1 Performance test of high strength refractory bricks prepared in Examples 1-3 and Comparative Examples 1-4

[0130]

[0131] It can be seen from the data in Table 1 that the high-strength refractory bricks prepared in Examples 1-3 have good high-temperature oxidation resistance and mechanical strength.

[0132] In Comparative Example 1, the pretreated aluminum silicate fiber was replaced with modified aluminum silicate fiber prepared by aluminum silicate fiber and added to the high-strength refractory brick, and its mechanical properties decreased, which proved that a silica coating layer was formed on the surface of the aluminum silicate fiber. During the reaction process of synthesizing cobalt silicate, excessive consumption of silica in the aluminum silicate fiber can be avoided, resulting in a decrease in the mechanical properties of the aluminum silicate fiber. In addition, during the sintering process of the refractory brick, the silica on the surface can delay the diffusion reaction of alumina and silica inside the fiber, reduce high-temperature crystallization, and extend the service life.

[0133] In Comparative Example 2, the modified aluminum silicate fiber was replaced with pretreated aluminum silicate fiber and added to the high-strength refractory bricks, and its mechanical properties and oxidation resistance decreased, proving that the synthesis of a cobalt silicate layer on the surface of the pretreated aluminum silicate fiber improves the high-temperature resistance of the aluminum silicate fiber, and the cobalt silicate layer and a small amount of silicon dioxide layer on the surface of the aluminum silicate fiber can block oxygen from directly contacting the fiber, reduce high-temperature oxidation, maintain the high-temperature stability of the aluminum silicate fiber, and improve the mechanical properties of the high-strength refractory bricks.

[0134] In Comparative Example 3, the pretreated flake graphite powder was replaced with flake graphite powder prepared by loading nano-zirconium silicate with flake graphite powder and added to high-strength refractory bricks. The mechanical properties of the flake graphite powder decreased, proving that carboxymethyl cellulose adhered to the surface of the flake graphite powder, giving the flake graphite powder polar functional groups, which was conducive to the adhesion of nano-zirconium silicate to the surface of the flake graphite powder, so that the nano-zirconium silicate was evenly distributed in the refractory bricks through the flake graphite powder, thereby enhancing the mechanical strength of the refractory bricks.

[0135] In Comparative Example 4, the flake graphite powder loaded with nano-zirconium silicate was replaced with pretreated flake graphite powder and added to high-strength refractory bricks, and its mechanical properties and oxidation resistance decreased, proving that the nano-zirconium silicate was loaded on the surface of the flake graphite powder, increasing the surface roughness of the flake graphite powder, increasing the contact area between the flake graphite powder loaded with nano-zirconium silicate and the refractory brick matrix, and improving the mechanical properties of the refractory bricks. In addition, during the high-temperature sintering process, the flake graphite powder partially produces free graphite phase covering the surface of the refractory bricks, thereby improving the oxidation resistance of the refractory bricks.

[0136] Throughout the specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0137] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in similar ways. As long as they do not deviate from the invention or exceed the scope defined by the claims, they should all fall within the scope of protection of the present invention.

Claims

1. A high-strength refractory brick for a waste incinerator, characterized in that: The invention comprises the following raw materials in parts by weight: 32-45 parts of fly ash, 18-30 parts of diatomaceous earth, 6-10 parts of modified aluminum silicate fiber, 20-30 parts of flake graphite powder loaded with nano zirconium silicate, 7-10 parts of metal oxide and 1-3 parts of auxiliary materials; The modified aluminum silicate fiber is obtained by forming a silicon dioxide coating layer on the surface of the aluminum silicate fiber and then reacting it with cobalt nitrate hexahydrate, ammonium fluoride and urea. The nano zirconium silicate-loaded flake graphite powder is obtained by coating the nano zirconium silicate on the surface of the flake graphite powder via carboxymethyl cellulose.

2. The high-strength refractory brick for a waste incinerator according to claim 1, characterized in that: The modified aluminum silicate fiber is specifically prepared by the following steps: A1. Aluminum silicate fibers were added to ethanol and deionized water. After sonication, tetraethyl orthosilicate and an aqueous sulfuric acid solution were added. The mixture was stirred at 45-55°C for 2-5 hours, filtered, washed, and dried to obtain pretreated aluminum silicate fibers. A2. Add cobalt nitrate hexahydrate, ammonium fluoride, and urea to deionized water, stir well, add pretreated aluminum silicate fiber, stir, and continue stirring at 120-130°C for 3-5 hours. Cool to room temperature, collect the solid, wash the solid, dry it, and calcine it at 850-950°C for 2-4 hours. Cool to room temperature to obtain modified aluminum silicate fiber.

3. The high-strength refractory brick for a waste incinerator according to claim 2, characterized in that: In step A1, the mass ratio of the aluminum silicate fiber, ethanol, deionized water, tetraethyl orthosilicate and sulfuric acid aqueous solution is (3.5-4.5):(35-45):(15-25):(2-3):(0.4-0.8).

4. The high-strength refractory brick for a waste incinerator according to claim 2, characterized in that: In step A2, the mass ratio of the cobalt nitrate hexahydrate, ammonium fluoride, urea, deionized water and pretreated aluminum silicate fiber is (0.4-0.6):(0.1-0.2):(0.2-0.4):(45-55):(2-2.6).

5. The high-strength refractory brick for a waste incinerator according to claim 1, characterized in that: The nano-zirconium silicate-loaded flake graphite powder is specifically prepared by the following steps: B1. Carboxymethyl cellulose was added to deionized water, stirred, and flake graphite powder was added. The temperature was raised to 40-60 ° C, stirred at 800-1000 r / min for 5-10 min, filtered, washed, and dried to obtain pretreated flake graphite powder. B2. The pretreated flake graphite powder and nano-zirconium silicate were added to deionized water, stirred and mixed at 40-60 ° C for 20-30 min, filtered, washed, and dried to obtain flake graphite powder loaded with nano-zirconium silicate.

6. The high-strength refractory brick for a waste incinerator according to claim 5, characterized in that: In step B1, the mass ratio of the carboxymethyl cellulose, deionized water and flake graphite powder is (1-2):(45-55):(2.1-2.5).

7. The high-strength refractory brick for a waste incinerator according to claim 5, characterized in that: In step B2, the mass ratio of the pretreated flake graphite powder, nano zirconium silicate and deionized water is (1.5-2.5):(0.5-1.5):(45-55).

8. The high-strength refractory brick for a waste incinerator according to claim 1, characterized in that: The metal oxide is selected from any one of aluminum oxide, calcium oxide and magnesium oxide.

9. The high-strength refractory brick for a waste incinerator according to claim 1, characterized in that: The auxiliary material is prepared by mixing a binder and water in a mass ratio of (1-2):(5-10); The binder is selected from aluminum phosphate or aluminum hydroxide.

10. A method for preparing the flame-retardant and high-temperature-resistant nano-ceramic micro-bead high-strength refractory brick according to any one of claims 1 to 9, characterized in that: The method comprises the following preparation steps: S1 fly ash, diatomaceous earth, modified aluminum silicate fiber, nano-zirconium silicate flake graphite powder, metal oxides are mixed and stirred at 500-800r / min for 20-40min, the auxiliary materials are added, and stirring is continued for 20-40min to obtain a mixture; S2. The mixture is pressed into shape, dried, calcined, and then cooled to room temperature to obtain high-strength refractory bricks.

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