Refractory material containing waste magnesium-calcium brick and preparation method thereof

Abstract

The application relates to the technical field of refractory materials, in particular to a refractory material containing waste magnesium-calcium bricks and a preparation method thereof, which comprises the following components: composite aggregate, calcium aluminate cement, urea-formaldehyde resin-aluminum dihydrogen phosphate, active alpha-Al2O3 micro powder, silicon micro powder and sodium tripolyphosphate. In the room temperature spraying maintenance and low-temperature working stage, the hydrophobic effect of fluorinated polyphosphazene and the modified zirconia sol prevent the hydration of free CaO in the waste magnesium-calcium bricks and the OH ‑ Erosion, carboxyethyl silanol and carboxylic acid groups of polyethylene glycol monomethyl ether improve the compatibility and wettability of the composite aggregate and the cement paste. With the temperature rising, the aluminum dihydrogen phosphate forms a viscous liquid phase to wrap the aggregate, providing temporary protection. With the temperature continuing to rise, the zirconia, nano-Al2O3, CaO and MgO react to generate CaZrO3 and MgAl2O3, the aluminum dihydrogen phosphate reacts with the nano-Al2O3 in the system to generate AlPO4, and the CaZrO3, MgAl2O3 and AlPO4 constitute a multiphase refractory structure, further improving the refractory performance of the refractory material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of refractory materials, and particularly relates to a refractory material containing waste magnesium-calcium bricks and a preparation method thereof. BACKGROUND

[0002] The refractory material containing waste magnesium-calcium bricks has high content of MgO and CaO, is similar to the body of the furnace lining, has good compatibility, and has strong hanging kiln skin, so that the service life of the furnace lining can be effectively prolonged, and is often made into a spray furnace material or a gunning material of an electric furnace or a refining furnace. When the gunning material is prepared, cement is usually combined. Since the waste magnesium-calcium bricks contain a large amount of free CaO, water hydration occurs when water is encountered, which causes the spray coating material to fail, so that the waste magnesium-calcium bricks need to be subjected to surface wrapping treatment. However, a single organic wrapping layer can seriously weaken the bonding force between the aggregate and the cement matrix, resulting in low spray adhesion rate and easy falling off. The inorganic wrapping layer is often brittle and is easy to produce cracks under construction impact. SUMMARY

[0003] (1) Technical problem to be solved

[0004] The purpose of the present application is to provide a refractory material containing waste magnesium-calcium bricks and a preparation method thereof, so as to solve the problem that the waste magnesium-calcium bricks cause the bonding force between the spray coating material and the cement to decrease and the adhesion rate to be low when the waste magnesium-calcium bricks are wrapped against hydration.

[0005] (2) Technical scheme

[0006] To achieve the above-mentioned purpose, on the one hand, the present application provides a refractory material containing waste magnesium-calcium bricks, which comprises the following components in parts by weight: composite aggregate 50-65 parts, calcium aluminate cement 15-25 parts, urea-formaldehyde resin-aluminum dihydrogen phosphate 2-5 parts, active alpha-Al2O3 micro powder 5-10 parts, silicon micro powder 3-5 parts, and sodium tripolyphosphate 0.1-0.3 parts.

[0007] The composite aggregate anchors the waste magnesium-calcium bricks by carboxyethyl silane triol, grafts fluorinated polyphosphazene to form a hydrophobic protective layer, is wrapped by modified zirconia sol, and finally introduces nano-Al2O3.

[0008] The modified zirconia sol is grafted with polyethylene glycol monomethyl ether.

[0009] Further, the composite aggregate comprises the following components in parts by weight: waste magnesium-calcium bricks 80-100 parts, carboxyethyl silane triol 2-3 parts, fluorinated polyphosphazene 3-5 parts, modified zirconia sol 5-8 parts, and nano-Al2O3 3-5 parts.

[0010] Further, the preparation method of the modified zirconia sol comprises the following steps:

[0011] S11. Dissolve zirconium hydroxide in anhydrous ethanol, heat in water bath, continuously stir, add acetylacetone ethanol solution, dropwise add triethylamine ethanol solution, adjust pH to 8-10, continue to stir the reaction, obtain zirconium oxide sol;

[0012] S12. Mix polyethylene glycol monomethyl ether and gamma-(methacryloyloxy) propyl trimethoxysilane in anhydrous ethanol, add organic tin as catalyst, reflux reaction, obtain activated polyethylene glycol monomethyl ether solution;

[0013] S13. Slowly drop the activated polyethylene glycol monomethyl ether solution into the zirconium oxide sol under stirring, continuously stir the reaction, seal the obtained reaction liquid at room temperature, concentrate by rotary evaporation, obtain modified zirconium oxide sol.

[0014] Further, the mass ratio of polyethylene glycol monomethyl ether to zirconium hydroxide is 1-1.25:1.

[0015] Further, the preparation method of the composite aggregate comprises the following steps:

[0016] S21. Crush and sieve the waste magnesium-calcium brick, repeatedly wash with deionized water and ethanol, immerse in dilute phosphoric acid, wash with deionized water, dry in an oven, obtain aggregate;

[0017] S22. Add carboxyethyl silane triol into ethanol / deionized water mixed solvent, adjust pH with dilute acetic acid, hydrolyze at room temperature under stirring, immerse in the aggregate, filter, solidify, obtain first compound;

[0018] S23. Add fluorinated polyphosphazene into ethanol / acetone mixed solvent, heat in water bath, stir to dissolve, obtain fluorinated polyphosphazene solution, add the first compound into fluidized bed, spray with fluorinated polyphosphazene solution, obtain second compound;

[0019] S24. Dilute the modified zirconium oxide sol with deionized water to solid content of 10%, add sodium hexametaphosphate, obtain diluted modified zirconium oxide sol, place the second compound in a roller, spray the diluted modified zirconium oxide sol, stand at room temperature, heat treatment and solidification, obtain third compound;

[0020] S25. Dissolve sodium hexametaphosphate in deionized water, add nano-Al2O3 and ultrasonic disperse, continue to stir, obtain nano-Al2O3 dispersion liquid, add the third compound, stir and immerse, filter and dry, obtain composite aggregate.

[0021] Further, the aggregate contains three particle sizes of 0.5-1 mm, 1-3 mm, and 3-5 mm, with a mass ratio of 2:5:3.

[0022] Further, the preparation method of the urea-formaldehyde resin-aluminum dihydrogen phosphate comprises the following steps:

[0023] S31. urea, formaldehyde solution and deionized water are mixed, pH is adjusted with triethanolamine, and the reaction is stirred to obtain a urea-formaldehyde resin prepolymer solution;

[0024] S32. aluminum dihydrogen phosphate is dispersed in deionized water, sodium dodecyl sulfate is added, and stirring is uniformly performed to obtain a suspension;

[0025] S33. the suspension is poured into the urea-formaldehyde resin prepolymer solution, stirring is continuously performed, dilute hydrochloric acid is added to adjust pH, continuous reaction is performed, the obtained reaction solution is adjusted to neutral pH with sodium hydroxide solution, filtration is performed, washing is performed with deionized water and ethanol, and vacuum drying is performed to obtain urea-formaldehyde resin-aluminum dihydrogen phosphate.

[0026] In another aspect, based on the same inventive concept, the application further provides a preparation method of a refractory material containing waste magnesium-calcium bricks, which is applied to the refractory material containing waste magnesium-calcium bricks and includes the following steps:

[0027] S1. The composite aggregate is placed in a mixer, active alpha-Al2O3 micro powder and silicon micro powder are added, low-speed stirring is performed for uniform mixing, calcium aluminate cement is slowly added, medium-speed stirring is performed for uniform mixing, sodium tripolyphosphate and urea-formaldehyde resin-aluminum dihydrogen phosphate are continuously added, and continuous stirring is performed to obtain a mixture, and the mixture is sieved to obtain the refractory material.

[0028] In the preparation of the refractory material containing waste magnesium-calcium bricks, the calcium aluminate cement is combined with the waste magnesium-calcium bricks to prepare a gunning material, in order to prevent the hydration expansion of free CaO in the waste magnesium-calcium bricks and the destruction of the structure of the refractory material, resulting in difficult construction and the decline of the high-temperature volume stability and strength of the refractory material, therefore, the waste magnesium-calcium bricks need to be wrapped with hydrophobic fluorinated polyphosphazene to form a dense physical barrier to prevent hydration, but due to its high hydrophobicity, the compatibility and bonding force with the cement paste are poor, and it is easy to agglomerate, therefore, carboxyethyl silanetriol is first anchored on the aggregate, and then fluorinated polyphosphazene is grafted to form a hydrophobic protective layer, the carboxylic acid groups of the carboxyethyl silanetriol are exposed outward and can form stable calcium carboxylate complexes with Ca 2+ The hydrophilicity of the carboxylic acid groups is improved to improve the compatibility and wettability with the cement paste.

[0029] The strong alkaline environment caused by the hydration of the calcium aluminate cement makes Ca 2+ preferentially combine with OH - , and the invasion of OH - will cause the waste magnesium-calcium bricks to be damaged by alkali. On the one hand, the slow release of aluminum dihydrogen phosphate from the urea-formaldehyde resin-aluminum dihydrogen phosphate added therein can provide H + to neutralize the OH -Its products can seal the pores of refractory materials, and its setting-promoting effect facilitates spraying. On the other hand, zirconium itself reacts with OH... - The low reactivity allows it to remain stable over a long period. Grafting polyethylene glycol monomethyl ether creates steric hindrance, further hindering the reaction of OH-. - Erosion of waste magnesium-calcium bricks and reduction of the effects of a highly alkaline environment on carboxylic acid groups and Ca 2+ The effect of coordination. At the same time, the modified zirconia sol grafted with polyethylene glycol monomethyl ether provides hydrophilic flexibility, further enhancing the compatibility between aggregate and cement matrix. Moreover, the flexibility of the long chain of polyethylene glycol monomethyl ether acts as a stress buffer layer, absorbing the internal stress generated at the interface due to cement hydration shrinkage, preventing interface cracking, and thus enhancing the bonding strength.

[0030] Since the fluorinated polyphosphazene and polyethylene glycol monomethyl ether decompose at the temperatures at which refractory materials are used as spraying materials, the introduction of nano-Al2O3 into the aggregate allows the fluorinated polyphosphazene and modified zirconium oxide sol to effectively block moisture and OH radicals during the room temperature spraying and curing process up to the low-temperature working stage. - In the process of intrusion, carboxyethyl silane triol and polyethylene glycol monomethyl ether improve the compatibility and adhesion of the spray coating, achieving good workability and initial bonding strength. As the working temperature increases, fluorinated polyphosphazene, carboxyethyl silane triol and polyethylene glycol monomethyl ether begin to decompose. At this time, the added aluminum dihydrogen phosphate forms a viscous liquid phase to encapsulate the aggregate, providing temporary protection. When the temperature continues to rise, zirconium oxide reacts with CaO to generate a stable CaZrO3 phase. The added nano-Al2O3 reacts with MgO on the surface of the aggregate to generate MgAl2O3, forming a continuous, dense, and highly refractory sintered layer in situ. Furthermore, aluminum dihydrogen phosphate can react with nano-Al2O3 and MgO in the system at high temperatures to generate high-temperature stable phases such as AlPO4 and magnesium aluminum phosphate. AlPO4 can promote the liquid phase sintering between nano-Al2O3 particles at high temperatures, thereby improving the flexural strength of the material. At the same time, CaZrO3, MgAl2O3 and AlPO4 constitute a multiphase refractory structure, further improving the refractory performance of the refractory material.

[0031] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0032] 1. Fluorinated polyphosphazene's hydrophobic effect prevents the hydration of free CaO in waste magnesium-calcium bricks; the carboxylic acid groups of carboxyethylsilanetriol improve the compatibility and wettability of the composite aggregate and cement paste; modified zirconia sol grafted with polyethylene glycol monomethyl ether forms steric hindrance, hindering OH- - Erosion of waste magnesium-calcium bricks and reduction of the effects of a highly alkaline environment on carboxylic acid groups and Ca 2+ The coordination effect, and the hydrophilic flexibility provided by polyethylene glycol monomethyl ether, further enhance the compatibility between aggregates and cementitious matrices.

[0033] 2. Room temperature spraying maintenance and low temperature working stage, fluorinated polyphosphazene and modified zirconia sol play a role in blocking moisture and OH - intrusion, carboxyethyl silane triol and polyethylene glycol monomethyl ether improve the compatibility and bonding force of the sprayed material, realize good workability and initial bonding strength, as the temperature rises to the medium temperature stage, fluorinated polyphosphazene, carboxyethyl silane triol and polyethylene glycol monomethyl ether begin to decompose, aluminum dihydrogen phosphate forms a viscous liquid phase to wrap the aggregate, providing temporary protection, as the temperature continues to rise, zirconia, nano Al2O3 and CaO and MgO react to form CaZrO3, MgAl2O3, realizing the protection of the sprayed material at different working temperatures.

[0034] 3. Aluminum dihydrogen phosphate can provide H + neutralize OH - generated by hydration, and aluminum dihydrogen phosphate can react with nano Al2O3 in the system at high temperature to form AlPO4, which can promote the liquid phase sintering between nano Al2O3 particles at high temperature, at the same time, AlPO4, CaZrO3, MgAl2O3 form a multiphase refractory structure, further improving the refractory performance of the refractory material. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 The refractory material containing waste and old magnesium-calcium bricks prepared by the application. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0037] Embodiment 1: The embodiment discloses a refractory material containing waste and old magnesium-calcium bricks, which comprises the following components in parts by weight: composite aggregate 58 parts, calcium aluminate cement 20 parts, urea-formaldehyde resin-aluminum dihydrogen phosphate 3.5 parts, active alpha-Al2O3 micropowder 7.5 parts, silicon micropowder 4 parts, and sodium tripolyphosphate 0.2 parts.

[0038] The carboxyethyl silane triol is used to anchor the waste and old magnesium-calcium bricks, then fluorinated polyphosphazene is grafted to form a hydrophobic protective layer, then the modified zirconia sol is used to wrap, and finally nano Al2O3 is introduced.

[0039] The modified zirconia sol is grafted with polyethylene glycol monomethyl ether.

[0040] The composite aggregate comprises the following components in parts by weight: 100 parts of waste magnesium-calcium brick, 3 parts of carboxyethyl silane triol, 5 parts of fluorinated polyphosphazene, 8 parts of modified zirconia sol, and 5 parts of nano-Al2O3.

[0041] The preparation method of the modified zirconia sol comprises the following steps:

[0042] S11. 16 g of zirconium hydroxide is dissolved in 100 mL of anhydrous ethanol, heated in a water bath at 40-50°C, continuously stirred, 5 mL of an acetylacetone ethanol solution is added, an ethanol solution of triethylamine is added dropwise, the pH is adjusted to 8-10, and the reaction is continuously stirred at 50-60°C to obtain a zirconia sol;

[0043] S12. 20 g of polyethylene glycol monomethyl ether and 4 mL of γ-(methacryloyloxy)propyltrimethoxysilane are mixed and dissolved in 60 mL of anhydrous ethanol, 0.22 g of organotin is added as a catalyst, and reflux reaction is carried out at 78-80°C for 4-6 h to obtain an activated polyethylene glycol monomethyl ether solution;

[0044] S13. The activated polyethylene glycol monomethyl ether solution is slowly added dropwise to the zirconia sol under stirring, and the reaction is continuously stirred at 50-70°C for 8-12 h, the obtained reaction liquid is sealed and placed at room temperature for 24-48 h, and rotary evaporation is carried out to obtain the modified zirconia sol.

[0045] The mass ratio of the polyethylene glycol monomethyl ether to the zirconium hydroxide is 1.25:1.

[0046] The preparation method of the composite aggregate comprises the following steps:

[0047] S21. 500 g of waste magnesium-calcium brick is crushed and sieved, washed repeatedly with deionized water and ethanol for 2-3 times, immersed in 1500 mL of 3% dilute phosphoric acid for 10-15 min, washed with deionized water, and dried in an oven at 110°C to obtain the aggregate;

[0048] S22. 5 g of carboxyethyl silane triol is added to 250 mL of an ethanol / deionized water mixed solvent, the pH is adjusted to 4-5 with dilute acetic acid, hydrolysis is carried out at room temperature for 30-60 min, the aggregate is immersed for 30-60 min, filtration is carried out, and solidification is carried out at 80-120°C for 30-60 min to obtain a first compound;

[0049] S23. 10 g of fluorinated polyphosphazene is added to 100 mL of an ethanol / acetone mixed solvent, heated in a water bath at 40°C, and dissolved by stirring to obtain a fluorinated polyphosphazene solution, the first compound is added to a fluidized bed, and is sprayed by atomization with the fluorinated polyphosphazene solution to obtain a second compound;

[0050] S24. 50g modified zirconia sol is diluted with deionized water to a solid content of 10%, 0.1g sodium hexametaphosphate is added to obtain a diluted modified zirconia sol, the second compound is placed in a roller, the diluted modified zirconia sol is sprayed, and the mixture is left to stand at room temperature for 24h, and is heat treated at 130-150 DEG C to solidify, thereby obtaining a third compound;

[0051] S25. 0.1g sodium hexametaphosphate is dissolved in 200mL deionized water, 10g nano-Al2O3 is ultrasonically dispersed, and stirring is continued to obtain a nano-Al2O3 dispersion liquid, the third compound is added, and stirring and impregnation are carried out for 30min, and the mixture is filtered and dried to obtain a composite aggregate.

[0052] The aggregate contains three particle sizes of 0.5-1mm, 1-3mm and 3-5mm, and the mass ratio is 2:5:3.

[0053] The preparation method of the urea-formaldehyde resin-aluminum dihydrogen phosphate comprises the following steps:

[0054] S31. 25g urea, 60mL 37% formaldehyde solution and 20mL deionized water are mixed, triethanolamine is used to adjust the pH to 8-9, and stirring is carried out at 70-75 DEG C for 1-2h to obtain a urea-formaldehyde resin prepolymer solution;

[0055] S32. 30g aluminum dihydrogen phosphate is dispersed in 100mL deionized water, 0.3g sodium dodecyl sulfate is added, and stirring is carried out until uniform to obtain a suspension;

[0056] S33. The suspension is poured into the urea-formaldehyde resin prepolymer solution, stirring is continuously carried out, dilute hydrochloric acid is added to adjust the pH to 2-4, and continuous reaction is carried out at 50-60 DEG C for 2-3h, the reaction liquid obtained is adjusted to neutral pH with a sodium hydroxide solution, filtration is carried out, washing is carried out with deionized water and ethanol, and vacuum drying is carried out at 50-60 DEG C to obtain a urea-formaldehyde resin-aluminum dihydrogen phosphate.

[0057] A preparation method of a refractory material containing waste and old magnesium-calcium bricks, comprising the following steps:

[0058] S1. The composite aggregate is placed in a mixer, active alpha-Al2O3 micropowder and silicon micropowder are added, low-speed stirring is carried out until uniform, calcium aluminate cement is slowly added, medium-speed stirring is carried out until uniform, sodium tripolyphosphate and urea-formaldehyde resin-aluminum dihydrogen phosphate are continuously added, and continuous stirring is carried out, and the mixture obtained is sieved to obtain a refractory material.

[0059] It should be noted that, as Figure 1 The refractory material prepared by the method can be mixed with water to prepare a gunning material for an electric furnace or a refining furnace.

[0060] Example 2: The example is based on example 1, and different from example 1, the refractory material containing waste magnesium calcium brick of the example comprises the following components in parts by weight: composite aggregate 50 parts, calcium aluminate cement 15 parts, aluminum dihydrogen phosphate 2 parts, active α-Al2O3 micropowder 5 parts, silicon micropowder 3 parts, sodium tripolyphosphate 0.1 part.

[0061] Other components and preparation methods are the same as example 1.

[0062] Example 3: The example is based on example 1, and different from example 1, the example discloses composite aggregate 65 parts, calcium aluminate cement 25 parts, aluminum dihydrogen phosphate 5 parts, active α-Al2O3 micropowder 10 parts, silicon micropowder 5 parts, sodium tripolyphosphate 0.3 part.

[0063] Other components and preparation methods are the same as example 1.

[0064] Example 4: The example is based on example 1, and different from example 1, the composite aggregate of the example comprises the following components in parts by weight: waste magnesium calcium brick 80 parts, carboxyethyl silane triol 2 parts, fluorinated polyphosphazene 3 parts, modified zirconia sol 5 parts, nano Al2O3 3 parts.

[0065] Other components and preparation methods are the same as example 1.

[0066] Example 5: The example is based on example 1, and different from example 1, the composite aggregate of the example comprises the following components in parts by weight: waste magnesium calcium brick 90 parts, carboxyethyl silane triol 2.5 parts, fluorinated polyphosphazene 4 parts, modified zirconia sol 6.5 parts, nano Al2O3 4 parts.

[0067] Other components and preparation methods are the same as example 1.

[0068] Example 6: The example is based on example 1, and different from example 1, the mass ratio of polyethylene glycol monomethyl ether to zirconium hydroxide of the example is 1:1.

[0069] Other components and preparation methods are the same as example 1.

[0070] Comparative example 1: The comparative example is based on example 1, and different from example 1, the modified zirconia sol of the comparative example is not grafted with polyethylene glycol monomethyl ether.

[0071] Other components and preparation methods are the same as example 1.

[0072] Comparative example 2: The comparative example is based on example 1, and different from example 1, the composite aggregate of the comparative example does not add carboxyethyl silane triol.

[0073] The preparation method of the composite aggregate comprises the following steps:

[0074] S21. 500g of waste magnesium-calcium bricks are crushed, sieved, washed repeatedly 2-3 times with deionized water and ethanol, soaked in 1500mL of 3% dilute phosphoric acid for 10-15min, washed with deionized water, and dried in an oven at 110°C to obtain the aggregate;

[0075] S22. 10g of fluorinated polyphosphazene is added to 100mL of an ethanol / acetone mixed solvent, heated in a 40°C water bath, and stirred to dissolve, to obtain a fluorinated polyphosphazene solution, the aggregate is added to a fluidized bed, and the fluorinated polyphosphazene solution is atomized and sprayed to obtain a fourth compound;

[0076] S23. 50g of modified zirconia sol is diluted with deionized water to a solid content of 10%, 0.1g of sodium hexametaphosphate is added to obtain diluted modified zirconia sol, the fourth compound is placed in a roller, the diluted modified zirconia sol is sprayed, and the mixture is left to stand at room temperature for 24h, and then heat-treated and solidified at 130-150°C to obtain a fifth compound;

[0077] S24. 0.1g of sodium hexametaphosphate is dissolved in deionized water, 10g of nano-Al2O3 is ultrasonically dispersed, and stirring is continued to obtain a nano-Al2O3 dispersion liquid, the fifth compound is added, stirring and soaking are performed for 30min, and then filtration and drying are performed to obtain a composite aggregate.

[0078] The other components and the preparation method are the same as in Example 1.

[0079] Comparative Example 3: This comparative example is based on Example 1, except that the composite aggregate of this comparative example does not add fluorinated polyphosphazene.

[0080] The preparation method of the composite aggregate comprises the following steps:

[0081] S21. 500g of waste magnesium-calcium bricks are crushed, sieved, washed repeatedly 2-3 times with deionized water and ethanol, soaked in 1500mL of 3% dilute phosphoric acid for 10-15min, washed with deionized water, and dried in an oven at 110°C to obtain the aggregate;

[0082] S22. 5g of carboxyethyl silane triol is added to 250mL of an ethanol / deionized water mixed solvent, the pH is adjusted to 4-5 with dilute acetic acid, and stirring is performed at room temperature for 30-60min, the aggregate is soaked for 30-60min, filtration is performed, and solidification is performed at 80-120°C for 30-60min to obtain a first compound;

[0083] S23. 50 g of the modified zirconia sol was diluted with deionized water to a solid content of 10%, 0.1 g of sodium hexametaphosphate was added to obtain a diluted modified zirconia sol, the first compound was placed in a roller, the diluted modified zirconia sol was sprayed, and the roller was left to stand at room temperature for 24 h, and was heat treated and solidified at 130-150 °C to obtain a sixth compound;

[0084] S24. 0.1 g of sodium hexametaphosphate was dissolved in 200 mL of deionized water, 10 g of nano-Al2O3 was ultrasonically dispersed, and stirring was continued to obtain a nano-Al2O3 dispersion liquid, the sixth compound was added, and stirring and impregnation were carried out for 30 min, and the mixture was filtered and dried to obtain a composite aggregate.

[0085] The other components and preparation methods were the same as in Example 1.

[0086] Comparative Example 4: The comparative example was based on Example 1, and different from Example 1 was that the composite aggregate described in the comparative example did not add a modified zirconia sol.

[0087] The preparation method of the composite aggregate comprises the following steps:

[0088] S21. 500 g of waste magnesium-calcium bricks were crushed and sieved, washed repeatedly with deionized water and ethanol for 2-3 times, immersed in 1500 mL of 3% dilute phosphoric acid for 10-15 min, washed with deionized water, and dried in an oven at 110 °C to obtain an aggregate;

[0089] S22. 5 g of carboxyethyl silane triol was added to 250 mL of an ethanol / deionized water mixed solvent, the pH was adjusted to 4-5 with dilute acetic acid, and stirring hydrolysis was carried out at room temperature for 30-60 min, the aggregate was added and impregnated for 30-60 min, and the mixture was filtered and solidified at 80-120 °C for 30-60 min to obtain a first compound;

[0090] S23. 10 g of fluorinated polyphosphazene was added to 100 mL of an ethanol / acetone mixed solvent, and stirring dissolution was carried out in a 40 °C water bath to obtain a fluorinated polyphosphazene solution, the first compound was added to a fluidized bed, and atomized spraying was carried out with the fluorinated polyphosphazene solution to obtain a second compound;

[0091] S24. 0.1 g of sodium hexametaphosphate was dissolved in 200 mL of deionized water, 10 g of nano-Al2O3 was ultrasonically dispersed, and stirring was continued to obtain a nano-Al2O3 dispersion liquid, the second compound was added, and stirring and impregnation were carried out for 30 min, and the mixture was filtered and dried to obtain a composite aggregate.

[0092] The other components and preparation methods were the same as in Example 1.

[0093] Comparative Example 5: The comparative example was based on Example 1, and different from Example 1 was that the composite aggregate described in the comparative example did not add nano-Al2O3.

[0094] The preparation method of the composite aggregate comprises the following steps:

[0095] S21. 500 g of waste magnesium-calcium bricks are crushed, sieved, washed repeatedly 2-3 times with deionized water and ethanol, soaked in 1500 mL of 3% dilute phosphoric acid for 10-15 min, washed with deionized water, and dried in an oven at 110°C to obtain the aggregate;

[0096] S22. 5 g of carboxyethyl silane triol is added to 250 mL of an ethanol / deionized water mixed solvent, the pH is adjusted to 4-5 with dilute acetic acid, hydrolysis is carried out at room temperature for 30-60 min, the aggregate is soaked for 30-60 min, filtration is performed, and solidification is carried out at 80-120°C for 30-60 min to obtain a first compound;

[0097] S23. 10 g of fluorinated polyphosphazene is added to 100 mL of an ethanol / acetone mixed solvent, stirring and dissolution are carried out in a 40°C water bath to obtain a fluorinated polyphosphazene solution, the first compound is placed in a fluidized bed, and spraying is carried out with the fluorinated polyphosphazene solution to obtain a second compound;

[0098] S24. 50 g of modified zirconia sol is diluted with deionized water to a solid content of 10%, 0.1 g of sodium hexametaphosphate is added to obtain diluted modified zirconia sol, the second compound is placed in a roller, the diluted modified zirconia sol is sprayed, and the mixture is left to stand at room temperature for 24 h, and heat treatment and solidification are carried out at 130-150°C to obtain a composite aggregate.

[0099] The other components and the preparation method are the same as in Example 1.

[0100] Comparative Example 6: This comparative example is based on Example 1, and is different from Example 1 in that the urea-formaldehyde resin-aluminum dihydrogen phosphate in this comparative example does not contain urea-formaldehyde resin.

[0101] The other components and the preparation method are the same as in Example 1.

[0102] Since aluminum dihydrogen phosphate will undergo a violent and rapid acid-base neutralization reaction when it comes into contact with calcium aluminate cement in the presence of water, resulting in instantaneous solidification of the refractory material, which cannot be sprayed, it is necessary to wrap it with urea-formaldehyde resin, which gradually releases aluminum dihydrogen phosphate under the action of mechanical shear force and cement hydration heat.

[0103] Comparative Example 7: This comparative example is based on Example 1, and is different from Example 1 in that the urea-formaldehyde resin-aluminum dihydrogen phosphate in this comparative example does not contain urea-formaldehyde resin.

[0104] The other components and the preparation method are the same as in Example 1.

[0105] Comparative Example 8: This comparative example is a blank control group. The comparative example discloses a refractory material containing waste magnesium-calcium brick, which comprises the following components in parts by weight: aggregate 58 parts, calcium aluminate cement 20 parts, active a-Al2O3 micro powder 7.5 parts, silicon micro powder 4 parts, and sodium tripolyphosphate 0.2 parts.

[0106] A preparation method of a refractory material containing waste magnesium-calcium brick, comprising the following steps:

[0107] S1. The waste magnesium-calcium brick is crushed, sieved, washed repeatedly with deionized water and ethanol, and dried in an oven to obtain an aggregate;

[0108] S2. The aggregate is placed in a mixer, active a-Al2O3 micro powder and silicon micro powder are added, and low-speed stirring is performed to mix uniformly. Calcium aluminate cement is slowly added, and medium-speed stirring is performed to mix uniformly. Sodium tripolyphosphate is continuously added, and stirring is continued. The obtained mixture is sieved to obtain the refractory material.

[0109] Test verification:

[0110] Test one: performance verification of composite aggregate

[0111] (1) Hydrophobicity: The composite aggregate prepared in Example 1 and Comparative Examples 1-7 is pressed into a flat and smooth sheet. A microsyringe is used to drop about 5 μL of ultrapure water on the surface of the sample. The contact angle is measured and recorded in real time by the instrument software. The waste magnesium-calcium brick without treatment is used as Control Group 1.

[0112] (2) Alkali resistance: The composite aggregate prepared in Example 1 and Comparative Examples 1-7 is soaked in a NaOH solution, and the reaction is accelerated in a constant-temperature water bath at 40°C. After 1 day, 3 days, and 7 days, respectively, the sample is taken out, washed, dried, weighed, and the mass change rate is calculated. The waste magnesium-calcium brick without treatment is used as Control Group 1.

[0113] (3) Compatibility with cement: The composite aggregate prepared in Example 1 and Comparative Examples 1-7 is manually mixed with cement paste. It is observed whether the aggregate is floating, agglomerating, or uniformly dispersed. The waste magnesium-calcium brick without treatment is used as Control Group 1.

[0114] (4) The refractory material prepared in Example 1 and Comparative Examples 1-7 is mixed with water to prepare a sample with dimensions of 40x40x160mm. The sample is standard cured for 24h, dried at 110°C, and its room temperature bending strength is measured.

[0115]

[0116] The basic properties of the composite aggregate are shown in Table 1. From the data in the table, the strong hydrophobic property of fluorinated polyphosphazene effectively prevents water from invading, the modified zirconia sol and urea-formaldehyde resin-aluminum dihydrogen phosphate can resist the influence of high alkalinity of cement hydration on the composite aggregate, the carboxyethyl silane triol and polyethylene glycol monomethyl ether carboxylic acid group improve the compatibility and wettability of the composite aggregate with the cement slurry, and the interfacial bonding strength between the aggregate and the cement is significantly improved.

[0117] Test two: basic properties of refractory materials

[0118] (1) High temperature stability: the refractory materials prepared in the examples and comparative examples were mixed with water to prepare samples of 40x40x160mm, standard curing for 24 hours, drying at 110°C for 24h, the dried samples were placed in a high temperature furnace, heated to the target temperature at a rate of 5°C / min: 400°C, 800°C, 1400°C, after reaching the target temperature, the temperature was kept for 3 hours, and the furnace was cooled to room temperature, then the flexural strength was measured on a universal testing machine, compared with the flexural strength before treatment, and the flexural strength retention rate was calculated.

[0119] (2) Long-term durability: the refractory materials prepared in the examples and comparative examples were mixed with water to prepare samples of 40x40x160mm, standard curing for 24 hours, drying at 110°C for 24h, the samples were placed in an autoclave, treated at 120°C under saturated steam pressure for 3h, the samples were taken out to observe whether they were cracked or powdered, the flexural strength after treatment was measured, compared with the flexural strength before treatment, and the flexural strength retention rate was calculated.

[0120]

[0121] The basic properties of the refractory materials are shown in Table 2. From the data in the table, at 400°C, the organic matter begins to decompose, at this time the viscous liquid phase formed by aluminum dihydrogen phosphate plays a bonding role, preventing a sharp drop in strength, at 800°C, the organic matter is completely decomposed, at this time the strength is at a minimum, as the temperature rises to 1400°C, AlPO4, CaZrO3, MgAl2O3 are successively generated, forming a multiphase refractory structure, further improving the flexural strength of the refractory material. In the durability test of the material, it can be seen that the composite protective layer of fluorinated polyphosphazene and modified zirconia sol can effectively resist the erosion of high temperature and high pressure water vapor, and the material has excellent hydration resistance.

[0122] The above description is only the preferred embodiment of the present application, and is not intended to limit the protection scope of the present application, any modification, equivalent replacement and improvement made by any person skilled in the art within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A refractory material containing waste magnesia-calcium bricks, characterized in that, The composition includes the following components in parts by weight: 50-65 parts composite aggregate, 15-25 parts calcium aluminate cement, 2-5 parts urea-formaldehyde resin-aluminum dihydrogen phosphate, 5-10 parts active α-Al2O3 micro powder, 3-5 parts silica micro powder, and 0.1-0.3 parts sodium tripolyphosphate. The composite aggregate is anchored with carboxyethylsilane triol to waste magnesium-calcium bricks and then grafted with fluorinated polyphosphazene to form a hydrophobic protective layer, then coated with modified zirconium oxide sol, and finally introduced with nano-Al2O3. The modified zirconium oxide sol grafted with polyethylene glycol monomethyl ether; The preparation method of the urea-formaldehyde resin-aluminum dihydrogen phosphate includes the following steps: S31. Mix urea, formaldehyde solution and deionized water, adjust the pH with triethanolamine, stir the reaction to obtain urea-formaldehyde resin prepolymer solution; S32. Disperse aluminum dihydrogen phosphate in deionized water, add sodium dodecyl sulfate, stir until homogeneous, and obtain a suspension; S33. Pour the suspension into the urea-formaldehyde resin prepolymer solution, add dilute hydrochloric acid to adjust the pH while stirring continuously, and continue the reaction. Adjust the pH of the resulting reaction solution to neutral with sodium hydroxide solution, filter, wash with deionized water and ethanol, and vacuum dry to obtain urea-formaldehyde resin-aluminum dihydrogen phosphate.

2. The refractory material containing waste magnesia-calcium bricks according to claim 1, characterized in that, The composite aggregate comprises the following components in parts by weight: 80-100 parts of waste magnesium-calcium bricks, 2-3 parts of carboxyethylsilane triol, 3-5 parts of fluorinated polyphosphazene, 5-8 parts of modified zirconium oxide sol, and 3-5 parts of nano-Al2O3.

3. The refractory material containing waste magnesia-calcium bricks according to claim 2, characterized in that, The preparation method of the modified zirconia sol includes the following steps: S11. Dissolve zirconium hydroxide in anhydrous ethanol, heat in a water bath, stir continuously, add acetylacetone ethanol solution, add triethylamine ethanol solution dropwise, adjust pH to 8-10, continue stirring to react, and obtain zirconium oxide sol. S12. Polyethylene glycol monomethyl ether and γ-(methacryloyloxy)propyltrimethoxysilane are mixed and dissolved in anhydrous ethanol, organotin is added as a catalyst, and the mixture is refluxed to obtain an activated polyethylene glycol monomethyl ether solution. S13. Under stirring, the activated polyethylene glycol monomethyl ether solution is slowly added dropwise to the zirconia sol, and the reaction is continuously stirred. The resulting reaction solution is sealed and allowed to stand at room temperature, and then concentrated by rotary evaporation to obtain the modified zirconia sol.

4. The refractory material containing waste magnesia-calcium bricks according to claim 3, characterized in that, The mass ratio of polyethylene glycol monomethyl ether to zirconium hydroxide is 1~1.25:

1.

5. A refractory material containing waste magnesia-calcium bricks according to claim 1, characterized in that, The method for preparing the composite aggregate includes the following steps: S21. The waste magnesium-calcium bricks are crushed and screened, washed repeatedly with deionized water and ethanol, impregnated in dilute phosphoric acid, washed with deionized water, and dried in an oven to obtain aggregates. S22. Carboxyethylsilanetriol was added to a mixed solvent of ethanol / deionized water, the pH was adjusted with dilute acetic acid, hydrolyzed by stirring at room temperature, impregnated with aggregate, filtered, and solidified to obtain the first compound; S23. Fluorinated polyphosphazene is added to an ethanol / acetone mixed solvent, heated in a water bath, and stirred to dissolve, thereby obtaining a fluorinated polyphosphazene solution. The first compound is added to a fluidized bed and sprayed with the fluorinated polyphosphazene solution by atomization to obtain the second compound. S24. Dilute the modified zirconia sol with deionized water to a solid content of 10%, add sodium hexametaphosphate to obtain diluted modified zirconia sol, place the second compound in a roller, spray the diluted modified zirconia sol, let it stand at room temperature, and heat-treat to cure to obtain the third compound. S25. Dissolve sodium hexametaphosphate in deionized water, add nano-Al2O3 and disperse ultrasonically, continue stirring to obtain nano-Al2O3 dispersion, add third compound, stir and impregnate, filter and dry to obtain composite aggregate.

6. A refractory material containing waste magnesia-calcium bricks according to claim 5, characterized in that, The aggregate contains three particle sizes: 0.5-1 mm, 1-3 mm, and 3-5 mm, with a mass ratio of 2:5:

3.

7. A method for preparing a refractory material containing waste magnesia-calcium bricks, applied to the preparation of a refractory material containing waste magnesia-calcium bricks as described in any one of claims 1 to 6, characterized in that, The method includes the following steps: S1. Place the composite aggregate in a mixer, add active α-Al2O3 micro powder and silica micro powder, stir at low speed to mix evenly, slowly add calcium aluminate cement, stir at medium speed to mix evenly, continue to add sodium tripolyphosphate and urea-formaldehyde resin-aluminum dihydrogen phosphate, continue stirring, and sieve the resulting mixture to obtain refractory material.

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