Refractory material containing waste magnesia-calcium bricks and preparation method thereof

Abstract

The invention relates to the technical field of refractory materials, in particular to a waste magnesia-calcium brick-containing refractory material and a preparation method thereof, and the waste magnesia-calcium brick-containing refractory material comprises the following components: composite aggregate, calcium aluminate cement, urea resin-aluminum dihydrogen phosphate, active alpha-Al2O3 micro powder, silica micro powder and sodium tripolyphosphate. In the room-temperature spraying maintenance and low-temperature working stage, hydration of free CaO in the waste magnesia-calcium bricks and erosion of OH <-> are prevented through the hydrophobic effect of fluorinated polyphosphazene and modified zirconium oxide sol, and the compatibility and wettability of the composite aggregate and cement paste are improved through carboxylic acid groups of carboxyethyl silanetriol and polyethylene glycol monomethyl ether. According to the present invention, with the temperature rising, the aluminum dihydrogen phosphate forms the viscous liquid phase to wrap the aggregate so as to provide the temporary protection, the temperature continues to rise, the zirconium oxide and the nanometer Al2O3 react with the CaO and the MgO to generate the CaZrO3 and the MgAl2O3, the aluminum dihydrogen phosphate reacts with the nanometer Al2O3 in the system to generate the AlPO4, and the CaZrO3, the MgAl2O3 and the AlPO4 form the multi-phase fire-resistant structure so as to further improve the fire resistance of the fire-resistant 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, the free CaO will be severely hydrated when water is encountered, so that the spray coating material is invalid, and therefore, 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, so that the spray adhesion rate is low and the spray coating is easy to fall off. The inorganic wrapping layer is often brittle and is easy to produce cracks under the impact of construction. SUMMARY

[0003] (1) Technical problem to be solved The purpose of the 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 be reduced and the adhesion rate to be low when the waste magnesium-calcium bricks are wrapped to resist hydration.

[0004] (2) Technical scheme To achieve the above-mentioned purpose, on the one hand, the 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. The composite aggregate anchors the waste magnesium-calcium bricks by using carboxyethyl silane triol, grafts fluorinated polyphosphazene to form a hydrophobic protective layer, is wrapped by using modified zirconia sol, and finally introduces nano-Al2O3. The modified zirconia sol is grafted with polyethylene glycol monomethyl ether.

[0005] 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.

[0006] Further, the preparation method of the modified zirconia sol comprises the following steps: S11. Zirconium hydroxide is dissolved in anhydrous ethanol, heated in a water bath, continuously stirred, an acetylacetone ethanol solution is added, an ethanol solution of triethylamine is added dropwise, the pH is adjusted to 8-10, and the stirring reaction is continued to obtain zirconia sol. S12. Polyethylene glycol monomethyl ether and gamma-(methacryloyloxy) propyl trimethoxysilane are mixed and dissolved in anhydrous ethanol, and organic tin is added as a catalyst to reflux and react to obtain an activated polyethylene glycol monomethyl ether solution; S13. The activated polyethylene glycol monomethyl ether solution is slowly added to the zirconium oxide sol under stirring, and the reaction is continuously stirred to obtain a reaction solution which is sealed and placed at room temperature, concentrated by rotary evaporation to obtain a modified zirconium oxide sol.

[0007] Further, the mass ratio of the polyethylene glycol monomethyl ether to the zirconium hydroxide is 1-1.25:1.

[0008] Further, the preparation method of the composite aggregate comprises the following steps: S21. The waste magnesium-calcium brick is crushed, sieved, washed repeatedly with deionized water and ethanol, immersed in dilute phosphoric acid, washed with deionized water, and dried in an oven to obtain an aggregate; S22. Carboxyethyl silane triol is added to an ethanol / deionized water mixed solvent, the pH is adjusted with dilute acetic acid, hydrolysis is performed under stirring at room temperature, the aggregate is immersed, filtered, and solidified to obtain a first compound; S23. Fluorinated polyphosphazene is added to an ethanol / acetone mixed solvent, dissolved by heating in a water bath and stirring to obtain a fluorinated polyphosphazene solution, the first compound is added to a fluidized bed, and the fluorinated polyphosphazene solution is atomized and sprayed to obtain a second compound; S24. The modified zirconium oxide sol is diluted with deionized water to a solid content of 10%, sodium hexametaphosphate is added to obtain a diluted modified zirconium oxide sol, the second compound is placed in a drum, the diluted modified zirconium oxide sol is sprayed, and the third compound is obtained by standing at room temperature and heat treatment and solidification; S25. Sodium hexametaphosphate is dissolved in deionized water, nano-Al2O3 is ultrasonically dispersed, stirring is continued, a nano-Al2O3 dispersion liquid is obtained, the third compound is added, immersed and stirred, filtered and dried to obtain a composite aggregate.

[0009] Further, the aggregate contains three particle sizes of 0.5-1 mm, 1-3 mm, and 3-5 mm, and the mass ratio is 2:5:3.

[0010] Further, the preparation method of the urea-formaldehyde resin-aluminum dihydrogen phosphate comprises the following steps: S31. Urea, formaldehyde solution, and deionized water are mixed, the pH is adjusted with triethanolamine, and the reaction is stirred to obtain a urea-formaldehyde resin prepolymer solution; S32. Aluminum dihydrogen phosphate is dispersed in deionized water, sodium dodecyl sulfate is added, and stirring is performed until uniform to obtain a suspension; S33. Pour the suspension into the urea-formaldehyde resin prepolymer solution, continuously stirring, adjust the pH with dilute hydrochloric acid, continue the reaction, the obtained reaction solution is adjusted to neutral pH with sodium hydroxide solution, filtered, washed with deionized water and ethanol, vacuum dried to obtain urea-formaldehyde resin-aluminum dihydrogen phosphate.

[0011] In another aspect, based on the same inventive concept, the application also 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 comprises the following steps: S1. Put the composite aggregate into a mixer, add active alpha-Al2O3 micro powder and silicon 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, continuously stir, sieve the obtained mixture to obtain the refractory material.

[0012] 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, leading to difficult construction and the decline of the high-temperature volume stability and strength of the refractory material, the waste magnesium-calcium bricks need to be wrapped with hydrophobic fluorinated polyphosphazene to form a dense physical barrier to prevent hydration. However, due to its high hydrophobicity, the compatibility and binding 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 react with Ca 2+ to form stable calcium carboxylate complexes, and the hydrophilicity of the carboxylic acid groups is improved to improve the compatibility and wettability with the cement paste.

[0013] The strong alkaline environment caused by the hydration of 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 - produced by hydration, and the product can seal the pores of the refractory material, and its accelerating effect is beneficial to spraying. On the other hand, zirconia itself has low reactivity with OH - and can remain stable for a long time, and the grafted polyethylene glycol monomethyl ether forms steric hindrance, further hindering the erosion of OH - to the waste magnesium-calcium bricks and reducing the strong alkaline environment to the carboxylic acid groups and Ca 2+The coordination effect. At the same time, the modified zirconia sol grafted with polyethylene glycol monomethyl ether provides hydrophilic softness, further enhances the compatibility of the aggregate and the cement matrix, and the flexibility of the long chain of polyethylene glycol monomethyl ether acts as a stress buffer layer to absorb the internal stress generated at the interface due to the shrinkage of cement hydration, preventing interface cracking and thus enhancing the bonding force.

[0014] Since the above fluorinated polyphosphazene and polyethylene glycol monomethyl ether will decompose at the temperature at which the refractory material is used as a gunning material, nano-Al2O3 is introduced into the aggregate, and at room temperature, the fluorinated polyphosphazene and the modified zirconia sol are used to block moisture and OH - intrusion, and the carboxyethyl silane triol and the polyethylene glycol monomethyl ether improve the compatibility and bonding force of the gunning material, achieving good workability and initial bonding strength. As the working temperature increases, the fluorinated polyphosphazene, the carboxyethyl silane triol, and the polyethylene glycol monomethyl ether begin to decompose, at which time the added aluminum dihydrogen phosphate forms a viscous liquid phase to wrap the aggregate, providing temporary protection. As the temperature continues to rise, the zirconia reacts with CaO to form a CaZrO3 stable phase, and the added nano-Al2O3 reacts with the MgO on the surface of the aggregate to form MgAl2O3, generating a continuous, dense, and high-refractory sintered layer in situ. The aluminum dihydrogen phosphate can react with the nano-Al2O3, MgO, etc. in the system at high temperatures to generate high-temperature stable phases such as AlPO4 and magnesium aluminum phosphate. AlPO4 can promote liquid phase sintering between nano-Al2O3 particles at high temperatures, thereby improving the bending strength of the material. At the same time, CaZrO3, MgAl2O3, and AlPO4 form a multiphase refractory structure, further improving the refractory performance of the refractory material.

[0015] In summary, due to the adoption of the above technical solutions, the present application has the following advantages: 1. The hydrophobic effect of fluorinated polyphosphazene prevents the hydration of free CaO in waste and old magnesium calcium bricks, the carboxylic acid groups of carboxyethyl silane triol improve the compatibility and wettability of the composite aggregate and the cement paste, the modified zirconia sol grafted with polyethylene glycol monomethyl ether forms steric hindrance to hinder the erosion of waste and old magnesium calcium bricks and reduce the effect of the strong alkaline environment on the carboxylic acid groups and Ca - 2+ coordination effect, and the polyethylene glycol monomethyl ether provides hydrophilic softness, further enhancing the compatibility of the aggregate and the cement matrix.

[0016] 2. At room temperature, the fluorinated polyphosphazene and the modified zirconia sol are used to block 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, with the temperature rising 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, and with the temperature continuing to rise, zirconia, nano Al2O3 and CaO and MgO react to form CaZrO3 and MgAl2O3, realizing the protection of the sprayed material at different working temperatures.

[0017] 3. Aluminum dihydrogen phosphate can provide H + Neutralize the 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, and at the same time, AlPO4, CaZrO3 and MgAl2O3 form a multiphase refractory structure, further improving the refractory performance of the refractory material. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The refractory material containing waste and old magnesium-calcium bricks prepared by the present application. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present application will be described clearly and completely below in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0020] Embodiment 1: The present 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. The composite aggregate anchors the waste and old magnesium-calcium bricks with carboxyethyl silane triol, grafts fluorinated polyphosphazene to form a hydrophobic protective layer, is wrapped with modified zirconia sol, and finally introduces nano Al2O3. The modified zirconia sol is grafted with polyethylene glycol monomethyl ether.

[0021] The composite aggregate comprises the following components in parts by weight: waste and old magnesium-calcium bricks 100 parts, carboxyethyl silane triol 3 parts, fluorinated polyphosphazene 5 parts, modified zirconia sol 8 parts, and nano Al2O3 5 parts.

[0022] The preparation method of the modified zirconia sol comprises the following steps: S11. 16 g of zirconium hydroxide was dissolved in 100 mL of anhydrous ethanol, heated in a water bath at 40-50℃, continuously stirred, 5 mL of acetylacetone ethanol solution was added, triethylamine ethanol solution was added dropwise, the pH was adjusted to 8-10, and the reaction was continued to stir at 50-60℃, to obtain a zirconium oxide sol; S12. 20 g of polyethylene glycol monomethyl ether and 4 mL of γ-(methacryloyloxy) propyl trimethoxysilane were mixed and dissolved in 60 mL of anhydrous ethanol, 0.22 g of organotin was added as a catalyst, and the reaction was carried out at 78-80℃ for 4-6 h to obtain an activated polyethylene glycol monomethyl ether solution; S13. The activated polyethylene glycol monomethyl ether solution was slowly added dropwise to the zirconium oxide sol under stirring, and the reaction was continuously stirred at 50-70℃ for 8-12 h. The obtained reaction liquid was sealed and placed at room temperature for 24-48 h, concentrated by rotary evaporation, and a modified zirconium oxide sol was obtained.

[0023] The mass ratio of the polyethylene glycol monomethyl ether to the zirconium hydroxide is 1.25:1.

[0024] The preparation method of the composite aggregate comprises the following steps: S21. The 500 g of waste magnesium-calcium bricks were crushed, 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℃ to obtain the aggregate; 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, hydrolysis was carried out at room temperature for 30-60 min, the aggregate was immersed for 30-60 min, filtered, and cured at 80-120℃ for 30-60 min to obtain a first compound; S23. 10 g of fluorinated polyphosphazene was added to 100 mL of an ethanol / acetone mixed solvent, heated in a water bath at 40℃, and dissolved by stirring to obtain a fluorinated polyphosphazene solution. The first compound was placed in a fluidized bed and sprayed with the fluorinated polyphosphazene solution to obtain a second compound; S24. 50 g of the modified zirconium oxide 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 zirconium oxide sol, the second compound was placed in a roller, and the diluted modified zirconium oxide sol was sprayed. After being placed at room temperature for 24 h, heat treatment and curing were carried out at 130-150℃ to obtain a third compound; S25. 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 third compound was added, stirred and immersed for 30 min, filtered and dried to obtain a composite aggregate.

[0025] The aggregate contains three particle sizes of 0.5-1mm, 1-3mm, and 3-5mm, and the mass ratio is 2:5:3.

[0026] The preparation method of the urea-formaldehyde resin-aluminum dihydrogen phosphate comprises the following steps: S31. 25g of urea, 60mL of 37% formaldehyde solution, and 20mL of deionized water are mixed, the pH is adjusted to 8-9 with triethanolamine, and stirring reaction is carried out at 70-75℃ for 1-2h to obtain a urea-formaldehyde resin prepolymer solution; S32. 30g of aluminum dihydrogen phosphate is dispersed in 100mL of deionized water, 0.3g of sodium dodecyl sulfate is added, and stirring is uniformly carried out to obtain a suspension; 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, continuous reaction is carried out at 50-60℃ for 2-3h, the obtained reaction solution 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℃ to obtain the urea-formaldehyde resin-aluminum dihydrogen phosphate.

[0027] A preparation method of a refractory material containing waste magnesium-calcium bricks, comprising the following steps: S1. The composite aggregate is placed in a mixer, active alpha-Al2O3 micro powder and silicon micro powder are added, low-speed stirring is carried out to mix uniformly, calcium aluminate cement is slowly added, medium-speed stirring is carried out to mix uniformly, sodium tripolyphosphate and urea-formaldehyde resin-aluminum dihydrogen phosphate are continuously added, and continuous stirring is carried out, and the obtained mixture is sieved to obtain the refractory material.

[0028] It should be noted that, as Figure 1 The refractory material prepared by the application can be mixed with water to prepare a gunning material for an electric furnace or a refining furnace.

[0029] Example 2: This example is based on example 1, and different from example 1, the refractory material containing waste magnesium-calcium bricks in this example comprises the following components in parts by weight: composite aggregate 50 parts, calcium aluminate cement 15 parts, aluminum dihydrogen phosphate 2 parts, active alpha-Al2O3 micro powder 5 parts, silicon micro powder 3 parts, and sodium tripolyphosphate 0.1 part.

[0030] The other components and the preparation method are the same as those in example 1.

[0031] Example 3: This example is based on example 1, and different from example 1, the composite aggregate 65 parts, calcium aluminate cement 25 parts, aluminum dihydrogen phosphate 5 parts, active alpha-Al2O3 micro powder 10 parts, silicon micro powder 5 parts, and sodium tripolyphosphate 0.3 parts are disclosed.

[0032] The other components and the preparation method are the same as those in example 1.

[0033] Example 4: This example is based on example 1, except that the composite aggregate of this example comprises the following components in parts by weight: 80 parts of waste magnesium calcium brick, 2 parts of carboxyethyl silane triol, 3 parts of fluorinated polyphosphazene, 5 parts of modified zirconia sol, and 3 parts of nano-Al2O3.

[0034] The other components and preparation method are the same as in example 1.

[0035] Example 5: This example is based on example 1, except that the composite aggregate of this example comprises the following components in parts by weight: 90 parts of waste magnesium calcium brick, 2.5 parts of carboxyethyl silane triol, 4 parts of fluorinated polyphosphazene, 6.5 parts of modified zirconia sol, and 4 parts of nano-Al2O3.

[0036] The other components and preparation method are the same as in example 1.

[0037] Example 6: This example is based on example 1, except that the mass ratio of polyethylene glycol monomethyl ether to zirconium hydroxide in this example is 1:1.

[0038] The other components and preparation method are the same as in example 1.

[0039] Comparative example 1: This comparative example is based on example 1, except that the modified zirconia sol of this comparative example is not grafted with polyethylene glycol monomethyl ether.

[0040] The other components and preparation method are the same as in example 1.

[0041] Comparative example 2: This comparative example is based on example 1, except that the composite aggregate of this comparative example does not contain carboxyethyl silane triol.

[0042] The preparation method of the composite aggregate comprises the following steps: S21. 500g of waste magnesium calcium brick is 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; S22. 10g of fluorinated polyphosphazene is added to 100mL of 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 sprayed with the fluorinated polyphosphazene solution to obtain a fourth compound; S23. 50g of modified zirconia sol is diluted with deionized water to a solid content of 10%, and 0.1g of sodium hexametaphosphate is added to obtain a diluted modified zirconia sol. The fourth compound is placed in a roller and sprayed with the diluted modified zirconia sol. It is left to stand at room temperature for 24h and heat treated at 130-150°C to solidify to obtain a fifth compound. S24. 0.1 g sodium hexametaphosphate was dissolved in deionized water, 10 g nano-Al2O3 was ultrasonically dispersed, and stirring was continued to obtain a nano-Al2O3 dispersion liquid. The sixth compound was added, and stirring and immersion were performed for 30 min. Filtration and drying were performed to obtain a composite aggregate.

[0043] The other components and preparation methods were the same as in Example 1.

[0044] Comparative Example 3: The comparative example was based on Example 1, except that the composite aggregate described in the comparative example did not add fluorinated polyphosphazene.

[0045] The preparation method of the composite aggregate included the following steps: S21. 500 g of waste magnesium-calcium bricks were crushed and sieved, washed repeatedly 2-3 times with deionized water and ethanol, 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; S22. 5 g of carboxyethyl silane triol was added to 250 mL of an ethanol / deionized water mixed solvent, and the pH was adjusted to 4-5 with dilute acetic acid. Hydrolysis was performed at room temperature for 30-60 min with stirring. The aggregate was immersed for 30-60 min, and filtration and solidification at 80-120°C for 30-60 min were performed to obtain a first compound; S23. 50 g of modified zirconia sol was diluted with deionized water to a solid content of 10%, and 0.1 g of sodium hexametaphosphate was added to obtain diluted modified zirconia sol. The first compound was placed in a roller, and the diluted modified zirconia sol was sprayed. The mixture was allowed to stand at room temperature for 24 h, and heat treatment and solidification at 130-150°C were performed to obtain a sixth compound; S24. 0.1 g of sodium hexametaphosphate was dissolved in 200 mL of deionized water, and 10 g of nano-Al2O3 was ultrasonically dispersed. Stirring was continued to obtain a nano-Al2O3 dispersion liquid. The sixth compound was added, and stirring and immersion were performed for 30 min. Filtration and drying were performed to obtain a composite aggregate.

[0046] The other components and preparation methods were the same as in Example 1.

[0047] Comparative Example 4: The comparative example was based on Example 1, except that the composite aggregate described in the comparative example did not add modified zirconia sol.

[0048] The preparation method of the composite aggregate included the following steps: S21. 500 g of waste magnesium-calcium bricks were crushed and sieved, washed repeatedly 2-3 times with deionized water and ethanol, 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; S22. 5 g carboxyethyl silane triol was added into 250 mL ethanol / deionized water mixed solvent, and the pH was adjusted to 4-5 with dilute acetic acid. Hydrolysis was carried out at room temperature for 30-60 min. The aggregate was immersed for 30-60 min, filtered, and cured at 80-120 °C for 30-60 min to obtain a first compound; S23. 10 g fluorinated polyphosphazene was added into 100 mL ethanol / acetone mixed solvent, and dissolved by stirring under 40 °C water bath to obtain a fluorinated polyphosphazene solution. The first compound was added into a fluidized bed, and sprayed by the fluorinated polyphosphazene solution to obtain a second compound; S24. 0.1 g sodium hexametaphosphate was dissolved in 200 mL deionized water, and 10 g nano-Al2O3 was ultrasonically dispersed. The stirring was continued to obtain a nano-Al2O3 dispersion liquid. The second compound was added and immersed for 30 min. After filtration and drying, a composite aggregate was obtained.

[0049] The other components and preparation methods were the same as those in Example 1.

[0050] Comparative Example 5: The composite aggregate of the comparative example was prepared based on Example 1, except that the composite aggregate of the comparative example did not contain nano-Al2O3.

[0051] The preparation method of the composite aggregate comprises the following steps: S21. The waste magnesium-calcium brick was crushed and sieved. Deionized water and ethanol were repeatedly washed for 2-3 times. The aggregate was obtained by immersing in 1500 mL 3% dilute phosphoric acid for 10-15 min, washing with deionized water, and drying in an oven at 110 °C. S22. 5 g carboxyethyl silane triol was added into 250 mL ethanol / deionized water mixed solvent, and the pH was adjusted to 4-5 with dilute acetic acid. Hydrolysis was carried out at room temperature for 30-60 min. The aggregate was immersed for 30-60 min, filtered, and cured at 80-120 °C for 30-60 min to obtain a first compound; S23. 10 g fluorinated polyphosphazene was added into 100 mL ethanol / acetone mixed solvent, and dissolved by stirring under 40 °C water bath to obtain a fluorinated polyphosphazene solution. The first compound was added into a fluidized bed, and sprayed by the fluorinated polyphosphazene solution to obtain a second compound; S24. 0.1 g sodium hexametaphosphate was dissolved in 200 mL deionized water, and 10 g nano-Al2O3 was ultrasonically dispersed. The stirring was continued to obtain a nano-Al2O3 dispersion liquid. The second compound was added and immersed for 30 min. After filtration and drying, a composite aggregate was obtained.

[0052] The other components and preparation methods were the same as those in Example 1.

[0053] Comparative Example 6: This comparative example is based on Example 1, except that the urea-formaldehyde resin-aluminum dihydrogen phosphate in this comparative example does not contain urea-formaldehyde resin.

[0054] The other components and preparation methods are the same as in Example 1.

[0055] Because the aluminum dihydrogen phosphate will undergo a violent and rapid acid-base neutralization reaction once it comes into contact with the calcium aluminate cement in the presence of water, causing the refractory material to instantly solidify and be unable to be sprayed, it is therefore necessary to be wrapped with urea-formaldehyde resin, which gradually releases the aluminum dihydrogen phosphate under the action of mechanical shear force and cement hydration heat.

[0056] Comparative Example 7: This comparative example is based on Example 1, except that the urea-formaldehyde resin-aluminum dihydrogen phosphate in this comparative example does not contain urea-formaldehyde resin.

[0057] The other components and preparation methods are the same as in Example 1.

[0058] Comparative Example 8: This comparative example is a blank control group, and discloses a refractory material containing waste magnesium-calcium bricks, 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, silica micro powder 4 parts, and sodium tripolyphosphate 0.2 parts.

[0059] A preparation method of a refractory material containing waste magnesium-calcium bricks, comprising the following steps: S1. The waste magnesium-calcium bricks are crushed, sieved, washed repeatedly with deionized water and ethanol, and dried in an oven to obtain an aggregate; S2. The aggregate is placed in a mixer, active a-Al2O3 micro powder and silica micro powder are added, and stirred uniformly at low speed, calcium aluminate cement is slowly added, and stirred uniformly at medium speed, sodium tripolyphosphate is continuously added, and stirring is continued, and the obtained mixture is sieved to obtain the refractory material.

[0060] Test verification: Test 1: Performance verification of composite aggregate (1) Hydrophobicity: The composite aggregates prepared in Example 1 and Comparative Examples 1-7 are pressed into flat and smooth sheets, about 5 μL of ultrapure water is added dropwise on the surface of the sample using a microsyringe, the contact angle is measured and recorded in real time by the instrument software, and the waste magnesium-calcium bricks without treatment are used as a control group 1.

[0061] (2) Alkali resistance: The composite aggregates prepared in Example 1 and Comparative Examples 1-7 are soaked in a NaOH solution, and the reaction is accelerated in a constant-temperature water bath at 40°C, and then taken out after 1 day, 3 days, and 7 days, respectively, washed, dried, weighed, and the mass change rate is calculated, and the waste magnesium-calcium bricks without treatment are used as a control group 1.

[0062] (3) Compatibility with cement: The composite aggregates prepared in Example 1 and Comparative Examples 1-7 were mixed with cement paste by hand, and the aggregates were observed to be floating, agglomerating or uniformly dispersed, with waste magnesium-calcium bricks without treatment as a control group 1.

[0063] (4) The refractory materials prepared in Example 1 and Comparative Examples 1-7 were mixed with water, and samples of 40x40x160mm were prepared, standard curing for 24h, dried at 110°C, and the cold modulus of rupture was measured.

[0064]

[0065] As shown in Table 1, the basic properties of the composite aggregates were as follows: the strong hydrophobic properties of the fluorinated polyphosphazene effectively blocked the invasion of water, the modified zirconia sol and the urea-formaldehyde resin-aluminum dihydrogen phosphate could resist the influence of the high alkalinity of cement hydration on the composite aggregates, the carboxyethyl silane triol and the carboxylic acid groups of the polyethylene glycol monomethyl ether improved the compatibility and wettability of the composite aggregates with cement paste, and the interfacial bonding strength between the aggregates and the cement was significantly improved.

[0066] Test two: basic properties of refractory materials (1) High temperature stability: The refractory materials prepared in the examples and comparative examples were mixed with water, and samples of 40x40x160mm were prepared, standard curing for 24h, dried at 110°C for 24h, and then placed in a high temperature furnace, heated at a rate of 5°C / min to the target temperature: 400°C, 800°C, 1400°C, and after reaching the target temperature, held for 3h, cooled to room temperature with the furnace, and then the modulus of rupture was measured on a universal testing machine, compared with the modulus of rupture before treatment, and the modulus of rupture retention rate was calculated.

[0067] (2) Long-term durability: The refractory materials prepared in the examples and comparative examples were mixed with water, and samples of 40x40x160mm were prepared, standard curing for 24h, dried at 110°C for 24h, and then placed in an autoclave, treated at 120°C under saturated steam pressure for 3h, and the treated samples were observed for cracking and pulverization, the modulus of rupture after treatment was measured, compared with the modulus of rupture before treatment, and the modulus of rupture retention rate was calculated.

[0068]

[0069] The basic properties of the refractory material are shown in Table 2. From the data in the table, at 400℃, the organic matter begins to decompose, at this time, the viscous liquid phase of aluminum dihydrogen phosphate plays a role of bonding, preventing the strength from suddenly dropping, at 800℃, the organic matter completely decomposes, at this time, the strength drops to the lowest, with the temperature increasing to 1400℃, at this time, AlPO4, CaZrO3, MgAl2O3 are successively generated, constituting a multi-phase refractory structure, further improving the bending 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 block the erosion of high-temperature and high-pressure water vapor, and the material has excellent hydration resistance.

[0070] The above only describes the preferred embodiments of the present application and is not intended to limit the protection scope of the present application, and 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.

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 refractory material containing waste magnesia-calcium bricks according to claim 1, characterized in that, 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.

8. 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 7, 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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