Preparation method and application of aluminum ash-based long-term strength growth type high-aluminum cement

Abstract

The application discloses a preparation method and application of aluminum ash-based long-term strength growth type high-aluminum cement. The method utilizes citric acid and tartaric acid to modify aluminum ash, consumes active aluminum, dissolves heavy metal ions, removes soluble salt and AlN, and realizes harmless treatment of the aluminum ash. Then, the pretreated aluminum ash is mixed with steel slag, lime powder and other materials in proportion, calcined at a high temperature of 1350-1450 DEG C for 1 hour, and then subjected to an extremely cold modification process to promote the metastable hydration product to transform into a stable state to generate water garnet and tobermorite gel. The activity of the solid waste is improved through a planetary ball mill mechanical activation. The high-aluminum cement with long-term strength growth characteristics is prepared. The application also provides application of the high-aluminum cement in jet reinforcement and provides a slurry of the high-aluminum cement for preparing jet-reinforced mine surrounding rock. The application not only solves the environmental problems of industrial solid wastes such as aluminum ash, but also realizes resource utilization of the solid wastes.

Description

Technical Field

[0001] This invention relates to the field of cement preparation technology, specifically to a method for preparing and applying alumina-based high-alumina cement with long-term strength growth. Background Technology

[0002] Aluminum ash is a hazardous solid waste generated during the aluminum industry production process. According to GB18597-2001, "Standard for Pollution Control of Hazardous Waste Storage," aluminum ash is listed in the hazardous waste management catalog. Aluminum ash mainly contains Al₂O₃, AlN, metallic aluminum, and small amounts of Na, Mg, Ca, and Si, as well as small amounts of fluorides and chlorides. When aluminum ash comes into contact with water or humid air, the aluminum nitride it contains readily undergoes a hydrolysis reaction, producing ammonia gas with a pungent odor, causing air pollution. The metallic aluminum it contains reacts with water to produce hydrogen gas, and the aluminum carbide reacts with water to produce methane. Both hydrogen and methane pose a risk of combustion and explosion. Aluminum ash contains high levels of alkali metal oxides, as well as fluorides and chlorides. Long-term accumulation will pollute the soil and groundwater, seriously affecting the ecological environment and public health and safety.

[0003] Steel slag is a byproduct of the steel industry, with approximately 0.1-0.15 tons of slag produced for every ton of crude steel produced. As the world's largest steel producer, China produces over 100 million tons of steel slag annually, with accumulated stockpiles exceeding 1 billion tons. Fly ash is the fine ash collected from the flue gas after combustion in coal-fired power plant boilers, and is a major solid waste from coal-fired power plants. China's annual production is as high as 600-700 million tons, with accumulated stockpiles exceeding 3 billion tons.

[0004] High-alumina cement is a hydraulic cementitious material with aluminate as its main mineral component. It possesses characteristics such as rapid setting and early strength, high temperature resistance, and resistance to sulfate attack, and is widely used in the lining of high-temperature equipment such as industrial kilns, boilers, and casting furnaces. However, the later-stage strength of traditional high-alumina cement typically exhibits a downward trend. Generally, high-alumina cement concrete older than 5 years has a residual strength of only half or even less than its early strength. This is due to the degradation of hydration products (CAH) over time. 10 C2AH8 may gradually transform into the more stable C3AH6, and this transformation process accelerates with increasing ambient temperature. As a result of the crystal transformation, free water is released into the cement stone, increasing the pore volume. At the same time, because C3AH6 itself has low strength, the strength of the cement stone is significantly reduced.

[0005] Currently, aluminum ash treatment technologies mainly include pyrometallurgical treatment and hydrometallurgical treatment. Pyrometallurgical treatment primarily involves high-temperature calcination to oxidize AlN in the aluminum ash, generating Al2O3, while simultaneously removing harmful substances such as fluorides and chlorides. Hydrometallurgical treatment mainly involves reacting the aluminum ash with acidic or alkaline solutions to extract aluminum or other useful components. However, these treatment technologies typically focus only on the harmless treatment of aluminum ash, neglecting its resource utilization value. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing and applying alumina-based high-alumina cement with long-term strength growth, which solves the problems of low long-term strength and low resource utilization rate of high-alumina cement at present.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] A method for preparing alumina-based high-alumina cement with long-term strength growth specifically includes the following steps:

[0009] Step A1: Weigh the following raw materials by weight: 300-420 parts modified aluminum ash, 50-80 parts steel slag, 50-100 parts lime powder, 5-20 parts silicon-reinforcing material, 3-9 parts stabilizer and 1-2 parts grinding aid;

[0010] Step A2: Mix modified aluminum ash, steel slag, lime powder, silica reinforcing material and stabilizer, and calcine at 1350-1450℃ for 1 hour. Then, cool down to 30-35℃ within 10-20 minutes to obtain high-alumina cement clinker.

[0011] Step A3: Add high-alumina cement clinker to a new type of ball mill with a ball-to-material ratio of 10:1. Ball mill at a speed of 300-400 r / min and add grinding aid. After ball milling for 1 hour, add modified additives and mix evenly to obtain aluminum ash-based long-term strength-increasing high-alumina cement.

[0012] Furthermore, the modified aluminum ash described in step A1 is prepared by the following steps:

[0013] Aluminum ash and mixed acid are mixed and reacted at a temperature of 50-80℃ for 20-40 minutes. The filtrate is then removed by filtration and dried to obtain modified aluminum ash.

[0014] Furthermore, the mixed acid is a mixture of citric acid and tartaric acid in a molar ratio of 2:3, the pH value of the mixed acid is between 3 and 4, and the mass ratio of aluminum ash to the mixed acid is 2-3:5-8.

[0015] Furthermore, the specific surface area of ​​the steel slag powder mentioned in step A1 is 400-500 m². 2 / kg, CaO / SiO 2 / kg, CaO content >70%, the silica-reinforced material is a composite material of fly ash and silica fume, the mass ratio of fly ash to silica fume is 1:2-3, the fly ash is high-calcium fly ash, CaO content is high >10%, amorphous phase content ≥70%, and the specific surface area of ​​silica fume ≥18,000 m². 2 / kg, with an amorphous SiO2 content of 85-98%, and a stabilizer of a composite material of chabazite and apatite in a mass ratio of 1:3-5. The chabazite contains >70% SiO2+Al2O2, and the apatite contains >80% calcium phosphate. The grinding aid is a mixture of glycerol, sodium polyacrylate, sodium oleate, and sodium dodecylbenzenesulfonate in a mass ratio of 1:0.5-0.7:0.1-0.3:0.1-0.3. The ratio is 1-2, and the specific surface area of ​​the lime powder is 150-250 m² / kg.

[0016] Furthermore, the modified additive is prepared by the following steps:

[0017] Step B1: Thioglycerol is dissolved in anhydrous dichloromethane. Under conditions of 150-200 r / min and 0°C, triethylamine and acetyl chloride are added while stirring. The mixture is heated to 20-25°C and reacted for 2-4 hours to obtain intermediate 1. Intermediate 1, 4-formylphenylboronic acid, 4A molecular sieve, p-toluenesulfonic acid and tetrahydrofuran are mixed and purged with nitrogen. Under conditions of 200-300 r / min and 35-40°C, the mixture is reacted for 6-8 hours to obtain intermediate 2. Intermediate 2 is dissolved in methanol. Under conditions of 150-200 r / min and 20-25°C, potassium carbonate is added while stirring and the mixture is reacted for 1-1.5 hours to obtain the modifier.

[0018] Step B2: Disperse nano-silica in ethanol, stir and add γ-aminopropyltriethoxysilane and deionized water at a speed of 200-300 r / min and a temperature of 70-75℃, and react for 4-6 h to obtain aminated nano-silica. Mix the aminated nano-silica, modifier, p-toluenesulfonic acid and toluene evenly, and react at a speed of 150-200 r / min and a temperature of 110-115℃ for 4-6 h to obtain modified nano-silica.

[0019] Step B3: Mix polyvinyl alcohol and dimethyl sulfoxide, stir for 1-1.5 hours at a speed of 150-200 r / min and a temperature of 90-95℃, then cool to 85-90℃, add acrylic acid, p-toluenesulfonic acid and hydroquinone, and react for 4-6 hours to obtain modified polyvinyl alcohol. Mix modified polyvinyl alcohol, modified nano silica, benzophenone and N,N-dimethylformamide, and react for 1-1.5 hours at a speed of 120-150 r / min and under 365nm ultraviolet light irradiation to obtain modified additive.

[0020] Furthermore, the molar ratio of thioglycerol, triethylamine and acetyl chloride in step B1 is 1:1.1:1.05, the molar ratio of intermediate 1 and 4-formylbenzeneboronic acid is 1:1, the amount of p-toluenesulfonic acid is 5 mol% of 4-formylbenzeneboronic acid, and the amount of 4A molecular sieve is 50% of the mass of 4-formylbenzenesulfonic acid.

[0021] Furthermore, the amount of γ-aminopropyltriethoxysilane used in step B2 is 3% of the mass of nano-silica, the molar ratio of amino groups on the aminated nano-silica to the modifier is 1:1, and the amount of p-toluenesulfonic acid used is 1% of the mass of the modifier.

[0022] Furthermore, in step B3, the mass ratio of polyvinyl alcohol to acrylic acid is 20:1, the amount of p-toluenesulfonic acid is 2% of the mass of acrylic acid, the amount of hydroquinone is 0.5% of the mass of acrylic acid, the mass ratio of modified polyvinyl alcohol to modified nano silica is 10:1, and the amount of benzophenone is 0.02% of the mass of modified polyvinyl alcohol.

[0023] Furthermore, a slurry for preparing a long-term strength-enhancing high-alumina cement based on aluminum ash and capable of being sprayed to reinforce surrounding rock in mine tunnels specifically includes the following steps:

[0024] After mixing high-alumina cement and steel slag powder evenly, water and water-reducing agent are added, and the mixture is stirred for 3-5 minutes at a speed of ≥1000 r / min to obtain a slurry that can be sprayed to reinforce the surrounding rock of mine tunnels.

[0025] Furthermore, the mass ratio of the high-alumina cement, steel slag aggregate, water, and water-reducing agent is 1:1-1.5:0.4-0.5:0.01-0.2, the CaO / SiO2 ratio of the steel slag aggregate is 1-2, the fineness modulus is 2.3-3, the moisture content is 4-6%, and the water-reducing agent is prepared by mixing polycarboxylate water-reducing agent, melamine water-reducing agent, and sodium lignosulfonate water-reducing agent in a mass ratio of 1:0.5-0.7:0.5-0.7.

[0026] The beneficial effects of this invention are as follows: This invention discloses an aluminum ash-based high-alumina cement with long-term strength enhancement, comprising the following raw materials: modified aluminum ash, steel slag, lime powder, silica reinforcing material, stabilizer, modifying additives, and grinding aid. In the silica reinforcing material, the active silicon in the silica powder and fly ash reacts with Al2O3 at high temperature to generate fibrous Si3N4 or mullite, forming a network reinforcing phase, significantly improving the compressive and flexural strength of the material; it can delay the transformation of the hydration products of high-alumina cement to the C3AH6 crystal form, reducing strength loss under high temperature and high humidity conditions. The apatite in the stabilizer reacts with Pb to form a stable mineral; chalcogenide can utilize its porous structure to exchange cations and adsorb heavy metals such as Pb and Cd. The synergistic effect of these two materials significantly solidifies heavy metal ions in the aluminum ash. The synergistic effect of citric acid and tartaric acid in the modified aluminum ash can effectively consume the active aluminum in the aluminum ash, dissolve heavy metal ions, and remove soluble salts and AlN. Citric acid can achieve a desorption rate of 75%-87.76% for heavy metals such as Cd, Cr, and Mn, and good desorption effects can be achieved even under weakly acidic conditions. Tartaric acid forms stable complexes with metal ions, which can promote the hydrolysis of AlN to generate Al(OH)3 and NH4+. + This pretreatment step enables the harmless treatment of aluminum ash while improving its resource utilization value.

[0027] The modified additive reacts with acetyl chloride as a raw material to form a thiol-protected group, yielding intermediate 1. Intermediate 1 is then reacted with 4-formylphenylboronic acid, causing the diol group on intermediate 1 to react with the borate group of 4-formylphenylboronic acid, forming a five-membered ring borate ester, yielding intermediate 2. Intermediate 2 is deprotected with potassium carbonate to obtain the modifier. Nano-silica is treated with γ-aminopropyltriethoxysilane to graft amino groups onto the surface of the nano-silica, yielding aminated nano-silica. The aminated nano-silica is then reacted with the modifier, causing the amino groups on the aminated nano-silica to react with the aldehyde (DA) groups on the modifier, yielding modified nano-silica. Polyethylene... The esterification reaction of alcohol and acrylic acid esterifies some of the hydroxyl groups on polyvinyl alcohol and acrylic acid, producing modified polyvinyl alcohol. The modified polyvinyl alcohol and modified nano-silica are then reacted with ultraviolet light, causing the double bonds on the modified polyvinyl alcohol and the thiol groups on the modified nano-silica to react, producing a modified additive. The addition of the modified additive causes the hydroxyl groups on the surface to form dense hydrogen bonds with the surface of the hydration products, resulting in chemical adsorption. When subjected to external force, the modified additive detaches from the cement matrix, and the interface slips. Furthermore, the modified additive contains five-membered ring borate esters and imine groups, which means that the detachment of the modified additive consumes a large amount of energy, thereby increasing the toughness and impact resistance of high-alumina cement.

[0028] The preparation process employs a combination of high-temperature calcination followed by mechanical activation, ensuring the glass content and improving the strength of high-alumina cement. The ultracold modification, through rapid cooling, freezes the metastable products from the initial hydration stage, preventing them from further transforming into unstable phases over time. Simultaneously, rapid cooling promotes the directional transformation of hydration products, generating stable gels such as hydrogarnet and sucralose, thereby achieving long-term strength growth in high-alumina cement. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Example 1: A method for preparing alumina-based high-alumina cement with long-term strength growth, specifically including the following steps:

[0031] Step A1: Weigh the following raw materials by weight: 300 parts modified aluminum ash, 50 parts steel slag, 50 parts lime powder, 5 parts silica reinforcing material, 3 parts stabilizer, 5 parts modified additive and 1 part grinding aid.

[0032] Step A2: Mix modified aluminum ash, steel slag, lime powder, silica reinforcing material and stabilizer, and calcine at 1350℃ for 1 hour, then cool down to 30℃ within 10 minutes to obtain high-alumina cement clinker.

[0033] Step A3: Add high-alumina cement clinker to a new type of ball mill with a ball-to-material ratio of 10:1. Ball mill at a speed of 300 r / min and add grinding aid. After ball milling for 1 hour, add modified additives and mix evenly to obtain aluminum ash-based long-term strength-increasing high-alumina cement.

[0034] The modified aluminum ash described in step A1 is prepared by the following steps:

[0035] Aluminum ash and mixed acid were mixed and reacted at 50°C for 20 minutes. The filtrate was then filtered to remove the residue and dried to obtain modified aluminum ash.

[0036] The mixed acid is a mixture of citric acid and tartaric acid in a molar ratio of 2:3, with sulfonic acid having a pH value between 3 and 3, and aluminum ash to mixed acid in a mass ratio of 2:5.

[0037] The specific surface area of ​​the steel slag powder mentioned in step A1 is 400 m². 2 / kg, CaO / SiO 2 / kg, CaO content 70%, the silica-reinforcing material is a composite material of fly ash and silica fume, the mass ratio of fly ash to silica fume is 1:2, the fly ash is high-calcium fly ash, CaO content is high at 12%, amorphous phase content is 70%, and the specific surface area of ​​silica fume is 18,000 m². 2 / kg, with an amorphous SiO2 content of 85%, and a stabilizer consisting of a composite material of chabazite and apatite in a mass ratio of 1:3. The chabazite contains 72% SiO2 + Al2O2, and the apatite contains 82% calcium phosphate. The grinding aid is a mixture of glycerol, sodium polyacrylate, sodium oleate, and sodium dodecylbenzenesulfonate in a mass ratio of 1:0.5:0.1:0.1. The ratio is 1, and the specific surface area of ​​the lime powder is 150 m².

[0038] The modified additive is prepared by the following steps:

[0039] Step B1: Thioglycerol was dissolved in anhydrous dichloromethane. Under conditions of 150 r / min and 0°C, the mixture was stirred and triethylamine and acetyl chloride were added. The mixture was heated to 20°C and reacted for 2 h to obtain intermediate 1. Intermediate 1, 4-formylphenylboronic acid, 4A molecular sieve, p-toluenesulfonic acid and tetrahydrofuran were mixed and purged with nitrogen. Under conditions of 200 r / min and 35°C, the mixture was reacted for 6 h to obtain intermediate 2. Intermediate 2 was dissolved in methanol. Under conditions of 150 r / min and 20°C, the mixture was stirred and potassium carbonate was added. The mixture was reacted for 1 h to obtain the modifier.

[0040] Step B2: Disperse nano-silica in ethanol, stir and add γ-aminopropyltriethoxysilane and deionized water at a speed of 200 r / min and a temperature of 70℃, and react for 4 h to obtain aminated nano-silica. Mix the aminated nano-silica, modifier, p-toluenesulfonic acid and toluene evenly, and react at a speed of 150 r / min and a temperature of 110℃ for 4 h to obtain modified nano-silica.

[0041] Step B3: Polyvinyl alcohol and dimethyl sulfoxide are mixed and stirred for 1 hour at 150 r / min and 90°C. Then, the mixture is cooled to 85°C, and acrylic acid, p-toluenesulfonic acid, and hydroquinone are added. The mixture is reacted for 4 hours to obtain modified polyvinyl alcohol. Modified polyvinyl alcohol, modified nano-silica, benzophenone, and N,N-dimethylformamide are mixed and reacted for 1 hour at 120 r / min and 365 nm ultraviolet light irradiation to obtain modified additive.

[0042] The molar ratio of thioglycerol, triethylamine and acetyl chloride in step B1 is 1:1.1:1.05, the molar ratio of intermediate 1 and 4-formylbenzeneboronic acid is 1:1, the amount of p-toluenesulfonic acid is 5 mol% of 4-formylbenzeneboronic acid, and the amount of 4A molecular sieve is 50% of the mass of 4-formylbenzenesulfonic acid.

[0043] The amount of γ-aminopropyltriethoxysilane used in step B2 is 3% of the mass of nano-silica, the molar ratio of amino groups on the aminated nano-silica to the modifier is 1:1, and the amount of p-toluenesulfonic acid used is 1% of the mass of the modifier.

[0044] In step B3, the mass ratio of polyvinyl alcohol to acrylic acid is 20:1, the amount of p-toluenesulfonic acid is 2% of the mass of acrylic acid, the amount of hydroquinone is 0.5% of the mass of acrylic acid, the mass ratio of modified polyvinyl alcohol to modified nano silica is 10:1, and the amount of benzophenone is 0.02% of the mass of modified polyvinyl alcohol.

[0045] A slurry for preparing long-term strength-enhancing high-alumina cement based on aluminum ash, which can be sprayed to reinforce surrounding rock in mine tunnels, specifically includes the following steps:

[0046] After mixing high-alumina cement and steel slag powder evenly, water and water-reducing agent are added, and the mixture is stirred for 3 minutes at a speed of 1000 r / min to obtain a slurry that can be sprayed to reinforce the surrounding rock of mine tunnels.

[0047] The mass ratio of the high-alumina cement, steel slag aggregate, water, and water-reducing agent is 1:1:0.4:0.01. The CaO / SiO2 ratio of the steel slag aggregate is 1, the fineness modulus is 2.3, and the moisture content is 4%. The water-reducing agent is prepared by mixing polycarboxylate water-reducing agent, melamine water-reducing agent, and sodium lignosulfonate water-reducing agent in a mass ratio of 1:0.5:0.5.

[0048] Example 2, a method for preparing alumina-based high-alumina cement with long-term strength growth, specifically includes the following steps:

[0049] Step A1: Weigh the following raw materials by weight: 360 parts modified aluminum ash, 65 parts steel slag, 75 parts lime powder, 12 parts silicon-reinforcing material, 6 parts stabilizer, 6.5 parts modified additive and 1.5 parts grinding aid;

[0050] Step A2: Mix modified aluminum ash, steel slag, lime powder, siliceous reinforcing material and stabilizer, and calcine at 1400℃ for 1 hour, then cool down to 30℃ within 15 minutes to obtain high-alumina cement clinker.

[0051] Step A3: Add high-alumina cement clinker to a new type of ball mill with a ball-to-material ratio of 10:1. Ball mill at a speed of 300 r / min and add grinding aid. After ball milling for 1 hour, add modified additives and mix evenly to obtain aluminum ash-based long-term strength-increasing high-alumina cement.

[0052] The modified aluminum ash described in step A1 is prepared by the following steps:

[0053] Aluminum ash and mixed acid were mixed and reacted at 65°C for 30 minutes. The filtrate was then filtered to remove the residue and dried to obtain modified aluminum ash.

[0054] The mixed acid is a mixture of citric acid and tartaric acid in a molar ratio of 2:3, with sulfonic acid having a pH value between 4 and 4, and aluminum ash to mixed acid in a mass ratio of 2.5:6.5.

[0055] The specific surface area of ​​the steel slag powder mentioned in step A1 is 450 m². 2 / kg, CaO / SiO 2 / kg, CaO content 75%, the silica-reinforcing material is a composite material of fly ash and silica fume, the mass ratio of fly ash to silica fume is 1:3, the fly ash is high-calcium fly ash, CaO content is high at 15%, amorphous phase content is 72%, and the specific surface area of ​​silica fume is 18500 m². 2 / kg, with an amorphous SiO2 content of 90%, and a stabilizer consisting of a composite material of chabazite and apatite in a mass ratio of 1:4. The chabazite contains 75% SiO2 + Al2O2, and the apatite contains 85% calcium phosphate. The grinding aid is a mixture of glycerol, sodium polyacrylate, sodium oleate, and sodium dodecylbenzenesulfonate in a mass ratio of 1:0.6:0.2:0.2. The ratio is 1.5, and the specific surface area of ​​the lime powder is 200 m².

[0056] The modified additive is prepared by the following steps:

[0057] Step B1: Thioglycerol was dissolved in anhydrous dichloromethane. Under conditions of 150 r / min and 0°C, the mixture was stirred and triethylamine and acetyl chloride were added. The mixture was heated to 25°C and reacted for 3 h to obtain intermediate 1. Intermediate 1, 4-formylphenylboronic acid, 4A molecular sieve, p-toluenesulfonic acid and tetrahydrofuran were mixed and purged with nitrogen. The mixture was reacted at 200 r / min and 40°C for 7 h to obtain intermediate 2. Intermediate 2 was dissolved in methanol. Under conditions of 150 r / min and 25°C, the mixture was stirred and potassium carbonate was added. The mixture was reacted for 1.3 h to obtain the modifier.

[0058] Step B2: Disperse nano-silica in ethanol, stir and add γ-aminopropyltriethoxysilane and deionized water at a speed of 200 r / min and a temperature of 75℃, and react for 5 h to obtain aminated nano-silica. Mix the aminated nano-silica, modifier, p-toluenesulfonic acid and toluene evenly, and react at a speed of 150 r / min and a temperature of 115℃ for 5 h to obtain modified nano-silica.

[0059] Step B3: Polyvinyl alcohol and dimethyl sulfoxide are mixed and stirred at 150 r / min and 95°C for 1.2 h. After stirring, the mixture is cooled to 90°C, and acrylic acid, p-toluenesulfonic acid, and hydroquinone are added. The mixture is then reacted for 5 h to obtain modified polyvinyl alcohol. Modified polyvinyl alcohol, modified nano-silica, benzophenone, and N,N-dimethylformamide are mixed and reacted at 120 r / min and 365 nm ultraviolet light for 1.5 h to obtain modified additive.

[0060] The molar ratio of thioglycerol, triethylamine and acetyl chloride in step B1 is 1:1.1:1.05, the molar ratio of intermediate 1 and 4-formylbenzeneboronic acid is 1:1, the amount of p-toluenesulfonic acid is 5 mol% of 4-formylbenzeneboronic acid, and the amount of 4A molecular sieve is 50% of the mass of 4-formylbenzenesulfonic acid.

[0061] The amount of γ-aminopropyltriethoxysilane used in step B2 is 3% of the mass of nano-silica, the molar ratio of amino groups on the aminated nano-silica to the modifier is 1:1, and the amount of p-toluenesulfonic acid used is 1% of the mass of the modifier.

[0062] In step B3, the mass ratio of polyvinyl alcohol to acrylic acid is 20:1, the amount of p-toluenesulfonic acid is 2% of the mass of acrylic acid, the amount of hydroquinone is 0.5% of the mass of acrylic acid, the mass ratio of modified polyvinyl alcohol to modified nano silica is 10:1, and the amount of benzophenone is 0.02% of the mass of modified polyvinyl alcohol.

[0063] A slurry for preparing long-term strength-enhancing high-alumina cement based on aluminum ash, which can be sprayed to reinforce surrounding rock in mine tunnels, specifically includes the following steps:

[0064] After mixing high-alumina cement and steel slag powder evenly, water and water-reducing agent are added, and the mixture is stirred for 4 minutes at a speed of 1200 r / min to obtain a slurry that can be sprayed to reinforce the surrounding rock of the mine.

[0065] The mass ratio of the high-alumina cement, steel slag aggregate, water, and water-reducing agent is 1:1.3:0.4:0.1. The CaO / SiO2 ratio of the steel slag aggregate is 1.5, the fineness modulus is 2.5, and the moisture content is 5%. The water-reducing agent is prepared by mixing polycarboxylate water-reducing agent, melamine water-reducing agent, and sodium lignosulfonate water-reducing agent in a mass ratio of 1:0.6:0.6.

[0066] Example 3: A method for preparing alumina-based high-alumina cement with long-term strength growth, specifically including the following steps:

[0067] Step A1: Weigh the following raw materials by weight: 420 parts modified aluminum ash, 80 parts steel slag, 100 parts lime powder, 20 parts silica reinforcing material, 9 parts stabilizer, 8 parts modified additives and 2 parts grinding aid.

[0068] Step A2: Mix modified aluminum ash, steel slag, lime powder, silica reinforcing material and stabilizer, and calcine at 1450℃ for 1 hour, then cool down to 35℃ within 20 minutes to obtain high-alumina cement clinker.

[0069] Step A3: Add high-alumina cement clinker to a new type of ball mill with a ball-to-material ratio of 10:1. Ball mill at a speed of 400 r / min and add grinding aid. After ball milling for 1 hour, add modified additives and mix evenly to obtain aluminum ash-based long-term strength-increasing high-alumina cement.

[0070] The modified aluminum ash described in step A1 is prepared by the following steps:

[0071] Aluminum ash and mixed acid were mixed and reacted at 80°C for 40 minutes. The filtrate was then filtered to remove the residue and dried to obtain modified aluminum ash.

[0072] The mixed acid is a mixture of citric acid and tartaric acid in a molar ratio of 2:3, with sulfonic acid having a pH value between 4 and 4, and aluminum ash to mixed acid in a mass ratio of 3:8.

[0073] The specific surface area of ​​the steel slag powder mentioned in step A1 is 500 m². 2 / kg, CaO / SiO 2 / kg, CaO content 80%, the silica-reinforcing material is a composite material of fly ash and silica fume, the mass ratio of fly ash to silica fume is 1:3, the fly ash is high-calcium fly ash, CaO content is high at 18%, amorphous phase content is 80%, and the specific surface area of ​​silica fume is 19000 m². 2 / kg, with an amorphous SiO2 content of 98%, and a stabilizer consisting of a composite material of chabazite and apatite in a mass ratio of 1:5. The chabazite contains 80% SiO2 + Al2O2, and the apatite contains 85% calcium phosphate. The grinding aid is a mixture of glycerol, sodium polyacrylate, sodium oleate, and sodium dodecylbenzenesulfonate in a mass ratio of 1:0.7:0.3:0.3. The ratio is 2, and the specific surface area of ​​the lime powder is 250 m².

[0074] The modified additive is prepared by the following steps:

[0075] Step B1: Thioglycerol was dissolved in anhydrous dichloromethane. Under conditions of 200 r / min and 0°C, the mixture was stirred and triethylamine and acetyl chloride were added. The mixture was heated to 25°C and reacted for 4 h to obtain intermediate 1. Intermediate 1, 4-formylphenylboronic acid, 4A molecular sieve, p-toluenesulfonic acid and tetrahydrofuran were mixed and purged with nitrogen. The mixture was reacted at 300 r / min and 40°C for 8 h to obtain intermediate 2. Intermediate 2 was dissolved in methanol. Under conditions of 200 r / min and 25°C, the mixture was stirred and potassium carbonate was added. The mixture was reacted for 1.5 h to obtain the modifier.

[0076] Step B2: Disperse nano-silica in ethanol, stir and add γ-aminopropyltriethoxysilane and deionized water at a speed of 300 r / min and a temperature of 75℃, and react for 6 h to obtain aminated nano-silica. Mix the aminated nano-silica, modifier, p-toluenesulfonic acid and toluene evenly, and react at a speed of 200 r / min and a temperature of 115℃ for 6 h to obtain modified nano-silica.

[0077] Step B3: Polyvinyl alcohol and dimethyl sulfoxide are mixed and stirred at 200 r / min and 95°C for 1.5 h. After cooling to 90°C, acrylic acid, p-toluenesulfonic acid and hydroquinone are added and reacted for 6 h to obtain modified polyvinyl alcohol. Modified polyvinyl alcohol, modified nano silica, benzophenone and N,N-dimethylformamide are mixed and reacted at 150 r / min and 365 nm ultraviolet light irradiation for 1.5 h to obtain modified additive.

[0078] The molar ratio of thioglycerol, triethylamine and acetyl chloride in step B1 is 1:1.1:1.05, the molar ratio of intermediate 1 and 4-formylbenzeneboronic acid is 1:1, the amount of p-toluenesulfonic acid is 5 mol% of 4-formylbenzeneboronic acid, and the amount of 4A molecular sieve is 50% of the mass of 4-formylbenzenesulfonic acid.

[0079] The amount of γ-aminopropyltriethoxysilane used in step B2 is 3% of the mass of nano-silica, the molar ratio of amino groups on the aminated nano-silica to the modifier is 1:1, and the amount of p-toluenesulfonic acid used is 1% of the mass of the modifier.

[0080] In step B3, the mass ratio of polyvinyl alcohol to acrylic acid is 20:1, the amount of p-toluenesulfonic acid is 2% of the mass of acrylic acid, the amount of hydroquinone is 0.5% of the mass of acrylic acid, the mass ratio of modified polyvinyl alcohol to modified nano silica is 10:1, and the amount of benzophenone is 0.02% of the mass of modified polyvinyl alcohol.

[0081] A slurry for preparing long-term strength-enhancing high-alumina cement based on aluminum ash, which can be sprayed to reinforce surrounding rock in mine tunnels, specifically includes the following steps:

[0082] After mixing high-alumina cement and steel slag powder evenly, water and water-reducing agent are added, and the mixture is stirred for 5 minutes at a speed of 2000 r / min to obtain a slurry that can be sprayed to reinforce the surrounding rock of mine tunnels.

[0083] The mass ratio of the high-alumina cement, steel slag aggregate, water, and water-reducing agent is 1:1.5:0.5:0.2. The CaO / SiO2 ratio of the steel slag aggregate is 2, the fineness modulus is 3, and the moisture content is 6%. The water-reducing agent is prepared by mixing polycarboxylate water-reducing agent, melamine water-reducing agent, and sodium lignosulfonate water-reducing agent in a mass ratio of 1:0.7:0.7.

[0084] Comparative Example 1: This comparative example does not include silicon-reinforcing materials compared to Example 1, but the remaining steps are the same.

[0085] Comparative Example 2: This comparative example did not include a stabilizer compared to Example 1, but the remaining steps were the same.

[0086] Comparative Example 3: This comparative example did not include a grinding aid as in Example 1, but the remaining steps were the same.

[0087] Comparative Example 4: Compared with Example 1, this comparative example uses P·O42.5 silicate cement instead of high-alumina cement, and the other steps are the same.

[0088] Comparative Example 5: This comparative example did not include any modifying additives compared to Example 1, but the remaining steps were the same.

[0089] The slurries for shotcreting and reinforcing the surrounding rock of mines prepared in Examples 1-3 and Comparative Examples 1-5 were tested for setting time, bond strength and compressive strength in accordance with the standard of "Technical Specification for Rock and Soil Anchors and Shotcrete Support Engineering" GB50086-2015. The test results are shown in Table 1.

[0090] Table 1

[0091]

[0092] Table 1 shows that this application has excellent mechanical strength, short setting time, and strong adhesion, better meeting the requirements for shotcrete reinforcement of surrounding rock in mines. Analysis of the comparative test results reveals that when silica-reinforcing materials, stabilizers, grinding aids, and modifying additives are not used, and when ordinary silicate cement is used instead of alumina-based high-alumina cement, the prepared shotcrete slurry exhibits poor performance. The setting time, compressive strength, and adhesion to surrounding rock are all lower than in the example, failing to meet the requirements of actual engineering standards.

[0093] The above description is merely an example and illustration of the concept of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the concept of the invention or exceed the scope defined in the claims, they should all fall within the protection scope of the present invention.

Claims

1. A method for preparing alumina-based high-alumina cement with long-term strength growth, characterized in that: Specifically, the steps include the following: Step A1: Weigh the following raw materials by weight: 300-420 parts modified aluminum ash, 50-80 parts steel slag, 50-100 parts lime powder, 5-20 parts silica reinforcing material, 3-9 parts stabilizer, 5-8 parts modified additives and 1-2 parts grinding aid. Step A2: Mix modified aluminum ash, steel slag, lime powder, silica reinforcing material and stabilizer, calcine them, and then cool them down to obtain high-alumina cement clinker. Step A3: Add the high-alumina cement clinker into a new type of ball mill, ball mill and add grinding aid. After ball milling, add the modifying additive and mix evenly to obtain aluminum ash-based long-term strength-increasing high-alumina cement. The modified aluminum ash described in step A1 is prepared by the following steps: After mixing and reacting aluminum ash and mixed acid, the filtrate is removed by filtration and then dried to obtain modified aluminum ash. The silica-reinforcing material mentioned in step A1 is a composite material of fly ash and silica fume, with a mass ratio of fly ash to silica fume of 1:2-3. The fly ash is high-calcium fly ash. The stabilizer is a composite material of chalcogenide and apatite, with a mass ratio of chalcogenide to apatite of 1:3-5. The grinding aid is a mixture of glycerol, sodium polyacrylate, sodium oleate, and sodium dodecylbenzenesulfonate in a mass ratio of 1:0.5-0.7:0.1-0.3:0.1-0.

3. The modified additive is prepared by the following steps: Step B1: Thioglycerol is dissolved in anhydrous dichloromethane, stirred and triethylamine and acetyl chloride are added, and the mixture is heated to prepare intermediate 1. Intermediate 1, 4-formylphenylboronic acid, 4A molecular sieve, p-toluenesulfonic acid and tetrahydrofuran are mixed, and nitrogen gas is introduced for protection to carry out the reaction to prepare intermediate 2. Intermediate 2 is dissolved in methanol, stirred and potassium carbonate is added to carry out the reaction to prepare the modifier. Step B2: Disperse nano-silica in ethanol, stir and add γ-aminopropyltriethoxysilane and deionized water to react and obtain aminated nano-silica. Mix and react the aminated nano-silica, modifier, p-toluenesulfonic acid and toluene to obtain modified nano-silica. Step B3: After mixing and stirring polyvinyl alcohol and dimethyl sulfoxide, the mixture is cooled and acrylic acid, p-toluenesulfonic acid and hydroquinone are added to react and obtain modified polyvinyl alcohol. Modified polyvinyl alcohol, modified nano silica, benzophenone and N,N-dimethylformamide are mixed and reacted with ultraviolet light to obtain modified additives.

2. The preparation method of the alumina-based long-term strength-enhancing high-alumina cement according to claim 1, characterized in that: The mixed acid is a mixture of citric acid and tartaric acid in a molar ratio of 2:3, with a pH value between 3 and 4, and a mass ratio of aluminum ash to mixed acid of 2-3:5-8.

3. The method for preparing alumina-based long-term strength-enhancing high-alumina cement according to claim 1, characterized in that: The molar ratio of thioglycerol, triethylamine and acetyl chloride in step B1 is 1:1.1:1.05, and the molar ratio of intermediate 1 and 4-formylphenylboronic acid is 1:

1.

4. The preparation method of the alumina-based long-term strength-enhancing high-alumina cement according to claim 1, characterized in that: The amount of γ-aminopropyltriethoxysilane used in step B2 is 3% of the mass of nano-silica, and the molar ratio of amino groups on the aminated nano-silica to the modifier is 1:

1.

5. The method for preparing alumina-based long-term strength-enhancing high-alumina cement according to claim 1, characterized in that: The mass ratio of polyvinyl alcohol to acrylic acid in step B3 is 20:1, and the mass ratio of modified polyvinyl alcohol to modified nano silica is 10:

1.

6. The high-alumina cement prepared by the preparation method according to claim 1 is used to prepare a slurry that can be sprayed to reinforce the surrounding rock of a mine, characterized in that: The specific steps include the following: after mixing high-alumina cement and steel slag powder evenly, add water and water-reducing agent, stir for 3-5 minutes to obtain a slurry that can be sprayed to reinforce the surrounding rock of the mine.

7. The slurry for jettisoning and reinforcing surrounding rock in mine tunnels according to claim 6, characterized in that: The mass ratio of the high-alumina cement, steel slag powder, water and water-reducing agent is 1:1-1.5:0.4-0.5:0.01-0.

2. The water-reducing agent is prepared by mixing polycarboxylate water-reducing agent, melamine water-reducing agent and sodium lignosulfonate water-reducing agent in a mass ratio of 1:0.5-0.7:0.5-0.7.

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