A prefabricated block refractory material for coke oven and preparation method thereof

Abstract

The invention discloses a prefabricated block refractory material for a coke oven and a preparation method thereof, and belongs to the technical field of refractory material processing, and is used to solve the technical problem in the prior art that the comprehensive performances of the prefabricated block refractory material, such as the refractory temperature, heat insulation performance, compressive strength and dimensional stability, need to be further improved; the invention uses self-made composite polysiloxane and pretreated fly ash as solid base materials, composite gel solution and reinforcing liquid as liquid reinforcing materials, and sodium dodecyl sulfate to form a castable, and performs post-casting curing and high-temperature roasting on the castable, so that not only the refractory temperature and compressive strength of the prefabricated refractory material are effectively improved, but also the thermal conductivity and linear expansion rate of the prefabricated refractory material are reduced, so that the refractory material has good heat insulation performance and dimensional stability.

Description

Technical Field

[0001] The invention relates to the technical field of refractory material processing, and in particular to a prefabricated block refractory material for a coking oven and a preparation method thereof. Background Art

[0002] A coke oven is also known as a coking oven. It is usually a furnace made of refractory bricks and refractory blocks. It is used to oxidize coal to produce coke. It is the main thermal equipment for coking. A modern coke oven refers to a horizontal chamber coke oven that produces metallurgical coke as its main purpose and can recover coking chemical products. It consists of a furnace body and ancillary equipment. As an important equipment in the steel industry, the operating stability and service life of the coking oven are directly related to the quality and efficiency of steel production. In the coking process, refractory materials play a vital role. They not only need to withstand extreme environments of high temperature and high pressure, but also need to have good corrosion resistance, thermal shock stability and mechanical strength.

[0003] Compared with traditional refractory materials, prefabricated block refractory materials have standard material sizes and are easy to install. Through factory production, strict control of raw material ratios and firing processes can ensure stable product quality. Prefabricated block refractory materials can be assembled and used on site, reducing on-site wet operations, shortening construction time and costs, reducing dust and exhaust emissions, and meeting environmental protection requirements.

[0004] At present, the prefabricated refractory materials widely used in coking ovens mainly include silica bricks, clay bricks, semi-silica bricks, etc. These materials have exposed a series of problems during long-term use. Although silica bricks have good thermal conductivity and high-temperature strength, during use, when silica bricks are heated to 1450°C, they will produce about 1.5-2.2% volume expansion, and the load softening point of silica bricks is low. The dimensional stability and high-temperature resistance of silica bricks need to be further improved, affecting their service life; clay bricks have good thermal shock stability, but are prone to shrinkage and expansion of brick joints under high temperature conditions, resulting in air leakage, affecting the sealing and life of the furnace body. Although semi-silica bricks have made up for the shortcomings of silica bricks and clay bricks to a certain extent, their comprehensive performance still needs to be improved.

[0005] In view of the technical defects in this aspect, a solution is now proposed. Summary of the invention

[0006] The object of the present invention is to provide a prefabricated block refractory material for a coke oven and a preparation method thereof, so as to solve the technical problem in the prior art that the comprehensive performance of the prefabricated block refractory material, such as refractory temperature, thermal insulation performance, compressive strength and dimensional stability, needs to be further improved.

[0007] The object of the present invention can be achieved by the following technical scheme: A method for preparing a prefabricated block refractory material for a coke oven comprises the following steps:

[0008] S1. Add aluminum sec-butoxide and isopropanol to a reactor and stir until the system is dissolved. The temperature of the reactor is raised to 75-80°C. Dilute nitric acid is added to the reactor and the reaction is carried out for 2-3 hours. Modified magnesium oxide is added to the reactor and stirred for 20-30 minutes. TEOS is added to the reactor and stirred for 2-3 hours. The mixture is cooled to room temperature to obtain a composite gel solution.

[0009] The synthetic reaction principle of the composite gel solution is:

[0010] Aluminum 2-butoxide is used as an aluminum source. Under acidic conditions, aluminum 2-butoxide will undergo a hydrolysis reaction to generate aluminum ions and corresponding alcohols. Tetraethyl orthosilicate is a silicate ester. Under acidic conditions, it will hydrolyze to generate silicate ions, which can undergo a condensation reaction with the generated aluminum ions and modified magnesium oxide with a large number of hydroxyl groups on the surface to form complexes such as aluminosilicate or magnesium aluminosilicate. By extending the reaction time, the tetraethyl orthosilicate is fully hydrolyzed and fully mixed and reacted with other reactants, which promotes the condensation reaction of silicate ions with aluminum ions, modified magnesium oxide and other reactants, gradually forming a gel with a three-dimensional network structure, and obtaining a composite gel solution.

[0011] S2, adding the composite polysiloxane, pretreated fly ash, composite gel solution and reinforcing liquid into a reaction kettle and stirring, stirring and mixing for 20-30 minutes at room temperature, adding sodium dodecyl sulfate into the reaction kettle, stirring for 30-50 minutes, and obtaining a castable;

[0012] S3, adding the castable material into the mold, and then transferring the mold to a drying oven at a temperature of 40-50° C. and curing for 4-6 days to obtain a prefabricated refractory body;

[0013] S4, roasting the prefabricated refractory material body to prepare the prefabricated refractory material.

[0014] Wherein, in step S1, the preparation method of modified magnesium oxide is:

[0015] A1. Add isocyanate propyl triethoxysilane and tetrahydrofuran into a nitrogen-protected reactor and stir. Raise the temperature of the reactor to 45-50° C., add 2-hydroxyethylamine into the reactor, keep the temperature for 2-3 hours, and perform post-treatment to obtain modified ethoxysilane.

[0016] The synthetic reaction formula of modified ethoxysilane is:

[0017]

[0018] A2. Add nano magnesium oxide, modified ethoxysilane and anhydrous ethanol into a reactor and stir. The temperature of the reactor is raised to 55-60°C. Add 0.5 mol / L sodium hydroxide solution into the reactor and keep the reaction temperature for 3-5 hours. Post-process to obtain modified magnesium oxide.

[0019] The synthetic reaction principle of modified magnesium oxide is:

[0020] The reactivity of amino group with isocyanate group is higher than that of hydroxyl group with isocyanate group. Nitrogen protection is to prevent the reactants or products from being oxidized by oxygen in the air. The isocyanate group in the isocyanatepropyltriethoxysilane molecule can undergo condensation reaction with the amino group in 2-hydroxyethylamine under nitrogen environment to generate modified ethoxysilane containing carbamate bond. The mass spectrum data of modified ethoxysilane are m / z: 308.1767 (100.0%), 309.1801 (13.0%), 309.1763 (5.1%), 310.1736 (3.3%), 310.1810 (1.0%).

[0021] The ethoxy groups in the modified ethoxysilane undergo hydrolysis reaction under alkaline conditions to generate silanol groups, which undergo condensation reaction with hydroxyl groups on the surface of nano-magnesium oxide to form silicon-oxygen bonds, thereby connecting the modified ethoxysilane to the surface of nano-magnesium oxide to prepare modified magnesium oxide.

[0022] Pretreated fly ash is processed by the following steps:

[0023] C1. Add fly ash into a muffle furnace, raise the temperature of the muffle furnace to 800-900°C, keep the temperature for 3-5h, and naturally cool it to room temperature to obtain activated fly ash;

[0024] C2, adding activated fly ash and potassium carbonate into a ball mill, and mixing by ball milling for 30-50 minutes to obtain mixed fly ash, wherein the weight ratio of the activated fly ash to potassium carbonate is 10g:3-5g;

[0025] C3. Add the mixed fly ash and the mixed acid into a reactor and stir, raise the temperature of the reactor to 80-90°C, keep warm and stir for 40-60min, and perform post-treatment to obtain pretreated fly ash, wherein the amount ratio of the mixed fly ash and the mixed acid is 1g:6-7mL, and the mixed acid is composed of acetic acid and 1mol / L nitric acid in a volume ratio of 1:6-8, and the post-treatment comprises: after the reaction is completed, lowering the temperature of the reactor to room temperature, filtering, washing the filter cake with purified water until it is neutral and then draining, transferring the filter cake to a drying oven at a temperature of 85-95°C, and drying to constant weight to obtain pretreated fly ash.

[0026] The synthetic reaction principle of pretreated fly ash is:

[0027] At high temperatures, some mineral components in fly ash will undergo phase change or decomposition reactions, accompanied by changes in volume and release of gas, resulting in the formation of new pores inside the particles or the expansion of existing pores. As the temperature rises, the mineral components in the fly ash particles will undergo thermal expansion. When the temperature reaches and remains in the high temperature range of 800-900°C, this thermal expansion effect is particularly significant. Subsequently, during the insulation stage and the cooling process, the mineral components will experience a certain degree of contraction due to temperature changes. This uneven thermal expansion and contraction will cause stress inside the particles, thereby changing the original pore structure and increasing the total volume and connectivity of the pores. In the ball mill, the activated fly ash and Potassium carbonate is mixed and ground under the action of mechanical force. The mechanical force not only makes the two substances fully mixed, but also may destroy the particle structure of fly ash and potassium carbonate, increase its specific surface area, and promote the subsequent reaction. The addition of potassium carbonate can also react with the active silicate in the fly ash to generate potassium silicate or potassium aluminate, etc., stimulate the activity of the fly ash, and prepare for the subsequent reaction with acid; the mixed fly ash and the mixed acid composed of acetic acid and nitric acid are stirred and reacted in a reactor. Acetic acid and nitric acid, as acid solvents, can destroy the structure of minerals such as silicate and aluminate in the fly ash, dissolve the metal elements therein in the form of ions, and prepare a porous structure pretreated fly ash with a low metal content.

[0028] Furthermore, the preparation method of the enhancement liquid is as follows: polyvinyl alcohol and purified water are added to a reactor and stirred, the temperature of the reactor is increased to 85-90°C, stirred until the system is dissolved, tetramethylammonium hydroxide solution is added to the reactor, and the reaction mixture is stirred for 30-50 minutes to obtain an enhancement liquid, wherein the amount ratio of the polyvinyl alcohol, purified water, and tetramethylammonium hydroxide solution is 1g:70mL:30mL, and the tetramethylammonium hydroxide solution is composed of tetramethylammonium hydroxide and purified water in a ratio of 1g:3mL.

[0029] Furthermore, in step S1, the dosage ratio of the aluminum butylate, isopropanol, dilute nitric acid, modified magnesium oxide, and tetraethyl orthosilicate is 8-10g:70mL:15mL:3-4g:12-15g, and the concentration of the dilute nitric acid is 0.2-0.5mol / L; in step S2, the weight ratio of the composite polysiloxane, pretreated fly ash, composite gel solution, reinforcing liquid, and sodium dodecyl sulfate is 4-6:3-5:10-20:3-4:0.2.

[0030] Further, in step S4, the calcining method of the prefabricated refractory body is as follows: the prefabricated refractory body is transferred to a tubular furnace, the tubular furnace is heated to 100-110°C at a heating rate of 5-7°C / min, and kept warm for 40-60min, then heated to 700-750°C at a heating rate of 5-7°C / min, and kept warm for 25-35min, and then heated to 1150-1250°C at a heating rate of 8-10°C / min, and kept warm for 90-120min to obtain the prefabricated refractory material.

[0031] Furthermore, in step A1, the amount ratio of the isocyanate propyl triethoxysilane and 2-hydroxyethylamine is 1 mol: 1 mol, the amount ratio of the isocyanate propyl triethoxysilane and tetrahydrofuran is 1 g: 7 mL, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is increased to 55 ° C, and the solvent is evaporated under reduced pressure to obtain modified ethoxysilane; in step A2, the amount ratio of the nano magnesium oxide, modified ethoxysilane, anhydrous ethanol and 0.5 mol / L sodium hydroxide solution is 5g: 2g: 30mL: 10mL, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is lowered to room temperature, suction filtration, the filter cake is washed with purified water until neutral and then dried, and the filter cake is transferred to a drying oven at a temperature of 60-70 ° C, and dried to constant weight to obtain modified magnesium oxide.

[0032] Further, the composite polysiloxane is processed by the following steps:

[0033] B1, adding trimethoxychlorosilane, trimethoxysilane, tetramethoxysilane and anhydrous ethanol into a reaction kettle and stirring, raising the temperature of the reaction kettle to 50-60° C., adding hydrochloric acid solution into the reaction kettle, keeping the temperature for reaction for 4-6 hours, and post-treating to obtain polysiloxane;

[0034] B2, adding polysiloxane, dichloro(dipropylamino)borane and n-octane into a nitrogen-protected autoclave and stirring, lowering the temperature of the autoclave to 3-8°C, adding nonamethyltrisilazane into the autoclave in batches, keeping warm and stirring for 40-60min, raising the temperature of the autoclave to 180-200°C at a heating rate of 3-5°C / min, keeping warm and reacting for 20-30h, and post-treating to obtain a composite polysiloxane precursor;

[0035] B3. Add the composite polysiloxane, divinylbenzene, n-octane and catalyst into a nitrogen-protected reactor and stir. Raise the temperature of the reactor to reflux the system, keep the temperature to react for 18-22 hours, and perform post-treatment to obtain the composite polysiloxane.

[0036] The synthetic reaction principle of composite polysiloxane is:

[0037] Trimethoxychlorosilane, trimethoxysilane and tetramethoxysilane are hydrolyzed and then recombined and polycondensed under an acidic environment to prepare a polysiloxane cross-linked with silicon-oxygen-silicon bonds; after polysiloxane and dichloro(dipropylamino)borane are mixed at low temperature, nonamethyltrisilazane is added to the reaction system; at low temperature, nonamethyltrisilazane can interact with the active sites on the surface of polysiloxane to form a preliminary reaction product; as the temperature gradually increases, the reaction rate accelerates, more nonamethyltrisilazane molecules participate in the reaction, and further cross-link or functionalize with the polysiloxane to generate a composite polysiloxane precursor having Si, B, C, N elements and active groups such as Si-H and NH; under the action of a catalyst, the active sites in the composite polysiloxane precursor undergo a silylation hydroaddition reaction with divinylbenzene, and divinylbenzene is used as a cross-linking agent to form covalent bonds with the active sites on the polysiloxane chain to construct a composite polysiloxane with a three-dimensional network structure.

[0038] Further, in step B1, the amount ratio of trimethoxysilyl chloride, trimethoxysilane, tetramethoxysilane, anhydrous ethanol and hydrochloric acid solution is 3g:3g:2g:60mL:10g, the concentration of the hydrochloric acid solution is 2mol / L, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is reduced to 40-50°C, ethanol is evaporated under reduced pressure, the temperature of the reactor is reduced to room temperature, n-hexane is added to the reactor, the mixture is stirred for 20-30min, the liquid is separated by standing, the aqueous phase is removed, the organic phase is washed twice with purified water, and then dried with anhydrous magnesium sulfate for 2h, filtered, and the filtrate is transferred to a rotary evaporator at a temperature of 45-55°C, and the solvent is evaporated under reduced pressure to obtain polysiloxane; in step B2, the polysiloxane, dichloro(dichloro) The amount ratio of propylamino) borane, n-octane and nonamethyltrisilazane is 5-7g:1-2g:30mL:1-2g, and the post-treatment comprises: after the reaction is completed, the high-pressure reactor is kept at 180-200°C, and the solvent is evaporated under reduced pressure to obtain a composite polysiloxane precursor; in step B3, the amount ratio of the composite polysiloxane, divinylbenzene, n-octane and catalyst is 10g:7g:13mL:0.03g, and the post-treatment comprises: after the reaction is completed, the reaction system is guided out of the reactor while hot, cooled to room temperature naturally, immersed in cyclohexane solvent, replaced for 6h, replaced with cyclohexane, repeated replacement 5 times, transferred to a freeze dryer at a temperature of -40°C, freeze-dried to constant weight, and obtained A composite polysiloxane.

[0039] The invention discloses a prefabricated block refractory material for a coke oven. The prefabricated block refractory material for a coke oven is prepared by adopting a preparation method of the prefabricated block refractory material for a coke oven.

[0040] The present invention has the following beneficial effects:

[0041] 1. The prefabricated block refractory material for coke oven of the present invention is prepared by using composite polysiloxane and pretreated fly ash as solid base materials, composite gel solution and reinforcing liquid as liquid reinforcing materials, and sodium dodecyl sulfate to form a castable, and curing and high-temperature calcining the castable after casting to obtain a prefabricated refractory material with a high porosity structure; low-temperature drying and curing promotes the initial cross-linking and curing reaction between the components in the castable, forming a prefabricated refractory material embryo with a relatively stable structure; under a high-temperature environment, the components in the prefabricated refractory material embryo are further cross-linked and cured to form a more stable three-dimensional network structure; at the same time, the organic mineral components in the prefabricated refractory material embryo undergo phase change or decomposition reaction at high temperature to generate new compounds and form more pore structures; these pore structures not only reduce the thermal conductivity of the material, but also further improve its thermal insulation performance and high-temperature resistance; in addition, high-temperature calcination also eliminates residual stress and defects in the castable, and improves the mechanical properties of the material.

[0042] 2. The prefabricated block refractory material for coke oven of the present invention uses sodium dodecyl sulfate as an air entraining agent during preparation, and introduces a large number of tiny bubbles to increase the porosity of concrete. These bubbles play a role in lubricating and dispersing cement particles in concrete, which helps to improve the workability and performance of concrete. The polyvinyl alcohol in the reinforcing liquid forms a solution with a certain viscosity and strength under the action of tetramethylammonium hydroxide, which cooperates with sodium dodecyl sulfate to further promote the splitting of bubbles to form uniform and more tiny bubbles, so that the tiny bubbles in the pouring liquid remain stable in the pouring liquid, and the porous structure of the pretreated fly ash further increases the porosity of the prefabricated refractory material, thereby further improving the thermal insulation performance of the prefabricated refractory material; the reinforcing liquid can also It penetrates into the pores and particle gaps of the castable, plays a role of bonding and reinforcement, and provides good early strength support for the prefabricated refractory body. By modifying the nano-magnesium oxide and improving its reaction activity, a composite gel with three-dimensional network cross-linking of aluminum, silicon and magnesium elements is prepared. After the composite gel is mixed with the composite polysiloxane, in a high temperature environment, the active groups such as Si-H and NH in the composite polysiloxane further participate in the cross-linking reaction with the composite gel and cooperate with the pretreated fly ash to form a stable porcelain-like structure. The composite gel solution is sintered at high temperature to form a strong three-dimensional network structure, which provides strength and stability for the prefabricated refractory material, and cooperates with the modified fly ash and the composite polysiloxane to further improve the refractory temperature, compressive strength and dimensional stability of the material. DETAILED DESCRIPTION

[0043] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] Example 1

[0045] This embodiment provides a method for preparing a prefabricated block refractory material for a coke oven, comprising the following steps:

[0046] S1. Preparation of modified magnesium oxide

[0047] Weigh: 24.7 g of isocyanatepropyltriethoxysilane and 172.9 mL of tetrahydrofuran are added to a nitrogen-protected reactor and stirred. The temperature of the reactor is raised to 45° C., 6.1 g of 2-hydroxyethylamine is added to the reactor, and the reaction is kept warm for 2 hours. After the reaction is completed, the temperature of the reactor is raised to 55° C., and the solvent is evaporated under reduced pressure to obtain modified ethoxysilane;

[0048] Weigh: 20 g of nano magnesium oxide, 8 g of modified ethoxysilane, and 120 mL of anhydrous ethanol, add them into a reactor and stir, raise the temperature of the reactor to 55°C, add 40 mL of 0.5 mol / L sodium hydroxide solution into the reactor, and keep the reaction warm for 3 hours. After the reaction is completed, lower the temperature of the reactor to room temperature, filter, wash the filter cake with purified water until it is neutral, and then drain, transfer the filter cake to a drying oven at a temperature of 60°C, and dry it to constant weight to obtain modified magnesium oxide.

[0049] S2. Preparation of composite gel solution

[0050] Weigh: 80 g of aluminum sec-butoxide and 700 mL of isopropanol are added to a reactor and stirred until the system is dissolved. The temperature of the reactor is raised to 75°C. 150 mL of 0.2 mol / L dilute nitric acid is added to the reactor and the reaction is kept warm for 2 h. 30 g of modified magnesium oxide is added to the reactor and stirred for 20 min. 120 g of tetraethyl orthosilicate is added to the reactor and the mixture is kept warm and stirred for 2-3 h. The mixture is naturally cooled to room temperature to obtain a composite gel solution.

[0051] S3. Preparation of composite polysiloxane

[0052] Weigh: 30 g of trimethoxychlorosilane, 30 g of trimethoxysilane, 20 g of tetramethoxysilane, and 600 mL of anhydrous ethanol, add them to a reactor and stir, raise the temperature of the reactor to 50° C., add 100 mL of 2 mol / L hydrochloric acid solution to the reactor, and keep the temperature for 4 hours. After the reaction is completed, lower the temperature of the reactor to 40° C., evaporate the ethanol under reduced pressure, lower the temperature of the reactor to room temperature, add 500 mL of n-hexane to the reactor, keep the temperature and stir for 20 minutes, stand for separation, remove the aqueous phase, wash the organic phase twice with purified water, dry it with anhydrous magnesium sulfate for 2 hours, filter it, transfer the filtrate to a rotary evaporator at a temperature of 45° C., and evaporate the solvent under reduced pressure to obtain polysiloxane;

[0053] Weigh: 100-140 g of polysiloxane, 20 g of dichloro(dipropylamino)borane, and 600 mL of n-octane, add them into a nitrogen-protected autoclave and stir, lower the temperature of the autoclave to 3° C., add 20 g of nonamethyltrisilazane in batches into the autoclave, keep warm and stir for 40 min, heat the autoclave to 180° C. at a heating rate of 3° C. / min, keep warm and react for 20 h, after the reaction is completed, keep the autoclave at 180° C., and evaporate the solvent under reduced pressure to obtain a composite polysiloxane precursor;

[0054] Weigh: 100 g of composite polysiloxane, 70 g of divinylbenzene, 130 mL of n-octane and 0.3 g of chloroplatinic acid, add them into a nitrogen-protected reactor and stir, raise the temperature of the reactor to reflux the system, and keep the reaction warm for 18 hours. After the reaction is completed, the reaction system is guided out of the reactor while hot, naturally cooled to room temperature, and immersed in cyclohexane solvent. After replacement for 6 hours, cyclohexane is replaced, and the replacement is repeated 5 times. Then, it is transferred to a freeze dryer at a temperature of -40°C and freeze-dried to constant weight to obtain a composite polysiloxane.

[0055] S4. Preparation of pretreated fly ash

[0056] The fly ash is added into a muffle furnace, the temperature of the muffle furnace is raised to 800°C, the temperature is kept and roasted for 3 hours, and the temperature is naturally lowered to room temperature to obtain activated fly ash;

[0057] Weigh: 200 g of activated fly ash and 60 g of potassium carbonate, add them into a ball mill, and mix them by ball milling for 30 minutes to obtain mixed fly ash;

[0058] The acetic acid and 1 mol / L nitric acid were mixed uniformly in a volume ratio of 1:6 to obtain a mixed acid;

[0059] Weigh: 200 g of mixed fly ash and 1200 mL of mixed acid are added to the reactor and stirred. The temperature of the reactor is increased to 80°C, and the mixture is kept warm and stirred for 40 minutes. The temperature of the reactor is lowered to room temperature, and the filter cake is washed with purified water until it is neutral and then dried. The filter cake is transferred to a drying oven at 85°C and dried to constant weight to obtain pretreated fly ash.

[0060] S5. Preparation of Enhancement Solution

[0061] Tetramethylammonium hydroxide and purified water were mixed uniformly at a dosage ratio of 1 g:3 mL to obtain a tetramethylammonium hydroxide solution;

[0062] Weigh: 2 g of polyvinyl alcohol and 140 mL of purified water, add them into a reactor and stir. Raise the temperature of the reactor to 85° C. and stir until the system is dissolved. Add 60 mL of tetramethylammonium hydroxide solution into the reactor and stir at this temperature for 30 minutes to obtain an enhanced solution.

[0063] S6. Preparation of casting materials

[0064] Weigh: 400 g of composite polysiloxane, 300 g of pretreated fly ash, 1000 mL of composite gel solution, and 300 g of reinforcing liquid, add into a reactor and stir, stir and mix at room temperature for 20 min, add 20 g of sodium dodecyl sulfate into the reactor, stir for 30 min, and obtain a castable.

[0065] S7. Preparation of prefabricated refractory materials

[0066] The castable is added into the mold, and then the mold is transferred to a drying oven at a temperature of 40° C. and cured for 4 days to obtain a prefabricated refractory body;

[0067] The prefabricated refractory body was transferred to a tubular furnace, and the temperature was increased to 100°C at a heating rate of 5°C / min, kept warm for 40 minutes, then increased to 700°C at a heating rate of 5°C / min, kept warm for 25 minutes, and then increased to 1150°C at a heating rate of 8°C / min, kept warm for 90 minutes to obtain a prefabricated refractory material.

[0068] Example 2

[0069] This embodiment provides a method for preparing a prefabricated block refractory material for a coke oven, comprising the following steps:

[0070] S1. Preparation of modified magnesium oxide

[0071] Weigh: 24.7 g of isocyanatepropyltriethoxysilane and 172.9 mL of tetrahydrofuran are added to a nitrogen-protected reactor and stirred. The temperature of the reactor is raised to 47° C., 6.1 g of 2-hydroxyethylamine is added to the reactor, and the reaction is kept warm for 2.5 hours. After the reaction is completed, the temperature of the reactor is raised to 55° C., and the solvent is evaporated under reduced pressure to obtain modified ethoxysilane;

[0072] Weigh: 20 g of nano magnesium oxide, 8 g of modified ethoxysilane, and 120 mL of anhydrous ethanol, add them into a reactor and stir, raise the temperature of the reactor to 57°C, add 40 mL of 0.5 mol / L sodium hydroxide solution into the reactor, and keep the reaction warm for 4 hours. After the reaction is completed, lower the temperature of the reactor to room temperature, filter, wash the filter cake with purified water until it is neutral, and then drain, transfer the filter cake to a drying oven at a temperature of 65°C, and dry it to constant weight to obtain modified magnesium oxide.

[0073] S2. Preparation of composite gel solution

[0074] Weigh: 90 g of aluminum sec-butoxide and 700 mL of isopropanol are added to a reactor and stirred until the system is dissolved. The temperature of the reactor is raised to 77°C. 150 mL of 0.35 mol / L dilute nitric acid is added to the reactor and the reaction is kept warm for 2.5 h. 35 g of modified magnesium oxide is added to the reactor and stirred for 25 min. 135 g of tetraethyl orthosilicate is added to the reactor and the mixture is kept warm and stirred for 2.5 h. The mixture is naturally cooled to room temperature to obtain a composite gel solution.

[0075] S3. Preparation of composite polysiloxane

[0076] Weigh: 30 g of trimethoxychlorosilane, 30 g of trimethoxysilane, 20 g of tetramethoxysilane, and 600 mL of anhydrous ethanol, add them to a reactor and stir, raise the temperature of the reactor to 55°C, add 100 mL of 2 mol / L hydrochloric acid solution to the reactor, and keep the temperature for 5 hours. After the reaction is completed, lower the temperature of the reactor to 45°C, evaporate the ethanol under reduced pressure, lower the temperature of the reactor to room temperature, add 500 mL of n-hexane to the reactor, keep the temperature and stir for 25 minutes, stand for separation, remove the aqueous phase, wash the organic phase twice with purified water, dry it with anhydrous magnesium sulfate for 2 hours, filter it, transfer the filtrate to a rotary evaporator at a temperature of 50°C, and evaporate the solvent under reduced pressure to obtain polysiloxane;

[0077] Weigh: 120 g of polysiloxane, 30 g of dichloro(dipropylamino)borane, and 600 mL of n-octane, add them into a nitrogen-protected autoclave and stir, the temperature of the autoclave is reduced to 5.5° C., 30 g of nonamethyltrisilazane is added to the autoclave in batches, and the mixture is stirred for 50 min. The autoclave is heated to 190° C. at a heating rate of 4° C. / min, and the reaction is carried out for 25 h. After the reaction is completed, the autoclave is heated at 190° C., and the solvent is evaporated under reduced pressure to obtain a composite polysiloxane precursor;

[0078] Weigh: 100 g of composite polysiloxane, 70 g of divinylbenzene, 130 mL of n-octane and 0.3 g of chloroplatinic acid, add them into a nitrogen-protected reactor and stir, raise the temperature of the reactor to reflux the system, and keep the reaction warm for 20 hours. After the reaction is completed, the reaction system is guided out of the reactor while hot, naturally cooled to room temperature, and immersed in cyclohexane solvent. After replacement for 6 hours, cyclohexane is replaced, and the replacement is repeated 5 times. Then, it is transferred to a freeze dryer at a temperature of -40°C and freeze-dried to constant weight to obtain a composite polysiloxane.

[0079] S4. Preparation of pretreated fly ash

[0080] The fly ash is added into a muffle furnace, the temperature of the muffle furnace is raised to 850°C, the temperature is kept and roasted for 4 hours, and the temperature is naturally lowered to room temperature to obtain activated fly ash;

[0081] Weigh: 200 g of activated fly ash and 80 g of potassium carbonate, add them into a ball mill, and mix them by ball milling for 40 minutes to obtain mixed fly ash;

[0082] Mix acetic acid and 1 mol / L nitric acid in a volume ratio of 1:7 to obtain a mixed acid;

[0083] Weigh: 200 g of mixed fly ash and 1300 mL of mixed acid are added to the reactor and stirred. The temperature of the reactor is raised to 85°C and stirred for 50 minutes. The temperature of the reactor is lowered to room temperature and filtered. The filter cake is washed with purified water until it is neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 90°C and dried to constant weight to obtain pretreated fly ash.

[0084] S5. Preparation of Enhancement Solution

[0085] Tetramethylammonium hydroxide and purified water were mixed uniformly at a dosage ratio of 1 g:3 mL to obtain a tetramethylammonium hydroxide solution;

[0086] Weigh: 2 g of polyvinyl alcohol and 140 mL of purified water, add them into a reactor and stir. Raise the temperature of the reactor to 87° C. and stir until the system is dissolved. Add 60 mL of tetramethylammonium hydroxide solution into the reactor and stir at this temperature for 40 minutes to obtain an enhanced solution.

[0087] S6. Preparation of casting materials

[0088] Weigh: 500 g of composite polysiloxane, 400 g of pretreated fly ash, 1500 mL of composite gel solution, and 350 g of reinforcing liquid, add into a reactor and stir, stir and mix at room temperature for 25 min, add 20 g of sodium dodecyl sulfate into the reactor, stir for 40 min, and obtain a castable.

[0089] S7. Preparation of prefabricated refractory materials

[0090] Add the castable material into the mold, then transfer the mold to a drying oven at a temperature of 45°C and cure for 5 days to obtain a prefabricated refractory body;

[0091] The prefabricated refractory body was transferred to a tubular furnace, and the temperature was increased to 105°C at a heating rate of 6°C / min, kept warm for 50 minutes, then increased to 725°C at a heating rate of 6°C / min, kept warm for 30 minutes, and then increased to 1200°C at a heating rate of 9°C / min, kept warm for 110 minutes to obtain a prefabricated refractory material.

[0092] Example 3

[0093] This embodiment provides a method for preparing a prefabricated block refractory material for a coke oven, comprising the following steps:

[0094] S1. Preparation of modified magnesium oxide

[0095] Weigh: 24.7 g of isocyanatepropyltriethoxysilane and 172.9 mL of tetrahydrofuran are added to a nitrogen-protected reactor and stirred. The temperature of the reactor is raised to 50° C., 6.1 g of 2-hydroxyethylamine is added to the reactor, and the reaction is kept warm for 3 hours. After the reaction is completed, the temperature of the reactor is raised to 55° C., and the solvent is evaporated under reduced pressure to obtain modified ethoxysilane;

[0096] Weigh: 20 g of nano magnesium oxide, 8 g of modified ethoxysilane, and 120 mL of anhydrous ethanol, add them into a reactor and stir, raise the temperature of the reactor to 60°C, add 40 mL of 0.5 mol / L sodium hydroxide solution into the reactor, and keep the reaction warm for 5 hours. After the reaction is completed, lower the temperature of the reactor to room temperature, filter, wash the filter cake with purified water until it is neutral, and then drain, transfer the filter cake to a drying oven at a temperature of 70°C, and dry it to constant weight to obtain modified magnesium oxide.

[0097] S2. Preparation of composite gel solution

[0098] Weigh: 100 g of aluminum sec-butoxide and 700 mL of isopropanol are added to a reactor and stirred until the system is dissolved. The temperature of the reactor is raised to 80°C. 150 mL of 0.5 mol / L dilute nitric acid is added to the reactor and the reaction is kept warm for 3 h. 40 g of modified magnesium oxide is added to the reactor and stirred for 30 min. 150 g of tetraethyl orthosilicate is added to the reactor and the mixture is kept warm and stirred for 2-3 h. The mixture is naturally cooled to room temperature to obtain a composite gel solution.

[0099] S3. Preparation of composite polysiloxane

[0100] Weigh: 30 g of trimethoxychlorosilane, 30 g of trimethoxysilane, 20 g of tetramethoxysilane, and 600 mL of anhydrous ethanol, add them to a reactor and stir, raise the temperature of the reactor to 60°C, add 100 mL of 2 mol / L hydrochloric acid solution to the reactor, and keep the temperature for 6 hours. After the reaction is completed, lower the temperature of the reactor to 50°C, evaporate the ethanol under reduced pressure, lower the temperature of the reactor to room temperature, add 500 mL of n-hexane to the reactor, keep the temperature and stir for 30 minutes, let stand to separate, remove the aqueous phase, wash the organic phase twice with purified water, dry it with anhydrous magnesium sulfate for 2 hours, filter it, transfer the filtrate to a rotary evaporator at a temperature of 55°C, and evaporate the solvent under reduced pressure to obtain polysiloxane;

[0101] Weigh: 140 g of polysiloxane, 40 g of dichloro(dipropylamino)borane, and 600 mL of n-octane, add them into a nitrogen-protected autoclave and stir, lower the temperature of the autoclave to 8° C., add 40 g of nonamethyltrisilazane in batches into the autoclave, keep warm and stir for 60 min, heat the autoclave to 200° C. at a heating rate of 5° C. / min, keep warm and react for 30 h, after the reaction is completed, keep the autoclave at 200° C., and evaporate the solvent under reduced pressure to obtain a composite polysiloxane precursor;

[0102] Weigh: 100 g of composite polysiloxane, 70 g of divinylbenzene, 130 mL of n-octane and 0.3 g of chloroplatinic acid, add them into a nitrogen-protected reactor and stir, raise the temperature of the reactor to reflux the system, and keep the reaction warm for 22 hours. After the reaction is completed, the reaction system is guided out of the reactor while hot, naturally cooled to room temperature, and immersed in cyclohexane solvent. After replacement for 6 hours, cyclohexane is replaced, and the replacement is repeated 5 times. Then, it is transferred to a freeze dryer at a temperature of -40°C and freeze-dried to constant weight to obtain a composite polysiloxane.

[0103] S4. Preparation of pretreated fly ash

[0104] The fly ash is added into a muffle furnace, the temperature of the muffle furnace is raised to 900°C, the temperature is kept and roasted for 5 hours, and the temperature is naturally lowered to room temperature to obtain activated fly ash;

[0105] Weigh: 200 g of activated fly ash and 100 g of potassium carbonate, add them into a ball mill, and mix them by ball milling for 50 min to obtain mixed fly ash;

[0106] The acetic acid and 1 mol / L nitric acid were mixed uniformly in a volume ratio of 1:8 to obtain a mixed acid;

[0107] Weigh: 200 g of mixed fly ash and 1400 mL of mixed acid are added to the reactor and stirred. The temperature of the reactor is increased to 90°C, and the mixture is kept warm and stirred for 60 minutes. The temperature of the reactor is lowered to room temperature, and the filter cake is washed with purified water until it is neutral and then dried. The filter cake is transferred to a drying oven at a temperature of 95°C and dried to constant weight to obtain pretreated fly ash.

[0108] S5. Preparation of Enhancement Solution

[0109] Tetramethylammonium hydroxide and purified water were mixed uniformly at a dosage ratio of 1 g:3 mL to obtain a tetramethylammonium hydroxide solution;

[0110] Weigh: 2 g of polyvinyl alcohol and 140 mL of purified water, add them into a reactor and stir. Raise the temperature of the reactor to 90° C. and stir until the system is dissolved. Add 60 mL of tetramethylammonium hydroxide solution into the reactor and stir at this temperature for 50 minutes to obtain an enhanced solution.

[0111] S6. Preparation of casting materials

[0112] Weigh: 600 g of composite polysiloxane, 500 g of pretreated fly ash, 2000 mL of composite gel solution, and 400 g of reinforcing liquid, add into a reactor and stir, stir and mix at room temperature for 30 min, add 20 g of sodium dodecyl sulfate into the reactor, stir for 50 min, and obtain a castable.

[0113] S7. Preparation of prefabricated refractory materials

[0114] The castable is added into the mold, and then the mold is transferred to a drying oven at a temperature of 50° C. and cured for 6 days to obtain a prefabricated refractory body;

[0115] The prefabricated refractory body was transferred to a tubular furnace, and the temperature was increased to 110°C at a heating rate of 7°C / min, kept warm for 60 minutes, then increased to 750°C at a heating rate of 7°C / min, kept warm for 35 minutes, and then increased to 1250°C at a heating rate of 10°C / min, kept warm for 120 minutes to obtain a prefabricated refractory material.

[0116] Comparative Example 1

[0117] The difference between this comparative example and Example 3 is that step S1 is omitted and modified magnesium oxide is not added in step S2.

[0118] Comparative Example 2

[0119] The difference between this comparative example and Example 3 is that step S1 is eliminated, and the modified magnesium oxide in step S2 is replaced by magnesium oxide in step S1.

[0120] Comparative Example 3

[0121] The difference between this comparative example and Example 3 is that in step S2, the composite polysiloxane is replaced by a composite polysiloxane precursor.

[0122] Comparative Example 4

[0123] The difference between this comparative example and Example 3 is that in step S2, polysiloxane is used instead of the composite polysiloxane precursor to participate in the preparation of the composite polysiloxane.

[0124] Comparative Example 5

[0125] The difference between this comparative example and Example 3 is that step S4 is eliminated, and the pretreated fly ash in step S6 is replaced by the fly ash in step S4.

[0126] Comparative Example 6

[0127] The difference between this comparative example and Example 3 is that no tetramethylammonium hydroxide solution is added to the enhancement solution in step S5 during preparation.

[0128] Performance Test:

[0129] The fire resistance, thermal insulation and mechanical strength of the prefabricated refractory materials prepared in Examples 1-3 and Comparative Examples 1-6 were tested. The fire resistance was measured by referring to the standard GB / T 7322-2017 "Test method for refractories" to determine the fire resistance temperature of the sample. The thermal insulation was measured by referring to the standard GB / T 37796-2019 "Test method for thermal conductivity of insulating refractory materials (calorimeter method)" to determine the thermal conductivity of the sample. The mechanical strength was measured by referring to the standard GB / T 34218-2017 "Test method for high temperature compressive strength of refractory materials" and the standard GB / T 7320-2018 "Test method for thermal expansion of refractory materials" to determine the compressive strength and linear expansion rate of the sample at room temperature and 1000°C. The specific test results are shown in Table 1:

[0130] Table 1. Performance test data of samples

[0131] Data Analysis:

[0132] A comparative analysis of the data in Table 1 shows that the refractory temperature of the prefabricated refractory material prepared by the present invention reaches 1810°C, the thermal conductivity is reduced to 0.1273W / (m·K), the compressive strength at room temperature reaches 58.9MPa, the compressive strength at a high temperature of 1000°C reaches 13.6MPa, and the linear expansion rate is reduced to 0.10%. All performance test data are better than those of the comparative example, indicating that the present invention uses homemade composite polysiloxane and pretreated fly ash as solid base materials, composite gel solution and reinforcing liquid as liquid reinforcing materials, and sodium dodecyl sulfate to form a castable, and by curing and high-temperature calcining the castable after pouring, not only the refractory temperature and compressive strength of the prefabricated refractory material are effectively improved, but also the thermal conductivity and linear expansion rate of the prefabricated refractory material are reduced, so that the refractory material has good thermal insulation performance and dimensional stability.

[0133] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

[0134] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0135] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing a prefabricated block refractory material for a coke oven, characterized in that: The following steps are involved: S1. Add aluminum sec-butoxide and isopropanol to a reactor and stir until the system is dissolved. The temperature of the reactor is raised to 75-80°C. Dilute nitric acid is added to the reactor and the reaction is carried out for 2-3 hours. Modified magnesium oxide is added to the reactor and stirred for 20-30 minutes. TEOS is added to the reactor and stirred for 2-3 hours. The mixture is cooled to room temperature to obtain a composite gel solution. S2, adding the composite polysiloxane, pretreated fly ash, composite gel solution and reinforcing liquid into a reaction kettle and stirring, stirring and mixing for 20-30 minutes at room temperature, adding sodium dodecyl sulfate into the reaction kettle, stirring for 30-50 minutes, and obtaining a castable; S3, adding the castable material into the mold, and then transferring the mold to a drying oven at a temperature of 40-50° C. and curing for 4-6 days to obtain a prefabricated refractory body; S4, roasting the prefabricated refractory material body to prepare a prefabricated refractory material; Wherein, the preparation method of modified magnesium oxide is: A1. Add isocyanate propyl triethoxysilane and tetrahydrofuran into a nitrogen-protected reactor and stir. Raise the temperature of the reactor to 45-50° C., add 2-hydroxyethylamine into the reactor, keep the temperature for 2-3 hours, and perform post-treatment to obtain modified ethoxysilane. A2, adding nano magnesium oxide, modified ethoxysilane and anhydrous ethanol into a reactor and stirring, raising the temperature of the reactor to 55-60°C, adding 0.5 mol / L sodium hydroxide solution into the reactor, keeping the temperature for 3-5 hours, and post-treating to obtain modified magnesium oxide; Pretreated fly ash is processed by the following steps: C1. Add fly ash into a muffle furnace, raise the temperature of the muffle furnace to 800-900°C, keep the temperature for 3-5h, and naturally cool it to room temperature to obtain activated fly ash; C2, adding activated fly ash and potassium carbonate into a ball mill, and mixing by ball milling for 30-50 minutes to obtain mixed fly ash, wherein the weight ratio of the activated fly ash to potassium carbonate is 10g:3-5g; C3, adding the mixed fly ash and the mixed acid into a reactor and stirring, raising the temperature of the reactor to 80-90° C., keeping the temperature and stirring for 40-60 min, and post-treating to obtain pretreated fly ash, wherein the amount ratio of the mixed fly ash and the mixed acid is 1 g: 6-7 mL, and the mixed acid is composed of acetic acid and 1 mol / L nitric acid in a volume ratio of 1: 6-8; The preparation method of the enhancement liquid is as follows: polyvinyl alcohol and purified water are added to a reactor and stirred, the temperature of the reactor is increased to 85-90° C., the system is stirred until dissolved, tetramethylammonium hydroxide solution is added to the reactor, and the reaction mixture is stirred for 30-50 minutes to obtain the enhancement liquid, wherein the amount ratio of the polyvinyl alcohol, purified water and tetramethylammonium hydroxide solution is 1g:70mL:30mL, and the tetramethylammonium hydroxide solution is composed of tetramethylammonium hydroxide and purified water in an amount ratio of 1g:3mL.

2. The method for preparing a prefabricated block refractory material for a coke oven according to claim 1, characterized in that: In step S1, the dosage ratio of aluminum sec-butoxide, isopropanol, dilute nitric acid, modified magnesium oxide, and tetraethyl orthosilicate is 8-10g:70mL:15mL:3-4g:12-15g, and the concentration of the dilute nitric acid is 0.2-0.5mol / L; in step S2, the weight ratio of the composite polysiloxane, pretreated fly ash, composite gel solution, reinforcing liquid, and sodium dodecyl sulfate is 4-6:3-5:10-20:3-4:0.

2.

3. The method for preparing a prefabricated block refractory material for a coke oven according to claim 1, characterized in that: In step S4, the prefabricated refractory body is calcined as follows: the prefabricated refractory body is transferred to a tubular furnace, the tubular furnace is heated to 100-110°C at a heating rate of 5-7°C / min, and kept warm for 40-60min, then heated to 700-750°C at a heating rate of 5-7°C / min, and kept warm for 25-35min, and then heated to 1150-1250°C at a heating rate of 8-10°C / min, and kept warm for 90-120min to obtain the prefabricated refractory material.

4. The method for preparing a prefabricated block refractory material for a coke oven according to claim 1, characterized in that: In step A1, the amount ratio of isocyanatepropyl triethoxysilane and 2-hydroxyethylamine is 1 mol:1 mol, and the amount ratio of isocyanatepropyl triethoxysilane and tetrahydrofuran is 1 g:7 mL; in step A2, the amount ratio of nano-magnesium oxide, modified ethoxysilane, anhydrous ethanol and 0.5 mol / L sodium hydroxide solution is 5 g:2 g:30 mL:10 mL.

5. The method for preparing a prefabricated block refractory material for a coke oven according to claim 1, characterized in that: The composite polysiloxane is processed by the following steps: B1, adding trimethoxychlorosilane, trimethoxysilane, tetramethoxysilane and anhydrous ethanol into a reaction kettle and stirring, raising the temperature of the reaction kettle to 50-60° C., adding hydrochloric acid solution into the reaction kettle, keeping the temperature for reaction for 4-6 hours, and post-treating to obtain polysiloxane; B2, adding polysiloxane, dichloro(dipropylamino)borane and n-octane into a nitrogen-protected autoclave and stirring, lowering the temperature of the autoclave to 3-8°C, adding nonamethyltrisilazane into the autoclave in batches, keeping warm and stirring for 40-60min, raising the temperature of the autoclave to 180-200°C at a heating rate of 3-5°C / min, keeping warm and reacting for 20-30h, and post-treating to obtain a composite polysiloxane precursor; B3. Add the composite polysiloxane precursor, divinylbenzene, n-octane and catalyst into a nitrogen-protected reactor and stir. Raise the temperature of the reactor to reflux the system, keep the temperature for 18-22 hours, and perform post-treatment to obtain the composite polysiloxane.

6. The method for preparing a prefabricated block refractory material for a coke oven according to claim 5, characterized in that: In step B1, the amount ratio of trimethoxychlorosilane, trimethoxysilane, tetramethoxysilane, anhydrous ethanol and hydrochloric acid solution is 3g:3g:2g:60mL:10g, and the concentration of the hydrochloric acid solution is 2mol / L; in step B2, the amount ratio of polysiloxane, dichloro(dipropylamino)borane, n-octane and nonamethyltrisilazane is 5-7g:1-2g:30mL:1-2g; in step B3, the amount ratio of the composite polysiloxane precursor, divinylbenzene, n-octane and catalyst is 10g:7g:13mL:0.03g.

7. A prefabricated block refractory material for a coke oven, characterized in that: The prefabricated block refractory material for coking oven is prepared by the method for preparing a prefabricated block refractory material for coking oven as claimed in any one of claims 1 to 6.

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