CN113401915A - Ultra-light fibrous xonotlite type heat-insulating material based on amorphous silicon in fly ash and preparation method thereof - Google Patents
Ultra-light fibrous xonotlite type heat-insulating material based on amorphous silicon in fly ash and preparation method thereof Download PDFInfo
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- 239000010881 fly ash Substances 0.000 title claims abstract description 43
- UGGQKDBXXFIWJD-UHFFFAOYSA-N calcium;dihydroxy(oxo)silane;hydrate Chemical compound O.[Ca].O[Si](O)=O UGGQKDBXXFIWJD-UHFFFAOYSA-N 0.000 title claims abstract description 42
- 239000011810 insulating material Substances 0.000 title claims abstract description 23
- 229910021417 amorphous silicon Inorganic materials 0.000 title claims abstract description 12
- 238000002360 preparation method Methods 0.000 title claims description 10
- 239000007788 liquid Substances 0.000 claims abstract description 51
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 39
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 27
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 27
- 239000010703 silicon Substances 0.000 claims abstract description 27
- 238000000034 method Methods 0.000 claims abstract description 24
- 238000000605 extraction Methods 0.000 claims abstract description 23
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 16
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 16
- 239000004571 lime Substances 0.000 claims abstract description 16
- 239000008267 milk Substances 0.000 claims abstract description 15
- 210000004080 milk Anatomy 0.000 claims abstract description 15
- 235000013336 milk Nutrition 0.000 claims abstract description 15
- 239000002994 raw material Substances 0.000 claims abstract description 13
- 239000013078 crystal Substances 0.000 claims abstract description 10
- 239000007952 growth promoter Substances 0.000 claims abstract description 7
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 7
- 239000003513 alkali Substances 0.000 claims abstract description 6
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 6
- 238000001027 hydrothermal synthesis Methods 0.000 claims abstract description 6
- 238000004064 recycling Methods 0.000 claims abstract description 6
- 238000011978 dissolution method Methods 0.000 claims abstract description 4
- 239000002002 slurry Substances 0.000 claims description 43
- 238000010438 heat treatment Methods 0.000 claims description 27
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 26
- 239000000047 product Substances 0.000 claims description 21
- 238000006243 chemical reaction Methods 0.000 claims description 19
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 17
- 239000000706 filtrate Substances 0.000 claims description 15
- 238000003756 stirring Methods 0.000 claims description 15
- 238000005406 washing Methods 0.000 claims description 15
- 239000011575 calcium Substances 0.000 claims description 13
- 239000000835 fiber Substances 0.000 claims description 13
- 238000002156 mixing Methods 0.000 claims description 12
- 229910052681 coesite Inorganic materials 0.000 claims description 11
- 229910052906 cristobalite Inorganic materials 0.000 claims description 11
- 239000000377 silicon dioxide Substances 0.000 claims description 11
- 229910052682 stishovite Inorganic materials 0.000 claims description 11
- 229910052905 tridymite Inorganic materials 0.000 claims description 11
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium chloride Substances Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 claims description 10
- 239000011734 sodium Substances 0.000 claims description 10
- 230000018044 dehydration Effects 0.000 claims description 9
- 238000006297 dehydration reaction Methods 0.000 claims description 9
- 230000000694 effects Effects 0.000 claims description 9
- 238000001704 evaporation Methods 0.000 claims description 7
- 238000003825 pressing Methods 0.000 claims description 7
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 6
- 229910052791 calcium Inorganic materials 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 6
- 239000003365 glass fiber Substances 0.000 claims description 6
- 239000000463 material Substances 0.000 claims description 6
- 239000007787 solid Substances 0.000 claims description 6
- 238000009413 insulation Methods 0.000 claims description 5
- 238000000465 moulding Methods 0.000 claims description 5
- 235000019353 potassium silicate Nutrition 0.000 claims description 5
- 238000000926 separation method Methods 0.000 claims description 5
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 5
- 238000000967 suction filtration Methods 0.000 claims description 5
- 239000003245 coal Substances 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 4
- 229910003130 ZrOCl2·8H2O Inorganic materials 0.000 claims description 3
- 239000012774 insulation material Substances 0.000 claims description 3
- 229920000049 Carbon (fiber) Polymers 0.000 claims description 2
- 239000004699 Ultra-high molecular weight polyethylene Substances 0.000 claims description 2
- 229920006231 aramid fiber Polymers 0.000 claims description 2
- 239000004917 carbon fiber Substances 0.000 claims description 2
- 239000010883 coal ash Substances 0.000 claims description 2
- 238000001816 cooling Methods 0.000 claims description 2
- 238000007599 discharging Methods 0.000 claims description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 claims description 2
- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 claims description 2
- 238000005265 energy consumption Methods 0.000 abstract description 5
- 230000007613 environmental effect Effects 0.000 abstract description 2
- 239000012065 filter cake Substances 0.000 description 6
- 239000000378 calcium silicate Substances 0.000 description 4
- 229910052918 calcium silicate Inorganic materials 0.000 description 4
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 4
- 239000004698 Polyethylene Substances 0.000 description 3
- 238000009993 causticizing Methods 0.000 description 3
- 239000007795 chemical reaction product Substances 0.000 description 3
- -1 polyethylene Polymers 0.000 description 3
- 229920000573 polyethylene Polymers 0.000 description 3
- 238000004321 preservation Methods 0.000 description 3
- 239000010453 quartz Substances 0.000 description 3
- 230000035484 reaction time Effects 0.000 description 3
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- 239000006004 Quartz sand Substances 0.000 description 2
- 229910021486 amorphous silicon dioxide Inorganic materials 0.000 description 2
- 229910052799 carbon Inorganic materials 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229920002522 Wood fibre Polymers 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- 239000010425 asbestos Substances 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 description 1
- 239000000920 calcium hydroxide Substances 0.000 description 1
- 235000011116 calcium hydroxide Nutrition 0.000 description 1
- 229910001861 calcium hydroxide Inorganic materials 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000003889 chemical engineering Methods 0.000 description 1
- 239000000084 colloidal system Substances 0.000 description 1
- 238000000748 compression moulding Methods 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 239000010431 corundum Substances 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000002557 mineral fiber Substances 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 238000006386 neutralization reaction Methods 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000007780 powder milling Methods 0.000 description 1
- 239000012783 reinforcing fiber Substances 0.000 description 1
- 229910052895 riebeckite Inorganic materials 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 239000002025 wood fiber Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/20—Silicates
- C01B33/24—Alkaline-earth metal silicates
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/38—Fibrous materials; Whiskers
- C04B14/46—Rock wool ; Ceramic or silicate fibres
- C04B14/4643—Silicates other than zircon
- C04B14/465—Ca-silicate, e.g. wollastonite
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/24—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing alkyl, ammonium or metal silicates; containing silica sols
- C04B28/26—Silicates of the alkali metals
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/10—Particle morphology extending in one dimension, e.g. needle-like
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/20—Mortars, concrete or artificial stone characterised by specific physical values for the density
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/30—Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values
- C04B2201/32—Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values for the thermal conductivity, e.g. K-factors
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Organic Chemistry (AREA)
- Ceramic Engineering (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Structural Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Geology (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Civil Engineering (AREA)
- Silicates, Zeolites, And Molecular Sieves (AREA)
Abstract
The invention discloses an ultralight fibrous xonotlite type heat-insulating material based on amorphous silicon in fly ash and a method thereof. The method comprises the steps of extracting amorphous silicon in the fly ash by a high-temperature high-pressure alkali dissolution method, taking fly ash silicon extraction liquid as a main siliceous raw material, taking lime milk as a main calcareous raw material, adding a crystal growth promoter, and preparing the ultralight fibrous xonotlite heat-insulating material by adopting a dynamic hydrothermal synthesis process. Compared with the traditional process, the hydrothermal synthesis temperature and synthesis time of the invention are obviously reduced, the energy consumption is obviously reduced, and all performance indexes of the prepared xonotlite heat-insulating material are obviously improved, especially the density is reduced by more than 50 percent compared with the traditional process and is only 100kg/m3And about, the ultra-light level is achieved. Meanwhile, the NaOH solution used in the invention can realizeThe method has the advantages of recycling, greatly improving the utilization value of the fly ash, being an important way for realizing high-value utilization of the fly ash, and having remarkable economic, environmental and social benefits.
Description
Technical Field
The invention relates to the field of interdisciplines of chemical engineering and materials, in particular to an ultralight fibrous xonotlite type heat-insulating material based on amorphous silicon in fly ash and a preparation method thereof.
Background
The energy structure of rich coal, less gas and poor oil in China results in that about 6.5 million tons of fly ash are discharged every year in China. And because coal resources and population distribution in China are uneven, economic development is east-west and south-north unbalanced, the utilization rate of the fly ash in developed regions of the south China and the east China coastal regions is more than 95%, while the utilization rate of the fly ash in regions of the northwest China and the north China, such as inner Mongolia, Shanxi, Shaanxi, Ningxia and Xinjiang, is only about 20%, and the fly ash is massively stockpiled, so that the local ecological environment is seriously damaged.
As a substance with pozzolanic activity, the traditional utilization mode mainly focuses on cement and concrete, and the added value is low although the utilization amount is high. Therefore, the high-value utilization of the fly ash is an important measure for realizing the development strategy of 'carbon peak reaching' and 'carbon neutralization'. The main phase of the fly ash is amorphous SiO2Mullite, and small amount of quartz and corundum, amorphous SiO2As a substance with high reaction activity, the compound has good solubility in alkaline environment, so the compound can be extracted by an alkaline dissolution method and is used with high value.
Xonotlite (6 CaO.6SiO)2·H2O) is a monoclinic system, and is a good heat insulation material because the microstructure of the monoclinic system is prism-shaped crystals or fibrous aggregates and has better high temperature resistance. The traditional xonotlite type heat-insulating material is prepared by taking siliceous raw materials (quartz sand powder and diatomite), calcareous raw materials (lime and slaked lime) and reinforcing fibers (such as wood fibers, asbestos, glass fibers and the like) as main raw materials, dynamically hydrothermally synthesizing xonotlite in a high-temperature high-pressure reaction kettle, and carrying out processes such as compression molding, drying and the like. By adopting the method, the raw materials need to be pulverizedGrinding and processing of quartz type SiO2The activity is low, the dynamic hydrothermal synthesis process not only needs high liquid-solid ratio and long reaction time, so that the material consumption and the energy consumption are high, but also the generated xonotlite mineral fiber is short, and a large amount of unreacted quartz remains, so that the prepared heat-insulating material has high density and poor heat-insulating property.
Disclosure of Invention
The invention aims to realize high-value utilization of the fly ash, fully utilize amorphous silicon in the fly ash and prepare the ultra-light heat-insulating material.
In order to solve the technical problems, the invention provides a preparation method of an ultralight fibrous xonotlite type heat-insulating material based on extraction of amorphous silicon in fly ash, which comprises the following steps:
1) extracting amorphous silicon in the fly ash by a high-temperature high-pressure alkali dissolution method to obtain fly ash silicon extraction liquid;
2) taking the fly ash silicon extraction liquid obtained in the step 1) as a main siliceous raw material, taking lime milk as a main calcareous raw material, adding a crystal growth promoter, and preparing the ultralight fibrous xonotlite heat-insulating material by adopting a dynamic hydrothermal synthesis process.
Further, the specific steps of step 1) are as follows:
11) preparing a fly ash silicon extracting solution: preparing 10-30 wt% sodium hydroxide solution, and mixing SiO2Uniformly mixing pulverized coal furnace coal ash with the content of more than 30% and a sodium hydroxide solution according to the solid-to-liquid ratio of 1: 4-1: 2, placing the mixture into a high-pressure reaction kettle or a high-pressure sleeve heating container, and preserving heat for 0.5-3 h at the temperature of 100-150 ℃;
12) then carrying out solid-liquid separation on the reaction materials to obtain filtrate, adding clear water to the solid filtrate to enable the solid-liquid ratio to reach 1: 1.4-1: 1.7, carrying out countercurrent washing for 1-2 times, mixing the filtrate and the washing liquid, and heating and evaporating to enable Na in the mixed liquid2The concentration of O is 20-70 g/L, SiO2The concentration is 25-80 g/L, and the fly ash silicon extracting solution is obtained.
Further, the specific steps of step 2) are as follows:
21) synthesis of fibrous xonotlite: adding lime milk into the fly ash silicon extraction liquid obtained in the step 1) to ensure that the molar ratio of Ca/Si is 0.90-1.15, simultaneously adding a small amount of crystal growth promoter, adding water to adjust the mixture to be slurry with the solid-to-liquid ratio of 1: 10-1: 40, placing the slurry into a high-temperature high-pressure reaction kettle, firstly heating to 180-200 ℃ at the heating rate of 5-20 ℃/min, and keeping the temperature for 2-4 h at the stirring speed of 300-400 rpm; heating to 220-280 ℃ at a heating rate of 1-3 ℃/min, and keeping the temperature for 0.5-3 h under the condition of a stirring speed of 60-260 rpm to prepare fibrous xonotlite slurry;
22) recycling alkali liquor: step 21) cooling the fibrous xonotlite slurry prepared in the step to be below 80 ℃, discharging the fibrous xonotlite slurry from the kettle, dehydrating the fibrous xonotlite slurry in a filter pressing dehydration mode, and washing the fibrous xonotlite slurry with water at the temperature of 50-95 ℃ in a reverse direction for 2-5 times to finally obtain Na2Fibrous xonotlite having an O content of 1 to 6 wt%;
evaporating and concentrating the filter liquor after filter pressing and dehydration, then adding lime milk for causticization, adding a small amount of NaOH to enable the NaOH concentration of the filter liquor to reach 10-30 wt%, and circularly using the filter liquor in the step 1) for preparing the fly ash silicon extracting solution;
23) preparation of the heat insulating material: adding water into the washed fibrous xonotlite obtained in the step 22) to adjust the solid-to-liquid ratio to 1: 5-1: 20, adding 1.5-5% of fiber and about 0-3% of water glass with the modulus of 2-3.2, fully and uniformly stirring, injecting into a suction filtration dehydration press molding machine, and carrying under the pressure of 2-8 MPa for 0.5-3 min; and (3) standing the formed xonotlite type heat insulation product at 20-30 ℃ for more than 8 hours, then placing the product in a tunnel kiln at 50-150 ℃, and drying for 16-24 hours to control the water content to be less than 5%.
Further, the effective calcium content of the lime milk in the steps 21) and 22) is more than 80%, the activity index is more than 350ml, and the 120-mesh residue of the lime milk is less than 5%.
Further, the crystal growth promoter in the step 21) is ZrOCl2·8H2O and AlCl3Adding 20-40 g of ZrOCl into each cubic slurry2·8H2O and 50-100 g of AlCl3。
Further, the fiber in the step 23) is one or more of glass fiber, pulp fiber, carbon fiber, aramid fiber, ultra-high molecular weight polyethylene and recycled fiber.
The ultralight fibrous xonotlite type heat-insulating material based on the extraction of amorphous silicon in the fly ash is prepared according to the method.
Advantageous effects
The method for preparing the calcium silicate heat-insulating material by using the fly ash desiliconized material has the advantages of short reaction time, low energy consumption, cyclic utilization of alkali liquor and good product performance, and provides a new high-quality utilization way for the fly ash. Therefore, the invention has obvious social, economic and environmental benefits.
Drawings
FIG. 1 is a process flow diagram of the method for preparing the ultralight fibrous xonotlite-type thermal insulation material of the present invention.
Detailed Description
The present invention will be described in further detail with reference to specific examples.
The process flow of the invention is shown in figure 1. The invention takes fly ash silicon extracting liquid as main siliceous raw material, Si in the silicon extracting liquid is free [ H2SiO]4-Dissolving the form of anionic group in sodium hydroxide solution; lime milk as main calcium material, Ca is Ca (H)2O)5(OH)+The form of (A) is slightly soluble in water to form a suspension, and has the characteristic similar to colloid, so that the reaction of siliceous raw material and calcareous raw material is similar to liquid-liquid reaction, and the added crystal form promoter ZrOCl2·8H2O or AlCl3Can effectively promote the growth of the fibrous xonotlite and can generate the fibrous xonotlite crystal form with high length-diameter ratio. Compared with the traditional process, the technology reduces the equipment investment and ball milling energy consumption required by quartz sand powder milling, slightly reduces the hydrothermal synthesis temperature in the aspect of synthesis process, ensures that the synthesis reaction is more sufficient, greatly shortens the reaction time in the synthesis process from 6-12 h to 2.0-8 h, reduces the equipment investment of unit productivity, reduces the solid-liquid ratio required in the synthesis process from 1: 30-1: 50 to 1: 10-1: 40, obviously reduces the energy consumption, and prepares the xonotlite heat-insulating materialAll performance indexes are obviously improved, and particularly, the density of the product is reduced by more than 50 percent compared with the traditional process and is only 100kg/m3And about, the ultra-light level is achieved.
The first embodiment is as follows:
to SiO2Adding 32 wt% of fly ash into 15 wt% of sodium hydroxide solution to prepare slurry with a solid-to-liquid ratio of 1:4, placing the slurry in a high-pressure reaction kettle, carrying out silicon extraction reaction for 1.5h at the temperature of 120 ℃, carrying out solid-liquid separation on reaction products, adding clear water into solid filtrate to enable the solid-to-liquid ratio to reach 1:1.4, carrying out 2 times of countercurrent washing, mixing filtrate and washing liquid, heating and evaporating to prepare silicon extraction liquid, wherein Na in the silicon extraction liquid2O concentration of 62g/L, SiO2The concentration was 60 g/L. Adding lime milk (the content of available calcium is 86%, the activity index is 370ml, and the residue of a 120-mesh sieve is 3.2%) into the fly ash silicon extraction liquid to ensure that the Ca/Si (molar ratio) is 1.05, and simultaneously adding 23g of ZrOCl into each cubic of slurry2·8H2O and 70g of AlCl3Adding water to adjust the slurry to be a slurry with a solid-to-liquid ratio of 1:25, adding the slurry into a high-temperature high-pressure reaction kettle, heating to 190 ℃ at a heating rate of 5 ℃/min, keeping the temperature for 2.5h at a stirring speed of 300rpm, heating to 240 ℃ at a heating rate of 2 ℃/min, and keeping the temperature for 1.4h at a stirring speed of 130 rpm. After the heat preservation is finished, after the slurry in the kettle is cooled to be below 80 ℃, the slurry in the kettle is discharged, after the slurry is dehydrated by filter pressing, the filter cake is washed by water with the temperature of 70 ℃ for 3 times in a countercurrent way, and the length-diameter ratio of the filter cake is about 130, Na2Fibrous xonotlite with the O content of 3 wt%, and causticizing, concentrating and recycling after mixing the filtrate and the washing liquor. Adding water into fibrous xonotlite to adjust solid-liquid ratio to 1:12, adding 3.5% fiber (glass fiber: polyethylene: 7:3) and about 0.5% water glass with modulus of 2.0, stirring well, injecting into a suction filtration dehydration press molding machine, and holding under 4.3Mpa for 2.3 min. And (3) standing the molded heat-insulating product at 25 ℃ for 8h, then placing the heat-insulating product in a tunnel kiln at 120 ℃, and drying for 16h to obtain a heat-insulating material finished product. The density of the obtained fibrous xonotlite-type heat-insulating material was measured to be 123kg/m30.043W/(m.K) of heat conductivity coefficient at 100 ℃, 0.95MPa of compressive strength, 0.60MPa of flexural strength, 0.8 percent of linear shrinkage and 3.3 percent of water content,the maximum service temperature is 1000 ℃, and the fire resistance is grade A1, so that the requirements of III type products in GB/T10699-2015 calcium silicate heat insulation product standards are met.
Example two:
to SiO2Adding 35 wt% of fly ash into 20 wt% of sodium hydroxide solution to prepare slurry with a solid-to-liquid ratio of 1:3, placing the slurry in a high-pressure reaction kettle, carrying out silicon extraction reaction for 1.7h at the temperature of 135 ℃, carrying out solid-liquid separation on reaction products, adding clear water into solid filtrate to enable the solid-to-liquid ratio to reach 1:1.5, carrying out 2 times of countercurrent washing, mixing filtrate and washing liquid, heating and evaporating to prepare silicon extraction liquid, wherein Na in the silicon extraction liquid2O concentration of 63g/L, SiO2The concentration was 64 g/L. Adding lime milk (effective calcium content 84%, activity index 363ml, 120-mesh residue 2.7%) into fly ash silicon extraction liquid to make Ca/Si (molar ratio) 0.98, and simultaneously adding 30g ZrOCl into every cubic slurry2·8H2O and 65g of AlCl3Adding water to adjust the slurry to be a slurry with a solid-to-liquid ratio of 1:30, adding the slurry into a high-temperature high-pressure reaction kettle, heating to 200 ℃ at a heating rate of 7 ℃/min, keeping the temperature for 3.0h at a stirring speed of 280rpm, heating to 240 ℃ at a heating rate of 2 ℃/min, and keeping the temperature for 1.5h at a stirring speed of 110 rpm. After the heat preservation is finished, after the slurry in the kettle is cooled to be below 80 ℃, the slurry in the kettle is discharged, after the slurry is dehydrated by filter pressing, the filter cake is washed by water with the temperature of 75 ℃ for 3 times in a countercurrent way, and the length-diameter ratio of the filter cake is about 140, Na2Fibrous xonotlite with an O content of 2.8 wt%, and causticizing, concentrating and recycling after mixing the filtrate and the washing liquor. Adding water into fibrous xonotlite to adjust solid-liquid ratio to 1:15, adding 5% fiber (glass fiber: pulp fiber: polyethylene: 5:2:3) and about 0.4% water glass with modulus of 2.3, stirring well, injecting into suction filtration dehydration press molding machine, and holding under 2.6Mpa for 2.0 min. And (3) standing the molded heat-insulating product at 25 ℃ for 8h, then placing the heat-insulating product in a tunnel kiln at 135 ℃, and drying for 20h to obtain a heat-insulating material finished product. The density of the obtained fibrous xonotlite-type heat-insulating material is 118kg/m3The heat conductivity coefficient at 100 ℃ is 0.041W/(m.K), the compressive strength is 0.83MPa, the breaking strength is 0.47MPa, the linear shrinkage rate is 1.1 percent, the water content is 2.8 percent, and the highest rate isThe service temperature is 1000 ℃, and the fireproof performance is grade A1, so that the requirements of III type products in GB/T10699-2015 calcium silicate heat insulation product standards are met.
Example three:
to SiO2Adding fly ash with the content of 37 wt% into 22 wt% of sodium hydroxide solution to prepare slurry with the solid-to-liquid ratio of 1:4, placing the slurry in a high-pressure reaction kettle to perform silicon extraction reaction for 2.1 hours at the temperature of 150 ℃, performing solid-liquid separation on a reaction product, adding clear water into a solid filtrate to enable the solid-to-liquid ratio to reach 1:1.5, performing countercurrent washing for 2 times, mixing the filtrate and the washing solution, heating and evaporating to prepare silicon extraction liquid, and adding Na in the silicon extraction liquid2O concentration of 75g/L, SiO2The concentration was 62 g/L. Adding lime milk (the content of effective calcium is 87%, the activity index is 376ml, and the residue of a 120-mesh sieve is 3.4%) into the fly ash silicon extraction liquid to ensure that the Ca/Si (molar ratio) is 1.0, and simultaneously adding 35g of ZrOCl into each cubic of slurry2·8H2O and 85g of AlCl3Adding water to adjust the slurry to be a slurry with a solid-to-liquid ratio of 1:30, adding the slurry into a high-temperature high-pressure reaction kettle, heating to 200 ℃ at a heating rate of 6 ℃/min, keeping the temperature for 3.5h at a stirring speed of 260rpm, heating to 260 ℃ at a heating rate of 2 ℃/min, and keeping the temperature for 2.0h at a stirring speed of 110 rpm. After the heat preservation is finished, after the slurry in the kettle is cooled to be below 80 ℃, the slurry in the kettle is discharged, after the slurry is dehydrated by filter pressing, the filter cake is washed by water with the temperature of 70 ℃ for 3 times in a countercurrent way, and the length-diameter ratio of the filter cake is about 150, Na2Fibrous xonotlite with an O content of 3.2 wt%, and causticizing, concentrating and recycling after mixing the filtrate and the washing liquor. Adding water into fibrous xonotlite to adjust solid-liquid ratio to 1:20, adding 5% fiber (glass fiber: pulp fiber: polyethylene: 6:2:2) and about 0.4% water glass with modulus of 2.3, stirring well, injecting into a suction filtration dehydration press molding machine, and holding under 2.4Mpa for 1.7 min. And (3) standing the molded heat-insulating product at 25 ℃ for 8h, then placing the heat-insulating product in a tunnel kiln at 135 ℃, and drying for 22h to obtain a heat-insulating material finished product. The density of the fibrous xonotlite-type heat-insulating material prepared by detection is 97kg/m3The heat conductivity coefficient at 100 ℃ is 0.038W/(m.K), the compressive strength is 0.78MPa, the breaking strength is 0.43MPa, the linear shrinkage rate is 1.5 percent, the water content is 2.6 percent, and the highest use temperature isThe temperature is 1000 ℃, and the fireproof performance is grade A1, which meets the requirements of III type products in GB/T10699-2015 calcium silicate heat insulation product standard.
Claims (7)
1. A preparation method of an ultralight fibrous xonotlite type heat-insulating material based on extraction of amorphous silicon in fly ash is characterized by comprising the following steps:
1) extracting amorphous silicon in the fly ash by a high-temperature high-pressure alkali dissolution method to obtain fly ash silicon extraction liquid;
2) taking the fly ash silicon extraction liquid obtained in the step 1) as a main siliceous raw material, taking lime milk as a main calcareous raw material, adding a crystal growth promoter, and preparing the ultralight fibrous xonotlite heat-insulating material by adopting a dynamic hydrothermal synthesis process.
2. The preparation method according to claim 1, wherein the specific steps of the step 1) are as follows:
11) preparing a fly ash silicon extracting solution: preparing 10-30 wt% sodium hydroxide solution, and mixing SiO2Uniformly mixing pulverized coal furnace coal ash with the content of more than 30% and a sodium hydroxide solution according to the solid-to-liquid ratio of 1: 4-1: 2, placing the mixture into a high-pressure reaction kettle or a high-pressure sleeve heating container, and preserving heat for 0.5-3 h at the temperature of 100-150 ℃;
12) then carrying out solid-liquid separation on the reaction materials to obtain filtrate, adding clear water to the solid filtrate to enable the solid-liquid ratio to reach 1: 1.4-1: 1.7, carrying out countercurrent washing for 1-2 times, mixing the filtrate and the washing liquid, and heating and evaporating to enable Na in the mixed liquid2The concentration of O is 20-70 g/L, SiO2The concentration is 25-80 g/L, and the fly ash silicon extracting solution is obtained.
3. The preparation method according to claim 1, wherein the step 2) comprises the following specific steps:
21) synthesis of fibrous xonotlite: adding lime milk into the fly ash silicon extraction liquid obtained in the step 1) to ensure that the molar ratio of Ca/Si is 0.90-1.15, simultaneously adding a small amount of crystal growth promoter, adding water to adjust the mixture to be slurry with the solid-to-liquid ratio of 1: 10-1: 40, placing the slurry into a high-temperature high-pressure reaction kettle, firstly heating to 180-200 ℃ at the heating rate of 5-20 ℃/min, and keeping the temperature for 2-4 h at the stirring speed of 300-400 rpm; heating to 220-280 ℃ at a heating rate of 1-3 ℃/min, and keeping the temperature for 0.5-3 h under the condition of a stirring speed of 60-260 rpm to prepare fibrous xonotlite slurry;
22) recycling alkali liquor: step 21) cooling the fibrous xonotlite slurry prepared in the step to be below 80 ℃, discharging the fibrous xonotlite slurry from the kettle, dehydrating the fibrous xonotlite slurry in a filter pressing dehydration mode, and washing the fibrous xonotlite slurry with water at the temperature of 50-95 ℃ in a reverse direction for 2-5 times to finally obtain Na2Fibrous xonotlite having an O content of 1 to 6 wt%;
evaporating and concentrating the filter liquor after filter pressing and dehydration, then adding lime milk for causticization, adding a small amount of NaOH to enable the NaOH concentration of the filter liquor to reach 10-30 wt%, and circularly using the filter liquor in the step 1) for preparing the fly ash silicon extracting solution;
23) preparation of the heat insulating material: adding water into the washed fibrous xonotlite obtained in the step 22) to adjust the solid-to-liquid ratio to 1: 5-1: 20, adding 1.5-5% of fiber and about 0-3% of water glass with the modulus of 2-3.2, fully and uniformly stirring, injecting into a suction filtration dehydration press molding machine, and carrying under the pressure of 2-8 MPa for 0.5-3 min; and (3) standing the formed xonotlite type heat insulation product at 20-30 ℃ for more than 8 hours, then placing the product in a tunnel kiln at 50-150 ℃, and drying for 16-24 hours to control the water content to be less than 5%.
4. The preparation method of claim 3, wherein the effective calcium content of the lime milk in the steps 21) and 22) is more than 80%, the activity index is more than 350ml, and the 120-mesh residue of the lime milk is less than 5%.
5. The method according to claim 3, wherein the crystal growth promoter of step 21) comprises ZrOCl2·8H2O and AlCl3Adding 20-40 g of ZrOCl into each cubic slurry2·8H2O and 50-100 g of AlCl3。
6. The method of claim 3, wherein the fiber of step 23) is one or more of a glass fiber, a pulp fiber, a carbon fiber, an aramid fiber, an ultra-high molecular weight polyethylene, and a recycled fiber.
7. An ultra-light fibrous xonotlite-type insulation material based on extraction of amorphous silicon from fly ash, prepared by the method of any one of claims 1 to 6.
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