CN113511666A - Zero-dimensional and one-dimensional calcium sulfate-based micro-nano composite product and composite material prepared from cement and three wastes as raw materials and synthesis process - Google Patents
Zero-dimensional and one-dimensional calcium sulfate-based micro-nano composite product and composite material prepared from cement and three wastes as raw materials and synthesis process Download PDFInfo
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Abstract
The invention provides a zero-dimensional and one-dimensional calcium sulfate-based micro-nano composite product and a composite material produced by using cement as a raw material to promote flue gas, waste sulfuric acid or ammonium sulfate to be recycled, and a novel process method. Application evaluation results show that the new composite product has the advantages of remarkably improving the early strength performance of concrete, basically maintaining the tensile strength, bending strength and impact toughness of composite materials such as plastics and the like under the condition of large-proportion addition, enhancing the bonding force of adhesives and the like, improving the quality and reducing the cost performance, and has great development and application potentials.
Description
Technical Field
The invention relates to a zero-dimensional or/and one-dimensional calcium sulfate-based micro-nano composite product produced by using cement as a raw material and using three wastes and a sulfur-containing compound raw material, a preparation method and application thereof, belonging to the technical field of new material production.
Background
The micro-nano material refers to a material with the size between the micron level and the nanometer level, and is a general name of the micron material and the nanometer material. It is generally internationally accepted that the size of the micron material is in the range of 1 μm to 100 μm; the size of the submicron-scale material is between 100nm and 1 μm; nanomaterials are materials that are less than 100nm in size in any of the three dimensions of space. In recent years, micro-nano materials show great application potential in the aspect of improving the performance of composite materials, and various high-performance plastics, rubber and other composite materials are continuously developed.
Natural cement is formed by volcanic eruptions, first discovered one thousand two million years ago. Synthetic cements began the industrial revolution (around 1800 years) and the most common Portland Cement is also known as Portland Cement (Portland Cement). The industrial production process is that limestone (calcium carbonate), sandy soil (silicon dioxide, aluminate) and other raw materials rich in calcium silicate and coal are calcined and melted in a kiln at 1450 ℃ to generate tricalcium silicate as a main component, and molten mass containing aluminate, ferroaluminate and other components, called as 'clinker', the molten mass clinker obtained by cooling the molten mass is mixed with 15-30% of limestone or granulated blast furnace slag and 5% of gypsum and ground to obtain gray or white powder cement products, the high-temperature flue gas heat generated in the cement melting and burning process is used for power generation, and the flue gas after dust removal and purification can reach the standard and be discharged. The cement raw materials are simple and easy to obtain, the production process is advanced, and the energy is fully utilized, so that the production cost of the cement is only about 200 yuan/ton, the selling price is always about 400 yuan/ton, the huge market demand and high cost performance promote the rapid development of the cement industry, the cement becomes an industrial product with the maximum capacity, the global yield of the cement is close to 40 hundred million tons, and the Chinese cement yield accounts for 60 percent of the world.
The main component of portland cement clinker is tricalcium silicate (Ca)3SiO5) And dicalcium silicate (Ca)2SiO4) The cross-linked inorganic reticular polymer is a soluble component with strong alkalinity and reactivity, is hydrated and condensed with water, weak acid and strong acid to generate cross-linked inorganic reticular polymer, and is a chemical bonding basis of the key bonding component of concrete. However, the cement used as a filler directly applied to a synthetic material has the problems of difficult dispersion, easy agglomeration and poor stability, and the application expansion is also influenced by the easy moisture absorption and agglomeration. Thus, the only use of cement as a binder in concrete is the use of portland cement only for the production of concrete building materials with aggregate (sand and gravel) and water. People develop building materials by utilizing the hydraulic cementing and bonding effect of a cross-chain type inorganic reticular polymer generated by the hydration condensation reaction of cement for more than two hundred years, but the improvement of the workability and the strength of the concrete mortar cannot be solved.
1 ton of carbon dioxide is produced as a byproduct in each ton of cement, and the emission of dust and pollutants is large, so that a large number of cement plants in China are forced to be shut down. The ultra-low emission of pollutants in flue gas is promoted, simultaneously, cheap and rich cement and water are used as basic raw materials, large-scale and low-cost production processes and synthesis equipment systems of series of micro-nano materials such as calcium silicate and white carbon black are fully developed, a green high-cost-performance composite material is further developed, and the strategic requirements of global sustainable development are met.
Therefore, based on the advantages of large cement production capacity, guaranteed raw materials and low cost, the characteristics of good product fineness, strong basicity, calcium enrichment and silicon enrichment and solubility are utilized, reactions of hydration, carbonization, acid-base neutralization, precipitation, double decomposition and the like of the cement raw materials can be fully utilized, waste three wastes resources are combined, the development performance is stable, the cost is low, and the method is valuable for developing micro-nano material series with various shapes in different application scenes and wide fields, and has great significance for constructing an industrial group and a micro-nano material library taking cement as a leading part, promoting the upgrading and updating of products in the material industry and optimizing the structure.
Calcium sulfate can be divided into crystal forms such as whisker-shaped, sheet-shaped and spindle-shaped crystals according to the appearance of the calcium sulfate, the crystal forms mostly exist in nature in the form of gypsum ore, and a large amount of industrial gypsum generated in phosphate fertilizer production, flue gas desulfurization, waste sulfuric acid neutralization and hydrogen fluoride production is not well utilized.
Calcium sulfate generally contains two molecules of crystal water (CaSO)4·2H2O), commonly known as gypsum, of which Ca is present2+And SO4 2-A double-layered structure is formed, between which water molecules and Ca2+The gypsum has small hardness, low strength, poor heat resistance and low use value; calcium sulfate hemihydrate CaSO formed by gypsum losing part of crystal water at 128 DEG C4·0.5H2O, commonly known as 'calcined gypsum' or 'calcined gypsum', has better application value; the gypsum can be completely dehydrated into anhydrous CaSO only at the temperature of more than 163 DEG C4Commonly called anhydrite, has short inter-atomic distance inside, tight connection, better stability and high temperature resistance, and the melting point is as high as 1450 ℃.
Besides being used as a gypsum board raw material and a cement retarder, gypsum or calcium sulfate has limited use. Researches find that the calcium sulfate can form fibrous crystals (whiskers), the length-diameter ratio can reach 10-1000, and the fibrous crystals (whiskers) have the characteristics of small diameter, large length-diameter ratio, high modulus, high strength, high elongation, good thermal stability, chemical corrosion resistance, good compatibility with plastics and the like, and the tensile strength of the calcium sulfate whiskers is 5-10 times of that of glass fibers, so that the fibrous crystals (whiskers) are reinforcing materials with development potential.
At present, the synthesis process of calcium sulfate whisker mainly uses natural gypsum to prepare calcium sulfate hemihydrate or anhydrous calcium sulfate by a hydrothermal method. The research and development group has invented a new process for preparing modified and unmodified calcium sulfate whiskers in an alcohol-water system (application No. 201910256421.3). As a large amount of gypsum or waste sulfuric acid or mirabilite and other sulfides are generated as byproducts in phosphate fertilizer plants, titanium dioxide plants, citric acid plants, coal-fired power plants, flue gas desulfurization plants, fluorination plants, salt and alkali plants, seawater salt-making enterprises and the like, the development of high-quality nano calcium sulfate or calcium sulfate whiskers has application value if waste sulfuric acid, sulfate and other three-waste resources and cheap cement are used as raw materials.
Disclosure of Invention
The invention successfully develops a zero-dimensional and/or one-dimensional calcium sulfate-based micro-nano compound product produced by using cement as a raw material and utilizing three wastes and sulfide resources, and expands a micro-nano raw material library.
We have found by X-ray diffractometry that the hydration and neutralization processes of cement clinker: calcium silicate in cement clinker can directly undergo neutralization and hydration reaction to generate a mixture of calcium sulfate, hydrated calcium silicate and calcium hydroxide, raw materials and hydrate are easy to undergo neutralization and precipitation reaction with sulfur dioxide, sulfuric acid, ammonium sulfate and other Lewis acids to generate silica gel and calcium sulfate compounds, silica gel macromolecules can be quickly dehydrated on the surfaces of gypsum crystals at the temperature of about 80 ℃ to form membranous or granular white carbon black, and the product has large specific surface area and good service performance. Through researches on double decomposition, hydration, neutralization and silica gel dehydration condensation rules of portland cement, optimized synthesis process conditions are developed, a novel micro-nano compound product of calcium sulfate block/sheet/rod/whisker attached nano white carbon black and a small amount of ferric oxide and aluminum oxide with stable performance and high cost performance is successfully synthesized, and product characterization and application performance evaluation results prove that: the calcium sulfate/nano white carbon black compound has better dispersion and application effects than common nano calcium carbonate, white carbon black, titanium dioxide and calcium sulfate whiskers, can basically maintain or improve the tensile strength, bending strength and impact toughness of a composite material when being added into the composite materials such as plastics in a large proportion, can obviously enhance the peeling strength of the polyurethane artificial leather and the adhesive force of an adhesive, and has obvious cost performance improvement advantages.
The invention heats and hydrates common silicate or silicate cement clinker and water or water-organic solvent mixed solution with optimized quantity at a certain temperature, simultaneously introduces flue gas containing sulfur dioxide or adds sulfuric acid, or adds ammonium sulfate to neutralize and simultaneously recovers ammonia, also can simultaneously add modifier or macromolecular modifier to control crystal form and morphology, in optimized proportion, reaction and crystallization temperature, time and solvent system, filters and washes according to conventional method, and dries at higher temperature to obtain series micro-nano inorganic composite products.
In conclusion, the invention creates a new way for producing the high-performance micro-nano new material in a large scale and at low cost by using cement as a raw material, has great significance for utilizing the three wastes (waste gas, waste sulfuric acid, waste gypsum and the like) resources with high added values and developing the high-cost-performance composite new material in a large scale.
Specifically, the invention provides a zero-dimensional and/or one-dimensional calcium sulfate-based micro-nano composite product, wherein the zero-dimensional and/or one-dimensional calcium sulfate-based micro-nano composite product comprises: the preparation method of the compound of the calcium sulfate block/sheet/rod/whisker and the nano white carbon black comprises the following steps:
adding the mixture of cement and/or cement clinker and lime into a water-containing system, adding a sulfur compound raw material at 0-100 ℃, stirring and mixing, and carrying out double decomposition, hydration, neutralization and dehydration condensation reaction for 0.5-10h to synthesize the zero-dimension and/or one-dimension calcium sulfate-based micro-nano composite product. The product form is preferably one-dimensional calcium sulfate whisker/white carbon black composite.
The sulfur compound raw material is selected from one or more of sulfuric acid, ammonium sulfate, ammonium sulfite, flue gas needing desulfurization, sulfur dioxide, sulfur trioxide or waste sulfuric acid.
Preferably, the cement is selected from the group consisting of portland cement, aluminosilicate cement; the cement clinker is preferably portland cement clinker.
Preferably, the reaction temperature is 25-80 ℃, and the reaction time is 2-8 h; preferably, the reaction temperature is 25-60 ℃ and the reaction time is 2-6 h. For the one-dimensional calcium sulfate whisker/nano white carbon black product, the reaction time is preferably 4-8 h. Preferably, the end point of the neutralization reaction is at a pH of 6-8, or the reaction can be stopped at any stage at a pH greater than 7.
Preferably, the mass of water in the reaction is at least two times, preferably 2-5 times, that of the solid starting material.
Preferably, the aqueous system is selected from water, a mixed system of water and an organic solvent, an aqueous solution added with a modifier, or a mixed system of water and an organic solvent added with a modifier; for the one-dimensional calcium sulfate whisker/nano white carbon black product, preferably, the organic solvent is selected from alcohols of C1-C4 and DMF; the volume ratio of water to organic solvent is 0.2-5.0: 1; the modifier is solid or liquid, and the mass ratio of the cement raw material to the modifier is 10-1000: 1.
Preferably, the modifier is a small molecule modifier or a high molecule modifier; preferably, the small molecular modifier is stearic acid or stearate, the high molecular modifier is a water-soluble high molecular modifier or a high molecular modifier capable of forming emulsion, and preferably one or more of styrene-acrylic emulsion, sodium lignin, acrylic emulsion, silicone acrylic emulsion, fluorine acrylic emulsion, polyvinyl alcohol, polyethylene glycol, urea-formaldehyde resin, phenolic resin and bio-based sulfonate; preferably, the biobased sulfonate is a lignosulfonate or a cellulose sulfonate.
Preferably, after the reaction is finished, the method further comprises the steps of filtering, washing and drying the reaction mixture. The washing solvent is water or ethanol, the drying temperature is 100-200 ℃, and the drying time is 0.5-24 h.
Further, the invention provides the application field of the calcium sulfate-based micro-nano composite product, wherein the calcium sulfate-based micro-nano composite product is used for reducing cost and improving quality of synthetic materials, natural materials and composite materials; preferably, the synthetic material, natural material or composite material is plastic, rubber, paint, cement, asphalt, sealant, ink, adhesive or paper; more preferably, the calcium sulfate-based micro-nano composite product is added to the synthetic material, the natural material or the composite material separately, or the calcium sulfate-based micro-nano composite product and other nano materials are added to the synthetic material, the natural material or the composite material in combination.
Preferably, the calcium sulfate-based micro-nano composite product is used for improving the tensile strength, the impact toughness and the processing performance of plastics and rubber, is used for improving the peel strength of polyurethane leather, is used for improving the bonding strength and the water resistance of a binder, or is used for improving the softening point, the penetration degree and the rutting resistance of asphalt.
The invention also provides a reinforcing material which comprises the micro-nano composite product and any one of a synthetic material, a natural material and a composite material.
The invention also provides a new method for regenerating ammonia, which comprises the following steps:
in the preparation method of the micro-nano compound product, a calcium-based raw material containing cement is subjected to neutralization reaction, an industrial byproduct ammonium sulfate is used as a raw material for neutralization, the pH value is controlled to be more than or equal to 7 at the end point of the neutralization reaction, and ammonia gas is recovered during the neutralization reaction.
The reaction equation in the preparation method of the micro-nano composite product is as follows:
3CaOgSiO2+(3-m+n)H2O→mCaOgSiO2gnH2O+(3-n)Ca(OH)2
2CaOgSiO2+(2-m+n)H2O→mCaOgSiO2gnH2O+(2-m)Ca(OH)2
3CaOgAl2O3+6H2O→3CaOgAl2O3g6H2O
4CaOgAl2O3gFe2O3+7H2O→3CaOgAl2O3gFe2O3g6H2O+Ca(OH)2
Ca(OH)2+SO4 2-+yH2O→CaSO4·yH2O+2OH-
CaO·SiO2+H2SO4+(x+y)H2O→H2SiO3·xH2O+CaSO4·yH2O
CaO·SiO2+(NH4)2SO4+(x+y)H2O→SiO2·(x+1)H2O+CaSO4·yH2O+NH3
SiO2·xH2O→SiO2+xH2O
the process trace shows that: along with the reaction, dihydrate, calcium sulfate hemihydrate and amorphous nano white carbon black can be detected, the prepared calcium sulfate can be in a whisker, sheet or block structure, and the crystal form of the product is mainly calcium sulfate hemihydrate after the product is completely dried at the temperature of 100-200 ℃. After the product is completely dried, the amount of the product is increased by about 40% relative to the cement raw material (see fig. 1-10).
The product of the invention is carried out according to the conventional plastic filler detection and evaluation method, and comprises the following steps:
step (1): weighing 100 parts of plastic and adding different parts of micro-nano composite products for fully mixing;
step (2): and (2) adding the mixed material obtained in the step (1) into an internal mixer, and carrying out melt extrusion, granulation, cooling and drying to obtain a composite material finished product. Wherein the temperature of the extruder barrel is 180-200 ℃, the screw rotating speed is 30-40 r/min, and the melting mixing stirring time is 15 min.
The product of the invention is carried out according to a conventional concrete detection and evaluation method, and comprises the following steps:
step (1): weighing 100 parts of cement clinker and micro-nano compound products with different qualities, and fully mixing;
step (2): weighing water with different qualities according to a certain water-cement ratio, adding the water into the mixture obtained in the step (1), and fully mixing the water and the mixture by a planetary mixer;
and (3): and (3) placing the mixture obtained in the step (2) into a test mould with the thickness of 20mm multiplied by 20mm, carrying out standard maintenance for 24 hours, disassembling the mould, and continuing the standard maintenance to the age to obtain a sample strip for testing the concrete.
Wherein the water cement ratio is 0.27-0.31, and the standard curing condition refers to that the test block is cured in an environment with the temperature of 20 + -3 ℃ and the relative humidity of more than 90 percent, and the age is 3 days, 7 days and 28 days.
The product of the invention is carried out according to a conventional binder detection and evaluation method, and comprises the following steps:
step (1): grinding the micro-nano compound product, sieving with a 200-mesh sieve, adding 5%, 10% and 30% of the micro-nano compound product into styrene-acrylic emulsion respectively to prepare compound adhesive
And (3) calculating the mixture ratio:
(x is the mass of the product, y is the mass of the emulsion, z is the solid content of the emulsion, and n is 5%, 10% or 30%);
step (2): cutting bamboo strips into segments (length is 10cm), washing with water, naturally drying in the air, and drying in an oven at 63 deg.C for 24 h;
and (3): gluing the thin bamboo sheet, drying in an oven at 63 deg.C for 2min (slightly curing), hot pressing at 100-180 deg.C under 10-25 MPa for 5-10 min, and standing for one day;
and (4): testing the tensile strength of the sample strips by using a universal mechanical testing machine, and testing 5 samples (averaging results);
and (5): and (3) respectively carrying out water bath at 63 ℃ for 3h and water bath at 100 ℃ for 8h to carry out water resistance test, observing and recording the change of the bonding condition of the sample strips after the test is finished, and testing 4 samples in each group.
The invention has the following beneficial effects:
the invention has the advantages of abundant, cheap and easily obtained raw materials, realization of recycling of 'three wastes', simple process, good product application performance, wide application range, large-scale, low cost, clean production and the like.
The bright spot of the invention is a new product of modified and unmodified micro-nano composite which takes cheap portland cement and 'three wastes' as raw materials to produce high-performance calcium sulfate whisker as main components at low cost, and has better reinforcing and toughening performance.
The zero-dimensional or/and one-dimensional calcium sulfate-based micro-nano composite product synthesized by the invention can be widely applied to plastics, rubber, coatings, cement, asphalt, sealants, printing ink, adhesives, paper or composite materials in a large proportion, a new composite material with higher cost performance is developed, and the effects of strengthening and toughening or basically maintaining the strength after large-proportion addition are achieved.
Drawings
Fig. 1 and 2 show XRD and SEM tracking results of calcium sulfate preparation from cement under different conditions in example 1.
Fig. 3 and 4 are XRD and SEM tracking results of the calcium sulfate micro-nano composite product prepared in the alcohol/water mixed solvent in example 2.
Fig. 5 and 6 are XRD and SEM characterization results of calcium sulfate micro-nano composite product prepared by adding different modification aids in example 3.
Fig. 7 and 8 are XRD and SEM tracking results of calcium sulfate micro-nano composite product prepared by using portland cement and ammonium sulfate as raw materials in example 4.
FIG. 9-1, FIG. 9-2, FIG. 10-1, and FIG. 10-2 are XRD and SEM tracking analysis results of calcium sulfate micro-nano composite products prepared from cement clinker under different drying conditions in example 5.
Detailed Description
The present invention is further illustrated by the following specific examples. The raw materials and equipment used in the examples were:
PC32.5R cement, PO42.5R cement, cement clinker: anhui conch Cement Ltd;
sulfuric acid, ammonium sulfate: the purity of the chemical reagent of the national medicine group is more than or equal to 99.5 percent;
e01 styrene-acrylic emulsion, namely styrene-acrylic emulsion: beijing violet-light England Chemicals technology, Inc., 50% aqueous emulsion;
solid sodium lignin: beijing violet ray chemical technology, Inc., pulping by-product;
polypropylene resin: ningbo Fude energy Co., Ltd;
circulating water type vacuum pump: schoever City Zernike Limited responsibility company, SHZ- (III)
Heat collection type constant temperature heating magnetic stirrer: DF-101S, Chengxihua Limited company;
an electronic balance: sydows scientific instruments ltd, BS 224S;
and (3) vacuum drying oven: steve City Prov. Limited, DZF-6020;
shanghai scientific internal mixer: LH 200;
ningbo Haitian injection molding machine: SA 600/150;
microcomputer controlled electronic universal tester: AGS-X, 10N-10kN +250 mm;
mertese pendulum impact tester: ZBC 7251-B;
mertess melt flow rate tester: ZRZ 1452;
cement paste mixer: tin-free Instrument machinery, Inc., NJ-160;
the microcomputer controlled full-automatic cement pressure testing machine: jinan Mei Te Tech test technology, Inc., YAW-300C;
a kneader: lezhou gray machinery ltd, electric heating type;
full-well analysis: TriStar model II 3020 full-automatic specific surface and pore Analyzer, Michkok instruments, USA;
x-ray diffractometer: japanese science MiniFlex 600;
scanning electron microscope: zeiss SIGMA300, germany.
The technical scheme of the invention is further illustrated by combining specific examples. These examples are intended to illustrate the invention and are not intended to limit the scope of the invention.
Examples
Example 1: composite Portland cement and sulfuric acid are used as raw materials, and micro-nano composite products are prepared under different conditions
Adding 10g of PC32.5R cement into 100mL of water, respectively dripping 0.01mol, 0.03mol, 0.05mol, 0.07mol and 0.09mol of sulfuric acid, after the reaction is finished under the conditions shown in Table 1, carrying out suction filtration, washing with ethanol, and drying at 105 ℃ for 8 hours to obtain the product.
TABLE 1 results of cement treatment with sulfuric acid under different conditions
Fig. 1, fig. 2 and table 1 show XRD and SEM tracking results of calcium sulfate preparation from cement under different conditions of example 1, and it can be seen that as the addition amount of sulfuric acid increases, cement gradually hydrates and decomposes and undergoes neutralization reaction with sulfuric acid to generate calcium sulfate, and when the amount of acid is insufficient, calcium silicate hydrate and calcium carbonate still remain in the product; when the pH value of the system is reduced to about 5, a calcium sulfate dihydrate product and white carbon black are mainly generated, and the generated calcium sulfate dihydrate is dehydrated at 105 ℃ for more than 8 hours to generate calcium sulfate hemihydrate with gullies distributed on the surface (powdered), wherein the grain diameter of the powdered calcium sulfate hemihydrate can reach the nanometer level (see example 5 for crystal form change in the drying process). The crystal form appearance of the product is not changed greatly when the reaction temperature is increased. Reacting at 25 deg.c for 2 hr to obtain product with small amount of un-reacted tricalcium silicate and dicalcium silicate, and reacting for over 4 hr to obtain tricalcium silicate and dicalcium silicate.
Example 2: preparing micro-nano compound product in alcohol/water solvent system by taking portland cement and sulfuric acid as raw materials
Adding 25g PC32.5R Portland cement into 100mL ethanol solvent, and mechanically stirring uniformly; the solution was slowly added to the portland cement suspension obtained in the previous step, and after 4 hours of reaction with stirring at room temperature, the solution was suction-filtered, washed with water, and dried at 180 ℃ for 1 hour, whereby 34.7g, 35.4g, 35.7g, 35.9g, and 36.3g of products were obtained.
Table 2 results of whole-well analysis of raw materials and products in examples
Fig. 3, fig. 4 and table 2 show XRD and SEM traces of calcium sulfate micro-nano composite products prepared in alcohol/water mixed solvent and full-pore analysis results of the products in example 2, and it can be seen that portland cement and sulfuric acid in an alcohol/water mixed system react to tend to generate micron-sized rod-like calcium sulfate, the main component after drying is calcium sulfate hemihydrate, the use amount of sulfuric acid has an obvious effect on the morphology of the products, a rod-like structure with a larger major diameter is obtained when 0.175mol of sulfuric acid is added, and a thicker short rod is generated after the amount of sulfuric acid is increased. The results of the full-pore analysis show that the specific surface and pore volume of the product after the reaction with sulfuric acid are greatly increased compared with those of the raw material.
Example 3: portland cement and sulfuric acid are used as raw materials, different modification aids are added to prepare a micro-nano compound product
Adding 25g of PC32.5R cement into 100mL of water or ethanol, then dripping 100mL of aqueous solution containing 0.225mol (water solvent) or 0.175mol (alcohol-water solvent) of sulfuric acid, adding the auxiliary agent shown in the table 3, stirring at 25 ℃ for reaction for 4h, then carrying out suction filtration, washing with water, and drying at 180 ℃ for 1h to obtain the product.
TABLE 3 results of cement treatment with sulfuric acid under different conditions
(note: wherein, the emulsion is E01 styrene-acrylic emulsion)
Fig. 5, fig. 6 and table 3 show XRD and SEM characterization results of calcium sulfate micro-nano composite products prepared by adding different modification aids in example 3, and it is found that the addition of emulsion and stearic acid has little influence on the morphology and crystal form of the products, the water system mainly generates massive calcium sulfate, and the alcohol-water system generates rod-like calcium sulfate.
Example 4: preparation of micro-nano composite product by using portland cement and ammonium sulfate as raw materials and mixed solvent system
Adding three parts of 24g PC32.5R Portland cement into 100mL of water, 100mL of ethanol solvent and 100mL of DMMF solvent respectively, and mechanically stirring uniformly; dissolving three parts of 26.4g of ammonium sulfate in 100mL of water to prepare an ammonium sulfate solution, slowly adding the ammonium sulfate solution into the three kinds of portland cement suspension, stirring and reacting for 4 hours at room temperature, filtering, washing with water, and drying for 1 hour at 180 ℃ to obtain 33.8g, 33.4g and 34.1g of products.
Table 4 results of whole-well analysis of raw materials and products in examples
Fig. 7, fig. 8 and table 4 show XRD and SEM of the calcium sulfate micro-nano composite product prepared by using portland cement and ammonium sulfate as raw materials and the full pore analysis results of the material in example 4, and the analysis results show that ammonium sulfate and cement mainly generate massive calcium sulfate in a water solvent system, while ammonium sulfate and cement mainly generate calcium sulfate whiskers in ethanol/water, DMF/water systems, which shows that the product obtained by reaction using ammonium sulfate as a raw material is very similar to the product obtained by using sulfuric acid as a raw material, and the specific surface and pore volume obtained by the full pore analysis are relatively close.
Example 5: preparation of micro-nano composite product by using portland cement clinker and sulfuric acid as raw materials under different drying conditions
Adding 25g of portland cement clinker into 100mL of water, and mechanically stirring uniformly; diluting 0.225mol of sulfuric acid in 100mL of water to prepare a dilute sulfuric acid solution, slowly adding the solution into the cement clinker suspension obtained in the previous step, stirring and reacting for 4 hours at room temperature, and then carrying out suction filtration without washing to obtain a filter cake. The products obtained by drying at room temperature (25 ℃), 105 ℃, 125 ℃, 145 ℃ and 185 ℃ for various times were analyzed.
9-1, 9-2, 10-1, and 10-2 are XRD and SEM trace analysis results of calcium sulfate micro-nano composite products prepared by cement clinker under different drying conditions in example 5, and it can be seen that the reaction product of cement clinker and sulfuric acid at room temperature is sheet calcium sulfate dihydrate, calcium sulfate dihydrate is gradually dehydrated to generate calcium sulfate hemihydrate at 105 ℃ along with the extension of drying time, the calcium sulfate hemihydrate is substantially completely converted within 8 hours, the sheet structure is gradually pulverized to form a block structure, the conversion time is shortened along with the increase of drying temperature, the conversion time is substantially completely converted at 125 ℃ for 4 hours, the conversion is substantially completely converted at 145 ℃ for 2 hours, the conversion is substantially completely converted after 185 ℃ for 1 hour, and the obtained product quality is 35.65g (105 ℃/8 hours), 34.87g (125 ℃/4 hours), 34.94g (145 ℃/2 hours), respectively, 35.07g (185 ℃/1h), the quality of the obtained 100g cement is basically kept at 140g after the product is completely converted into calcium sulfate hemihydrate, and the quality is considerable. It can be seen that the temperature and time range for the conversion of calcium sulfate dihydrate to calcium sulfate hemihydrate is large and the industry suggests that drying can be done at higher temperatures for shorter periods of time.
Example 6: application of embodiment 1
According to the types of the fillers indicated in table 5, seven calcium sulfate micro-nano composite products prepared by the method are selected, namely a composite product 1 (0.09 mol of sulfuric acid product is added in example 1), a composite product 2 (0.125 mol of sulfuric acid product is added in example 2), a composite product 3 (product a in example 3), a composite product 4 (product b in example 3), a composite product 5 (product c in example 3), a composite product 6 (product d in example 3), a composite product 7 (ethanol/water system product in example 4) and polypropylene (PP) are extruded and granulated on an internal mixer, then injection molding is carried out on the mixture by an injection molding machine to form more than five standard sample bars for a series of performance tests, and the test results are averaged. Compared with the addition application effect data of nano calcite type calcium carbonate and whisker calcium sulfate, the addition percentage is 10-50 percent respectively.
TABLE 5 Performance evaluation results of PP-filled calcium sulfate micro-nano composite product
According to the comparison and analysis of PP resin filling data, the calcium sulfate/white carbon black compound product synthesized by a sulfuric acid method or an ammonium sulfate method is most obvious in the aspects of improving the strength and the impact toughness, particularly has obvious application effect on improving the toughness and the processing performance of the composite material, and is better in the effect of the stearic acid modified product.
Example 7: application embodiment 2
Similarly, the calcium sulfate micro-nano composite product 2 (0.125 mol of sulfuric acid product is added in the example 2) and the calcium sulfate micro-nano composite product 7 (ethanol/water system product in the example 4) are compounded with cement clinker, then the mixture is cured and formed, the compression mechanical property test is carried out, the test results are averaged, and the preliminary evaluation results are shown in the table 6.
Table 6 preliminary evaluation of the effect of calcium sulfate micro-nano composite product in concrete
The experimental result shows that the compressive strength of the cement paste is obviously increased after two calcium sulfate micro-nano composite products are added, and the effect of the material 2 is better; but the compressive strength of the test block is not obviously improved within 7 days and 28 days, which shows that the material can be used as an early strength agent and a reinforcing and toughening agent in clinker.
Example 8: application implementation 3
Seven calcium sulfate micro-nano composite products prepared by the method are selected, namely a composite product 1 (0.09 mol of sulfuric acid product is added in the example 1), a composite product 2 (0.125 mol of sulfuric acid product is added in the example 2), a composite product 3 (a in the example 3), a composite product 4 (b in the example 3), a composite product 5 (c in the example 3), a composite product 6 (d in the example 3) and a composite product 7 (ethanol/water system product in the example 4). The results of the test of the adhesive force and the water resistance of the aldehyde-free adhesive prepared by adding the components into the styrene-acrylic emulsion are shown in the table 7:
table 7 test results of green adhesive prepared from micro-nano composite material
Experimental results show that the bonding strength of the green adhesive can be greatly improved by adding the calcium sulfate composite product prepared by the method, the bonding strength is not greatly influenced by the addition amount of 5-30%, the bonding strength can be improved by 70-80% when the addition amount of 30%, and the product can completely pass a 63 ℃ water resistance test in the national plywood standard and a 100 ℃ water resistance test in the national plywood standard.
The above description of the embodiments is only intended to facilitate the understanding of the method of the invention and its core idea. It should be noted that, for those skilled in the art, it is possible to make several improvements and modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the scope of the claims of the present invention.
Claims (9)
1. A zero-and/or one-dimensional calcium sulfate-based micro-nanocomposite product, wherein the zero-and/or one-dimensional calcium sulfate-based micro-nanocomposite product comprises: the preparation method of the compound of the calcium sulfate block/sheet/rod/whisker and the nano white carbon black comprises the following steps:
adding a sulfur compound raw material into cement and/or cement clinker and a mixture of the cement and/or cement clinker and lime in a water-containing system at 0-100 ℃, stirring and mixing, and carrying out double decomposition, hydration, neutralization and dehydration condensation reaction for 0.5-10h to synthesize the zero-dimension and/or one-dimension calcium sulfate-based micro-nano composite product;
the sulfur compound raw material is selected from one or more of sulfuric acid, ammonium sulfate, ammonium sulfite, flue gas needing desulfurization, sulfur dioxide, sulfur trioxide or waste sulfuric acid.
2. The calcium sulfate-based micro-nano composite product according to claim 1, wherein the composite product is preferably a one-dimensional calcium sulfate whisker product; the cement is selected from portland cement and aluminosilicate cement; the cement clinker is preferably portland cement clinker.
3. The calcium sulfate-based micro-nano composite product according to claim 1 or 2, wherein the synthesis reaction temperature is 0-100 ℃, and the reaction time is 0.5-10 h; preferably, the one-dimensional product is synthesized for 2-10 hours; preferably, the reaction temperature is 25-60 ℃, and the reaction time is 1-6 h; preferably, the end point of the neutralization reaction is at a pH of 6-8, or the reaction is stopped at any stage where the pH is greater than 7.
4. The calcium sulphate-based micro-nano composite product according to claim 1 or 2, wherein the mass of water in the reaction is at least two times, preferably 2-5 times, that of the solid raw material.
5. The calcium sulfate-based micro-nanocomposite product according to claim 1 or 2, wherein the aqueous system is selected from water, a mixed system of water and an organic solvent, an aqueous solution to which a modifier is added, or a mixed system of water and an organic solvent to which a modifier is added; preferably the organic solvent is selected from C1-C4 alcohol, DMF; the volume ratio of water to organic solvent is 0.2-5.0: 1; the modifier is solid or liquid, the mass ratio of the cement raw material to the modifier is 10-1000: 1; more preferably, the modifier is a small molecule modifier or a high molecule modifier; preferably, the small molecular modifier is stearic acid or stearate, the high molecular modifier is a water-soluble high molecular modifier or a high molecular modifier capable of forming emulsion, and preferably one or more of styrene-acrylic emulsion, sodium lignin, acrylic emulsion, silicone acrylic emulsion, fluorine acrylic emulsion, polyvinyl alcohol, polyethylene glycol, urea-formaldehyde resin, phenolic resin and bio-based sulfonate; preferably, the bio-based sulfonate is lignosulfonate or cellulose sulfonate and further preferably, the method further comprises the steps of filtering, washing and drying the reaction mixture after the reaction is finished.
6. The use of the calcium sulfate-based micro-nano composite product according to any one of claims 1 to 5, characterized in that it is used for cost reduction and quality improvement of synthetic materials, natural materials and composite materials; preferably, the synthetic material, natural material or composite material is plastic, rubber, paint, cement, asphalt, sealant, ink, adhesive or paper; more preferably, the calcium sulfate-based micro-nano composite product is added to the synthetic material, the natural material or the composite material separately, or the calcium sulfate-based micro-nano composite product and other nano materials are added to the synthetic material, the natural material or the composite material in combination.
7. The use according to claim 6, wherein the calcium sulfate-based micro-nano composite product is used for plastics, rubbers to improve tensile strength, peel strength and impact toughness and processability, for adhesives to improve bond strength and water resistance, or for asphalt to improve softening point, penetration and rutting resistance.
8. A reinforcing material comprising the calcium sulfate-based micro-nanocomposite product according to any one of claims 1 to 5, and any one of a synthetic material, a natural material, and a composite material.
9. A method for regenerating ammonia and co-producing a calcium sulfate-based micro-nano composite product, the method comprising the steps of:
in the method for preparing the calcium sulfate-based micro-nano composite product of claim 1, the calcium-based raw material containing cement is subjected to neutralization reaction, ammonium sulfate as an industrial by-product is used as the raw material for neutralization, the pH value is controlled to be 7 or more at the end point of the neutralization reaction, and ammonia is recovered while heating in the neutralization reaction process.
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