CN111170667A - Dihydrate gypsum and preparation method thereof - Google Patents
Dihydrate gypsum and preparation method thereof Download PDFInfo
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- CN111170667A CN111170667A CN202010026400.5A CN202010026400A CN111170667A CN 111170667 A CN111170667 A CN 111170667A CN 202010026400 A CN202010026400 A CN 202010026400A CN 111170667 A CN111170667 A CN 111170667A
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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
- C04B11/00—Calcium sulfate cements
- C04B11/26—Calcium sulfate cements strating from chemical gypsum; starting from phosphogypsum or from waste, e.g. purification products of smoke
- C04B11/262—Calcium sulfate cements strating from chemical gypsum; starting from phosphogypsum or from waste, e.g. purification products of smoke waste gypsum other than phosphogypsum
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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
- C04B11/00—Calcium sulfate cements
- C04B11/06—Calcium sulfate cements starting from anhydrite
Abstract
The invention relates to dihydrate gypsum and a preparation method thereof, wherein the dihydrate gypsum comprises the following raw materials: anhydrite, alum, sodium salt and aqueous solution. In the invention, under the condition of adding a small amount of aqueous solution, the dihydrate gypsum with larger particles can be simply and conveniently prepared, and the addition of the aqueous solution hardly has influence on the later application of the product; wherein the hydration rate of the obtained dihydrate gypsum can reach 93.4 percent at most, and the median diameter can reach 21.88 mu m at most.
Description
Technical Field
The invention relates to the field of dihydrate gypsum, and particularly relates to dihydrate gypsum and a preparation method thereof.
Background
anhydrite, namely anhydrous calcium sulfate, has poor gelling property, and is generally converted into dihydrate gypsum for use in industrial production, the anhydrite is converted into dihydrate gypsum when meeting water, which is a spontaneous process, but the generated dihydrate gypsum particles have the shapes of sheets, rods and needles, and the particles also have different sizes, so the use of the dihydrate gypsum is usually limited due to different sizes.
At present, the method for increasing the particle size of calcium sulfate dihydrate particles through intervention measures in the hydration process of anhydrite (anhydrous calcium sulfate) mainly comprises the step of adding large-particle calcium sulfate dihydrate seed crystals to make Ca in saturated liquid2+And
directly growing on the surface of the seed crystal after precipitation; the size of the crystal is controlled by intuitively controlling a series of parameters such as feeding speed, stirring speed, temperature and the like through the dissolution-crystallization principle of the crystal, but the methods have complex processes and severe operating conditions. The exciting agent for II type anhydrous gypsum rapid hydration and the rapid hydration method disclosed by CN110128045A use dihydrate gypsum seed crystals accounting for 20-50% of the mass of anhydrite to obviously increase the particles of dihydrate gypsum, but the added dihydrate gypsum has larger amount, and when the dihydrate gypsum seed crystals are too much, the reason for the increase of dihydrate gypsum particles after hydration cannot be directly judged. CN106395879A discloses a preparation method of large-particle-size calcium sulfate dihydrate in a wet-process phosphoric acid process, which is characterized in that a composite aqueous solution consisting of a sulfonic acid regulator, an organic weak acid and ammonium salt buffer thereof and a water-soluble polymer dispersant is added to improve the size of the calcium sulfate dihydrate in the wet-process phosphoric acid process, although the addition amount of the composite aqueous solution is 0.005-3% of the mass fraction of a phosphate rock raw material, the formula of the composite aqueous solution is complex, various ammonium salt substances are involved, excessive use can cause the increase of nitrogen content, the compound aqueous solution is harmful to human bodies, and the particles of the dihydrate gypsum can be effectively increased only by adding the compound aqueous solution in three steps, so that the process cost is higher.
Disclosure of Invention
In view of the problems in the prior art, the present invention aims to provide dihydrate gypsum and a preparation method thereof, wherein the dihydrate gypsum provided by the present invention has relatively large particles, and the preparation of the relatively large particles of dihydrate gypsum can be realized by adding a small amount of aqueous solution by the method provided by the present invention.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, the present invention provides dihydrate gypsum, wherein the dihydrate gypsum comprises the following raw materials: anhydrite, alum, sodium salt and aqueous solution.
The dihydrate gypsum provided by the invention realizes the preparation of large-particle dihydrate gypsum through reasonable configuration of the aqueous solution and other components and synergistic effect among the raw material components, and meanwhile, a good effect can be achieved only by adding a very small amount of aqueous solution in the preparation process, and the addition of the aqueous solution has little influence on subsequent utilization.
In a preferred embodiment of the present invention, the anhydrite includes industrial by-product gypsum.
Preferably, the specific surface area of the anhydrite is more than or equal to 500m2/kg, for example, may be 500m2/kg、550m2/kg、600m2/kg、650m2/kg、700m2/kg、750m2/kg、800m2/kg、850m2/kg、900m2/kg、950m2Per kg or 1000m2And/kg, etc., but are not limited to the recited values, and other values not recited in the range are equally applicable.
Preferably, the anhydrite is added in an amount of 98 to 103 parts by weight, for example, 98 parts, 98.5 parts, 99 parts, 99.5 parts, 100 parts, 100.5 parts, 101 parts, 101.5 parts, 102 parts, 102.5 parts, 103 parts, etc., but not limited to the enumerated values, and other values not enumerated within this range are also applicable.
As a preferred embodiment of the present invention, the alum comprises calcined alum.
Preferably, the calcined alum is a powder obtained by calcining aluminum potassium sulfate dodecahydrate at 200-500 ℃ for 1-6h and grinding.
In the present invention, the calcination temperature of the aluminum potassium sulfate dodecahydrate may be 200 ℃, 250 ℃, 300 ℃, 350 ℃, 400 ℃, 450 ℃ or 500 ℃ or the like, but is not limited to the recited values, and other values not recited in the range are also applicable.
In the present method, the calcination time of the potassium aluminum sulfate dodecahydrate may be 1 hour, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, or the like, but is not limited to the recited values, and other values not recited in the range are also applicable.
Preferably, the alum is added in an amount of 4 to 6 parts by weight, for example, 4 parts, 4.2 parts, 4.4 parts, 4.6 parts, 4.8 parts, 5 parts, 5.2 parts, 5.4 parts, 5.6 parts, 5.8 parts, or 6 parts, but not limited to the enumerated values, and other values not enumerated within this range are also applicable.
As a preferred embodiment of the present invention, the sodium salt includes sodium sulfate and sodium chloride.
Preferably, the sodium sulfate is added in an amount of 5 to 7 parts by weight, for example, 5 parts, 5.2 parts, 5.4 parts, 5.6 parts, 5.8 parts, 6 parts, 6.2 parts, 6.4 parts, 6.6 parts, 6.8 parts, or 7 parts, but not limited to the enumerated values, and other values not enumerated within this range are also applicable.
Preferably, the sodium chloride is added in an amount of 29 to 31 parts by weight, for example, 29 parts, 29.2 parts, 29.4 parts, 29.6 parts, 29.8 parts, 30 parts, 30.2 parts, 30.4 parts, 30.6 parts, 30.8 parts, or 40 parts, but not limited to the recited values, and other values not recited in this range are also applicable.
In a preferred embodiment of the present invention, the amount of the aqueous solution added is 5 to 7 times the amount of the anhydrite added, and may be, for example, 5 times, 5.2 times, 5.4 times, 5.6 times, 5.8 times, 6 times, 6.2 times, 6.4 times, 6.6 times, 6.8 times, or 7 times, but is not limited to the above-mentioned values, and other values not shown in the above range are also applicable.
As a preferable embodiment of the present invention, the aqueous solution includes 1 or a combination of at least 2 of an ethylenediamine tetramethylene phosphonic acid solution, a hydroxyethylidene diphosphonic acid solution, an aminotrimethylene phosphoric acid solution, a tartaric acid solution, a citric acid solution, a nitrilotriacetic acid solution, an ethylenediamine tetraacetic acid solution, a polyacrylic acid solution, a sodium hexametaphosphate solution, a sodium trimetaphosphate solution, a diethylenetriamine pentamethylphosphonic acid solution, and an N-bis (phosphine hydroxymethyl) glycine solution.
Preferably, the concentration of the aqueous solution is 10-11-10-3mol/L, for example, may be 10-3mol/L、10-3.5mol/L、10-4mol/L、10-4.5mol/L、10-5mol/L、10-5.5mol/L、10-6mol/L、10-6.5mol/L、10-7mol/L、10- 7.5mol/L、10-8mol/L、10-8.5mol/L、10-9mol/L、10-9.5mol/L、10-10mol/L、10-10.5mol/L or 10- 11mol/L, etc., but are not limited to the recited values, and other values not recited in the range are also applicable.
In the invention, when the aqueous solution is an ethylenediamine tetramethylene phosphonic acid solution, the concentration of the aqueous solution is 3.82X 10-7-3.82×10-4mol/L may be, for example, 3.82X 10-7mol/L、3.82×10-6.5mol/L、3.82×10-6mol/L、3.82×10- 5.5mol/L、3.82×10-5mol/L、3.82×10-4.5mol/L or 3.82X 10-4mol/L, etc., but are not limited to the recited values, and other values not recited in the range are also applicable.
In the present invention, when the aqueous solution is a hydroxyethylidene diphosphonic acid solution, the concentration thereof is 8.09X 10-9-8.09×10-4mol/L may be, for example, 8.09X 10-9mol/L、8.09×10-8mol/L、8.09×10-7mol/L、8.09×10-6mol/L、8.09×10-5mol/L or 8.09X 10-4mol/L, etc., but are not limited to the recited values, and other values not recited in the range are also applicable.
In the present invention, when the aqueous solution is an aminotrimethylene phosphoric acid solution, the concentration thereof is 3.35X 10-8-3.35×10-3mol/L may be, for example, 3.35X 10-8mol/L、3.35×10-7mol/L、3.35×10-6mol/L、3.35×10- 5mol/L、3.35×10-4mol/L or 3.35X 10-3mol/L, etc., but are not limited to the recited values, and other values not recited in the range are also applicable.
In the present invention, when the aqueous solution is a tartaric acid solution, the concentration thereof is 1.11X 10-6-1.11×10-3mol/L may be, for example, 1.11X 10-6mol/L、1.11×10-5.5mol/L、1.11×10-5mol/L、1.11×10-4.5mol/L、1.11×10-4mol/L、1.11×10-3.5mol/L or 1.11X 10-3mol/L, etc., but are not limited to the recited values, and other values not recited in the range are also applicable.
In the present invention, when the aqueous solution is a citric acid solution, the concentration thereof is 7.931 × 10-9-7.931×10-4mol/L may be, for example, 7.931X 10-9mol/L、7.931×10-8.5mol/L、7.931×10-8mol/L、7.931×10- 7.5mol/L、7.931×10-7mol/L、7.931×10-6.5mol/L、7.931×10-6mol/L、7.931×10-5.5mol/L、7.931×10-5mol/L、7.931×10-4.5mol/L or 7.931X 10-4mol/L, etc., but are not limited to the recited values, and other values not recited in the range are also applicable.
In the present invention, when the aqueous solution is a nitrilotriacetic acid solution, the concentration thereof is 8.72X 10-7-8.72×10- 4mol/L may be, for example, 8.72X 10-7mol/L、8.72×10-6.5mol/L、8.72×10-6mol/L、8.72×10- 5.5mol/L、8.72×10-5mol/L、8.72×10-4.5mol/L or 8.72X 10-4mol/L, etc., but are not limited to the recited values, and other values not recited in the range are also applicable.
In the present invention, when the aqueous solution is an ethylenediaminetetraacetic acid solution, the concentration thereof is 5.7X 10-7-5.7×10- 4mol/L may be, for example, 5.7X 10-7mol/L、5.7×10-6.5mol/L、5.7×10-6mol/L、5.7×10-5.5mol/L、5.7×10-5mol/L、5.7×10-4.5mol/L or 5.7X 10-4mol/L, etc., but are not limited to the recited values, and other values not recited in the range are also applicable.
In the present invention, when the aqueous solution is a polyacrylic acid solution, the concentration thereof is 5.0X 10-7-5.0×10-4mol/L may be, for example, 5.0X 10-7mol/L、5.0×10-6.5mol/L、5.0×10-6mol/L、5.0×10-5.5mol/L、5.0×10-5mol/L、5.0×10-4.5mol/L or 5.0X 10-4mol/L, etc., but are not limited to the recited values, and other values not recited in the range are also applicable.
In the present invention, when the aqueous solution is a sodium hexametaphosphate solution, the concentration thereof is 2.72X 10-7-2.72×10- 4mol/L may be, for example, 2.72X 10-7mol/L、2.72×10-6mol/L、2.72×10-5mol/L or 2.72X 10-4mol/L, etc., but are not limited to the recited values, and other values not recited in the range are also applicable.
In the invention, when the aqueous solution is sodium trimetaphosphate solution, the concentration of the aqueous solution is 5.4 multiplied by 10-11-5.4×10-4mol/L may be, for example, 5.4X 10-11mol/L、5.4×10-10mol/L、5.4×10-9mol/L、5.4×10-8mol/L、5.4×10-7mol/L、5.4×10-6mol/L、5.4×10-5mol/L or 5.4X 10-4mol/L, etc., but are not limited to the recited values, and other values not recited in the range are also applicable.
In the invention, when the aqueous solution is a diethylenetriamine pentamethylphosphonic acid solution, the concentration of the aqueous solution is 2.9 multiplied by 10-7-2.9×10-4mol/L may be, for example, 2.9X 10-7mol/L、2.9×10-6mol/L、2.9×10-5mol/L or 2.9X 10- 4mol/L, etc., but are not limited to the recited values, and other values not recited in the range are also applicable.
In the present invention, when the aqueous solution is an N-bis (phosphine hydroxymethyl) glycine solution, the concentration thereof is 6.33X 10-9-6.33×10-4mol/L may be, for example, 6.33X 10-9mol/L、6.33×10-8mol/L、6.33×10-7mol/L、6.33×10-6mol/L、6.33×10-5mol/L or 6.33X 10-4mol/L, etc., but are not limited to the recited values, and other values not recited in the range are also applicable.
In a second aspect, the present invention provides a method for preparing dihydrate gypsum according to the first aspect, the method comprising: mixing and stirring anhydrite, alum, sodium salt and aqueous solution to obtain dihydrate gypsum.
In a preferred embodiment of the present invention, the stirring temperature is 0 to 42 ℃ and may be, for example, 0 ℃, 2 ℃, 4 ℃, 6 ℃, 8 ℃, 10 ℃, 12 ℃, 14 ℃, 16 ℃, 18 ℃, 20 ℃, 22 ℃, 24 ℃, 26 ℃, 28 ℃, 30 ℃, 32 ℃, 34 ℃, 36 ℃, 38 ℃, 40 ℃ or 42 ℃, but is not limited to the recited values, and other values not recited in the range are also applicable.
Preferably, the rotational speed of the stirring is 100 to 250r/min, for example, 100r/min, 110r/min, 120r/min, 130r/min, 140r/min, 150r/min, 160r/min, 170r/min, 180r/min, 190r/min, 200r/min, 210r/min, 220r/min, 230r/min, 240r/min or 250r/min, etc., but is not limited to the values listed, and other values not listed in this range are equally applicable.
In a preferred embodiment of the present invention, the stirring time is not less than 15 hours, for example, 15 hours, 17 hours, 19 hours, 20 hours, 22 hours, 24 hours, 26 hours, 28 hours, 30 hours, 32 hours, 34 hours, 36 hours, 38 hours, 40 hours, 42 hours, 44 hours, 46 hours, or 48 hours, but is not limited to the above-mentioned values, and other values not listed in the above range are also applicable.
As a preferred technical solution of the present invention, the preparation method comprises: mixing anhydrite, alum, sodium salt and water solution, and stirring at 0-42 ℃ and the rotating speed of 100-250r/min for at least 15h to obtain dihydrate gypsum; wherein the anhydrite comprises industrial by-product gypsum; the specific surface area of the anhydrite is less than or equal to 500m2Per kg; the adding amount of the anhydrite is 98-103 parts by weight; the alum comprises calcined alum; the calcined alum is powder obtained by calcining aluminum potassium sulfate dodecahydrate at 200-500 ℃ for 1-6h and grinding; the adding amount of the alum is 4-6 parts by weight; the sodium salts include sodium sulfate and sodium chloride; the addition amount of the sodium sulfate is 5-7 parts by weight; the addition amount of the sodium chloride is 29-31 parts by weight; the aqueous solution comprises an ethylene diamine tetra methylene phosphonic acid solution, a hydroxy ethylidene diphosphonic acid solution, an amino trimethylene phosphoric acid solution, a tartaric acid solution, a citric acid solution,1 or a combination of at least 2 of a nitrilotriacetic acid solution, an ethylenediamine tetraacetic acid solution, a polyacrylic acid solution, a sodium hexametaphosphate solution, a sodium trimetaphosphate solution, a diethylenetriamine pentamethylphosphonic acid solution and an N-bis (phosphine hydroxymethyl) glycine solution; the concentration of the aqueous solution is 10-11-10-3mol/L; the addition amount of the aqueous solution is 5-7 times of that of the anhydrite.
Compared with the prior art, the invention has the following beneficial effects:
the dihydrate gypsum provided by the invention can be simply and conveniently prepared to obtain dihydrate gypsum with larger particles under the condition of adding a small amount of aqueous solution, and the addition of the aqueous solution hardly has influence on the later application of the product; wherein the hydration rate of the obtained dihydrate gypsum can reach 93.4 percent at most, and the median diameter can reach 21.88 mu m at most.
Drawings
FIG. 1 is a micrograph of dihydrate gypsum obtained in example 6.
The present invention is described in further detail below. The following examples are merely illustrative of the present invention and do not represent or limit the scope of the claims, which are defined by the claims.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings.
To better illustrate the invention and to facilitate the understanding of the technical solutions thereof, typical but non-limiting examples of the invention are as follows:
example 1
This example provides a method of preparing dihydrate gypsum, the method comprising the steps of:
firstly, 7.931 x 10 are respectively configured-9mol/L、7.931×10-5mol/L and 7.931X 10-4Taking 100 parts of citric acid solution with the specific surface area of 550m in mol/L2Adding 6 times of citric acid solution of fluorgypsum/kg, calcined alum 5, sodium sulfate 5.8, sodium chloride 29.5 and anhydrite 6 times by weight into a reactor, and stirring at 25 deg.C and 200r/minStirring for 24h to obtain dihydrate gypsum;
wherein, after reaching the set hydration end point, the hydration product is stopped hydrating by absolute ethyl alcohol, filtering by rapid filter paper, washing for 3 times by absolute ethyl alcohol, drying in a vacuum drying oven at 50 ℃ to constant weight, measuring the content of crystal water, calculating the corresponding hydration rates of the dihydrate gypsum obtained by citric acid solutions with different concentrations to respectively be 88.3 percent, 85.8 percent and 83.0 percent, and the median diameters are respectively 15.55 mu m, 21.88 mu m and 13.4 mu m.
Example 2
This example provides a method of preparing dihydrate gypsum, the method comprising the steps of:
first, 5.4 × 10 chips are arranged-8mol/L、5.4×10-7mol/L and 5.4X 10-4Taking 101 parts of sodium trimetaphosphate solution with the specific surface of 600m in mol/L2Putting fluorgypsum of per kg, calcined alum of 4.8 parts, sodium sulfate of 5.9 parts, sodium chloride of 30 parts and sodium trimetaphosphate solution of 6 times of the weight of anhydrite into a reactor, and stirring for 24 hours at the temperature of 25 ℃ and at the speed of 190r/min to obtain dihydrate gypsum;
wherein, after reaching the set hydration end point, the hydration product is stopped hydrating by absolute ethyl alcohol, filtering by rapid filter paper, washing 3 times by absolute ethyl alcohol, drying in a vacuum drying oven at 50 ℃ to constant weight, measuring the content of crystal water, calculating the hydration rates of dihydrate gypsum obtained by corresponding sodium trimetaphosphate solutions with different concentrations to 91.3 percent, 90 percent and 90 percent respectively, and the median diameters of the dihydrate gypsum are respectively 13.42 mu m, 18.69 mu m and 17.49 mu m.
Example 3
This example provides a method of preparing dihydrate gypsum, the method comprising the steps of:
first, respectively configure 8.09 × 10-9mol/L、8.09×10-7mol/L and 8.09X 10-5Taking 103 parts of hydroxyethylidene diphosphonic acid solution with the mol/L specific surface area of 650m2Putting fluorgypsum, 5.5 parts of calcined alum, 6 parts of sodium sulfate, 30.2 parts of sodium chloride and 6.6 times of hydroxyethylidene diphosphonic acid solution in parts by weight of anhydrite into a reactor, and stirring for 24 hours at 30 ℃ and 200r/min to obtain dihydrate gypsum;
wherein, after reaching the set hydration end point, the hydration product is stopped hydrating by absolute ethyl alcohol, filtering by rapid filter paper, washing 3 times by absolute ethyl alcohol, drying to constant weight in a vacuum drying oven at 50 ℃, measuring the content of crystal water, calculating hydroxy ethylidene diphosphonic acid solutions with different concentrations to obtain corresponding hydration rates of dihydrate gypsum of 87.6 percent, 91.7 percent and 91.2 percent respectively, and the median diameters of 17.56 mu m, 15.69 mu m and 13.02 mu m respectively.
Example 4
First, 3.35 × 10 are respectively configured-8mol/L、3.35×10-5mol/L and 3.35X 10-3Taking 99 parts of aminotrimethylene phosphoric acid solution with the specific surface area of 700m2Putting fluorgypsum of per kg, 5 parts of calcined alum, 6 parts of sodium sulfate, 30 parts of sodium chloride and 6 times of aminotrimethylene phosphoric acid solution of anhydrite by weight into a reactor, and stirring for 24 hours at 35 ℃ and 210r/min to obtain dihydrate gypsum;
wherein, after reaching the set hydration end point, the hydration product is stopped hydrating by absolute ethyl alcohol, filtering by rapid filter paper, washing 3 times by absolute ethyl alcohol, drying to constant weight in a vacuum drying oven at 50 ℃, measuring the content of crystal water, calculating aminotrimethylene phosphoric acid solution with different concentrations to obtain the hydration rates of the corresponding dihydrate gypsum of 89.5 percent, 89.5 percent and 89.4 percent respectively, and the median diameter is 17.27 mu m, 16.73 mu m and 13.05 mu m respectively.
Example 5
First, the molar concentrations were set to 6.33X 10-9mol/L、6.33×10-7mol/L and 6.33X 10-4Taking 103 parts of N-bis (phosphine hydroxymethyl) glycine solution with the specific surface area of 750m by mol/L2Putting fluorgypsum of per kg, calcined alum of 4.9 parts, sodium sulfate of 5.3 parts, sodium chloride of 29 parts and N-bis (phosphine hydroxymethyl) glycine solution of 6.5 times of the weight part of anhydrite into a reactor, and stirring for 24 hours at the temperature of 15 ℃ and the speed of 160r/min to obtain dihydrate gypsum;
wherein, after reaching the set hydration end point, the hydration product is stopped hydrating by absolute ethyl alcohol, filtering by rapid filter paper, washing for 3 times by absolute ethyl alcohol, drying to constant weight in a vacuum drying oven at 50 ℃, measuring the content of crystal water, calculating N-bis (phosphine hydroxymethyl) glycine solutions with different concentrations to obtain the corresponding hydration rates of dihydrate gypsum of 85.5 percent, 92.8 percent and 84.8 percent respectively, and the median diameters of 16.25 mu m, 15.97 mu m and 12.76 mu m respectively.
Example 6
First, 5.7 × 10 parts are respectively arranged-7mol/L、5.7×10-6mol/L and 5.7X 10-4Taking 102 parts of ethylenediamine tetraacetic acid solution with the specific surface area of 800m2Putting fluorgypsum of per kg, calcined alum of 4.3 parts, sodium sulfate of 6.3 parts, sodium chloride of 30.6 parts and ethylenediamine tetraacetic acid solution of 6 times of the weight of anhydrite into a reactor, and stirring for 24 hours at 10 ℃ and 180r/min to obtain dihydrate gypsum;
wherein, after reaching the set hydration end point, the hydration product is stopped hydrating by absolute ethyl alcohol, filtering by rapid filter paper, washing 3 times by absolute ethyl alcohol, drying to constant weight in a vacuum drying oven at 50 ℃, measuring the content of crystal water, calculating the edetic acid solution with different concentrations to obtain the corresponding hydration rates of dihydrate gypsum of 83.3 percent, 86 percent and 84.8 percent respectively, the median diameter is 15.32 mu m, 15.58 mu m and 13.2 mu m respectively, and the crystal is mainly diamond-shaped and detailed as shown in figure 1.
Example 7
First, 3.82 × 10 are respectively configured-7mol/L、3.82×10-6mol/L and 3.82X 10-4Taking 101 parts of ethylenediamine tetramethylene phosphonic acid solution with the specific surface area of 850m in mol/L2Putting fluorgypsum of per kg, 5 parts of calcined alum, 6.3 parts of sodium sulfate, 29.5 parts of sodium chloride and 6 times of ethylene diamine tetra methylene phosphonic acid solution of anhydrite by weight into a reactor, and stirring for 24 hours at 31 ℃ and 200r/min to obtain dihydrate gypsum;
wherein, after reaching the set hydration end point, the hydration product is stopped hydrating by absolute ethyl alcohol, filtering by rapid filter paper, washing 3 times by absolute ethyl alcohol, drying to constant weight in a vacuum drying oven at 50 ℃, measuring the content of crystal water, calculating the ethylene diamine tetraacetic acid solution with different concentrations to obtain the hydration rates of the corresponding dihydrate gypsum of 90.7 percent, 88.1 percent and 85.9 percent respectively, and the median diameter is 13.41 mu m, 15.13 mu m and 13.93 mu m respectively.
Example 8
First, 5.0 × 10 parts are respectively arranged-7mol/L、5.0×10-6mol/L and 5.0X 10-4molTaking 100 parts of polyacrylic acid solution with specific surface area of 900m2Putting fluorgypsum of per kg, calcined alum of 4 parts, sodium sulfate of 5.6 parts, sodium chloride of 30 parts and polyacrylic acid solution of which the weight part is 5.9 times that of anhydrite into a reactor, and stirring for 24 hours at 35 ℃ and 240r/min to obtain dihydrate gypsum;
wherein, after reaching the set hydration end point, the hydration product is stopped hydrating by absolute ethyl alcohol, filtering by rapid filter paper, washing for 3 times by absolute ethyl alcohol, drying to constant weight in a vacuum drying oven at 50 ℃, measuring the content of crystal water, calculating polyacrylic acid solutions with different concentrations to obtain the hydration rates of the corresponding dihydrate gypsum of 87.3 percent, 87.8 percent and 87.9 percent respectively, and the median diameter is 14.76 mu m, 15.12 mu m and 13.55 mu m.
Example 9
First, 1.11 × 10 is respectively disposed-6mol/L、1.11×10-5mol/L and 1.11X 10-3Taking 103 parts of tartaric acid solution with the specific surface area of 500m by mol/L2Putting fluorgypsum of per kg, 5 parts of calcined alum, 5.6 parts of sodium sulfate, 31 parts of sodium chloride and tartaric acid solution of which the weight part is 6.3 times that of anhydrite into a reactor, and stirring for 24 hours at 40 ℃ and 250r/min to obtain dihydrate gypsum;
wherein, after reaching the set hydration end point, the hydration product is stopped hydrating by absolute ethyl alcohol, filtering by rapid filter paper, washing 3 times by absolute ethyl alcohol, drying to constant weight in a vacuum drying oven at 50 ℃, measuring the content of crystal water, calculating tartaric acid solutions with different concentrations to obtain the hydration rates of the corresponding dihydrate gypsum of 92.3 percent, 87.8 percent and 93.4 percent respectively, and the median diameters of 14.81 mu m, 14.74 mu m and 13.25 mu m respectively.
Example 10
First, 8.72 × 10 are respectively configured-7mol/L、8.72×10-6mol/L and 8.72X 10-4Taking 100 parts of nitrilotriacetic acid solution with the specific surface area of 1000m in mol/L2Putting fluorgypsum of per kg, 5 parts of calcined alum, 6.2 parts of sodium sulfate, 29 parts of sodium chloride and 6.5 times of nitrilotriacetic acid solution of anhydrite by weight into a reactor, and stirring for 24 hours at 30 ℃ and 160r/min to obtain dihydrate gypsum;
wherein, after reaching the set hydration end point, the hydration product is stopped hydrating by absolute ethyl alcohol, filtering by rapid filter paper, washing 3 times by absolute ethyl alcohol, drying to constant weight in a vacuum drying oven at 50 ℃, measuring the content of crystal water, calculating nitrilotriacetic acid solutions with different concentrations to obtain the hydration rates of the corresponding dihydrate gypsum of 86.5 percent, 89.5 percent and 91.7 percent respectively, and the median diameter is 14.69 mu m, 13.5 mu m and 13.61 mu m respectively.
Example 11
First, 2.72 × 10 are respectively configured-7mol/L、2.72×10-6mol/L and 2.72X 10-4Taking 101 parts of sodium hexametaphosphate solution with the specific surface area of 650m in mol/L2Putting fluorgypsum of per kg, calcined alum of 5.5 parts, sodium sulfate of 6.8 parts, sodium chloride of 29.4 parts and sodium hexametaphosphate solution of 6 times of the weight of anhydrite into a reactor, and stirring for 24 hours at the temperature of 25 ℃ and the speed of 170r/min to obtain dihydrate gypsum;
wherein, after reaching the set hydration end point, the hydration product is stopped hydrating by absolute ethyl alcohol, filtering by rapid filter paper, washing 3 times by absolute ethyl alcohol, drying to constant weight in a vacuum drying oven at 50 ℃, measuring the content of crystal water, calculating sodium hexametaphosphate solutions with different concentrations to obtain the hydration rates of the corresponding dihydrate gypsum of 91.2 percent, 93.4 percent and 90 percent respectively, and the median diameters of 13.91 mu m, 15.54 mu m and 13.62 mu m respectively.
Example 12
First, 2.9 × 10 are respectively configured-7mol/L、2.9×10-6mol/L and 2.9X 10-4Taking 100 parts of diethylenetriamine pentamethylphosphonic acid solution with the specific surface area of 550m by mol/L2Putting fluorine gypsum/kg, 6 parts of calcined alum, 7 parts of sodium sulfate, 30 parts of sodium chloride and 6 times of diethylenetriamine pentamethylphosphonic acid solution in parts by weight of anhydrite into a reactor, and stirring for 24 hours at 25 ℃ and 200r/min to obtain dihydrate gypsum;
wherein, after reaching the set hydration end point, the hydration product is stopped hydrating by absolute ethyl alcohol, filtering by rapid filter paper, washing 3 times by absolute ethyl alcohol, drying to constant weight in a vacuum drying oven at 50 ℃, measuring the content of crystal water, calculating the hydration rate of the corresponding dihydrate gypsum obtained by the solution of diethylenetriamine pentamethylphosphonic acid to be 90.1 percent, 92.2 percent and 12.79 percent respectively, and the median diameter is 12.79 mu m, 13.1 mu m and 12.85 mu m.
Comparative example 1
The only difference from example 1 is that no aqueous solution was added and the calculated hydration rate of the corresponding dihydrate gypsum was 87.6% and the median diameter was 12.63 μm.
Comparative example 2
The only difference from example 7 is that no aqueous solution was added and the calculated hydration rate of the corresponding dihydrate gypsum was 86.9% and the median diameter was 11.96. mu.m.
Comparative example 3
The only difference from example 12 is that no aqueous solution was added and the calculated hydration rate of the corresponding dihydrate gypsum was 88% and the median diameter was 11.85 μm.
Comparative example 4
The only difference from example 1 is that the concentration in the citric acid solution is 7.931X 10-5Under the condition of mol/L, the used alum is the alum which is not calcined, and the hydration rate of the corresponding dihydrate gypsum is calculated to be 52.3 percent, and the median diameter is 10.08 mu m.
Comparative example 5
The only difference from example 1 is that the concentration in the citric acid solution is 7.931X 10-5Under the condition of mol/L, sodium salt is not added, and the hydration rate of the corresponding dihydrate gypsum is calculated to be 72.6 percent, and the median diameter is 12.75 mu m.
In examples 1 to 12 and comparative examples 1 to 3 and 5 above, the calcined alum was a powder obtained by calcining aluminum potassium sulfate dodecahydrate at 450 ℃ for 1 hour and grinding.
Combining the results of the above examples and comparative examples, it can be seen that the dihydrate gypsum with larger particles can be simply prepared by the method of the present invention under the condition of adding a small amount of aqueous solution, wherein the hydration rate of the dihydrate gypsum can reach up to 93.4%, and the median diameter can reach up to 21.88 μm.
The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (10)
1. The dihydrate gypsum is characterized in that the dihydrate gypsum comprises the following raw materials: anhydrite, alum, sodium salt and aqueous solution.
2. The dihydrate gypsum of claim 1, wherein said anhydrite comprises industrial by-product gypsum;
preferably, the specific surface area of the anhydrite is more than or equal to 500m2/kg；
Preferably, the anhydrite is added in an amount of 98 to 103 parts by weight.
3. The dihydrate gypsum of claim 1 or 2, wherein the alum comprises calcined alum;
preferably, the calcined alum is powder obtained by calcining aluminum potassium sulfate dodecahydrate at 200-500 ℃ for 1-6h and grinding;
preferably, the alum is added in an amount of 4-6 parts by weight.
4. The dihydrate gypsum of any one of claims 1-3, wherein the sodium salt comprises sodium sulfate and sodium chloride;
preferably, the addition amount of the sodium sulfate in parts by weight is 5-7 parts;
preferably, the sodium chloride is added in an amount of 29 to 31 parts by weight.
5. The dihydrate gypsum of any one of claims 1 to 4, wherein the amount of the aqueous solution added is 5 to 7 times the amount of the anhydrite added.
6. The dihydrate gypsum of any one of claims 1 to 5, wherein the aqueous solution comprises 1 or a combination of at least 2 of an ethylenediamine tetramethylene phosphonic acid solution, a hydroxyethylidene diphosphonic acid solution, an aminotrimethylene phosphoric acid solution, a tartaric acid solution, a citric acid solution, a nitrilotriacetic acid solution, an ethylenediamine tetraacetic acid solution, a polyacrylic acid solution, a sodium hexametaphosphate solution, a sodium trimetaphosphate solution, a diethylenetriamine pentamethylphosphonic acid solution, and an N-bis (phosphinomethyl) glycine solution;
preferably, the concentration of the aqueous solution is 10-11-10-3mol/L。
7. The method of producing dihydrate gypsum according to any one of claims 1 to 6, characterized by comprising: mixing and stirring anhydrite, alum, sodium salt and aqueous solution to obtain dihydrate gypsum.
8. The method of any one of claims 1 to 7, wherein the temperature of the stirring is 0 to 42 ℃;
preferably, the rotation speed of the stirring is 100-250 r/min.
9. The process according to any one of claims 1 to 8, wherein the stirring time is not less than 15 hours.
10. The method of any one of claims 1-9, comprising: mixing anhydrite, alum, sodium salt and water solution, and stirring at 0-42 ℃ and the rotating speed of 100-250r/min for at least 15h to obtain dihydrate gypsum; wherein the anhydrite comprises industrial by-product gypsum; the specific surface area of the anhydrite is more than or equal to 500m2Per kg; the adding amount of the anhydrite is 98-103 parts by weight; the alum comprises calcined alum; the calcined alum is aluminum potassium sulfate dodecahydrate calcined at 200-500 deg.CBurning for 1-6h and grinding the obtained powder; the adding amount of the alum is 4-6 parts by weight; the sodium salts include sodium sulfate and sodium chloride; the addition amount of the sodium sulfate is 5-7 parts by weight; the addition amount of the sodium chloride is 29-31 parts by weight; the aqueous solution comprises 1 or the combination of at least 2 of ethylenediamine tetra-methylene phosphonic acid solution, hydroxyethylidene diphosphonic acid solution, aminotrimethylene phosphoric acid solution, tartaric acid solution, citric acid solution, nitrilotriacetic acid solution, ethylenediamine tetraacetic acid solution, polyacrylic acid solution, sodium hexametaphosphate solution, sodium trimetaphosphate solution, diethylenetriamine penta-methyl phosphonic acid solution and N-bis (phosphine hydroxymethyl) glycine solution; the concentration of the aqueous solution is 10-11-10-3mol/L; the addition amount of the aqueous solution is 5-7 times of that of the anhydrite.
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