A method for preparing a high specific surface area calcium carbonate

Abstract

The application discloses a preparation method of high specific surface area calcium carbonate, which comprises the following steps: (1) calcining limestone to obtain lime, and placing the lime in digestive water added with glucose to obtain a calcium hydroxide suspension, filtering and removing waste residues, and reserving; (2) moving the calcium hydroxide suspension obtained in the step (1) to a bubbling reaction tower, and passing in carbon dioxide mixed gas, adding a mixed solution containing phosphate and scale inhibitor when a gel point is reached, continuing to react until the whole system conductivity is 0.6 us / cm, and then stopping the reaction to obtain a nano calcium carbonate slurry; (3) filtering, washing and drying the nano calcium carbonate slurry in the step (2) to obtain a high specific surface area nano calcium carbonate product. The nano calcium carbonate prepared by the method has the advantages of high specific surface area, good dispersity and the like, the preparation process is simple, industrialized production can be easily realized, and the method has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of calcium carbonate preparation, in particular to a preparation method of high specific surface area calcium carbonate. BACKGROUND

[0002] Calcium carbonate is the most abundant inorganic biomaterial in nature, which exists in different structures: calcite, vanadate and aragonite. Most calcium carbonate sources are mainly composed of calcite, and according to thermodynamics, calcite is the most stable phase among other polymorphic phases. Calcium carbonate has the advantages of simple synthesis, non-toxicity, good biocompatibility, large surface area, low cost and the like, and is widely applied to the fields of construction, bone cement, dental implants, stents and the like in the medical field. In addition, calcium carbonate has a strong demand in paper, plastic, rubber, paint and adhesive as an abrasive, absorbent and filler to improve the rheological properties and mechanical properties of products.

[0003] The fillers in the fields of rubber, ink, silicone sealant and the like are generally carbon black, white carbon black, calcium carbonate, magnesium carbonate, dolomite powder and the like. Compared with other fillers (such as white carbon black), calcium carbonate has lower price and higher filling rate. Meanwhile, the nano calcium carbonate with high specific surface area can also improve the properties of rubber, such as hardness, tensile strength, wear resistance and the like.

[0004] In order to obtain the nano calcium carbonate product with high specific surface area, relevant industry professionals have made a lot of exploration work on the preparation process and method thereof.

[0005] Du Nianjun and Sun Yongfeng synthesized the nano calcium carbonate with high specific surface area. The nano calcium carbonate is analyzed by a BET specific surface area tester and a TEM transmission electron microscope, the primary particle size is 10-20 nm, and the specific surface area reaches 100-120 m 2 / g. The high specific surface area nano calcium carbonate is obtained through surface modification, drying and crushing after adding a chelating agent before carbonization, adding a polyhydric alcohol in the carbonization process and adding a compound agent of an organic acid salt and an inorganic acid ester when the conductivity rapidly decreases.

[0006] Liu Haodi, Zhao Rongfang and Chen Yunfa successfully synthesized the calcium carbonate with high specific surface area by adding humic acid into a calcium hydroxide suspension for carbonization preparation. The specific surface area of the calcium carbonate, the pore distribution and the particle morphology in the reaction process are analyzed by adopting the methods of BET, XRD and SEM, it is found that the humic acid can change the specific surface area of the calcium carbonate product and the microcrystal morphology, with the increase of the humic acid amount, the particle morphology of the calcium carbonate changes from a spherical shape to a rod shape and then to a cubic shape; with the increase of the humic acid amount, the specific surface area of the obtained calcium carbonate obviously increases, and the average pore diameter decreases with the increase of the humic acid amount.

[0007] Chinese patent CN111606344B discloses a method for preparing high specific surface area nano calcium carbonate, comprising the following steps: 1) adding urea to calcium hydroxide suspension and stirring to mix, adjusting pH value with ammonia water to obtain slurry A, heating slurry A to 35-40℃ constant temperature, passing in mixed gas of carbon dioxide and nitrogen, stopping passing in mixed gas when pH value of slurry A is 6.5-7, continuing stirring for 1-2h to obtain slurry B; 2) heating slurry B to 80-90℃ constant temperature under stirring, then adding composite modifier and keeping for 2-5h to obtain nano calcium carbonate suspension, finally filtering and freeze-drying to obtain nano calcium carbonate. This method has complex process flow, is not easy to industrialize and has poor economic benefit.

[0008] Chinese patent CN112811456A discloses a high specific surface area nano calcium carbonate and a preparation method thereof, which comprises the following steps in sequence: (1) passing in calcium hydroxide slurry with a temperature of 20-25℃ into a carbonization reactor, continuously adding nucleating agent, then passing in high-pressure pure carbon dioxide gas, and stirring at high speed to generate calcium carbonate crystal nucleus; (2) controlling the temperature of the carbonization reactor below 35℃, supplementing calcium hydroxide slurry with a temperature of 10-15℃ into the carbonization reactor, continuously adding crystal nucleus growth control agent, passing in pure carbon dioxide gas, and stirring at low speed to prepare high specific surface area nano calcium carbonate slurry. This method uses high-pressure pure carbon dioxide with high cost in industry, has low economic benefit, and produces a large amount of tail gas, which does not meet the green and pollution-free environmental protection concept.

[0009] Chinese patent CN104059390B discloses a modified calcium carbonate with high specific surface area, which is prepared from the following raw materials by weight: calcium carbonate 90-95, methyl methacrylate 4-6, melamine resin 5-7, decanedioic acid propylene glycol polyester 3-4, coconut shell activated carbon 2-3, fly ash 2-3, ammonium bicarbonate 1-1.5, turpentine 2-3, polysorbate 80 1-2, modified titanium dioxide 2.5-3.5. Finally, modified calcium carbonate with high surface area is obtained. This method uses many modifiers, has high cost, complex process and is not easy to popularize.

[0010] Chinese patent CN109453733A discloses a high specific surface area modified calcium carbonate filter material, a preparation method thereof and a composite material. The preparation method of the high specific surface area modified calcium carbonate filter material comprises the following steps: (1) placing calcium carbonate filter material in a low-temperature plasma generator; (2) passing in action gas; (3) starting the low-temperature plasma generator, adjusting discharge voltage, and performing plasma treatment. Finally, the prepared calcium carbonate powder has small size and large specific surface area. The plasma generator used in this method has high cost in industry and very little economic benefit.

[0011] Chinese patent CN115872432A discloses a method for preparing spherical calcium carbonate and improving specific surface area by regulation and modification. The steps are as follows: (1) sodium carbonate and calcium chloride are used as raw materials; (2) CMC is used as crystal shape regulator and modifier, and ultrasonic assistance is adopted, and finally spherical calcium carbonate is prepared. This method adopts ultrasonic, which has high cost in industry and is not suitable for popularization.

[0012] In summary, the existing preparation process for obtaining high specific surface area nano calcium carbonate has the problems of easy agglomeration of calcium carbonate and high production cost. SUMMARY

[0013] The present application provides a preparation method of high specific surface area calcium carbonate, which has the advantages of high specific surface area, good dispersibility, simple preparation process, easy industrial production and good application prospect.

[0014] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0015] A preparation method of high specific surface area calcium carbonate comprises the following steps:

[0016] (1) calcining limestone to obtain lime, and placing the lime in digestion water added with glucose to obtain calcium hydroxide suspension, filtering to remove waste residue, and reserving for use;

[0017] (2) moving the calcium hydroxide suspension obtained in step (1) to a bubbling reaction tower, and introducing carbon dioxide mixed gas, adding a mixed solution containing phosphate and scale inhibitor when the gel point is reached, continuing to react until the conductivity of the whole system is 0.6 us / cm, and then stopping the reaction to obtain nano calcium carbonate slurry;

[0018] (3) filtering, washing and drying the nano calcium carbonate slurry of step (2) to obtain high specific surface area nano calcium carbonate product.

[0019] Preferably, in step (1), the addition amount of glucose is 0.10% to 0.30% of the dry basis content of calcium hydroxide.

[0020] Preferably, in step (1), the calcination temperature is 1300 to 1600℃, and the time is 150 to 300 min.

[0021] Preferably, in step (1), a 140 to 170 mesh screen is used for filtering.

[0022] Preferably, in step (2), the carbon dioxide concentration is 25 to 35%, and the flow rate is 1 to 4 m 3 / h.

[0023] Preferably, in step (2), the phosphate is one or more of sodium dihydrogen phosphate, trisodium phosphate, disodium hydrogen phosphate, and the addition amount is 0.20-0.40% of the dry content of calcium carbonate.

[0024] Preferably, in step (2), the scale inhibitor is an organic phosphoric acid, and the addition amount is 0.30-0.60% of the dry content of calcium carbonate.

[0025] Preferably, the organic phosphoric acid is one or more of ATMP, HEDP, EDTMPS, DTPMPA, PBTCA, and BHMT.

[0026] Preferably, in step (2), the temperature of the suspension is adjusted to 18-23℃ before the carbon dioxide mixed gas is introduced.

[0027] Preferably, in step (3), the drying temperature is 90-150℃, and the time is 10-22h.

[0028] The principle of the preparation method of the present application is as follows:

[0029] 1. Sugar is added to the digested water, and OH is dissociated from the calcium hydroxide solution - and Ca 2+ The dissociated Ca 2+ forms a "calcium-sugar" complex with the added sugar, inhibiting the crystal growth of calcium hydroxide, so that the particle size is overall small. When carbonized, the small particle calcium hydroxide dissolves quickly, and a large number of calcium carbonate intermediates are generated, which is beneficial to the formation of high specific surface area nano calcium carbonate.

[0030] 2. On the premise of the above-prepared small particle calcium hydroxide, a large number of nano calcium carbonate intermediates are formed in the early stage of carbonization. To form high specific surface area nano calcium carbonate, the growth of the intermediates needs to be inhibited. PO4 3- in the phosphate provides coordination electrons with the methylenephosphonic acid group or O=P-O- structural unit in the scale inhibitor, and chelation occurs with Ca 2+ ions in the CaCO3 surface lattice to form a coordination chemical bond, which is firmly adsorbed on the crystal surface. This adsorption preferentially occurs at the active growth points on the crystal surface, inhibiting the growth of the crystal and reducing the electrostatic force between the nano calcium carbonate crystals, achieving a dispersion effect.

[0031] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0032] 1. The nano calcium carbonate prepared by the present application has high specific surface area, good dispersibility, and the like, and the preparation process is simple, easy to realize industrial production, and has good application prospect.

[0033] 2. The phosphate and scale inhibitor used in the present application are widely available and low in cost, and are safe to use in industrial production. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 is a scanning electron microscope detection photo of the calcium carbonate product prepared in Example 1 of the present application;

[0035] Figure 2 is a scanning electron microscope detection photo of the calcium carbonate product prepared in Example 2 of the present application;

[0036] Figure 3 is a scanning electron microscope detection photo of the calcium carbonate product prepared in Example 3 of the present application;

[0037] Figure 4 is a scanning electron microscope detection photo of the calcium carbonate product prepared in Example 4 of the present application;

[0038] Figure 5 is a scanning electron microscope detection photo of the calcium carbonate product prepared in Comparative Example 1 of the present application;

[0039] Figure 6 is a scanning electron microscope detection photo of the calcium carbonate product prepared in Comparative Example 2 of the present application;

[0040] Figure 7 is a scanning electron microscope detection photo of the calcium carbonate product prepared in Comparative Example 3 of the present application;

[0041] Figure 8 is a scanning electron microscope detection photo of the calcium carbonate product prepared in Comparative Example 4 of the present application. DETAILED DESCRIPTION

[0042] The specific embodiments of the present application are described in detail below, but it should be understood that the scope of protection of the present application is not limited by the specific embodiments.

[0043] Example 1

[0044] A method for preparing a high specific surface area nano calcium carbonate, comprising the following steps:

[0045] (1) limestone is placed at 1300°C for calcination for 300 min to obtain lime, and the lime is placed in digestion water with 0.10% glucose based on the dry content of calcium hydroxide to obtain a calcium hydroxide suspension, the calcium hydroxide suspension is removed from the waste residue through a 140 mesh screen, and finally water is added to adjust the solid content of the calcium hydroxide suspension to 5%;

[0046] (2) The calcium hydroxide suspension obtained in step (1) is moved to a bubbling reactor tower, the temperature of the suspension is adjusted to 18℃, then carbon dioxide mixed gas with a concentration of 25% and a flow rate of 2% is introduced, when the gel point is reached, a mixed solution containing 0.20% of trisodium phosphate and 0.30% of ATMP, HEDP compound of calcium carbonate dry base is added, the reaction continues until the conductivity of the whole system is 0.6 us / cm, then the gas introduction is stopped immediately, the reaction is terminated, and finally the nano calcium carbonate slurry is obtained;

[0047] (3) The nano calcium carbonate slurry of step (2) is filtered, washed, and dried at 90℃ for 22h, and the high specific surface area nano calcium carbonate product of the present application is obtained.

[0048] Example 2

[0049] A method for preparing high specific surface area nano calcium carbonate, comprising the following steps:

[0050] (1) Limestone is calcined at 1400℃ for 250min to obtain lime, and the lime is placed in digestion water with 0.30% of glucose added to the calcium hydroxide dry base to obtain a calcium hydroxide suspension. The calcium hydroxide suspension is passed through a 170 mesh screen to remove waste residues, and finally water is added to adjust the solid content of the calcium hydroxide suspension to 6%;

[0051] (2) The calcium hydroxide suspension obtained in step (1) is moved to a bubbling reactor tower, the temperature of the suspension is adjusted to 20℃, then carbon dioxide mixed gas with a concentration of 28% and a flow rate of 2.5% is introduced, when the gel point is reached, a mixed solution containing 0.30% of trisodium phosphate and 0.45% of EDTMPS, DTPMPA, PBTCA compound of calcium carbonate dry base is added, the reaction continues until the conductivity of the whole system is 0.6 us / cm, then the gas introduction is stopped immediately, the reaction is terminated, and finally the nano calcium carbonate slurry is obtained;

[0052] (3) The nano calcium carbonate slurry of step (2) is filtered, washed, and dried at 100℃ for 20h, and the high specific surface area nano calcium carbonate product of the present application is obtained.

[0053] Example 3

[0054] A method for preparing high specific surface area nano calcium carbonate, comprising the following steps:

[0055] (1) Limestone is calcined at 1500℃ for 200min to obtain lime, and the lime is placed in digestion water with 0.20% of glucose added to the calcium hydroxide dry base to obtain a calcium hydroxide suspension. The calcium hydroxide suspension is passed through a 150 mesh screen to remove waste residues, and finally water is added to adjust the solid content of the calcium hydroxide suspension to 8%;

[0056] (2) The calcium hydroxide suspension obtained in step (1) is moved to a bubbling reactor column, the temperature of the suspension is adjusted to 23°C, then carbon dioxide mixed gas with a concentration of 35% and a flow rate of 1% is introduced, when the gel point is reached, a mixed solution containing 0.40% sodium dihydrogen phosphate based on the dry content of calcium carbonate and 0.60% ATMP based on the dry content of calcium carbonate is added, the reaction continues until the conductivity of the whole system is 0.6 us / cm, then the gas introduction is immediately stopped, the reaction is terminated, and finally the nano calcium carbonate slurry is obtained;

[0057] (3) The nano calcium carbonate slurry of step (2) is filtered, washed, and dried at 150°C for 10h, and the high specific surface area nano calcium carbonate product of the present application is obtained.

[0058] Example 4

[0059] A method for preparing a high specific surface area nano calcium carbonate, comprising the following steps:

[0060] (1) Limestone is calcined at 1600°C for 150min to obtain lime, which is placed in digestion water with 0.15% glucose based on the dry content of calcium hydroxide to obtain a calcium hydroxide suspension. The calcium hydroxide suspension is passed through a 140 mesh screen to remove waste residues, and finally water is added to adjust the solid content of the calcium hydroxide suspension to 7%;

[0061] (2) The calcium hydroxide suspension obtained in step (1) is moved to a bubbling reactor column, the temperature of the suspension is adjusted to 19.5°C, then carbon dioxide mixed gas with a concentration of 30% and a flow rate of 3% is introduced, when the gel point is reached, a mixed solution containing 0.25% sodium dihydrogen phosphate based on the dry content of calcium carbonate, 0.375% ATMP and BHMT complex based on the dry content of calcium carbonate is added, the reaction continues until the conductivity of the whole system is 0.6 us / cm, then the gas introduction is immediately stopped, the reaction is terminated, and finally the nano calcium carbonate slurry is obtained;

[0062] (3) The nano calcium carbonate slurry of step (2) is filtered, washed, and dried at 120°C for 12h, and the high specific surface area nano calcium carbonate product of the present application is obtained.

[0063] Comparative Example 1

[0064] A method for preparing a nano calcium carbonate, comprising the following steps:

[0065] (1) Limestone is calcined at 1500°C for 200min to obtain lime, which is placed in digestion water to obtain a calcium hydroxide suspension. The calcium hydroxide suspension is passed through a 150 mesh screen to remove waste residues, and finally water is added to adjust the solid content of the calcium hydroxide suspension to 8%;

[0066] (2) The calcium hydroxide suspension obtained in step (1) is moved to a bubbling reactor column, the temperature of the suspension is adjusted to 23°C, then carbon dioxide mixed gas with a concentration of 35% and a flow rate of 1% is introduced, when the gel point is reached, a mixed solution containing 0.40% sodium dihydrogen phosphate based on dry calcium carbonate and 0.60% ATMP based on dry calcium carbonate is added, the reaction continues until the conductivity of the whole system is 0.6 us / cm, then the gas introduction is immediately stopped, the reaction is terminated, and finally the nano calcium carbonate slurry is obtained;

[0067] (3) The nano calcium carbonate slurry of step (2) is filtered, washed, and dried at 150°C for 10h, and the high specific surface area nano calcium carbonate product of the present application is obtained.

[0068] Comparative Example 2

[0069] (1) Limestone is calcined at 1500°C for 200min to obtain lime, which is placed in digestion water with 0.20% glucose based on the dry calcium hydroxide content to obtain a calcium hydroxide suspension. The calcium hydroxide suspension is passed through a 150 mesh screen to remove waste residues, and finally water is added to adjust the solid content of the calcium hydroxide suspension to 8%;

[0070] (2) The calcium hydroxide suspension obtained in step (1) is moved to a bubbling reactor column, the temperature of the suspension is adjusted to 23°C, then carbon dioxide mixed gas with a concentration of 35% and a flow rate of 1% is introduced, when the gel point is reached, a mixed solution containing 0.40% sodium dihydrogen phosphate based on dry calcium carbonate and 0.60% ATMP based on dry calcium carbonate is added, the reaction continues until the conductivity of the whole system is 0.6 us / cm, then the gas introduction is immediately stopped, the reaction is terminated, and finally the nano calcium carbonate slurry is obtained;

[0071] (3) The nano calcium carbonate slurry of step (2) is filtered, washed, and dried at 150°C for 10h, and the high specific surface area nano calcium carbonate product of the present application is obtained.

[0072] Comparative Example 3

[0073] (1) Limestone is calcined at 1500°C for 200min to obtain lime, which is placed in digestion water with 0.20% glucose based on the dry calcium hydroxide content to obtain a calcium hydroxide suspension. The calcium hydroxide suspension is passed through a 140 mesh screen to remove waste residues, and finally water is added to adjust the solid content of the calcium hydroxide suspension to 8%;

[0074] (2) The calcium hydroxide suspension obtained in step (1) is moved to a bubbling reactor column, the temperature of the suspension is adjusted to 23°C, then carbon dioxide mixed gas with a concentration of 35% and a flow rate of 1% is introduced, when the gel point is reached, a mixed solution containing 0.40% sodium dihydrogen phosphate based on dry calcium carbonate and 0.60% ATMP based on dry calcium carbonate is added, the reaction continues until the conductivity of the whole system is 0.6 us / cm, then the gas introduction is immediately stopped, the reaction is terminated, and finally the nano calcium carbonate slurry is obtained;

[0075] (3) The nano calcium carbonate slurry of step (2) is filtered, washed, and dried at 150°C for 10h to obtain the high specific surface area nano calcium carbonate product of the present application.

[0076] Comparative Example 4

[0077] (1) Limestone is placed for calcination at 1500°C for 200min to obtain lime, which is placed in digestion water to obtain a calcium hydroxide suspension. The calcium hydroxide suspension is passed through a 150 mesh screen to remove waste residue, and finally water is added to adjust the solid content of the calcium hydroxide suspension to 8%;

[0078] (2) The calcium hydroxide suspension obtained in step (1) is moved to a bubble reaction tower, the temperature of the suspension is adjusted to 23°C, then a carbon dioxide mixed gas with a concentration of 35% and a flow rate of 1% is introduced, and the reaction is stopped immediately when the conductivity of the whole system reaches 0.6us / cm. Finally, the nano calcium carbonate slurry is obtained.

[0079] (3) The nano calcium carbonate slurry of step (2) is filtered, washed, and dried at 150°C for 10h to obtain the high specific surface area nano calcium carbonate product of the present application.

[0080] I. Performance test experiment

[0081] 1. The high specific surface nano calcium carbonate prepared in Examples 1-4 and the nano calcium carbonate powder prepared in Comparative Examples 1-4 are detected by scanning electron microscopy, and the detection results are shown in Figures 1 to 8 .

[0082] As can be seen from Figures 1 to 4 , the high specific surface nano calcium carbonate prepared in Examples 1-4 has regular morphology, good dispersibility, small particles, and an average particle size of about 35nm;

[0083] As can be seen from Figures 5 to 8 , the nano calcium carbonate prepared in Comparative Examples 1-4 has serious agglomeration, large particles, and an average particle size of about 76nm.

[0084] 2. The specific surface area, whiteness and pH value of the nano calcium carbonate prepared in Examples 1-4 and Comparative Examples 1-4 are determined according to GB / T 19587-2017 / ISO 9277:2010, GB / T 23774-2009 and GB / T 23769-2009 using a specific surface area tester, a whiteness meter and a pH meter. The test results are shown in Table 1:

[0085] Table 1 Test results

[0086] Sample Specific surface area / m 2 / g]] Whiteness / % pH value / % Example 1 74.76 98.11 8.95 Example 2 75.32 98.24 8.83 Example 3 76.92 98.88 8.56 Example 4 72.54 98.15 8.35 Comparative Example 1 20.46 88.48 8.24 Comparative Example 2 22.21 88.53 8.46 Comparative Example 3 20.78 89.12 8.21 Comparative Example 4 19.45 87.56 8.67

[0087] From Table 1, the specific surface area and whiteness of the nano calcium carbonate obtained from the examples 1-4 are higher than those of the comparative examples 1-4, and the pH value changes little.

[0088] The specific surface area and whiteness of the calcium carbonate product prepared by not adding glucose in the digestive water based on the example 3 are obviously decreased.

[0089] The specific surface area and whiteness of the calcium carbonate product prepared by not adding the mixed solution containing sodium dihydrogen phosphate and ATMP based on the example 3 are greatly decreased.

[0090] The specific surface area and whiteness of the calcium carbonate product prepared by adding sodium dihydrogen phosphate and ATMP based on the comparative example 4 are improved to a certain extent, but there is still a big gap compared with the example 3.

[0091] II. Application Experiment

[0092] The nano calcium carbonate of the above examples 1-4 and comparative examples 1-4 is prepared into rubber according to the raw materials and mass fraction of Table 2, and the performance test is carried out, and the test results are shown in Table 3.

[0093] Table 2 Table of raw materials and mass fraction of rubber

[0094] Raw materials Mass fraction, % Styrene-butadiene rubber 90 Sulfur 1 Stearic acid 0.5 Accelerator CZ 2 Zinc oxide 5 Antioxidant 4010 0.4 Calcium carbonate prepared in Examples 1 to 4 or Comparative Examples 1 to 4 45

[0095] Table 3 Table of application results of examples and comparative examples

[0096]

[0097] From the above application comparison experiment results, the tensile strength, 100% positioning tensile strength, elongation at break and tear strength of the examples 1-4 are all better than those of the comparative examples 1-4.

[0098] The various indexes of the rubber prepared by the calcium carbonate product prepared based on the example 3 are obviously decreased.

[0099] The various indexes of the rubber prepared by the calcium carbonate product prepared based on the example 3 are greatly decreased.

[0100] The various indexes of the rubber prepared by the calcium carbonate product prepared based on the comparative example 4 are improved to a certain extent by adding sodium dihydrogen phosphate and ATMP, but there is still a big gap compared with the example 3.

[0101] The nano calcium carbonate product prepared by the method has high specific surface area, high whiteness, good dispersibility, excellent processing performance, and stronger reinforcing performance and tear resistance after filling rubber.

[0102] The above-described embodiments are only used to describe the preferred modes of the present application, and are not used to limit the scope of the present application, and various modifications and improvements to the technical solutions of the present application made by those skilled in the art without departing from the design spirit of the present application shall fall within the protection scope of the present application.

Claims

1. A method for the preparation of high specific surface area calcium carbonate, characterized in that, The method comprises the following steps: (1) calcining limestone to obtain lime, the calcining temperature is 1300-1600℃, the time is 150-300min; and placing the lime in digestion water added with glucose to obtain calcium hydroxide suspension, removing waste residue by filtration, and reserving for use; the added amount of glucose is 0.10%-0.30% of the dry basis content of calcium hydroxide; (2) moving the calcium hydroxide suspension obtained in step (1) to a bubbling reaction tower, adjusting the temperature of the suspension to 18-23℃, and introducing carbon dioxide mixed gas; when the gel point is reached, a mixed solution containing phosphate and scale inhibitor is added, and the reaction is continued until the conductivity of the whole system is 0.6us / cm, and the reaction is ended, to obtain nano calcium carbonate slurry; the phosphate is one or more of sodium dihydrogen phosphate, trisodium phosphate, and disodium hydrogen phosphate, and the added amount is 0.20-0.40% of the dry basis content of calcium carbonate; the scale inhibitor is organic phosphonic acid, and the added amount is 0.30-0.60% of the dry basis content of calcium carbonate; the organic phosphonic acid is one or more of ATMP, HEDP, EDTMPS, DTPMPA, PBTCA, and BHMT; (3) filtering, washing, and drying the nano calcium carbonate slurry of step (2) to obtain high specific surface area nano calcium carbonate product.

2. The method of claim 1, wherein: In step (1), the filtration uses 140-170 mesh screen.

3. The method of claim 1, wherein: In step (2), the carbon dioxide concentration is 25-35% and the flow rate is 1-4 m 3 / h.

4. The method of claim 1, wherein: In step (3), the drying temperature is 90-150℃, and the time is 10-22h.

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