CN112209857A - Preparation method of dicyandiamide - Google Patents
Preparation method of dicyandiamide Download PDFInfo
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- CN112209857A CN112209857A CN202011186599.4A CN202011186599A CN112209857A CN 112209857 A CN112209857 A CN 112209857A CN 202011186599 A CN202011186599 A CN 202011186599A CN 112209857 A CN112209857 A CN 112209857A
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- dicyandiamide
- cyanamide
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- QGBSISYHAICWAH-UHFFFAOYSA-N dicyandiamide Chemical compound NC(N)=NC#N QGBSISYHAICWAH-UHFFFAOYSA-N 0.000 title claims abstract description 114
- 238000002360 preparation method Methods 0.000 title abstract description 8
- 239000007864 aqueous solution Substances 0.000 claims abstract description 123
- XZMCDFZZKTWFGF-UHFFFAOYSA-N Cyanamide Chemical compound NC#N XZMCDFZZKTWFGF-UHFFFAOYSA-N 0.000 claims abstract description 78
- 238000001914 filtration Methods 0.000 claims abstract description 78
- 239000002245 particle Substances 0.000 claims abstract description 67
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 claims abstract description 46
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 claims abstract description 36
- 239000013078 crystal Substances 0.000 claims abstract description 33
- 229910000019 calcium carbonate Inorganic materials 0.000 claims abstract description 23
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims abstract description 23
- MYFXBBAEXORJNB-UHFFFAOYSA-N calcium cyanamide Chemical compound [Ca+2].[N-]=C=[N-] MYFXBBAEXORJNB-UHFFFAOYSA-N 0.000 claims abstract description 21
- 238000001816 cooling Methods 0.000 claims abstract description 21
- 238000001035 drying Methods 0.000 claims abstract description 21
- 238000006460 hydrolysis reaction Methods 0.000 claims abstract description 21
- 238000006243 chemical reaction Methods 0.000 claims abstract description 19
- 239000001569 carbon dioxide Substances 0.000 claims abstract description 18
- 229910002092 carbon dioxide Inorganic materials 0.000 claims abstract description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 18
- 238000010438 heat treatment Methods 0.000 claims abstract description 17
- 230000000379 polymerizing effect Effects 0.000 claims abstract description 17
- 238000002156 mixing Methods 0.000 claims abstract description 15
- 238000000034 method Methods 0.000 claims abstract description 10
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 15
- 239000004744 fabric Substances 0.000 claims description 15
- 239000000243 solution Substances 0.000 claims description 10
- MVXMNHYVCLMLDD-UHFFFAOYSA-N 4-methoxynaphthalene-1-carbaldehyde Chemical compound C1=CC=C2C(OC)=CC=C(C=O)C2=C1 MVXMNHYVCLMLDD-UHFFFAOYSA-N 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 6
- 230000007062 hydrolysis Effects 0.000 claims description 4
- 239000007789 gas Substances 0.000 claims description 2
- 230000003301 hydrolyzing effect Effects 0.000 claims description 2
- 238000005086 pumping Methods 0.000 claims description 2
- 238000006116 polymerization reaction Methods 0.000 claims 1
- 239000000920 calcium hydroxide Substances 0.000 abstract description 6
- 229910001861 calcium hydroxide Inorganic materials 0.000 abstract description 6
- BRPQOXSCLDDYGP-UHFFFAOYSA-N calcium oxide Chemical compound [O-2].[Ca+2] BRPQOXSCLDDYGP-UHFFFAOYSA-N 0.000 abstract description 5
- 239000000292 calcium oxide Substances 0.000 abstract description 5
- ODINCKMPIJJUCX-UHFFFAOYSA-N calcium oxide Inorganic materials [Ca]=O ODINCKMPIJJUCX-UHFFFAOYSA-N 0.000 abstract description 5
- 239000012535 impurity Substances 0.000 abstract description 5
- 239000000047 product Substances 0.000 description 4
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 3
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000011575 calcium Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 238000004100 electronic packaging Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000005022 packaging material Substances 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 238000003786 synthesis reaction Methods 0.000 description 1
- 238000003828 vacuum filtration Methods 0.000 description 1
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C277/00—Preparation of guanidine or its derivatives, i.e. compounds containing the group, the singly-bound nitrogen atoms not being part of nitro or nitroso groups
- C07C277/08—Preparation of guanidine or its derivatives, i.e. compounds containing the group, the singly-bound nitrogen atoms not being part of nitro or nitroso groups of substituted guanidines
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01C—AMMONIA; CYANOGEN; COMPOUNDS THEREOF
- C01C3/00—Cyanogen; Compounds thereof
- C01C3/16—Cyanamide; Salts thereof
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The application provides a dicyandiamide preparation method, which comprises the steps of mixing lime nitrogen and water for hydrolysis reaction, and introducing carbon dioxide for decalcification reaction to obtain calcium carbonate and a cyandiamide aqueous solution; filtering the cyanamide aqueous solution, and filtering out particles to obtain pure cyanamide aqueous solution; heating and polymerizing the pure cyanamide aqueous solution to obtain a dicyandiamide aqueous solution; and filtering, cooling, filtering and drying the dicyandiamide aqueous solution to obtain dicyandiamide crystals. By adopting the method, impurities such as calcium oxide, calcium hydroxide, calcium carbonate and the like in the dicyandiamide are removed, and the quality of the dicyandiamide product is improved.
Description
Technical Field
The application relates to the technical field of industrial dicyandiamide synthesis, in particular to a preparation method of dicyandiamide.
Background
Dicyandiamide (abbreviated as DICY or DCD) of the formula (NH)2CN)2Dicyandiamide, is a white prismatic crystalline powder soluble in water, alcohol, ethylene glycolAnd dimethylformamide, which is practically insoluble in ether and benzene, is not flammable and stable when dried. The electronic grade dicyandiamide is mainly used in the high-end electronic industry, can be used as an epoxy resin curing agent, an electronic packaging material and the production of an FR-4 copper-clad plate, can also be used as a high-grade coating with higher requirement on the purity of dicyandiamide, an intermediate raw material for chemical pharmacy and the like, and has an increased market demand year by year along with the development of high and new electronic technologies and medicines.
The traditional dicyandiamide preparation method is to hydrolyze calcium cyanamide to obtain calcium cyanamide hydrogen suspension, remove calcium hydroxide filter residue by vacuum filtration, and introduce carbon dioxide into the filtrate to precipitate calcium in the form of calcium carbonate to obtain cyanamide liquid. Polymerizing under alkaline condition, filtering, cooling, crystallizing, separating and drying to obtain dicyandiamide, i.e. dicyandiamide.
The original production process technology of the electronic grade dicyandiamide is to dissolve, filter and crystallize the industrial grade dicyandiamide, and has long process route, large equipment investment and high production cost. The obtained dicyandiamide product also contains impurities such as calcium oxide, calcium hydroxide, calcium carbonate and the like, which influence the quality of the dicyandiamide product.
Disclosure of Invention
The application provides a preparation method of dicyandiamide, which uses calcium oxide, calcium hydroxide, calcium carbonate and other impurities contained in dicyandiamide in the prior art.
The application provides a preparation method of dicyandiamide, which comprises the following steps:
s1: mixing lime nitrogen and water for hydrolysis reaction, and introducing carbon dioxide for decalcification reaction to obtain calcium carbonate and cyanamide aqueous solution;
s2: filtering the cyanamide aqueous solution, and filtering out particles to obtain pure cyanamide aqueous solution;
s3: heating and polymerizing the pure cyanamide aqueous solution to obtain a dicyandiamide aqueous solution;
s4: and filtering, cooling, filtering and drying the dicyandiamide aqueous solution to obtain dicyandiamide crystals.
Optionally, mixing lime nitrogen and water to perform hydrolysis reaction, and introducing carbon dioxide to perform decalcification reaction to obtain an aqueous solution of calcium carbonate and cyanamide, wherein the aqueous solution comprises: adding the crushed lime nitrogen and water into a hydrolysis tank for hydrolysis reaction to generate a calcium cyanamide solution, pumping the calcium cyanamide solution into a decalcification reaction tower, and introducing carbon dioxide gas into the decalcification reaction tower to obtain a calcium carbonate and cyanamide aqueous solution.
Optionally, a portion of the purified aqueous cyanamide solution of step S2 is returned to step S1 as an aqueous solution for hydrolyzing the lime nitrogen.
Optionally, heating and polymerizing the pure aqueous solution of cyanamide to obtain an aqueous solution of dicyandiamide, including: and heating and polymerizing the pure cyanamide aqueous solution under the conditions that the pH value is 8-11 and the temperature is 30-70 ℃ to obtain the dicyandiamide aqueous solution.
Optionally, filtering the aqueous solution of cyanamide to remove particles, and obtaining a pure aqueous solution of cyanamide includes: filtering out particles with the particle size larger than 0.1mm in the cyanamide aqueous solution by using a filter cloth, and then filtering out the particles with the particle size larger than 0.01mm in the cyanamide aqueous solution by using a diatomite filter under the pressure of 1kg to obtain pure cyanamide aqueous solution.
Optionally, filtering, cooling, filtering, and drying the dicyandiamide aqueous solution to obtain dicyandiamide crystals includes: filtering out particles with the particle size larger than 0.1mm in the dicyandiamide aqueous solution at 65-70 ℃ by using filter cloth, filtering out the particles with the particle size larger than 0.01mm in the dicyandiamide aqueous solution at 65-70 ℃ under the pressure of 1kg by using a diatomite filter, cooling and filtering at 30-40 ℃ to obtain wet dicyandiamide crystals, and drying the wet dicyandiamide crystals to obtain the dicyandiamide crystals.
Optionally, the dicyandiamide aqueous solution after being filtered, cooled, filtered and dried is returned to the hydrolysis tank to hydrolyze the lime nitrogen.
The application provides a dicyandiamide preparation method, which comprises the steps of mixing lime nitrogen and water for hydrolysis reaction, and introducing carbon dioxide for decalcification reaction to obtain calcium carbonate and a cyandiamide aqueous solution; filtering the cyanamide aqueous solution, and filtering out particles to obtain pure cyanamide aqueous solution; heating and polymerizing the pure cyanamide aqueous solution to obtain a dicyandiamide aqueous solution; and filtering, cooling, filtering and drying the dicyandiamide aqueous solution to obtain dicyandiamide crystals. By adopting the method, impurities such as calcium oxide, calcium hydroxide, calcium carbonate and the like in the dicyandiamide are removed, and the quality of the dicyandiamide product is improved.
Drawings
In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flow chart of a method for preparing dicyandiamide according to an embodiment of the present disclosure.
Detailed Description
The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.
Referring to fig. 1, fig. 1 shows a flow chart of a method for preparing dicyandiamide provided in this application, which can remove impurities such as calcium oxide, calcium hydroxide, and calcium carbonate in dicyandiamide, and improve the quality of dicyandiamide products.
Example 1
A method for preparing dicyandiamide, which is characterized by comprising the following steps:
step S11: mixing lime nitrogen and water for hydrolysis reaction, and introducing carbon dioxide for decalcification reaction to obtain calcium carbonate and cyanamide aqueous solution;
step S12: filtering the cyanamide aqueous solution, and filtering out particles to obtain pure cyanamide aqueous solution;
step S13: heating and polymerizing the pure cyanamide aqueous solution to obtain a dicyandiamide aqueous solution;
step S14: and filtering, cooling, filtering and drying the dicyandiamide aqueous solution to obtain dicyandiamide crystals.
Example 2
Step S21: mixing lime nitrogen and water for hydrolysis reaction, and introducing carbon dioxide for decalcification reaction to obtain calcium carbonate and cyanamide aqueous solution;
step S22: filtering out particles with the particle size larger than 0.1mm in the cyanamide aqueous solution by using a filter cloth, and then filtering out the particles with the particle size larger than 0.01mm in the cyanamide aqueous solution by using a diatomite filter under the pressure of 1kg to obtain pure cyanamide aqueous solution;
step S23: heating and polymerizing the pure cyanamide aqueous solution to obtain a dicyandiamide aqueous solution;
step S24: and filtering, cooling, filtering and drying the dicyandiamide aqueous solution to obtain dicyandiamide crystals.
Example 3
Step S31: mixing lime nitrogen and water for hydrolysis reaction, and introducing carbon dioxide for decalcification reaction to obtain calcium carbonate and cyanamide aqueous solution;
step S32: filtering out particles with the particle size larger than 0.1mm in the cyanamide aqueous solution by using a filter cloth, and then filtering out the particles with the particle size larger than 0.01mm in the cyanamide aqueous solution by using a diatomite filter under the pressure of 1kg to obtain pure cyanamide aqueous solution;
step S33: heating and polymerizing the pure cyanamide aqueous solution under the conditions that the pH value is 8 and the temperature is 30 ℃ to obtain a dicyandiamide aqueous solution;
step S34: and filtering, cooling, filtering and drying the dicyandiamide aqueous solution to obtain dicyandiamide crystals.
Example 4
Step S41: mixing lime nitrogen and water for hydrolysis reaction, and introducing carbon dioxide for decalcification reaction to obtain calcium carbonate and cyanamide aqueous solution;
step S42: filtering out particles with the particle size larger than 0.1mm in the cyanamide aqueous solution by using a filter cloth, and then filtering out the particles with the particle size larger than 0.01mm in the cyanamide aqueous solution by using a diatomite filter under the pressure of 1kg to obtain pure cyanamide aqueous solution;
step S43: heating and polymerizing the pure cyanamide aqueous solution under the conditions that the pH value is 8 and the temperature is 70 ℃ to obtain a dicyandiamide aqueous solution;
step S44: and filtering, cooling, filtering and drying the dicyandiamide aqueous solution to obtain dicyandiamide crystals.
Example 5
Step S51: mixing lime nitrogen and water for hydrolysis reaction, and introducing carbon dioxide for decalcification reaction to obtain calcium carbonate and cyanamide aqueous solution;
step S52: filtering out particles with the particle size larger than 0.1mm in the cyanamide aqueous solution by using a filter cloth, and then filtering out the particles with the particle size larger than 0.01mm in the cyanamide aqueous solution by using a diatomite filter under the pressure of 1kg to obtain pure cyanamide aqueous solution;
step S53: heating and polymerizing the pure cyanamide aqueous solution under the conditions that the pH value is 11 and the temperature is 30 ℃ to obtain a dicyandiamide aqueous solution;
step S54: and filtering, cooling, filtering and drying the dicyandiamide aqueous solution to obtain dicyandiamide crystals.
Example 6
Step S61: mixing lime nitrogen and water for hydrolysis reaction, and introducing carbon dioxide for decalcification reaction to obtain calcium carbonate and cyanamide aqueous solution;
step S62: filtering out particles with the particle size larger than 0.1mm in the cyanamide aqueous solution by using a filter cloth, and then filtering out the particles with the particle size larger than 0.01mm in the cyanamide aqueous solution by using a diatomite filter under the pressure of 1kg to obtain pure cyanamide aqueous solution;
step S63: heating and polymerizing the pure cyanamide aqueous solution at the conditions of pH value of 11 and temperature of 70 ℃ to obtain a dicyandiamide aqueous solution;
step S64: and filtering, cooling, filtering and drying the dicyandiamide aqueous solution to obtain dicyandiamide crystals.
Example 7
Step S71: mixing lime nitrogen and water for hydrolysis reaction, and introducing carbon dioxide for decalcification reaction to obtain calcium carbonate and cyanamide aqueous solution;
step S72: filtering out particles with the particle size larger than 0.1mm in the cyanamide aqueous solution by using a filter cloth, and then filtering out the particles with the particle size larger than 0.01mm in the cyanamide aqueous solution by using a diatomite filter under the pressure of 1kg to obtain pure cyanamide aqueous solution;
step S73: heating and polymerizing the pure cyanamide aqueous solution under the conditions that the pH value is 8 and the temperature is 30 ℃ to obtain a dicyandiamide aqueous solution;
step S74: filtering, cooling, filtering and drying the dicyandiamide aqueous solution to obtain dicyandiamide crystals, wherein the dicyandiamide crystals comprise: filtering out particles with the particle size larger than 0.1mm in the dicyandiamide aqueous solution at 65 ℃ by using a filter cloth, filtering out the particles with the particle size larger than 0.01mm in the dicyandiamide aqueous solution at 65 ℃ and 1kg by using a diatomite filter, cooling and filtering at 30 ℃ to obtain wet dicyandiamide crystals, and drying the wet dicyandiamide crystals to obtain the dicyandiamide crystals.
Example 8
Step S81: mixing lime nitrogen and water for hydrolysis reaction, and introducing carbon dioxide for decalcification reaction to obtain calcium carbonate and cyanamide aqueous solution;
step S82: filtering out particles with the particle size larger than 0.1mm in the cyanamide aqueous solution by using a filter cloth, and then filtering out the particles with the particle size larger than 0.01mm in the cyanamide aqueous solution by using a diatomite filter under the pressure of 1kg to obtain pure cyanamide aqueous solution;
step S83: heating and polymerizing the pure cyanamide aqueous solution at the conditions of pH value of 11 and temperature of 70 ℃ to obtain a dicyandiamide aqueous solution;
step S84: filtering, cooling, filtering and drying the dicyandiamide aqueous solution to obtain dicyandiamide crystals, wherein the dicyandiamide crystals comprise: filtering out particles with the particle size larger than 0.1mm in the dicyandiamide aqueous solution at 70 ℃ by using a filter cloth, filtering out the particles with the particle size larger than 0.01mm in the dicyandiamide aqueous solution at 70 ℃ and 1kg by using a diatomite filter, cooling and filtering at 30 ℃ to obtain wet dicyandiamide crystals, and drying the wet dicyandiamide crystals to obtain the dicyandiamide crystals.
Example 9
Step S91: mixing lime nitrogen and water for hydrolysis reaction, and introducing carbon dioxide for decalcification reaction to obtain calcium carbonate and cyanamide aqueous solution;
step S92: filtering out particles with the particle size larger than 0.1mm in the cyanamide aqueous solution by using a filter cloth, and then filtering out the particles with the particle size larger than 0.01mm in the cyanamide aqueous solution by using a diatomite filter under the pressure of 1kg to obtain pure cyanamide aqueous solution;
step S93: heating and polymerizing the pure cyanamide aqueous solution under the conditions that the pH value is 8 and the temperature is 70 ℃ to obtain a dicyandiamide aqueous solution;
step S94: filtering, cooling, filtering and drying the dicyandiamide aqueous solution to obtain dicyandiamide crystals, wherein the dicyandiamide crystals comprise: filtering out particles with the particle size larger than 0.1mm in the dicyandiamide aqueous solution at 65 ℃ by using a filter cloth, filtering out the particles with the particle size larger than 0.01mm in the dicyandiamide aqueous solution at 70 ℃ and 1kg by using a diatomite filter, cooling and filtering at 40 ℃ to obtain wet dicyandiamide crystals, and drying the wet dicyandiamide crystals to obtain the dicyandiamide crystals.
The present application has been described in detail with reference to specific embodiments and illustrative examples, but the description is not intended to limit the application. Those skilled in the art will appreciate that various equivalent substitutions, modifications or improvements may be made to the presently disclosed embodiments and implementations thereof without departing from the spirit and scope of the present disclosure, and these fall within the scope of the present disclosure. The protection scope of this application is subject to the appended claims.
Claims (7)
1. A method for preparing dicyandiamide, which is characterized by comprising the following steps:
s1: mixing lime nitrogen and water for hydrolysis reaction, and introducing carbon dioxide for decalcification reaction to obtain calcium carbonate and cyanamide aqueous solution;
s2: filtering the cyanamide aqueous solution, and filtering out particles to obtain pure cyanamide aqueous solution;
s3: heating and polymerizing the pure cyanamide aqueous solution to obtain a dicyandiamide aqueous solution;
s4: and filtering, cooling, filtering and drying the dicyandiamide aqueous solution to obtain dicyandiamide crystals.
2. The method for preparing dicyandiamide according to claim 1, wherein the steps of mixing lime nitrogen and water for hydrolysis reaction, and introducing carbon dioxide for decalcification reaction to obtain an aqueous solution of calcium carbonate and cyanamide comprise: adding the crushed lime nitrogen and water into a hydrolysis tank for hydrolysis reaction to generate a calcium cyanamide solution, pumping the calcium cyanamide solution into a decalcification reaction tower, and introducing carbon dioxide gas into the decalcification reaction tower to obtain a calcium carbonate and cyanamide aqueous solution.
3. The method for producing dicyandiamide of claim 1, wherein a part of the pure aqueous solution of cyanamide in step S2 is returned to step S1 as the aqueous solution for hydrolyzing the lime nitrogen.
4. The method for producing dicyandiamide according to claim 1, wherein the heating polymerization of the pure aqueous dicyandiamide solution to obtain the aqueous dicyandiamide solution comprises: and heating and polymerizing the pure cyanamide aqueous solution under the conditions that the pH value is 8-11 and the temperature is 30-70 ℃ to obtain the dicyandiamide aqueous solution.
5. The method for preparing dicyandiamide according to claim 1, wherein filtering the aqueous solution of cyanamide to remove particles to obtain a pure aqueous solution of cyanamide comprises: filtering out particles with the particle size larger than 0.1mm in the cyanamide aqueous solution by using a filter cloth, and then filtering out the particles with the particle size larger than 0.01mm in the cyanamide aqueous solution by using a diatomite filter under the pressure of 1kg to obtain pure cyanamide aqueous solution.
6. The method for producing dicyandiamide according to claim 2, wherein the step of filtering, cooling, filtering and drying the aqueous dicyandiamide solution to obtain dicyandiamide crystals comprises: filtering out particles with the particle size larger than 0.1mm in the dicyandiamide aqueous solution at 65-70 ℃ by using filter cloth, filtering out the particles with the particle size larger than 0.01mm in the dicyandiamide aqueous solution at 65-70 ℃ under the pressure of 1kg by using a diatomite filter, cooling and filtering at 30-40 ℃ to obtain wet dicyandiamide crystals, and drying the wet dicyandiamide crystals to obtain the dicyandiamide crystals.
7. The method according to claim 6, wherein the filtered, cooled, filtered and dried aqueous solution of dicyandiamide is returned to the hydrolysis tank to hydrolyze the lime nitrogen.
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| CN113511988A (en) * | 2021-08-20 | 2021-10-19 | 四川金象赛瑞化工股份有限公司 | System and method for preparing dicyandiamide by using urea |
| CN113527144A (en) * | 2021-08-06 | 2021-10-22 | 四川金象赛瑞化工股份有限公司 | Production method of cyanamide |
| CN114105827A (en) * | 2022-01-27 | 2022-03-01 | 天津凯莱英医药科技发展有限公司 | System and method for continuously synthesizing dicyandiamide |
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Application publication date: 20210112 |