Production method of 1, 2-dinitroguanidine

Abstract

The invention relates to the field of chemical synthesis, and particularly discloses a production method of 1, 2-dinitroguanidine, which is characterized in that ammonium nitrate, guanidine nitrate, concentrated sulfuric acid and concentrated nitric acid are used as raw materials, and continuous production of the 1, 2-dinitroguanidine is realized through the steps of synthetic reaction, nitration reaction, ice hydrolysis, filtration and neutralization, pulping, dissolution and filtration, cooling crystallization, centrifugation and the like. The production method is adjusted and optimized, the production cost is reduced, and through the continuous and informationized production method, the labor intensity is reduced, the reaction time is shortened, and the production efficiency is improved.

Description

Technical Field

[0001] The invention relates to the field of chemical synthesis, and in particular to a method for producing 1,2-dinitroguanidine. Background Art

[0002] 1,2-Dinitroguanidine has a high density (1.884 g / cm 3 ) and effective oxygen balance (+5.37%), and exhibits good explosive performance. Its use value has attracted people's attention. At the same time, some salts of the tower are also some high-energy explosives with excellent performance. 1,2-Dinitroguanidine has a structure similar to dinitrourea. The nitramine group contained in the molecule is a high-density structural unit, which is usually used as the basic design unit of other high-energy density materials.

[0003] At present, for the production of 1,2-dinitroguanidine, there is a lack of a production method with a relatively simple operating procedure, easy to control the production process, safe and reliable, and convenient for continuous operation. Summary of the invention

[0004] In view of the existing problems, a 1,2-dinitroguanidine production method is proposed to solve the problem that the existing technology lacks a set of simple operation, easy control, safe and reliable and continuous operation methods.

[0005] To achieve the above object, the present invention provides a method for producing 1,2-dinitroguanidine, the production method comprising the following steps:

[0006] S1 synthesis reaction: guanidine nitrate, ammonium nitrate and concentrated sulfuric acid are added to a primary synthesis reactor in a manner of gradually increasing the feeding amount, and a synthesis reaction occurs in the primary synthesis reactor until the maximum designed feeding rate is reached, and the temperature in the primary synthesis reactor is controlled. During the continuous feeding process, the material overflows from the primary synthesis reactor into the secondary synthesis reactor, and the temperature in the secondary synthesis reactor is controlled. The material further completes the synthesis reaction in the secondary synthesis reactor, and finally continuously overflows from the secondary synthesis reactor into the primary nitration reactor, and the synthesis reaction product is nitroguanidine;

[0007] S2 nitration reaction: after the material enters the primary nitration kettle, frozen concentrated nitric acid is added to the primary nitration kettle, and the feeding speed of the concentrated nitric acid is gradually increased until the maximum design feeding speed is reached, the temperature in the primary nitration kettle is controlled, and the material undergoes nitration reaction. During the continuous feeding process, the material overflows into the secondary nitration kettle and the tertiary nitration kettle in turn. The frozen concentrated nitric acid is added to the secondary nitration kettle by gradually increasing the feeding speed of the concentrated nitric acid until the maximum design feeding speed is reached, the temperature in the secondary nitration kettle and the tertiary nitration kettle is controlled, and the nitration reaction is deepened and completed. The nitration reaction product is 1,2-dinitroguanidine;

[0008] S3 thawing: adding recycled water to the first thawing kettle, stirring and controlling the temperature in the first thawing kettle, after the material in the third nitrification kettle overflows into the first thawing kettle, continuously adding recycled water to the first thawing kettle at a steady speed, during the continuous feeding process, the material overflows from the first thawing kettle into the second thawing kettle, controlling the temperature in the second thawing kettle, and further completing thawing;

[0009] S4 Filtration and Neutralization: The material enters the vacuum belt machine from the secondary thawing kettle, and the moisture in the material is removed by vacuum. During the filtration process, the material is sprayed with ammonium carbonate aqueous solution, and the filter cake is sent to the pulping tank. The filtrate is temporarily stored in the acid water pool and then sent to the calcium sulfate workshop for treatment;

[0010] S5 beating: the filter cake enters the beating tank, and evaporation method is added to the beating tank to form slurry while stirring;

[0011] S6 dissolution and filtration: several heating kettles are set up, the slurry is first added to the No. 1 heating kettle from the beating tank, evaporated water and centrifugal liquid are added to the No. 1 heating kettle, the temperature in the No. 1 heating kettle is increased to completely dissolve the slurry, nitrogen is charged into the No. 1 heating kettle to increase the pressure in the kettle, after the slurry in the No. 1 heating kettle reaches the designed liquid level, other heating kettles are switched, the slurry is fed from the beating tank to other heating kettles, the material in the No. 1 heating kettle is filtered through the filter and then sent to the primary crystallization kettle;

[0012] S7 cooling crystallization: after the material enters the first-stage crystallization kettle, it overflows into the second-stage crystallization kettle and the third-stage crystallization kettle in sequence, and the temperatures in the first-stage crystallization kettle, the second-stage crystallization kettle and the third-stage crystallization kettle are lowered respectively, and the solute in the material is continuously crystallized and precipitated in the crystallization kettle;

[0013] S8 centrifugation: centrifuge the material after cooling and crystallization, and the solid phase obtained by centrifugation is the finished 1,2-dinitroguanidine. The separated centrifuge liquid is sent to step S6 dissolution process to repeat cooling, crystallization and centrifugation.

[0014] Furthermore, in the synthesis reaction of step S1, the concentrations of concentrated sulfuric acid, guanidine nitrate and ammonium nitrate are 98%, 92% and 99% respectively, the temperatures of the concentrated sulfuric acid and guanidine nitrate raw materials are controlled at less than 20° C. and less than 30° C. respectively, the temperature in the first-level synthesis reactor is controlled at 32-37° C., the temperature in the second-level synthesis reactor is controlled at 30-35° C., and the molar ratio of the hourly addition amount of guanidine nitrate, concentrated sulfuric acid and ammonium nitrate is 4:8:0.3.

[0015] Furthermore, in the nitration reaction of step S2, the concentration of concentrated nitric acid is 90%, the temperature in the first-stage nitration kettle is controlled to be lower than 0°C, the temperature in the second-stage nitration kettle and the third-stage nitration kettle is controlled to be lower than 5°C, and the feeding rate of concentrated nitric acid in the second-stage nitration kettle is 1 / 5 of that in the first-stage nitration kettle.

[0016] Furthermore, in the thawing step S3, the temperature in the first-stage thawing kettle is controlled at 25-27° C., the temperature in the second-stage thawing kettle is controlled at 10-15° C., and the mass ratio of recycled water and guanidine nitrate added per hour is 15:1.

[0017] Furthermore, in step S5, the water content of the slurry is controlled at 35-37%.

[0018] Furthermore, in step S6, the feeding speed of the evaporated water and the centrifugal liquid is 1.5 to 2 times the feeding speed of the slurry, the temperature in the heating kettle is controlled at 75 to 80° C., and the pressure in the heating kettle is controlled at 0.15 to 0.2 MPa.

[0019] Furthermore, in step S7, the temperatures inside the first-stage crystallization kettle, the second-stage crystallization kettle and the third-stage crystallization kettle are controlled below 55° C., 35° C. and 5° C., respectively.

[0020] Furthermore, the water treatment process in the calcium sulphate workshop includes the following steps:

[0021] (1) beating: mixing calcium carbonate powder and filtered water in a mixing tank at a mass ratio of 1:1 to obtain calcium carbonate slurry;

[0022] (2) Neutralization: The calcium carbonate slurry overflows from the stirring tank into the primary neutralization kettle, and the filtrate produced by the filtration and neutralization in step S4 is pumped into the primary neutralization kettle to undergo a neutralization reaction with the calcium carbonate slurry to produce a neutralization reaction slurry. The neutralization reaction slurry overflows into the secondary neutralization kettle and the tertiary neutralization kettle in turn, and the filtrate is respectively pumped into the secondary neutralization kettle and the tertiary neutralization kettle for further neutralization reaction. The neutralization reaction temperature is controlled at 35 to 40° C.;

[0023] (3) Filtration: The neutralization reaction slurry is filtered using a plate and frame filter press. The filter cake is a calcium sulfate byproduct. The filtered water is temporarily stored in a low-level tank, and part of the filtered water is used for pulping in step (1);

[0024] (4) Reaction: The filter press water in the low-level tank is pumped into the primary reaction tank, and a 10% concentration of ammonium carbonate solution is injected into the primary reaction tank. The filter press water after the reaction overflows into the secondary reaction tank, and a flocculant solution is added to the secondary reaction tank, and the filter press water is circulated in the secondary reaction tank for full reaction;

[0025] (5) Filtration: The material in the secondary reaction tank is filtered through a multi-media filter. The filter cake is calcium carbonate, which is reused for pulping in step (1). The soft water produced by filtration enters a soft water tank. Part of the soft water is frozen and then used as recycled water in step S3 for thawing.

[0026] (6) Concentration: The remaining soft water is distilled at high temperature and under negative pressure, and the evaporated water is reused in the pulping step S5;

[0027] (7) Crystallization: After the concentrated high-temperature soft water is cooled, the salt solute in the soft water crystallizes out;

[0028] (8) Centrifugation: The soft water after crystallization is centrifuged to separate the centrifugal salt as a by-product, which is a mixture of ammonium nitrate and ammonium sulfate. The separated centrifugal water is returned to step (6) for concentration and repeated high-temperature negative pressure distillation.

[0029] The beneficial effects of the present invention are as follows: the present invention completes the production of 1,2-dinitroguanidine through the steps of synthesis reaction, nitration reaction, ice melting, filtration neutralization, pulping, dissolution filtration, cooling crystallization, centrifugation and the like; all waste water generated in the production process is sent to a calcium sulfate workshop for treatment; the treated water is reused in the production process, which greatly reduces the use of fresh water and basically achieves zero discharge of waste water, meeting the requirements of clean production and energy conservation and emission reduction; the production cost is reduced by adjusting and optimizing the production method; concentrated sulfuric acid is used for reaction in the production, which is relatively safer; the present invention adopts a continuous and information-based production method, reduces labor intensity, shortens reaction time and improves production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solution of the present invention, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 is a flow chart of the production method of the present invention;

[0032] Figure 2 This is a process flow chart of water treatment in the calcium sulphate workshop of the present invention. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0034] In a specific embodiment of the present invention, Figure 1 As shown, a method for producing 1,2-dinitroguanidine comprises the following steps:

[0035] S1 synthesis reaction:

[0036] (1) Start the concentrated sulfuric acid canned pump, adjust the flow rate to 1500 kg / h, and inject 5400 kg of sulfuric acid into the first-stage synthesis reactor;

[0037] (2) Start circulating chilled brine, stir for 10 min, and control the temperature of concentrated sulfuric acid below 20°C;

[0038] (3) adding guanidine nitrate to the first-stage synthesis reactor by means of a bucket elevator, wherein the initial feeding rate of guanidine nitrate is controlled to be 120 kg / h, and the feeding rate is increased to 140 kg / h after 1.5 h, and the feeding rate is gradually increased at a rate of increasing the feeding amount by 20 kg per hour, and the temperature in the first-stage synthesis reactor is controlled to be below 30° C.;

[0039] (4) After the amount of guanidine nitrate added reaches 3000 kg, stir for 30 minutes, add 145 kg of ammonium nitrate, and control the temperature in the first-stage synthesis reactor to be below 37° C.;

[0040] (5) continuously feeding into the first-stage synthesis reactor, first adding guanidine nitrate and ammonium nitrate at a rate of 133 kg / h and 8 kg / h, and adding concentrated sulfuric acid at a rate of 200 kg / h, and controlling the temperature in the first-stage synthesis reactor at 32-37° C.;

[0041] (6) After the reaction proceeds normally, the feeding amount of guanidine nitrate, ammonium nitrate and sulfuric acid is gradually increased to 530 kg / h, 24 kg / h and 800 kg / h respectively, wherein the molar ratio of the feeding amount of guanidine nitrate, sulfuric acid and ammonium nitrate per hour is 4:8:0.3, and the temperature in the first-stage synthesis reactor is controlled at 32-37° C. until the feeding amount required for this batch of production is reached;

[0042] (7) During the continuous feeding process, the material overflows from the primary synthesis reactor to the secondary synthesis reactor, the secondary synthesis reactor is stirred, the circulation of chilled brine is started, and the temperature in the secondary synthesis reactor is adjusted to 30-35° C.;

[0043] (8) During the continuous feeding process, the material in the secondary synthesis reactor flows out from the overflow port and enters the primary nitration reactor after being cooled by the cooler;

[0044] The synthetic reaction product is nitroguanidine, and the following chemical reactions mainly occur:

[0045]

[0046] S2 nitration reaction:

[0047] (1) After the material overflows into the primary nitrification kettle, start stirring, start the No. 1 concentrated nitric acid shielded pump, first add frozen 90% concentrated nitric acid at a rate of 200 kg / h, and after 1 hour, increase the concentrated nitric acid feed rate by 90 kg per hour until the concentrated nitric acid feed rate reaches 560 kg / h, start circulating frozen brine, and adjust the temperature in the primary nitrification kettle to 0°C;

[0048] (2) After the first-stage nitrification kettle continues to add materials for 4 hours, the materials overflow into the second-stage nitrification kettle, stirring is started, and the No. 2 concentrated nitric acid shielded pump is turned on. First, refrigerated 90% concentrated nitric acid is added at a rate of 40 kg / h. After 1 hour, the concentrated nitric acid addition rate is increased by 18 kg per hour until the concentrated nitric acid addition rate reaches 112 kg / h. The circulation of refrigerated brine is started, and the temperature in the second-stage nitrification kettle is adjusted to 5°C;

[0049] (3) After the secondary nitration kettle is continuously charged for 4 hours, the material overflows into the tertiary nitration kettle, stirring is started, the circulation of chilled brine is started, and the temperature in the tertiary nitration kettle is adjusted to 5°C;

[0050] The product of the nitration reaction is 1,2-dinitroguanidine, and the following chemical reactions mainly occur;

[0051]

[0052] S3 Ice Solution:

[0053] Inject 4 tons of recycled water into the first-stage thawing kettle, start stirring, start circulating frozen brine, adjust the temperature in the first-stage thawing kettle to 5°C, continue feeding the third-stage nitrification kettle for 4 hours, and let the material overflow into the first-stage thawing kettle. Start the recycled water metering pump, control the recycled water flow rate to 8 t / h, and the mass ratio of guanidine nitrate to recycled water to 1:15. Start circulating frozen brine, control the temperature of the first-stage thawing kettle to 25-27°C, and after the material overflows into the second-stage thawing kettle, control the temperature in the second-stage thawing kettle to 10-15°C;

[0054] S4 Filtration and Neutralization:

[0055] The material enters the vacuum belt conveyor from the secondary thawing kettle, and the material is evenly distributed on the filter cloth by a distributor. The moisture in the material is removed by vacuum. A 10% ammonium carbonate aqueous solution is evenly sprayed on the material at a flow rate of 10kg / h using a soda ash water metering pump. The filter cake is sent to the pulping tank, and the filtrate is sent to the calcium sulfate workshop for treatment through the acid water pool. The main component of the filter cake is 1,2-dinitroguanidine, and the main components of the filtrate are ammonium nitrate, sulfuric acid and nitric acid.

[0056] S5 beating:

[0057] The filter cake enters the beating tank, and while stirring, evaporated water is pumped in at a rate of 1080kg / h to form a slurry. The slurry is pumped into heating kettles 1 to 4 in sequence using a centrifugal pump. The discharge rate of the beating tank is about 800kg / h. The water content of the slurry is 35-37%, and the discharged material contains about 520kg of 1,2-dinitroguanidine and 280kg of water.

[0058] S6 dissolution filtration:

[0059] After 1.5 hours, the feeding of heating kettle No. 1 is finished, and the feeding of heating kettle No. 2 is switched. Evaporated water and 1.5t of centrifugal liquid are added to heating kettle No. 1, and the temperature in the kettle is increased to 75-80°C to completely dissolve the slurry. Nitrogen is charged into recrystallization kettles No. 1-3 to make the pressure in the kettle reach 0.15-0.2MPa, and the bottom valve of heating kettle No. 1 is opened, and the material is pressed and filtered through the filter and then sent to the primary crystallization kettle;

[0060] S7 cooling crystallization:

[0061] The material enters the first-stage crystallization kettle, where the material temperature is reduced to below 55°C, and the material overflows into the second-stage crystallization kettle, where the material temperature is reduced to below 35°C, and the material overflows into the third-stage crystallization kettle, where the material temperature is reduced to below 5°C. Under low temperature conditions, the solute in the material is continuously crystallized and precipitated;

[0062] S8 Centrifuge:

[0063] The cooled and crystallized material is put into a centrifuge for centrifugation. The solid phase obtained after centrifugation is the finished 1,2-dinitroguanidine product. 750-780 kg of the finished 1,2-dinitroguanidine product with a water content of 23-25% can be obtained per hour. The centrifuge liquid produced by centrifugation is returned to the dissolution and filtration process in step S6 to repeat the cooling, crystallization and centrifugation treatment.

[0064] The recycled water and evaporated water involved in the production process are part of the reusable water generated during the water treatment process of the calcium sulfide workshop. The water treatment process of the calcium sulfide workshop is as follows:

[0065] (1) Slurrying: Calcium carbonate powder and filtered water are mixed and stirred in a mixing tank at a mass ratio of 1:1 to prepare a calcium carbonate slurry, wherein the total amount of calcium carbonate powder and filtered water is 10.5 t / h;

[0066] (2) Neutralization: The filtrate generated in the filtering and neutralization process of step S4 is injected into the primary neutralization kettle, and the injection rate of the filtrate is controlled to be 60 t / h. The calcium carbonate slurry overflows from the stirring kettle into the primary neutralization kettle, and the filtrate and the calcium carbonate slurry undergo a neutralization reaction. The material overflows from the primary neutralization kettle into the secondary neutralization kettle, and the filtrate is injected into the secondary neutralization kettle at a rate of 20 t / h. The filtrate is retained in the secondary neutralization kettle for 2 hours to deepen the neutralization reaction. The material overflows from the secondary neutralization kettle into the tertiary neutralization kettle to complete the neutralization reaction. The neutralization reaction temperature is controlled at 35-40° C. The neutralization reaction products are mainly calcium sulfate, calcium nitrate and ammonium nitrate;

[0067] (3) Filter pressing: The slurry after the neutralization reaction is filtered through a plate and frame filter press by using a plate and frame delivery pump. The filter cake is a calcium sulfate byproduct with a moisture content of 15-20%. The filter press water enters a low-level tank for temporary storage, and part of the filter press water is used in the pulping process of step (1);

[0068] (4) Reaction: The filter press water in the low-level tank is pumped into the primary reaction tank, and the filter press water flow rate is controlled to be 45 t / h. The alkaline water pump is turned on to inject a 10% concentration of ammonium carbonate solution into the primary reaction tank at a rate of 250 kg / h. The pH is adjusted to 9. After 1 hour, the material overflows into the secondary reaction tank. A 0.05% concentration of flocculant solution is injected into the secondary reaction tank at a rate of 250 kg / h. The self-circulation pump of the secondary reaction tank is turned on to circulate the material;

[0069] (5) Filtration: When the liquid level in the secondary reaction tank reaches 75%, the discharge valve is opened, and the material is filtered through a multi-media filter. The filter cake is produced at a rate of 7.5 to 8 kg / h. The filter cake is mainly composed of calcium carbonate, which is reused in the pulping in step (1). The soft water produced by filtration enters the soft water tank. Part of the soft water in the soft water tank is frozen and reused as recycled water in the ice-thawing process in step S3;

[0070] (6) Concentration: The remaining soft water is distilled at high temperature and under negative pressure, and the evaporated water is reused in the pulping process in step S5;

[0071] (7) Crystallization: After the concentrated high-temperature soft water is cooled, the salt solute in the soft water crystallizes out;

[0072] (8) Centrifugation: The soft water after crystallization is centrifuged to separate the byproduct, the separated centrifugal salt is a mixture of ammonium nitrate and ammonium sulfate, with an output of about 4500 kg / d, of which about 2500 kg is ammonium nitrate and 2000 kg is ammonium sulfate. The separated centrifugal water is returned to the concentration process of step (6) to repeat the high-temperature negative pressure distillation.

[0073] In summary: the present invention provides a method for producing 1,2-dinitroguanidine, which can effectively carry out stable and continuous production of 1,2-dinitroguanidine. The production method is relatively safer and more efficient. The wastewater generated in the production is reused after treatment, and the production method is greener and cleaner.

[0074] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for producing 1,2-dinitroguanidine, characterized in that: The production method comprises the following steps: S1 synthesis reaction: guanidine nitrate, ammonium nitrate and concentrated sulfuric acid are added to a primary synthesis reactor in a manner of gradually increasing the feeding amount, and a synthesis reaction occurs in the primary synthesis reactor until the maximum designed feeding rate is reached, and the temperature in the primary synthesis reactor is controlled. During the continuous feeding process, the material overflows from the primary synthesis reactor into the secondary synthesis reactor, and the temperature in the secondary synthesis reactor is controlled. The material further completes the synthesis reaction in the secondary synthesis reactor, and finally continuously overflows from the secondary synthesis reactor into the primary nitration reactor, and the synthesis reaction product is nitroguanidine; S2 nitration reaction: after the material enters the primary nitration kettle, frozen concentrated nitric acid is added to the primary nitration kettle, and the feeding speed of the concentrated nitric acid is gradually increased until the maximum design feeding speed is reached, the temperature in the primary nitration kettle is controlled, and the material undergoes nitration reaction. During the continuous feeding process, the material overflows into the secondary nitration kettle and the tertiary nitration kettle in turn. The frozen concentrated nitric acid is added to the secondary nitration kettle by gradually increasing the feeding speed of the concentrated nitric acid until the maximum design feeding speed is reached, the temperature in the secondary nitration kettle and the tertiary nitration kettle is controlled, and the nitration reaction is deepened and completed. The nitration reaction product is 1,2-dinitroguanidine; S3 thawing: adding recycled water to the first thawing kettle, stirring and controlling the temperature in the first thawing kettle, after the material in the third nitrification kettle overflows into the first thawing kettle, continuously adding recycled water to the first thawing kettle at a steady speed, during the continuous feeding process, the material overflows from the first thawing kettle into the second thawing kettle, controlling the temperature in the second thawing kettle, and further completing thawing; S4 Filtration and Neutralization: The material enters the vacuum belt machine from the secondary thawing kettle, and the moisture in the material is removed by vacuum. During the filtration process, the material is sprayed with ammonium carbonate aqueous solution, and the filter cake is sent to the pulping tank. The filtrate is temporarily stored in the acid water pool and then sent to the calcium sulfate workshop for treatment; S5 beating: the filter cake enters the beating tank, and evaporation method is added to the beating tank to form slurry while stirring; S6 dissolution and filtration: several heating kettles are set up, the slurry is first added to the No. 1 heating kettle from the beating tank, evaporated water and centrifugal liquid are added to the No. 1 heating kettle, the temperature in the No. 1 heating kettle is increased to completely dissolve the slurry, nitrogen is charged into the No. 1 heating kettle to increase the pressure in the kettle, after the slurry in the No. 1 heating kettle reaches the designed liquid level, other heating kettles are switched, the slurry is fed from the beating tank to other heating kettles, the material in the No. 1 heating kettle is filtered through the filter and then sent to the primary crystallization kettle; S7 cooling crystallization: after the material enters the first-stage crystallization kettle, it overflows into the second-stage crystallization kettle and the third-stage crystallization kettle in sequence, and the temperatures in the first-stage crystallization kettle, the second-stage crystallization kettle and the third-stage crystallization kettle are lowered respectively, and the solute in the material is continuously crystallized and precipitated in the crystallization kettle; S8 centrifugation: centrifuge the material after cooling and crystallization, and the solid phase obtained by centrifugation is the finished 1,2-dinitroguanidine. The separated centrifuge liquid is sent to step S6 dissolution process to repeat cooling, crystallization and centrifugation.

2. A method for producing 1,2-dinitroguanidine according to claim 1, characterized in that: In the synthesis reaction of step S1, the concentrations of concentrated sulfuric acid, guanidine nitrate and ammonium nitrate are 98%, 92% and 99% respectively, the temperatures of the concentrated sulfuric acid and guanidine nitrate raw materials are controlled at less than 20° C. and less than 30° C. respectively, the temperature in the first-level synthesis reactor is controlled at 32-37° C., the temperature in the second-level synthesis reactor is controlled at 30-35° C., and the molar ratio of the hourly addition amount of guanidine nitrate, concentrated sulfuric acid and ammonium nitrate is 4:8:0.

3.

3. A method for producing 1,2-dinitroguanidine according to claim 1, characterized in that: In the nitration reaction of step S2, the concentration of concentrated nitric acid is 90%, the temperature in the first-stage nitration kettle is controlled to be lower than 0°C, the temperature in the second-stage nitration kettle and the third-stage nitration kettle is controlled to be lower than 5°C, and the feeding rate of concentrated nitric acid in the second-stage nitration kettle is 1 / 5 of that in the first-stage nitration kettle.

4. A method for producing 1,2-dinitroguanidine according to claim 1, characterized in that: In the thawing step S3, the temperature in the first-stage thawing kettle is controlled at 25-27° C., the temperature in the second-stage thawing kettle is controlled at 10-15° C., and the mass ratio of recycled water to guanidine nitrate added per hour is 15:

1.

5. A method for producing 1,2-dinitroguanidine according to claim 1, characterized in that: In step S5, the water content of the slurry is controlled at 35-37%.

6. A method for producing 1,2-dinitroguanidine according to claim 1, characterized in that: In step S6, the feeding speed of evaporated water and centrifugal liquid is 1.5 to 2 times of the feeding speed of slurry, the temperature in the heating kettle is controlled at 75 to 80° C., and the pressure in the heating kettle is controlled at 0.15 to 0.2 MPa.

7. A method for producing 1,2-dinitroguanidine according to claim 1, characterized in that: In step S7, the temperatures in the first-stage crystallization kettle, the second-stage crystallization kettle and the third-stage crystallization kettle are controlled below 55° C., 35° C. and 5° C. respectively.

8. A method for producing 1,2-dinitroguanidine according to claim 1, characterized in that: The water treatment process in the calcium sulfide workshop includes the following steps: (1) beating: mixing calcium carbonate powder and filtered water in a mixing tank at a mass ratio of 1:1 to obtain calcium carbonate slurry; (2) Neutralization: The calcium carbonate slurry overflows from the stirring tank into the primary neutralization kettle, and the filtrate produced by the filtration and neutralization in step S4 is pumped into the primary neutralization kettle to undergo a neutralization reaction with the calcium carbonate slurry to produce a neutralization reaction slurry. The neutralization reaction slurry overflows into the secondary neutralization kettle and the tertiary neutralization kettle in turn, and the filtrate is respectively pumped into the secondary neutralization kettle and the tertiary neutralization kettle for further neutralization reaction. The neutralization reaction temperature is controlled at 35 to 40° C.; (3) Filtration: The neutralization reaction slurry is filtered using a plate and frame filter press. The filter cake is a calcium sulfate byproduct. The filtered water is temporarily stored in a low-level tank, and part of the filtered water is used for pulping in step (1); (4) Reaction: The filter press water in the low-level tank is pumped into the primary reaction tank, and a 10% concentration of ammonium carbonate solution is injected into the primary reaction tank. The filter press water after the reaction overflows into the secondary reaction tank, and a flocculant solution is added to the secondary reaction tank, and the filter press water is circulated in the secondary reaction tank for full reaction; (5) Filtration: The material in the secondary reaction tank is filtered through a multi-media filter. The filter cake is calcium carbonate, which is reused for pulping in step (1). The soft water produced by filtration enters a soft water tank. Part of the soft water is frozen and then used as recycled water in step S3 for thawing. (6) Concentration: The remaining soft water is distilled at high temperature and under negative pressure, and the evaporated water is reused in the pulping step S5; (7) Crystallization: After the concentrated high-temperature soft water is cooled, the salt solute in the soft water crystallizes out; (8) Centrifugation: The soft water after crystallization is centrifuged to separate the centrifugal salt as a by-product, which is a mixture of ammonium nitrate and ammonium sulfate. The separated centrifugal water is returned to step (6) for concentration and repeated high-temperature negative pressure distillation.

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