2CaCN2+2H2O→Ca(HCN2)2+Ca(OH)2
Ca(HCN2)2+CO2+H2O→2NH2CN+CaCO3
2NH2CN→(NH2CN)2
The temperature at which dicyandiamide is produced at the maximum speed is related to pH: pH is 9.7 at 50℃; At 80℃, the pH is 9.1; At 100℃, the pH value is 8.8. After polymerization under these conditions, dicyandiamide was obtained by cooling crystallization, separation and drying. The content of dicyandiamide in industrial products is 99%, and the consumption of lime nitrogen (containing more than 2 1% nitrogen) per ton of products is 4239kg.
Question 2: What is dicyandiamide? Dicyandiamide, abbreviated as DICY or DCD. It is a dimer of cyano derivatives of cyanamide and guanidine. Chemical formula C2H4N4. White crystalline powder. Soluble in water, ethanol, ethylene glycol and dimethylformamide, almost insoluble in ether and benzene. Nonflammable. Stable when dry.
Question 3: What is dicyandiamide? Calcium cyanamide suspension obtained by calcium cyanamide hydrolysis was filtered under reduced pressure to remove the filter residue of calcium hydroxide, and then carbon dioxide was introduced into the filtrate to precipitate calcium in the form of calcium carbonate to obtain calcium cyanamide solution. Polymerization under alkaline conditions, filtration, cooling, crystallization, separation and drying to obtain dicyandiamide.
The temperature at which dicyandiamide is produced at the maximum speed is related to pH: pH is 9.7 at 50℃; At 80℃, the pH is 9.1; At 100℃, the pH value is 8.8. After polymerization under these conditions, dicyandiamide was obtained by cooling crystallization, separation and drying. The content of dicyandiamide in industrial products is 99%, and the consumption of lime nitrogen (containing more than 2 1% nitrogen) per ton of products is 4239kg.
Chinese name: cyanoguanidine, dicyandiamide
English alias: dicyandiamide, cyanoguanidine
Abbreviation: DICY
HS code: 2926200000
Description: White crystalline powder. The solubility in water is 2.26% at 65438 03℃, and it is higher in hot water. When the aqueous solution is gradually decomposed at 80℃, ammonia gas is produced. At 65438 03℃, the solubility of anhydrous ethanol (C2H5OH) and ether is 65438 0.26% and 0.065438 0% respectively. Soluble in liquid ammonia, hot water, ethanol, acetone hydrate and dimethylformamide, insoluble in ether, benzene and chloroform. Relative density (d254) 1.40. The melting point is 209.5℃. The performance is stable after drying. No burning. Low toxicity, 50% lethal dose (mice, oral) > 4000mg/kg. The maximum allowable concentration in the air is 5mg/m3.
Storage: sealed, dried and preserved.
When used and stored according to the specifications, it will not decompose and avoid contact with oxides. At 65438 03℃, the solubility in absolute ethanol is 65438 0.26%, and the solubility in water is 2.26%. Dissolved in hot water, the aqueous solution will slowly decompose above 80℃ to produce ammonia. When the crystal of dichloramine is heated to the melting point, it will produce intense heat immediately after melting, resulting in melamine, melamine and so on.
Question 4: What causes dicyandiamide? Calcium carbide CaC2 reacts with N2 to generate lime hydrogen, and then the lime hydrogen is hydrolyzed to generate calcium cyanamide, and the calcium cyanamide solution is decalcified water, and finally cyanamide polymerization is completed.
Question 5: What is the urease inhibitor dicyandiamide? What I know is as follows:
Refers to a high molecular substance with biocatalysis function. In the catalytic reaction system of enzyme, the reactant molecule is called substrate, and the substrate is converted into another molecule through the catalysis of enzyme. Almost all cell activities require the participation of enzymes to improve efficiency. Similar to other non-biological catalysts, enzymes can accelerate the reaction rate by reducing the activation energy of chemical reactions (expressed by Ea or δ G), and most enzymes can increase the reaction rate catalyzed by them by millions of times. In fact, enzyme is another way to provide lower activation energy demand, so that more reaction particles can have kinetic energy not less than activation energy, thus accelerating the reaction rate. As a catalyst, the enzyme itself is not consumed in the reaction process, nor does it affect the chemical balance of the reaction. Enzymes have both positive and negative catalytic effects, which can not only accelerate the reaction rate, but also reduce the reaction rate. Different from other non-biological catalysts, enzymes are highly specific and only catalyze specific reactions or produce specific configurations.
I hope I can help you!
Question 6: Is dicyandiamide dangerous? Dicyandiamide is a dangerous chemical.
Question 7: What is dicyandiamide produced? DCD digestive inhibitor or urease inhibitor DCD digestive inhibitor
Question 8: What is the production process of dicyandiamide? Ask for a detailed explanation! Production principle and main reaction equation of 1 dicyandiamide
(1) Calcium carbide reacts with nitrogen to produce lime nitrogen.
Calcium ion +N2 = calcium ion+carbon
⑵ Lime nitrogen hydrolysis reaction
2CaCN2+2H2O=Ca(HCN2)2+Ca(OH)2
Ca(HCN2)2+2H2O=2H2CN2+Ca(OH)2
(3) decalcification of calcium cyanamide solution.
ca(HCN 2)2+2H2O+CO2 = 2h2cn 2+CaCO3
(4) cyanide polymerization
2H2CN2=(H2CN2)2
2 production process flow
Lime nitrogen is transported to the lime nitrogen storage hopper in the dicyandiamide workshop by the airflow in the lime nitrogen workshop, added into the vertical hydrolysis tank through the feeding screw, and enters the hydrolysis liquid intermediate tank after hydrolysis reaction with the mother liquid in the horizontal hydrolysis tank, then filtered, washed and separated, and the filtrate is pumped into the decalcification tower. Wet slag (water content 70%) is discharged to the slag yard for further comprehensive utilization.
The hydrolysis filtrate and carbon dioxide gas are decalcified in a decalcification tower until the PH value of the decalcified solution reaches 7.5-8. Put the material into the middle dissolving tank of decalcified liquid, add fly ash, adjust the PH value of decalcified liquid to 10 ~ 1 1, stand still, filter and wash, put the filtrate and washing liquid into cyanamide liquid tank, and discharge the filter residue into the slag yard.
Pump the cyanamide solution into the polymerization kettle, heat it with jacketed steam, control the polymerization temperature at 65 ~ 75℃, and then pump the polymerization solution into the crystallization kettle to cool and crystallize. The low-temperature water in the crystallization tank is provided by the water chiller.
The crystallization liquid enters the crystallization intermediate tank, is dried and dehydrated by a centrifuge, and the mother liquid is pumped into the mother liquid high-level tank. The wet finished product is sent to the wet finished product storage tank, dried, packaged and put into storage.
3 domestic dicyandiamide production process technology comparison
There are two processes for the production of dicyandiamide: three-step process and four-step process. The four-step method means that dicyandiamide production is divided into four main processes: hydrolysis, decalcification, polymerization and crystallization, while the three-step method combines these two processes at the same time. Compared with the four-step production process, the difference is that (1) the three-step production process is short, but the process of hydration and calcium removal is exothermic, which may increase side reactions and affect product quality. ⑵ The three-step process can only be operated intermittently, and the yield is low. (3) In the four-step method, the production waste residue produced in the hydrolysis process is lime nitrogen residue, the main component of which is calcium hydroxide, while the main component of the production waste residue produced in the decalcification process is calcium carbonate. In the three-step method, the main component of production waste residue is calcium carbonate.
At present, domestic production enterprises mostly adopt four-step production technology. In the technical transformation of dicyandiamide, the second and third sections are mainly rebuilt and expanded, and at the same time, according to the different physical properties of hydrolysis and decalcification waste residue, the environmental protection and comprehensive utilization of waste residue are developed and studied.
The filtration and washing of slag is the main bottleneck problem in dicyandiamide production at present. The production of 1 ton dicyandiamide produces about 7 tons of hydrolysis residue (mainly calcium hydroxide) and 3 tons of decalcification residue (mainly calcium carbonate). Due to the fine particle size, high alkalinity and high viscosity of dicyandiamide production waste residue, especially the calcium hydroxide in hydrolysis residue is easy to react with carbon dioxide in the air to generate calcium, which blocks the filter medium, so the filtration and washing of dicyandiamide waste residue has long been a difficult problem in dicyandiamide production.
At present, in the domestic dicyandiamide production system, vacuum filtration in sand filter tank is used to filter hydrolysis residue and decalcified residue. The main problems are: insufficient filtration capacity of equipment; ⑵ The separation effect is poor, and the water content of filter residue exceeds 55%; ⑶ The washing effect is poor. The residue of cyanamide in hydrolysis residue is 65438 0.63% (wet basis), and that in decalcification residue is 65438 0.83% (wet basis). The filtration and washing effect of slag is poor, which seriously affects the consumption and output of dicyandiamide products. The residual dicyandiamide and cyanamide in slag cause ammonia nitrogen to exceed the standard, and the slag emits a strong odor, which restricts the comprehensive application of dicyandiamide slag in environmental protection.
Question 9: What are the chemical properties of dicyandiamide? Dicyandiamide is soluble in chloroform, acetone, ethanol and liquid ammonia, slightly soluble in ether and insoluble in benzene. The solubility of 13℃ in water is 2.26%, and it is easily soluble in hot water. When the water solution is above 80℃, it slowly decomposes to produce ammonia. The solubility of dicyandiamide in absolute ethanol is 65438 0.26% at 65438 03℃. Dicyandiamide, also known as dicyandiamide, has long been used as a latent curing agent in powder coatings, adhesives and other fields.
Question 10: What is the production process of lime nitrogen and dicyandiamide? Production principle and main reaction equation of 1 dicyandiamide;
(1) Calcium carbide reacts with nitrogen to produce lime nitrogen.
Calcium ion +N2 = calcium ion+carbon
⑵ Lime nitrogen hydrolysis reaction
2CaCN2+2H2O=Ca(HCN2)2+Ca(OH)2
Ca(HCN2)2+2H2O=2H2CN2+Ca(OH)2
(3) decalcification of calcium cyanamide solution.
ca(HCN 2)2+2H2O+CO2 = 2h2cn 2+CaCO3
(4) cyanide polymerization
2H2CN2=(H2CN2)2
2 production process flow
Lime nitrogen is transported to the lime nitrogen storage hopper in the dicyandiamide workshop by the airflow in the lime nitrogen workshop, added into the vertical hydrolysis tank through the feeding screw, and enters the hydrolysis liquid intermediate tank after hydrolysis reaction with the mother liquid in the horizontal hydrolysis tank, then filtered, washed and separated, and the filtrate is pumped into the decalcification tower. Wet slag (water content 70%) is discharged to the slag yard for further comprehensive utilization.
The hydrolysis filtrate and carbon dioxide gas are decalcified in a decalcification tower until the PH value of the decalcified solution reaches 7.5-8. Put the material into the middle dissolving tank of decalcified liquid, add fly ash, adjust the PH value of decalcified liquid to 10 ~ 1 1, stand still, filter and wash, put the filtrate and washing liquid into cyanamide liquid tank, and discharge the filter residue into the slag yard.
Pump the cyanamide solution into the polymerization kettle, heat it with jacketed steam, control the polymerization temperature at 65 ~ 75℃, and then pump the polymerization solution into the crystallization kettle to cool and crystallize. The low-temperature water in the crystallization tank is provided by the water chiller.
The crystallization liquid enters the crystallization intermediate tank, is dried and dehydrated by a centrifuge, and the mother liquid is pumped into the mother liquid high-level tank. The wet finished product is sent to the wet finished product storage tank, dried, packaged and put into storage.