Method of preparing cyanamide aqueous solution and dicyandiamide and coproducing carbon and calcium carbonate by calcium cyanamide
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A cyanamide, aqueous solution technology, applied in the direction of calcium carbonate/strontium/barium, organic chemistry, etc., can solve the problem that dicyandiamide is difficult to deal with industrial waste residues and the like
Inactive Publication Date: 2009-09-09
芮海平 +1
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[0017] In order to solve the problem in the prior art of using lime nitrogen as raw material to produce cyanamide aqueous solution and dicyandiamide to produce difficult-to-handle industrial waste, the present invention aims to provide a kind of industrial lime nitrogen as raw material, which contains cyanide in its composition A production method in which nitrogen (effective nitrogen), calcium, carbon, etc. in the amine state are separately co-produced in the form of cyanamide solution or dicyandiamide, calcium carbonate, and carbon
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Embodiment 1
[0074] Example 1 Using 5% aqueous cyanamide solution, batch hydrolysis example
[0075] Into the 500mL beaker equipped with stirring, add 200g (pH7.5) of 5.00% cyanamide aqueous solution, and cool outside the beaker. Under the condition of stirring, add 10g of lime nitrogen at one time. The temperature in the beaker was kept below 20°C. After 10 minutes, the stirring was stopped, and the resultant was vacuum filtered with a Buchner funnel covered with filter paper with a diameter of 10 cm. The insoluble matter on the filter paper was washed with a small amount of water, and the filtrates were combined.
[0076] The main component of the remaining insoluble matter on the filter paper is carbon, weighing 2.83g, containing 30% water, and containing 0.17% available nitrogen. The black matter on the filter paper was first treated with 5% sodium hydroxide, then washed with water, treated with 5% nitric acid, washed with water, refined and dried to obtain 1.17 g of black carbon co...
Embodiment 2
[0102] Embodiment 2 Use the aqueous cyanamide solution obtained in Example 1 to carry out batch hydrolysis examples
[0103] Use the cyandiamide aqueous solution of example 1 gained, according to the same operating method of embodiment 2, final available cyanamide concentration 6.57%, the solution 220g of dicyandiamide concentration 0.65%. Using the material balance calculation method of Example 1 above, the dissolution efficiency is 98.0%.
[0104] Implementing this batch operation method cyclically can obtain a higher concentration of cyanamide aqueous solution.
Embodiment 3
[0105] Embodiment 3 Use 25% cyanamide aqueous solution, batch production cyanamide aqueous solution, dicyandiamide, co-production carbon and calcium carbonate
[0106] Add 200Kg of 25.00% cyanamide aqueous solution (pH10) to the 500L reactor equipped with stirring, circulate the normal temperature water outside the reactor for cooling, and add 25Kg of lime nitrogen at one time while stirring. The temperature in the kettle is kept below 40°C, and the cyanamide of the reaction solution is extracted at intervals to judge whether the reaction is complete. After about 30 minutes, the stirring is stopped, and the obtained product is transported to the drum filter, and the black insoluble matter is washed with a small amount of water. Combine the filtrates.
[0107] The main component of the insoluble matter is carbon. After acid-base refining and drying, 235Kg of black carbon components are obtained.
[0108] Lead the filtrate (mainly acidic calcium cyanamide aqueous solution) to a...
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Abstract
The method of producing cyanamide aqueous solution and dicyandiamide and co-producing carbon and calcium carbonate with lime nitrogen, adding lime nitrogen to cyanamide aqueous solution, stirring until the reaction is complete, separating insoluble matter to obtain carbon, and the weight percentage concentration of cyanamide aqueous solution 3%-30%, the reaction temperature is below 60°C, the effective nitrogen molar ratio of cyanamide to lime nitrogen in the cyanamide aqueous solution is greater than 1; carbon dioxide gas is passed through the filtrate obtained in step (a), and the precipitate is filtered to obtain calcium carbonate , the pH value during the reaction is below 10, and the reaction temperature is below 60° C.; or binary polymerizing the cyanamide aqueous solution in step (b) to obtain dicyandiamide. The method of the present invention does not produce the mixed industrial waste residue of calcium carbonate and carbon in the past, carbon and calcium carbonate are separately separated in the process of producing cyanamide aqueous solution or dicyandiamide, and the purity of the prepared calcium carbonate reaches more than 99%. The method of the present invention The reaction time is short, the dissolution efficiency is high, and the batch production yield under the same conditions is more than 50% higher than that of the prior art, and has good economic, environmental and social benefits.
Description
technical field [0001] The invention relates to a production method of cyandiamide aqueous solution and dicyandiamide, in particular to a method for producing cyandiamide aqueous solution, dicyandiamide and co-production of carbon and calcium carbonate with lime nitrogen. Background technique [0002] Cyanamide and dicyandiamide are widely used as industrial raw materials in the pesticide and pharmaceutical raw material industries, and are used as epoxy resin curing agents, dye fixing agents, flocculants, etc. Crystalline cyanamide is mainly used in the synthesis of medicines, health care products, feed additives and pesticide intermediates. The aqueous solution of cyanamide can be used as a defoliant and non-toxic insecticide for fruit trees. Dicyandiamide can be used to manufacture drugs such as guanidine salt, sulfadiazine, barbituric acid, and virus spirit; it can also be used as an organic chemical raw material in the plastics industry to produce melamine, formaldehyde ...
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