Process for producing biurea

A technology of biuret and hydrazine hydrate, which is applied in the field of preparation of basic carbonate, can solve the problems of by-product pollution and high energy consumption of salt and alkali, and achieve the effects of reasonable recycling, high evaporation efficiency and increasing added value.

Active Publication Date: 2008-07-16
HANGZHOU HI TECH FINE CHEM
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  • Abstract
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  • Claims
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Problems solved by technology

[0013] The purpose of the present invention is to solve the pollution problem of saline-alkali by-products and the high energy consumption problem in the production process of biuret, and ...

Method used

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  • Process for producing biurea
  • Process for producing biurea

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preparation example Construction

[0024] The preparation method of this biurea of ​​the present invention, the steps are as follows:

[0025] A) Evaporate the crude hydrazine hydrate solution prepared by the urea oxidation method through a multi-effect evaporator, and after the saline-alkali content reaches 40-60%, put the above-mentioned solution into a coulter type evaporator to continue evaporating, and control the evaporation temperature at 110- 140°C until the water and hydrazine evaporate completely to obtain a salt-free hydrazine hydrate solution and a solid saline-alkali;

[0026] B) redissolve the salt and alkali released in the coulter type evaporator, react with magnesium chloride solution, zinc sulfate or chloride solution to generate basic magnesium carbonate or basic zinc carbonate precipitation, filter and wash to obtain basic magnesium carbonate or Basic zinc carbonate;

[0027] C) After dissolving the urea in the steamed hydrazine hydrate, add sulfuric acid dropwise or connect anhydrous hydro...

Embodiment 1

[0037] Using sodium hypochlorite solution with 11.5% available chlorine content and 35% urea solution according to the molar ratio of 1:1.1, react at 100-105 ℃ in the pipeline reactor, add 32% in sections in the pipeline reactor during the reaction The sodium hydroxide solution maintains sufficient alkalinity of the reaction solution, and after the reaction is completed, the content of hydrazine hydrate in the measured reactant is 5.8%.

[0038] Put the obtained crude hydrazine hydrate solution into the two-effect tubular falling film evaporator while it is hot for distillation, control the heating temperature and feed flow rate, so that the saline and alkali content of the evaporated solution is 48-50%, and the evaporated solution enters the Coulter evaporator. The hydrazine hydrate solution continues to evaporate under stirring conditions in the coulter type evaporator, and the evaporation temperature is controlled at 110-140°C until the hydrazine hydrate evaporates complete...

Embodiment 2

[0040] Take by weighing 500 grams of saline-alkali obtained in Example 1 and be mixed with 35% solution, magnesium chloride hexahydrate (Qinghai Salt Lake Industrial Group Co., Ltd.) is mixed with 30% magnesium chloride solution, under stirring condition, magnesium chloride solution is added dropwise to saline-alkali In the solution, maintain the reaction temperature at 45°C, add magnesium chloride solution dropwise according to the equivalent of sodium carbonate and sodium hydroxide in the saline solution, continue to stir for half an hour after the dropwise addition, filter with suction, wash, and dry to obtain white powdery alkali formula magnesium carbonate 265 grams. The mother liquor after suction filtration was inspected, and there was no calcium, magnesium ion and ammonia nitrogen in the solution, which met the requirements of salt electrolysis.

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Abstract

The invention relates to a preparation method of biurea, which includes the following steps: A) a crude hydrazine hydrate liquor is evaporated through an evaporator to get a salt-free hydrazine hydrate liquor and a solid saline-alkaline; B) the ejected salt and alkali are dissolved and reacted with a magnesium chloride liquor, a sulfate of zinc and a chloride liquor to generate a precipitation of basic magnesium carbonate or a basic zinc carbonate and get the basic magnesium carbonate or the basic zinc carbonate after filtering and washing; C) an evaporated hydrazine hydrate dissolves urea, which is added with sulfate or pumped with an anhydrous hydrogen chloride to carry out a condensation reaction to generate the biurea and an ammonium sulfate or an ammonium chloride; D) the mother liquor containing the ammonium sulfate or the ammonium chloride gained through separation can acquire the ammonium sulfate or the ammonium chloride through concentration. The beneficial effects of the invention are that the invention thoroughly solves the problem of serious ammonia nitrogen pollution during the production of biurea and all the byproducts are reasonably reused and recycled; besides, the evaporation efficiency is high, which saves the amount of hydrochloride or sulfate and can avoid the overflow of raw materials caused by the large amount of bubbles in the process of neutralization.

Description

technical field [0001] The invention relates to a preparation method of basic carbonate, mainly a preparation method of biurea. Background technique [0002] Biurea, chemical name is hydrazine dicarboxamide, chemical formula is H 2 NCOHNNHCONH 2 , is a necessary intermediate for the production of azodicarbonamide foaming agent, and can also be used for the anti-skid of airstrips and the fire-proof and anti-melt of high-grade cables. [0003] As we all know, the preparation method of biurea is prepared by condensation reaction of hydrazine hydrate and urea under acidic or alkaline conditions. Due to the long condensation reaction time under alkaline conditions and the overflow of ammonia gas, all domestic manufacturers use it under acidic conditions. The following reaction, the reaction equation is as follows: [0004] [0005] Due to the hydrolysis reaction of urea, the consumption of urea is excessive, and the molar ratio of urea to hydrazine hydrate is usually 2.2-4:...

Claims

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Application Information

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IPC IPC(8): C07C281/06C07C273/18C01B21/16C01F5/24C01G9/00C01C1/16C01C1/24
Inventor 陈海贤于家波杨威
Owner HANGZHOU HI TECH FINE CHEM
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