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A method for recovering and utilizing by-product hydrochloric acid in the process of preparing ADC blowing agent

A technology of ADC foaming agent and by-product hydrochloric acid, which is applied in the field of recycling by-product hydrochloric acid, can solve problems such as difficult removal of impurities, and achieve the effects of low application cost, simple and efficient treatment process, and low energy consumption

Active Publication Date: 2018-05-18
QINGHAI SALT LAKE IND
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Problems solved by technology

[0009] The object of the present invention is to provide a method for recycling by-product hydrochloric acid in the preparation process of ADC foaming agent, which is used to solve the problem of difficult removal of impurities from sodium carbonate in crude hydrazine hydrate in the preparation process of existing ADC foaming agent , at the same time, the generation of hydrochloric acid is also accompanied by the generation of hydrochloric acid in the final ADC foaming agent, how to use the generated hydrochloric acid

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  • A method for recovering and utilizing by-product hydrochloric acid in the process of preparing ADC blowing agent

Examples

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Effect test

Embodiment 1

[0029] see figure 1 , this embodiment provides a method for recycling hydrochloric acid by-product during the preparation of ADC foaming agent, including:

[0030] Pretreatment step S1 of crude hydrazine hydrate: in this embodiment, the content of sodium carbonate in the crude hydrazine hydrate solution formed by the urea method is 142g / L, and the crude hydrazine hydrate is pretreated to make the crude hydrazine hydrate The sodium carbonate content is reduced to 80-90g / L, and the liquid phase obtained after separation of the crude hydrazine hydrate is the primary hydrazine hydrate solution. The above-mentioned pretreatment operation can be a freezing method or a reaction method. The specific operation process of the freezing method is to use a cold source to lower the temperature of the crude hydrazine hydrate solution, so that it is cooled to between -2 and 0°C, so that the crude hydrazine hydrate solution part of the sodium carbonate to form sodium carbonate decahydrate cry...

Embodiment 2

[0045] see figure 1 , this embodiment provides a method for recycling hydrochloric acid by-product during the preparation of ADC foaming agent, including:

[0046] Pretreatment step S1 of crude hydrazine hydrate: In this example, the content of sodium carbonate in the crude hydrazine hydrate solution formed by the urea method is 142 g / L, and the crude hydrazine hydrate solution uses normal temperature circulating water and ethylene glycol at -15°C The aqueous solution cools it step by step, so that the crude hydrazine hydrate itself cools down to -1°C. During the cooling process of the crude hydrazine hydrate, part of the sodium carbonate forms sodium carbonate decahydrate crystals, and the crude hydrazine hydrate after freezing treatment is processed by centrifugation. Process, to separate the sodium carbonate decahydrate crystal, obtain the primary hydrazine hydrate solution that sodium carbonate content is 90g / L;

[0047] Pretreatment step S2 of by-product hydrochloric aci...

Embodiment 3

[0057] see figure 1 , this embodiment provides a method for recycling hydrochloric acid by-product during the preparation of ADC foaming agent, including:

[0058] Pretreatment step S1 of crude hydrazine hydrate: In this example, the content of sodium carbonate in the crude hydrazine hydrate solution formed by the urea method is 142 g / L, and the crude hydrazine hydrate solution uses normal temperature circulating water and ethylene glycol at -15°C The aqueous solution cools it step by step, so that the crude hydrazine hydrate itself cools down to -2°C. During the cooling process of the crude hydrazine hydrate, part of the sodium carbonate forms sodium carbonate decahydrate crystals, and the crude hydrazine hydrate after freezing treatment is subjected to centrifugal operation. Process, to separate the sodium carbonate decahydrate crystal, obtain the primary hydrazine hydrate solution that sodium carbonate content is 80g / L;

[0059] Pretreatment step S2 of by-product hydrochlo...

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Abstract

The invention discloses a method for recycling a coproduct hydrochloric acid in an ADC (azodicarbonamide) foaming agent preparation process. The method comprises the following steps: S1. pretreatment of crude hydrazine hydrate; S2. pretreatment of coproduct hydrochloric acid; S3. neutralizing treatment of primary hydrazine hydrate solution; S4. desalting treatment of secondary hydrazine hydrate solution; S5. preparation of biurea; and S6. preparation of ADC foaming agent. The coproduct hydrochloric acid produced in the step S6 is recycled, and treated by the step S2 to form hydrogen chloride gas; and the hydrogen chloride gas is introduced into the hydrazine hydrate solution in the step S3 to remove abundant sodium carbonate in the hydrazine hydrate solution, thereby implementing the cyclic utilization on the coproduct hydrochloric acid. The method solves the problem of the disposition of the coproduct hydrochloric acid, and avoids the environmental pollution caused by the hydrochloric acid. The sodium carbonate in the hydrazine hydrate solution is treated, and the formed main waste sodium chloride can be discharged to the salt field, so that the ADC foaming agent preparation process is more environment-friendly. The hydrogen chloride treatment technique is simple, and has the advantages of low energy consumption and obvious economic benefits.

Description

technical field [0001] The invention relates to the preparation of ADC foaming agent, in particular to a method for recycling by-product hydrochloric acid during the preparation of ADC foaming agent. Background technique [0002] my country is a big producer of hydrazine hydrate. Generally, 70% of the output of hydrazine hydrate is used to produce ADC blowing agent, so my country is also a big producer of ADC blowing agent. [0003] The preparation method of hydrazine hydrate in my country is generally the urea method. The chemical formula is: [0004] NH 2 CONH 2 +NaClO+NaOH→N 2 h 4 ·H 2 O+NaCl+Na 2 CO 3 , [0005] In the process of producing hydrazine hydrate by urea method, a large amount of sodium chloride and sodium carbonate by-products will be produced, so the hydrazine hydrate generated is crude hydrazine hydrate. [0006] In the process of preparing ADC foaming agent from hydrazine hydrate, the crude hydrazine hydrate needs to be converted into refined hyd...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C281/20C07C281/06C01D3/04
CPCC01D3/04C07C281/06C07C281/20
Inventor 王石军李生廷谢守帮李伟郭建荣胡成银许忠义杨万军师延满马汉晓罗永成牛小慧
Owner QINGHAI SALT LAKE IND
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