阅读说明：本技术 一种利用含镁废水制备镁基阻燃剂的方法 (Method for preparing magnesium-based flame retardant by using magnesium-containing wastewater ) 是由 吕亮 徐继农 王璐明 李建光 王玉林 吕一锋 徐忠明 于 2020-11-24 设计创作，主要内容包括：本发明公开了一种利用含镁废水制备镁基阻燃剂的方法,包括下述步骤：(1)在格氏含镁废水中加入含铝化合物充分搅拌反应0.5-3 h,降低废水溶液的酸性,使pH值达到3-4,过滤不溶物套用于下一批反应；(2)再按一定比例补充加入可溶性铝盐,使铝离子的物质的量为镁离子的物质的量的1/4-1/2,搅拌溶解得镁铝金属盐的混合溶液A；(3)将氢氧化钠和碳酸钠按一定比例配置碱性混合溶液B；(4)将上述两种溶液A和B快速混合共沉淀制得镁铝复合氢氧化物浆料,再在60-100℃下晶化3-36 h,离心过滤、洗涤、干燥,得到镁基阻燃剂。本发明充分利用了格氏含镁废水中的镁资源,得到的镁基阻燃剂具有广泛的用途,具有环境友好、资源综合利用等优点,和良好的工业化前景。(The invention discloses a method for preparing a magnesium-based flame retardant by using magnesium-containing wastewater, which comprises the following steps: (1) adding an aluminum-containing compound into the Grignard magnesium-containing wastewater, fully stirring and reacting for 0.5-3 h, reducing the acidity of the wastewater solution to make the pH value reach 3-4, and filtering insoluble substances to be used for the next batch of reaction; (2) then adding soluble aluminum salt according to a certain proportion to make the amount of the aluminum ion substance be 1/4-1/2 of the amount of the magnesium ion substance, stirring and dissolving to obtain a mixed solution A of magnesium aluminum metal salt; (3) preparing an alkaline mixed solution B from sodium hydroxide and sodium carbonate according to a certain proportion; (4) and (3) quickly mixing and coprecipitating the two solutions A and B to prepare magnesium-aluminum composite hydroxide slurry, crystallizing for 3-36 hours at the temperature of 60-100 ℃, and performing centrifugal filtration, washing and drying to obtain the magnesium-based flame retardant. The invention fully utilizes the magnesium resource in the Grignard magnesium-containing wastewater, and the obtained magnesium-based flame retardant has wide application, has the advantages of environmental friendliness, comprehensive utilization of resources and the like, and has good industrialization prospect.)

1. A method for preparing a magnesium-based flame retardant by using magnesium-containing wastewater is characterized by comprising the following steps: the method comprises the following steps of taking Grignard magnesium-containing wastewater as a raw material, adding an aluminum source, and then carrying out coprecipitation by using alkali to prepare the magnesium-based flame retardant:

(l) Adding an aluminum-containing compound into the magnesium-containing wastewater, fully stirring and reacting for 0.5-3 h, reducing the acidity of the wastewater solution to make the pH value reach 3-4, and filtering insoluble substances to be used for the next batch of reaction;

(2) adding soluble aluminum salt into the filtrate obtained in the step (1) according to a certain proportion to enable the amount of aluminum ions to be 1/4-1/2 of the amount of magnesium ions, and stirring and dissolving to obtain a mixed solution A of magnesium-aluminum double metal salt;

(3) preparing an alkaline mixed solution B from sodium hydroxide and sodium carbonate according to a certain proportion;

(4) and (3) quickly mixing and coprecipitating the two solutions A and B to prepare magnesium-aluminum composite hydroxide slurry, crystallizing for a certain time at a certain temperature, and performing centrifugal filtration, washing and drying to obtain the magnesium-based flame retardant.

2. The method of preparing a magnesium-based flame retardant according to claim 1, wherein: in the step (1), the aluminum-containing compound is one or two of pseudo-boehmite, aluminum hydroxide and aluminum trioxide.

3. The method of preparing a magnesium-based flame retardant according to claim 1, wherein: in the step (2), the soluble aluminum salt is one or two of aluminum chloride, aluminum nitrate, aluminum sulfate and sodium aluminate.

4. The method of preparing a magnesium-based flame retardant according to claim 1, wherein: in the step (2), the adding amount of the soluble aluminum salt is 1/4-1/2 of the amount of the substance of the aluminum ion in the mixed solution as the substance of the magnesium ion.

5. The method of preparing a magnesium-based flame retardant according to claim 1, wherein: in the step (2), the mass ratio of sodium carbonate to sodium hydroxide in the prepared alkaline solution is 0:1-2: 1.

6. The method of preparing a magnesium-based flame retardant according to claim 1, wherein: in the step (3), the crystallization temperature of the obtained slurry is 60-100 ℃.

7. The method of preparing a magnesium-based flame retardant according to claim 1, wherein: in the step (3), the crystallization time of the obtained slurry is 3-36 h.

Technical Field

The invention belongs to the field of waste water resource utilization, particularly relates to comprehensive utilization of magnesium resources in magnesium-containing waste water, and particularly provides a method for preparing a magnesium-based flame retardant by utilizing the magnesium-containing waste water.

Background

The Grignard reaction is widely applied to the synthesis of products with high added value, such as medicines, spices, special organic silicon monomers and the like. Can form a large amount of magnesium waste water in the Grignard reaction process, the waste water has strong acid nature, emptys everywhere and can cause environmental pollution, emptys in a large number and can influence soil acidity and alkalinity, changes soil property, and quality of water also can change greatly. The wastewater has high salt content, dissolves partial organic matters, has high COD content, low biodegradability and great treatment difficulty. The magnesium salt content in the waste water is about 20-30%, and the direct discharge causes serious environmental pollution and waste of magnesium resources.

At present, few research reports aiming at resource utilization of magnesium ions in Grignard wastewater are limited to concentration to obtain magnesium salts or precipitation separation by adding alkali. CN200410073583 discloses recovering magnesium ions by generating magnesium sulfate, in the recovery process, a large amount of wastewater needs to be concentrated first, then concentrated sulfuric acid is added to generate magnesium sulfate, high energy consumption is needed, and the concentrated sulfuric acid causes severe corrosion to equipment. CN101130485 discloses recovering magnesium ions by generating magnesium chloride, which is a water-soluble salt, the wastewater needs to be completely evaporated to dryness, the energy consumption is high, and meanwhile, the obtained magnesium chloride often contains organic impurities, and the use of the magnesium chloride is limited due to low purity. CN101665258 discloses a process for recovering magnesium salts from grignard waste water, firstly adjusting the pH value of the waste water with alkali metal hydroxide, then adding carbonate for precipitation to obtain basic magnesium carbonate, thereby avoiding the problem of difficult solid-liquid separation of colloidal magnesium hydroxide precipitate formed by direct precipitation.

From the research results reported in the prior art, the method focuses on how to precipitate or evaporate magnesium ions to obtain a crude magnesium salt product, does not fully consider the final use and product value of the obtained product, and has little practical significance. If magnesium ions in the Grignard waste water are prepared into the magnesium-aluminum composite hydroxide, the magnesium-aluminum composite hydroxide has wide application, particularly has good characteristics on flame retardance of polyolefin, and has huge market prospect along with non-halogenation application and popularization of the flame retardant.

Aiming at the technical problems in the prior art, the invention provides a method for efficiently utilizing magnesium resources in Grignard waste water, which converts magnesium salts in the Grignard waste water into a magnesium-based flame retardant with wide application, has the advantages of low alkali consumption, low cost and high product added value, reduces the salt concentration in the waste water and improves the biodegradability while obtaining the magnesium-based flame retardant, and can be simply and conveniently treated to reach the emission standard.

Disclosure of Invention

The invention aims to provide a method for efficiently utilizing magnesium resources in magnesium-containing wastewater, and a method for converting magnesium salts in Grignard wastewater into magnesium-based flame retardants.

The technical scheme adopted by the invention is as follows: a method for preparing a magnesium-based flame retardant by using magnesium-containing wastewater comprises the following steps:

(l) Adding an aluminum-containing compound into the magnesium-containing wastewater, fully stirring and reacting for 0.5-3 h, reducing the acidity of the wastewater solution to make the pH value reach 3-4, and filtering insoluble substances to be used for the next batch of reaction;

(2) adding soluble aluminum salt into the filtrate obtained in the step (1) according to a certain proportion to enable the amount of aluminum ions to be 1/4-1/2 of the amount of magnesium ions, and stirring and dissolving to obtain a mixed solution A of magnesium-aluminum double metal salt;

(3) preparing an alkaline mixed solution B from sodium hydroxide and sodium carbonate according to a certain proportion;

(4) and (3) quickly mixing and coprecipitating the two solutions A and B to prepare magnesium-aluminum composite hydroxide slurry, crystallizing for a certain time at a certain temperature, and performing centrifugal filtration, washing and drying to obtain the magnesium-based flame retardant.

The aluminum-containing compound is preferably one or two of pseudo-boehmite, aluminum hydroxide and aluminum trioxide.

The soluble aluminum salt is preferably one or two of aluminum chloride, aluminum nitrate, aluminum sulfate and sodium aluminate.

Mg in the solution A²⁺With Al³⁺Preferably in a molar ratio of 2:1 to 4: 1.

The mass ratio of sodium carbonate to sodium hydroxide in the alkaline solution B is preferably 0:1 to 1: 1.

The slurry crystallization temperature is preferably 60 to 100 ℃.

The crystallization time of the slurry is preferably 3-36 h.

Compared with the prior art, the invention has the following advantages:

the magnesium salt in the magnesium-containing wastewater can be converted into the widely applied magnesium-based flame retardant by adopting a coprecipitation method, the method has the advantages of low alkali consumption, simple process, low treatment cost and high product added value, the magnesium-based flame retardant is obtained, the salt concentration in the wastewater is reduced, the biodegradability is improved, and the magnesium-based flame retardant can be simply and conveniently treated to reach the emission standard.

Detailed Description

The present invention is described in further detail below with reference to specific examples, but the scope of the present invention is not limited thereto.

Mg in magnesium-containing wastewater used in examples²⁺Is present in an amount of about 3.0mol/L and has a pH of about-0.48.

Example 1

A method for preparing a magnesium-based flame retardant by using magnesium-containing wastewater comprises the following steps:

(1) adding 15.6g of aluminum hydroxide into 200ml of magnesium-containing wastewater, fully stirring and reacting for 3 hours, reducing the acidity of the wastewater solution to enable the pH value to reach 3-4, and filtering out 3.9g of insoluble substances to be applied to the next batch of reaction;

(2) adding 12.07 parts of the filtrate obtained in the step (1)g aluminum chloride hexahydrate to obtain a mixed solution A, and adding Mg in the mixed solution A²⁺With Al³⁺In a molar ratio of 3: 1;

(3) adding 58.3 g of sodium carbonate and 22g of sodium hydroxide into 200ml of water to prepare an alkaline mixed solution B;

(4) and (3) quickly mixing and coprecipitating the two solutions A and B to prepare magnesium-aluminum composite hydroxide slurry, then keeping the crystallization at 65 ℃ for 24 hours, centrifugally filtering, washing and drying to obtain 60.2g of magnesium-based flame retardant with the magnesium-aluminum ratio of 3.

Example 2

A method for preparing a magnesium-based flame retardant by using magnesium-containing wastewater comprises the following steps:

(1) adding 15.6g of pseudo-boehmite into 200ml of magnesium-containing wastewater, fully stirring for reaction for 3 h, reducing the acidity of the wastewater solution to enable the pH value to reach 3-4, and filtering out 1.56g of insoluble substances to be applied to the next batch of reaction;

(2) 45.01g of aluminum nitrate nonahydrate was added to the filtrate obtained in step (1) to obtain a mixed solution A, and Mg was added to the mixed solution A²⁺With Al³⁺In a molar ratio of 2: 1;

(3) adding 15.9 g of sodium carbonate and 36g of sodium hydroxide into 200ml of water to prepare an alkaline mixed solution B;

(4) and (3) quickly mixing and coprecipitating the two solutions A and B to prepare magnesium-aluminum composite hydroxide slurry, then keeping the crystallization at 65 ℃ for 24 hours, centrifugally filtering, washing and drying to obtain 83.7g of the magnesium-based flame retardant with the magnesium-aluminum ratio of 3.

Example 3

A method for preparing a magnesium-based flame retardant by using magnesium-containing wastewater comprises the following steps:

(1) adding 7.65g of aluminum oxide into 200ml of Grignard wastewater, fully stirring for reaction for 3 h, reducing the acidity of the wastewater solution to enable the pH value to reach 3-4, and filtering out 3.05g of insoluble substances for the next batch of reaction;

(2) adding 14.48g of aluminum chloride hexahydrate into the filtrate obtained in the step (1) to obtain a mixed solution A, and adding Mg into the mixed solution A²⁺With Al³⁺In a molar ratio of 4: 1;

(3) adding 30.9 g of sodium carbonate and 30g of sodium hydroxide into 200ml of water to prepare an alkaline mixed solution B;

(4) and (3) quickly mixing and coprecipitating the two solutions A and B to prepare magnesium-aluminum composite hydroxide slurry, then keeping the crystallization at the temperature of 80 ℃ for 16 hours, and centrifugally filtering, washing and drying to obtain 50.4g of magnesium-based flame retardant with the magnesium-aluminum ratio of 4.

Example 4

A method for preparing a magnesium-based flame retardant by using magnesium-containing wastewater comprises the following steps:

(1) adding 62.4g of aluminum hydroxide into 1L of magnesium-containing wastewater, fully stirring and reacting for 3 hours, and reducing the acidity of the wastewater solution to enable the pH value to reach 3-4;

(2) adding 74.36g of aluminum chloride hexahydrate into the filtrate obtained in the step (1) to obtain a mixed solution A, and enabling Mg in the mixed solution A to be contained²⁺With Al³⁺In a molar ratio of 3: 1;

(3) adding 128g of sodium hydroxide into 1L of water to prepare a mixed solution B;

(4) and (3) quickly mixing and coprecipitating the two solutions A and B to prepare magnesium-aluminum composite hydroxide slurry, then keeping the crystallization at 90 ℃ for 12 hours, centrifugally filtering, washing and drying to obtain 410.8g of the magnesium-based flame retardant with the magnesium-aluminum ratio of 3.

Example 5

A method for preparing a magnesium-based flame retardant by using magnesium-containing wastewater comprises the following steps:

(1) adding 4.68Kg of pseudoboehmite and 1.23Kg of sodium metaaluminate into 100L of Grignard wastewater, stirring and dissolving uniformly to obtain a mixed solution A, wherein Mg in the mixed solution A is²⁺With Al³⁺In a molar ratio of 4: 1;

(2) adding 23.2Kg of sodium hydroxide into 100L of water to prepare a mixed solution B for later use;

(3) and (3) quickly mixing and coprecipitating the two solutions A and B to prepare magnesium-aluminum composite hydroxide slurry, keeping the temperature of 100 ℃ for crystallization for 6 hours, filtering the reaction solution, washing a filter cake to be alkalescent or neutral by pure water, and drying to obtain 10.2Kg of magnesium-based flame retardant with the magnesium-aluminum ratio of 4.