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Preparation method of nano-level magnesium hydroxide

A magnesium hydroxide and nano-scale technology, applied in the direction of magnesium hydroxide, etc., can solve the problems of large investment in equipment, difficult product filtration and washing, and difficult maintenance of equipment, and achieve the effect of simple process, easy control of process parameters and small investment

Inactive Publication Date: 2006-05-10
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, the most widely used production process is chemical synthesis, wherein representative synthetic processes (see "Inorganic Chemical Products", edited by Jason Situ, page p320) are brine-lime method, brine-ammonia method and magnesite -hydrochloric acid-ammonia water method, but there are many deficiencies in these processes: either there is gelation phenomenon, and the finer the precipitated particles, the more serious the gelation phenomenon is, which causes great difficulties for the filtration and washing of the product; or the pH of the system The value is not easy to control, and the yield of the product is low; or the product is prone to secondary agglomeration during the precipitation and filtration process, and finally nano-scale ultrafine particles cannot be obtained
[0004] At present, there are the following invention patents disclosed on the preparation method of nano-scale magnesium hydroxide: CN1332116A uses soluble magnesium salt and alkali to synthesize magnesium hydroxide with an average particle size of 10-200nm through a homogeneous fluid method through forced precipitation reaction, The process is simple and convenient, but the particle size distribution of the gained magnesium hydroxide is relatively wide, and strictly speaking, the particle size exceeding 100nm does not belong to nanoparticles; CN1341694A is the refined magnesium chloride solution and Industrial ammonia water or ammonia gas as raw material, or use magnesium sulfate solution and industrial ammonia water or ammonia gas as raw material, adopt supergravity (rotating packed bed) technology, and use liquid-liquid phase reaction or gas-liquid phase reaction method to prepare average particle size Magnesium hydroxide between 35 and 90nm is characterized by simple process flow and uniform particle size, but requires special equipment - rotating packed bed (super gravity), and the equipment investment is relatively large; CN1356361A is oxidized with natural brucite or sintering Magnesium is used as a raw material, and the average particle size is prepared by wet crushing to produce magnesium hydroxide below 100nm. This method is the simplest, but it can only produce magnesium hydroxide with low purity requirements; The back-mixed liquid membrane reactor carries out the co-precipitation reaction of magnesium salt and lye to prepare magnesium hydroxide with an average particle size of 62-92nm. The process of this method is similar to that of CN1341694A. Equipment - the processing cost of the fully back-mixed liquid film reactor is expensive (the gap between the rotor and the stator must be controlled at 1-20 μm), and the equipment is difficult to maintain
[0005] In summary, the existing methods for preparing high-purity nano-scale magnesium hydroxide particles require special special equipment, which requires large investment and high operation and maintenance costs.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0021] First, magnesium chloride (MgCl 2 ·6H 2 (0) 50.8g is dissolved in 345g water, is mixed with the magnesium chloride aqueous solution of mass concentration about 6%, is heated to 80 ℃ standby; Another get concentration is that 25~28% ammoniacal liquor 30ml mixes with 90g water, with 40% sodium hydroxide Adjust the pH of the solution to ≈14, and heat it to 70°C for later use; prepare 150ml of ethanol aqueous solution with a mass concentration of 90%, and lower its temperature to -8°C for later use. Then, under vigorous stirring, quickly add the magnesium chloride aqueous solution into the mixed precipitant, react for 20 minutes, pour it into the ethanol aqueous solution under ultrasonic vibration, keep the low temperature for 30 minutes, and finally filter, wash and vacuum dry to obtain magnesium hydroxide. The particle size range of the product measured by the laser particle size analyzer is between 30-80nm, the average particle size is 68nm, and the purity is 99.9% as m...

Embodiment 2

[0023] First, magnesium chloride (MgCl 2 ·6H 2 (0) 50.8g is dissolved in 132g water, is mixed with the magnesium chloride aqueous solution of mass concentration about 13%, is heated to 80 ℃ standby; Another get concentration is that 25~28% ammoniacal liquor 40ml mixes with 200g water, with 40% sodium hydroxide Adjust the pH of the solution to ≈13, and heat it to 60°C for later use; prepare 200ml of ethanol aqueous solution with a mass concentration of 60%, and lower its temperature to 5°C for later use. Then, under vigorous stirring, quickly add the magnesium chloride aqueous solution to the mixed precipitant, react for 10 minutes, pour into the ethanol aqueous solution under ultrasonic vibration, keep the low temperature for 30 minutes, and finally filter, wash and vacuum dry to obtain magnesium hydroxide. The particle size range of the product measured by the laser particle size analyzer is between 30-100nm, the average particle size is 76nm, and the purity is 99.2% as meas...

Embodiment 3

[0025] First, magnesium chloride (MgCl 2 ·6H 2 (0) 50.8g is dissolved in 187g water, is mixed with the magnesium chloride aqueous solution of mass concentration about 10%, is heated to 80 ℃ standby; Another get concentration is that 25~28% ammoniacal liquor 48ml mixes with 150g water, with 40% sodium hydroxide Adjust the pH of the solution to ≈11, and heat it to 50°C for later use; prepare 180ml of ethanol aqueous solution with a mass concentration of 70%, and lower its temperature to -2°C for later use. Then, under vigorous stirring, quickly add the magnesium chloride aqueous solution to the mixed precipitant, react for 3 minutes, pour it into the ethanol aqueous solution under ultrasonic vibration, keep the low temperature for 30 minutes, and finally filter, wash and vacuum dry to obtain magnesium hydroxide. The particle size range of the product measured by the laser particle size analyzer is between 40-95nm, the average particle size is 72nm, and the purity is 99.3% as me...

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Abstract

The preparation method of nano-scale magnesium hydroxide provided by the present invention is to control particle size by crystal formation and growth mechanism, use magnesium salt solution as raw material, and use sodium hydroxide and ammonia water as mixed precipitating agent to prepare nano-scale hydrogen by reverse precipitation method Magnesium oxide. The invention does not need special equipment and requires little investment, the purity of the obtained product exceeds 99%, and the particle size is generally between 30 and 100 nm.

Description

technical field [0001] The invention relates to a preparation method of magnesium hydroxide, in particular to a preparation method of nano-scale magnesium hydroxide. Background technique [0002] Magnesium hydroxide is an additive inorganic flame retardant with triple functions of filling, flame retardant and smoke suppression, and can be used for flame retardant of various polymers. In addition, magnesium hydroxide can also be used in flue gas desulfurization in environmental protection, treatment of lead-containing wastewater and wastewater deammonization and dephosphorization, etc., and in acid rain soil treatment, food and feed additives, oil additives, agricultural magnesium fertilizer, cigarette paper Smoke suppression coatings and biological and pharmaceutical preparations have varying degrees of application, and are recognized as environmentally friendly green chemical products. [0003] There are many ways to prepare magnesium hydroxide, but...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C01F5/22C01F5/14
Inventor 王杰宋锡瑾
Owner ZHEJIANG UNIV