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Technique for preparing high purity ultra-fine magnesium hydroxide by sodium hydroxide method

A technology of ultra-fine magnesium hydroxide and sodium hydroxide, applied in the direction of magnesium hydroxide, etc., can solve problems such as difficulty in washing

Inactive Publication Date: 2008-08-06
GUIZHOU UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The present invention explores the technological conditions of producing high-purity ultra-fine magnesium hydroxide by the decomposition method of industrial sodium hydroxide crystal seeds through experimental research, and studies the influence of multiple factors affecting the cyclic decomposition of seed crystals on the recovery rate of magnesium hydroxide and the performance of filtration and washing. Determined the better production process conditions of sodium hydroxide seed crystal decomposition method, while ensuring high magnesium conversion rate, solved the problem of difficult filtration and washing of magnesium hydroxide filter cake produced by sodium hydroxide method

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  • Technique for preparing high purity ultra-fine magnesium hydroxide by sodium hydroxide method
  • Technique for preparing high purity ultra-fine magnesium hydroxide by sodium hydroxide method
  • Technique for preparing high purity ultra-fine magnesium hydroxide by sodium hydroxide method

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Experimental program
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Effect test

Embodiment 1

[0134] The process of producing high-purity ultra-fine magnesium hydroxide by sodium hydroxide dry crystal seed decomposition method is as follows: Mg 2+ Purified brine with a concentration of 20g / L and solid magnesium hydroxide seed crystals are added to the reaction tank and mixed, and kept at a certain temperature (60-80°C), the seed crystal coefficient is 1.0, and then sodium hydroxide solution (350g / l) is added to the reaction tank Precipitation reaction was carried out in the medium, the alkali excess coefficient was 1.05, crystallization and aging at a temperature of 70°C for 90 minutes, after the reaction was completed, the magnesium hydroxide slurry was extracted and filtered, and washed several times (liquid-solid ratio L / S=8, washing temperature 40°C, Washing time is 10 minutes), the filtered slurry stock solution is used to evaporate and extract chemically pure sodium chloride; the washing liquid is returned to the process for batching or system replenishment. The ...

Embodiment 2

[0136] The process of producing high-purity ultra-fine magnesium hydroxide by sodium hydroxide wet seed circular decomposition method is as follows: Mg 2+ The purified brine with a concentration of 30g / L and the magnesium hydroxide slurry obtained from the previous reaction are mixed in the reaction tank, kept at a certain temperature (60-80°C), and the seed crystal coefficient is 0.5, and then the sodium hydroxide solution (300g / l) Put it into the reaction tank for precipitation reaction, the alkali excess coefficient is 1.01, crystallize and age at 55°C for 120 minutes, after the reaction is completed, take part of the magnesium hydroxide slurry for filtration and continuous washing, and the filtered slurry stock solution is used for evaporation and extraction of chemical Pure sodium chloride; the washing liquid is used for batching or system water replenishment in the return process; the final eluent can be directly discharged or returned to the system as water replenishment...

Embodiment 3

[0138] The process of producing high-purity ultra-fine magnesium hydroxide by sodium hydroxide wet seed circular decomposition method is as follows: Mg 2+ The purified brine with a concentration of 25g / L and the magnesium hydroxide slurry obtained from the previous reaction are mixed in the reaction tank, kept at a certain temperature (60-80°C), and the seed crystal coefficient is 1.5, and then the sodium hydroxide solution (320g / l) Add it into the reaction tank for precipitation reaction, the alkali excess coefficient is 1.03, and crystallize and age at 90°C for 30 minutes. After the reaction, take part of the magnesium hydroxide slurry for filtration, continuous vacuum filtration and rinsing, and use the filtered slurry stock solution It is used to extract chemically pure sodium chloride by evaporation; it is used for batching or system replenishment in the washing liquid return process; finally, the eluent can be directly discharged or returned to the system as replenishing ...

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Abstract

The invention discloses a process for preparing high-purity ultrafine magnesium hydroxide by a sodium hydroxide method; by using a crystal seed decomposition method, purified brine and crystal seed of the magnesium hydroxide are added to a reaction pool to be mixed and temperature is kept at 60-80 DEG C; then solution of the sodium hydroxide is added to the reaction pool to carry out the precipitation reaction, crystallization and aging; after the reaction is finished, slurry of the magnesium hydroxide is filtered and washed; cake after filter is dried and crashed, the crystal product of the magnesium hydroxide is obtained. Compared with the prior art, the process for preparing the high-purity ultrafine magnesium hydroxide accelerates agglomeration and growth of the magnesium hydroxide crystal by adding the crystal seed, solves the problem of the difficulty for filtering and washing the filter cake by using the prior sodium hydroxide method to produce the magnesium hydroxide, and directly utilizes the slurry of the magnesium hydroxide generated by the reaction as the crystal seed to carry out cyclic decomposition. The process flow is simple and the process parameter can be easily controlled. The production process is pro-environment without producing pollutant. At the same time, the purity of the magnesium hydroxide obtained by the process and the recovery rate of the magnesium are very high; furthermore, the purity of the by-product sodium chloride is high. The process for producing the magnesium hydroxide has great development prospect.

Description

Technical field: [0001] The invention relates to a process for preparing high-purity ultrafine magnesium hydroxide by a sodium hydroxide method, and belongs to the technical field of preparation of magnesium hydroxide products. Background technique: [0002] Magnesium hydroxide, as a halogen-free, inorganic additive flame retardant, is currently a good variety of inorganic additive flame retardants in terms of comprehensive functions and technical and economic evaluations, so it has attracted widespread attention from all over the world. Making full use of various magnesium-containing raw materials to accelerate the development of magnesium hydroxide and meet the needs of domestic and foreign markets is one of the important development directions of the current magnesium chemical industry. [0003] At present, titanium smelting is mainly produced by magnesia thermal reduction method, and the main reactions are as follows: [0004] TiO 2 +2Cl 2 +C=TiCl 4 +CO 2 [0005] ...

Claims

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Application Information

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IPC IPC(8): C01F5/14
Inventor 李军旗郭晓光毛小浩袁继维赵平原唐道文金会心吴复忠
Owner GUIZHOU UNIV
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