Method for preparing magnesium hydroxide and chlorine by coupling magnesium chloride reactive crystallization and electrolysis

A technology of reaction crystallization and magnesium hydroxide, which is applied in the direction of magnesium hydroxide, electrolytic process, electrolytic components, etc., can solve the problems of difficult filtration and low purity of magnesium hydroxide, and achieve easy filtration, solution of chlor-alkali balance, and simple process flow Effect

Inactive Publication Date: 2014-03-12
EAST CHINA UNIV OF SCI & TECH
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  • Abstract
  • Description
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Problems solved by technology

[0011] The object of the present invention is to overcome the deficiencies in the prior art, provide a kind of reaction crystallization of magnesium chloride-electrolytic coupling to prepare magnesium hydroxide and chlorine gas method, make up for the low purity of magnesium hydroxide prepare

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  • Method for preparing magnesium hydroxide and chlorine by coupling magnesium chloride reactive crystallization and electrolysis

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Embodiment 1

[0039] First, prepare 2.5mol / l magnesium chloride magnesium-based solution, 5.0mol / l sodium hydroxide lye, 0.5mol / l rubidium chloride solution, and preheat to 60°C for use. Take 90ml rubidium chloride and add it to the reactor as the bottom material. At 60°C and the stirring rate of 1.5m / s, add the lye and the magnesium-based solution to the reactor at the feed rate of 1ml / min at the same time. The reaction is over After suction filtration. The filter cake was washed three times with deionized water, and finally dried in hot air at 120°C for 8 hours. After the filtrate was simply refined by chelating resin, a certain amount of sodium chloride was added to adjust the concentration, at a voltage of 3.2 to 3.7 volts, 94%~ At a current efficiency of 99%, sodium hydroxide and chlorine are prepared by electrolysis using a thin film method. The prepared high purity magnesium hydroxide has a purity of 99.8%, an average particle size of 11.84 μm, and a water content of the filter cake ...

Embodiment 2

[0041] Prepare 3.0 mol / l magnesium chloride aqueous solution (magnesium-based solution), 6.0 mol / l sodium hydroxide aqueous solution (lye), 1.0 mol / l potassium chloride aqueous solution, and preheat to 80°C for use. Take 90ml of potassium chloride aqueous solution and add it to the reactor as the bottom material. At 80°C and at a stirring rate of 1.5m / s, add the lye and magnesium-based solution to the reactor at a feed rate of 1.5ml / min. After the reaction, suction filtration is performed. The filter cake was stirred and washed with deionized water for three times, and finally dried in hot air at 120°C for 8 hours. After the filtrate was simply refined by chelating resin, a certain amount of sodium chloride was added to adjust the concentration, at a voltage of 3.4 to 3.7 volts. Under the current efficiency of %~99%, the membrane method is used for electrolysis to prepare sodium hydroxide and chlorine. The prepared high purity magnesium hydroxide has a purity of 99.7%, an aver...

Embodiment 3

[0043] Prepare 4.0 mol / l magnesium chloride aqueous solution (magnesium-based solution), 8.0 mol / l sodium hydroxide aqueous solution (lye) and 4.0 mol / l sodium chloride aqueous solution, and preheat to 70°C for use. Take 50ml of sodium chloride aqueous solution and add it to the reactor as the bottom material. At 70℃, the stirring rate is 1.2m / s, the lye and magnesium-based solution are added in continuous operation, and the material is continuously discharged. The residence time is 50min. After the system is stable, collect and filter the material liquid. The filter cake was stirred and washed with deionized water for three times, and finally dried at 120°C in hot air for 8 hours. After simple purification, a certain amount of sodium chloride was added to adjust the concentration of the filtrate. At a voltage of 3.4 to 3.7 volts, 94% to 99% Under current efficiency, the membrane method is used for electrolysis to prepare sodium hydroxide and chlorine. The prepared high-purity...

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Abstract

The invention relates to a method for preparing magnesium hydroxide and chlorine by coupling magnesium chloride reactive crystallization and electrolysis. A magnesium hydroxide product is obtained by firstly adopting bischofite and sodium hydroxide as raw materials, adding a chloride as an additive and controlling crystallization. The purity of the magnesium hydroxide product is more than 99.5%, and the magnesium hydroxide product is uniform in grain size distribution and has better dispersibility. Sodium hydroxide and chlorine are prepared by electrolyzing the byproduct sodium chloride in the process. Sodium hydroxide is used as a raw material for reactive crystallization. Magnesium hydroxide and chlorine can be sold as products. Compared with the prior art, the method has the positive effects that the adding of the chloride as the additive is beneficial to improving the crystallization property and dispersing property of magnesium hydroxide, thus solving the problems that magnesium hydroxide filter cakes produced by original sodium hydroxide methods are difficult to filter and wash and have low purity; meanwhile, the process achieves comprehensive utilization of resources and promotes circular economic development; the method is simple in process flow and convenient to operate and easily achieves large-scale industrial production.

Description

【Technical Field】 [0001] The invention relates to the technical field of inorganic salt processing, in particular to a method for preparing magnesium hydroxide and chlorine gas by magnesium chloride reaction crystallization-electrolysis coupling. 【Background technique】 [0002] There are many magnesium resources in salt lakes in my country. The 33 salt lakes in the Qaidam Basin in Qinghai contain 4.15 billion tons of magnesium salt, especially the Chaerhan Salt Lake. The geological survey report shows that the reserves of potassium chloride and magnesium chloride in the lake are 1.45 and 4.0 billion respectively. Tons, the reserves of magnesium chloride are second only to the Dead Sea, ranking second in the world, accounting for more than 87% of the country’s reserves of magnesium salts. The development of salt lake resources is currently focused on extracting potassium, which has reached 3 million tons. After potassium chloride is extracted from the salt lake, the discharged brin...

Claims

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Application Information

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IPC IPC(8): C01F5/22C25B1/34
Inventor 宋兴福于建国孙淑英孙泽孙玉柱许妍霞汪瑾
Owner EAST CHINA UNIV OF SCI & TECH
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