Process for preparing flame retardant grade magnesium hydroxide by ammonia method

Abstract

The invention discloses a process for preparing flame retardant grade magnesium hydroxide by an ammonia method. The process comprises the following steps of: adding purified brine of which the Mg<2+> concentration is 40g / L and ammonia water into a reaction kettle and reacting for 60 minutes at 40 DEG C, wherein the ammonia excessive coefficient is 2.5; filtering and washing reaction slurry; and then drying and pulverizing to obtain a fibroid magnesium hydroxide crystal product. Compared with the prior art, through testing and researching, the process determines an optimal technological condition for producing the magnesium hydroxide by an ammonia method, effectively improves the conversion rate of magnesium, improves the filtering property of a filter cake through adding pure magnesium hydroxide as a seed crystal and solves the problem of difficult filtering because the filter cake changes along with the washing pH; the obtained magnesium hydroxide product conforms to the standard of the HG / T3607-2000 I grade of the flame retardant grade magnesium hydroxide, and indicated through TEM (Transverse Electric and Magnetic Field) morphology analysis, the product is fibroid crystal; and the magnesium hydroxide of the fibroid crystal has good dispersity and flowability.

Description

technical field [0001] The invention relates to a process for preparing flame-retardant grade magnesium hydroxide by an ammonia 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] TiO 2 +2C...

AI Technical Summary

Problems solved by technology

The present invention studies the influence of multiple factors on the recovery rate and filtration performance of magnesium hydroxide produced by the ammonia method through experiments, determines the ideal production process conditions of the ammonia method, and solves the problem of the filter cake changing with the washing pH while effectively improving the magnesium conversion rate. Difficult problems with change filtering

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