HIGH-PURITY MAGNESIUM OXIDE AND ITS PRODUCTION METHOD Russian patent published in 2022 - IPC C01F5/08 C01F5/22 

FIELD: chemical technology.

SUBSTANCE: invention relates to a chemical technology for the production of high-purity magnesium oxide used in the pharmaceutical, cosmetic and food industries, in the production of ceramics, glass, optical materials, electronic materials, catalysts, polymer materials, transformer steel. High-purity magnesium oxide has a specific surface determined by the BET method in the range from 5 to 70 m²/g, the average particle size (d50) determined by laser diffraction is no more than 5 microns, the mass fraction of impurities of each of the elements Pb, Cd, As, Hg is no more than 0.1 ppm, the mass fraction of impurities of each of the elements Ba, Zn, Ti, Mn, Co, Mo, V, Sb, Sr no more than 1 ppm, the mass fraction of impurities of each of the elements Al, F no more than 5 ppm, the mass fraction of impurities of each of the elements P, Cr, Ni, K, Li no more than 10 ppm, the mass fraction of Fe no more than 50 ppm, Si mass fraction no more than 0.01%, the mass fraction of impurities of each of the elements Ca, B is no more than 0.02%, the mass fraction of sulfates is no more than 0.02%, the mass fraction of the impurity of the element Na is no more than 0.05%, the mass fraction of the chloride impurity is no more than 0.05%, and includes primary particles and agglomerates consisting of primary particles. High-purity magnesium oxide is obtained by calcining magnesium hydroxide obtained by the interaction of a purified concentrated aqueous solution of magnesium chloride with an aqueous solution of sodium hydroxide in a continuous manner at a temperature of 40-90°C, stirring at a speed of 20-300 rpm, with a molar ratio of ОН^-:Mg⁺⁺ ions in the range of (1,9÷2,1):1 with continuous supply to the reaction mass of a suspension of seed crystals of magnesium hydroxide in the amount of 5-200% of the total mass of the supplied initial reagents, moreover, the seed crystals of magnesium hydroxide are pretreated with a concentrated aqueous solution of magnesium chloride, after the interaction of the reagents, the suspension of magnesium hydroxide is directed to aging at a temperature of 40-90°C, then hydrothermal crystallization of magnesium hydroxide particles is carried out in the presence of diatomic alcohol: ethylene glycol or propylene glycol at a temperature ranging from 120 to 220°C, pressure ranging from 0.1 to 2.3 MPa and duration in the range from 1 to 10 h, the resulting suspension of magnesium hydroxide is filtered, washed, and calcination of magnesium hydroxide is carried out at a temperature of 700-1100°C.

EFFECT: resulting high-purity magnesium oxide has a high chemical purity, adjustable specific surface area, pore volume and pore size distribution, granulometric composition and activity.

19 cl, 2 tbl, 5 ex