Hebei Messi Biology Co., Ltd. stated that magnesium carbonate is an important inorganic chemical material with good filling, dispersibility and flame retardancy. Adding it to engineering plastics can significantly improve the flame retardancy of engineering plastics. At the same time, it can also be used as refractory materials, insulation materials for boilers and pipelines, and for the manufacture of magnesium salt, magnesium oxide, ink, glass, toothpaste, etc. At present, the so-called magnesium carbonate products for short on the market are mostly hydrated basic magnesium carbonate except natural magnesite magnesium carbonate. In the existing production process of hydrated basic magnesium carbonate at home and abroad, the preparation of single-phase anhydrous magnesium carbonate has always been a challenge for chemists, and there are very few patented technologies that can prepare single-phase anhydrous magnesium carbonate .
① adopt soluble magnesium salt (as magnesium chloride, magnesium sulfate, magnesium nitrate or magnesium acetate) and soluble carbonate (as sodium carbonate, potassium carbonate or ammonium carbonate) as precipitation agent, prepare anhydrous magnesium carbonate in solvothermal system, its As the solvent, absolute ethanol, ethylenediamine, etc. are used.
② Using magnesium chloride and urea to synthesize single-phase magnesium carbonate in a hydrothermal system.
③React magnesium chloride hexahydrate, ammonia, and carbon dioxide in a certain ratio at normal pressure and room temperature to obtain magnesium ammonium carbonate tetrahydrate double salt precipitation, and then pyrolyze magnesium ammonium carbonate tetrahydrate at 80-390°C to obtain anhydrous magnesium carbonate and carbon dioxide and ammonia cycle process.
④ Magnesium chloride, ammonium carbonate and ammonium bicarbonate are used as precipitating agents, and sodium hydroxide is used to assist hydrothermal reaction to prepare single-phase anhydrous magnesium carbonate.
Among the above-mentioned preparation methods, most of them adopt hydrothermal or solvothermal preparation methods. The principle is to use some ammonium salts that can form carbonate as a precipitant or to use organic substances such as absolute ethanol as solvents. The production of ammonium chloride and ammonia pollutes the environment, and the cost is relatively high.
The invention provides a method for producing anhydrous magnesium carbonate by carbonization and anhydrous magnesium carbonate, comprising the following steps: preparing a reaction slurry with magnesium hydroxide and deionized water; injecting the reaction slurry into a carbonization tower, and feeding the reaction slurry to the carbonization tower A phase transfer catalyst is added to dissolve the salt solution of metal chloride, and then carbon dioxide is introduced to carry out the carbonization reaction. After the carbonization reaction is completed, anhydrous magnesium carbonate slurry is obtained; the anhydrous magnesium carbonate slurry is filtered to obtain anhydrous magnesium carbonate solid filter Cake and filtrate; Anhydrous magnesium carbonate solid filter cake is dried to obtain anhydrous magnesium carbonate. The product prepared by the invention is single-phase anhydrous magnesium carbonate, has wide application fields, low production process cost and is environmentally friendly.