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Magnesium oxide production method

wallpapers Industry 2021-04-02
Double carbon reduction method
In order to improve the extraction rate of magnesium oxide and reduce the energy consumption of the product. To improve product quality and increase product varieties, the double subtractive carbonization process mainly changes the carbonization conditions and subtracts the high energy consumption production process. The purified lime emulsion is subjected to a carbonization reaction under specific conditions so that 80-90% of MgO is dissolved, and a supersaturated solution of light magnesium carbonate containing 20-30 g/L of MgO is generated. After rapid pressure filtration, under specific conditions, the saturated solution of light magnesium carbonate is resolved into basic magnesium carbonate at 20-30 degrees. This basic magnesium carbonate filter cake has only 50-60% moisture. After calcining, a light magnesium oxide product is obtained.
Features of the process:
(1) The extraction rate of magnesium oxide is increased by 20-30%.
(2) The compression and pyrolysis process is subtracted, and the moisture content of the basic magnesium carbonate filter cake is reduced by 25-30%. Therefore, the coal consumption per ton of light magnesium oxide products is reduced by 75%, and the electricity consumption is reduced by 65%.
 
Gas-phase method
The high-purity metal magnesium and oxygen are reacted to form crystal nuclei, and then the particles are continued to grow to obtain high-purity micro-powder magnesium oxide. Crude raw materials containing more than 80% by weight of magnesium oxide are dissolved in mineral acids (sulfuric acid, hydrochloric acid, nitric acid) at a molar ratio of 1:2 to prepare magnesium salts of inorganic acids. Refining to remove impurities, pressurizing and heating treatment in an oxygen atmosphere, and then washing, dehydrating, drying, heating at 1100°C for 1 hour to obtain high-purity magnesium oxide.
 
Magnesium hydroxide calcination method
Using the purified magnesium sulfate solution as the raw material, pure ammonia water is used as the precipitant and added to the magnesium solution to precipitate Mg(OH)2. The plate and frame filter press are used for solid-liquid separation, and the filter cake is washed to obtain high-purity Mg(OH). 2. After drying and calcining, high-purity magnesium oxide is obtained.
The calcined clay powder is water-selected to remove impurities and then precipitates into a magnesium slurry, and then through digestion, drying, and calcination, the magnesium hydroxide is dehydrated to produce magnesium oxide:
MgO+H2O→Mg(OH)2
Mg(OH)2→MgO+H2O
 
Calcination method
The magnesite is calcined in a calciner at 950°C and then cooled, sieved, and pulverized to obtain light calcined magnesia.
In the soda ash method, the bittern is diluted with water to about 20°Be and added to the reactor. Under stirring, a clear solution of soda ash of about 20°Be is slowly added, and the reaction is carried out at about 55°C to produce heavy magnesium carbonate. After rinsing and centrifugal separation, After roasting at 700~900℃, pulverizing and winnowing, the light magnesium oxide product is prepared:
5Na2CO3+5MgCl2+6H2O→4MgCO3·Mg(OH)2·5H2O+10NaCl+CO2↑
4MgCO3·Mg(OH)2·5H2O→5MgO+4CO2↑+6H2O
 
Carbonization
Dolomite is calcined, digested, and carbonized to obtain basic magnesium carbonate, and then thermally decomposed, calcined, crushed, and air-selected to obtain light magnesium oxide.
 
Ammonium Carbonate Method
In the ammonium bicarbonate method, the mother liquor (magnesium ion content of about 50g/L) after salt production from seawater is removed from impurities and mixed with ammonium bicarbonate in an appropriate ratio to undergo precipitation reaction, and then undergo centrifugal dehydration, drying, calcination, crushing and classification. Packing to get the finished product of light magnesia:
5MgCl2+10NH4HCO3+H2O→4MgCO3·Mg(OH)2·5H2O+10NH4CI+6CO2↑
4MgCO3·Mg(OH)2·5H2O→5MgO+4CO2+6H2O
 
Carbonation
Using dolomite or magnesite, calcination, water digestion, carbonation, calcination, and pulverization can be used to prepare active magnesia. The brine dolomite lime method uses seawater or brine as raw materials to react with lime or dolomite ash, and the obtained magnesium hydroxide precipitate is filtered, dried, and calcined to obtain active magnesium oxide. The bitter soil powder-sulfuric acid-ammonium bicarbonate method reacts with the bitter soil powder and other magnesium-containing raw materials with sulfuric acid to form a magnesium sulfate solution. Its MgO+H2SO4→MgSO4+H2O magnesium sulfate solution reacts with ammonium bicarbonate to produce magnesium carbonate precipitation, which is MgSO4 +NH4HCO3+NH3→MgCO3↓+(NH4)2SO4, and the precipitate is separated by filtration, washed, dried, calcined, and crushed to obtain active magnesium oxide.
 
Sintering method
Use fused magnesium block as raw material. After material selection, crushing, and screening, it is fully mixed with a certain proportion of liquid titanium dioxide, then washed with water, dried, and sintered, and the particle size is 40-150, which is the finished high-temperature electrical grade magnesium oxide.
 
Brine bicarbonate method
The brine is reacted with ammonium bicarbonate to generate basic magnesium carbonate, which is then aged, washed, dehydrated, dried, calcined, purified, and heat-treated after crushing to obtain silicon steel grade magnesium oxide.
 
Electrofusion
Using high-purity magnesium oxide as raw material, the finished product is obtained by electrofusion.
 
Hydrochloric acid method
The leftovers from the production of heavy magnesium oxide are sent to the reactor, and hydrochloric acid is added to react to generate magnesium chloride hexahydrate, and sodium carbonate is added to react to generate basic magnesium carbonate, which is washed with water, and the basic magnesium carbonate is calcined at high temperature and cooled. After pulverization, magnetic magnesium oxide is obtained.
 

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