1. Magnesium 
    oxide Magnesium oxide (chemical formula: MgO) is an oxide of magnesium, an ionic compound. It is a white solid at room temperature. Magnesium oxide exists in the form of periclase in nature and is a raw material for magnesium smelting. 
    Magnesium oxide has a high degree of refractory insulation properties. It can be converted into crystal by burning at a temperature above 1000 °C, and it is raised to 1500 - 2000 °C [1] to form a burnt magnesia (also known as magnesia) or sintered magnesia. 
    Magnesium oxide is commonly known as bitter soil, also known as magnesium oxide. Magnesium oxide is an alkaline oxide and has the property of a basic oxide. It is a gelling material. White powder (light yellow is magnesium nitride), odorless, odorless, non-toxic, is a typical alkaline earth metal oxide, chemical formula MgO. A white powder having a melting point of 2852 ° C, a boiling point of 3600 ° C and a relative density of 3.58 (25 ° C). Soluble in acid and ammonium salt solution, insoluble in alcohol. Solubility in water is 0.00062 g/100 mL (0 °C), 0.0086 g/100 mL (30 °C). Exposure to air, easy to absorb water and carbon dioxide and gradually become basic magnesium carbonate, lighter products are faster than heavy products, combined with water to form magnesium hydroxide under certain conditions, slightly alkaline reaction, pH of saturated aqueous solution It is 10.3. Soluble in acid and ammonium salts are insoluble in water, and the solution is alkaline. Do not dissolve in ethanol. Strong refraction in the visible and near-ultraviolet range. Magnesite (MgCO3), dolomite (MgCO3·CaCO3) and seawater are the main raw materials for the production of magnesium oxide. Thermal decomposition of magnesite or dolomite gives magnesia. The seawater is treated with slaked lime to obtain magnesium hydroxide precipitate, and the magnesium hydroxide is burned to obtain magnesium oxide. The magnesium chloride halide block obtained by comprehensive utilization of seawater or the brine after bromine extraction may be used as a raw material, and sodium hydroxide or sodium carbonate may be added to form magnesium hydroxide or basic magnesium carbonate precipitate, and then calcined to obtain magnesium oxide. China mainly uses magnesite, dolomite, brine or halogen blocks as raw materials .

    2. Classification of 
magnesium oxide is divided into light magnesium oxide and heavy magnesium oxide.

    Magnesium oxide (lightweight) CAS: 1309-48-4? GB: HG/T 2573-2012 
Lightweight mainly used as ceramic, loose volume, white amorphous powder. Odorless, tasteless and non-toxic. The density is 3.58 g/cm3. Hard to dissolve in pure water and organic solvents, solubility in water increases due to the presence of carbon dioxide. Soluble in acid, ammonium salt solution. It is converted into crystals by high temperature burning. In the case of carbon dioxide in the air, it forms a double salt of magnesium carbonate. 
Index 
Mgo ≥ 93% 
Fe203 
≤ 0.5% S ≤ 0.03% 
CI ≤ 0.05% Ca ≤ 
0.5% 
activity (iodine absorption value): 90-180 
hydrochloric acid insoluble matter ≤ 0.05% 
particle size range (D50): 2-10 microns

    Preparation: Light magnesium oxide is generally changed from magnesium chloride, magnesium sulfate or magnesium hydrogencarbonate to a water-soluble product and then chemically converted into a water-insoluble product, which is then calcined to magnesium oxide.

    Magnesium oxide (heavy) CAS: 1309-48-4? GB: HG/T2679-2006 
Generally referred to as magnesium oxide is heavy magnesium oxide, alias lamp powder. White or beige powder. It is easy to absorb moisture and carbon dioxide in the exposed air, and it is easy to gel and harden when mixed with magnesium chloride solution. The heavy volume is compact, easy to combine with water, and it is easy to absorb water and carbon dioxide in the exposed air. Easy to gel and harden 
packaging with magnesium chloride solution 50Kg/bag

    Heavy magnesium oxide is divided into light burning and re-burning. The use of magnesite building materials is light burning and heavy burning in heavy magnesium oxide. The 
difference between 
light burning and re-burning is mainly based on the sintering temperature. When the sintering temperature is below 1200 °C, the magnesium oxide produced generally belongs to lightly burned magnesia. When the sintering temperature reaches 1200 degrees or more, the magnesia is called calcined magnesium.

    Preparation: Magnesite, magnesite is directly calcined. 
Application: Heavy light burnt magnesia is used in the rice milling industry for grinding and semi-rolling; the construction industry is used to manufacture artificial chemical flooring, artificial marble, heat-proof panels, sound insulation panels; the plastics industry is used as a filler; Can be used to produce other magnesium salts. The pharmaceutical industry is used to formulate internal medicines to combine excess stomach acid. Used as magnesium fertilizer in agriculture; used in water treatment and desulfurization.

    85 powder magnesium chloride building materials external wall insulation 
90 yellow powder used for water treatment, desulfurization 
90 light white powder used as magnesium fertilizer. 
Heavy light burning powder contains 85 light burning powder, 90 light yellow powder, 90 light white powder, the size is about 200 mesh. 

3. Preparation method (summary) 
Magnesium oxide double reduction carbonization method in 
order to improve the extraction rate of magnesium oxide and reduce the product energy Consumption. To improve product quality and increase product variety, the double-reduction carbonization process mainly changes the carbonization conditions and subtracts the high-energy production process. The purified lime emulsion is subjected to a carbonization reaction under specific conditions to dissolve 80-90% of MgO, and a supersaturated solution of light magnesium carbonate containing 20-30 g/liter of MgO is formed. After rapid pressure filtration, the basic magnesium carbonate is resolved under a specific condition by a saturated solution of light magnesium carbonate at 20-30 degrees. The basic magnesium carbonate filter cake has a moisture content of only 50-60%. Calcined to obtain a light magnesium oxide product. 
The characteristics of the process: (see the process flow chart for details) 
(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 product is reduced by 75%, and the power consumption is reduced by 65%. [3]  
Magnesium oxide gas phase method 
High-purity magnesium metal and oxygen are reacted to form crystal nuclei, and then the particles are further grown to obtain high-purity fine powder magnesia. The crude raw material containing 80% by weight or more of magnesium oxide is dissolved with a mineral acid (sulfuric acid, hydrochloric acid, nitric acid) at a molar ratio of 1:2 to obtain a magnesium salt of a mineral acid. The impurities are removed by purification, subjected to pressure heat treatment in an oxygen atmosphere, washed with water, dehydrated, dried, and heated at 1100 ° C for 1 h to obtain high-purity magnesium oxide.
Magnesium hydroxide calcination method uses magnesium sulfate solution for impurity removal as raw material, and pure ammonia water is used as precipitant to precipitate Mg(OH)2 in magnesium solution, and solid-liquid separation is carried out by plate and frame filter press, and the filter cake is washed high. The purity of Mg(OH)2 is obtained by drying and calcining to obtain high-purity magnesium oxide. 
The calcined bituminous powder is subjected to water selection to remove impurities and precipitated into a magnesium slurry, which is then dehydrated to form magnesium oxide by digestion, drying and calcination. MgO+H2O→Mg(OH)2Mg(OH)2→MgO+H2O; 
magnesia calcination method calcination of 
magnesite in 950°C in a calciner, followed by cooling, sieving and pulverization to obtain light Burning magnesium oxide. 
The soda ash method firstly dilutes the bitter brine with water to about 20 ° Be to be added to the reactor, and slowly adds a soda clarified solution of about 20 ° Be under stirring, and reacts at 55 ° C to form a heavy magnesium carbonate, which is rinsed and centrifuged. The calcination is carried out at 700 to 900 ° C, and the light magnesium oxide product is obtained by pulverization and air separation. 5Na2CO3+5MgCl2+6H2O→4MgCO3·Mg(OH)2·5H2O+10NaCl+CO2↑ 
4MgCO3·Mg(OH)2·5H2O→5MgO+4CO2↑+6H2O 
Magnesium Oxide Carbonization 
Dolomite is calcined, digested and carbonized The basic magnesium carbonate is obtained, and then thermally decomposed, calcined, pulverized, and air-selected to obtain a light magnesium oxide. Its MgCO3·CaCO3→MgO+CaO+2CO2↑ 
(MgO+CaO)+2H2O→Mg(OH)2+Ca(OH)2 
Mg(OH)2+Ca(OH)2+3CO2→Mg(HCO3)2+ CaCO3+H2O5 
Mg(HCO3)2+H2O→4MgCO3·Mg(OH)2·5H2O+6CO2↑4MgCO3·
Mg(OH)2·5H2O→5MgO+4CO2↑+6H2O ammonium bicarbonate method. The mother liquor after seawater salt formation (magnesium ion content is about 50g/L) is removed from impurities and mixed with ammonium hydrogencarbonate in an appropriate ratio to carry out precipitation reaction. Then, by centrifugal dehydration, drying, calcination, pulverization and classification, and packaging, the finished product of light magnesium oxide is obtained. 5MgCl2+10NH4HCO3+H2O→4MgCO3·Mg(OH)2·5H2O+10NH4CI+6CO2↑ 
4MgCO3·Mg(OH)2·5H2O→5MgO+4CO2+6H2O; the 
magnesia carbonation method 
adopts dolomite or magnesite, Activated magnesium oxide can be obtained by calcination, water digestion, carbonation, calcination and pulverization. The brine dolomite lime method uses seawater or brine as a raw material to precipitate with lime or dolomitic ash, and the obtained magnesium hydroxide precipitate is filtered, dried and calcined to obtain active magnesium oxide. The bitter soil-sulfate-carbonic acid method reacts the magnesium-containing raw material such as bitter soil powder with sulfuric acid to form a magnesium sulfate solution, and the MgO+H2SO4→MgSO4+H2O magnesium sulfate solution reacts with ammonium hydrogencarbonate to form magnesium carbonate precipitate, and the MgSO4 is formed. +NH4HCO3+NH3→MgCO3↓+(NH4)2SO4 The precipitate is then separated by filtration, washed, dried, calcined and pulverized to obtain active magnesium oxide. 
The magnesium oxide sintering method 
uses an fused magnesium block as a raw material. After material selection, crushing and sieving, it is thoroughly mixed with a certain proportion of liquid titanium dioxide, and then washed, dried and sintered to select a particle size of 40-150 mesh, which is the finished high-temperature electrical grade magnesium oxide. 
The magnesium oxide brine ammonium carbonate method 
uses a brine to react with ammonium hydrogencarbonate to form a basic magnesium carbonate, which is then aged, washed, dehydrated, dried, calcined, pulverized, then purified, and heat treated to obtain a silicon steel grade magnesium oxide. 
The magnesium oxide electrofusion method 
uses high-purity magnesium oxide as a raw material and is obtained by electrofusion. 
Magnesium oxide hydrochloric acid method
The waste material for producing heavy magnesium oxide is sent to the reactor, and hydrochloric acid is added to carry out a reaction to form magnesium chloride hexahydrate, and then sodium carbonate is added for reaction to form basic magnesium carbonate, which is washed with water, and the basic magnesium carbonate is calcined at a high temperature and cooled. After pulverization, magnetic magnesium oxide is obtained. It is 
used in the 
chemical industry for the production of magnesium sulfate, 2MgO+4HCI+4H2O→2MgCl2·6H2O·5MgCl2+5Na2CO3+6H2O→4MgCO3·Mg(OH)2·5H2O+CO2↑+10NaCl4MgCO3·Mg(OH)2·5H2O Magnesium hydroxide, magnesium chloride and other raw 
materials used in building materials industry, magnesium mobile houses, magnesium fertilizer production raw materials, waste acid water neutralizer, heavy metal ion adsorbent 
industrial oxidase: also known as light magnesium oxide. It plays an important role in many inorganic salt products. 
It is mainly used in the production of enamel, ceramics, refractory materials, etc. 
as a filler 
in the manufacture of polishing agents, adhesives and paints. It is used as a promoter and catalyst 
in rayon, rubber (chloroprene rubber, fluororubber). Antacids and laxatives are used to treat hyperacidity, stomach and duodenal ulcers 
as a decolorizing agent used by food processors as a sugar refining agent. Ice cream powder ph regulators 
in the construction industry, magnesium oxide can produce magnesium-containing special cement and insulation boards, etc.: The 
largest use in agriculture is used as feed for fertilizers and livestock, and is the main element in the metabolism of plants and animals. Used as a feed for dairy cows to prevent nervous system dysfunction caused by magnesium deficiency, the so-called pasture rickets; 
in the chemical industry, the use of magnesium and magnesium chemicals such as magnesium sulfate, magnesium oxide and other industrial products;
In addition, it is also used in water treatment, flue gas cleaning and in the glass, dye, cable, silicon steel industry, uranium processing electronics industry, insulation materials industry, as well as in petroleum additives, casting, phenolic plastics and other industries. .