1. Double reduction carbonization method
In order to improve the extraction rate of magnesium oxide and reduce the energy consumption of the product. To improve the quality of products and increase the variety of products, the double subtraction carbonization process mainly changes the carbonization conditions and subtracts the high energy consumption production process. The purified lime emulsion was carbonized under specific conditions so that 80-90% MgO was dissolved and a supersaturated solution of light magnesium carbonate containing 20 ~ 30g / L MgO was formed. Basic magnesium carbonate was obtained from the saturated solution of 20 ~ 30 ℃ light magnesium carbonate by rapid pressure filtration under certain conditions. This basic magnesium carbonate filter cake contains only 50-60% moisture. Calcined light magnesium oxide products.
The functionalities of the process:
(1) the extraction rate of magnesium oxide 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%.
As a result, the coal consumption per ton of light magnesium oxide products is reduced by 75%, and the electricity consumption is reduced by 65%.
2. Gas phase method
The crystal nucleus was formed by the reaction of high purity magnesium with oxygen, and then the particles continued to grow to produce high purity fine powdered magnesium oxide. Raw materials of dross containing more than 80% (weight) of magnesium oxide are dissolved with inorganic acid (sulfuric acid, hydrochloric acid, nitric acid) in the molar ratio of 1: 2 to prepare the magnesium salt of an inorganic acid. After purification and removal of impurities, impurities were heated under pressure in an oxygen atmosphere, then washed, dehydrated, dried and heated at 1100 ° C for 1 hour, high purity magnesium oxide was prepared.
Magnesium hydroxide calcination method: Mg (OH) 2 is precipitated by adding pure ammonia in magnesium solution after removing impurities and purifying as raw material. After solid-liquid separation by plate and frame filter press, the filter cake is washed to obtain high purity Mg (OH) 2, then the high purity magnesium oxide is prepared by drying and calcination.
Calcination method Bitter soil powder by separating water, removing impurities and precipitating in suspension of magnesium, then by digestion, drying, calcination, dehydration of magnesium hydroxide to produce magnesium oxide:
MgO + H2O → Mg (OH) 2
Mg (OH) 2 → MgO + H2O
3. Method of calcination
The magnesite was calcined at 950 in a calcination furnace, then cooled, sieved and crushed to produce lightly burnt magnesium oxide.
In the soda method, the brine was diluted with water at about 20 ° Be and added to the reactor. The sodium hydroxide clarifying solution of about 20 ° Be was added slowly with stirring, and the reaction was carried out at about 55 ° C to generate heavy magnesium carbonate. After rinsing and centrifugal separation, the heavy magnesium carbonate was roasted at 700 ~ 900 ℃, and the light magnesium oxide products were obtained by grinding and air separation.
5Na2CO3 + 5MgCl2 + 6H2O → 4MgCO3 Mg (OH) 2 5H2O + 10NaCl + CO2 ↑
4MgCO3 Mg (OH) 2 5H2O → 5MgO + 4CO2 ↑ + 6H2O
4. The carbonization method
After calcination, digestion and carbonization of dolomite, basic magnesium carbonate can be obtained, then light magnesium oxide can be obtained by thermal decomposition, calcination, grinding and wind separation.
5. Manufacturing method
The ammonium bicarbonate method is used to remove impurities and mix with ammonium bicarbonate in an appropriate proportion to perform precipitation reactions. After centrifugal dehydration, drying, calcination, classification by crushing and conditioning, one can obtain finished products of light magnesium oxide:
5MgCl2 + 10NH4HCO3 + H2O → 4MgCO3 Mg (OH) 2 5H2O + 10NH4CI + 6CO2 ↑
4MgCO3 Mg (OH) 2 5H2O → 5MgO + 4CO2 + 6H2O
Activated magnesium oxide can be prepared from dolomite or magnesite by calcination, water digestion, carbonation, calcination and grinding. White cloud lime brine method uses sea water or brine as raw material to precipitate with lime or white cloud ash, then dry filter and calcine the precipitate of magnesium hydroxide obtained to produce active magnesium oxide. The best method of soil powder – sulfuric acid – ammonium bicarbonate reacts with raw materials containing magnesium such as bitter soil powder and sulfuric acid to produce magnesium sulfate solution, and sodium sulfate solution. magnesium MgO + H2SO4 → MgSO4 + H2O reacts with ammonium bicarbonate to produce precipitated magnesium carbonate. Its MgSO4 + NH4HCO3 + NH3 → MgCO3 ↓ + (NH4) 2SO4 then the precipitate is filtered and separated, washed, dried, calcined and ground to produce active magnesium oxide.
Use of a block of electrofused magnesium as a raw material. After material selection, crushing and screening, it is fully mixed with a certain proportion of liquid titanium dioxide, then washed, dried and sintered. Particle size from 40 to 150 is filtered, which is the finished high temperature electrical grade magnesium oxide.
8. Ammonium bicarbonate brine method
Using the reaction of brine and ammonium bicarbonate to produce basic magnesium carbonate, then aging, washing, dewatering, drying, calcining, after grinding, purification, heat treatment, silicon steel grade magnesium oxide.
9. The merged method
Using high purity magnesium oxide as a raw material, magnesium oxide was prepared by electric melting.
10. Hydrochloric acid method
The waste from the production of heavy magnesium oxide is sent to the reactor, and hydrochloric acid is added for reaction to generate magnesium chloride hexahydrate, then sodium carbonate is added for reaction to generate carbonate basic magnesium. Basic magnesium carbonate is washed with water, calcined at high temperature, cooled and ground to produce magnetic magnesium oxide.
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