Preparation of magnesium oxide from solid ore

① Calcined magnesite method

The light burnt magnesium obtained by calcination of magnesite is used as the raw material, and the magnesium bicarbonate solution is prepared by digestion, carbonation, and filtration.
Accurately weigh the treated activated carbon and activator into 1500mL magnesium bicarbonate solution, and then place it in the magnesium bicarbonate solution.
The adsorption and removal reaction is carried out in a thermostatic magnetic stirrer
.

The magnesium bicarbonate solution after adsorption and impurity removal is pyrolyzed at 100°C, the basic magnesium carbonate obtained by the pyrolysis is filtered, washed, dried, and then calcined at 950°C for 3 hours to obtain a high-purity magnesium oxide product

②The carbonization reaction equation of the carbonization method is as follows:

The process flow of carbonization method for producing light magnesium oxide is shown in Figure 4-11
.

In this process, the drying and calcination of basic magnesium carbonate are carried out in a tunnel kiln at the same time

Figure 4-11 Process flow of producing light magnesium oxide by carbonization method

a.

Improved method one: A new process for producing light magnesium oxide using spinning flash drying and spinning dynamic calcination equipment.
The process is shown in Figure 4-12

Figure 4-12 The process flow of producing light magnesium oxide by flash drying and dynamic calcination

b.

Improvement method two: the second carbonization method, the principle is the same as the carbonization method, but the second carbonization and impurity removal are carried out on the basis of it, which relatively improves the purity of the product

Figure 4-13 Process flow of secondary carbonization method

c.

Improvement method three: pressurized carbonization method

d.
Improvement method 4: Carbon-ammonia double cycle method
.

Compared with the traditional carbonization method, this method has a short production cycle, low energy consumption, low production cost and stable product quality.

③Acid hydrolysis method The acid hydrolysis method is mainly divided into six steps: acid hydrolysis, calcination, calcium separation, acid solution, magnesium precipitation, and sintering.
The process flow is shown in Figure 4-14
.

Figure 4-14 Acid hydrolysis process flow

This method produces magnesium oxide with simple raw materials, low equipment investment, low energy consumption, and no industrial waste pollution, but more impurity ions enter.

If multi-step post-processing is not performed, the purity of the product will be affected

④The magnesite crushed by the ammonium sulfate method will react with ammonium sulfate , and the generated magnesium sulfate absorbs ammonia and precipitates, and is calcined to obtain the product magnesium oxide
.
The main reaction formula is:

MgO+(NH ₄ ) ₂ SO ₄ →MgSO ₄ +2NH ₃ ↑+H ₂ O

⑤ Magnesium nitrate method uses magnesium nitrate as oxidant and urea as fuel, and adopts self-propagating combustion method to prepare magnesium oxide nano-powder with a particle size of 15-60 nm
.
The reaction equation is:

Mg(NO ₄ ) ₂ ·6H ₂ O+NH ₂ CONH ₂ →MgO+8H ₂ O+CO ₂ +2N ₂ +O ₂

Related link: Magnesium oxide made from brine