Introduction:
The suspension of magnesium hydroxide in water is called magnesium hydroxide emulsion, referred to as magnesium milk. Magnesium hydroxide is a colorless hexagonal column crystal or white powder, hardly soluble in water and alcohol, soluble in dilute acid and ammonium salt. The solution, the aqueous solution is alkaline. The solubility in water is small, and high school students think it is a weak electrolyte. Natural mineral brucite of magnesium hydroxide. Can be used in sugar and magnesium oxide.
Classification
into light and heavy
Index
Item |
Index |
Class I |
Class II
|
Class III
|
First grade |
Qualified product |
First grade |
Qualified product |
Magnesium hydroxide (Mg (OH2)'s mass fraction /% ≥ |
97.5 |
94.0 |
93.0 |
93.0 |
92.0 |
Calcium oxide (CaO)'s mass fraction /% ≤ |
0.10 |
0.05 |
0.1 |
0.5 |
1.0 |
Hydrochloric acid insoluble matter's mass fraction /% ≤ |
0.10 |
0.2 |
0.5 |
2.0 |
2.5 |
Moisture /% ≤ |
0.5 |
2.0 |
2.5 |
2.0 |
2.5 |
Chloride (in terms of Cl)'s mass fraction /% ≤ |
0.10 |
0.4 |
0.5 |
0.4 |
0.5 |
Iron (Fe)'s mass fraction /% ≤ |
0.005 |
0.02 |
0.05 |
0.2 |
0.3 |
Sieve residue's mass fraction (75μm test sieve) /% ≤ |
- |
0.02 |
0.05 |
0.5 |
1.0 |
Laser particle size (Dso) μm |
0.5-1.5 |
- |
- |
- |
- |
Loss on ignition /% ≥ |
30.0 |
- |
- |
- |
- |
Whiteness ≥ |
95 |
- |
- |
- |
- |
Preparation method
1. Brine-lime method The lime milk prepared by the pre-purified and refined brine and the digested and slag-treated lime is precipitated in a sedimentation tank, and a flocculant is added to the obtained slurry, and fully mixed. , enter the settling tank for separation, and then filtered, washed, dried, and pulverized to obtain a finished magnesium hydroxide.
2. Brine-Ammonia method The brine is removed by purification to remove impurities, and ammonia water is used as a precipitant to carry out a precipitation reaction in a reaction vessel. A certain amount of seed crystals are charged before the reaction, and the mixture is thoroughly stirred. The temperature is controlled at 40 °C. After the reaction is completed, a flocculating agent is added, and the precipitate is filtered, washed, dried, and pulverized to obtain a finished magnesium hydroxide.
3. Bitter soil - Hydrochloric acid - Ammonia water magnesite ore and anthracite or coke are calcined in a shaft kiln to form magnesium oxide and carbon dioxide. The bitter soil powder is adjusted to a slurry and then reacted with a predetermined concentration of hydrochloric acid to prepare a magnesium chloride solution. The magnesium chloride solution is reacted with a certain concentration of ammonia water in a reactor, and the product is washed, sedimented, separated by filtration, dried, and pulverized to obtain a magnesium hydroxide product. Surface treatment can be added for surface treatment as needed
Application
1. Magnesium hydroxide is an excellent flame retardant for plastics and rubber products. As a flue gas desulfurizer in environmental protection, it can replace caustic soda and lime as a neutralizing agent for acid-containing wastewater. Magnesium hydroxide flame retardant is colorless, non-toxic, odorless, non-corrosive and other properties, and is a green environmentally friendly polymer material additive.
2. Used in the electronics industry, pharmaceuticals, sugar refining, as insulation materials and in the manufacture of other magnesium salt products.
3. Antacids, osmotic laxatives.
4. As an important chemical product, magnesium hydroxide micro-nano materials have been widely used in ceramics, flame retardant, catalytic, and environmental protection fields.
5. Sewage treatment such as printing and dyeing wastewater.
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