There are mainly the following types of magnesium chloride preparing high -pure magnesium oxide.
1. Precision method
Magnesium chloride solution and alkali or salt (such as NaOH, CAOH, NH3 · H2O, NA2CO3, NH4 (HCO3) 2) Reading generate magnesium hydroxide or alkaline magnesium chloride, and then magnesium oxide.
Mainly lime, ammonia and ammonium carbonate.
1.1 Lime Law
Magnesium chloride solution reacts with lime or calcium hydroxide solution to generate magnesium hydroxide precipitation, and then magnesium oxide is obtained by filtering, washing, drying, and roasting.
Reaction formula:
MGCL2 + CA (OH)2 → Mg (OH)2 ↓ + CACL2
Advantages: simple craftsmanship and low cost.
Disadvantages: The purity of the product is not high, generally 95%~ 98%.
1.2 ammonia method
Magnesium hydroxide precipitation is generated with magnesium chloride solution and ammonia water reactions, and magnesium oxide is obtained by filtering, washing, drying, and roasting.
Reaction formula:
MgCL2 + 2NH3 + 2H2O → Mg (OH)2 ↓ + 2NH4CL
Advantages: The purity of the product is high, generally 99%~ 99.5%.
Disadvantages: complex craftsmanship and high cost.
1.3 ammonium carbide method
Magnesium carbonate to precipitate magnesium carbonate, and then the magnesium oxide is obtained by thermal decomposition.
Reaction formula:
MgCl2 + 2NH4HCO3 → MgCO3 ↓ + 2H4Cl + H2O + CO2 ↑
MgCO3 → MgO + CO2 ↑
Advantages: The purity of the product is high, which can reach more than 99.9%.
Disadvantages: high cost of raw materials and low value of by -production value.
2. Thermal solution method
Concentrate the magnesium chloride solution, and then heat the heat at high temperature to generate magnesium oxide and hydrogen chloride gases.
Reaction formula:
MgCL2 → MgO + HCL ↑
Advantages: Short process and process, easy to achieve automation control.
Disadvantages: The purity of the product is not high, generally 97%~ 99%.
3. Extracting method
Use the extraction agent to extract the magnesium ions in the magnesium chloride solution, and then the magnesium hydroxide was obtained by hydrolysis.
Advantages: The purity of the product is high, which can reach more than 99.9%.
Disadvantages: complex craftsmanship and high cost.
4. Electricity
Magnesium chloride solution electrolyze to generate magnesium oxide and chlorine.
Reaction formula:
MgCl2 → MgO + Cl2↑
Advantages: The purity of the product is high, which can reach more than 99.9%.
Disadvantages: high energy consumption and high cost.
Summarize
The choice of magnesium chloride preparing high -purity magnesium oxide technology should be comprehensively considering factors such as product purity, process cost, and environmental impact. At present, it is widely used in the precipitation method and thermal solution.