The production process of food grade magnesium oxide has the following main types:
1. Brine ammonium carbonate preparation method
Take high magnesium brine as raw material and adopt ammonium bicarbonate method to produce magnesium oxide. The specific process flow is as follows:
Brine pretreatment: the high magnesium brine is precipitated, filtered and washed to remove impurities.
Evaporation and concentration: the pretreated brine is evaporated and concentrated to get high magnesium concentrate.
Ammonium carbonate precipitation: add high magnesium concentrate into ammonium bicarbonate solution, carry out the precipitation reaction, generate magnesium hydroxide.
Filtering and washing: the precipitated magnesium hydroxide is filtered and washed to remove impurities.
Calcination: Calcine the washed magnesium hydroxide at high temperature to produce magnesium oxide.
Crushing: the calcined magnesium oxide is crushed to get food grade magnesium oxide finished product.
2. Dolomite secondary carbonization method
Take dolomite as raw material, prepare magnesium oxide by secondary carbonization method. The specific process is as follows:
Calcination: Calcine dolomite at high temperature to generate magnesium oxide and calcium oxide.
Water digestion: the calcined magnesium oxide and calcium oxide are digested with water to generate magnesium hydroxide and calcium hydroxide.
Subcarbonation: pass carbon dioxide into the solution of magnesium hydroxide and calcium hydroxide to produce magnesium carbonate and calcium carbonate.
Filtering and washing: the magnesium carbonate is filtered and washed to remove impurities.
Calcination: the washed magnesium carbonate is calcined at high temperature to produce magnesium oxide.
Crushing: the calcined magnesium oxide is crushed to get food grade magnesium oxide finished product.
3. Seawater extraction method
Take seawater as raw material, adopt seawater extraction method to prepare magnesium oxide. The specific process flow is as follows:
Seawater pretreatment: the seawater will be precipitated, filtered, ion exchange and other processes to remove impurities.
Concentration: the seawater after pretreatment is concentrated to get high magnesium concentrate.
Precipitation: add sodium hydroxide or ammonium bicarbonate solution to the high magnesium concentrate to carry out the precipitation reaction and generate magnesium hydroxide.
Filtering and washing: the precipitated magnesium hydroxide is filtered and washed to remove impurities.
Calcination: Calcine the washed magnesium hydroxide at high temperature to produce magnesium oxide.
Crushing: the calcined magnesium oxide is crushed to get the finished product of food grade magnesium oxide.
Food grade magnesium oxide has strict requirements for quality indicators, so in the production process need to strictly control the process conditions, to ensure product quality in line with national standards.