Hebei Messi Biology Co., Ltd. stated that light magnesium carbonate is a white amorphous powder, easily soluble in acid, slightly soluble in water, with a density of 2.16g/cm3, poor thermal stability, and begins to decompose at 300°C, and quickly decomposes into magnesium oxide at 800-900°C. Light magnesium carbonate is a high-grade inorganic filler, reinforcing agent and good flame retardant in the rubber and plastic industry, a filler for high-grade inks, pigments, toothpastes and cosmetics, and a raw material for high-grade ceramics, glass and fire-retardant coatings.
Dolomite is fed into a vertical kiln and calcined at 900-1000°C to generate dolomite ash.
Dolomite ash is digested into dolomite ash milk by adding water.
Carbonize the ash milk with appropriate concentration with CO2 gas. At this time, CaCO3 precipitates out due to its low solubility in water. When the CO2 partial pressure is maintained at 2-3 atmospheres, 80-90% Mg(OH)2 can react with CO2 to generate Mg(HCO3)2 and be dissolved to generate a saturated magnesium bicarbonate solution. At this time, filter, Mg++ remains in the solution, and CaCO3 remains in the filter cake, and the separation of Ca++ and Mg++ can be achieved.
The filtrate after the separation of calcium and magnesium ions is a supersaturated solution of Mg(HCO3)2, called heavy magnesium water. At this time, the content of magnesium oxide in each liter of solution is only 20-30g, so magnesium must be enriched. Due to the poor thermal stability of Mg(HCO3)2, the solution can be heated to decompose the heavy magnesium water.
Generate basic magnesium carbonate precipitation. Then filter, dry, and disperse the precipitate to obtain the finished product. At this time, the filtrate contains a part of Mg++ that needs to be recovered. This filtrate can be recovered to digest the dolomite, and Mg++ can be recycled.
The main factors affecting the quality of light magnesium carbonate products are: dolomite quality, calcination process and equipment, digestion process and impurity removal rate, carbonization process, Mg++ enrichment and separation process from Ca++ and drying and dehydration process. The requirements for raw material quality in the production of light magnesium carbonate are: CaO>54%, MgO>18.0%, SiO2<1.0%, Al2O3+ Fe2O3<1.0%.