At present, the primary carbonization method or the pressurized secondary carbonization method is generally used to prepare basic magnesium carbonate from dolomite as raw material at home and abroad. Due to different preparation processes, the quality of the products is also different. The prepared products are usually irregular flakes or spherical aggregates. Due to the low production cost and easy control of the dolomite carbonization method, this method is currently commonly used in China to produce light magnesium carbonate.
Hebei Messi Biology Co., Ltd. stated that it uses dolomite as raw material and uses a two-stage secondary carbonization process that combines spray and cap tower to produce a new product of light magnesium carbonate and co-production of ultra-fine magnesium-containing calcium carbonate. This process is fully utilized Dolomite resources have been obtained, with good environmental benefits and significant economic benefits.
The production process is to crush the dolomite ore and calcine it at about 1000°C. The clinker obtained after calcination is sent to the digester to be digested into a certain mass fraction of ash emulsion. After separation and slag removal, the ash emulsion is sent to the carbonization tower and mixed with it from The carbon dioxide in the cleaned and pressurized kiln gas of the calcining kiln undergoes a carbonization reaction. The carbonized liquid that has passed the carbonization process is separated and filtered to obtain filter residue (containing magnesium calcium carbonate, which can be sold as a by-product after drying) and heavy magnesium aqueous solution. Use steam to directly heat to 95~C-103~C to decompose it into basic magnesium carbonate precipitate. The precipitate is separated and dehydrated and dried at 160~230~C, and then crushed and classified to obtain light magnesium carbonate. product.
Under normal pressure, the reaction mechanism of basic magnesium carbonate was prepared by secondary carbonization method using light-burned dolomite powder as raw material, and the optimal process conditions were determined. The results show that the pH value stop point of the first and second carbonization is pH: 10, pH: = 9, and the CO2 partial pressure of the first and second carbonization is P(CO)=0.03MPa, P2(CO2)=0.1MPa, and the carbonization liquid Under the conditions of a concentration of 25L and a stirring speed of 400r/min, a rod-shaped basic magnesium carbonate with a length of about 601xm and a cross-sectional diameter of about 2txm is prepared. The magnesium oxide content is 42%, the calcium oxide content is 0.07%, and the whiteness is is 97.3%. Xie Yinghui et al. used dolomite as raw material, calcination temperature: 930℃~1050℃, carbonization temperature: 2O℃-40℃, carbon dioxide concentration: 28%-35%, additive: alkali metal salt, pyrolysis temperature: 95~C~ IO0~C, qualified spherical magnesium carbonate was prepared.