Hydromagnesite (4MgCO3 Mg(OH)2 4H2O) is a natural carbonate mineral with abundant reserves and low CaO content. It is a high-quality mineral raw material for the preparation of reactive magnesia. The limitation of factors increases the difficulty of mining hydromagnesite ore, so far there are not many domestic researches on it. Therefore, how to develop and utilize hydromagnesite resources to prepare a series of high-quality magnesium-based compounds is the biggest problem at present. Tibet Mag used hydromagnesite as raw material to explore the activity of the product magnesium oxide under different calcination conditions.
During the calcination process, hydromagnesite loses crystal water and hydroxyl groups, releases CO2, and generates magnesium oxide powder at the same time. Magnesium oxide obtained under different calcination conditions often has different reactivity, resulting in differences in its hydration ability. The activity of the calcined product was determined by two methods of citric acid method and hydration method.
The results show that the calcination temperature and holding time have a greater impact on the activity of magnesium oxide, followed by the heating rate. Finally, the optimal calcination conditions were determined as calcination temperature 600℃, holding time 0.5h and heating rate 10℃·min~(-1). The hydration kinetics of the high-activity magnesium oxide obtained by calcining under optimal conditions was used as the raw material to study the hydration kinetics, and the hydration curves of magnesium oxide at 25°C, 45°C, and 65°C were obtained from the experiment, and the obtained hydration rate data were compared with different Kinetic equation fitting.
Tibet Mag conducted analysis and research on the calcination of hydromagnesite, and determined the optimal calcination conditions for the preparation of reactive magnesia by setting different calcination parameters (including calcination temperature, holding time and heating rate).
The activity of the calcined product was characterized by two activity determination methods, citric acid method and hydration method. The citric acid method is simple and easy to operate, but the disadvantage is that the color judgment of the titration end point will cause relatively large errors. The hydration method characterizes the activity of magnesium oxide by comparing the mass change before and after the reaction, and the error is relatively small.
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