Activity is not only an important physical and chemical property of magnesium oxide, but also an important indicator to measure magnesium oxide used in the rubber industry. In other words, the heavy weight is pure MgO, and the light weight is xMgO•yMg(OH)2, that is, basic magnesium oxide. Among them, the percentage content of light magnesium oxide plays an important role in the activity.

　　Generally speaking, high-activity magnesium oxide is obtained by decomposing basic magnesium carbonate at low temperature for a long time. The furnace structure is special, the energy consumption is high, and the apparent specific volume of the obtained product is also large. In addition, there is also the use of microwave radiation to prepare high-activity magnesium oxide with an iodine absorption value higher than 170 mgI2/gMgO from light magnesium oxide. The apparent specific volume of the highly active magnesium oxide is relatively small, 2.5-3.3 ml/g. 

　　Activated magnesium oxide is mainly used as an activator and accelerator for butyl rubber, neoprene rubber, fluororubber, and nitrile rubber, and is also one of the main auxiliaries for paints, adhesives, plastics and other products. With the development of science, technology and economy, activated magnesium oxide has been used more and more widely, and while the dosage is increasing day by day, the requirements for product activity are also more and more diverse. Magnesium oxide activity.

　　There are many methods for domestic production of magnesium oxide, such as seawater-lime method, brine-soda ash method, brine-carbon ammonia method, dolomite, magnesite-carbonization method, etc. Regardless of the production method used, the activity of magnesium oxide is related to the production process. There are many factors affecting the activity, such as internal lattice defects, specific surface area, production methods and other factors. Taking the brine-soda ash method as an example, the activity of magnesium oxide has a great relationship with the reaction temperature, pyrolysis temperature, reaction concentration (soda ash, brine), pressure, water control, and dehydration time after pyrolysis.

　　However, the control of the activity of magnesium oxide is mainly in the calcination process of the intermediate magnesium carbonate. Calcination at 600-700°C can produce highly active magnesia. At 650°C, the maximum activity occurs. The temperature at which the maximum activity occurs depends on the heating time and heating rate, especially the temperature. Slow and continuous heating can provide the maximum activity. The lattice of newly activated magnesium oxide is compact, has a high specific surface area, and is also porous. The maintenance of the magnesium carbonate composition constitutes a high activity. Further heating will reduce the surface area and porosity, and the internal structure will sinter. At relatively high temperatures, dead-burned magnesia is produced. Decomposition kinetics verify that the process starts outside the crystal; thermodynamics explaining the properties of activated magnesia is the balance between the rate of active species produced and the sintered magnesia. Calcination of basic magnesium carbonate at 650℃ can generate extremely active magnesium oxide with a specific surface area of ​​about 100m2/g. At 700 °C, all the magnesia has formed; above 700 °C, the porous structure begins to shrink and the total area decreases. Secondly, when the oxide reaches the maximum amount, the specific surface area also reaches the maximum amount.

　　The research shows that the calcination temperature has an effect on the activity of magnesium oxide. The calcination temperature, the rate of temperature rise, and the residence time have a great influence on the continued decomposition of carbonate. At 700 °C, there will be a turning point of the maximum rate, and the residence speed and time are related to the surface area of magnesium oxide. With the increase of temperature, at 900-1000 ℃, calcination of basic magnesium carbonate produces magnesium oxide with low activity.