Research Of Preparation Of High Purity Light Magnesium Oxide From Microcrystalline Magnesite

Magnesium oxide is a commonly used inorganic chemical material.With the development of fine chemical industry,there is a big gap in the demand for high-end magnesium oxide in China at present.Magnesium oxide produced by calcination of magnesite has a simple process,but the early brutal plunder resulted in a serious waste of resources,leading to the lack of high-quality magnesite resources in China,low added value of products,and unable to meet the domestic demand.The microcrystalline magnesite mined in Sichuan and Tibet in China has low impurity content and few kinds,which is an ideal raw material for preparing high-end magnesium compound products.It is of great significance to make full use of the advantages of this kind of mineral resources and fill the gap in China’s high-end magnesium oxide market.In this study,the advantages of microcrystalline magnesite in Sichuan and Tibet in China were utilized to explore the possibility of its application in high grade and high added value fields through preliminary exploration of the hydration kinetics of light burning magnesium oxide,and by means of hydration purification and refiring of hydration products.The research contents mainly include three aspects: the study of the hydrating energy and the hydrating rate control type of the lightly fired magnesium oxide;Using magnesium acetate as hydration agent,;the hydration process(hydrating agent dosage,hydration temperature,hydration time,solid-liquid mass ratio,etc)was optimized by orthogonal test;The effect of calcination temperature on the properties of magnesium oxide was studied and the high purity and light magnesium oxide was prepared.Based on the above research,the apparent activation energy of light sintering powder calcined at 920℃ for 2h was determined to be 41.5k J/mol,and the reaction type belongs to chemical reaction control type.The optimized hydration process was as follows: magnesium acetate content of 5%,reaction temperature of 25℃,reaction time of 60 min,solid-liquid ratio of 1:8;Under this process,the hydration rate of magnesium oxide is about 94.3%,and the purity of magnesium oxide is about 99.66% after cauterization.After calcined at 500℃ for 2h,the bulk densities of the hydrated products was 0.23g/ m L at D50 was 8.94μm,D90 was28.36μm,at D50 4.50μm,D90 14.70μm,the bulk densitieswas about 0.18g/ m L,which meet the standard of light magnesium oxide.By changing the temperature and time of secondary refiring,magnesium oxide products with medium and high activity and medium and low activity could be prepared.After calcining at 600℃ for 2h,the active magnesium oxide ratio of the hydration product reached the maximum value was about 90.1%.Compared with the lighter powder,the active ratio increased 5.4%.High purity and light magnesium oxide products with different properties can be prepared by hydration purification and secondary refiring.