Study On The Preparation Of Ultrafine Magnesium Hydroxide

The particle size of ultrafine magnesium hydroxide is about. 100nm～1000nm, Ultrafine magnesium hydroxide has active surface-free energy, magnesium hydroxide is used to form coacervate, its particle size is about 10-100μm. In this thesis, according to the quality of the raw material and the demand of the production, the whole experimental process includes two sections.In the first section, the results reveal that some factors, for example filtration of ammonium chloride, composition of hydrothermal solvent, hydrothermal time, hydrothermal temperature have important effect on the morphology of final products. These conclusions can guide the further theoretical research and industrial production of magnesium hydroxide crystal.(1) Through the single factor and the orthogonal test, the technology of preparation ultrafine magnesium hydroxide is further studied. The optimal process conditions are as follows:the raw materials are AR NH3H2O and AR MgSO4, Z17 as the disperser,and the molar ratio of NH3H2O to MgSO4 is about 2:1 (over ammonia), the adequate amount of Z17 is 0.3% of total reactants amount, reaction temperature is 50℃,reaction time is 30min, constant temperature is 80℃and processing time is 90min, the production is dried at 120℃for 120min, magnesium hydroxide can be refinede by filtration and washing with alcohol.(2) According to the results of experience data, an optimal experimental process is designed. The preparation of ultrafine magnesium hydroxide in direct precipitation method with low quality NH3H2O and MgSO4 and Z17 as disperser. The optimal process conditions are as follows:the raw materials are NH3-H2O and MgSO4, Z17 as the disperser,and the molar ratio of NH3H2O to MgSO4 is about 2:1 (over ammonia), the adequate amount of Z17 is 0.3% of total reactants amount, reaction temperature is 55℃,reaction time is 30min, constant temperature is 80℃and processing time is 90min, the production is dried at 120℃for 120min, magnesium hydroxide can be refinede by filtration and washing with alcohol. And the production is dispersed by ultrasonic.The ultrafine magnesium hydroxide is characterized by x-ray powder diffraction and laser-diffraction diameter test. When adequate amount of Z17 is 0.3% of total reactants amount, and the product is dispersed by ultrasonic to obtain well dispersed, and average size of ultrafine magnesium hydroxide is 80nm.It is possible that the ultrafine magnesium hydroxide is obtained through direct precipitation method. This optimal experimental process can guide the further theoretical research and industrial production of magnesium hydroxide crystal.