Preparation And Analysis Of Nano-magnesium Hydroxide By Brine Caustic Soda Method And Preparation Of Heavymagnesium Oxide

The brine containing magnesium resource is rich in our country, and magnesium mostly exists in forms of magnesium ions. As the development of sea and salt lake resources, a large number of waste brine is produced and brings pollution to the environment, so we should do something to prevent it. For example, do our best to use it and let it do useful things for us. Nanometer material is a new material in twenty-first century, because the characteristics of its small size, large surface area, morphology diversity and so on, so it has special photoelectric or chemical nature. Therefore, the nanometer materials of Magnesium compound are widely concerned now.Nanometer magnesium hydroxide powder is a kind of important inorganic materials, because it can be broken down into magnesium oxide and water, it can be used as a smoke-free,non-toxic and anti fuel filling material, in addition, it has strong neutralization ability, so it is applied widely in medicine. Generally, the particle size of highly active magnesium oxide is smaller than 2000nm, and the reaction time with citric acid is less than 25seconds, besides, the optical, electrical and magnetic characteristics of highly active magnesium oxide are different from the general magnesium oxide. In medicine, it can be used as adjuvant additive in drugs, which can be used to treat gastrointestinal diseases; in environmental protection, it can be used as efficient dissociation adsorbent to adsorb organic phosphorus substances, acid gas and toxic chemical substances. In this paper, nanometer magnesium hydroxide and activated magnesium oxide powders were prepared by using brine and Sodium hydroxide oxide in different experimental conditions, the heavy magnesium oxide was also prepared, which bulk density is greater than0.5g/ml. The main research contents include the following several points:1.Nanometer magnesium hydroxide powder is prepared by direct precipitation method with brine and caustic soda.Nanometer magnesium hydroxide powder is prepared by direct precipitation method with brine and caustic soda. The reaction temperature, reaction time, reaction concentration and drying methods and so on were studied in the experiment. The powder’s particle size is measured by laser particle analyzer and the morphology characteristics are analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). Finally, the powder’s thermal stability is analyzed by thermal gravimetric analyzer. The result shows that, the nanometer magnesium hydroxide of high purity, small size, loose and scattered slices is prepared in the optimal experiment condition. The thickness is about 10nm and about 150nm in diameter.2. Brine-alkali method to prepare active magnesium oxide powder in different conditionThe magnesium hydroxide is prepared with the raw material of brine and sodium hydroxide; magnesium oxide is got by heating magnesium hydroxide, and its activity is measured by citric acid method. Firstly, the drop way is determinded by measureing magnesium oxide’s activity in this paper. Secondly, the reaction temperature, reaction time, reaction concentration and drying methods and so on are studied in the experiment to determine the optimal experiment condition. Finally, magnesium oxide’s morphology characteristics are analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM). The study found that active magnesium oxide of small particle size; high dispersion and porous surface can be prepared in the optimal experiment conditions. The reaction time is about 8 seconds (CAA=8s).3. Direct precipitation method to prepare heavy magnesium oxide with brine and mixed alkaliMagnesium oxide is prepared with brine and sodium hydroxide or sodium carbonate or the two mixed alkali and its bulk density is measured to determine the best base. By controlling the amount of mixed alkali and changing the preparation condition such as reaction temperature, reaction time, reaction concentration, drying methods and so on and measuring its bulk density to determine the best preparation condition. The result shows that heavy magnesium oxide which bulk density is about 1.527g/ml can be got when sodium hydroxide and sodium carbonate in a molar ratio of 1:3, the reaction temperature at 60℃, the heating temperature at 850℃ and heating 2 hours.