Application Of Dolomite-Preparation And Analysis Of Nanometer Magnesium Oxide And Diamond Shape Magnesium Hydroxide

Dolomite is one of the most important raw materials of preparing for the series of magnesium because it is widely distributed, rich stored, of high quality, easily exploited. With the development of technology, the exploitation and application of dolomite has deep into various fields and the dolomite becomes a kind of economical mineral resources. At present, the development and utilization of dolomite get more attention and its application is widely, including chemicals, metallurgy, building material and some other industries.Nanometer magnesium oxide possesses particular properties of electrical, magnetic, thermal and optical, which is different from body material because of the characteristics of small size effect, surface effect, quantum size effect and macroscopic quantum tunnel effect. The dolomite was used to prepare the nanometer magnesium because of the advantages of low cost and simple operation.Magnesium hydroxide is used widely in material processing, environmental protection and medical treatment.The normal magnesium hydroxide is amorphous, easily aggregation and difficult to affinity with the organic phase. The special magnesium hydroxide can be used as flame retardant and reinforcing material because of the characteristics of low surface energy, strong mechanical strength and high elastic modulus.In this dissertation, the application method and prospect of the dolomite was discussed, which provides reference value to the industrialized preparation of magnesium compounds.The main research contents are as follows.1.The effect of calcination and digestion process of dolomite on the activity of magnesium oxideThe particles of active magnesia was prepared by controlling calcining temperature, holding time, soaking time, hydration temperature and using dolomite as raw material.The impact of calcining dolomite and hydration methods on the activity of dolomite was studied and the best conditions for calcining and hydration was exploited. The activity of products was measured by the citrate route. It was found that high active magnesia could be prepared at 950℃for 1.5 h. Moreover, the highest activity of the hydration product which were prepared on the optimum calcination conditions could be found on condition that the magnesia was hydrated at 80℃for 30 min. This method was simple aer use of dolomite for magnesnd convenient to operate, which provides an important reference value to the furthium hydroxide and magnesia preparation.2.Brine-dolomite method was used in preparing nanometer magnesiumThe brine-dolomite method was applied and the refined commercial brine was used as raw material.The precipitant was obtained by calcination and hydration of dolomite. Surfactant was added to prepare nanometer magnesia. The effect of reaction temperature, brine concentration, and the amount of surfactant were discussed, and the product was characterized by XRD, TG-DTA and SEM etc. The results show that nanometer magnesia with a diameter of 50 nm was obtained at 60℃,on condition that brine density was 1.0 mol·L-1 and the additive amount was 0.3 %.Moreover, the obtained nanometer magnesia was in high purity and good dispersion property, and has a cubic crystal structure. This method was low cost, simple technology, easily obtained the raw materials and friendly to environment, which provides an important reference value to the further use in industrialization.3.Diamond shape magnesium hydroxide was prepared by dolomite with carbon dioxide and ammonia method.Dolomite was used as raw material for preparing diamond shape magnesium hydroxide with carbon dioxide and ammonia method. The effect of carbonization time, carbonization temperature, the concentration of Mg(HCO3)2, hydrothermal synthesis time and temperature on the product were discussed. By means of adding crystal changing reagent, the generating direction of magnesium hydroxide crystal was controlled and the flake, cluster magnesium hydroxide was prepared. The particular appearance magnesium hydroxide has a certain development prospect in the study of inorganic additive non-toxic flame retardant and industrial application because the preparation is simple, low cost and friendly to the environment.