【作者】 郭小水；

【导师】 刘家祥； 李敏；

【作者基本信息】 北京化工大学 ， 材料纳米技术， 2008， 硕士

【摘要】 氧化镁高温下具有优良的耐碱性和电绝缘性、光透过性好、导热性高、热膨胀系数大等特点,广泛用于橡胶、电子、化工、陶瓷等行业。高纯氧化镁是指纯度大于98%的氧化镁产品,它具有比普通轻质氧化镁更优异的性能,因而应用领域扩大到航空航天及高级陶瓷等领域。以武汉钢铁集团有限公司乌龙泉矿生产的-5mm轻烧白云石粉料为原料,采用碳化法制备氧化镁。研究了原料消化、碳化、重镁水热解和碱式碳酸镁煅烧工艺过程,分析了各过程的影响因素,得出最佳工艺条件。分析得出影响氧化镁纯度的主要因素为重镁水热解温度,并采用两种方法对重镁水热解过程进行改进制备出高纯氧化镁。在重镁水热解过程中加入乙醇,制备出高纯氧化镁。研究了乙醇用量、热解温度对氧化镁纯度、氧化钙含量和氧化镁回收率的影响,表明氧化镁纯度随乙醇用量的增大和热解温度的上升而降低,氧化钙含量和氧化镁回收率则上升。得出最佳工艺条件:乙醇40%(体积含量)、温度50℃,此条件下氧化镁纯度为99.78%,氧化钙含量为0.23%,氧化镁回收率为63%。在低压条件下热解重镁水,制备出高纯氧化镁。研究了液面压强对氧化镁纯度、氧化钙含量和氧化镁回收率的影响,表明氧化镁纯度随液面压强的上升而下降,氧化钙含量则随之增大,氧化镁回收率不变。得出最佳工艺条件:压强0.015MPa,此条件下氧化镁纯度为99.6%,氧化钙含量为0.13%,氧化镁回收率为70%。用乙酸溶解碱式碳酸镁得到乙酸镁溶液,经浓缩、结晶得到乙酸镁晶体。将乙酸镁晶体干燥后在500℃煅烧30min得到纳米氧化镁。XRD表征表明样品为立方晶系,衍射峰发生宽化。TEM照片表明颗粒大小约50nm,边缘较清晰。更多还原

【Abstract】 Magnesia is wildly used in rubber,electron,chemistry and ceramic areas because of its good alkali resistance,good electricity isolation,good heat transmission and big heat expand quotiety and so on.High-purity magnesia, MGO＞98%,has much more excellent characteristics than common magnesia in many cases and is used even in high-technology areas such as space and fine ceramic.Nanometer magnesia is a new functional and fine inorganic nonmetal material appeared with development of nanometer technology.Magnesia prepared is by dolomite carbonation from light burning dolomite powder（-5mm）produced in Wulongquan mine.The optimal conditions have been confirmed after studying four processes of dolomite carbonation,that are hydrating,carbonating,thermal decomposition and burning.The main factor that influences the purity of magnesia is the thermal decomposition temperature of carbonated liquid.Finally high-purity magnesia has been prepared by dolomite carbonation improved on thermal decomposition process by two ways,adding ethanol and declining pressure.Adding ethanol during carbonated liquid thermal decomposition process, high-purity magnesia has been prepared.It has been studied that the influence of ethanol quantity and temperature on the purity of magnesia,CaO content and rate of MgO product yield.The result shows the purity of magnesia declines with increasing of ethanol quantity and temperature,but CaO content and the rate of MgO product yield increase.At last the optimal conditions, ethanol:40%and 50℃have been confirmed.The purity of magnesia prepared under the optimal conditions is 99.78%,CaO is 0.23%,product yield of MgO is 63%.Thermal decomposing carbonated liquid under low pressure can prepare high-purity magnesia.It has been studied that influence of pressure on purity of magnesia,CaO content and rate of MgO product yield.The conclusion indicates the purity of magnesia declines with increasing of pressure,CaO content increases too,but the rate of MgO product yield is invariable.At last the optimal condition is at pressure of 0.015MPa.The purity of MgO sample prepared under optimal conditions is 99.6%,CaO content is 0.13%,product yield of MgO is 70%.Preparation of nanometer magnesia is based on the characteristic of magnesium acetate vaporizing and decomposing to MgO at 323℃.Precursor Mg（acac）₂ has been prepared by reaction of acetic acid and magnesium hydroxyl carbonate.Then nanometer MgO has been obtained through making the dry precursor decompose at 500℃for 30min.XRD shows MgO is cubic structure crystal and peaks have obviously broadened.TEM pictures shows particle size of nanometer MgO is about 50nm,and boundaries between MgO更多还原