In order to widen the application of microcrystalline magnesite,the thermal decomposition behavior of the microcrystalline magnesite in Sichuan and Tibet area was firstly studied by thermogravimetric analysis. Then th...In order to widen the application of microcrystalline magnesite,the thermal decomposition behavior of the microcrystalline magnesite in Sichuan and Tibet area was firstly studied by thermogravimetric analysis. Then the effects of the calcination temperature,calcination time and particle size on the preparation of active Mg O from microcrystalline magnesite were studied by orthogonal experimental design. At last,high purity sintered magnesia was prepared by two-step calcination,meanwhile the effects of the light burning temperature,particle size of the light-burned Mg O powder,molding pressure and the hydration rate of light-burned Mg O powder on the properties of high purity sintered magnesia were studied.The results show that:( 1) the calcination temperature has the greatest influence on the activity of light-burned MgO,followed by the holding time and the particle size;the optimal process of light burning for preparing active MgO is the microcrystalline magnesite with particle size of 1-0. 5 mm heat-treating at 700 ℃ for 2 h; under these conditions,the microcrystalline magnesite decomposes completely; the average grain size of the obtained product is about 21. 4 nm,and its activity of CAA is20. 16 s;( 2) the effect of the light burning temperature on the density of high purity sintered magnesia is not obvious; the fineness of the light burning Mg O powder and molding pressure help to increase the density of sintered magnesia; the lower the hydration rate of the lightburned Mg O, the higher the density of the sintered magnesia; the high-purity sintered magnesite withw( MgO) ≥98% and bulk density≥3. 40 g/cm;can be prepared by the two-step calcination; the grains are fine with size of 30-200 μm and the impurity at grain boundaries is little.展开更多
以轻烧镁为原料,经消化、碳化、除杂、热解及煅烧制备出高纯氧化镁,并确定了适宜的工艺条件:活性炭用量为20 g/L,时间60 m in;活性炭吸附除杂温度20℃,时间80 m in;热解温度100℃,时间20 m in,升温速率均匀缓慢;煅烧温度950℃。氧化镁...以轻烧镁为原料,经消化、碳化、除杂、热解及煅烧制备出高纯氧化镁,并确定了适宜的工艺条件:活性炭用量为20 g/L,时间60 m in;活性炭吸附除杂温度20℃,时间80 m in;热解温度100℃,时间20 m in,升温速率均匀缓慢;煅烧温度950℃。氧化镁产品中氧化镁质量分数可达99.5%,氧化钙质量分数小于0.09%,铁的质量分数小于0.05%,产品中粒度小于5μm的粒子质量分数达到72.3%。SEM分析表明,低温热解氧化镁为针状,高温热解氧化镁为球状。展开更多
文摘In order to widen the application of microcrystalline magnesite,the thermal decomposition behavior of the microcrystalline magnesite in Sichuan and Tibet area was firstly studied by thermogravimetric analysis. Then the effects of the calcination temperature,calcination time and particle size on the preparation of active Mg O from microcrystalline magnesite were studied by orthogonal experimental design. At last,high purity sintered magnesia was prepared by two-step calcination,meanwhile the effects of the light burning temperature,particle size of the light-burned Mg O powder,molding pressure and the hydration rate of light-burned Mg O powder on the properties of high purity sintered magnesia were studied.The results show that:( 1) the calcination temperature has the greatest influence on the activity of light-burned MgO,followed by the holding time and the particle size;the optimal process of light burning for preparing active MgO is the microcrystalline magnesite with particle size of 1-0. 5 mm heat-treating at 700 ℃ for 2 h; under these conditions,the microcrystalline magnesite decomposes completely; the average grain size of the obtained product is about 21. 4 nm,and its activity of CAA is20. 16 s;( 2) the effect of the light burning temperature on the density of high purity sintered magnesia is not obvious; the fineness of the light burning Mg O powder and molding pressure help to increase the density of sintered magnesia; the lower the hydration rate of the lightburned Mg O, the higher the density of the sintered magnesia; the high-purity sintered magnesite withw( MgO) ≥98% and bulk density≥3. 40 g/cm;can be prepared by the two-step calcination; the grains are fine with size of 30-200 μm and the impurity at grain boundaries is little.
文摘以轻烧镁为原料,经消化、碳化、除杂、热解及煅烧制备出高纯氧化镁,并确定了适宜的工艺条件:活性炭用量为20 g/L,时间60 m in;活性炭吸附除杂温度20℃,时间80 m in;热解温度100℃,时间20 m in,升温速率均匀缓慢;煅烧温度950℃。氧化镁产品中氧化镁质量分数可达99.5%,氧化钙质量分数小于0.09%,铁的质量分数小于0.05%,产品中粒度小于5μm的粒子质量分数达到72.3%。SEM分析表明,低温热解氧化镁为针状,高温热解氧化镁为球状。