为了研究菱镁矿在不同温度轻烧后的显微结构与活性，取粒度＜0．074 mm 的菱镁矿粉分别在850、900、950、1000、1050、1100、1150和1200℃保温2 h 煅烧制备了轻烧镁粉。采用柠檬酸溶解－EDTA 络合滴定法测定了试样中活性氧化镁的含量，...为了研究菱镁矿在不同温度轻烧后的显微结构与活性，取粒度＜0．074 mm 的菱镁矿粉分别在850、900、950、1000、1050、1100、1150和1200℃保温2 h 煅烧制备了轻烧镁粉。采用柠檬酸溶解－EDTA 络合滴定法测定了试样中活性氧化镁的含量，并利用 XRD 和 SEM对试样的物相组成和显微结构进行了分析。结果表明：在850～1050℃阶段，方镁石的晶粒尺寸增加缓慢，其活性氧化镁含量变化并不明显，均高于80％（w）；在1050～1200℃阶段，方镁石的晶粒尺寸快速增加，其活性氧化镁含量快速降低。展开更多
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
文摘为了研究菱镁矿在不同温度轻烧后的显微结构与活性，取粒度＜0．074 mm 的菱镁矿粉分别在850、900、950、1000、1050、1100、1150和1200℃保温2 h 煅烧制备了轻烧镁粉。采用柠檬酸溶解－EDTA 络合滴定法测定了试样中活性氧化镁的含量，并利用 XRD 和 SEM对试样的物相组成和显微结构进行了分析。结果表明：在850～1050℃阶段，方镁石的晶粒尺寸增加缓慢，其活性氧化镁含量变化并不明显，均高于80％（w）；在1050～1200℃阶段，方镁石的晶粒尺寸快速增加，其活性氧化镁含量快速降低。
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.
