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研究了空气氛围中热处理天然菱铁矿在不同煅烧温度、时间的结构演化规律。结果表明:当煅烧温度达到约430℃时,矿石中的亚铁离子被轻微氧化,随即释放少量CO_2,此时菱铁矿矿石表面逐渐出现多孔结构状态,孔径为几个纳米,呈现形态为不规则的串珠状;当煅烧温度达到460℃时,开始大量释放CO_2并逐渐相转变为赤铁矿,并在595℃时完全相转变。400~600℃的煅烧产物比表面积和孔结构随着煅烧温度、时间的变化有较为明显的差异。其中470℃煅烧产物由于大量脱去CO_2,菱铁矿颗粒内部出现大量1~5 nm的介孔,最大比表面积为57.5 m2/g;随着煅烧温度增高、时间延长,赤铁矿晶粒逐渐变大,其晶粒间空隙孔径变大、数量减少,比表面积逐渐降低。天然菱铁矿可以在450~500℃空气氛围中快速热分解获得高比表面积纳米孔材料。
The structure evolution of natural siderite treated by air in different calcination temperature and time was studied. The results show that when the calcination temperature reaches about 430 ℃, the ferrous ions in the ore are oxidized slightly, and then a small amount of CO 2 is released. At this time, the surface of siderite ore gradually appears porous structure with pore size of several nanometers, Rules beaded; when the calcination temperature reaches 460 ℃, began to release a large number of CO 2 and gradually transformed into hematite, and complete phase transition at 595 ℃. The specific surface area and pore structure of calcined product at 400-600 ℃ have obvious differences with the calcination temperature and time. Among them, a large amount of mesopores with a size of 1 ~ 5 nm appeared in the siderite of 470 ℃ and a maximum specific surface area of 57.5 m2 / g due to the large amount of CO_2 removed. With the increase of calcination temperature and time, the hematite grains gradually Becomes larger, the intergranular pore diameter becomes larger, the number decreases, and the specific surface area decreases gradually. Natural siderite can be 450 ~ 500 ℃ in the air atmosphere rapid thermal decomposition to obtain high specific surface area nanoporous materials.