【作者】 王华；

【导师】 黄柱成； 彭虎；

【作者基本信息】 中南大学 ， 矿物加工工程， 2011， 硕士

【摘要】 随着世界钢铁工业的快速发展,以高炉为主导的炼铁流程已经发展到鼎盛时期,具有技术成熟、生产能力大、效率高等优点,但是由于其流程长、投资大、能耗高、污染重等缺点,在焦煤短缺、价格昂贵的当今世界,开发清洁、高效的非高炉炼铁工艺已成为当务之急。本论文进行了铁氧化物微波场中升温行为及其煤基直接还原基础研究,为开发微波加热氧化球团煤基直接还原新工艺提供理论指导。与传统加热方式不同,微波加热是利用电磁场中冶金物料的介电损耗和磁损耗使物料整体加热。升温试验结果表明：铁及其氧化物粉末和团块都是良好的微波吸收体,并且团块在微波场中的升温快于粉末的升温,它们在微波场中的升温可分为前后两个阶段——快速升温阶段和缓慢升温阶段,前段升温速率顺序为：Fe3O4>FeO>Fe>Fe2O3。其中Fe2O3粉末和团块前段升温缓慢,后段升温速度加快；而Fe3O4、FeO、Fe粉末及其团块前段升温较快,后段升温较慢。氧化球团和无烟煤也是良好的微波吸收体,并且无烟煤的升温快于氧化球团的升温。在不同微波功率、质量和粒级条件下对氧化球团和无烟煤进行升温性能研究,结果表明：当功率为1.3KW、球团质量为160g、粒级为12-16mm时升温速率最快,温度升至1050℃C的时间为42min；当功率为1.3KW、无烟煤质量为80g、混合粒级时升温速率最快,温度升至1080℃的时间为43min。研究了脉石成分在微波场中对Fe2O3团块或氧化球团的升温特性和还原过程的影响,结果表明：SiO2、Fe2O3在团块中吸收微波出现“叠加效应”,使升温速率变快；氧化球团中的脉石成分会引起局部的“热应力”,导致球团内部产生裂纹,有利于还原气体的扩散。采用扫描电镜分析了在微波作用下铁及其氧化物的结构性能变化,揭示了颗粒之间存在相互迁移、长大的规律。在微波输入功率为1.3KW条件下,Fe2O3团块温度升高到1050℃时,Fe2O3颗粒直径从0.25μm长大至1.2μm；Fe3O4团块温度升高到650℃C时,颗粒直径从1μm长大至7μm。微波作用后铁及其氧化物团块的强度顺序为：Fe> Fe3O4>FeO>Fe2O3。对Fe203团块和氧化球团微波加热煤基还原试验进行了研究,结果表明：随着还原终点温度和C/Fe的增加,还原团块与还原球团的金属化率、金属铁含量以及全铁含量也随之增加。更多还原

【Abstract】 With the quickly development of steel industry in the world, the ironmaking process flow which with blast furnace as the dominant is very boom, maturate, high efficiency. Howeve, because of the long flow, biggest financial, high power consumption, nowadays, in the world where coking coal is shortage and expensive, we should development non blast furnace which clear and high efficiency as early as possible, thus the paper comes to study on the temperature rising behavior and coal-based direct reduction of iron oxides in microwave field, in the interest of providing the theoretic guidance for developing the new technique of the coal-based direct reduction of iron oxide pellet heated by microwave.Different from traditional heating, microwave heating uses the dielectric loss and magnetic loss to heat. The result of rising temperature shows:iron and iron oxide powders and briquettes are all good microwave absorbers, and the rising temperature rate of briquettes is quicker than the one of pellets, the rising temperature can be divided to two stages of fore period and late period:quick rising and slow rising. The order of fore period rising temperature rate is:Fe> Fe3O4>FeO >Fe2O3. Fe2O3 powder and briquette rising temperature is very quick in fore period, and is very slow in late period; Fe3O4, FeO and Fe powders and briquettes rising temperature is very quick in fore period, but are all slow in later. Iron oxide pellets and anthracite are both good microwave absorbers, and the rate of anthracite is quicker than iron oxide pellets. To study the temperature rising characteristics under different microwave powers, weights and sizes, the result shows:when microwave input power is 1.3KW and the temperature coming to 1050℃, the rate of the pellets of 160g and 12～16mm is the quickest, using 42 minutes; when microwave input power is 1.3KW and the temperature coming to 1080℃, the rate of the anthracite of 80g and admixture grade is the quickest, using 43 minutes.To study on the influence of gangue on the temperature rising characteristic and the reduction process of Fe2O3 briquettes and iron oxide pellets in microwave field, the result shows: SiO2 and Fe2O3 in briquette absorb microwave with superimposition effect, which results in an increase in the temperature rising rate; the partial thermal stress caused by gangue in pellets results in plenty of cracks, which in favor of the quick reduction.The structures and properties of iron and iron oxides under microwave radiation are analyzed by the SEM. It is revealed that there are the laws of intermigration and grow between grains of iron and iron oxide. When microwave input power is 1.3KW and temperature is 1050℃, the diameter of Fe2O3 grains changes from about 0.25μm to about 1.2μm; when temperature is 650℃, the diameter of Fe3O4 grain change from about 1μm to about 7μm. After microwave radiation, the order of the briquettes compressive strength is: Fe> Fe3O4>FeO>Fe2O3.To test on Fe2O3 briquettes and iron oxide pellets with anthracite heated by microwave, the result of reduction shows: with the rising of end point temperature and C/Fe, the metallization, the metal iron content and total iron content of briquettes and pellets increase.更多还原