Dynamic Behavior of Sulfur in Rapid Smelting Redution of Carbon-Coated-Iron Ore

直接炼铁还原法是一种无需焦炉直接使用无结块煤和铁矿粉的炼铁新工艺，是下个世纪的新型炼铁工艺之一。开发铁矿直接冶炼还原工艺需要对反应机理的准确认识和熔融条件下的动力学评价。作为固体碳快速熔炼还原氧化铁动力学基础研究的一部分，以煤焦油为模型化合物，在氮气流中以773 K加热铁矿石与酚酞的混合物，制备了碳包覆铁矿颗粒。用滴管式反应器在1073 K-1860 K的氮气流中观察了碳包覆铁矿颗粒在快速加热过程中的还原行为。成功地模拟了快速加热过程中铁形态的变化，确定了赤铁矿经浮思体生成金属铁的连续反应动力学参数。还制备了加硫碳包铁矿石，并对快速冶炼还原过程中硫的分布进行了研究。实验结果表明，硫以FeS的形式存在于铁液相中，硫加入固体碳可以延缓金属铁的形成。

As one of the new iron-making processes for the next century, direct-iron-ore-smelting reduction process is now attracting a great deal of attention in which noncaking coal and iron ore powder can be used directly without coke oven. Development of direct-iron-ore-smelting reduction process requires accurate understanding of reaction mechanism and kinetic evaluation in melting condition.As a part of fundamental study on the kinetics of rapid smelting reduction of iron oxide with solid carbon, particles of carbon-coated-iron ore were prepared by heating of mixture of iron ore and phenolphthalein as a model compound of coal tar at 773 K in an nitrogen stream. Reduction behavior of carbon-coated-iron ore particles during rapid heating has been observed by using a drop-tube reactor in a nitrogen stream at temperatures from 1073 K-1860 K.The change in iron forms during rapid heating was successfully simulated and kinetic parameters of successive reaction for metallic iron formation from hematite via wustite were determined. The carbon-coated-iron ore with sulfur addition was also prepared and sulfur distribution was investigated during rapid smelting reduction. The experimental results showed that sulfur existed as FeS in molten iron phase and formation of metallic iron was retarded by sulfur addition to solid carbon.