微波强化硅热还原铬铁矿粉行为及机理研究

Low carbon ferrochromium is the important addition material in making special steels. The traditional silicothermic process and oxygen-blown process are have the disadvantages of long process and high energy consumption.The methods of silicothermic reduction chromite ore powders in microwave field is put forward by using characters of microwave, which has the advantages of heating materials quickly,lower reduction temperature, reducing reaction time, energy efficiency, clean and no pollution, and so on, and shorten the process, lower the energy consumption.The behavior and mechanism of silicothermic reduction chromite ore powders in microwave field was studied in this work. Besides that, the effects of microwave power density, granularity of raw materials, reduction time and temperature, amount of reduction agent and flux on the heating performance and reduction rate of silicothermic reduction chromite ore powders in microwave field, chromium recovery are explored. The migration rule of impurities to slag phase is explored, and the basic theory of silicothermic reduction chromite ore powders in microwave field is formed, which could enrich the theoretical system and basic research of the microwave metallurgy. The program will open up a green approach for making ferrochromium with short process, it has important research value and broad application prospect.

中低碳铬铁是生产特种钢很重要的添加料，目前常规工艺采用的硅热法和吹氧法均需对铬铁矿粉先造块再冶炼，存在工艺流程长、能耗高等缺点。项目利用微波特殊的加热机制，充分发挥其加热物料升温快、还原温度低、时间短、能源利用率高、清洁无污染等优点，提出微波场中硅热还原铬铁矿粉的方法，直接生产中低碳铬铁，从而缩短工艺流程实现节能降耗。研究以微波加热还原含硅铬铁矿粉为主要内容，得到微波场功率密度、原料粒度、还原时间及温度、还原剂用量等各主要因素对微波场中含硅铬铁矿粉的升温性能、还原率、铬回收率等影响规律，揭示微波场中杂质组元迁移至渣相的过程，形成微波场中硅热还原铬铁矿的技术基础理论，丰富微波冶金的理论体系和基础研究。项目的开展将为短流程冶炼铬铁开辟绿色途径，具有重要的研究价值和应用前景。

中低碳铬铁是生产特种钢很重要的添加料，目前常规工艺采用的硅热法和吹氧法均需对铬铁矿粉先造块再冶炼，存在工艺流程长、能耗高等缺点。项目利用微波特殊的加热机制，充分发挥其加热物料升温快、还原温度低、时间短、能源利用率高、清洁无污染等优点，提出微波场中硅热还原铬铁矿粉的方法，直接生产中低碳铬铁，从而缩短工艺流程实现节能降耗。项目通过研究微波场中硅热还原铬铁矿粉原理及工艺研究，得到各主要因素对微波加热还原含硅铬铁矿的升温性能、还原速率及效率、铬回收率、铬铁微观结构等影响规律，形成微波场中硅还原铬铁矿的技术基础理论，丰富微波加热还原铁矿石的理论体系和基础研究，得到的结论如下：.（1）含硅铬铁矿粉微波电磁特性的研究表明，随着粒度的不断减小，铬铁矿粉的介电特性变好；硅铁合金粉和钙质石灰的介电特性优于硅粉和镁质石灰；随着表观密度的不断增大，物料的介电特性随之增强；当硅氧比为1.80时，混合物料的介电特性最好。.（2）微波场中硅热还原铬铁矿粉工艺研究结果表明，颗粒尺寸越小、还原时间越长、还原温度越高、微波功率越大、还原剂用量越多、料层越薄，铬金属化率越高。.（3）硅热还原铬铁矿粉的工艺过程热力学研究结果表明，微波场中硅热还原过程中Cr2O3的还原顺序按Cr2O3→CrO→Cr的次序进行；通过对产物扫描电镜的分析得出，当温度在1100℃时Cr-Fe合金形核，当温度达到1200℃时，出现大量的亮白色金属；当温度高达1300℃时，铬铁合金的形成过程基本结束，且得到的金相产物为低碳铬铁合金，其主要化学成分满足(GB5683-87) FeCr55C25Ⅱ的要求。.