CO2应用于炼钢的基础理论研究

CO2 is a weaker oxidizing agent compared to O2. It is possible for carbon dioxide oxidizing carbon, iron, silicon and manganese in molten bath under steelmaking temperatures and the oxidation reactions are endothermic or slightly exothermic reactions respectively. Therefore, it is possible to control the temperature and atmosphere by adopting CO2 in steelmaking processes, hence realize the aims of reducing the dust generation, purifying the liquid steel, minimizing the loss of valuable metals, saving the energy and reducing the total consumption et al.. Based on former research, theoretical calculation, experiments and numerical simulation will be used in current study, together with the examination methods including high temperature x-ray imaging and gases mass spectra--isotope gas exchange, to carry out the following studies. Thermodynamics and kinetic mechanism of the interface reaction for CO2 applying in steelmaking reactions will be investigated; the physical and chemical changes during CO2 bubbles ascent in liquid steel and the laws of melt flow will be revealed; the intensity of jet flow of CO2-O2 mixture and its effect on reaction rate will be studied; the composition and temperature variation of slag-metal system will be measured with introduction of CO2 in steelmaking process; the influence of partial pressure and flow rate of carbon dioxide on energy balance, material balance and valuable elements volatilization will be verified. Meanwhile, the results of improving the efficiency of dephosphorization, increasing the retention of metals like Fe, Cr, Ni, V and bettering the quality of liquid steel can also be realized. A theoretical model will be developed to offer basic data and theoretical foundation for applying CO2 in steelmaking processes. The completion of this project will enrich steelmaking process theory, at the same time, realize the utilization of carbon dioxide as resource in steelmaking processes.

CO2是弱氧化性气体，在炼钢温度下与碳、硅、锰等元素可发生氧化反应，并伴随吸热或微放热效应。将CO2应用于炼钢过程可实现温度及气氛控制，达到降低烟尘、净化钢液、减少有价金属损失、节能降耗等目的。课题组在前期研究的基础上，拟通过理论计算、热态实验和数值模拟，借助气相质谱-同位素气体交换、高温X射线在线成像等实验手段，探究CO2参与炼钢反应热力学及界面反应动力学；揭示CO2气泡上浮的物理化学变化及熔体流动规律；研究CO2-O2混合喷吹气体的射流强度及对反应速率的影响规律；掌握CO2应用于炼钢反应的渣-金体系温度及成分的变化；探明CO2分压及流量对热量平衡、物料平衡、有价元素挥发等的影响；实现提高脱磷效率，增加金属资源回收率和改善钢液质量等目的；建立CO2应用于炼钢单元操作的理论模型，为CO2应用于炼钢过程提供基础数据和理论支撑。课题的完成将丰富炼钢工艺理论，实现CO2在炼钢过程的资源化利用。

温室气体CO2的大量排放持续受到全世界的高度关注，本项目创造性将CO2应用于炼钢领域，深入研究了CO2应用于炼钢的基础理论。炼钢是钢铁工业非常关键的工序，完成脱碳、脱磷、升温、去夹杂等冶金任务。通过多种手段系统研究熔池内多相流反应机理，探究CO2应用于炼钢的高温特性及对冶炼规律的影响，为实现CO2在炼钢过程的应用提供理论支持，为冶金行业的节能减排和资源高值化利用提供新的途径。本项目对炼钢过程CO2的氧化反应理论、CO2用于炼钢的界面动力学、CO2-O2混合喷吹炼钢的反应工程学、CO2用于炼钢单元操作的理论模型进行了系统研究。探明了元素选择性氧化控制方法、脱碳规律及脱磷限度，揭示了CO2气泡上浮过程的物理化学变化及熔体的流动规律；通过控制CO2的混入比例，减少炼钢过程烟尘排放，提高铬、镍、钒、铁等元素收得率，并建立了CO2用于炼钢单元操作的理论模型；将多种在线测试手段直接应用于CO2炼钢的冶金反应动力学机理研究，是实验方法上的创新。