含铁熔渣还原提铁过程中热物性演变及其对金属液滴动力学行为的影响

Molten metallurgical slags discharged at high temperature contain a great quantity of physical heat and metal mineral resources, and it is one of the important comprehensive utilization ways to extract valuable metals by making full use of the waste heat. In the proposed project, for the purpose to clarify the thermophysical properties evolution of CaO-SiO2-FeOx-Al2O3-MgO slag system during the reduction process for iron recovery and the effects on the dynamics behavior of melt droplet, a systematically fundamental research is to be carried out on the basis of metallurgical melt theory, metallurgical macro-kinetic theory and transport theory. The dissolution kinetics as well as heat and mass transport of the oxide components from aluminium ash and reduction product, variation of the phase composition and slag microstructure during reduction process, evolution of thermophysical properties of the molten slag, effects of thermophysical properties on the dynamics behavior of melt droplet, and macro-kinetics of molten iron-containing slag reduction by aluminium ash are to be studied. The evolution of thermophysical property during the reduction process is to be confirmed, and the controlling mechanism of thermophysical property optimization by adjusting the slag composition is to be identified. Meanwhile, the acting relation between the thermophysical properties and slag microstructure are to be established. In addition, impacting mechanism of the thermophysical properties on the dynamics behavior of melt droplet is to be clarified. The research results with high scientific relevance and practical value are to be used to enrich the thermophysical properties of high temperature melts and also as the theoretical basis for the development of feasible technology for smelting reduction treatment process of iron-containing metallurgical slag.

高温排放的冶金熔渣蕴含大量物理热和金属矿物资源，利用熔渣余热实现有价金属的提取回收是冶金渣综合利用的重要途径。本项目拟以含铁熔渣铝灰还原提铁过程中CaO-SiO2-FeOx-Al2O3-MgO体系熔渣热物性演变及其对金属液滴动力学行为的影响作为研究对象，基于冶金熔体、冶金宏观动力学及冶金传输原理等理论，对含铁熔渣还原过程所涉及的氧化物组元溶解动力学及热质传输行为、熔渣物相组成与微观结构演变规律、熔渣还原过程热物性演变与调控机制、熔渣热物性演变对金属液滴动力学行为的影响、含铁熔渣还原过程的宏观动力学等科学问题进行系统研究，旨在掌握还原过程中熔渣热物性的演变规律，阐明基于熔渣组成控制而实现其热物性优化的调控机制，构建熔渣结构对其热物性的作用关系，掌握熔渣热物性对金属液滴动力学行为的作用机制。研究结果对于完善熔渣热物性参数进而实现含铁熔渣还原提铁工艺开发与过程优化具有重要学术意义和实际应用价值。

项目以铝灰还原含铁熔渣提取有价元素所涉及的CaO-SiO2-FeOx-Al2O3-MgO渣系热物性、及其对金属液滴运动行为的影响为研究对象，基于冶金熔体、冶金热力学与动力学、冶金传输原理等理论基础，开展了包括还原过程含铁熔渣高温物性演变规律、微观结构特征及其与熔渣热物性内在联系、熔渣热物性对金属熔滴运动行为的影响、含铁熔渣铝热还原过程的冶金行为等科学问题的系统研究工作。研究结果表明：还原过程中，‘FeO’、Al2O3、SiO2等组分间的耦合作用对熔渣黏度演变具有重要影响，随还原过程熔渣组成从‘FeO’成分主导向Al2O3成分主导转变，不仅导致了熔渣中硅酸盐结构单元Q0消失、同时也导致更为复杂的Q3结构单元出现，从而使得熔渣体系聚合程度增加；同时，由于熔渣O−Al−O键角分布变化较小，Al2O3依然倾向于以[Si(Al)O4]-四面体形式置入于稳定的[SiO4]-四面体结构中，熔渣聚合程度的提高制约了体系中Ca、Si、O、Al原子的传输能力，在宏观上体现为熔渣黏度的增加。无量纲毛细管数可用于描述金属铁滴群在熔渣中的碰撞与聚并行为，沉降过程中，金属铁滴之间的碰撞聚并可考虑为大铁滴追赶小铁滴的追赶碰撞模式，而其沉降模式则可看作竖直方向的单一匀速沉降运动；因此，合理调控熔渣黏度和密度可有效提高金属铁滴群的聚并与沉降效率。铝灰还原熔融改质镍渣时，金属相成分主要由Fe、Cu、Mn组成，最佳工艺条件下 Fe、Cu、Mn回收率可分别达到85.26%、92.68%、以及14.16%；还原终渣物相主要由CaMg2Al16O27、钙长石(CaAl2Si2O8)、钙铝黄长石(Ca2Al2SiO7)、镁铝尖晶石(MgAl2O4)及镁黄长石(Ca2MgSi2O7)组成，可用作水泥制备原料。