转炉钢渣低温渣浴还原过程中组元的迁移规律及其动力学行为

Based on the status on appplication and research of converter slag, the present work invesitigates the slag bath reduction of molten converter slag at lower temperature using aluminium ash as reductant for the purpurse to recovery high value added iron resource. Based on thermodynamics analysis, the properties of the molten slag and the influence mechanism during reduction process are studied. Meanwhile, the migration behavior of the conponents in the molten slag as well as its dynamic behavior, and the behavior of collision, growth and setllement of the iron drops as well as the influence mechanism are also studied, and the limited step and characteristic parameters that influence the slag reduction and metal-slag seperation are determined. In addition, the materials and energy balances during the reduction process of the slag using aluminium ash are calculated, and the main factors that influence the energy consumption while the new method to treat converter slag is discussed, for the purpurse to provide theoretical basis for developing novel technology for slag treatment. The characteristics of the present work is, as two kind of the second resurces, converter slag and aluminium ash can be applied with high value added, and the physical heat carried by the molten converter slag is also well utilized, thus the outstanding resource and energy characteristics are showed. Therefore, the present work shows higher academic values. Furthermore, because of simple technology, low treatment cost and contribution to energy saving as well as energy-saving and discharge–decreasing, the research results will have good application prospects, and thus it laso have good social values.

本申报项目结合转炉钢渣利用与研究现状，以铝灰为还原剂通过渣浴还原在较低温度处理熔融转炉钢渣以高附加值回收渣中的铁资源。其中，主要在热力学研究的基础上，通过实验研究在熔渣还原过程中，熔渣性质随其组成的变化规律及其作用机制，渣中组元选择性还原过程中组元的迁移规律及其动力学行为；研究渣中铁滴碰撞、聚合长大与沉降行为及其影响机制，确定影响渣中组元还原与渣金分离动力学行为的限速环节及其特征动力学参数。在此基础上，研究利用铝灰渣浴还原熔融转炉钢渣的物料与能量平衡，确定影响这种新型工艺方法处理钢渣的能耗情况及主要影响因素，为新型转炉钢渣处理技术的开发提供理论依据。本项目特色在于可实现钢渣和铝灰两种二次资源的高附加值利用，并充分利用熔融钢渣自身携带的物理热,具有突出的资源与能源特色，具有较高的学术价值，同时由于工艺方法简单，处理成本低，促进节能减排，研究成果具有良好的应用前景，因此还具有重要的社会价值。

本申报项目结合转炉钢渣利用技术与研究现状，开展以铝灰为还原剂通过渣浴熔融还原处理熔融转炉钢渣以高附加值回收渣中的铁资源过程基础问题的研究，为新型转炉钢渣处理技术的开发提供理论依据。研究结果表明：(1)熔体中FeO起解聚作用，而Al2O3起聚合作用。反应初期，熔体的主导结构为硅酸盐结构，随着FeO含量减少，简单的硅酸盐结构转变为复杂的硅酸盐结构，且Al3+作为Si4+的替代品起增强硅酸盐结构的作用，导致硅酸盐的聚合度增强。在反应中后期，熔体的主导结构为铝酸盐结构，随着Al2O3含量增加和FeO含量进一步降低，铝酸盐结构增加，复杂的硅酸盐结构也增加，体系的聚合度显著增强，最终导致黏度由0.065Pa•s上升至0.194Pa•s。(2) Al2O3球在熔渣中溶解时，界面化学反应速率常数与边界层扩散速率常数均减少，在还原初期，受边界层扩散传质和界面反应联合控制；当还原到中后期时，限制性环节为边界层扩散传质。当熔渣碱度减少时，界面化学反应速率常数略微升高，边界层扩散速率常数明显增加，限制性环节为边界层扩散传质。(3) 随温度升高，渣中FeO还原率和还原速率均大幅度提升，其还原率均超过95%。当温度升到1600℃时，还原反应的综合速率常数显著增加，反应活化能为143.25 kJ/mol，熔渣中FeO反应的限制性环节为反应生成Al2O3在熔渣中的扩散。(4) 金属铁滴在熔渣中的沉降可分为沉降初期和沉降后期。增加渣池中下部金属铁滴的聚并，加快后期铁液的沉降，是缩短沉降时间的关键。随着熔渣黏度的增大、渣-金密度差的减小，金属铁滴的沉降效率降低，增加机械搅拌可显著提升金属铁滴的碰撞聚合和沉降效率。选择流动性好、密度低的熔渣更有利于提高金属铁滴的沉降效率，且使用转速80 rpm的十字型搅拌器更有利于实现渣金的高效分离。