基于电场调控熔渣结构强化硅合金熔渣精炼除硼

Thermodynamics restriction of interphase distribution coefficient and interface mass-transfer dynamics control are the common problems in the process of material separation and purification. Slag structure is the root cause to determine the physical and chemical properties of molten slag, the deep knowledge and accurate control of slag structure is the key to solve the problem for efficient removal of trace impurity elements in refining process. In this project, the electric field as a means of regulating the slag structure to optimize the reaction and mass transfer environment for interface between slag and metal, and to realize control of oxygen ion concentration by changing the degree of polymerization of the molten slag and ion distribution, which strengthens the oxidizing and reduces slag viscosity, to strengthen the boron removal from silicon alloy in slag refining process. Firstly, using the method of Raman and nuclear magnetic resonance (NMR) to analysis the mechanism of slag structure near interface under electric field; secondly, changing refining conditions, such as slag composition, temperature and electrochemical parameters, and combines with the method of slag composition and microstructure of interface, was used to reveal the mass transfer mechanism and transformation rule of B impurity in slag interface; finally, explore the existing state, activity change and distribution rule of the quadratic phase of impurities after entering into slag. These research results will provide basic data and theoretical foundation for solving the problem for removal of trace impurities in the process of slag refining.

相间分配热力学限制和界面传质动力学控制是材料分离纯化过程的共性问题。熔渣结构是决定熔渣物化性质的根本原因，熔渣结构的深度认知和精确调控是解决熔渣精炼过程中微量杂质元素高效去除的关键。本项目通过电场调控熔渣结构的手段进行渣/金相间反应传质环境优化，通过改变熔渣的聚合度以及离子分布状态实现熔渣界面氧离子浓度控制，增强其氧化性并降低熔渣粘度，达到强化硅合金熔渣精炼除硼的目的。首先通过拉曼、核磁共振等手段，解析界面处熔渣结构在电场作用下的变化机制，即氧离子与其他粒子的成键方式与存在状态、硅氧聚合体的分子结构与聚合程度等；其次，通过改变熔渣成分、温度、电化学参数等精炼条件，并结合获取渣金界面成分分布和微结构解析方法，揭示硼杂质在渣金界面的传质机制和形态转化规律；最后，探索杂质二次相进入熔渣后的存在状态、分布规律与活度变化。为解决熔渣精炼中关键微量杂质的高效去除提供基础数据和理论支撑。

相间分配热力学限制和界面传质动力学控制是材料分离纯化过程的共性问题。基于以上，通过电场调控熔渣结构的手段进行渣/金相间反应传质环境优化，通过改变熔渣的聚合度以及离子分布状态实现熔渣界面氧离子浓度控制，增强其氧化性并降低熔渣粘度，达到强化硅合金熔渣精炼除硼的目的。项目开展三方面研究内容:第一，电场对渣金界面处熔渣结构的调控机制，掌握了熔渣中不同区域尤其是两相界面处熔渣结构（氧离子与其他粒子的成键方式与存在状态、硅氧聚合体的分子结构与聚合程度等）的变化规律，并与不施加电场时的结构相比，找到电场对渣金界面处熔渣结构的调控机制。第二，熔渣结构改变时杂质硼在渣金界面传质与反应机制及形态转化规律，电场作用下，B在渣金两相的传质规律，通过改变熔渣成分、温度、电化学参数等精炼条件，并结合获取渣金界面成分分布和微结构的方法，揭示了B杂质在渣金界面的传质机制和形态转化规律。第三，熔渣物性及杂质二次相进入熔渣后的存在状态、分布规律和活度控制基本完成，探索了B在界面处反应后以二次相形式进入熔渣，其存在状态和迁移、分布规律，研究了B在渣中存在形态及结构，建立并定量关联活度变化。