工业硅炉外精炼提纯过程中杂质演变行为研究进展

Research Progress of Impurity Evolution Behavior in the Process of Industrial Silicon Secondary Refining Purification

工业硅是光伏硅产业链中不可或缺的重要原材料,探索工业硅炉外精炼过程中杂质的演变行为对于杂质的深度去除具有重要意义.本文综述了在工业硅吹气精炼、造渣精炼和联合精炼过程中杂质的反应热力学与动力学行为以及凝固过程杂质相的析出特性与赋存行为,综述了炉外精炼对工业硅中杂质去除的效果.研究表明,炉外精炼去除工业硅中的杂质B、P是非常有效的方法,杂质含量可达到太阳能级硅的水平.在工业硅铸模凝固过程中,杂质含量及成分、凝固速度和精炼温度等因素会影响工业硅中杂质相的析出行为.此外,开展炉外精炼过程中Fe、Ti等杂质的去除研究以及建立凝固过程中杂质相析出特性与去除率之间的相互作用关系具有十分重要的意义,也是推动炉外精炼技术水平提升的关键因素.

Industrial silicon is an indispensable raw material in the photovoltaic silicon industry chain.It is of great significance to explore the evolution behavior of impurities during the refining process of industrial silicon for the deep removal of impurities.This paper reviews the thermodynamic and kinetic behavior of impurities in the process of blowing refining,slagging refining,and combined refining of industrial silicon,as well as the precipitation characteristics and occurrence behavior of impurity phases in the solidification process.The effect of secondary refining on removing impurities in industrial silicon is reviewed.Studies have shown that it is a very effective method to remove impurities B and P in industrial silicon by secondary refining,and the impurity content can reach the level of solar-grade silicon.In the solidification process of industrial silicon mold,the impurity content and composition,solidification rate,and refining temperature will affect the precipitation behavior of the impurity phase in industrial silicon.In addition,it is of great significance to carry out research on the removal of impurities such as Fe and Ti during the refining process and to establish the interaction between the precipitation characteristics of impurity phases and the removal rate during the solidification process,which is also a key factor to promote the improvement of the refining technology level.