GOALI: Recycling and Purification of Silicon from Solar Grade Silicon (SoG-Si) Wastes using Electromagnetic Field

GOALI学术联络机会奖为一项利用电磁场从太阳能级硅废料中回收和提纯硅的研究提供资金。在用于生产硅片的锯切过程中，超过一半的钢锭与碳化硅颗粒、铁粉和乙二醇油一起以硅粉的形式进入废流。挑战是回收硅粉，并将其从类似大小但不受欢迎的碳化硅颗粒中分离出来。人们假设，悬浮在导电液态金属中的非导电颗粒和导电性较差的杂质相将被迫沿与所施加的电磁力相反的方向移动，从而实现分离和回收。实验工作将考察各种工艺变量的影响，理论研究将探索在电磁场下非金属颗粒从熔融硅中分离出来。这些联合活动将有助于了解回收的太阳能级硅的凝固和结晶过程，并有可能进一步提纯该材料。太阳能电池装置演示活动包括在该计划中。太阳能电池是一种具有吸引力的可再生、无污染发电技术，高纯硅是这些装置的首选材料。回收至少一部分硅废料将抵消目前每年浪费材料成本的一部分，据估计，浪费材料的成本超过50亿美元。这一新工艺有可能通过提高材料产量来降低太阳能电池的成本，并通过减少二氧化碳排放来减少对环境的影响。

This Grant Opportunity for Academic Liaison with Industry (GOALI) award provides funding for a study to recycle and purify silicon from solar grade silicon waste using an electromagnetic field. During the sawing process used to produce silicon wafers more than half of the ingot enters the waste stream as silicon powder, along with silicon carbide particles, iron powders and glycol oil. The challenge is to recover the silicon powder and separate it from the similar sized but undesirable silicon carbide particles. It has been hypothesized that the nonconductive particles and less-conductive impurity phases suspended in the conductive liquid metal will be forced to move in the opposite direction of the applied electromagnetic force, thus enabling separation and recovery. Experimental work will investigate the effect of various process variables and theoretical studies will explore the separation of non-metallic particles from molten silicon under an electromagnetic field. The combined activities will contribute to an understanding of the solidification and crystallization process of the recycled solar grade silicon with the potential to further purify the material. Solar cell device demonstration activities are included in the plan.Solar cells are an attractive technology for renewable, non-polluting power generation and high purity silicon is the material of choice for these devices. Recovery of at least some of the silicon waste would offset a portion of the present day annual cost of wasted material which is estimated to exceed $5B. This novel process has the potential to lower the cost of solar cells through improved material yield and lessen the environmental impact through reduced carbon dioxide emissions.