PhD Defence Praise Tinotenda Mubaiwa - Faculty of Natural Sciences

Praise Tinotenda Mubaiwa has submitted the following academic thesis as part of the doctoral work at the Norwegian University of Science and Technology (NTNU): “Metallurgical treatment of silicon-kerf to recover solar grade silicon. He will defend his PhD thesis on May 5th at NTNU, Gløshaugen.

Public trial lecture:
Time: May 5th at 10.15
Place: S1, Sentralbygg 1, NTNU Gløshaugen
Prescribed subject: “The recovery of valuable materials from End-of-Life silicon-based PV modules; opportunities and challenges.”

Public defence of the thesis:
Time: May 5th at 13.15
Place: S1, Sentralbygg 1, NTNU Gløshaugen

You can also follow the trial lecture and defence via Zoom:

Join Zoom Meeting:
https://NTNU.zoom.us/j/97485765690?pwd=GCcn0XhSGZ1uMAbTJqBZJAc2QeKChb.1

The Faculty of Natural Science has appointed the following Assessment Committee to assess the thesis:
• Associate Professor Leili Tafaghodi, McMaster University, Hamilton, Ontario, Canada
• Dr. Lars K. Jakobsson, Elkem, Kristiansand, Norway,
• Professor Merete Tangstad, Department of Materials Science and Engineering, NTNU

Professor Merete Tangstad, NTNU, Norway has been appointed Administrator of the Committee. The Committee recommends that the thesis is worthy of being publicly defended for the PhD degree.

Supervisors
The doctoral work has been carried out at the Department of Materials Science and Engineering, where Professor Jafar Safarian has been the candidates’ supervisor and Professor Przemyslaw B. Kowalczuk, Department of Geosciences, NTNU have been the candidates’ co-supervisor.

Summary
The recent global climate challenges have necessitated the current conversations around sustainability and clean, renewable energy. Solar energy has emerged among the frontrunners in this regard, and its utilization has seen exponential growth over past decades. The process of obtaining solar energy begins with the carbothermic reduction of quartz, all the way to manufacturing solar panels. During this process a significant amount of material is lost, particularly during the cutting process to produce wafers. This material(sawdust) that is produced is known as silicon kerf. Silicon kerf is present in millions of tons and as such is a very good secondary source of photovoltaic silicon. Although this silicon powder is produced from very pure material (≥ 99.9999 % purity), impurities are introduced during the cutting process which make its direct recirculation unsuitable. However, this presents both challenges and opportunities for the scientific and photovoltaic community to recycle it back
into the value chain or at the very least make a useful product out of it. This study focused on the application of metallurgical processes to recycle silicon kerf powder from
industrial waste. Several processes were applied, and they revealed that kerf is a complex material, which requires careful handling, processing and characterization. A combination of low and high temperature processes proved to be effective in upgrading this industrial waste to valuable products, and detailed conditions under which this can be attained were proposed. Overall, the recycling of silicon kerf waste presents endless opportunities for green energy generation and related applications, some of which include but are not limited to, solar photovoltaic silicon, lithium-ion batteries among others. 

The work has been founded by FME SUSOLTECH (The Research Center for Sustainable Solar Cell Technology)