Grants and Contributions:

Grant or Award spanning more than one fiscal year. (2017-2018 to 2022-2023)

Fundamentals of Metallurgical Refining of Silicon
Utilizing photovoltaic technologies for power generation has been considered as a potential solution to the health and environmental impacts caused by the use of fossil fuels. This program will target the long term plan of realizing the potential of solar energy as a sustainable source, towards improvement of the environment and human life.
Silicon is perhaps the most suitable choice for fulfilling the demand for solar materials. The energy and cost of refining silicon to the required purity for solar applications (99.99999%) has proven to be an obstacle in realizing the potential of solar electricity to become a major energy source. This is mainly attributed to the lack of a dedicated process for producing solar grade silicon (SoG-Si) at an acceptable cost and high production rate.
In response to this, metallurgical processes have received particular attention because of their ability to deliver large production rates at low cost. However due to the different thermodynamic properties of various impurities in silicon, each purification process is effective for lowering specific impurity element(s), as a result a combination of several steps should be used to reduce the overall impurity level.
Most of the research work in the field of metallurgical refining of silicon has been focused on the development of processes to reduce the concentration of a specific impurity, while the potential for coupling various methods has been overlooked. However, it is becoming clear that reducing the concentration of all impurities requires employing combination of several refining processes.
Through this Discovery Grant, the fundamentals of a multi-step silicon purification process will be studied. This research is essential for developing an energy efficient technology for producing silicon suitable for solar applications. In addition, these studies are critical in creating a knowledge base in the relatively young field of high purity silicon processing by metallurgical techniques.
The four topics proposed for impurity removal are as follows:
1. Solvent refining of Si from an alloy melt: Multiple metallic agents will be used as solvents to promote impurity rejection to the alloy.
2. Slag refining of Si-Fe alloys: Mixture of various oxides will be employed to preferentially oxidize impurities in the slag phase.
3. Utilization of red mud (an abundant industrial waste material) as a fluxing agent for refining Si-Fe alloys
4. Acid Leaching of Si: Employing different acid mixtures to remove impurities with small segregation coefficient that mostly exist at grain boundaries.
This program will train 3 MASc, 1 PhD and 2 undergraduates in the fields of materials processing and characterization and prepare them for their future roles as engineers, consultants and researchers in both industry and academia.