Fundamentals of Metallurgical Refining of Silicon

冶金精炼硅的基础*利用光伏发电技术被认为是解决使用化石燃料造成的健康和环境影响的潜在解决方案。该计划将着眼于实现太阳能作为可持续能源的潜力，改善环境和人类生活的长期计划。*硅可能是满足对太阳能材料需求的最合适的选择。事实证明，将硅提炼到太阳能应用所需的纯度(99.99999%)的能源和成本是实现太阳能发电成为主要能源潜力的障碍。这主要是由于缺乏以可接受的成本和高生产率生产太阳能级硅(SOG-Si)的专用工艺。*针对这一问题，冶金工艺特别受到关注，因为它们能够以低成本提供高生产率。然而，由于硅中各种杂质的热力学性质不同，每一种提纯工艺都能有效地降低特定杂质元素(S)，因此应结合几个步骤来降低总体杂质水平。*硅冶金精炼领域的大部分研究工作集中在开发降低特定杂质浓度的工艺上，而忽略了各种方法耦合的可能性。然而，越来越明显的是，降低所有杂质的浓度需要使用几个精炼过程的组合。*通过这项发现基金，将研究多步骤硅提纯工艺的基本原理。这项研究对于开发一种生产适用于太阳能应用的硅的节能技术至关重要。此外,这些研究对于在相对年轻的冶金技术处理高纯硅领域建立知识库是至关重要的。*提出的四个去除杂质的主题如下：*1.从合金熔体中进行硅的溶剂精炼：将使用多种金属试剂作为溶剂以促进对合金的杂质排斥。*2.硅铁合金的熔炼：将采用各种氧化物的混合物优先氧化渣相中的杂质。*3.利用赤泥(一种丰富的工业废料)作为熔剂进行精炼4.硅的酸浸：采用不同的酸混合物，去除主要存在于晶界的分凝系数较小的杂质。*该项目将在材料加工和表征领域培训3名MASC、1名博士和2名本科生，并为他们未来在工业和学术界担任工程师、顾问和研究人员做好准备。**

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. **