Fundamentals of Metallurgical Refining of Silicon

硅冶金精炼基础知识 * 利用光伏发电技术被认为是解决使用化石燃料对健康和环境影响的一个潜在办法。该计划将着眼于实现太阳能作为可持续能源的潜力的长期计划，以改善环境和人类生活。硅也许是满足太阳能材料需求的最合适的选择。将硅精炼到太阳能应用所需纯度（99.99999%）的能量和成本已被证明是实现太阳能电力成为主要能源的潜力的障碍。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。针对这一点，冶金工艺因其能够以低成本提供大生产率而受到特别关注。然而，由于硅中各种杂质的热力学性质不同，每种纯化工艺都能有效降低特定的杂质元素，因此应使用几个步骤的组合来降低总杂质水平。在硅的冶金精炼领域中的大部分研究工作一直集中在降低特定杂质浓度的工艺的开发上，而忽略了耦合各种方法的潜力。然而，越来越明显的是，降低所有杂质的浓度需要结合使用几种精炼工艺。* 通过这项发现补助金，将研究多步骤硅纯化工艺的基本原理。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，这些研究对于通过冶金技术在相对年轻的高纯硅加工领域建立知识库至关重要。提出的杂质去除的四个主题如下：*1。从合金熔体中对硅进行溶剂精炼：将使用多种金属试剂作为溶剂，以促进合金的杂质排除。* 2.硅铁合金的炉渣精炼：将使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）作为精炼硅铁合金的助熔剂 *4.硅的酸浸：使用不同的酸混合物去除主要存在于晶界的具有小偏析系数的杂质。* 该计划将在材料加工和表征领域培养3名硕士，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. **