Introduction
Silicon metal is a grayish metalloid which is a very important raw material used in various industries. Silicon constitutes nearly 27.7% of the Earth’s crust by mass, making it the second most abundant element. It rarely occurs naturally as a pure element and is often found combined with oxygen in rocks and soils.
Properties of Silicon Metal
Silicon metal has unique physical and chemical properties which make it suitable for various industrial applications:
It is a brittle, hard metalloid with cubic crystalline structure. Its melting point is very high at 1414°C which makes it thermally very stable.
Chemically, it is quite reactive and doesn’t occur freely in nature. It forms a protective oxide layer when exposed to oxygen and moisture which prevents further oxidation.
Being a semiconductor, its electrical conductivity increases with rising temperature. This property is utilized in making semiconductor devices, solar cells etc.
Silicon is relatively non-toxic as compared to other heavy metals. However, inhalation of its dust can cause lung damage over long term exposure.
Its high chemical reactivity makes it suitable as a reducing agent. Finely powdered silicon can be used as an additive in pyrotechnic compositions.
Production of Silicon Metal
Silicon metal is produced through carbothermic reduction of high purity quartzite or sand in electric arc furnaces. Some of the key steps involved are:
Purification of quartz: The silica sand/quartzite ore is processed to obtain at least 99% pure silica which is used as the feedstock.
Reduction in furnace: The purified Silicon Metal is mixed with carbon reductants like coal or wood chips and fed into submerged electric arc furnaces. The mixture is melted and silicon separates from oxygen.
Refining: The impurities in the crude silicon are removed through processes like distillation or slags. The end product obtained usually contains >99% pure silicon.
Alloying: Pure silicon is sometimes alloyed with other metals like aluminium, copper etc. to obtain alloys with enhanced properties.
Applications of Silicon Metal
Due to its unique properties, silicon finds wide usage mainly in four major industries:
Aluminium Industry
Silicon is added to molten aluminium as a deoxidizing and alloying element. This improves the fluidity, castability and mechanical properties of the final alloy.
Ferrosilicon and silicomanganese are used in steel making for similar purposes.
Chemical Industry
Silicon dioxide or silica obtained from silicon processing is used in many applications such as manufacturing of glass, ceramics, refractories, abrasives etc.
Semiconductor Industry
Silicon wafers form the base material for semiconductor devices, integrated circuits and microchips used in computers and electronics. Over 90% of the total produced silicon goes into this industry.
Solar Photovoltaic Industry
Silicon in the form of mono or polycrystalline wafers is used as the active material in most commercial solar cells to convert sunlight into electricity.
Future Prospects
With the continuous growth in sectors like green energy, electronics and lightweight aluminium alloys, the demand for high purity silicon metal is expected to rise significantly in the coming decades. Some areas being focused on are:
Development of more energy efficient and economic production methods.
Use of waste materials from other industries in silicon production to improve sustainability.
Production of silicon alloys/compounds for specialized applications in batteries, coatings etc.
Use in emerging technologies involving semiconductors like flexible electronics, 5G communications etc.
Silicon metal occupies a very important place in the modern materials landscape due to its versatility. With varied uses across major industrial sectors, it will continue playing a pivotal role in economic and technological development worldwide in the future as well. Research on new applications, improved production processes and effective recycling will further augment its strategic position.
*Note:
1. Source: Coherent Market Insights, Public sources, Desk research
2. We have leveraged AI tools to mine information and compile it.