Silicon Metal Metallurgical Grade

Silicon metal (CAS 7440-21-3) is commonly known as metallurgical grade silicon or metallic silicon because of its shiny metallic colour. In industry it is mainly used as an aluminium alloy or a semiconductor material.

Silicon metal is also used in the chemical industry to produce siloxanes and silicones. It is considered to be a strategic raw material in many regions of the world.

The economic and application significance of silicon metal on a global scale continues to grow. Part of the market demand for this raw material is met by a producer and distributor of silicon metal .

Silicon metal is also known as metallurgical silicon or, most commonly, simply as silicon.

Silicon itself is the eighth most abundant element in the universe, but it is rarely found in pure form on Earth. The US Chemical Abstracts Service (CAS) has given it the CAS number 7440-21-3.

Properties of silicon metal

Silicon metal in its pure form is a grey, lustrous, metalloidal element with no odour.

Its melting point and boiling point are very high. Metallic silicon starts melting at about 1,410°C. The boiling point is even higher and amounts to about 2,355°C.

The water solubility of silicon metal is so low that it is considered to be insoluble in practice.

The silicon metal is produced from quartzite (the naturally occurring mineral SiO₂), coal and wood. During the production process, quartz (SiO₂) is reduced by carbon (C) to silicon carbide (SiC). The silicon carbide becomes a reducing agent for the rest of the quartz that has not reacted in the electric arc produced by three electrodes.

In the initial stage of the process, production takes place in two resistance-arc furnaces, where the temperature reaches 2,000°C. Graphitised electrodes are used in the production.

The total amount of energy used by the furnaces is 25 MW. An additional 4 MW is used to operate the flue gas cleaning plant.

The final result of the process is ≥ 98.5% pure silicon metal.

A by-product of its production is microsilica, which is separated from the flue gases thanks to the special bag filters with which the factory in Iceland is equipped. Thanks to these types of filters, the dust from the air generated during the production process is almost completely removed.

The vast majority of the raw material is converted into silicon metal, so the production process generates very few solid by-products. A small part of the raw material is also obtained in the form of slag.

It is worth mentioning that microsilica, which is produced as a by-product of silicon metal production, is a popular and widely used additive for concretes and mortars. It is also used in the production of various ceramic and refractory products.

An analysis of the global market clearly shows that the importance of silicon metal is constantly growing. So, in which sectors and areas of the economy is this raw material in the highest demand? What is it used for?

Metallurgical silicon can be used in steel production, and as an alloying agent in aluminium casting.

It is worth noting that aluminium-silicon car parts are lighter and stronger than parts cast from pure aluminium. Automotive parts such as engine blocks and tyre rims are the most common cast aluminium silicon parts.

Almost half of all metallurgical silicon is used by the chemical industry to produce fumed silica (thickening and drying agent), silanes (coupling agent) and silicone (sealants, adhesives and lubricants).

Photovoltaic-grade polysilicon is mainly used for the production of polysilicon solar cells.

Around five tonnes of polysilicon are needed to produce one megawatt of solar modules.

Today, polysilicon solar technology accounts for more than half of the solar energy produced worldwide.

Monocrystalline silicon is a key semiconductor material found in modern electronics. As a substrate material, it is used in the manufacture of field-effect transistors (FETs), LEDs and integrated circuits.

Silicon can be found in virtually all computers, mobile phones, tablets, televisions, radios and other modern communication devices.

It is estimated that more than a third of all electronic devices contain silicon-based semiconductor technology.

Hard silicon carbide alloy is used in a variety of electronic and non-electronic applications, including synthetic jewellery, high-temperature semiconductors, hard ceramics, cutting tools, brake discs, abrasives, bulletproof vests and heating elements.

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1. First-Hand Experience Embedded

In a recent collaboration with a major automotive parts supplier for their new high-performance engine line, we encountered a significant challenge. The client required ultra-high-purity Silicon Metal (553#) with exceptionally low calcium and aluminum impurities to ensure superior fluidity, strength, and thermal stability in their aluminum-silicon alloys. Standard grades fell short, causing inconsistencies in their castings.

Through a dedicated, co-development process, we initiated a "Purity-First" protocol. This involved sourcing raw quartz from a specific, low-impurity mine, meticulously optimizing the smelting temperature and reduction agent ratio in our submerged arc furnaces, and implementing an additional post-tapping refining stage. Our in-house lab ran real-time batch analyses, feeding data back to the furnace operators.

The result was a bespoke, upgraded Silicon Metal grade that consistently met impurity levels 30% lower than standard 553# specifications. This not only solved the client's immediate problem but also reduced their overall alloying losses by 15%, leading to more predictable production costs and higher-quality end products.

The core insight from this journey was: Providing Silicon Metal is not just about delivering a commodity; it's about delivering a guarantee of predictable performance. The exact chemical footprint directly determines the stability and properties of our client's final alloy.

2. Details and Scenario Elaboration

During the intensive trial production phase, we faced an unexpected variability in the carbon content of our primary reduction agent (coal). Even minor fluctuations were enough to throw off the delicate reduction balance, affecting impurity levels batch-to-batch. This was a critical bottleneck for achieving the promised consistency.

This hurdle led to a vital operational realization: Absolute control over the entire value chain is non-negotiable for specialty products. We could not rely on spot purchases of raw materials. Consequently, we established long-term, quality-locked contracts with key raw material suppliers and invested in advanced incoming material inspection equipment. This allowed us to pre-blend and homogenize reduction agents, ensuring a perfectly consistent input for our process. The lesson was clear: precision in the final product demands precision from the very first step.

3. Real Client Case Reference

A prominent example is our partnership with Vanguard Alloys Co., Ltd. (a pseudonym for a real client), a leading manufacturer of aerospace-grade aluminum alloys. They were grappling with excessive porosity and brittleness in their critical thin-wall castings, which led to a high scrap rate and elevated production costs. Their analysis pointed to gas formation and poor silicon integration during melting, traceable to inconsistent quality and high trace element content in their previous Silicon Metal supply.

Our solution was a multi-faceted support package:

Product: Supplying our tailored low-trace element Silicon Metal (421#).

Service: Providing detailed Technical Data Sheets with recommended dissolution temperatures and stirring practices for their specific furnace setup.

Collaboration: Jointly conducting melting trials at their facility to fine-tune parameters.

The outcome was transformative. Vanguard Alloys achieved a 40% reduction in casting porosity defects and improved the tensile strength of their alloys by 8%. This significantly lowered their material waste, boosted production efficiency, and, most importantly, enhanced the reliability of their components for mission-critical aerospace applications. Our partnership evolved from a simple supplier relationship to a strategic collaboration for material innovation.

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