What is Ferro Silicon and Why Do We Use Them?

Ferrosilicon (FeSi) is an alloy of iron and silicon with a very variable silicon content between 10% and 90%. It is used as a so-called master alloy in steel production, which is added in small amounts in order to adjust the properties of the melt, the cooling process and the finished product.

The main advantage of FeSi is its deoxidizing effect (i. e. it reduces metals from their oxides), but it also helps to prevent the loss of carbon. Furthermore, ferrosilicon is used in electrode coatings and in the production of silicon, hydrogen and magnesium.

Ferrosilicon is produced either in a blast furnace or electric arc furnace by the reduction of quartz sand (SiO2) with coke in the presence of iron. The melt is poured out of the furnace and solidifies in the form of a flat sheet.

After cooling, this sheet is crushed by appropriate machinery and then further processed in a crusher. The resulting particle size distribution ranges from fine dust-like particles to cm-sized chunks. The FeSi is sifted into different size grades for further use.

Microtrac's CAMSIZER series is ideally suited for the particle size distribution analysis of ferrosilicon and other granular metals. Microtrac analyzers are used both for quality control industrial applications as well as research purposes. 

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The CAMSIZER P4 dynamic image analyzer determines particle size and shape in a range from 20 μm to 30 mm and is therefore ideally suited for the routine analysis of ferrosilicon. The particles under investigation are conveyed by a vibratory chute into the measurement zone where they are passing a planar light source in free fall. The resulting shadow projections are captured by a camera system and evaluated in real time. The CAMSIZER P4 features the unique Dual-Camera Technology. One camera (ZOOM) detects fine particles with great accuracy and a second camera (BASIC) with lower magnification, but larger field of view detects large particle simultaneously. This is an invaluable advantage because the CAMSIZER P4 can analyze all particles within one sample without any hardware adjustments and without losing accuracy for either very large or very fine particles. Thanks to the two cameras, ideal measurement conditions can be established for the entire size range, the analysis is therefore extremely convenient and accurate.

The huge advantage of this arrangement is the vast amount of sample that can be processed in a very short analysis time of only a few minutes. The CAMSIZER P4 is maintenance-free and therefore offers a faster and more reliable alternative to traditional sieve analysis. Thanks to its robust design, the CAMSIZER P4 unsusceptible to vibration and dust. The instrument can therefore operate in an industrial plant as well as in a laboratory environment.

In this example we present the results of the particle size analysis of different grades of ferrosilicon (Fig. 4). All measurements have been made with a CAMSIZER P4 image analyzer. The finest sample is in a size range from 0,2 mm to 0,7 mm. The largest sample contains particles up to 30 mm, which is the upper size limit of the CAMSIZER P4. Repeatability of the results is a key factor to evaluate the reliability of a measurement device. The CAMSIZER P4 can detect and analyze hundreds of thousands or even millions of particles within a few minutes. The size distribution is therefore based on a huge dataset, giving the result a high confidence level and leading to great repeatability (Fig. 5).

Particle characterization with Dynamic Image Analysis offers a wide range of different parameters that can be determined for every particle: different size definitions for length, width and equal area diameter are available, as well as various shape parameters such as aspect ratio, roundness, convexity and many more. If comparability to traditional sieve analyse is required, the size definition &#;particle width&#; is used to calculate the distribution. Sieving allows width measurement as well since the particles pass the apertures with the smallest projection surface (Fig. 6). Comparability of CAMSIZER P4 results and sieve analysis can easily be established (Fig. 7).

How is ferrosilicon made?

Ferrosilicon, commonly abbreviated FeSi, is an iron&#;silicon alloy that also contains smaller proportions of other elements. The most popular grade of ferrosilicon contains 75 wt% silicon (&#;FeSi75&#;), but the amount can range from 15&#;90 wt% depending on the application.

The highest-quality ferrosilicon is made in an electric arc furnace by reducing silica with coke in the presence of iron (usually derived steel scrap or iron ore). The ferrosilicon usually takes the form of shiny, metallic-grey lumps, but is also available as pre-formed briquettes.

The role of ferrosilicon in steelmaking

In steelmaking, ferrosilicon is used for:

• Product performance &#; Ferrosilicon is a convenient way of adding silicon as an alloying element, to improve various properties of the final steel.
• Slag reduction &#; In the manufacture of stainless steels, the presence of silicon reduces chromium oxides in the melt, improving recovery of metallic chromium.
• Deoxidation &#; Ferrosilicon provides quick-acting removal of oxygen from the melt, so avoiding the presence of inclusion-forming oxides and avoiding loss of desirable elements.
• Fuel &#; Some steel mills add ferrosilicon to the melt so that it can be burnt off to get heat into the furnace, and so reduce energy costs.

What are the types of ferrosilicon?

Ferrosilicon is often categorized according to the levels of various minor components, depending on the application requirements. These categories include:

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• Low-carbon ferrosilicon and ultra-low-carbon ferrosilicon &#; Used to avoid re-introducing carbon during the manufacture of stainless steel and electrical steel.
• Low-titanium (high-purity) ferrosilicon &#; Used to avoid TiN and TiC inclusions in electrical steel and some special steels.
• Low-aluminium ferrosilicon &#; Used to avoid the formation of hard Al2O3 and Al2O3&#;CaO inclusions in a range of steel types.
• Special ferrosilicon &#; A general term that covers a range of tailor-made products containing other alloying elements.

Ferrosilicon from Elkem

Ferrosilicon for all steel applications

As well as providing STD 75, STD 50 ferrosilicon and ferrosilicon briquettes, we offer a range of premium ferrosilicon compositions that provide optimum results for high-performance steel grades. We&#;d be delighted to talk about your requirements and find the best product for you.

• Electrical steel &#; Our ELEKSIL&#; ferrosilicon is available in a range of grades tailored to the needs of electrical steel manufacture, with inherently low levels of carbon and titanium, and precisely-defined proportions of minor elements.
• Stainless steel &#; Our STAINSIL&#; ferrosilicon portfolio include low-carbon and ultra-low-carbon grades.
• Special steel &#; Our PURISIL&#; ferrosilicon products provide reliably low levels of trace elements such as aluminium, making them perfect for manufacturing a range of special steels.

Clean, consistent ferrosilicon

Ferrosilicon from Elkem is among the cleanest available anywhere, helping you to meet the demands of exacting steel compositions while streamlining production and reducing energy costs.

Thanks to our strong quality management, our ferrosilicon is highly consistent in purity and size grading from batch to batch. This means that you can eliminate worries about shifting performance, unpredictable dissolution times, or variable downstream alloying requirements.

Unbeatable expert support

In contrast to other suppliers, we take care to ensure that the ferrosilicon we provide will give you the best possible results.

So whatever you want to ask us about &#; from the optimum way of introducing our ferrosilicon into the melt, to trialling a new grade in your steel mill &#; then we&#;re ready to listen to you.

Timely and reliable delivery

With a global presence and regional knowledge, we can supply ferrosilicon to all major steel-producing areas, as quickly as you need it. So whatever grade of ferrosilicon you need, if you need it delivered urgently, then we won&#;t let you down.

The Elkem advantage

Sustainability in mind

The production of silicon ferroalloys uses carbon to remove the oxygen from silica, releasing carbon dioxide in the process. The high temperatures needed in our furnaces also consume a lot of energy. But we&#;re committed to doing what we can to reduce this CO&#; footprint, by increasing the proportion of renewably-sourced carbon we use, moving to renewable power sources, or embarking on an ambitious project for carbon capture and storage. You can read more about our plans in our global climate roadmap.

With you at every step

We&#;re more than just a manufacturer &#; buying ferrosilicon from us is a collaboration. We&#;ll listen carefully to your product requirements, work out the ferrosilicon specification that will deliver maximum product quality and cost-effectiveness for you, and offer expert guidance and insight at every stage of the production process.

The company is the world’s best High Purity Silica Sand supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.