Silicon Metal & Ferrosilicon Buyer Resources
Clear information for better buying decisions.
Short, specific guides to product selection and export inquiries.
Silicon Metal vs Ferrosilicon: What Buyers Need to Specify
Silicon metal and ferrosilicon both contain silicon, but they are different products for different industries. Telling a supplier “I need silicon” without the right term leads to the wrong quote. This page explains the difference and the specifications buyers must state.
1. At a glance
| Silicon Metal | Ferrosilicon (FeSi) | |
|---|---|---|
| Silicon content | 98% – 99.9% | 15% – 90% (commonly 65% / 72% / 75%) |
| Form | Lump or powder, high purity | Lump / granule, iron-silicon alloy |
| Main use | Aluminium alloys, silicones, PV, deoxidation | Steel deoxidation, inoculation, Mg reduction |
| Typical buyer | Alloy / silicone / solar plants | Steel mills, foundries, Mg producers |
| Price driver | Electricity + PV demand | Steel demand + energy |
2. When you need Silicon Metal
Specify silicon metal when silicon is the valuable element and iron is an impurity to minimise:
- Aluminium alloys – the largest consumer; 553 / 441 are common.
- Silicone polymers – 421 / 3303 for rubber, sealants, fluids.
- Photovoltaic – refined grades feed polysilicon.
- Non-ferrous deoxidation and refractory / electrode applications.
3. When you need Ferrosilicon
Specify ferrosilicon when you are making or treating steel and want silicon plus iron:
- Steel deoxidation & alloying – 75% FeSi is the standard additive.
- Inoculation / nodularising in cast iron.
- Magnesium production – 75% FeSi in the Pidgeon process.
4. What to specify in your RFQ
- For silicon metal: grade (553/441/421/3303), size (lump or powder), packing, destination.
- For ferrosilicon: Si percentage (65/72/75%), size (lump / 0-3 mm / granular), packing, any Al / C limits.
The two are not interchangeable – using ferrosilicon where silicon metal is required introduces unwanted iron; using silicon metal in steelmaking is unnecessarily expensive.
Frequently Asked Questions
What is the difference in silicon content?
Silicon metal is 98%–99.9% Si with iron as a controlled impurity. Ferrosilicon is an iron-silicon alloy, typically 15%–90% Si, with 75% and 72% the most common steelmaking grades.
Can I substitute one for the other?
No. They serve different processes. Silicon metal is for non-ferrous and chemical uses where purity matters; ferrosilicon is for steel where iron is acceptable or required.
Which is more expensive?
On a per-tonne basis silicon metal is usually the higher-priced product because of its purity and energy-intensive refining, whereas ferrosilicon is priced closer to steel-cycle economics.
Which silicon metal grade suits aluminium alloy?
553 and 441 cover most aluminium alloy and deoxidation needs; move to 421 / 3303 when lower aluminium or calcium content is required.
What ferrosilicon grade is standard for steel?
75% ferrosilicon is the most widely used deoxidizer and alloying addition in steelmaking, with 72% and 65% also common depending on the grade of steel.
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