Ferrosilicon (FeSi) - Industrial-Grade Ferroalloy for Steelmaking, Foundry & Magnesium Smelting
Core Value Propositions
Multi-Grade Availability - FeSi75, FeSi72, FeSi70, FeSi65, and low-aluminum / high-purity specialty grades to match your process requirements
Certified Quality, Every Batch - Full Mill Test Certificate (MTC) provided per shipment; compliant with GB/T 2272-2020, ASTM A100, and ISO 5445
Custom Sizing & Packaging - Granule sizes from 0-1mm to 50-100mm, with 1-1.25MT bulk bags or 25kg small bags; moisture-proof export packaging
Consistent Supply for Bulk Procurement - Reliable ferrosilicon sourcing for steel mills, foundries, and magnesium producers worldwide
Technical Support for Specification Matching - Our team assists with grade selection, particle size optimization, and custom chemical composition
What Is Ferrosilicon?
Ferrosilicon (FeSi) is an iron-silicon alloy produced by the reduction of silica with coke in the presence of iron in a submerged arc furnace. It is one of the most widely used ferroalloys in the metallurgical industry. The silicon content in commercial ferrosilicon typically ranges from 65% to 75% by weight, with the balance primarily iron and controlled levels of carbon, aluminum, phosphorus, and sulfur.
Ferrosilicon serves as a critical deoxidizer and alloying agent in steel production, an inoculant in cast iron manufacturing, and a reducing agent in the Pidgeon process for magnesium metal extraction. Its high affinity for oxygen makes it indispensable in primary steelmaking, while its controlled silicon release properties support graphitization in gray and ductile iron casting.
The alloy is supplied in lump, granular, and powder forms, with particle size distributions tailored to specific metallurgical applications. Standard production grades include FeSi75 (Si ≥ 75%), FeSi72 (Si ≥ 72%), FeSi70 (Si ≥ 70%), and FeSi65 (Si ≥ 65%), with custom low-aluminum and high-purity variants available for specialized processes.
Technical Specifications
Chemical Composition by Grade
|
Grade |
Si (min) |
C (max) |
Al (max) |
P (max) |
S (max) |
Fe (balance) |
|---|---|---|---|---|---|---|
|
FeSi75 |
≥ 75.0% |
≤ 0.20% |
≤ 2.0% |
≤ 0.04% |
≤ 0.02% |
Remainder |
|
FeSi72 |
≥ 72.0% |
≤ 0.20% |
≤ 2.0% |
≤ 0.04% |
≤ 0.02% |
Remainder |
|
FeSi70 |
≥ 70.0% |
≤ 0.20% |
≤ 2.0% |
≤ 0.04% |
≤ 0.02% |
Remainder |
|
FeSi65 |
≥ 65.0% |
≤ 0.20% |
≤ 2.0% |
≤ 0.04% |
≤ 0.02% |
Remainder |
Notes:
Custom low-aluminum grades (Al ≤ 1.0% or lower) available upon request
Other trace elements controlled per application requirements
Chemical composition certified via Mill Test Certificate (MTC) for every batch
Physical Properties
|
Property |
Specification |
|---|---|
|
Appearance |
Silver-gray metallic lumps, granules, or powder |
|
Density |
3.0 – 3.3 g/cm³ |
|
Melting Point |
1,250 – 1,380 °C (varies with silicon content) |
|
Particle Size (Standard) |
0-1mm, 1-3mm, 3-10mm, 10-50mm, 50-100mm |
|
Custom Sizing |
Available per customer specification |
|
Storage Stability |
3 – 5 years under proper conditions |
Storage Requirements: Store in a dry, well-ventilated warehouse on raised pallets or platforms to prevent ground moisture absorption. Ferrosilicon is hygroscopic in powder form; sealed, moisture-proof packaging is essential for export shipments.
Major Applications
Steelmaking - Deoxidation & Alloying
Ferrosilicon is a primary deoxidizer in steel production. Its high affinity for oxygen enables efficient removal of dissolved oxygen from molten steel, preventing gas porosity and improving mechanical properties. As an alloying agent, it increases steel strength, elasticity, and acid resistance. FeSi75 and FeSi72 are the most commonly specified grades for steelmaking applications.
Foundry - Inoculant for Cast Iron
In gray iron and ductile (nodular) iron casting, ferrosilicon functions as an inoculant to promote graphite formation and control microstructure. Proper inoculation improves casting machinability, reduces chill depth, and enhances mechanical strength. FeSi75 is frequently used for inoculation due to its high silicon content and controlled trace element profile.
Magnesium Smelting - Pidgeon Process Reductant
Ferrosilicon serves as the reducing agent in the Pidgeon process for magnesium metal production. Approximately 1.2 tonnes of ferrosilicon are consumed per tonne of magnesium produced. High-purity FeSi75 with low aluminum content is preferred for this application to maximize reduction efficiency and minimize slag contamination.
Welding Materials
Ferrosilicon powder is used as a deoxidizing and alloying component in welding electrode coatings and submerged arc welding fluxes. It stabilizes the weld pool, improves bead appearance, and enhances deposited metal properties.
Mineral Processing - Heavy Medium Separation
Fine ferrosilicon powder (typically 65-72% Si, sized to specific density requirements) is used as a dense medium in coal and mineral washing operations, where its controlled density enables efficient gravity separation.
Ferrosilicon vs Other Deoxidizers / Alloys
Procurement professionals frequently evaluate ferrosilicon against alternative deoxidizers and ferroalloys. The following comparisons outline the key technical and economic distinctions to support informed sourcing decisions.
1. Ferrosilicon vs Calcium Silicon (CaSi)
Core difference: CaSi adds calcium for deep desulfurization and inclusion modification, whereas ferrosilicon is a cost-efficient general-purpose deoxidizer with no calcium benefit.
|
Dimension |
Ferrosilicon (FeSi) |
Calcium Silicon (CaSi) |
|---|---|---|
|
Chemical Composition |
65-75% Si, balance Fe; trace Ca, Al |
28-35% Ca, 55-65% Si, balance Fe |
|
Primary Function |
General deoxidation and silicon alloying |
Deep deoxidation + desulfurization + inclusion shape control |
|
Applicable Steel Grades |
Plain carbon steel, structural steel, cast iron |
Linepipe steel, tire cord steel, bearing steel (ultra-clean grades) |
|
Cost Position |
Typically lower cost per unit silicon |
Higher unit cost due to calcium content and cored-wire packaging |
|
Advantages |
Lower cost; versatile across grades; stable supply |
Superior inclusion control; improves castability of high-grade steels |
|
Limitations |
No calcium effect; less effective for ultra-low sulfur targets |
Higher cost; calcium volatility requires controlled injection |
2. Ferrosilicon vs Ferromanganese (FeMn)
Core difference: FeSi and FeMn serve complementary roles - FeSi deoxidizes and adds silicon, while FeMn primarily alloys manganese for strength and hardenability.
|
Dimension |
Ferrosilicon (FeSi) |
Ferromanganese (FeMn) |
|---|---|---|
|
Chemical Composition |
65-75% Si, balance Fe |
65-82% Mn, 6-8% C (HC), 1.5% C (MC), 0.1-0.7% C (LC) |
|
Primary Function |
Deoxidation + silicon alloying |
Manganese alloying + secondary deoxidation |
|
Applicable Steel Grades |
Most carbon and low-alloy steels |
Structural steel, rail steel, tool steel requiring Mn > 1% |
|
Cost Position |
Lower than FeMn on a per-tonne basis in most markets |
Higher; manganese ore pricing drives volatility |
|
Advantages |
Stronger deoxidizer than Mn; improves fluidity; acid resistance |
Essential for strength/toughness; widens austenite phase field |
|
Limitations |
Does not contribute manganese |
Weaker deoxidizer than Si; carbon carryover in HC grades |
Combined Use Note: FeSi and FeMn are frequently used together in steelmaking. Silicomanganese (SiMn) offers a blended alternative when both Si and Mn are required simultaneously, reducing the number of additions.
3. Ferrosilicon vs Silicon Metal (Metallurgical Grade Silicon)
Core difference: Silicon metal has significantly higher Si purity (98-99%+) but at a substantially higher cost, making it suitable for chemical and solar applications rather than conventional steelmaking.
|
Dimension |
Ferrosilicon (FeSi) |
Silicon Metal (Met. Grade) |
|---|---|---|
|
Chemical Composition |
65-75% Si, 20-25% Fe, trace Al, Ca |
98-99%+ Si, <1% Fe, <0.5% Al, <0.1% Ca |
|
Primary Function |
Steel deoxidation and alloying; foundry inoculation |
Aluminum alloying; silicone production; solar-grade polysilicon feedstock |
|
Applicable Scenarios |
Steelmaking, foundry, magnesium smelting |
Chemical industry (silicones), aluminum brazing, electronics-grade purification |
|
Cost Position |
Significantly lower; iron dilution reduces unit silicon cost |
3-5x higher per unit silicon; energy-intensive carbothermic reduction |
|
Advantages |
Cost-effective for steel; iron content is neutral or beneficial |
Ultra-high purity; essential for chemical and semiconductor supply chains |
|
Limitations |
Lower Si content requires larger addition quantities |
Prohibitively expensive for bulk steel deoxidation; over-specification |
4. Ferrosilicon vs Aluminum-based Deoxidizers
Core difference: Aluminum is a stronger deoxidizer than silicon but generates alumina inclusions that require calcium treatment; ferrosilicon offers a balanced deoxidation profile with fewer inclusion risks.
|
Dimension |
Ferrosilicon (FeSi) |
Aluminum-based Deoxidizers |
|---|---|---|
|
Chemical Composition |
65-75% Si, balance Fe |
Pure Al (99.7%+), FeAl, or Al-wire/cored wire |
|
Deoxidation Strength |
Moderate; Si-O equilibrium at higher oxygen levels |
Stronger; achieves lower dissolved oxygen |
|
Inclusion Type |
Generates silica-based inclusions (softer, less harmful) |
Generates Al$$_$$O$$_$$ inclusions (hard, clogging risk) |
|
Applicable Steel Grades |
General structural, boiler, ship plate grades |
IF steel, drawing grades requiring ultra-low oxygen |
|
Cost Position |
Generally lower; stable ferroalloy pricing |
Aluminum LME price volatility; premium for wire injection |
|
Advantages |
Fewer inclusion issues; no clogging; predictable performance |
Deeper deoxidation; faster reaction kinetics |
|
Limitations |
Higher residual oxygen than Al deoxidation |
Alumina control requires Ca treatment; nozzle clogging risk |
5. Ferrosilicon vs Ferrosilicon Magnesium (FeSiMg)
Core difference: FeSiMg is a specialized nodularizer for ductile iron production containing 5-10% Mg, whereas standard ferrosilicon contains negligible magnesium and is used for inoculation only.
|
Dimension |
Ferrosilicon (FeSi) |
Ferrosilicon Magnesium (FeSiMg) |
|---|---|---|
|
Chemical Composition |
65-75% Si, balance Fe; <0.05% Mg |
44-50% Si, 5-10% Mg, 0.5-1.5% RE (optional), balance Fe |
|
Primary Function |
Inoculation (promotes graphite flakes in gray iron) |
Nodularization (spheroidizes graphite in ductile iron) |
|
Applicable Foundry Processes |
Gray iron inoculation; pre-conditioning |
Ductile (nodular) iron production; compacted graphite iron |
|
Cost Position |
Lower base cost |
Higher; magnesium content and specialized production |
|
Advantages |
Cost-effective inoculation; wide availability |
Essential for ductile iron; controlled Mg recovery |
|
Limitations |
Cannot produce nodular graphite structure |
Magnesium vaporization risk; requires ladle treatment |
Sourcing Recommendation from ZhenAn: For standard steel deoxidation and general foundry inoculation, ferrosilicon (FeSi72 or FeSi75) remains the most cost-effective choice. When ultra-clean steel or deep desulfurization is required, consider CaSi or Al-based deoxidizers with subsequent calcium treatment. For ductile iron production, FeSiMg is indispensable and should be sourced separately. ZhenAn supplies FeSi72 and FeSi75 in multiple size fractions to match your process requirements. Contact our technical team for grade selection guidance.
Quality Assurance
Certified Standards Compliance
All ferrosilicon products are manufactured and tested in accordance with internationally recognized standards:
GB/T 2272-2020 - Chinese national standard for ferrosilicon
ASTM A100 - Standard specification for ferroalloys
ISO 5445 - International standard for ferrosilicon classification and technical delivery conditions
Mill Test Certificate (MTC)
Every production batch is accompanied by a complete Mill Test Certificate documenting:
Chemical composition analysis (Si, C, Al, P, S, and other specified elements)
Particle size distribution
Batch number and production date
Testing methodology and equipment calibration status
Inspector certification and quality seal
Testing Methods
Chemical composition is determined via X-ray fluorescence (XRF) spectrometry and inductively coupled plasma (ICP) analysis in accordance with ISO/TC 132 testing protocols. Particle size is verified through standardized sieve analysis. Third-party inspection by SGS, Intertek, or equivalent agencies is available upon request.
Packaging & Logistics
Packaging Options
|
Packaging Type |
Specification |
Typical Application |
|---|---|---|
|
Bulk Bag (Jumbo Bag) |
1,000 – 1,250 kg per bag, UV-stabilized PP woven with inner liner |
Bulk ocean freight, steel mill delivery |
|
Small Bag |
25 kg per bag, moisture-proof multi-ply kraft or PP |
Sample shipments, small-batch orders |
|
Custom Packaging |
Per customer specification |
Special handling or end-user requirements |
All export packaging includes moisture barrier inner lining and palletization for safe handling during ocean transport.
Shipping & HS Classification
HS Code: 7202.21.00 (Ferrosilicon containing more than 55% silicon)
Primary Shipping Methods: 20' / 40' container (FCL), bulk vessel (for orders > 5,000 MT)
Loading Port: [Specify per supply chain arrangement]
Transit Time: Varies by destination; typical range 15–45 days
Minimum Order Quantity (MOQ)
Standard MOQ: 20 MT (one 20' FCL container load)
Trial Orders: 5–10 MT available for first-time buyers
Bulk Contracts: Annual or quarterly supply agreements for 500+ MT with fixed pricing structures
How to Choose a Reliable Ferrosilicon Supplier
Selecting the right ferrosilicon supplier is critical for consistent metallurgical performance and supply chain stability. Consider the following criteria:
Q: What certifications should a ferrosilicon supplier hold? A: A reliable supplier should provide products tested to recognized standards (GB/T 2272-2020, ASTM A100, or ISO 5445) and issue a Mill Test Certificate (MTC) for every batch. ISO 9001 quality management certification at the production facility is also a strong indicator of process control.
Q: How can I verify the chemical composition before placing a large order? A: Request a pre-shipment sample (typically 1–2 kg) with accompanying MTC for independent laboratory verification. Reputable suppliers support third-party inspection by agencies such as SGS or Intertek at the loading port.
Q: What particle size should I specify for my application? A: Steelmaking ladle additions typically use 10–50mm lumps; foundry inoculation requires 0.5–5mm granules or powder; Pidgeon process reductant is typically 10–80mm. Your supplier should advise on optimal sizing based on your furnace type and process parameters.
Q: How do I assess a supplier's production capacity and delivery reliability? A: Request documented monthly or annual production capacity, inquire about typical lead times from order to shipment, and ask for references from existing buyers in your region. Suppliers with direct production capability (not trading-only) generally offer better quality control and pricing stability.
Q: What terms should I negotiate beyond price? A: In addition to unit pricing, clarify: (1) payment terms (typically 30% T/T deposit, 70% against B/L copy or L/C at sight), (2) delivery Incoterms (FOB, CIF, or DAP), (3) quality claim procedures and penalty clauses for off-spec material, and (4) packaging specifications tailored to your unloading and handling equipment.
Frequently Asked Questions (FAQ)
Q1: What is ferrosilicon used for? A: Ferrosilicon is primarily used as a deoxidizer and alloying agent in steelmaking, as an inoculant in cast iron foundries, and as a reducing agent in magnesium metal production via the Pidgeon process. It is also used in welding fluxes and heavy medium mineral separation.
Q2: What is the difference between FeSi75 and FeSi65? A: The numerical designation indicates the minimum silicon content by weight. FeSi75 contains at least 75% silicon, while FeSi65 contains at least 65% silicon. Higher silicon grades (FeSi75, FeSi72) are preferred for applications requiring stronger deoxidation or higher silicon addition efficiency.
Q3: What is the typical chemical composition of ferrosilicon? A: Standard ferrosilicon contains 65–75% silicon, with carbon ≤ 0.20%, aluminum ≤ 2.0%, phosphorus ≤ 0.04%, and sulfur ≤ 0.02%. The remainder is iron. Custom low-aluminum and other specialty grades are available.
Q4: What is a Mill Test Certificate (MTC)? A: An MTC is a quality document issued by the manufacturer certifying that the delivered batch meets specified chemical and physical requirements. It includes test results, batch identification, testing standards, and inspector certification.
Q5: What particle sizes are available for ferrosilicon? A: Standard sizes include 0-1mm, 1-3mm, 3-10mm, 10-50mm, and 50-100mm. Custom sizing is available to match specific furnace charging systems and process requirements.
Q6: What is the HS code for ferrosilicon? A: The Harmonized System code for ferrosilicon containing more than 55% silicon is 7202.21.00.
Q7: How is ferrosilicon packaged for export? A: Ferrosilicon is typically packed in 1,000–1,250 kg jumbo bags with moisture-proof inner lining, or in 25 kg small bags. All export packaging is designed to prevent moisture absorption during ocean transit.
Q8: What is the shelf life of ferrosilicon? A: When stored in a dry, ventilated environment on raised platforms, ferrosilicon remains stable for 3–5 years. Powder grades require sealed packaging to prevent oxidation and moisture uptake.
Q9: Can ferrosilicon be customized for specific applications? A: Yes. Customization options include silicon content adjustment, low-aluminum formulations, specific particle size distributions, and special packaging. Technical consultation is recommended to match specifications to process requirements.
Q10: What quality standards does your ferrosilicon meet? A: Our ferrosilicon is manufactured and tested in compliance with GB/T 2272-2020 (Chinese national standard), ASTM A100 (U.S. standard), and ISO 5445 (international standard). Copies of conformance declarations are available upon request.
Call to Action
Request a Quote
Contact ZhenAn today for competitive pricing on FeSi75, FeSi72, FeSi70, FeSi65, and specialty ferrosilicon grades. Our technical team is available to assist with grade selection, particle size optimization, and custom specifications.
[Request a Quote] - Submit your inquiry with required grade, quantity, and delivery destination.
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[Download Product Datasheet (PDF)] - Complete technical specifications in printable format.
Contact ZhenAn
WhatsApp: +86 15518824805
Email: market@zanewmetal.com
HS Code: 7202.21.00 | Product: Ferrosilicon (FeSi) | Standards: GB/T 2272-2020, ASTM A100, ISO 5445
All technical data provided is representative of standard production. Custom specifications available upon request. Contact for pricing and availability.