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If you're a steel mill purchaser ordering deoxidizer for next quarter, a foundry metallurgist specifying inoculant for a new ductile iron grade, or a buyer comparing quotes from Chinese ferroalloy producers — the FeSi 75 vs FeSi 72 question is probably on your mind. The two grades differ by roughly 3 percentage points of silicon content, but the practical impact on steel chemistry, addition rate and cost-per-tonne-of-silicon delivered can be significant.
This guide walks through what ferrosilicon actually is, the standard commercial grades, when each grade is the right choice, and current 2026 pricing — written for the procurement and metallurgy audience who need clear answers without marketing fluff.
1. What is Ferrosilicon (FeSi)?
Ferrosilicon (FeSi) is a binary iron-silicon alloy used primarily as a deoxidizer and alloying agent in steelmaking, and as an inoculant in iron foundry casting. It is produced by reducing silica (SiO₂) with carbon (coke) in the presence of iron, in a submerged-arc furnace at ~1700°C:
SiO₂ + 2 C + Fe → FeSi + 2 CO
The reaction is electricity-intensive — Chinese producers consume roughly 8,000–9,000 kWh of electricity per tonne of FeSi 75. That's why FeSi production concentrates in Chinese provinces with abundant cheap power: Ningxia, Qinghai and Inner Mongolia together produce over 70% of global ferrosilicon supply.
The finished alloy contains 65–80% silicon depending on the grade, with iron making up most of the balance plus small amounts of carbon (0.1–0.2%), aluminium (1.0–2.0%), phosphorus (≤ 0.04%) and sulphur (≤ 0.02%).
2. The 4 Commercial FeSi Grades
Chinese national standard GB/T 2272-2009 defines four commercial ferrosilicon grades. The grade number indicates the silicon content:
| Grade | Si % | C max | Al max | P max | S max | Primary use |
|---|---|---|---|---|---|---|
| FeSi 65 | 65–68 | 0.20% | 2.0% | 0.05% | 0.02% | Cost-sensitive deoxidation |
| FeSi 72 | 72–75 | 0.15% | 2.0% | 0.04% | 0.02% | Workhorse grade |
| FeSi 75 | 75–80 | 0.10% | 1.5% | 0.04% | 0.02% | Premium deoxidation |
| FeSi 90 | ≥ 90 | 0.08% | 1.0% | 0.04% | 0.02% | Specialty / electrical steel |
FeSi 72 and FeSi 75 together account for roughly 85% of global ferrosilicon consumption. The other two grades (65 and 90) serve specific market segments — FeSi 65 for budget applications and FeSi 90 for premium electrical-grade steel production.
3. FeSi 75 vs FeSi 72 Head-to-Head
Here's the practical comparison for procurement decisions:
| Parameter | FeSi 72 | FeSi 75 |
|---|---|---|
| Silicon content (typical) | 72–73% | 75–76% |
| Dissolution rate in molten steel | Moderate | Faster (higher Si %) |
| Si delivered per kg of alloy | ~725 g | ~755 g |
| FOB China price (2026) | $1,150–1,350/MT | $1,250–1,500/MT |
| $ per tonne of Si delivered | ~$1,650 | ~$1,750 |
| Carbon contamination (C max) | 0.15% | 0.10% |
| Aluminium contamination (Al max) | 2.0% | 1.5% |
| Best for | General steelmaking, casting | Premium steel, electrical grades |
Procurement rule of thumb: FeSi 75 costs ~$100–150/MT more than FeSi 72 but only delivers ~4% more silicon per kg. The premium is justified mainly when (a) you need tighter aluminium/carbon control, (b) ladle space or charge weight constraints favor higher-Si grades, or (c) you produce electrical or spring steel where impurity limits matter. For general carbon steel and routine deoxidation, FeSi 72 is the better cost-per-Si choice.
4. The 3 Main Applications
Application 1: Steel Deoxidation (largest market)
Silicon is a stronger reducing agent than carbon for dissolved oxygen in molten steel. When ferrosilicon is added to a steel ladle, the Si reacts with O₂ to form SiO₂ (silica), which floats up into the slag. Typical addition rate: 2–5 kg FeSi per tonne of liquid steel, depending on initial oxygen content and desired silicon level in the finished steel.
EAF mills typically prefer FeSi 72 for routine deoxidation. Higher-Si grades (FeSi 75 or 90) are used when:
- Producing low-aluminium killed steel (Al < 0.02%)
- Producing electrical / silicon steel (final Si target 2.5–4.5%)
- Ladle space is tight and lower addition mass is preferred
Application 2: Steel Alloying
Several steel grades require silicon as an alloying element rather than just a deoxidizer:
- Silicon steel / electrical steel: 2.5–4.5% Si for transformer cores and motor laminations
- Spring steel (e.g. 60Si2Mn): 1.6–2.0% Si
- Heat-resistant steel: 1.0–2.5% Si for improved oxidation resistance
- Stainless steel: 0.5–1.5% Si for fluidity and oxidation resistance
For these grades, FeSi 75 is preferred because the tighter Al limit (≤ 1.5% vs FeSi 72's ≤ 2.0%) reduces unwanted aluminium pickup that can affect electrical resistivity or hardenability.
Application 3: Foundry Inoculation
In cast iron production (grey iron and ductile iron), FeSi inoculant is added to the molten metal during the late stages of melting or in the ladle to promote graphite nucleation. This affects the microstructure — encouraging fine, evenly distributed graphite flakes (grey iron) or spheroidal graphite nodules (ductile iron).
Inoculant-grade FeSi 75 is typically ground to 0.2–0.7mm or 0.7–2mm powder and may be modified with calcium, barium, strontium or zirconium to enhance specific nucleation effects. Typical addition rate: 0.3–0.6% of melt weight.
5. Sizing: Lump, Granular and Powder
Standard ferrosilicon sizes match the application:
| Form | Sieve range | Application |
|---|---|---|
| Lump | 10–50mm, 10–100mm, 50–100mm | EAF charging, BOF |
| Granular | 3–10mm, 10–25mm | Ladle deoxidation, ladle injection |
| Powder (coarse) | 0.7–2mm, 2–7mm | Foundry inoculation, welding |
| Powder (fine) | 0.2–0.7mm, 0–0.2mm | Late-trim inoculation, cored wire |
Mesh-sized powder (60-mesh, 100-mesh) is also produced for specific applications like cored wire feeding and welding consumables.
6. 2026 FOB China Pricing
Indicative FOB China ferrosilicon pricing as of mid-2026:
| Grade | FOB China (USD/MT) | Form |
|---|---|---|
| FeSi 65 lump | $1,050–1,250 | 10–50mm |
| FeSi 72 lump | $1,150–1,350 | 10–50mm or 10–100mm |
| FeSi 75 lump | $1,250–1,500 | 10–50mm |
| FeSi 75 powder | $1,350–1,650 | 0.2–2mm |
| FeSi 90 | $1,800–2,400 | Various |
Prices are highly sensitive to Chinese electricity costs (FeSi production is among the most power-intensive industrial processes). Watch for:
- Seasonal power tariffs in Ningxia/Qinghai/Inner Mongolia — winter heating demand spikes can push prices up 5–10%
- Magnesium production demand — FeSi 75 is a major reductant for Pidgeon-process magnesium, which competes with steel deoxidation demand
- Anti-dumping duties — EU and Japan periodically impose anti-dumping margins on Chinese FeSi imports; check your destination country regulations
7. Sourcing FeSi from China
China produces over 70% of global ferrosilicon, with the major production clusters in Ningxia (Shizuishan, Wuzhong), Qinghai (Xining, Haixi), and Inner Mongolia (Wuhai, Erdos). For procurement teams sourcing FeSi from China in 2026, the key items to verify:
- Mill Test Certificate (COA) with lot-traceable Si, C, Al, P, S analysis
- SGS / Bureau Veritas / Intertek pre-shipment inspection for orders ≥ 100 MT
- Sieve analysis: % passing each specified screen — ensures correct lump/granular ratio
- Anti-dumping documentation for relevant destinations (EU CN code, anti-dumping certificate of origin)
- Sample qualification: 1–2 kg sample to your lab before bulk order
Global Vista Group supplies ferrosilicon (FeSi 65/72/75/90) from Hong Kong, sourced from qualified Chinese producers in Ningxia, Qinghai and Inner Mongolia. Lot-traceable COA, third-party pre-shipment inspection, USD/EUR/JPY settlement. Browse our broader product range or request a quote with your grade, size and destination port.
8. Frequently Asked Questions
What is the difference between FeSi 75 and FeSi 72?
The number is silicon content. FeSi 75 contains 75–80% Si, FeSi 72 contains 72–75% Si. FeSi 75 has slightly faster dissolution and tighter impurity limits (lower C, Al). FeSi 72 is the workhorse grade for routine steelmaking; FeSi 75 is preferred for premium steel grades and applications requiring lower aluminium.
What is FeSi 75 used for?
EAF steel deoxidation, silicon-alloying for electrical and spring steel, magnesium production reductant (Pidgeon process), and as ground powder for ductile iron foundry inoculation.
What are the standard FeSi grades?
Per Chinese GB/T 2272-2009 standard: FeSi 65, FeSi 72, FeSi 75 and FeSi 90. FeSi 72 and 75 dominate the market at ~85% of global consumption. See section 2.
What size FeSi do I need?
EAF charging: lump 10–50mm. Ladle deoxidation: granular 3–10mm. Foundry inoculation: powder 0.2–0.7mm or 0.7–2mm. See section 5 for the full breakdown.
How much does ferrosilicon cost?
2026 FOB China indicative: FeSi 65 $1,050–1,250/MT, FeSi 72 $1,150–1,350/MT, FeSi 75 $1,250–1,500/MT, FeSi 90 $1,800–2,400/MT. Powder grades sell at $100–200/MT premium over lump. See section 6.
Why is ferrosilicon so power-intensive to produce?
The reduction reaction (SiO₂ + 2C → Si + 2CO) requires temperatures around 1700°C in a submerged-arc furnace. Chinese producers consume 8,000–9,000 kWh of electricity per tonne of FeSi 75 — making power cost the dominant production input. This is why FeSi production concentrates in regions with cheap coal-fired or hydroelectric power.
This article is intended as general industry guidance. Specific grade selection should be validated against your finished steel/iron specification, local anti-dumping regulations and supplier-specific data. Global Vista shipments are delivered with lot-traceable COA and pre-shipment inspection.