Ferrosilicon size specifications and selection guide

Q1: Why does ferrosilicon size specification matter?
A: Size affects how ferrosilicon is added, how fast it dissolves, and how much loss you get from fines. Oversized lumps may dissolve slowly or unevenly, while excessive fines can cause dust, oxidation loss, and inconsistent silicon recovery. Stable sizing supports repeatable furnace performance.

Q2: What are the common ferrosilicon size forms in trade?
A: The most common supply forms are:

• Lumps (used for many steelmaking additions)
• Granules (more controlled addition, often used in foundry or special dosing systems)
• Fines/Powder (used in some processes, but higher loss and dust control is needed)

Q3: What are typical ferrosilicon size ranges buyers ask for?
A: Actual availability depends on supplier crushing/screening lines, but common export requests include:

• Lumps: 10–50 mm, 10–60 mm, 50–100 mm, 10–100 mm
• Granules: 0–3 mm, 1–3 mm, 3–10 mm, 10–30 mm

Buyers should specify one primary range and an acceptable tolerance to avoid disputes.

Q4: How do steelmakers usually choose lump size?
A: Steel plants typically choose based on addition method and furnace type:

• For bulk addition and easy handling, buyers often select medium lumps (for stable feeding).

• If dissolution speed is critical, a smaller lump range may be preferred (but confirm fines control).

  The goal is consistent feeding without excessive dust or slow melting.

Q5: How do foundries choose granule vs lump?
A: Foundries often prefer granules when they need more controlled dosing and faster response, especially for inoculation practices. Granules can help improve distribution in the melt, but buyers should watch the fines ratio and request moisture protection to reduce oxidation.

Q6: What is "fines ratio" and what is a reasonable requirement?
A: Fines ratio means the percentage of material below the minimum size (for example, under 10 mm in a 10–50 mm spec). Buyers often set a maximum limit (e.g., "fines below X mm ≤ Y%"). The right limit depends on handling and the supplier's screening capability. The key is to define:

• The cut size (what counts as "fines")
• The maximum % allowed
• The sampling method used to measure it

Q7: What should I write in a contract for ferrosilicon size?
A: A strong purchase spec usually includes:

• Grade (e.g., FeSi 75 or FeSi 72) and impurity limits (Al, C, P, S if needed)
• Size range (e.g., 10–50 mm) with tolerance
• Maximum fines (e.g., "<10 mm ≤ X%") and how it's tested
• Packaging (1MT big bags / pallets / moisture-proof lining)
• Inspection: COA per lot, sampling standard, and dispute handling
• Marking/labels and net weight tolerance per bag

Q8: How does packaging relate to size performance?
A: Ferrosilicon can generate more fines if bags are handled roughly or exposed to moisture. Moisture-protected packaging and proper palletizing help reduce breakage, oxidation, and dust during shipping and storage, improving real yield on arrival.