Ferro Silicon 15% for DMS
Atomised 15% ferrosilicon — the working medium in dense medium separation, supplied in Coarse, Fine and Cyclone 60.
Dense medium separation works by suspending finely divided ferrosilicon in water to make a fluid of a chosen density. Feed heavier than that fluid sinks, feed lighter than it floats, and the separation is only as sharp as the medium is stable. Ferrosilicon at 14–16% silicon is the industry standard above roughly 3.0 relative density because it holds five properties at once: high specific gravity, strong magnetic response for recovery and demagnetisation, resistance to abrasion, resistance to corrosion, and low cost per unit of density.
Ours is water‑atomised — molten alloy broken into rounded, near‑spherical particles, then dried and classified to grade. Rounded particles make a more fluid suspension at the same density, carry less surface area to corrode, and adhere less to the product streams on the way out.
That last point decides the economics. The medium is not consumed: it is recovered magnetically and returned to the circuit, so what a plant buys each year is the make‑up for whatever escaped. A powder that resists corrosion and reports cleanly to the magnetic separators costs less over a year than one bought on price per tonne.
Two things worth knowing before you specify. The smaller the cyclone, the higher the centrifugal force and the finer the medium needed to stay stable — but specifying a finer grade than the duty requires is the most common avoidable cost in a DMS circuit, because media loss concentrates in the sub‑45 µm fraction that drains and slips past the magnetic separators most readily.
And atomised ferrosilicon needs roughly four times the demagnetising coil field strength that milled does. A circuit converting from milled to atomised should check its demag capacity first — high viscosity after a changeover is far more often a recovery problem than a powder problem.
Forms & grades supplied
- Coarse — drums, static baths, large cyclones
- Fine — the general-purpose grade
- Cyclone 60 — the mainstream dense medium cyclone grade
- 1 MT jumbo bags with moisture-barrier liner, or 25 kg palletised
Industries served
Ask us for
- Chemical specification and test certificate
- Particle size / mesh range
- Packing options and lead time
- A sample for trial
Technical data sheet
Atomised ferrosilicon of 14–16% Si is the industry-standard medium for sink–float separation above roughly 3.0 relative density. All three grades share one chemistry and one particle shape — they differ only in size distribution, and that difference is what governs medium stability, viscosity, achievable density and media loss in your circuit.
| Element | Specification | Remarks |
|---|---|---|
| Silicon (Si) | 14.0 – 16.0% | The optimum window. Below 14% corrosion resistance falls away sharply; above 16% both specific gravity and magnetic response deteriorate. |
| Iron (Fe) | 80% min | Balance |
| Carbon (C) | 0.5% max | — |
| Sulphur (S) | 0.05% max | — |
| Phosphorus (P) | 0.10% max | — |
| Aluminium (Al) | 0.50% max | — |
| Manganese (Mn) | 0.75% max | — |
| Chromium (Cr) | 0.50% max | — |
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| Property | Value | Method |
|---|---|---|
| Relative (true) density | 6.7 – 7.1 g/cm³ | Pycnometer, paraffin wetting |
| Apparent (bulk) density | 3.0 – 4.2 g/cm³ | Loose poured |
| Magnetic content | 99% min | Magnetic balance / Satmagan-type |
| Sphere content | 90% min (cyclone grades) | Optical microscopy |
| Non-magnetics | 1.0% max | Davis tube / magnetic separation |
| Moisture | 0.2% max | Loss on drying at 105 °C |
| Particle shape | Spherical to rounded | Water atomised |
| Colour | Silver to dark grey | — |
| Melting range | 1210 – 1380 °C | — |
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| Aperture | Coarse | Fine | Cyclone 60 |
|---|---|---|---|
| 355 µm | 99 | 99 | 100 |
| 150 µm | 90 | 95 | 99 |
| 45 µm | 38 | 45 | 70 |
| 38 µm | — | — | 65 |
| −45 µm, limits | 32 – 42 | 40 – 50 | 65 – 75 |
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Sizing by wet screening to 45 µm and 38 µm, with sub-sieve methods below 38 µm. The −45 µm band is the controlling specification. The values above are the industry-standard windows for atomised FeSi 15%; every consignment is certified against its own batch analysis.
| Grade | Medium RD | Separator | Typical duty |
|---|---|---|---|
| Coarse | 2.8 – 3.2 | Drums, static baths, cyclones > 600 mm | Coarse feed. Lowest viscosity, lowest media loss, easiest drainage and magnetic recovery. |
| Fine | 3.0 – 3.4 | Baths and cyclones 500 – 800 mm | The general-purpose grade — a balance of stability and loss. |
| Cyclone 60 | 3.2 – 3.6 | Dense medium cyclones 350 – 600 mm | The mainstream DMC grade: diamonds, iron ore, chrome, base metals. |
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RD ranges are indicative operating windows. Final grade selection should be confirmed by plant test work — send us your circuit and we will go through it with you.
| Industry | Typical cut RD | Grade | Role of DMS |
|---|---|---|---|
| Diamonds / kimberlite | 2.6 – 3.2 | Cyclone 60 | Primary and recovery cyclones. The sharpest possible cut protects revenue. |
| Iron ore (hematite, DSO) | 3.0 – 3.8 | Cyclone 60 | Silica and alumina rejection — the classic high-density atomised duty. |
| Chromite / chrome | 2.8 – 3.2 | Fine / Cyclone 60 | Pre-concentration of UG2 and lumpy chrome ahead of spirals. |
| Manganese | 2.9 – 3.4 | Fine / Cyclone 60 | Upgrading of lumpy and pebble fractions. |
| Lithium (spodumene, petalite) | 2.6 – 2.9 | Coarse / Fine | Coarse gangue rejection ahead of flotation — a rapidly growing application. |
| Base metals — Cu, Pb, Zn, Ni, Sn, Sb | 2.7 – 3.2 | Fine / Cyclone 60 | Waste rejection at crush size; mill feed grade uplift. |
| Fluorspar, barite, garnet, gemstones | 2.7 – 3.2 | Fine / Cyclone 60 | Industrial mineral upgrading. |
| Bauxite | 2.4 – 2.8 | Coarse / Fine | Silica rejection. |
| Aggregate, limestone, C&D waste | 2.2 – 2.6 | Coarse | Removal of porous, weathered and contaminant fractions. |
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Ferrosilicon carries a true density of about 6.8–7.1 g/cm³ against magnetite’s 4.5, so it reaches medium densities magnetite cannot. Below about 2.9 RD, milled ferrosilicon or magnetite is usually the lower-cost medium; atomised is specified below that density where sharpness of cut, corrosive circuit water, porous ore or high adhesion losses justify it.
| Stage | Medium RD | What separates |
|---|---|---|
| Stage 1 | approx. 2.2 | Magnesium, plastics, rubber and light residue float; all metals sink. |
| Stage 2 | approx. 3.2 | Aluminium floats as clean Twitch; copper, brass, zinc, lead and stainless sink as a heavy-metal concentrate. |
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The 3.2 RD second stage is the decisive one. At that density milled ferrosilicon becomes too viscous for an efficient separation, so atomised FeSi 15% — Fine or Cyclone 60 — is the practical medium. Upgrading Zorba to furnace-ready Twitch captures the spread between mixed-scrap and clean-metal pricing, and the medium’s magnetic recoverability keeps consumption low.
Please note. These are indicative industry-standard ranges shown for guidance. Where a grade name encodes a nominal sieve or density, that is what the designation means in the trade — the size range actually supplied, and the packing, are set to your requirement and confirmed on your order. The binding specification for any order is the one on your purchase order and the test certificate supplied with the consignment — see how we test and certify a lot. Ask us for a datasheet for the exact grade you need.
Ferro Silicon 15% for DMS in use
Where Ferro Silicon 15% for DMS is used
- Diamonds and kimberlite
- Iron ore — silica and alumina rejection
- Chromite, manganese and base metal pre-concentration
- Lithium — coarse gangue rejection ahead of flotation
- Aluminium and metal scrap recycling — Zorba to Twitch
- Fluorspar, barite, garnet and gemstones
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