Iron filings (CAS 7439-89-6): storage and disposal

Iron filings are a staple of school and college prep rooms, usually in a plastic tub or a small tin, with iron powder held in some university stores. Ordinary iron filings are not classified as hazardous on the sources checked, so damp, rust and waste paperwork are the main concerns. Fine iron powder can have additional fire hazards depending on its particle size and form.

CAS number: 7439-89-6
Form: Solid
Storage class: General
Usual EWC code: 16 05 09

What to do this week

Check the label is readable and write down the opened date if it is not already there.
Check it is stored as general stock and apart from the items listed under "Do not store with".
If you no longer need it, add it to your disposal list so it goes on the next collection.

Safe storage in a school or lab

Filings usually arrive in a screw-top tub or small tin, and the lid matters because damp is the one thing they dislike. A dry, labelled, well organised general store is the right place, with the date written on arrival. Iron is not classified as hazardous on the sources we checked, but it still reacts badly with some neighbours. Keep it apart from calcium hypochlorite, chromium trioxide, hydrogen peroxide, potassium chlorate and potassium dichromate, which can form mixtures that burn fiercely or explode. Keep it away from picric acid and its products too, which form shock sensitive picrates with metals. Teaching stock often sits on open shelves, so check that nothing from that list is nearby.

How to tell it has deteriorated

Bright grey filings turn orange brown with rust, and that is the change to look for. A light rusty tint is cosmetic, but filings that have clumped into a cake or stuck to the base of the tub have been damp. Rust can stain the inside of a tub, a metal lid and the label, and a small steel tin may rust at the seams. This substance gives few other visible signs, so look at the container instead: a faded label, split plastic, a lid that will not turn and an unknown date of receipt. Filings that have fused into a solid lump should be recorded as such, not broken up.

How it must be disposed of

By specialist collection only. It never goes down the drain or into general waste. It is normally packed in a non-regulated or low hazard laboratory pack with compatible chemicals.

Before asking for a collection, note what the container is, how full it is, whether the filings are loose or caked with rust and whether the label still reads clearly. Iron filings are not classified as hazardous on the sources we checked, so the usual entry is 16 05 09, a code without an asterisk, and the paperwork is a waste transfer note. They are still a chemical waste and need an accurate description. The only route is specialist collection: they must not go into a sink, a drain, a general waste bin or a skip, and nobody should try to treat them first. Small tubs are packed in compatible groups in a lab pack, away from the chemicals named in the storage note.

Waste codes and transport details for Iron filings
EWC code, laboratory chemicals	16 05 09
Hazardous waste	No

The code depends on where the waste came from and what it is mixed with. Use the waste code finder to see why.

Do not store with

Named chemicals to keep apart

Ammonium picratePicric acid forms shock sensitive metal picrates with metals.
Calcium hypochloriteStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
Chromium trioxideStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
Hydrogen peroxideStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
Picric acidPicric acid forms shock sensitive metal picrates with metals.
Potassium chlorateStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
Potassium dichromateStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
Potassium permanganateStrong oxidisers can form mixtures with these materials that burn fiercely or explode.

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Sodium azideAzides form shock sensitive metal azides with lead, copper, brass and similar metals.
Sodium chlorateStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
Sodium dichromateStrong oxidisers can form mixtures with these materials that burn fiercely or explode.

Common quantities we collect

Usually held as: filings, powder.

Part-used bottles and full containers are both fine. Tell us the size and how many, and an estimate is enough for a first price.

Where it is commonly held

Questions

Do rusty iron filings need to be disposed of differently?

Rust does not change how they are described. Record them as iron filings and mention that they are caked or rusted. They are not classified as hazardous on the sources we checked, but they remain chemical waste, so they do not go into general waste or down a drain.

Can iron filings go in the bin with ordinary school waste?

No. Iron filings stay a chemical waste even though they are not classified as hazardous on the sources we checked, and the collector needs an accurate description. Keep them in their labelled container for specialist collection and do not try to treat them first.

Where should iron filings be stored in a prep room?

A dry, labelled general-store shelf is suitable for ordinary iron filings. Fine iron powder may require different storage according to its specific physical hazards. Keep the container tightly closed to limit rust, and keep it away from picric acid products and the chemicals named in the storage note, which can form shock sensitive picrates with metals.