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Chemical collection and stock control for UK schools, universities and hospitals

Aluminium powder (CAS 7429-90-5): storage and disposal

Aluminium powder sits in school, college and university stores beside foil offcuts, and the two are not equally demanding. The fine powder is a flammable solid that gives off flammable gas on contact with water. That water reactivity, more than the metal itself, decides where stock is kept and how a collection is prepared.

CAS number
7429-90-5
Form
Solid
Storage class
Flammable
Signal word
Danger
Usual EWC code
16 05 06*
  • Flammable pictogramFlammable

What to do this week

  1. Check the label is readable and write down the opened date if it is not already there.
  2. Check it is stored as flammable stock and apart from the items listed under "Do not store with".
  3. 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

Look at the tin where it sits, starting with the lid: a domed lid or a cap that hisses points to damp inside. Powder should sit in a ventilated fire-resistant cabinet with spill containment, dry, away from ignition sources and oxidisers. Fine powder releases hydrogen with water, acids and alkalis, so it should not share a shelf with acid bottles or alkali pellets. Keep it clear of ammonium nitrate, bromine and iodine, and of oxidising chemicals such as calcium hypochlorite, chromium trioxide and hydrogen peroxide. Picric acid products, including ammonium picrate and Bouin's fluid, form shock sensitive picrates with metals. Foil offcuts are less demanding, but label them clearly so they are not confused with the powder.

How to tell it has deteriorated

Plain metal ages slowly, so the first change to expect is a dull grey surface where the powder was once brighter. That is an oxide skin forming and is normal. Moisture matters far more. Powder that has clumped, turned to a grey paste or set into a cake has been wet, and damp powder in a sealed tin can build pressure, so a bulging or domed lid is a warning. Look also for corrosion on the tin, a split seal, a label stained by leakage and any tin that has lost its stock record. Foil simply dulls and may crease or flake. If a lid is distorted, leave it closed and do not shake or carry the tin about.

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 flammable laboratory pack with compatible chemicals.

Waste code 16 05 06* is the usual entry for a tin of powder, and the asterisk means it is treated as hazardous waste from the moment it is listed. UN 1396 belongs in the description. The only route is specialist collection: the powder must not go into a sink, a drain, a general waste bin or a skip, and nobody should try to treat it first. Record the form held, whether the tin is sealed and dry, and the state of the lid, since a swollen lid changes how a collector handles it. Foil offcuts can be listed separately. Everything is packed in a compatible group in UN approved packaging, away from oxidisers, acids and water.

Waste codes and transport details for Aluminium powder
EWC code, laboratory chemicals16 05 06*
Discarded inorganic chemical, not a laboratory pack16 05 07*
Hazardous wasteYes

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

  • OxidiserOxidisers can ignite flammable materials or make a fire far more intense.
  • AcidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • CorrosiveA leak of corrosive stock can break down flammable containers and feed a fire.

Named chemicals to keep apart

  • Acetic acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Ammonium nitrateAmmonium nitrate forms mixtures with these materials that can detonate.
  • Ammonium picratePicric acid forms shock sensitive metal picrates with metals.
  • BromineBromine reacts violently with ammonia, reactive metals and many solvents.
  • 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.
  • Hydrochloric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Hydrogen peroxideStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
Show 15 more
  • IodineIodine forms sensitive or violently reacting products with ammonia and reactive metals.
  • MercuryMercury forms amalgams or unstable compounds with these materials.
  • Nitric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • 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 hydroxideStrong alkalis release flammable hydrogen with these metals.
  • Potassium nitrateOxidisers can ignite flammable materials or make a fire far more intense.
  • Potassium permanganateStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
  • 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.
  • Sodium hydroxideStrong alkalis release flammable hydrogen with these metals.
  • Sulfuric acidOxidising acids can ignite flammable materials, and acid fumes attack containers and seals.
  • Thionyl chlorideA leak of corrosive stock can break down flammable containers and feed a fire.

Common quantities we collect

Usually held as: powder, foil.

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

Hazard statements

  • H228 Flammable solid.
  • H261 In contact with water releases flammable gases.
Precautionary statements
  • P210 Keep away from heat, hot surfaces, sparks, open flames and other ignition sources. No smoking.
  • P231+P232 Handle and store contents under inert gas. Protect from moisture.
  • P240 Ground and bond container and receiving equipment.
  • P241 Use explosion-proof electrical, ventilating and lighting equipment.
  • P280 Wear protective gloves, protective clothing, eye protection and face protection.
  • P370+P378 In case of fire: Use suitable extinguishing media to extinguish.
  • P402+P404 Store in a dry place. Store in a closed container.
  • P501 Dispose of contents and container in accordance with local, regional, national and international regulations.

Substance as classified, dilutions may differ.

Questions

Is aluminium foil in the prep room handled the same way as the powder?

Describe each form separately when you ask for a collection. The powder is the main concern because it is a flammable solid that releases flammable gas with water. Foil is less demanding to hold, but both stay chemical waste and neither goes into general waste.

Can damp aluminium powder be left to dry out on the bench?

No, and nobody should try to dry or treat it. Damp powder in a sealed tin can build pressure, and the gas it gives off is flammable. Keep it away from ignition sources, leave a bulging tin where it is, and raise a collection enquiry so it can be assessed.

How long can an opened tin stay on the shelf?

No fixed shelf life is given for this substance. What counts is whether the powder has stayed dry and the tin is sound. Date tins on arrival, check lid and seal at each stock check, and treat a clumped, damp or bulging tin as a disposal candidate rather than topping it up.

Guidance only. Check your own risk assessment and your supplier's safety data sheet.

Hazard data source: PubChem GHS Classification, retrieved 31 Oct 2026. Formula Al. EC number 231-072-3.

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