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

Sulfur (CAS 7704-34-9): storage and disposal

Sulfur in school, college and university stores comes as fine powder, flowers of sulfur or roll sulfur. It is classified for skin irritation only, yet it burns to give toxic sulfur dioxide and fine dust can ignite. Its mixtures with oxidising chemicals are the real concern, and they decide where it is shelved and how a collection is planned.

CAS number
7704-34-9
Form
Solid
Storage class
General
Signal word
Warning
Usual EWC code
16 05 06*
  • Harmful or irritant pictogramHarmful or irritant

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 general 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

The usual mistake in a school prep room is shelving sulfur beside the chlorates and permanganate because both are old stock. Sulfur forms sensitive mixtures with oxidisers, and ammonium nitrate forms mixtures with it that can detonate. Keep it away from calcium hypochlorite, chromium trioxide, hydrogen peroxide, potassium chlorate, potassium dichromate, potassium permanganate and sodium chlorate. A dry, labelled, well organised store is right, dated on arrival, with powder in a tightly closed tub so dust does not spread across the shelf. Fine dust can ignite, so heat sources and naked flames have no place nearby.

How to tell it has deteriorated

Age does little to this element and it gives few chemical signs of its own. Flowers of sulfur is a fine pale yellow powder that gets everywhere. Roll sulfur is a brittle yellow stick that may crack or shed dust from the surface, and a grey or dirty coating suggests contamination from the shelf. Look at the container instead: a faded label, a split tub, powder escaping around the lid, yellow dust on neighbouring bottles and any loss of the stock record. Dust on the shelf matters because fine dust can ignite. Sulfur found mixed with another powder should be recorded as a mixture and not as sulfur.

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.

Unwanted stock leaves the site only through a specialist collector, which packs it in a compatible group in UN approved packaging well away from oxidisers. The entry is 16 05 06*, with UN 1350, and it is handled as hazardous waste even though the classification is for skin irritation. It must not be burned off, an obvious temptation with roll sulfur, because burning forms toxic sulfur dioxide, and it must not go down a sink or drain or into the bin or a skip. Record the form held, how much remains and whether the tub is sealed and free of spilled dust.

Waste codes and transport details for Sulfur
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

Named chemicals to keep apart

  • Ammonium nitrateAmmonium nitrate forms mixtures with these materials that can detonate.
  • 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.
  • 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.
  • Sodium chlorateStrong oxidisers can form mixtures with these materials that burn fiercely or explode.
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  • Sodium dichromateStrong oxidisers can form mixtures with these materials that burn fiercely or explode.

Common quantities we collect

Usually held as: powder, roll, flowers of sulfur.

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

  • H315 Causes skin irritation.
Precautionary statements
  • P264 Wash hands and exposed skin thoroughly after handling.
  • P280 Wear protective gloves, protective clothing, eye protection and face protection.
  • P302+P352 IF ON SKIN: Wash with plenty of water.
  • P321 Specific treatment (see supplemental first aid instruction on this label).
  • P332+P317 If skin irritation occurs: Get medical help.
  • P362+P364 Take off contaminated clothing. And wash it before reuse.

Substance as classified, dilutions may differ.

Questions

Is roll sulfur safer to store than powder?

Roll sulfur presents a lower dust ignition risk than fine powder while it remains intact, but it can still burn to produce toxic sulfur dioxide and can shed combustible dust as it crumbles. Both forms need separation from oxidisers and a dry, labelled shelf. Record the form for collection.

Can old sulfur be burned to get rid of it?

No. It burns to form toxic sulfur dioxide, and fine dust can ignite. Sulfur goes by specialist collection only. Keep it in its labelled container, away from oxidisers, and describe the form and amount when you ask for a collection.

How long can sulfur be kept on the shelf?

No fixed life is set for it. Sulfur gives few signs of age, so judge by the container: a legible label, a closed lid, a known date of receipt and no spilled dust. If the history is unknown or the sulfur is mixed with something else, record it as unknown and ask for advice.

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 S. EC number 231-722-6.

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