Chromium metal (CAS 7440-47-3): storage and disposal

College and university stores tend to hold small jars of several metals, while school stores may keep a single old bottle. Either way chromium suits a dry, labelled, well organised general store, dated on arrival. Powder should be in a tightly closed tub, and flakes in a jar with a lid that sits square, because loose fine powder spreads across a shelf quickly. Keep it clear of damp and of the shelf below any leaking bottle. Jars of different metals look similar on a shelf, so each needs a legible label naming the metal and form. Separate it from food grade supplies.

Chromium looks much as it did when it arrived: a silvery grey flake or a dull grey powder. The substance gives few visible signs of age, so what a technician sees first is the container. Look for a faded label, a cracked or chipped jar, a lid that no longer closes, grey dust round the neck and a missing date of receipt. Powder that has clumped or flakes that sit in a damp lump suggest water has got in and should be recorded as such. Any colour change that does not fit grey metal is worth reporting as possible contamination.

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.

The code for the metal is 16 05 09, without an asterisk because it is not classified as hazardous on the sources we checked, and a waste transfer note covers the movement. It is still a chemical waste, so the powder and flakes are described by form and approximate amount, and a jar that has been topped up from another bottle is described honestly. Only a specialist collector should take it. It must not go into a sink, a drain, a general bin or a skip, and nobody should try to dissolve or process it first.

Usually held as: powder, flakes.

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.