Gallery, Projects and General > How do I??

Disposing of Hydrofluoric Acid

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awemawson:
About twelve years ago I bought a Zinc Plating Kit - "Zinc-Fast XL" from Tec-Nick. It has remained unopened until yesterday when I spotted it on a shelf.

Obviously contains several chemicals - Potassium Chloride, Boric Acid, Nitric Acid, Hydrochloric acid, and various organic 'brighteners' all of which I'm comfortable with handling and storing.

However one bottle - a 'Passivator' says the it contains  :bugeye: :bugeye: HYDROFLUORIC ACID  :bugeye: :bugeye:

Now it may only be very diluted, but this stuff is REALLY REALLY nasty stuff - causes dreadful burns, and is absorbed by the flesh and penetrates to attack bone.

I don't want to panic, as the quantities must (I hope) be very small, and it's ?? safely ?? in a polythene sealed bottle (always used to be 'gutta percha' when I was at school), but I don't want this stuff around - I want to safely dispose of it.

The original company seem to be long gone so no advice there, so are there any chemists on the forum who can make suggestions?

Pete.:
What's it taste like? :D

Neutralisation is shown here:

=245

drmico60:
The best way to make hydrofluoric acid safe is to dilute it and then neutralise it with calcium hydroxide (hydrated lime available from any builders merchant). This converts the acid into insoluble calcium fluoride which is safe in the environment. Calcium fluoride is a common mineral in nature (fluorspar).

Hydrofluoric acid is dangerous to handle. Use polyethylene containers and wear suitable protective clothing (full face mask, plastic apron, wellington boots, vinyl or nitrile gloves as a minimum).

Mike

John Stevenson:
Must be a lot of it about.

Post on the ME forum on the same subject.

http://www.model-engineer.co.uk/forums/postings.asp?th=110485

Be aware though these are Muddle enjuneers with mole skin trousers and welded to armchairs.

Eugene:
Andrew,

Even though it's a piddling quantity, I wouldn't recommend that you try and dispose of this yourself. The other components of a passivate concentrate will be just as environmentally nasty as the HF, notably chromates which will be present in the hexavalent form; streng verboten these days. I live on the headwaters of the Severn in the Welsh hills, and as a one time development and process chemist in the plating industry, would not dispose of the material other than through a recognised and licensed outlet.

First, best and cheapest option .... phone the nearest plating shop and ask for the chief chemist. Very likely for a tenner into the Christmas beer fund, he'll drop it in the effluent treatment plant for you. There may even be some mechanical type favour you could do for him; just explain what you do.

Contact a specialist disposal company. I was instrumental in setting up the hazardous waste disposal side of Veolia a good few years back. I'm out of touch with them now, but they are a reputable outfit who even if they can't help directly could give you advice. There also outfits in Sussex / Kent who may be able to help if you Google them up; the MSDS and / or data sheet would be a big help to them.

Eug

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