Disposing of Hydrofluoric Acid

[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  HYDROFLUORIC ACID 

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?

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

[awemawson]

Thanks for all the responses and to JohnS for that interesting link.

Eug: the instructons specifically say the process involves no chromates 

A BIG development is that I've tracked down the original company who ARE still in business  I had a fraction of their address including Haltwhistle on the original packing. Now we all know that Haltwhistle is a delightful small town in Northumberland with some good pubs and at least one good restaurant, so it was in that area I was searching. Turns out that they are in ' Haltwhistle Road, South Woodham Ferrars in Essex 

.... I'll give them a call in the morning 

[vtsteam]

Andrew, maybe you could sell it back to them.......

Hmmm, this sounds like a dynamite business plan! Sort of a double-pay fear based rental return 

[awemawson]

Well it's now gone 

Tracking the original firm down proved to be a red herring - company not trading and address proved to be a private house - odd as there is a strong 'web presence'  but it looks as though it was never a 'Ltd' company and the house has changed hands !

So I took advice from both here and elsewhere and, donning major contamination clothing neutralised it, diluted the result to many thousands to one, and flushed it away.

At the end of the day the bottle was only 50 cc and probably very little of that was actually hydrofluoric acid, but better to be safe than sorry.

[Manxmodder]

A while ago a mate and myself were clearing a workshop from a deceased estate. We were sorting useable materials and equipment from stuff that needed dumping when we spotted a plastic lab container with a yellow substance in.

A closer look revealed a faded label with Picric acid on it 

Picric acid is classed as a high explosive and it's another very dangerous compound to anyone unfamiliar with it's potential instability if it dries out or comes into contact with metals.

The explosives team were engaged to dispose of it safely.

I often wonder what potential outcome might have happened if someone else with no knowledge of Picric acid had won the bid for the workshop clearance.

 A Wikipedia page on Picric acid:
https://en.wikipedia.org/wiki/Picric_acid

....OZ.

[hermetic]

"I often wonder what potential outcome might have happened if someone else with no knowledge of Picric acid had won the bid for the workshop clearance."

Quite simple to answer your wonderings!

Boom!

Picric acid, and also organic peroxide (hardener for GRP resin) have a common feature, if they are stored with the lid slightly loose for long periods gasses evaporate from them, and crystallize round the gap in the bottle cap. unscrew the cap, shear the crystals and..........................BOOM! Also watch out for two pack car paint, some of which have the same problems, I had a near deaf experience with a plastic 5ltr can of discarded 2 pack.......................I still have tinnitus!

Phil

[raynerd]

 Sink with lots of water 

[awemawson]

Not when you are on a private sewage system that you own and maintain 

[raynerd]

   that would be a very valid point!