Bedlasky - 9-8-2022 at 07:04
Hi.
My friend have a can with very potassium, probably without petroleum (according to the sound of can when he took it in his hands). What is the safest
way of disposal of this large amount of potassium? Throwing it in to the nearby small pond or stream sounds quite dangerous, because of explosion and
lots of KOH in water which can harm animals. Would be burning it in a pile of wood safer? Or did you have any better idea?
Loptr - 9-8-2022 at 10:24
How much potassium are we talking about? 100 grams? 1 kg?
Also, where are you located? There might be some people interested in possibly buying it.
Deathunter88 - 9-8-2022 at 10:52
Even without petroleum most of the potassium should still be good, since it forms an oxide skin that protects it from further reaction. I agree that
selling it is the best way, and failing that throwing it into a pond would be the second choice. Natural water sources are surprisingly well buffered
such that even a few kg of KOH should not harm anything. Burning is a bad idea because it will be hard to ensure all of it is reacted and next time it
rains there could be a fire.
unionised - 9-8-2022 at 11:00
An interesting potential problem with a fire is the possible presence of potassium superoxide/ peroxide.
That, soaked with the remains of the oil, or mixed with potassium metal ... might not be what you expected.
Selling it is good (using it for something would be even better- if you had a use for it).
Throwing it into a deep pond is probably the best option.
The official answer is to destroy it by covering it with kerosene and slowly adding a solution of alcohol in kerosene.
You then have to slowly add water to destroy the potassium alkoxides.
And then you have to get rid of lots of dirty kerosene.
A word of caution; I heard of someone disposing of waste sodium in this way (they lived on Jersey and threw it in the sea).
They were prosecuted for "dynamiting fish".
Bedlasky - 11-8-2022 at 09:27
Thanks for answers.
Do you think that 40-50 years old potassium would be still good? It was probably under petroleum most of the time, but who knows how long it is
without protection. Year? Decade?
Selling it to someone might be a good idea, but I think that sending it by post would be dangerous. Best would be personal handover, which make sense
just for someone near Czech/German/Polish borders.
Sulaiman - 11-8-2022 at 19:49
If it was mine, I'd first see if there is any usable potassium inside the crud.
If yes then recover it,
the crud will be a mixture of potassium metal, oxides, hydroxide and carbonate ;
so it should be an excellent dessicant,
Or, just leaving the crud exposed to the atmosphere (but no liquid water obviously) will eventually yield potassium carbonate solution - I think.
Texium - 11-8-2022 at 20:16
I would NOT endorse Sulaiman’s advice. Potassium in air, unlike sodium, forms primarily peroxide and superoxide rather than oxide, which leads to
old samples potentially being shock sensitive, especially if fresh metallic potassium comes in contact with the superoxide. I would hesitate to touch
it with a 10 ft pole, personally…
Sulaiman - 11-8-2022 at 20:21
Oh! that sounds bad... My bad!
Thank you for the warning/correction.
wg48temp9 - 12-8-2022 at 02:34
Back at a time when you could even by white phosphorous at the local chemical company. I had a ten+ year old bottle of sodium (a bit less than 500g in
a hydrocarbon. The sodium was heavily encrusted with a white partially translucent substance. I had read that there had been explosions when old
encrusted sodium was cut. So I decided to dispose of it. I drained the hydrocarbon and through it into a lake in a clay pit. No explosion but a lots
of bubbles reached the surface.
Tsjerk - 12-8-2022 at 04:30
To form sodium peroxides or super oxides you really have to mistreat the metal, but potassium not so much. Especially when stored under a flammable
solvent you don't want those oxides to decompose upon contact with the metal it is encrusting.
Bedlasky - 17-8-2022 at 13:30
Thanks for advice, potassium was safely destroyed in old petroleum barrel filled with water.