WD40_enjoyer
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Registered: 11-7-2025
Location: Sweden
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Mood: Extremely bored!!
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Extracting mercury from old batteries
Is there a way to get metallic mercury (or salt) in a reasonably pure form from batteries?
Wikipedia says it is HgO in the batteries aswell as some manganese dioxide and Zink. By that one could sudgest decomposition or some other process to
make a metallic form of mercury that is reasonably pure.
But are there risks of contamination from say Zink or some other component like the shell of the battery? For now this is the best method other then
old thermometers or barometers for me to get mercury. If there is another metod let me know!
professional chemical taster
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Radiums Lab
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Mood: Experiencing the elegance of science.
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Safely dissolve all batteries in HNO3. Don't come in contact with the solution. Add Hcl to the neutral solution to precipitate the HgCl2 and filter
it.
Soluable Hg salts are highly toxic so b very careful.
If you survive afer seperating the HgCl2 then I'll tell or well tell what to do.
I don't take any responsibility If you get injured or harmed or even ...
Good luck extracting it.
Water is dangerous if you don't know how to handle it, elemental fluorine (F₂) on the other hand is pretty tame if you know what you are doing.
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RU_KLO
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Location: Argentina
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It depends on the quantity of mercury in the cell.
"Mercury-containing button cells contain mercury in small amounts (typically 0.1-2%) and the purpose of mercury in the cell is to prevent the build-up
of hydrogen gas.
https://minamataconvention.org/sites/default/files/documents...
Its not much.
Like Radiums Lab said, dissolve everything in nitric acid. Filter insolubles. Adjust ph to neutral (more or less) then and some HCl drops (till no
more precipitate forms.
Mercury (if any) will be precipitated (as HgCl2).
MERCURY SALTS ARE POISONOUS. Use proper safety equipment.
Note: if there is silver and lead, they will also precipitate. - it seem that there is a silver oxide battery - Until 2004, all silver oxide batteries
contained up to 0.2% mercury) so try to find the datasheet of the battery if possible.
Go SAFE, because stupidity and bad Luck exist.
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Sulaiman
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Registered: 8-2-2015
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a colleague used to collect used silver-oxide button batteries to reclaim the silver for profit,
so if you can collect enough batteries to process for the mercury
(I guess more than 100g)
then you should be able to get a decent ammount of silver,
which has some interesting chemistry.
many silver-oxide batteries are 'mercury free'
I guess that silver-oxide batteries are a poor choice for mercury extraction.
PS although I have Hg I bought some cinnabar to roast the mercury out of it.
at least one batch of mine was fake and I got a refund so take care
but cinnabar is orderable and a small steel still is not complex.
I am having a couple of weeks holiday from being comfortably retired
so testing the other two batches will be quite delayed.
[Edited on 10-9-2025 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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