Too much hydroxides

[Bluebloomer]

Hi all, been collecting waste over time, and now I have this 10 L bucket filled with a mixture of copper and iron hydroxide, possibly some aluminum and nickel too.

It won't settle much, and I'm not sure what to do next. Would it be a good idea to acidify the liquid, to a PH of 2 then cement copper out with iron, and does that even work with iron already mixed in with the hydroxides ?

The source of all this are some experiments gone wrong, and the waste from dissolving 2,8 KG of Dutch silver coins (78% Ag). There should be over a pound of copper inside.

I would like to recover as much copper as possible, and I can safely discard the remaining metals.
Any help would be greatly apreciated as we go in to winter, and I need to get rid of the waste buckets outside before it starts freezing.

Thanks !

 

[Geo]

Actually, you should have removed the copper first. HCl would probably be your best bet. I don't think the PH has to be that low. Just keep adding the HCl in increments small enough that it doesn't boil over. There will be a strong reaction as you add the HCl. Add slowly and keep a check on the temperature as it is sure to rise. You may want to do it over the course of the day. The copper will cement out on steel. No need to use anything exotic or fancy, just scrap steel that is not painted or galvanized. Galvanized will work if no other source is available but it just adds more toxic metals to the mix.

 

[Bluebloomer]

Thank you, Geo. And yes you are right, I should of cement the copper before, but that was before I tried to understand what the heck I was doing... I was basicly just messing around, wasting acids, and even precious metals... It would of been a better idea to treat the waste from the coins seperatly but I mixed it all together.

I now have 4 buckets with a rusty brownish solution, with a PH between 2 and 3.5. I will let it rest for a while then add some clean steel.

Should a bubbler be introduced ?

 

[4metals]

If you have iron hydroxides you have to get the pH down to put the iron in solution rather than in suspension. If you add steel now copper will come down but iron hydroxide may form too and you will end up with a mix of the two.
Lower the pH until the liquid is clear ( maybe you will not be able to see through it but by clear I mean all particulates dissolved) then add iron to drop the copper. An air bubbler will speed the process up.


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[Geo]

LOL, I only posted half of what I should have. It was four in the morning and I was about half asleep. I meant to say to keep adding the HCl until the solution goes clear. Some help I was. Thanks 4metals for saving the day.

 

[Bluebloomer]

Thank you guys for the additional information.

I took out the iron earlier, rinsed it with clean water and collected it in a flask.
Most of the copper (bright red) is settling on the bottom, but a lot of very fine particles are floating in the flask and they won't seem to settle. They are suspended in the solution. The PH is around 6.5

Will those fine particles settle eventualy, or do I have to make a PH adjustment ?

And to clarify; I had a lot of different liquids and waste collected from the time I just didn't know what I was doing or how to treat waste properly. I added it all in 1 60 L bucket, and added HCL until a PH of 2.5 and near all solids dissolved. It's hard to see anything because of all the rust, ( I assume it is rust) the liquid has a mustard like color, but it has no particles.

I added perforated steel mesh (3mm) and a bubbler, a barbell weight, and a 8 mm thick piece of clean steel and let it bubble during the day, and switch of the pump at night. (No power outside, and it's too cold to leave the door open.. ) and resume in the morning. Did a test with 1 litre of the solution to neutralize and added much water and the precipitate was near black and settles quicly. Those are the remaining base metals I assume.