AP and Silver

[yar]

I mixed a fresh solution of Ap, 100 ml hcl and 50 ml h2o2, and put one silver plated buss bar into solution. Within 24 hrs the bar was completely stripped of Ag which at first was in flake form and then formed AgCl. I believe this occurred due to it being a fresh batch of AP. The AgCl settled to bottom of beaker under the AP.

After reading the thread on conversion of Agcl via NaOH and Karo, I am going to follow lazersteves direction in that thread to convert over to AgO. My question before starting is once I decant the AP should I rinse the AgCl until all AP is washed out and then procede with attempting to convert to AgO? My instinct tells me to wash it to remove as much excess chlorides and base metals as possible before adding the NaOH.

I hope I am heading down the right path here, but either way it has been fun no matter what the outcome and is a good learning experience for me.

 

[yar]

As a thought, instead of cutting the bar in half, you might try scoring it with a utility knife (just the surface layer, you don't need to go very deep) into sub-cm-square regions. That would give the AP more access to release the silver, without needing to dissolve quite so much of the copper to accomplish the task.

Depending on the process used to make the bar and the thickness of the silver plate, you might also find you can just peel the silver off. If the manufacturer just cold-dipped it without bothering to chemically bond the two layers, you may have something not all that dissimilar from peeling a chocolate coin.

Yes I did score each side of the buss bar and after it was stripped there was a nice piece of clean copper left, which I was hoping for. The contact did not come off which I did not think it would since I believe it is brazed on.

I also tried to peel away the plating but that did not work. I appreciate the input, thank you.

 

[niteliteone]

The AgCl (?) needs to be rinsed until clean. Also check the filter trash for silver flakes.

I'm not sure what you have, but that is how I would deal with it. Also their is a way to test the silver chloride to verify that is, what it is.
It involves dissolving the chloride in NaOH and then re-acidifying it back to silver chloride. A little searching will help you find a thread that explains the process completely.

 

[Richard NL]

Silver chloride AgCl is fairly insoluble in water but if we heated it strongly in salt water NaCl (concentrating the solution) we can put some of the silver into the salt solution as silver dichloride soluble in the concentrated brine solution, upon dilution we would again get the insoluble white silver chloride {AgCl2 + H2O --> AgCl + Cl- + H2O} this is the similar to how we get a little silver in our aqua regia solutions.
AgCl + Cl- --> AgCl2

Thanks butcher,
The amount of chloride present in water can be determined by adding a silver nitrate solution to the water, →Parts per million/micrograms per liter←.
Because it is pushed out of the solution.

Still there can be silver in aqua regia, and it is normally loaded with chlorides.
This was a mystery for my!
Thank you sir, for making that clear.

Please correct me if I'm wrong or made a mistake,i am still learning.
Best regards Richard.

 

[butcher]

Richard NL,
It sounds like you understand it very well.

 

[Pantherlikher]

A bit odd in thinking or novice in question.
Silver plated copper in fresh AP may disolve some silver and then drop as AP gets running.
After all silver is stripped off; Decant, water washes untill clear. Would running fresh HCL with a few drops of well used AP finish dissolving any copper left behind or would it go for Silver or do nothing?.

Also how about the silver plated nickle pieces. (newbie question) as it would pertain to silver plated.

Then there is the steel arms with copper then silver plated buttons.

Individually, this is definately not worth any major effort but things to ponder and would be nice to be in the same thread since we're here.

B.S.

 

[butcher]

Silver really does not dissolve well in the (AP) copper II chloride solution, if the silver is very thin, or powders, you can get more of it converted to silver chlorides, but thicker silver parts just coat over with that silver chloride crust which protects the silver metal underneath the, basically silver is not easy to work with in a chloride solution, because of the passivisation of the silver metal.

As a way to remove silver in contact points, where I cannot cut away or de-braze all of the copper from the silver contact, and to save my nitric acid, I found I can dissolve both the copper and the silver (Or at least break the silver down to chlorides) in a solution of copper and iron chlorides (that old used AP solution).
I have found boiling hot solutions of concentrating iron chloride works well to dissolve copper and silver into solution, the hot concentrated High chloride solution with the agitation,will attack both copper and silver fairly well, and both copper I chloride, and silver chloride will precipitate as white powders when the cooled solution is diluted, HCl will dissolve the copper I chloride forming copper II chloride, leaving the silver chloride.

But as with most chemistry we do here, unless we dissolve all of the base metal involved, the more noble metal can plate onto or stick to the base metal, with plated spoons you have an awful lot of base metal to put into solution to recover a very tiny amount of silver from that spoon.

Also spoons or silver plated flat ware, can be made out of several base metals (normally to make the brass under the silver plating look white like silver), these other metals like zinc can push acids out of solution, or push metals out of your leach solution, basically making the leach ineffective where the spent leach will need replacing with a more fresh leach (copper/ iron chloride leach)to continue the operation...

 

[BSGMiner]

Well, here's this weekend's attempt at adding 400ml of HCl + H2O2 to my accumulated mixture of silver & base metals, which I tried out my air bubbler on as well.


Is it usually that dark of an emerald green? What does that indicate?

In addition, I tried out a small crockpot to help evaporate a diluted HCl + base metals solution. Now that it's starting to cool, I can see a thin layer of whitish precipitate (Copper I Chloride?) in the bottom of the jar.

 

[BSGMiner]

Well, here's this weekend's attempt at adding 400ml of HCl + H2O2 to my accumulated mixture of silver & base metals, which I tried out my air bubbler on as well.

Notice: Don't post right before midnight, or it won't show up in the New Posts section when everyone wakes up...

 

[butcher]

The first picture we can see lots of iron oxides and or hydroxides in the stockpot.

The next picture of the darker solution, HCl, and oxygen will put iron and copper (as well as most base metals) into solution, the dark green comes from being saturated with iron and copper chlorides in solution (in a lower oxidation state) as CuCl and FeCl2, instead of the lighter green of CuCl2 and FeCl3, the bulk of white salts are most likely CuCl. (Rejuvenating your leach at this point with oxygen and a little HCl will put more of the white insoluble CuCl back into solution as CuCl2) and as the darker CuCl2/CuClsaturated solution oxidizes the CuCl into CuCl2 the solution will get a lighter green color (like the lower picture).

The light green solution looks to be more CuCl2, ready to dissolve more copper iron or base metals,
The white salts can be:

Lead chloride.
fairly insoluble in HCl or CuCl2 solution, but it dissolves in boiling hot water and will precipitate back out when wash water is cooled.

Copper I chloride.
Dissolves in HCl.

Silver Chloride.
insoluble in HCl or CuCL2 solution, insoluble in hot or cold water.
silver chloride is a very fluffy and light, so it can take some time to settle while dissolving the lead chloride above in hot water, so we need to let the fluffy silver chloride settle while keeping the solution very hot while dissolving the lead chloride, before decanting the lead chloride solution from the solids...
We could dissolve the silver chloride if we wished, (although I do not see any reason in this case), using ammonia which if not properly done (acidified) can make an explosive silver compound, or with sodium thiosulfate...

And any noble metal like gold.
Noble metals which will be insoluble in the CuCl2 solution or will not dissolve in hot water, will not dissolve in HCl...

 

[BSGMiner]

The first picture we can see lots of iron oxides and or hydroxides in the stockpot.

The next picture of the darker solution, HCl, and oxygen will put iron and copper (as well as most base metals) into solution...

The light green solution looks to be more CuCl2, ready to dissolve more copper iron or base metals...

Thanks for your assessment and suggestions.

I'm bubbling the first two jars again today to see if I can get some more of the precipitate to dissolve into solution.

 

[BSGMiner]

Well, here's what I've been busy doing-->and the results:
1) Adding 100mL HCl into the copper chloride & bubbling some more air into both jars-->No noticeable difference
2) Evaporating my stock pot-->Resulting in an inch of copper and iron salts
3) Decanting my copper chloride from the silver jar-->400mL total
4) Using a $5 battery acid tester in my copper chloride-->1.1 specific gravity
5) Pouring the copper chloride into the stock pot remnants-->it dissolved it all and resulted in a 1.2 specific gravity