AP process and silver

[PMMarine0311]

Is there a way to reclaim any silver that may have dissolved into my AP solution

 

[FrugalRefiner]

AP is a chloride solution. There will be no silver dissolved in it.

Dave

 

[PMMarine0311]

Ok thank you.

 

[butcher]

I agree with FrugalRefiner silver, in the way we normally use the Copper II chloride leach silver will not normally dissolve, it is oxidized to silver chloride, which is insoluble in water HCl or nitric acid, and CuCl2 solution. If the silver is not in fine powders or it has any thickness or mass at all the silver builds an oxidized coating of AgCl which passivates the silver with the protective crust of silver chloride protecting the silver metal under that passive layer of AgCl from reacting with acid or being attacked by the CuCl2.


With that said, silver chloride is soluble in chloride solutions. This is not a contradiction of facts, just like how many metals are insoluble as hydroxides but can become soluble in an excess of that base, chemistry has its quirks.

I can slowly dissolve silver in used copper II chloride (especially if it also contains ferric chloride FeCL3) or is a mixture of the two which is normally the case with my well used and reused "acid peroxide solution" (that most people would say was spent and would recover copper and then treat it as waste).

Ferric chloride is a fairly good etching solution for silver metal, (copper II chloride will work also to etch silver just not quite as well as FeCl3). When heated and concentrated the FeCl3/CuCl2 which becomes more like FeCl3 and CuCl3 {FeCl3+ FeCl2 +CuCl2 + CuCl and some other base metals (aq)} the heated solution the salts in solution concentrate forming a high chloride solution. t

This dissolves the AgCl forming a soluble compound in the hot concentrated chloride solution as AgCl2, AgCl3 and possibly AgCl4, upon cooling and then dilution I get a precipitant of CuCl and AgCl.

The powders of CuCl and AgCl are then dissolved in diluted HCl which puts the CuCl back into solution as CuCl2 (which can be reused as a fairly pure CuCl2 etching solution).

Leaving me with mostly AgCl powders and some CuCl, this impure silver chloride is then reduced to silver (a little copper, I do not try to wash all of the CuCl out, as that just uses more HCl (than I care to use, and one of the main goals for me here is to reduce the volume of the chloride solutions I had anyway).

This impure silver chloride is then reduced to silver metal powders (a little copper is also reduced, with H2SO4 and pieces of iron metal, and after a few water washes this gives me a silver metal when melted. (everything is reused nothing here is waste to me) even the ferrous sulfate is reused elsewhere.

I have been using this to de-plate silver plating , from electrical copper buss bars and contact points. it is a slow process, I run a hotplate almost constantly doing this, for one I reduce the volumes of my copper/iron solutions (used AP volumes) and reuse what would normally be considered a waste product, and get a little silver to boot.
Ag + CuCl2 ---> AgCl (coating) on Ag + CuCl
Ag + FeCl3 --> AgCl + FeCl2
AgCl(s) + Cl --Hot Conc.---> AgCl2(aq)



The solubility of silver chloride in hot concentrated saltwater brine, in 26% NaCl sodium chloride solution, at 212 degrees F. it will dissolve about 4.5 grams of silver chloride as AgCl2, AgCl3, in 1000 grams of this hot brine solution.

I do not have the data on how much silver chloride is dissolved in Hot concentrated ferric /cupric--cuprous chloride solutions but I would guess it is probably fairly close to the salt water solution shown above. I just know it holds a heck of a lot of silver in solution when it is hot and concentrated....

I Have also been looking into using ferric nitrate as an etch to recover silver.
Ag + Fe(NO3)3 <---> AgNO3 + Fe(NO3)2
Hot concentrated the reaction moves towards the right. Cold and dilute the reaction moves towards the left.
I still need to work out some problems of this idea, before I begin to start experimenting with it.

 

[Grelko]

It's great when butcher stops by to tell a story I always learn something.

 

[Topher_osAUrus]

:mrgreen:
I was thinking that same thing.

The salt water hot brine is very interesting to me.
I think I would rather use that than ammonia. The ammonia I have been using has some additive (the bottle doesnt say it does..but..) and it, even after reacidifying, has big soap like bubbles that can form on stirring. It hasn't had any ill effects, as I can tell, but, it's still better to remove as many variables as possible.

Butcher, are you trying this out on any silver plate? Or have your tests been primarily with silver plate bussbars/contact points?

 

[butcher]

Yes, I use it on copper with silver plating, On thick buss bars it takes off the silver (some brushing and changing of solution during the process.

Sometimes I may use an NH4OH wash, these are rarely needed, but sometimes I will use one if the silver chloride crusts up on materials during the process, this same wash solution is reused with small additions of fresh ammonia until you I am done) and the silver is recovered from the compound with HCl acid (remember never let this solution dry before recovering the silver (the explosive silver fumilate could form when dried...

The thick copper buss bars de-plate with not too much of the copper being dissolved, with thinner pieces I just put both copper and silver into solution and recover both the silver and copper later.

Brass with silver plating works also, but I keep the brass and copper separated in different solutions or batches (the zinc jacks around with being able to reuse the solutions, so brass is done with waste I will not reuse much more before recovering copper and treating the solution for waste...

The process is simple but would be very hard for me to describe.


I also use this process in combination with a copper cell using copper sulfate electrolyte as a different process but it kind of ties in with this process for recovery of silver and the copper cathodes that can be sold.
Brass with silver plating works also but I keep the brass and copper separated in different solutions or batches.

Just put a corning ware dish on a hot plate (which sits on a fiberglass cafeteria tray to catch small spills or drips). Add your used copper/iron chloride solution and some plated silver objects (after burning the oils off them). Turn the heat to high (I back it off full high a little, I just think that may make my burners last a little longer), and go do something else as the solution concentrates.

Check on it after several hours and add more solution to keep objects covered. after solution begins to form crystals while solution is still hot take your suction bulb syringe and transfer the solution to a mason jar (add some more of the solution you wish to concentrate.
In the mason jar upon cooling some AgCl and CuCl falls out of solution. Return that concentrated liquid solution back to the heated corning dish, keep repeating this until you have a lot of white powders in the mason jar and your finished de-plating your silver objects.

(Note if the silver in the solution gets too saturated of silver that it begins to re-plate the copper I will dilute it some to drop out some of the silver before returning the liquid).

When done the solution is then diluted and large amounts of CuCl and AgCl precipitate (then we rinse the white powders with water to dissolve water-soluble salts.
(these white powders can be saved under a little water, in the sun the white powders may darken to gray or black of dark purple because of the silver, the powders can be saved until you need them later, where it can be used to make up a fresh batch CuCl2 with HCl addition and you can recover the silver then).

The diluted HCl puts CuCl back into solution as CuCl2, the AgCl is left insoluble as white powders (after rinsed they will darken in sunlight).

The silver chloride can be converted to silver metal powders, I use the H2SO4 iron method because I have some residual CuCl which also converts to copper in that process (Karo Hydroxide methods does not work as well unless you remove most all of the CuCl,which I do not because I want to keep my solutions to a minimum) and I do not worry about haveing some copper in the silver (i am using the silver in other processes anyway).

There is a little more to it but nothing you can not figure out if you try it out.
Just try it next time you have a bunch of waste Copper/iron chloride to deal with and see how it works.

I have made a post with a lot of the details on the chemistry and how this works describing rejuvenating the solution....
search for reusing your old copper/iron chloride solution...

 

[Topher_osAUrus]

Beautifully described butcher.

You are a wealth of knowledge.

I have read many of your copper/and iron chloride leach posts. But I just had to ask on how viable of an option it is for silverplate...i have a bunch lying around and I have been kicking ideas around. Was just curious if you had discovered the holy grail of silverplate recovery. I will give it a test in a couple of weeks, after we get settled in to our new home.

Until then...I have some reading to do.

Thanks again butcher.

 

[butcher]

Don't expect miracles silver and copper are just too close together in series and copper is a bit more reactive.

 

[Geo]

I found that silver chloride will slowly dissolve in concentrated nitric acid over time. It's just an observation.

 

[UncleBenBen]

I found that silver chloride will slowly dissolve in concentrated nitric acid over time. It's just an observation.

I think I remember reading that sunlight converts silver chloride to oxide as it darkens. Could light be converting it to silver oxide, then dissolving?

 

[Geo]

I found that silver chloride will slowly dissolve in concentrated nitric acid over time. It's just an observation.

I think I remember reading that sunlight converts silver chloride to oxide as it darkens. Could light be converting it to silver oxide, then dissolving?

I don't think so. It happens much faster than that would take. As an experiment, take a small sample of silver nitrate that has excess nitric acid and treat it as a PM test in a spot plate or plastic spoon. Add a drop of stannous chloride. The silver will immediately precipitate. Leave the test to sit for a few hours. When you check the sample later, the silver chloride will have redissolved. Addition of more stannous chloride will have the same effect over and over until the excess nitric acid is depleted and the silver chloride will stay as a solid.

 

[UncleBenBen]

Well this has my curiosity going! I'll have a go at it next chance I get. Pretty sure I've got enough nitric left for a few more small tests.

Thanks Geo, this should be a fun one!

 

[butcher]

Silver chloride in sunlight through solar radiation, or light energy which moves electrons this energy moving those electrons convert silver chloride to elemental silver metal and chlorine. If the silver chloride was in a sealed vessel with hydrogen the sun would very slowly convert silver chloride to elemental silver and hydrochloric acid.

Pure hydrogen and chlorine gas, when mixed in sunlight can explode into HCl acid but you will not have to worry about that here.

Silver chloride is a fluffy salt clumps and the light basically is just converting the outer layer of these clumps of silver salt to metal, the silver chloride inside is still basically a silver salt with an outer coating of silver metal shell, it would not really be a good way to reduce silver chloride to metal as it would take a long time and you would have to spread the powder out thin to expose it to light with possibly grinding to keep exposing more of the salt to the light...

These principles are what was used in photography

 

[Barren Realms 007]

Silver chloride in sunlight through solar radiation, or light energy which moves electrons this energy moving those electrons convert silver chloride to elemental silver metal and chlorine. If the silver chloride was in a sealed vessel with hydrogen the sun would very slowly convert silver chloride to elemental silver and hydrochloric acid.

Pure hydrogen and chlorine gas, when mixed in sunlight can explode into HCl acid but you will not have to worry about that here.

Silver chloride is a fluffy salt clumps and the light basically is just converting the outer layer of these clumps of silver salt to metal, the silver chloride inside is still basically a silver salt with an outer coating of silver metal shell, it would not really be a good way to reduce silver chloride to metal as it would take a long time and you would have to spread the powder out thin to expose it to light with possibly grinding to keep exposing more of the salt to the light...

These principles are what was used in photography

Set it up on a stir plate and let nature takes it course.