Wash off the silver coating in concentrated sulfuric acid.

[anarxi]

used:
2 glasses with a capacity of 1 liter.
700 milliliters sulfuric acid 92%
80 milliliters nitric acid 58%
Tap water for rinsing: about 15 liters.

base material
copper, brass, bronze with silver plating.

 

[4metals]

OK you have created a pretty strong solution that effectively and selectively will strip Silver plating. Now how are you recovering the Silver from the solution? Half of a solution to a problem is as bad as no solution.

 

[anarxi]

OK you have created a pretty strong solution that effectively and selectively will strip Silver plating. Now how are you recovering the Silver from the solution? Half of a solution to a problem is as bad as no solution.

Well, I didn't create it.
This is an old classic solution from the beginning of the last century.
at least.
in the classics, for 19 parts of sulfuric acid there is 1 part of nitric acid.
transformation of silver through chloride.
the solution (a mixture of acids + dissolved metals, silver and tin, zinc, possibly bismuth) is simply poured into salt water.
I pour it into a canister containing water from previous work.
through the neck into which the watering can is inserted.
sulfuric acid and water, as you know, behave violently when combined.
you need a gas mask (or goggles and a respirator) and rubber, durable gloves.

 

[4metals]

you need a gas mask (or goggles and a respirator) and rubber, durable gloves.

Thank you for highlighting this. It is exactly why I never recommend the method.

 

[Dreamer]

Seems like an expensive way to to recover from plate. I suppose in a perfect world it would saturate at about 80 grams of Ag. Do you know what your yields have been from a saturated solution over time?

 

[anarxi]

Although the gingerbread is unsightly in appearance, the dough turned out good.

 

[anarxi]

Seems like an expensive way to to recover from plate. I suppose in a perfect world it would saturate at about 80 grams of Ag. Do you know what your yields have been from a saturated solution over time?

This solution can hold up to 300 grams of silver/1 liter.
in an ideal world...
there will actually be sulfite, which will take a lot of hot water to dissolve

 

[Dreamer]

Fantastic results! Is this the process where the base metal passivates once the silver is digested or do you have to do careful watching?

 

[snoman701]

Looks like you had quite a few silver contacts in that mix. A majority of that silver was probably from those.

 

[snoman701]

If you just added the nitrosulfuric acid directly to a small volume of saturated sodium chloride water essentially precipitating all of the silver as chloride with a minimal volume of water, would it not settle out due to the viscosity of the mostly concentrated acid? Thus allowing the sulfuric acid to be reused a couple of times before it becomes too dilute to passivate the Cu??

 

[anarxi]

Looks like you had quite a few silver contacts in that mix. A majority of that silver was probably from those.

no, there was not a single silver contact there.
there were only silver plated parts..
The scheme of work is as follows:
Since there was a lot of raw materials (by volume), I divided it into 3 parts.
the first part is poured into a glass and filled with sulfuric acid, put on heat to start the reaction. (ambient temperature was about 12 degrees Celsius, autumn)
add the first 50 ml of nitric acid...
I stirred the material in the glass several times for better contact with the acid.
Apart from a slight white haze over the glass when I removed the lid, there were no visible signs of a reaction.
in 20 minutes the process was completed.
the liquid was poured into another glass, into which the second part of the material had already been poured.
The material from the first glass is poured onto a sieve and washed with water.
The rinse water immediately drips into a bucket containing salt water, where it turns into silver chloride.
the third part of the material is poured into the first glass.
The second wash lasts a little longer.
the third is even longer and so on....
if you have a lot of prepared raw materials at once, such transfusions can be continued.
adding nitric acid.
Over time, when saturated with silver, the solution thickens and silver sulfite accumulates in it.
then it is poured into a separate container and allowed to stand for 12-14 hours.
All the sulfite (and debris) settles to the bottom.
the liquid part is decanted, diluted with fresh sulfuric acid and the process can be continued again.