Thoughts on forcing corrosion of sterling silver to refine?

[ORCB]

Hi guys,

I figure that the expertise here can save me time and money. I'm full of green ideas that I might as well start bouncing out there to accelerate my education. Figure someone would have done this or know a problem with it.

My thought is to use electrolysis with the sterling object as the anode, in a vessel of salt water, to force corrosion of the object into silver chloride and copper chloride. Done this to some extent and it appears from my limited knowledge of chemistry and looking at the reaction that this is what's happening. I think hydrogen gas is bubbling off the cathode. I think most of the chloride ions are reacting with the silver and copper to make their chlorides. Sodium ion does nothing. I'm pretty sure it's getting more basic as hydroxide ions build up after losing their hydrogens to the cathode.

The sterling object just sort of disentigrates into powder slowly and sloughs off layers of the chorides. To me, this seems great, cause I'm breaking down the object and now there's something to work with, with only electricity and salt water.

For the next step, I was thinking of dissolving copper chloride into ammonia and then you're left with silver chloride, insoluable in ammonia, and then, boom, you've got your silver chloride to turn back into pure silver. I also read that silver chloride reverts to silver metal under light, and releases the toxic chlorine gas. There also is the potential to separate based on their densities.

Thoughts?
Thanks

 

[goldsilverpro]

Silver chloride is soluble in ammonia. The whole thing sounds a bit cheesy to me. What do you ultimately want to accomplish?

 

[ORCB]

Well, I guess the appeal for me is to use the cheapest and least noxious materials and methods possible. I'm also just curious. It does sound cheesy, I admit, but whether or not it is cheesy I don't know.

 

[kadriver]

If you try this experiment, then I would be interested in your hearing about your results.

 

[4metals]

The chloride in the salt water will cause the sterling bar to crust over quickly and passivate in solution. Silver as low as 10% in gold alloy crusts over and stops the aqua regia reaction, 90+% of silver would be impenetrable save for a surface crust.

Silver coins from shipwrecks spent hundreds of years on the bottom exposed to salt water and aside from a surface crust are still in their original shape.

 

[ORCB]

The chloride in the salt water will cause the sterling bar to crust over quickly and passivate in solution. Silver as low as 10% in gold alloy crusts over and stops the aqua regia reaction, 90+% of silver would be impenetrable save for a surface crust.

Silver coins from shipwrecks spent hundreds of years on the bottom exposed to salt water and aside from a surface crust are still in their original shape.

This is dead on. I had a feeling this could be the biggest hurdle. I've only experimented with one 15 gram sterling spoon and two D batteries in series for the power source, taped together with duct tape. I didn't fully corrode the entire object down to powder, and besides the lack of amps, the crust you mention was probably inhibiting the reaction. A few times I pulled the spoon out and rubbed off a layer of nasty chloride skin quite easily with my fingers, and it slides right off, but obviously you wouldn't want to be doing this on a large scale, stopping to rub off layers of corrosion in order to expose the sterling underneath. With that power source I took off about 1.5 grams in four hours, before stopping it because I determined I needed a variable DC power supply.

Another thing worth mentioning is that there was some effect where the corroded skin would start to blister off by itself slowly. It looked like paint blistering in heat. So there is some tendency to detach from the object, but probably not enough by itself... except maybe under the perfect conditions with a maximum material thickness.

If I find out more I'll post it. Thanks for the input!

 

[ORCB]

I guess it has to do with the intermolecular forces bonding the silver atoms to the object, and also the silver/copper chloride molecules, as regards their tendency to stick on the object and create an impenetrable layer. Definitely, some of the silver/copper molecules came off on their own and clouded the water until they settled, but all the variables which affect this, I don't know. Maybe with the proper voltage/amp settings, you could maximize the tendency of the newly created silver/copper chlorides to detach themselves from the spoon and just sort of drift off. Interesting. This could probably be used to strip off silver plating quite effectively. The impenetrable crust might then even become an advantage to stop the reaction just when the layer of silver had reacted.

 

[4metals]

If you had a plating barrel which tumbles, you could cast sterling balls and tumble them to constantly abrade off the silver chloride. Then the skin effect would constantly be "peeled off" exposing fresh silver and copper and chlorides would accumulate like snow on the bottom. You still have to address separating the different metal chloride species.

 

[Anonymous]

My anticipation is to use electrolysis with the admirable as the anode, in a barge of alkali water, to force bane of the object into argent chloride and chestnut chloride. Done this to some measurement and it appears from my bound ability of allure and searching at the acknowledgment that this is what's happening. I anticipate hydrogen gas is bubbles off the cathode.

 

[4metals]

I'm not following you, your English, while impeccable, leads me to think I'm speaking to the King of England!

Please re-phrase your question, I am but a commoner.

 

[HAuCl4]

I'm not following you, your English, while impeccable, leads me to think I'm speaking to the King of England!

Please re-phrase your question, I am but a commoner.

I think he could be James Bond's brother. :lol:

 

[Barren Realms 007]

I'm not following you, your English, while impeccable, leads me to think I'm speaking to the King of England!

Please re-phrase your question, I am but a commoner.

I think it is the type of translator he is using.

 

[Drewbie]

Yep

Argent chloride = silver chloride
Chestnut chloride = copper chloride
barge = vessel

etc etc