Help needed processing electrum

[shruli]

I 'm hoping someone can help as I have a dilemma processing some electrum.
I had a 120 grams of approximately 80% gold 20% silver. I melted & poured it to shot, put in outside in this rare UK nice weather, on heat in poor mans AR.
Started very well but then all the shot develops what appears to be an impregnable layer of silver & any reaction stops. I melted, poured & started again in fresh solution. Same thing but reaction stopped quicker. Thinking it might help I started again & added some 24ct gold to the solution. The gold reacted as expected but the electrum again coated itself in a protective layer of silver and stopped!
I have searched the forum & can't find a solution, so any suggestions will be appreciated. I am in the UK where nitric & sulphuric acid are not an option.
I have added a pic which looking closely shows the 24ct gold slowly bubbling away & the grey to the left doing nothing. Each time I start again the reaction slows down further as the percentage of silver goes up.
Many thanks
Keith

 

[Yggdrasil]

I 'm hoping someone can help as I have a dilemma processing some electrum.
I had a 120 grams of approximately 80% gold 20% silver. I melted & poured it to shot, put in outside in this rare UK nice weather, on heat in poor mans AR.
Started very well but then all the shot develops what appears to be an impregnable layer of silver & any reaction stops. I melted, poured & started again in fresh solution. Same thing but reaction stopped quicker. Thinking it might help I started again & added some 24ct gold to the solution. The gold reacted as expected but the electrum again coated itself in a protective layer of silver and stopped!
I have searched the forum & can't find a solution, so any suggestions will be appreciated. I am in the UK where nitric & sulphuric acid are not an option.
I have added a pic which looking closely shows the 24ct gold slowly bubbling away & the grey to the left doing nothing. Each time I start again the reaction slows down further as the percentage of silver goes up.
Many thanks
Keith

You need to increase the amount of Gold in the alloy, or inquart it and part it in Nitric.

 

[shruli]

You need to increase the amount of Gold in the alloy, or inquart it and part it in Nitric.

I think adding more gold will put me back to where I started so I can't see how that can help, unless I'm missing something?
As I said in post, nitric is not an option due to location. Thank you for your reply

 

[Yggdrasil]

I think adding more gold will put me back to where I started so I can't see how that can help, unless I'm missing something?
As I said in post, nitric is not an option due to location. Thank you for your reply

You need to have so much Gold that the Silver do not passivate the Gold. Or add sufficient Silver so the Gold do not protective the Silver.
25% Gold in the Silver is Gold, hence the term quartering or inquartering.
Or have so low Silver content that the SilverChloride formed do not passify the Gold.
I'm not sure of the ratio.

 

[shruli]

You need to have so much Gold that the Silver do not passivate the Gold. Or add sufficient Silver so the Gold do not protective the Silver.
25% Gold in the Silver is Gold, hence the term quartering or inquartering.
Or have so low Silver content that the SilverChloride formed do not passify the Gold.
I'm not sure of the ratio.

Many thanks. I will do some study on inquartering.

 

[FrugalRefiner]

The reaction stops because a layer of silver chloride has formed on the outside. You can rinse the shot and put it in ammonia which will dissolve the silver chloride. Rinse again and put it back in AR. Repeat as necessary till all is dissolved. Be sure to reacidify the ammonia solution promptly to avoid creating any explosive compounds.

Dave

 

[Shark]

Try using a glass stir rod and tap the silver so it falls off the gold. Or heat the solution using a stir bar type hot plate and stir bar. Otherwise Frugalrefiner and Yggdrasil both have sound advice.

 

[lazersteve]

Side note to having no access to sulfuric acid or nitric acid.

Sulfuric acid can be made quite easily by electrolysis of copper sulfate. If you don't want to deal with electrolysis setup then sodium bisulfate (swimming pool pH up) should be readily available anywhere pool supplies are sold and is well suited to manufacturer of nitric acid directly from the bisulfate salt.

Pretty much any nitrate (sodium, potassium, calcium, etc) can be used with the sodium bisulfate to make nitric acid. Distilled Nitric Acid is not a requirement for refining work.

If you are making poormans AR, then I assume you already have a source for nitrate salts. These are easily converted to a form that is suitable for inquarting.

Steve

 

[fiquett11]

I 'm hoping someone can help as I have a dilemma processing some electrum.
I had a 120 grams of approximately 80% gold 20% silver. I melted & poured it to shot, put in outside in this rare UK nice weather, on heat in poor mans AR.
Started very well but then all the shot develops what appears to be an impregnable layer of silver & any reaction stops. I melted, poured & started again in fresh solution. Same thing but reaction stopped quicker. Thinking it might help I started again & added some 24ct gold to the solution. The gold reacted as expected but the electrum again coated itself in a protective layer of silver and stopped!
I have searched the forum & can't find a solution, so any suggestions will be appreciated. I am in the UK where nitric & sulphuric acid are not an option.
I have added a pic which looking closely shows the 24ct gold slowly bubbling away & the grey to the left doing nothing. Each time I start again the reaction slows down further as the percentage of silver goes up.
Many thanks
Keith

Add distilled water in increments of 10z or less then that should have a little bit better results

 

[fiquett11]

1 oz sorry

 

[Yggdrasil]

Add distilled water in increments of 10z or less then that should have a little bit better results

His problem is the SilverChloride that forms in AR. This creates a coating that can not be penetrated by the AR.
Distille water will not alleviate anything.
Tumbling/stirring ie mechanical breaking the coating or alloying up with Gold or down with Silver works.
Or as suggested periodically removing the coating with Ammonia or other solvents work too.

 

[Ultrax]

If you don't want to use inquartation, you can dissolve your Au-Ag alloy electrochemically in the solution that will dissolve both metals in any proportion.
These properties have two classes of substances: cyanides and thiourea. Thiourea is better because it is much safer than AR or cyanide, and its saturated solution can hold up to 10 grams of gold and up to 40 grams of silver per liter.

Then, you can precipitate Au-Ag metals as hydroxides by NaOH, or as a sponge by electrowinning, or even use cementation with aluminum powder, and divide the precipitate in the usual acidic way easily in one or two simple steps.