Aqua Regia method with 12-13% Ag

[giahylxag]

Hello everyone,
I own a pawn shop and recently learn gold refining as a hobby.
I am learning AR gold refining techniques but stumped on some problems, tried to crawl back and forth this forum but saw no definitive answers.
There are 2 questions that I want to ask:
A) Scap gold that has %Ag more than 10 but lower than 15
The prevailing market condition here is scrap gold that has Ag content about 12-13%. I read that 10% Ag is the maximum acceptable to go directly to AR . Is 13% too much to use AR method? If 13% Ag is not recommended, what is the proper method to deal with?



B) Gold loss
How much gold is loss given careful handling, lab grade acid/chemical and careful, standardized procedure. I mean "unavoidable/uneconomically recoverable" gold loss, not because you spilled some liquid here and there

 

[Yggdrasil]

Hello everyone,
I own a pawn shop and recently learn gold refining as a hobby.
I am learning AR gold refining techniques but stumped on some problems, tried to crawl back and forth this forum but saw no definitive answers.
There are 2 questions that I want to ask:
A) Scap gold that has %Ag more than 10 but lower than 15
The prevailing market condition here is scrap gold that has Ag content about 12-13%. I read that 10% Ag is the maximum acceptable to go directly to AR . Is 13% too much to use AR method? If 13% Ag is not recommended, what is the proper method to deal with?
View attachment 60705
View attachment 60706
View attachment 60709
B) Gold loss
How much gold is loss given careful handling, lab grade acid/chemical and careful, standardized procedure. I mean "unavoidable/uneconomically recoverable" gold loss, not because you spilled some liquid here and there

Welcome to us.
There are no sharp limit, it gets progressively harder to react all the Gold as the amount Silver Chloride increases.
With mechanical means (tumbling and so on) one can overcome much of it.
Anyway if you manage to dissolve all or nearly all the Gold there still will be various amounts held up in the AgCl either as liquid or particles.
Washing and secondary recovery from the converted Silver Chlorides is necessary.

 

[Yggdrasil]

Hello everyone,
I own a pawn shop and recently learn gold refining as a hobby.
I am learning AR gold refining techniques but stumped on some problems, tried to crawl back and forth this forum but saw no definitive answers.
There are 2 questions that I want to ask:
A) Scap gold that has %Ag more than 10 but lower than 15
The prevailing market condition here is scrap gold that has Ag content about 12-13%. I read that 10% Ag is the maximum acceptable to go directly to AR . Is 13% too much to use AR method? If 13% Ag is not recommended, what is the proper method to deal with?
View attachment 60705
View attachment 60706
View attachment 60709
B) Gold loss
How much gold is loss given careful handling, lab grade acid/chemical and careful, standardized procedure. I mean "unavoidable/uneconomically recoverable" gold loss, not because you spilled some liquid here and there

These links will be a good reading to gain more understanding in refining and recovery.

We ask our new members to do 3 things.
1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
It is free here on the forum: Screen Readable Copy of Hoke's Book
2. Then read the safety section of the forum: Safety
3. And then read about "Dealing with waste" in the forum: Dealing with Waste

Suggested reading: The Library

https://goldrefiningforum.com/threads/gold-refining-forum-rules.31182/

 

[nickvc]

Welcome to the forum.
As Yggdrasil stated if you go directly to AR with silver present in a higher percentage you will leave some gold in the silver chloride if you then run the converted silver through a cell that’s not too much of a problem as you can collect the gold from the slimes.
If you inquart your material with silver then you leave nothing behind in the chlorides as the silver will dissolve in the nitric and as a bonus so too will any PGMs if there in small quantities which again can be recovered from a silver cell.

 

[4metals]

I agree with Nick, inquart with Silver. In the pawn shop business you are getting your best profit margins from Gold and Silver. So you want those out first to get paid. By inquarting, which you can do with any sterling silver you buy, you can get all of the gold quickly and leave the Silver to recover either as a chloride or as cemented metal.

Typically jewelry has Platinum findings which hold the larger stones in place, before you melt those pieces it would be best if you could cut off those Platinum findings so you will maintain your Platinum much more concentrated. By doing this it is often possible to be left with a waste with little to no PGM’s to have to process later. Your Silver can be either cemented on copper if you want to set up a small Silver cell, or dropped as Silver Chloride to reduce to a metal and get 999 Silver (with a lot of rinsing). Either way you get your Gold and Silver quickly and that’s where you are making your money. As far as gold losses go, a small scale refiner can recover about 99.85% of the gold in the process. The balance, the few PPM that remain in solution or trapped in chlorides eventually are recovered when you process the stock pot or do a major cleanup.

The Platinum findings can be processed separately when you accumulate enough quantity.

Fortunately you are in the right place to be taught all of the required skills to do this right here on the forum.

 

[giahylxag]

Much appreciate your helps!

With mechanical means (tumbling and so on) one can overcome much of it.
Anyway if you manage to dissolve all or nearly all the Gold there still will be various amounts held up in the AgCl either as liquid or particles.
Washing and secondary recovery from the converted Silver Chlorides is necessary.

Companies like italimpianti use mechanical means (tumbling) to deal with high %Ag content, I am not sure how it works (physic and chemical). If I can't build a tumbler, simple stirring may help?

This refining system consists of a large PPl cylinder inclined to an angle of 25°, it continuously rotates by means of a special motor, with the possibility to adjust the rotation speed. The rotation forces the grains to rub against each other and consequently a rapid and effcient dissolution process is induced.

Welcome to the forum.
As Yggdrasil stated if you go directly to AR with silver present in a higher percentage you will leave some gold in the silver chloride if you then run the converted silver through a cell that’s not too much of a problem as you can collect the gold from the slimes.
If you inquart your material with silver then you leave nothing behind in the chlorides as the silver will dissolve in the nitric and as a bonus so too will any PGMs if there in small quantities which again can be recovered from a silver cell.

Sorry but this seems counter intuitive for me, if I begin with %Ag ~ 12% I think I have to inquart a lot of silver. Mechanical processes like tumbling or stirring (from italimpianti) help remove gold from silver cloride for not-so-high %Ag scrap in this case, should this be considered?

I agree with Nick, inquart with Silver. In the pawn shop business you are getting your best profit margins from Gold and Silver. So you want those out first to get paid. By inquarting, which you can do with any sterling silver you buy, you can get all of the gold quickly and leave the Silver to recover either as a chloride or as cemented metal.

My business mostly deals with gold with no silver, gold here comes at 15K minimum, I can say 60% of my stock is 15K gold with %Ag ~13%, 20% of my stock is 17K gold with %Ag ~8% and the rest is 999 gold.
If I have to inquart, I have to buy silver.
------------------------------------------------------------------------
So there are 2 options
1) To inquart and remove silver, I have to buy silver.
2) Go on AR but for sure some gold will be lost and we may recollect them in the waste

 

[giahylxag]

I am still thinking about gold loss. I can bear 0.5% loss unrecoverable.
Law of conservation of mass, if gold doesn't evaporate, it has to settle somewhere.
But I am thinking about "uneconomically recoverable" gold, some gold will be lost forever because the cost of retriving them is exceed its value.

 

[4metals]

Companies like italimpianti use mechanical means (tumbling) to deal with high %Ag content, I am not sure how it works (physic and chemical). If I can't build a tumbler, simple stirring may help?

The Italimpianti tumblers work when the Silver is as high as 12% from what I have experienced. The tumbling action provides a grinding of the work on itself to dislodge the encrusting chlorides. You would not get the same benefit with stirring.

So there are 2 options
1) To inquart and remove silver, I have to buy silver.
2) Go on AR but for sure some gold will be lost and we may recollect them in the waste

You may have to buy some silver to start inquarting or you can refine the gold you have with the high Silver and collect the chlorides to reduce them to silver metal. Once you have enough Silver refined this way you can perpetually inquart by recycling the Silver you recover from each lot.

One thing you can do to test this is to refine the karat with aqua regia, screen out the chlorides to collect them and take the chloride encrusted gold and put it in a screw top plastic bottle (large mouth) and shake it vigorously to break off the chlorides. Re-screen the loose chlorides and digest the balance in aqua regia. This will give you the mechanical breaking off of the encrusted chloride layers and can be repeated a few times. Next reduce the silver chloride with caustic and dextrose and melt it into a bar. Now take your XRF and measure the Gold content of the Silver bar. The gold in the Silver can exceed 1% and that will remain out of reach for you until you can process it in a Silver cell. The dollar value of the Gold trapped in the Silver can be had quickly if you had done the entire lot by inquarting with Silver first. This test will tell you if that step is worth it. Mechanically breaking off the Silver may seem like overkill but it will show you how much gold you are likely to trap with too much Silver in the feedstock.

In my opinion, inquarting will save you the cost of the tumbler plant from Italimpianti and, after you have your Silver reserve to constantly re-use to inquart, you will get all of your gold quickly and routinely collect the Silver in excess of what you have to recycle to inquart. In other words this can be a beaker refining operation (a 10 liter beaker should process 50 ounces of gold after leaching out the inquarted Silver, or 12 1/2 ounces of inquarted gold alloy). all without a large equipment purchase.

 

[4metals]

But I am thinking about "uneconomically recoverable" gold, some gold will be lost forever because the cost of retriving them is exceed its value.

the un-economically recoverable gold is usually trapped in ductwork and the seams of your hood from small spills. It represents less than 0.0005% of what you start with. The losses from testing and trapped in chlorides is easily recovered.

 

[4metals]

If you can do without all of the fancy valves and exhaust condenser, using a polypro cement mixer can give you the tumbling you need to break up some chlorides. You will need a speed controller to slow down the RPM of the tumbler.

 

[Anil]

Hello everyone,
I own a pawn shop and recently learn gold refining as a hobby.
I am learning AR gold refining techniques but stumped on some problems, tried to crawl back and forth this forum but saw no definitive answers.
There are 2 questions that I want to ask:
A) Scap gold that has %Ag more than 10 but lower than 15
The prevailing market condition here is scrap gold that has Ag content about 12-13%. I read that 10% Ag is the maximum acceptable to go directly to AR . Is 13% too much to use AR method? If 13% Ag is not recommended, what is the proper method to deal with?
View attachment 60705
View attachment 60706
View attachment 60709
B) Gold loss
How much gold is loss given careful handling, lab grade acid/chemical and careful, standardized procedure. I mean "unavoidable/uneconomically recoverable" gold loss, not because you spilled some liquid here and there

 

[Anil]

Ideally Silver less than 5% is fine with Aquregia method. More than that if you do not have a stirrer in the reaction vessel lot of gold will remain undissolved. One way to reduce silver is to add metal with less silver content thus decreasing silver mass by weight in the new alloy. The second way is to add copper to bring Au content to less than 37% and treat the alloy first with Nitric Acid to remove silver plus all base metal impurities. Once done, recover gold which is practically more than 99.90 % pure, and go through the aquaregia process to recover all gold of fine quality. The latest technology is to atomize the liquid alloy into very small fine particles and treat them with the Aquaregia process. Silver even up to 20% in Gold can be effectively treated without much loss. (99.90% recovery assured)

 

[Anil]

If you can do without all of the fancy valves and exhaust condenser, using a polypro cement mixer can give you the tumbling you need to break up some chlorides. You will need a speed controller to slow down the RPM of the tumbler.


View attachment 60745

 

[goldshark]

Ideally Silver less than 5% is fine with Aquregia method. More than that if you do not have a stirrer in the reaction vessel lot of gold will remain undissolved. One way to reduce silver is to add metal with less silver content thus decreasing silver mass by weight in the new alloy. The second way is to add copper to bring Au content to less than 37% and treat the alloy first with Nitric Acid to remove silver plus all base metal impurities. Once done, recover gold which is practically more than 99.90 % pure, and go through the aquaregia process to recover all gold of fine quality. The latest technology is to atomize the liquid alloy into very small fine particles and treat them with the Aquaregia process. Silver even up to 20% in Gold can be effectively treated without much loss. (99.90% recovery assured)

So, enquiring minds want to know; Do atomizers really atomize? What size variation do they actually produce? I have a couple ounces of 20 mesh Gold, assays 75% Au, 20% Ag, and 5% Cu. IF I was to go the AR method, would the alloy need to be tumbled, or is it fine enough in size to fully dissolve without agitation? Is there a chart somewhere, showing the percentage Au to Ag while including the mesh size of a certain alloy, where agitation is not required? I will more than likely in quart with Ag to the 75/25 ratio, when I decide to refine it. But still thought the particle size versus alloy percentage, and the need for tumbling/agitation, might make for some debate, not yet covered, as far as I know.

 

[Anil]

Tumblers inclined at 30 degrees are supplied by most refinery equipment manufacturers but depending on grain size and shape, 100% dissolution does not happen when silver content is more than 5%.

 

[andu]

This got so complicate looking so fast.
Process is simple you add enough silver so you have 6k gold , you melt pour into shot, do nitric boils till nitric comes clear, then you go AR add some sulfuric for any lead present, filter, add smb and let your gold settle.
https://www.youtube.com/@sreetips check this channel out


Make sure you rid of most nitric before going AR or you'll have problems with too much nitric.

 

[giahylxag]

Tumblers inclined at 30 degrees are supplied by most refinery equipment manufacturers but depending on grain size and shape, 100% dissolution does not happen when silver content is more than 5%.

I think secondary recovery is always needed. The question is economy. Given the market conditions I may usually get 12%Ag. I think inquarting approach first maybe more suitable, and AR if I want to refine further. Don't know much about gold loss.

 

[giahylxag]

This got so complicate looking so fast.
Process is simple you add enough silver so you have 6k gold , you melt pour into shot, do nitric boils till nitric comes clear, then you go AR add some sulfuric for any lead present, filter, add smb and let your gold settle.
https://www.youtube.com/@sreetips check this channel out


Make sure you rid of most nitric before going AR or you'll have problems with too much nitric.

Yeah I understand both inquarting and AR method but I got lost at 8:00, did he take to gold after he inquarted and used it in AR as secondary refine?

 

[giahylxag]

The Italimpianti tumblers work when the Silver is as high as 12% from what I have experienced. The tumbling action provides a grinding of the work on itself to dislodge the encrusting chlorides. You would not get the same benefit with stirring.


You may have to buy some silver to start inquarting or you can refine the gold you have with the high Silver and collect the chlorides to reduce them to silver metal. Once you have enough Silver refined this way you can perpetually inquart by recycling the Silver you recover from each lot.

One thing you can do to test this is to refine the karat with aqua regia, screen out the chlorides to collect them and take the chloride encrusted gold and put it in a screw top plastic bottle (large mouth) and shake it vigorously to break off the chlorides. Re-screen the loose chlorides and digest the balance in aqua regia. This will give you the mechanical breaking off of the encrusted chloride layers and can be repeated a few times. Next reduce the silver chloride with caustic and dextrose and melt it into a bar. Now take your XRF and measure the Gold content of the Silver bar. The gold in the Silver can exceed 1% and that will remain out of reach for you until you can process it in a Silver cell. The dollar value of the Gold trapped in the Silver can be had quickly if you had done the entire lot by inquarting with Silver first. This test will tell you if that step is worth it. Mechanically breaking off the Silver may seem like overkill but it will show you how much gold you are likely to trap with too much Silver in the feedstock.

In my opinion, inquarting will save you the cost of the tumbler plant from Italimpianti and, after you have your Silver reserve to constantly re-use to inquart, you will get all of your gold quickly and routinely collect the Silver in excess of what you have to recycle to inquart. In other words this can be a beaker refining operation (a 10 liter beaker should process 50 ounces of gold after leaching out the inquarted Silver, or 12 1/2 ounces of inquarted gold alloy). all without a large equipment purchase.

Thank you for such detail explanation. What is the cons of inquarting? Inquarting method seems much easier, faster?, and seems more economy to refine gold than AR method.
Given most fashion jewelry comes with low %Au and higher %Ag, why AR still widely used?
I opened this thread to ask about AR but this made me rethink my approach.

 

[nickvc]

In many Asian jewellery shops they use the inquart method only but it does depend what purity you want the fine gold to be.
For plated/fashion jewellery AR is not the method that most will use , cyanide can be used in some cases or a stripping cell.