For the LIFE of me I cannot get my gold to drop! 😭

[OldManSam]

Here's the situation ... I am not allowed (by the wife) to work with Nitric at home, so I am stuck using Sodium Nitrate to make poormans. I used this to dissolve about 22 grams of 8.5k gold in my fume hood, as one does, and had no problems doing so. Afterwards I discovered I had used too much NaNO3 and so I needed to denox. My solution was hot so I added sulfamic crystals and set my stir bar spinning.

After the sulfamic had dissolved I added a little more for good measure and eventually saturated the solution 😅 ... oops. At this point I needed to filter it to get the lead and excess sulfamic out anyway, so I did so. Afterwards I added some tap water ice to cool it down for precipitation...

Stannous test turned nice and black ... soooooo ... added SMB. Crazy foam but no precipitation. Thinking I was crazy I added more SMB but same result. I let it sit for several hours ... but nothing. Not even a dusting. Bear in mind I am expecting almost 9 grams of 24k, so to see nothing at all is unnerving.

Can anybody look at my process and let me know what I did wrong? Too much sulfamic? The tap water ice? For the life of me I don't think there is excess nitric in solution. Fresh stannous solution, too ... Is it possible I have pt group metals that I am confusing in the stannous test??? 😭

 

[Ultrax]

Read my post If SMB is over-poured... maybe it will be useful.

Apparently, your only option now is to evaporate the solution to dryness and calcinate the precipitate at 600^oC-800^oC. Then re-dissolve.
Or use peroxide 65%, it also oxidizes gold SO-complexes to metal. Lower concentration won't precipitate any metal. Be careful, the solution with peroxide will vigorously boil and release sulfur dioxide!

 

[OldManSam]

Oooof... Peroxide is a no-go. Okay ... so which of the following options do you think might work :

1) Add lots and lots of HCl (I'm only allowed 30% conc. in the house) and toss in zinc powder ... or

2) Evaporate it until everything precipitates, then cook what's left in my electromelt graphite furnace, then start back over from square one?

 

[Golddigger76]

We have a few questions that need to be answered in order for you to get some help getting your gold back.

What was the material you started with ? -- I know you said 22 grams of 8.5k but was it jewelry or what ?

How many milliliters of acid do you have 3 ?

How much acid and how much sodium nitrate did you use ?

Can you check the ph of your solution.

Was there anything that did not dissolve.

This honestly sounds like excess nitric but we can figure out if that is the case or not when you give us the details about the steps you took to get the original metals to dissolve.

Your gold is still there and worse case you may need to cement it out with copper

 

[OldManSam]

We have a few questions that need to be answered in order for you to get some help getting your gold back.

What was the material you started with ? -- I know you said 22 grams of 8.5k but was it jewelry or what ?

How many milliliters of acid do you have 3 ?

How much acid and how much sodium nitrate did you use ?

Can you check the ph of your solution.

Was there anything that did not dissolve.

This honestly sounds like excess nitric but we can figure out if that is the case or not when you give us the details about the steps you took to get the original metals to dissolve.

Your gold is still there and worse case you may need to cement it out with copper

I keep detailed logs ...

--------

The dissolution :

I started with a 20.53g pocket watch case, 8.5k gold. Technically not solid 8.5 ... this is a special type of double stock with a 14k shell and an 8k core. Not a standard GF watch. All non-gold parts had been stripped, including springs, movement, glass, etc.

I put it into my beaker and added a stir bar along with 300ml of 15% HCl, and 30g of NaNO3 at 6:15pm. Heat at medium.

At 7:23pm I added 300ml of HCl because there wasn't enough liquid in the beaker and the stir bar was splashing liquid.

I wasn't getting much reaction so I added another 10g of NaNO3 and 200ml more HCl. Then I turned the heat to high. Finally the reaction started cranking.

A little before 11pm the reaction had died again but there was significant metal remaining, so I added another 10g of NaNO3 and 250ml of HCl and let it run for several more hours. Afterward I cut the heat and went to bed.

In the morning there was still a bit of metal so I decanted what I had and set the remaining couple of grams aside.

--------

I put a pinch of prilled urea in to see if there was any fizz and there wasn't so I assumed that the lack of fizz coupled with metal remaining meant that there was not excess nitric.

Here's where the strangeness happens.

I put in SMB and saw a reaction. Gold started dropping out of solution. A couple hours later I decanted and kept the gold mud off to the side ... but there was not nearly as much as I expected - three grams, tops. I did the stannous test onto a small strip of filter paper and got an immediate black reaction in the decanted liquid. To me this means there's more gold in solution, so I hit it with more SMB - but this time I got nothing else to drop. The solution was a DARK blood red. This puzzled me because a) I got some gold to drop, and b) if there was still excess nitric it shouldn't have let me drop the other. I thought I was fully denoxxed but maybe not, so I tossed in some more prilled urea. Still no reaction, so I put in a pinch of sulfamic. Plenty of fizz from that, even cold, so I cranked up the heat and once it got nice and warm I started adding sulfamic. It fizzed plenty, and kept fizzing. I was getting frustrated at this point so I dumped a couple tablespoons of sulfamic in and let it dissolve as much as it could. Eventually as much dissolved as could be. The solution was nice and hot so it was super saturated.

At this point I turned off the heat and added just enough water to give the excess sulfamic somewhere to go. Once it was dissolved I let the solution cool. It was a beautiful golden color. I added a couple ice cubes to keep it from going all exothermy on me and tried more SMB. Big frothy foam, but no gold dropped.

That's where we are right now. How bad did I f- this up? I'm not used to working with poormans AR, and I'm only barely used to doing it the right way. Next time I'm going to bubble SMB gas through the liquid instead.

 

[goldshark]

Did you use city tap water, or distilled water?

 

[OldManSam]

Did you use city tap water, or distilled water?

All I use is distilled water, except the ice at the very very end.

 

[Yggdrasil]

Here's the situation ... I am not allowed (by the wife) to work with Nitric at home, so I am stuck using Sodium Nitrate to make poormans. I used this to dissolve about 22 grams of 8.5k gold in my fume hood, as one does, and had no problems doing so. Afterwards I discovered I had used too much NaNO3 and so I needed to denox. My solution was hot so I added sulfamic crystals and set my stir bar spinning.

After the sulfamic had dissolved I added a little more for good measure and eventually saturated the solution 😅 ... oops. At this point I needed to filter it to get the lead and excess sulfamic out anyway, so I did so. Afterwards I added some tap water ice to cool it down for precipitation...

Stannous test turned nice and black ... soooooo ... added SMB. Crazy foam but no precipitation. Thinking I was crazy I added more SMB but same result. I let it sit for several hours ... but nothing. Not even a dusting. Bear in mind I am expecting almost 9 grams of 24k, so to see nothing at all is unnerving.

Can anybody look at my process and let me know what I did wrong? Too much sulfamic? The tap water ice? For the life of me I don't think there is excess nitric in solution. Fresh stannous solution, too ... Is it possible I have pt group metals that I am confusing in the stannous test??? 😭

First get your Chemicals and refining out of your house NOW.
These are toxic and corrosive substances that will seep through everything and every where in its vicinity.
The nails will start rusting in the walls and so.
Find yourself a place outside to do it.

You have started out a bit on the wrong end.
First and foremost your Gold do not lend it self well for direct refining.
We usually do a inquartering first to bring the karat to 6 at which point you go the Nitric route.
Since you can not use Nitric that is pretty much it, for refining karat Gold we are dependent on Nitric. (Almost true)

What you have done is to dissolve some of the Gold on the surface until the Silver Chloride blocked access to the Gold.
I assume there is plenty of that Gold undissolved?

Your option seem to be to mechanically stir the items so the Silver Chloride is rubbed off during dissolving.
Or maybe there it is a possibility with smelting, not my area of expertise.

 

[Yggdrasil]

All I use is distilled water, except the ice at the very very end.

And lastly, your Gold do not drop because there is an excess of (Oxidizer)Nitric.
Urea is not recommended as a denoxing agent.

The best is to not add to much Nitric(Nitrates here), next best is to use Sulfamic acid, hot at appr 80 C
Sometimes we use the phrase: Urea belongs in the garden.
The reason is that Urea do not decompose neither Nitrates nor NOx, which Sulfamic acid do.
Next Urea lifts the pH which can cause problems if you use much.
And another benefit is that Sulfamic acid converts Nitric to Sulfuric acid and that will drop any lead in solution.

 

[OldManSam]

And lastly, your Gold do not drop because there is an excess of (Oxidizer)Nitric.
Urea is not recommended as a denoxing agent.

The best is to not add to much Nitric(Nitrates here), next best is to use Sulfamic acid, hot at appr 80 C
Sometimes we use the phrase: Urea belongs in the garden.
The reason is that Urea do not decompose neither Nitrates nor NOx, which Sulfamic acid do.
Next Urea lifts the pH which can cause problems if you use much.
And another benefit is that Sulfamic acid converts Nitric to Sulfuric acid and that will drop any lead in solution.

1) I have a fume hood.

2) I only use a tiny couple of prills of urea when denoxxing. My solution was cold and it is hard enough getting sulfamic to dissolve in hot water, but urea will react no matter what. I only use a few prills just to tell me if I need to use sulfamic or not.

I didn't have any problem dissolving all the gold. Inquartation was not required in this case. The problem is getting the rest of the gold to drop in a denoxxed solution.

 

[Yggdrasil]

1) I have a fume hood.

2) I only use a tiny couple of prills of urea when denoxxing. My solution was cold and it is hard enough getting sulfamic to dissolve in hot water, but urea will react no matter what. I only use a few prills just to tell me if I need to use sulfamic or not.

I didn't have any problem dissolving all the gold. Inquartation was not required in this case. The problem is getting the rest of the gold to drop in a denoxxed solution.

There are only two scenarios that will not let the Gold drop.
1 Too much Nitric/Nitrates meaning not deNOxed (Urea works by converting Nitric to Urea Nitrate)
2 Not acidic enough for the SMB to evolve SO₂

Since you have not told us how much HCl and Nitrate you used it is hard to say if enough Urea has been used.
Anyway Urea is still not recommended.

It is very strange that all dissolved in this setting anything less than 22 karat will be hampered by too much silver for the AR.
And anything higher than 6 karat will be hampered by too much Gold for the Nitric.
Are you sure it was a real Gold alloy?

You have a Fume hood which is great, and since it is in the house I expect it is running 24/7 too keep the fumes from chemicals and waste out of the house?

Seriously man, get the chemicals and processing out of your house or garage.

 

[Ultrax]

Can anybody look at my process and let me know what I did wrong? Too much sulfamic? The tap water ice? For the life of me I don't think there is excess nitric in solution. Fresh stannous solution, too ... Is it possible I have pt group metals that I am confusing in the stannous test??? 😭

Take a few milliliters of the solution for calcination. Dry the precipitate, and try to dissolve it with hydrochloric acid. If a brown residue remains insoluble after HCl, then you have accidentally obtained a SO-complex of gold and you will have to evaporate and calcinate the solution since chemical methods will not precipitate gold from it (except for 65% peroxide). It's easy to check in 15 minutes.

If you have added a lot of sulfamic acid and it does not fizz, then there cannot be an excess of nitric acid. But if there is a lot of SMB and you almost boiling the solution, free sulfur can form, which will react with SMB and form thiosulfate, which will instantly dissolve the dispersed gold, binding it into a complex.

 

[Yggdrasil]

1) I have a fume hood.

2) I only use a tiny couple of prills of urea when denoxxing. My solution was cold and it is hard enough getting sulfamic to dissolve in hot water, but urea will react no matter what. I only use a few prills just to tell me if I need to use sulfamic or not.

I didn't have any problem dissolving all the gold. Inquartation was not required in this case. The problem is getting the rest of the gold to drop in a denoxxed solution.

I have re read from the beginning.
The Magnetic stirrer might be the reason you manage to dissolve the Gold.
What did you do with the Silver Chloride?
Much of your Gold may be trapped inside the Silver Chloride.

 

[kurtak]

Did you use city tap water, or distilled water?

you only need to use distilled water when dissolving silver

when dissolving gold tap water works perfectly fine as you are working with chlorides any way (HCl) to dissolve the gold

Kurt

 

[OldManSam]

There are only two scenarios that will not let the Gold drop.
1 Too much Nitric/Nitrates meaning not deNOxed (Urea works by converting Nitric to Urea Nitrate)
2 Not acidic enough for the SMB to evolve SO₂

Since you have not told us how much HCl and Nitrate you used it is hard to say if enough Urea has been used.
Anyway Urea is still not recommended.

It is very strange that all dissolved in this setting anything less than 22 karat will be hampered by too much silver for the AR.
And anything higher than 6 karat will be hampered by too much Gold for the Nitric.
Are you sure it was a real Gold alloy?

You have a Fume hood which is great, and since it is in the house I expect it is running 24/7 too keep the fumes from chemicals and waste out of the house?

Seriously man, get the chemicals and processing out of your house or garage.

I'm operating out of a detached garage waaaay out in the desert south of Tucson. I'm a metalworker and silversmith by trade, but I have a chemistry background - I'm not just some rando. Nothing comes anywhere near the house.

The reason I am not allowed to bring in nitric is that just last year, at the literal exit off the interstate to where we live, a tractor trailer full of nitric tipped over on the interstate and did some major damage. It absolutely terrified the missus. The news media was warning folks to stay inside, and it was a massively bad environmental situation.

https://www.kold.com/video/2023/02/...rstate-10-near-kolb-road-leaking-nitric-acid/
You could see the NOx cloud from our front yard. 🤯

After that she made me promise to never bring it around.

As for your silver chloride question... I never had any form at all during the whole process.

 

[kurtak]

Apparently, your only option now is to evaporate the solution to dryness and calcinate the precipitate at 600oC-800oC. Then re-dissolve.

Although that is any option it most certainly is not the only option - & in fact if you have no experience with calcination you are taking a fair chance on having your gold go up in smoke (at least some of it)

Or use peroxide 65%,

65% peroxide is not available to the general public (the back yard hobby refiner) to get it - it needs to come from an actual "hazardous chemical" supplier that will sell to you & there will be hazmat shipping fees involved - if you can find a supplier willing to sell/ship to a general public client

At this point his best option is to cement it out with copper which will give him back his gold

Cementing with copper should give him back ALL his gold and it should come down as at least 98 % (with some copper contamination) & if done right should come down at (plus/minus) 99.5 %

In fact - because he has a stir hot plate he can use copper powder to cement the gold & get it to come down at 999 + --- there are a few tricks to doing that but if you know what you are doing it can be done

Kurt

 

[OldManSam]

Although that is any option it most certainly is not the only option - & in fact if you have no experience with calcination you are taking a fair chance on having your gold go up in smoke (at least some of it)

65% peroxide is not available to the general public (the back yard hobby refiner) to get it - it needs to come from an actual "hazardous chemical" supplier that will sell to you & there will be hazmat shipping fees involved - if you can find a supplier willing to sell/ship to a general public client

At this point his best option is to cement it out with copper which will give him back his gold

Cementing with copper should give him back ALL his gold and it should come down as at least 98 % (with some copper contamination) & if done right should come down at (plus/minus) 99.5 %

In fact - because he has a stir hot plate he can use copper powder to cement the gold & get it to come down at 999 + --- there are a few tricks to doing that but if you know what you are doing it can be done

Kurt

At this point I was leaning towards this ... Should some stripped Romex wire work? I'm not too concerned about losing a little gold at this point 😅 I just want this batch to be over and done so I can figure out why it was such a bear.

 

[Ultrax]

The 30% peroxide for swimming pools is very easy to evaporate to the desired concentration of 65-70% under a vacuum at 30-40C with some losses of 10-15%.

If there is H[AuCL4] in the solution, cementation will help.
For copper strip in solution, the minimum is a week with stirring.

If there is a thio-complex of gold there, you can cement it until you turn blue,
and nothing will happen.

But if I understand correctly, the author of the topic has already had enough time to check all the advice and find out the truth

 

[Yggdrasil]

I'm operating out of a detached garage waaaay out in the desert south of Tucson. I'm a metalworker and silversmith by trade, but I have a chemistry background - I'm not just some rando. Nothing comes anywhere near the house.

The reason I am not allowed to bring in nitric is that just last year, at the literal exit off the interstate to where we live, a tractor trailer full of nitric tipped over on the interstate and did some major damage. It absolutely terrified the missus. The news media was warning folks to stay inside, and it was a massively bad environmental situation.

https://www.kold.com/video/2023/02/...rstate-10-near-kolb-road-leaking-nitric-acid/
You could see the NOx cloud from our front yard. 🤯

After that she made me promise to never bring it around.

As for your silver chloride question... I never had any form at all during the whole process.

That you did not get any
Silver Chloride baffles me, that means the whole alloy was made without Silver,
nothing I have heard about before.

Regarding cementing it is best to use solid copper slabs or thick plates.

 

[kurtak]

At this point I was leaning towards this ... Should some chopped up Romex wire work? I'm not too concerned about losing a little gold at this point 😅 I just want this batch to be over and done so I can figure out why it was such a bear.

per the bold print - NO - that will result in heavy copper contamination of your recovered gold

Read this thread - it will give you all the info you need

https://goldrefiningforum.com/threads/fuzz-button-interconnects-need-some-advice.22203/#p232030
About two thirds or three quarters down on the first page you will see a picture of two beakers with copper in them - you want to use ether "heavy copper" copper - or - VERY fine copper "powder when cementing with copper

In your case - I would go to the hardware store & get some large bare copper wire the kind electricians use for grounding wire to ground the electric service panel coming into your house - # 6 or # 8 bare copper

Twist it into a coil like in the beaker on the right of the pic in the above thread link

Kurt