Aqua Regia method with 12-13% Ag _inquart_

[giahylxag]

The green is from the Copper.
Did you roast the bracelet first?
Separate the clasps and such?

Just update more pictures. No I did not roast it first. Maybe there are alot of dirt there. Also the bracelet is more like a bangle so there is not many parts to seperate

 

[4metals]

I see you have decided to start with the aqua regia approach as the result of your heated discussion with your chemist friend.

Apparently the 13% Silver is too high to effect a complete dissolution and you do have encapsulated gold that has not dissolved. That gold is now coated with a dark green yellowish coating which is what the residue of gold alloy coated with Silver Chloride looks like when it is not completely rinsed.

The dark colored acid is from the copper as pointed out.

You will not, in the end when it is dried and melted, recover all of the gold. A percentage is tied up in chlorides and since you did not have the benefit of tumbling that percentage will be higher than it would be if you tumbled.
,
For this experiment to convince you and your aqua regia inclined friend you should now take a sample of similar size, inquart it, and part it in nitric. You will then, with proper parting have >99% gold after rinsing which, when refined in aqua regia, will produce a nice red - orange acid after the reaction and will yield a very high purity gold.

Try the inquarting, you will come back completely converted to an inquart man. Then your chemist friend owes you a beer!

 

[giahylxag]

I see you have decided to start with the aqua regia approach as the result of your heated discussion with your chemist friend.

Apparently the 13% Silver is too high to effect a complete dissolution and you do have encapsulated gold that has not dissolved. That gold is now coated with a dark green yellowish coating which is what the residue of gold alloy coated with Silver Chloride looks like when it is not completely rinsed.

The dark colored acid is from the copper as pointed out.

You will not, in the end when it is dried and melted, recover all of the gold. A percentage is tied up in chlorides and since you did not have the benefit of tumbling that percentage will be higher than it would be if you tumbled.
,
For this experiment to convince you and your aqua regia inclined friend you should now take a sample of similar size, inquart it, and part it in nitric. You will then, with proper parting have >99% gold after rinsing which, when refined in aqua regia, will produce a nice red - orange acid after the reaction and will yield a very high purity gold.

Try the inquarting, you will come back completely converted to an inquart man. Then your chemist friend owes you a beer!

Luckily the sample size is very small (7.5g) so gold loss is not considerable.
Next question is why there is a very thin layer of gold on the surface when I drop SMB in? Is it supposed to be sand-like and brown and drop down to the bottom?

 

[Yggdrasil]

Luckily the sample size is very small (7.5g) so gold loss is not considerable.
Next question is why there is a very thin layer of gold on the surface when I drop SMB in? Is it supposed to be sand-like and brown and drop down to the bottom?

There are many kinds of reactions going on and some of the Gold might attach itself to fatty substances and other dirty stuff and float.

 

[4metals]

Did you filter the solution before you processed it further? You also did not mention any method you used to deal with the free nitric acid. If metabisulfite is used and there is free nitric acid the reaction of precipitating the Gold and the redissolving of the Gold often takes place floating on the surface in dirty or improperly filtered solutions.

Done right the gold dropped is heavy and sinks easily.

 

[giahylxag]

Did you filter the solution before you processed it further? You also did not mention any method you used to deal with the free nitric acid. If metabisulfite is used and there is free nitric acid the reaction of precipitating the Gold and the redissolving of the Gold often takes place floating on the surface in dirty or improperly filtered solutions.

Done right the gold dropped is heavy and sinks easily.

Yes I did filter it, I filtered out all the AgCl (maybe some gold in it, too).
About the free nitric, I just boiled it for some time, dropped a little ure and saw no reaction.
For this particular test, things work fine at the moment, the gold dropped, the solution is very clear, the thin gold layer is gone. I will update pictures tomorrow
But I use at least double the amount of SMB (in weight) compared to my gold.

 

[giahylxag]

There are many kinds of reactions going on and some of the Gold might attach itself to fatty substances and other dirty stuff and float.

I am very careful with my tools and glasswares. But I didn't roast the bangle first, maybe that was the problem, it was dirty

 

[Yggdrasil]

Yes I did filter it, I filtered out all the AgCl (maybe some gold in it, too).
About the free nitric, I just boiled it for some time, dropped a little ure and saw no reaction.
For this particular test, things work fine at the moment, the gold dropped, the solution is very clear, the thin gold layer is gone. I will update pictures tomorrow
But I use at least double the amount of SMB (in weight) compared to my gold.

Boiling will do nothing to the Nitric.
And Urea is not complete and can create dangerous compounds.
The two best methods is not use too much Nitric or use Sulfamic acid.

 

[4metals]

I have processed a lot of chemical stone removal where the jewelry is digested as it is received. You cannot heat it to red heat to burn off any oils because it will ruin the stones. As a result the reaction occasionally had a golden film on the acid from the oils holding small particles. Usually the prolonged hot aqua regia reaction was enough to take care of the problem, but they were larger lots. Small refining lots are the most difficult to do properly because you are looking for so little gold and the solutions are dilute.

 

[giahylxag]

Update
I calculated there must be at least 4 gram of pure gold but i recieved just 2 gram. Look like I made a big mistake. I burned the filter paper by a torch and the ash just flying around. Or a lot of gold is trapped in the AgCl

 

[Yggdrasil]

Update
I calculated there must be at least 4 gram of pure gold but i recieved just 2 gram. Look like I made a big mistake. I burned the filter paper by a torch and the ash just flying around. Or a lot of gold is trapped in the AgCl

Both is most likely true.
If you want to have good accountability.
You will need to have good process control and good lab procedures.

 

[nickvc]

With chemical / wet refining your loses will be much higher by percentage in small lots as opposed to larger lots if you process properly and carefully and stone set material is not easy to get a decent return due to mixed alloys / karats that do not fully dissolve .
Most processing loses are recoverable some time later when time and quantity make recovery worthwhile.

 

[giahylxag]

Both is most likely true.
If you want to have good accountability.
You will need to have good process control and good lab procedures.

How to properly burn the filter paper and get the gold. I don't think the torch is okay, many vids I have seen on youtube they just straight burn it by a torch (streetips guy for example).

 

[Yggdrasil]

How to properly burn the filter paper and get the gold. I don't think the torch is okay, many vids I have seen on youtube they just straight burn it by a torch (streetips guy for example).

That will be filters with Gold metal powder in it, not "Dirty" filters with chlorides and such.
If you are properly ashing paper it should be heated to around 300-500 degrees C and combust by itself in open air.
If we are talking of Filters as Sreetips do in videos, they are cleaned Gold metal and can be heated and melted directly.
You need to keep focus on the details.

 

[giahylxag]

That will be filters with Gold metal powder in it, not "Dirty" filters with chlorides and such.
If you are properly ashing paper it should be heated to around 300-500 degrees C and combust by itself in open air.
If we are talking of Filters as Sreetips do in videos, they are cleaned Gold metal and can be heated and melted directly.
You need to keep focus on the details.

I did use the cleaned gold filter and I was talking about it. But the the filter paper created ash and shot itself around
I used Whatman filter

 

[Yggdrasil]

I did use the cleaned gold filter and I was talking about it. But the the filter paper created ash and shot itself around

If it is Gold metal there should not be losses by the ash.
But proper filter paper usually create very little ash.
Ignition it and let it burn, then start heating the powder until it melt.
Watch Sreetips/Kadriver until you understand.

 

[Shark]

Some filter papers produce less ash than others.

 

[Yggdrasil]

Some filter papers produce less ash than others.

It was an attempt to get some information from the user

 

[giahylxag]

I think
Because my lot is so small, most of the gold particles are stick on the filter paper's wall, then I burned it, gold comes along the ash.
There is a thread on this forum but i am not quite sure

 

[giahylxag]

I am building my fume scrubber based on this design, very simple using PVC pipes and a water tank.
https://goldrefiningforum.com/threads/new-fume-scrubber-design.22553/But I couldn't find numbers that tells me
1. NaOH concentration: after a few searchs on the internet, i found that 12% to 20% is recomended. Is that Ok?
2. How much NaOH liquid to effectively neutralize, let say 50oz of inquarted gold (using silver), I am using a 10L can, is this enough?