Citric acid method gone wrong maybe?

[Torx]

Hi everyone!
So being new to gold refining I thought I would try the citric acid way of removing foils off of some ram sticks. I used 300ml of distilled water and mixed in 25g of citric acid, 20g of salt and 25ml of 3% hydrogen peroxide. Once it was all mixed I added a few ram sticks and set it aside.

After about 5 hrs it looks like the some of the gold fingers have turned a copper colour? is this normal. I would have thought that the foils would slowly drop off since they wouldn't dissolve in the mixture? Is the copper cementing itself back onto the gold?
The liquid is also a bit cloudy but doesn't have a blue or green tinge from the copper either?

cheers
Torx

 

[Martijn]

Could you share where got this method from? A link or piece of text would help a lot.
I suspect a cheap substitute for AP. With possible nasty or unnecessary complicating side effects, why we usually advise against.
So wrong process maybe?

 

[Torx]

Could you share where got this method from? A link or piece of text would help a lot.
I suspect a cheap substitute for AP. With possible nasty or unnecessary complicating side effects, why we usually advise against.
So wrong process maybe?

I had watched a few online videos with the citric acid method from YouTube. This one and this one and a few others. I thought that since its a nice mild way to remove the gold from the sticks id try that first. I used 3% hydrogen peroxide that you can buy from the shop, maybe its not strong enough?
Could there be some tin or lead in the solution making it do what its doing? I only tried it on a small amount of ram sticks so if I cant save it then its ok.

 

[Safiye]

for the green foils removing (plastics) have you ever try sodium hydroxide solution?

Hi everyone!
So being new to gold refining I thought I would try the citric acid way of removing foils off of some ram sticks. I used 300ml of distilled water and mixed in 25g of citric acid, 20g of salt and 25ml of 3% hydrogen peroxide. Once it was all mixed I added a few ram sticks and set it aside.

After about 5 hrs it looks like the some of the gold fingers have turned a copper colour? is this normal. I would have thought that the foils would slowly drop off since they wouldn't dissolve in the mixture? Is the copper cementing itself back onto the gold?
The liquid is also a bit cloudy but doesn't have a blue or green tinge from the copper either?

cheers
Torx

 

[rickbb]

"NaCl is a neutral ionic compound that completely dissociates into Na+ and Cl- ions when dissolved in a polar solvent such as water. NaCl + Citric Acid <==> Citric Acid + NaCl. This mixture can be used as a saline buffer for biochemical reactions."​

Adding salt to citric acid does not make a viable acid to dissolve copper from under the gold plating. It makes citrate, which as you have discovered does nothing to your fingers.

Save yourself quite a bit of time and trouble and just get some muriatic acid, (HCL), and go from there doing it the proper way.

Search this forum for the AP process, it's well discussed and documented here.

 

[Torx]

"NaCl is a neutral ionic compound that completely dissociates into Na+ and Cl- ions when dissolved in a polar solvent such as water. NaCl + Citric Acid <==> Citric Acid + NaCl. This mixture can be used as a saline buffer for biochemical reactions."​

Adding salt to citric acid does not make a viable acid to dissolve copper from under the gold plating. It makes citrate, which as you have discovered does nothing to your fingers.

Save yourself quite a bit of time and trouble and just get some muriatic acid, (HCL), and go from there doing it the proper way.

Search this forum for the AP process, it's well discussed and documented here.

Thanks rickbb

I'm going to filter off and rinse the fingers and then chuck them in some AP

 

[Martijn]

Try to avoid using H2O2 or use very little as a first oxidizer to get the copper chloride leach going.

 

[Martijn]

for the green foils removing (plastics) have you ever try sodium hydroxide solution?

NaOH is used to remove solder mask from PCB's before the AP process. It does not release the gold foils from the copper layer.

 

[Lino1406]

Citric acid + NaCl will give weak HCl, hence you have weak AP in this method. Heating is essential and lot of time

 

[Martijn]

In one of the video's he still has to use HCl to dissolve insoluble copper chloride to get the foils out. So if you need it anyway, no need to replace it with citric acid and salt.