How can I speed up the gold separation

[leHAI]

I have 800 grams of material as shown in the picture. I used a mixture of 65% HNO3 and water at a 1:1 ratio, but it's been over three days, and the gold still hasn't fully separated. With my other materials, it only takes a few hours. How can I speed it up?

 

[Yggdrasil]

I have 800 grams of material as shown in the picture. I used a mixture of 65% HNO3 and water at a 1:1 ratio, but it's been over three days, and the gold still hasn't fully separated. With my other materials, it only takes a few hours. How can I speed it up?

What is the material?

 

[leHAI]

What is the material?

Gold and Niken

 

[Yggdrasil]

Gold and Niken

So Gold on Nickel?
Do you use heat?

 

[leHAI]

So Gold on Nickel?
Do you use heat?

Yes, that right. I used heat but not affect much

 

[anachronism]

The picture clearly shows the gold coming off. Have you tried heating it to 50 degrees C?

 

[leHAI]

The picture clearly shows the gold coming off. Have you tried heating it to 50 degrees C?

Yes, the gold is peeling off, but the process is too slow. It’s been over three days already, and I notice it’s slower compared to other materials. I’ve already boiled it.

 

[anachronism]

Yes, the gold is peeling off, but the process is too slow. It’s been over three days already, and I notice it’s slower compared to other materials. I’ve already boiled it.

I hear you. Have you kept it hot for a few hours or boiled it and let it cool?

 

[leHAI]

I hear you. Have you kept it hot for a few hours or boiled it and let it cool?

I just boiled and let it cool, so i think i should try to keep it hot in a few hours

 

[anachronism]

I just boiled and let it cool, so i think i should try to keep it hot in a few hours

Yeah, do that. For every 10 degrees C you heat it the reaction speed doubles. So if you heat by 40 degrees above room temperature the reaction will do 16 hours work in one hour.

This scales exponentially. A 50 degree raise will speed it by 32 times. 60 degree by 64 times, 70 by 128 times and so on.

 

[kurtak]

If this is gold plating on SS (Stainless Steel) & you don't have cyanide to strip (dissolve) the gold from the SS then you could try the "reverse" AR method to strip the gold from the SS

https://goldrefiningforum.com/threads/gold-gold-and-more-gold.22916/#post-240491

https://goldrefiningforum.com/threa...ss-for-watch-bands-_reversear_.20589/#p215472

Edit to add; - read what 4metals posted in this second link

Kurt

 

[Thomas M Joseph]

When concentration of nitric acid is above 30% (5.7 molar) passivation of the nickel surface occurs by the formation of nickel oxide as at this concentration nitric acid becomes a strong oxidizer. To prevent passivation use concentration less than 30%.

 

[Thomas M Joseph]

While heating can initially speed the reaction, prolonged and high temperatures can enhance the formation of the passivation layer and slow or even stop the reaction.

 

[4metals]

Unfortunately a lot of refiners feel if a little nitric works, a lot of nitric works faster. Typically this is not true. Even in parting Silver, the first acid should be 2 parts water to 1 part nitric. It simply works better!

 

[anarxi]

I have 800 grams of material as shown in the picture. I used a mixture of 65% HNO3 and water at a 1:1 ratio, but it's been over three days, and the gold still hasn't fully separated. With my other materials, it only takes a few hours. How can I speed it up?

add sulfuric acid with a density of 1.3.
the ratio should be:
1/1/2
water/nitric acid/sulfuric acid.
have some extra space in the glass, the reaction is quite violent.
like aqua regia.

 

[anarxi]

Unfortunately a lot of refiners feel if a little nitric works, a lot of nitric works faster. Typically this is not true. Even in parting Silver, the first acid should be 2 parts water to 1 part nitric. It simply works better!

In the USSR, a book was published
"Pure Substances" by Yu. Koryakin, first edition 1941.
It contains an article about silver and there sterling silver is dissolved with 16.5% nitric acid.

 

[4metals]

It contains an article about silver and there sterling silver is dissolved with 16.5% nitric acid.

It still takes the same amount of
Nitric to dissolve a gram of Silver so a weaker solution will require more volume of a dilute nitric acid.