# Dissolving gold in AR premixing vs incremetal - VIDEO



## kadriver (Nov 18, 2017)

This video kicked my behind.

I was getting ready to dissolve and precipitate yesterday morning to get the gold ingot on the truck to the refiner by yesterday afternoon.

But then I said to myself, "self, this would make a good teaching video".

I couldn't remember how premixed aqua regia behaved because its been so long since I used it.

During precipitation the difference is startling! The video is long, because it took so long to drop the gold from the premixed AR side of the experiment.

https://youtu.be/PNMkR-opWvI

kadriver


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## chuckgambale (Nov 18, 2017)

Fantastic! What a great way to visually show the importance of incremental nitric additions. Your videos have been a wealth of information for myself and others, so thank you for all that you have contributed to all of our collective knowledge. That was a heck of a lot of SMB in the pre mix beaker. The only other thing that could have been done differently was to maybe show how to denox using sulfamic acid instead of copious amounts of SMB. By the way I am so looking forward to seeing you process that stock pot. I really can't wait.


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## anachronism (Nov 18, 2017)

Also do bear in mind the following:

The premixed version is absolutely fine in some circumstances i.e. When you have more than enough raw material to easily use up the Nitric over many additions of said raw material. For example- you have 10Kg of ceramic processors, or 10Kg of fingers. So it does have its place and it would be remiss to give a blanket opinion that it is no good. Remember that in those jobs you're adding product in smaller batches into the premixed AR and not adding the premixed AR to the whole pile of product.

I would also agree that Sulphamic would have been the best option for destroying the Nitric although the SMB will of course do the job over time. 

I would finally wholeheartedly agree that premixing AR for small jobs is not a sensible process. Hope that helps.

Jon


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## Lou (Nov 18, 2017)

Premix definitely doesn't keep.


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## g_axelsson (Nov 18, 2017)

Lou said:


> Premix definitely doesn't keep.


And the reason it doesn't was very clear in the video, it turned a nice golden hue of dissolved NOx gases in the beaker even before added to the gold. The aqua regia solution breaks down into gas over time.

It was interesting to see the big difference in color between the gold chloride in hydrochloric acid and in aqua regia with a lot of nitric left. I didn't know it was that big difference between the two methods as I've never used premixed AR.

I've tried to fight the nitric acid with SMB once and that time was when I decided to always denox before precipitate gold, it takes a whole lot more than you would believe. This video shows that clearly.

Thanks again for sharing.

Göran


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