Gold precipitation in aqua regia does not work

damocles

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Apr 18, 2021
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Hello To all,

Thank you for the details Göran.
But on any doc I did read they always say AR need to be done 3:1.
So for example 75ml HCL 25ml Nitric

so in this example you say I need to use same quantity of HCL but less nitric acid ?

Ok for the neutralize I got it will try to use the right terms for the future :) denoxing and first of all undertand how to ;-)

I agree with you for youtube and ... I also agree to say that this is how I got the idea to scrap gold ;-).
So I started with a lot of wrong information reason why I came to this forum to read more and more post talking about the way to recover gold from AR.

Will read more on denoxing thank you ;-).

For the other chemicals I will stay on the SMB and Iron Sulfate II for now with a preference for the Iron sulfate that was for my opinion more easy to use.

I will read this Hoke everybody is talking about seem like it will be necessary if I want to better understand what I am doing.

Thank you again for your answer Göran you did really clarify things.

Thank you for your answer Nickvc

I will give a try with a copper bar I have a lot of them on heatsinks but will this make the whole gold that left in the bucket will cement or just a bit to show me there is still gold in it ?


Thank you to all the community for your kindness and for having answered me so quickly and well, really a great forum, interesting and dynamic

Oliver
 

g_axelsson

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damocles said:
Hello To all,

Thank you for the details Göran.
But on any doc I did read they always say AR need to be done 3:1.
So for example 75ml HCL 25ml Nitric

so in this example you say I need to use same quantity of HCL but less nitric acid ?

Yes, hydrochloric and nitric acid is consumed in the rate of 3:1 when dissolving gold and a rule of thumb is that it takes about 1 ml nitric to dissolve 1 gram of gold. (Actually with reflux you could go as low as 0.6-0.7 ml/g)
As you know an excess of nitric acid needs to be removed before precipitating the gold. But an excess of HCl doesn't hurt and is even necessary when using SMB. Nitric is also difficult to get and expensive for most people, so therefore the recommendation is to add enough HCl to complete the reaction or cover the objects and then add nitric as needed. It is cheaper, creates less waste and makes it easier to get back the gold in the end. The drawback is that it might take some more work and a bit more time.

There is a guy on youtube right now, I think his channel is called Trinity refining or something like that and he could add a liter of nitric to dissolve 10 grams of gold. He creates huge amounts of waste and consumes a lot of chemicals and my only comment to his videos is "Why!!!". It's so wasteful and according to my calculations he is also losing gold.

You should also study "stock pot" and "cementing", it will reveal the answer on your question about copper. :wink:

Göran
 
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