Gold from aqua regia

[avigp193]

I have completed all process and added SMB to precipitate gold .
Then also reaction took place and gold dust start precipitating in good quantity too as I have processed more than 1 kg mix ic chips.
But I put that solution for 5..6 hours and I went away for some work. And now when I am retuned to my place I am seeing that the solution is again yellow all precipitate gone into solution again. So wheta the problem here and what's the solution for this? Help needed.

 

[4metals]

What did you use to dissolve the gold? Did you test with stannous to determine all of the gold had dropped in the photo on the left? Did you test the solution on the right with stannous?

Any answers given without more details will only add to confusion.

 

[Martijn]

I have completed all process and added SMB to precipitate gold .
Then also reaction took place and gold dust start precipitating in good quantity too as I have processed more than 1 kg mix ic chips.
But I put that solution for 5..6 hours and I went away for some work. And now when I am retuned to my place I am seeing that the solution is again yellow all precipitate gone into solution again. So wheta the problem here and what's the solution for this? Help needed.

Probably your 'all process' contained excess oxidizer which is redissolving the gold.

Solution is add more gold to dissolve and use up the excess oxidizer.

To be honest, 'all process' is an awfull lot. You could have been done with just one or two. I prefer process 3.

 

[avigp193]

Probably your 'all process' contained excess oxidizer which is redissolving the gold.

Solution is add more gold to dissolve and use up the excess oxidizer.

To be honest, 'all process' is an awfull lot. You could have been done with just one or two. I prefer process 3.

What did you use to dissolve the gold? Did you test with stannous to determine all of the gold had dropped in the photo on the left? Did you test the solution on the right with stannous?

Any answers given without more details will only add to confusion.

Thanq so much guys gor giving me your precious time.
I am new to this profession.
But I figured out my mistake by myself and solved it.

The mistake was the acide was not nettalused completely datz y I think
Precipitated gold again got mixed in the aqua regia.


Solution that worked: I added sulfamic acide in few quantityto the solution then again added sodium meta bi sulfite then it worked like charm again the gold got precipitated.

 

[Sunnyket]

Hello,
Can we dissolve precipitated gold dust again in fresh aqua regia ?
(I mean precipitated gold dust without melting directly dissolving in AR)

 

[Yggdrasil]

Hello,
Can we dissolve precipitated gold dust again in fresh aqua regia ?
(I mean precipitated gold dust without melting directly dissolving in AR)

Yes but you do not need to use AR, better use HCl and strong Peroxide.
You will have no need for controlling and destroying Nitric that way.
And of course it makes no sense to melt it to a button for then dissolving it again.

 

[Sunnyket]

Yes but you do not need to use AR, better use HCl and strong Peroxide.
You will have no need for controlling and destroying Nitric that way.
And of course it makes no sense to melt it to a button for then dissolving it again.

Thanks for clearing the doubt, I asked this question because sometimes in the refining process mistakenly or accidentally other metals go along with gold and it is difficult to identify without melting and testing. As I'm thinking It is easy to dissolve in powder form.

 

[Sunnyket]

Yes but you do not need to use AR, better use HCl and strong Peroxide.
You will have no need for controlling and destroying Nitric that way.
And of course it makes no sense to melt it to a button for then dissolving it again.

In that case, I'll try the peroxide method. Thanks