Precipitation of Gold using SMB

Hi,

I am new to this & I've tried to precipitated the gold using SMB, Unfortunately yield is very low.
I had 7g of pure gold scraps, before melting with Aqua Regia. How ever after gold precipitation using SMB, weight of gold dust is less than 1 g. If any one can explain, What had went wrong?..

Thanks

Asanka

1.No other person visited? 2. Why transform "pure" gold to amorphous powder

Since you haven't described the process in detail, we have to resolve to guessing.
My guess would bee too much nitric in the Aqua Regia for the amount of gold.
If that is true you have to get rid of the excess nitric.

There are many ways to do that.
I'll guess Sulfamic acid would be fastest, slow evaporation to a syrup are the method described by C.M Hoke.
It is wise to read C.M Hokes book before you continue experimenting.

You'll find links in the forum, amongs other places under FrugalRefiners posts

Hi.. Thank you for the reply.

I added 10 ml Nitric acid to 30 ml HCL for the AR formation. However I've litlle bit large amount of Aqua Regia to the gold metal scraps.. Is it be the case?.. Also solution came up with very little gold dust and with green/yellow (luminous) color solution.

Regards,

Asanka

Hi.
I'm not so well versed in the numbers to say if that is excessive or not.
The generally accepted procedure here is add a bit surplus HCl (cover what you want to dissolve), then add nitric in small increments until all is dissolved or reaction stops.
Then add a bit more HCl to see if the reaction starts up again.
This way one keep the nitric levels to what is absolutely neccesary.
Some even add a bit more gold to make sure all nitric has been spent.

Just a question:
Was this carat scrap?
If so, the silver may have formed silver chlorides that inhibits dissolution of the gold.

Did you denox the solution?
http://goldrefiningwiki.com/mediawiki/index.php/Denoxing

Make some stannous chloride so you can test the remaining solution for dissolved gold.
http://goldrefiningwiki.com/mediawiki/index.php/Stannous_chloride

How can you be sure you started with 7g of pure gold?

Göran

Sorry Gøran!
Forgot those points as they seemed too obvious :roll: :wink:
It is good to see the pros pitching in, to keep us on the straight and narrow....

Hi.. Thank You All for the reply.

I've added more SMB to precipitate the remaining gold in the solution. But still not precipitated. Color of the remaining solution is Greenish / Yellow (Luminous color)..

Regards,

Asanka

Maybe it is best if you describe your process in detail.
Where did the material come from, was it pure, carat, plated?
How did the process go?
Anything left from the AR?
As detailed as you can.

Then do as Gøran said, test the solution with stannous chloride, follow the link he gave.
If it still has gold in it, it will show clearly.
If there are still gold in solution denoxx it and try again.

The greenish color of the solution does indicate that the material you dissolved at least had some copper in it.
Please if possible post pictures.
A picture will tell a story by itself