Refining Gold to 999.9% but frosty rough edge finish?

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platinum01786

Member
Joined
Apr 7, 2018
Messages
10
Hi,

i have been refining gold using an aqua regia refining plant but for some reason i am unable to get the shiny mirror finish on the gold. instead i get rough edges and a frosty surface only ( see pic) a fraction of it will be shiny so heres what i have done to try and fix the problem

- percipitate using metabisulphate and stop at 500 minivolts to ensure no percipitation of platinum group metals
- Ensure input material has no lead and silver content is below 5%
- refined material twice
- used 32% HCL and 60% nitric 3:1 ratio
- used 36% hcl and 6% nitric 3:1 ratio ( this made things worse)
- wash percipitated gold powder with HOT HCL
- Wash powder with Boiling water
- wash with distilled water
-melting the powder into distilled water for granulation
- granulating in distilled water and denatured alcohol
- melting powder using vacuum casting
-using electrolysis machine to achieve .99999
unfortunately none of these worked
can anyone suggests how i can achieve mirror finish surface. the issue is not with the melting part or purity (as i have seen 99.5% bullion look shinier) but somewhere in the refining process. see attached image has some craking in it also
 
Getting shining gold: https://goldrefiningforum.com/phpBB3/viewtopic.php?f=49&t=325
Maybe this helps..
You can also introduce impurities when melting. Use new or cleaned material.
Martijn.
 
its such a precise art i mean the slightest imperfection anywhere just screws the whole thing up
ill share pictures on my next batch in a few days.
have you guys figured a way we can get 99.99% everytime with aqua regia?. because electrolysis is ridiculously long
ive been told to only percipitate 3/4 of the gold this will ensure no other metals get percipitated along with it e.g. platinum group metals.
 
You could dissolve twice and precipitate with copperas the second time.
Proper washing procedure before going to the second AR step would improve it even more.
 
Yes refining twice with AR and optionally using different methods to precipitate the gold.
Different precipitants are more or less selective to different impurities and can help to get rid of difficult to separate traces of metals.

Copperas is iron sulphate crystals or green vitriol.
I've seen sreetips use it once, and that took a lot more to drop all the gold compared with SMB imo. I have never used it myself.

Refining twice with SMB would also give a cleaner result than once with SMB.
Once you have fine gold powder, its easy to wash with different acids. Maybe a nitric bath at the end of the washing procedure could help.

Martijn.
 
Martijn said:
Once you have fine gold powder, its easy to wash with different acids. Maybe a nitric bath at the end of the washing procedure could help.
Click to expand...

Be careful about following an HCl bath with HNO3 or vice versa. Any remaining traces of the first acid can create a tiny amount of AR when the second acid is added.

Dave
 
Hello
My way to get shiny, high purity button is :
- first dissolve in AR and precipitate with SMB
- second dissolve in AR then precipitate with NaNo2
- third dissolve with AR and finally precipitate with Oxalic acid.
This way You'll get very high purity and shiny gold when You melt in a fresh clean dish and take care about clear tip of Your torch aswell.
 
hi im gonna try your suggestion naporex and let you know how i get on
any idea on how much oxalic acid i used to percepitate per gram of gold ?
and is it a powder or a liquid
 
and btw i normally melt in a 10kw italian melting furnace with a medium frequency
converter (whatever that is) but its supposed to assist in making it melt effectively
 
I think I have the solution to your problem
Here check out this video you will get how to make your gold shiny https://youtu.be/E7IH5mR1VJ8
 
effectively this video has 2 things which i haven't tried

- he adds na2co3
- he ads borax (during melting)

im not sure how these 2 will affect it but ill give it a go anyway.

its not difficult to get shine on shot grain as i use a vacuum induction granulator which effectively melts in a closed chamber environment and its partly just an oxidization problem but if you want to get the lustrous shine like how large companies do thats where we get stuck as the tips on the forum is edging us so close but still not quite there. purity i manage to achieve using the tips on the forum is .99992 - .99998 which is more than
acceptable (double AR and HCL + Amonia washes) but that shine that heavenly shine is still in the pipeline.
 

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