Method for Ultra High Purity Gold

[Geo]

I remember when I first joined the forum, four 9's was the rage and there was a lot of talk about it. Then the high purity discussion died down after someone showed pure gold crystals grown in a plasma furnace (can't remember the exact post) and that was the holy grail of refining at the time. It takes high tolerance equipment to purify gold to the chemically pure state of six 9's. I would be too embarrassed to state that I can purify gold to acceptable bullion grade and I have practiced quite a bit. I'm not being modest but just truthful. If I try my hardest, I'm sure I can get 99.5 but I'm not stretching it any farther. That's already stretching a little bitty thing a long way.

 

[solar_plasma]

Obviously it is just a question of expense. When four 9's can be obtained at first refining simply using diglyme, more than this seems not to be so hard - if expense is no object.

 

[Lou]

I should emphasize that this method produces gold sponge that serves as the feedstock for chemical vapor transport into the single crystal clusters that I posted about (that was me Geo). Gold of that purity is sold to other refiners as reference standard. Sometimes the product is better than existing standards.

 

[Anonymous]

Nickvc has made a good point on many occasions, and it does go some way to validate at least one of Mod's assertions.

That is, you only get paid for the gold content of a button. If it's 99% gold then you get still get 100% of the gold value by weight. There's an argument for refining to 99% or below purity if you have a steady out turn for your gold at those levels of purity.

The point where it becomes cost prohibitive to keep increasing purity is something that does need to be kept in clear perspective if you're selling your gold. Obviously if you're keeping it and making it pretty then it's a completely different story.

Jon

 

[4metals]

Years ago, before the jewelry manufacturers in the US started to leave, there was an excellent market for a small to medium sized refiner to make high purity metals. As that market has dwindled considerably, there is still industrial needs for high purity metals but nowhere the quantity or need there once was.

If you are selling to a refiner or even to a major, you will have your refined metals discounted when you sell. Whomever you sell to assumes they will have to re-refine it and it will likely be assayed and thrown in with the high grade feed. For gold that is likely >99% gold content.

For this reason I tell my clients who sell karat bars to refiners and only refine the material requiring stone removal that a single drop of the gold without getting carried away will give you the purity needed to sell at the best price. No sense putting time energy and chemicals into an unprofitable situation.

However to be well versed in the art of refining it pays to know how to make high grade gold and for that reason a thread like this is valuable to help you figure out steps you can easily do to increase your purity and keep costs down.

Who knows, maybe one of the national labs will call you and want .9999 gold and you'll have a market. If they want .999999 gold, call Lou!

 

[JohnBB]

I may have made an error..I wonder if anyone can help me..

I used Dibutyl Carbitol for the first time...I mixed together my completed Aqua Regia solution containing my gold and PGRMs.. the total 750 mls went completely into the (140F degrees) DBC solution and a color change took place after 24 hrs. I then filtered out any solids and remaining AR solution... then made up Oxalic Acid 1000g/1L and made 2 L, which I heated to 80 C. I added the DBC pregnant solution heated to 80C to the Oxalic and stirred for 24 hrs at 80C...I received no gold Chloride drop.

Prior to the Ox/DBC mixing I also washed the pregnant DBC solution with (337 ml 37% HCL with 2663 Mls DI water 4 times). The wash water was yellow and last wash was pretty clear.

1.) Can I still recover the gold from the DBC or the acid wash or the Oxalic acid layer(which is now yellow), and if so, where exactly is the gold now? I have saved all solutions separately.

2.) My DBC was from TCI chemical company of Japan.

PLUS..some posts mention Ammonia...?

I am not sure what to do next...Please send rescue service..;-)

Thank you,

john

 

[MarcoP]

Hi John, I can only help by finding out where your gold is. Prepare some Stannous Chloride and test your solution.

Marco

 

[Geo]

To my understanding, solvent extraction is a messy business. The two solutions, AR and DiButyl Carbitol (DBC) will not mix. Think in terms of oil and water. After the two has been mixed together to allow the DiButyl Carbitol to touch all of the AR solution, you should allow the two solutions to separate. The AR solution should be depleted of precious metals and can be removed with a separatory funnel. Of coarse it should be tested with stannous chloride to be sure. Now you have the DiButyl Carbitol to deal with.

If this did not happen, you did something wrong. If you did do all of this, you should have explained in your post exactly what you did and how you did it. Did you heat the pregnant solvent when adding the oxalic acid? Were you constantly stirring while you added the oxalic acid?

 

[Lou]

John,

DBC will load about 130-150 g/L of gold and do it in a few hours tops. You want to use good stirring (preferably overhead) and then allow the phases to settle.
You can then wash the extract like you've done with HCl to scrub out any iron or other crap.

You heat the oxalic solution to boiling with the DBC with good stirring and you get high purity gold. The washes should have not much of anything in it, perhaps Fe/Pd. You can recycle those to another digest.

Lou

 

[Research135]

I also had/have procedures for rhodium, palladium, platinum, rhenium, osmium, ruthenium, and iridium. I suppose they're not useful from the aspect of recovery, but they are highly useful as far as refining goes.
I think these procedures are enlightening just from the standpoint of it being the pinnacle of refining let alone from practical value it has for us as refiners in improving our technique.

As I find them, I will post them. Moderators willing, perhaps we can move them into another thread and sticky it for future reference.



Lou

That would be an interesting read, for sure.

 

[colt45gto]

wow, Thanks Lou but i think i need to be able to crawl before i can walk with this.

this isn't gold refining its chemistry at a super level. to me anyway.

i feel cleverer already!

 

[Tndavid]

Very interesting read on the ultra high purity gold. I would love to see some videos of the process. Or pictures from beginning to end product. That would be awesome. Thanks Lou and all the rest of you guys.

 

[RaAt2]

From karat gold.
1-Inquart with silver. Granulate and part in nitric acid. Decant. Boil residue in sulfuric acid. Decant.
2-Dissolve residue in HCl and sodium chlorate. Add a few drop of sulfuric acid. Let it stand. Decant and filter clear solution.
3-Add 5% zinc chloride `to clear solution. Add sodium hydroxide dropwise till PH is near 7. Let it stand. Decant clear solution.
4-Add HCl till pH is 4. Add Butyl Diglyme. Shake. Decant organic phase. Rinse organic phase with HCl twice.
5-Add hot sodium oxalate/ HCl mix at pH 4. Keep heat on.
6-Wash several times with pure HCl and distilled water.
7-Melt in zirconia crucible with oxyhydrogen torch. Product is 6N + .

 

[Tndavid]

From karat gold.
1-Inquart with silver. Granulate and part in nitric acid. Decant. Boil residue in sulfuric acid. Decant.
2-Dissolve residue in HCl and sodium chlorate. Add a few drop of sulfuric acid. Let it stand. Decant and filter clear solution.
3-Add 5% zinc chloride `to clear solution. Add sodium hydroxide dropwise till PH is near 7. Let it stand. Decant clear solution.
4-Add HCl till pH is 4. Add Butyl Diglyme. Shake. Decant organic phase. Rinse organic phase with HCl twice.
5-Add hot sodium oxalate/ HCl mix at pH 4. Keep heat on.
6-Wash several times with pure HCl and distilled water.
7-Melt in zirconia crucible with oxyhydrogen torch. Product is 6N + .

Pics???

 

[4metals]

He has been banned. Although very clever!

 

[Ravn]

Hi

In the Journal Hydrometallurgy there is an interesting paper on how to make gold with purity >99,9998 % (>5N) using a relative simple process.

Hydrometallurgy 95 (2009) 262-266
"Processing of high purity gold from scraps using diethylene glycol di-N-butyl ether
(dibutyl carbitol)" Byoung Hi Jung a, Yi Yong Park a, Jeon Woong An c, Seong Jun Kim c, Tam Tran b, Myong Jun Kim

 

[FrugalRefiner]

Dibutyl carbitol is also know as butyl diglyme, or BDG. You'll find many posts about the process if you search for BDG.

Dave

 

[Ravn]

Dibutyl carbitol is also know as butyl diglyme, or BDG. You'll find many posts about the process if you search for BDG.

I am well aware of the different names for Dibutyl Carbitol. I was only trying to inform about a new simple process for producing high purity gold :wink: