# Aqua Regia and Dibutyl Ether



## wesza (Dec 14, 2012)

After Aqua Regia Process (Nitric Acid, Muriatic Acid, following instructions with Diethylene Glycol Dibutyl Ether not having effect with particles floating to surface.


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## Geo (Dec 14, 2012)

i did a pretty good search on this stuff. is it suppose to be a reducing agent, because im seeing things like "strong oxidizer" and "solvent" aside from a pretty large context of warnings about the toxicity of Diethylene Glycol, i dont find anything that would suggest that it might precipitate anything. it is carbon based and will decompose into carbon dioxide.its used in alot of paint. maybe one of our chemist can help. 

is this something you've done before and are just having trouble this time or is this something you have never done and cant get it to work right?


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## jimdoc (Dec 14, 2012)

wesza said:


> After Aqua Riga Process (Nitric Acid, Muriatic Acid, following instructions with Diethylene Glycol Dibutyl Ether not having effect with particles floating to surface.



Where did you find these instructions you are following?

Jim


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## Geo (Dec 15, 2012)

ok, theres another member thats new talking about recovering gold using BDG,( butyl diglycol) and from what i can find,this is very similar. its a solvent,its ether,its an acetate.what does it do in the field as far as refining. is it an oxidizer or reducer?


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## Gratilla (Dec 15, 2012)

Here's a list of some of the aka's (in alphabetical order) for the SAME THING. The most common names with their TLA's are in red.

2-Butoxyethyl ether 
Bis(2-butoxyethyl)ether 
Butyl DiGlyme BDG
DiButyl Carbitol DBC
Dibutyl diglycol 
Dibutyl diethylene glycol 
Dibutyldiglycol
Diethylene glycol dibutyl ether 
Diethylene glycol di-n-butyl ether

It's an organic solvent for use in solvent extraction for gold chloride from acid leaches. Detailed instructions for its use can be found with a Search.


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## g_axelsson (Dec 15, 2012)

It was discussed a lot a couple of years ago. BDG is a good solvent for gold chloride. Basically you do it in three steps. (As I remember from the discussion, never tried it myself.)

1. Mix BDG with a dirty solution of gold chloride. Most of the gold chloride will dissolve into the BDG.
2. As BDG makes up a separate phase from the water it can easily be parted from the now almost barren dirty solution.
3. Pour the pregnant BDG solution onto a solution with a reducing agent, oxalic acid were the one of choise. In the interface between the two phases gold is reduced back to metallic and is falling to the bottom of the reducing solution. The barren BDG can now be reused in step 1 again.

As this is from memory only, anyone wanting to test this procedure has to do the proper research on how it actually is done.

I would like to test it myself but haven't been able to find anyone in my area that is selling BDG.
Thanks for the list, Gratilla, it makes it easier to find a seller. 

Btw, it's spelled aqua regia, not Riga, that's the capital of Latvia.

/Göran


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## bswartzwelder (Dec 15, 2012)

What are TLA's? It's perfectly ok to use acronyms. But there are many new members who are not familiar with all the acronyms in use, especially here. When I worked in the nuclear industry, any time you used an acronym, the first usage had the wording spelled out and then put the acronym in parenthesis. After that, everyone knew what you were referring to.


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## g_axelsson (Dec 15, 2012)

You are correct, it's a good thing to write any acronyms out at least once in your post, it also makes it easier for the search engines to catch it when you are searching for a post.
You can't find AR with the search engine, but if you include (aqua regia) once you can search for that.

Btw (by the way) I didn't spell it out in my post as the post before gave nine different names for the same chemical. ;-)

/Göran


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## Geo (Dec 15, 2012)

"two-letter acronym"


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## Gratilla (Dec 15, 2012)

bswartzwelder said:


> What are TLA's? It's perfectly ok to use acronyms. But there are many new members who are not familiar with all the acronyms in use, especially here. When I worked in the nuclear industry, any time you used an acronym, the first usage had the wording spelled out and then put the acronym in parenthesis. After that, everyone knew what you were referring to.



You're perfectly correct (and I've been known to say the same myself). To put the record straight:

AKA (Also Known As)
TLA (Three Letter Achronym)
BDG (as above) - Butyl Diglyme
DBC (as above) - DiButyl Carbitol

I guess an apology is in order. <mumble, mumble> :mrgreen:


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## NobleMetalWorks (Dec 15, 2012)

I have been using Hydroquinone with excellent results. It's pricy but it does a great job selectively precipitating Au from dirty solutions.

Scott


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## ericrm (Dec 15, 2012)

how does bdg and Hydroquinone react with an excess of nitric acid?


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## NobleMetalWorks (Dec 15, 2012)

I'm not sure about BDG but I think of precipitants in solutions of excess nitric acid like this.

No matter what precipitant you are using, once your Au precipitates out of solution as particles of Au, the free nitric (oxidizer)immediately reacts, along with the hydrochloric, to re-dissolve the gold particles back into solution. This is why you see the NOx gas evolve when you add the precipitant, because the Au is re-dissolving and converting to AuCl. So long as your solution is still Aqua Regia and not totally converted to AuCl, you will re-dissolve the precipitated gold not matter what precipitant you use.

Aqua Regia is only Aqua Regia so long as the solution has not been totally converted to AuCl, once all the Nitric Acid (oxidizer) has been used up, it then should be either AuCl or a complex of whatever other metals + AuCl.

I wouldn't attempt to precipitate Au from a AR solution (free nitric acid) because Hydroquinone is pricy. If you are doing things correctly, you shouldn't have any excess nitric acid anyway.

Scott


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## Gratilla (Dec 16, 2012)

ericrm, I think maybe you're confusing "apples and oranges", ie two different methods of selectively recovering gold from a lixiviant (AR in this case), specifically

a) selective precipitation (ie with the Hydroquinone), and 
b) solvent extraction (ie with the BDG)

With (a) the precipitant is added to the lixiviant to reduce gold chloride to gold metal. Because the precipitant is reducing, any oxidising agent (nitric acid in the case of AR) interferes with this and needs to be removed. There are a number of ways of doing this (Search on the forum for details).

With (b) BDG is added to the lixiviant to selectively extract the gold chloride after which the precipitant (usually oxalic acid or SMB - Sodium MetaBisulphite) is added; the oxidising agent is irrelevant for this as it is no longer in the picture. One of the mods did post detailed instructions for extracting with BDG, although I couldn't find it on a quick Search attempt.


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## ericrm (Dec 16, 2012)

Gratilla said:


> With (b) BDG is added to the lixiviant to selectively extract the gold chloride after which the precipitant (usually oxalic acid or SMB - Sodium MetaBisulphite) is added; the oxidising agent is irrelevant for this as it is no longer in the picture. One of the mods did post detailed instructions for extracting with BDG, although I couldn't find it on a quick Search attempt.



so if i understand right you add bdg to a gold chloride bearing solution ,mix them together ,bdg will extract gold chloride from solution ,you than collect your bdg back to precipitate gold later...
but i dont know how bdg will react , ive been looking for a way to avoid denoxing with realy dirty solution , could bdg do it (remove gold from a not denoxed solution?

edit : i think i understand what you mean , since basicaly bdg only absorbe gold chloride , when i will remove bdg ,nitric acid will be left behind so when i will drop the gold there simply wont be any nitric involve in the dropping processus to create problem ...


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## ericrm (Dec 16, 2012)

Gratilla said:


> One of the mods did post detailed instructions for extracting with BDG, although I couldn't find it on a quick Search attempt.


does someone know whos that mods was?


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## butcher (Dec 16, 2012)

Use the search engine on laser Steves web site.

Here is what I got when I typed in BDG, you can get more results with different key words.

http://www.google.com/search?hl=en&as_q=BDG+&num=1000&ft=i&as_sitesearch=goldrefiningforum.com&as_qdr=all&as_occt=any



see this link in palladiums post (download/file.php?id=2354)
http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=49&t=5505


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## ericrm (Dec 16, 2012)

search for bdg in grf :

Board index

Information

No suitable matches were found.

bdg search in google :

Gold Refining Forum.com • View topic - BDG question
goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=49...
11 posts - 6 authors - 12 Aug 2009
I read noxx's tutorial about refining with BDG but something seem unclear. BDG is supposed to be highly incompatible with nitric acid, and in ...

thank you butcher


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## Geo (Dec 16, 2012)

why have i not been told about this sooner? honestly, this seems to be very doable and something i will be working towards. no more triple refining dirty drops or working on one batch for days because of all the contamination.i would never had known about this if it hadnt seemed so incredible i had to start asking questions about it. 

http://goldrefiningforum.com/phpBB3/download/file.php?id=2354


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## butcher (Dec 16, 2012)

Geo how do you get that link to move (or copy and paste) and stay blue where others can click on it and it work?
I tried it to copy and paste it would not work.


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## Geo (Dec 16, 2012)

butcher said:


> Geo how do you get that link to move (or copy and paste) and stay blue where others can click on it and it work?
> I tried it to copy and paste it would not work.



right click the link and choose "copy link address" and paste where you want it.


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## Gratilla (Dec 16, 2012)

ericrm said:


> so if i understand right you add bdg to a gold chloride bearing solution ,mix them together ,bdg will extract gold chloride from solution ,you than collect your bdg back to precipitate gold later...
> but i dont know how bdg will react , ive been looking for a way to avoid denoxing with realy dirty solution , could bdg do it (remove gold from a not denoxed solution?
> 
> edit : i think i understand what you mean , since basicaly bdg only absorbe gold chloride , when i will remove bdg ,nitric acid will be left behind so when i will drop the gold there simply wont be any nitric involve in the dropping processus to create problem ...



You've pretty much got it. 8) Now if someone can find those detailed instructions ... Maybe they're in the GoldRefiningForum books (online @www.scribd.com).

Solvent Extraction (SX or SeX :mrgreen should be in every refiner's "bag of tricks" IMO. It's almost a silver bullet in that it can zero in on just AuCl3 (or other compounds/PGMs, depending on choice of organic solvent) pretty much irrespective of the other gunk in the aqueous mix. The moderator's instructions should let you "do it by the numbers" without needing to understand the theory. However if you want to tweak for optimum results you really need to understand details of Distribution Coefficients (solubility in organic phase divided by aqueous phase) and how these change with the Normalcy/Molarity/pH of the aqueous phase. (For strong acids like HCl 1N = 1M. ie 1 Molar, which you can calculate from atomic weights.)

I've attached an example below. Just look at Fe (a pretty common pollutant in Au solutions). This varies between just over one part per thousand (in your organic phase) at O.5 N HCl and close to 50% at 2.5 N HCl. Obviously you'd want your HCl concentration to be 0.5N or less to not have the Fe largely carried over to your organic solvent (ie BDG) during extraction.

BTW, if you want more details, look up the patent (US 5,942,024), shown on the attachment below.


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## Geo (Dec 17, 2012)

im having a hard time finding a source for BDG. can anyone give me a product name or a good source please. there are so many different names for it, i can find a few with part of the total acronyms but never a whole. a close match is Diethylene Glycol. its a gel fuel.


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## Gratilla (Dec 17, 2012)

Try here:

http://www.tcichemicals.com/eshop/en/us/commodity/B0828/
http://www.sciencelab.com

BTW, there are over a dozen synonyms for BDG/DBC (dunno why) and also lots of different chemicals with close/similar names.

To be on the safe side quote the (unique) CAS Code: 112-73-2.


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## Geo (Dec 17, 2012)

thank you very much Gratilla.


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## ericrm (Dec 27, 2012)

can someone tell me if you absolutely have to shake by hand dbg and gold bearing solution, or could you simply use a stirrer and let it stir it for a few hours and get the same result?


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## scrappile (Dec 27, 2012)

Metallurgy/dibutyl carbitol




DiButyl Carbitol is a very useful extractant for gold, especially from mixed acid solutions. It goes by several names, including...

Diethylene glycol dibutyl ether
Bis(2-butoxyethyl)ether
Butyl diglyme
Dibutyl carbitol
Dibutyldiglycol = Diethyleneglycol-di-n-butyl ether
Dibutyl diglycol
2-Butoxyethyl ether
Diethylene glycol di-n-butyl ether

It can be purchased in smaller quantities from www.sciencelab.com.

Are you aware that the solvent can be re-used? It really never wears out, just wash it good with water and hydrochloric acid and you can use it many times over. It helps to be careful with your separation, to avoid losing any. I have made seven nines gold many times using DBC, precipitated with a 10% solution of oxalic acid over a 48 hour period. Good luck... 


http://en.allexperts.com/q/Metallurgy-2280/dibutyl-carbitol.htm

can reuse too, .. :shock:


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## Gratilla (Dec 27, 2012)

ericrm said:


> can someone tell me if you absolutely have to shake by hand dbg and gold bearing solution, or could you simply use a stirrer and let it stir it for a few hours and get the same result?


The only things you absolutely have to do (in a democracy) is:
a) Pay taxes and
b) Die (eventually)

Think about what effect you're trying to accomplish. You're trying to mass transfer the AuCl3 from the aqueous to the organic phase. In order to do this in a reasonable amount of time you need to:
a) Agitate (to distribute the AUCl3 evenly in the two phases), and
b) Maximise the surface area between the two (to minimise the time required).

With a typical stirrer you're only stirring the bottom (ie aqueous) phase, with minimal effect on the mutual surface area.

I found that my first attempts at shaking were too vigorous and I created an emulsion that took days to separate. Now I just rock my separatory funnel vigorously from side to side. <Some music with an appropriate beat helps.>


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## Geo (Jan 26, 2015)

Since oxygen helps the volatile absorb the gold chloride, why not us a glass tube to bubble air through the solution. It would serve two purposes, add oxygen and agitate the two solutions together.


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