# Precipitation Methods.



## Noxx (Feb 26, 2007)

When you made Gold Chloride with the Aqua Regia technique, you can either precipitate the gold in your solution with Copper, Zinc or Sodium Metabisulfide. Only use SM if you neutralised the acid with Urea. If it's not the case use copper or zinc.
Just put a little more precipitant than the amount of gold you expect.
If you expect 10g. of gold to come out, put 12g. of precipitant to be sure you won't left any gold in the solution.


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## Noxx (Feb 28, 2007)

Thanks for the info !


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## Anonymous (Mar 1, 2007)

Otherwise known as sulphite crystals, sodium metabisulphite is used in winemaking to sterilize equipment. I get mine at our local beer and wine "Hobby Brew" for 6 bucks per kg. Works like a charm to drop gold after you've killed the nitric with urea or by boiling down. You should test the solution after with gold detection fluid. Make your own with Hcl (muriatic acid at your hardware store) and tin. I use old pewter items which are about 65% tin.


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## shadybear (Mar 1, 2007)

Did you say you can drop from Aqua regis with zinc without using urea?


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## Noxx (Mar 1, 2007)

No ! You must first neutralise the acid with urea and then precipitate with what ever method you like.


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## Harold_V (Mar 2, 2007)

Noxx said:


> When you made Gold Chloride with the Aqua Regia technique, you can either precipitate the gold in your solution with Copper, Zinc .



That's not very good advice. Once you get your gold into solution, it's more than desirable to use a precipitant that's selective-----one that won't drag down other elements. Metals will---especially zinc. Any copper that follows the gold through the process will be precipitated along with the gold, so you haven't really improved it by much, if at all. 

Have you read about the use of ferrous sulfate? Sulfur dioxide? Both of them are very selective in that they precipitate only gold, and they're easy to use. The one disadvantage is that you must evaporate any excess nitric, otherwise the process isn't very effective, and a little of the gold tends to go back into solution when you wash it after precipitation. 

Harold


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## PRECIOUS METALS (Mar 2, 2007)

hey noxx how do you evaporate nitric or if your using aqua regia and how much gold goes back in the solution. do you fine ferrous sulfate? Sulfur dioxide. better than sodioum meta ,with your ver, the gold that goes back in the solution can it be retrived agian


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## Noxx (Mar 2, 2007)

With Aqua Regia, you do not evaporate nitric acid... you just neutralise it with urea. I don't know for the amount of gold dissolved... and I know nothing about ferrous sulfate and Sulfur dioxide pecipitation methods sorry. If there is still gold left in solution, yes you can always precipitate it again (If you haven't added anough precipitant)


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## lazersteve (Mar 2, 2007)

Anyone heard of BDG ?

It's a neat liquid that has a strong attraction to gold chloride! Better even still it is not miscible with water! When Butyl Diglyme is mixed with any aqueous based gold solution and shaken, it will separate out the gold with great effieciency and selectivity! The gold can then be precipitated out of the BDG with oxalic acid, hydrazine sulfate, and several other substances. The really amazing part is that the gold comes out as beautiful gold flakes of very high purity (99+). I've include a snapshot of a very small batch I have going now. 
The stuff is so cool, it is considered a green environment chemical and you can even reuse it indefinitely (with some evaporation losses)! As usual I have more info for those of you who are intereseted.











Steve


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## Noxx (Mar 2, 2007)

Cool stuff again ! Never heard about it. Where can you purchace this liquid ? Or make it yourself ?


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## lazersteve (Mar 2, 2007)

Ferro sent me four quarts for FREE !!!!

I sent them an email on their web site explaining what I was doing and inquiring about samples of the substance. I never got a reply back from them until one day about two weeks later a parcel from Ferro showed up out of the blue on my door step with TWO 2 Quart Bottles in it!!! I was shocked...BUT HAPPY.

FERRO RULES!!!

Steve


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## Noxx (Mar 2, 2007)

Strange but funny lol.


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## jmelson (Mar 3, 2007)

lazersteve said:


> Anyone heard of BDG ?
> 
> It's a neat liquid that has a strong attraction to gold chloride! Better even still it is not miscible with water! When Butyle Diglyme is mixed with any aqueous based gold solution and shaken, it will separate out the gold with great effieciency and selectivity! The gold can then be precipitated out of the BDG with oxalic acid, hydrazine sulfate, and several other substances. The really amazing part is that the gold comes out as beautiful gold flakes of very high purity (99+). I've include a snapshot of a very small batch I have going now.
> The stuff is so cool, it is considered a green environment chemical and you can even reuse it indefinitely (with some evaporation losses)! As usual I have more info for those of you who are intereseted.
> Steve


I'd definitely avoid the hydrazine sulfate, as hydrazine is an insidious poison. But, oxalic acid sounds pretty benign. I'd sure like to try this out myself! I sure don't want to get 4 L of the BDG delivered to me, however. I wonder if it will work with the cyanide stuff I'm using?

Thanks,


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## lazersteve (Mar 3, 2007)

Yes.


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## shadybear (Mar 4, 2007)

SO How do we get some of this BDG. Whats the address or web site.


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## lazersteve (Mar 4, 2007)

Shadybear,

Here is where I got mine.

http://www.ferro.com/Our+Products/Fine+Chemicals/Products+and+Markets/Gold+Recovery/

When you get yours let me know and I'll give you some help with the process if you need it.

Thank you for your interest in this intriguing technology.

Steve


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## shadybear (Mar 4, 2007)

Thanks for the info.
I have heard of this before about a year ago
a site called Goldmineworld.net had it for sale 
under the name gold stripper but they stopped selling it
sounds like it may work good let us know more


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## sandhog (Mar 6, 2007)

Steve,

Have you used it to dissolve gold from fingers? I was thinking about picking up a Gal. from Ferro (63.00 Gal.).


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## lazersteve (Mar 6, 2007)

Socorban,

The BDG doesn't dissolve metallic gold, only gold in combined form like gold chloride. You must first get the gold into solution using AR, Acid-Peroxide, Chlorine Water, or any other chemical mix that will dissolve gold into solution. If you can filter the gold out of a liquid it is not in solution. If you test a solution with the stannous chloride test and it shows positive the BDG will extract the gold into the ethereal layer (upper layer).

Here's the link to the formula for stannous chloride:

http://goldrefining.110mb.com/phpBB2/viewtopic.php?p=104&highlight=#104

Steve


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## sandhog (Mar 6, 2007)

Thanks for clearing that up Steve.


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## sandhog (Mar 6, 2007)

Steve,

Do you add this directly to your acid peroxide or do you precipitate first, use BDG? Also what do you use to precipitate Acid/Peroxide? SO2?

-Bill


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## lazersteve (Mar 6, 2007)

Acid peroxide is a relatively slow acting etchant/solvent for gold. If the gold is finely divided and allowed to soak in the peroxide mixture the gold will dissolve. AR will dissolve it much faster. Once this step is complete the BDG can be used to extract the gold chloride into the upper layer. It then gets washed (shaken in a sepratory funnel) twice with dilute acid to push any base metals to the lower aqueous layer. The top layer containing the gold is drained out of the funnel into a pyrex vessel and aqueous oxalic acid is added to the vessel along with a magnetic stirring rod. This vessel is magnetically stirred over night or longer (depending on temperature) to precipitate the pure flakes of beautiful gold. 

I have a detailed document on the process I will freely share with anyone who obtains there own BDG and want to try this method. The BDG works on any form of dissolved gold no matter how the gold was transferred into solution (AR, Acid/Peroxide, etc.)

Steve


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## sandhog (Mar 6, 2007)

Thanks Steve,

I was reading about this acid peroxide process and one of the articles I read it seems the peroxide was added about 1hr. after the gold bearing material has soaked. Is this the procedure you use or do you just mix and soak?

-Bill


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## sandhog (Mar 6, 2007)

Steve,

Also, I will be purchasing BDG tomorrow.

-Bill


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## Noxx (Mar 6, 2007)

What did you told them to get a free sample ? 8)


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## sandhog (Mar 6, 2007)

I e-mailed Ferro and they e-mailed me a price list. I'm going to call them tomorrow to see if I can get a sample.

-Bill


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## sandhog (Mar 6, 2007)

By the way Noxx.... Great job on the forum

-Bill


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## Noxx (Mar 6, 2007)

Thanks sandhog. I'm happy you like the forum. What are their price list ? Could you send it to me by PM ?
I told them I am the owner of goldrefiningforum.com and my community and I would like to have more informations about the product  I also ask them if I could get a free sample. I hope they will agree to send one here in Canada !


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## lazersteve (Mar 6, 2007)

I'm not sure why or how I lucked up on the freebie guys, but the four bottles even have barcodes and labels on them with my name, address, and the date they were made in the lab! Just like a prescription or something.

Do you want me to post pix of the bottles?

I must make a correction:

*Correction: They shipped me two 2 quart bottles still nearly four liters just in two bottles not four. I just realized that the nitric acid came in the 1 litlers not the BDG, sorry about that. I whited out my address info as well to protect my privacy.*

Steve


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## Noxx (Mar 6, 2007)

yep please


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## shadybear (Mar 7, 2007)

this sounds like dbg would work great with iodine.
would'nt you be able to leach into iodine remove 
the gold with dbg. And put the iodine right back to leaching again.


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## lazersteve (Mar 7, 2007)

Shadybear,

I haven't used it with Iodine so I can't answer this one accurately. I'll do some checking on the MSDS for BDG and see if it mentions reaction with iodine. 

Steve


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## Paige (Apr 28, 2007)

1. Will nitric acid evaporate faster than HCL?

2. Could you just set the aqua regia outside and start the evap of nitric before adding urea?

3. Is it possible for aqua regia to evaporate completely and if so, what happens to the gold in it? Did it go up into the atmosphere?

4. With a combination of boiling off the nitric and adding urea, how do you test to see if the nitric is all gone?

5. I have seen discussion about boiling down AR to a syruppy state and then adding more HCL. I have boiled it down, but it never got to that point. Broke some glassware trying and lost gold!

6. I had gold assayed by atomic absorbtion method and got to .996. I neglected to run my gold chloride thru ammonia to get any last bit of AG; I guess that is where I went wrong. Are you safe in geting to .999 by going thru AR twice, with good distilled water rinsing in between, along with washing with ammonia twice? Can anyone think of another step to get there?

Thank you.

Paige


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## AgAuPtRh (Apr 28, 2007)

Paige -- go to the Help Needed Threads and look for the " getting gold shining" Read that and you'll have an awesome thread on your question.

AgAuPtRh


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## Harold_V (Apr 29, 2007)

Paige said:


> 1. Will nitric acid evaporate faster than HCL?



No. Nitric is difficult to expel, and comes off after water and HCL have pretty well be exhausted. 



> 2. Could you just set the aqua regia outside and start the evap of nitric before adding urea?



Considering your object here is to recover gold of high quality, setting anything outside to evaporate, unless it was to get well filtered before evaporation, would be less than wise. You have no idea what will end up in your container. Besides, the temperature needed to adequately evaporate the nitric would not be available. It's not easy to evaporate, which is why people have chosen to use urea. 



> 3. Is it possible for aqua regia to evaporate completely and if so, what happens to the gold in it? Did it go up into the atmosphere?



You can carry the process too far. As the chloride solution becomes more and more concentrated, the color shifts. If you started with relatively pure gold, it will go from a honey color towards red, then darken until it's pretty much black. If there's no more nitric in solution, and you add hydrochloric, eventually you start seeing miniscule particles of gold that precipitate on their own. If you continue heating long enough, you'd probably reduce the entire lot to metallic gold, although I can't speak from experience. I always did my best to avoid getting past the dark red stage. 

You risk losing your gold if you evaporate too quickly. The temperature of the solution must be held on the cool side, just enough to evaporate the solution, certainly not high enough to boil. That drives off the gold very quickly. You can often see color in the vapor when you go too fast. I did it a few times, although not intentionally. It pays to have a filtered fume hood for such instances. 

I never used urea----I always evaporated, but I also added a button of sacrificial gold of known weight to the solution to help eliminate the excess nitric by consuming it. It makes evaporating a lot easier. 



> 4. With a combination of boiling off the nitric and adding urea, how do you test to see if the nitric is all gone?



Way beyond my knowledge. I'll let someone else take this one. 



> 5. I have seen discussion about boiling down AR to a syruppy state and then adding more HCL. I have boiled it down, but it never got to that point. Broke some glassware trying and lost gold!



You have to be a little wise when you're doing this operation. For one, the temperature of the chloride will be well above the boiling point of water and the solution will still be tranquil. You have to be careful that you add fluids before the lot hits the super heated stage. Using an added button of gold solves a lot of problems. Also-----if you choose to use glassware, make certain it's borosilicate glass or better. Otherwise you should expect breakage, and you will get it! Even with borosilicate glass, you have to be careful. It tolerates heat quite well, but doesn't tolerate thermal shock. If you use a hotplate, make certain you have an insulating layer between your container and the heat. I used asbestos pads, but they may be impossible to get these days. 



> 6. I had gold assayed by atomic absorbtion method and got to .996. I neglected to run my gold chloride thru ammonia to get any last bit of AG; I guess that is where I went wrong. Are you safe in geting to .999 by going thru AR twice, with good distilled water rinsing in between, along with washing with ammonia twice? Can anyone think of another step to get there?



I'm not sure I followed you properly here-----but if you said you failed to run your gold chloride through ammonia-----that's probably a good thing. AS far as I know, you should never introduce your gold chloride to ammonia. I stand to be corrected if I'm wrong. 

What you'd do is wash the *precipitated gold *in ammonium hydroxide between HCL washes-----that will remove traces of silver chloride. 

I suggest you follow the link recommended. I talked about how I ran my gold, and the quality was very good. You need to brush up on your washing, from all indications. I make specific recommendations in the thread referenced. 

Harold


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## Paige (Apr 29, 2007)

Many, many thanks, Harold.


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## Irons (Sep 17, 2007)

Harold said:

"I'm not sure I followed you properly here-----but if you said you failed to run your gold chloride through ammonia-----that's probably a good thing. AS far as I know, you should never introduce your gold chloride to ammonia. I stand to be corrected if I'm wrong.

What you'd do is wash the precipitated gold in ammonium hydroxide between HCL washes-----that will remove traces of silver chloride. "

The 'Ammonia' that you can get at the grocery store is actually dilute Ammonium Hydroxide.

If you bubble Ammonia through water, that's what you get.

Ammonia is a gas NH3

Ammonium Hydroxide is Ammonia dissolved in water NH4OH or NH3-HOH


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## Batman75 (Aug 8, 2018)

lazersteve said:


> Acid peroxide is a relatively slow acting etchant/solvent for gold. If the gold is finely divided and allowed to soak in the peroxide mixture the gold will dissolve. AR will dissolve it much faster. Once this step is complete the BDG can be used to extract the gold chloride into the upper layer. It then gets washed (shaken in a sepratory funnel) twice with dilute acid to push any base metals to the lower aqueous layer. The top layer containing the gold is drained out of the funnel into a pyrex vessel and aqueous oxalic acid is added to the vessel along with a magnetic stirring rod. This vessel is magnetically stirred over night or longer (depending on temperature) to precipitate the pure flakes of beautiful gold.
> 
> I have a detailed document on the process I will freely share with anyone who obtains there own BDG and want to try this method. The BDG works on any form of dissolved gold no matter how the gold was transferred into solution (AR, Acid/Peroxide, etc.)
> 
> Steve


 Steve I have recently obtained 110 gallons of diethylene glycol dibutyl ether and would like to know the process


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