# Hydrogen Hydride or Sodium Metabisulphite for gold recovery



## jdgold (Sep 23, 2014)

Hi 

I am doing the gold recovery from sweep dust that we collected from our gold workshop using aqua regia. I wanted to know which would be better option to use for gold recovery after it has dissolved into aqua regia and turned to auric chloride. Options are hydrogen hydride or Sodium Metabisulphite. Also I have read and heard people using urea after using the recovery chemical. What is the benefit of using urea?

In short what are the benefits of hydrogen hydride vs sodium metabisuphite?

Benefits of using urea?

Regards

JD


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## Geo (Sep 23, 2014)

The good news is, you found the forum. I will give you a couple of answers but we insist that you study the forum and download a copy of C.M. Hoke's book "Refining Precious Metal Waste" and start studying that as well. When I answer you, it will just lead to more questions on your part unless you study and get a good grasp of what your doing. 

If you already dissolved the metal with AR, there's no need for the H2O2. Hydrogen peroxide is used to put gold into solution, not precipitate it out of solution. Sodium metabisulfite will precipitate gold out of solution. Forget the urea. People use it to remove the excess free nitric acid in solution. It works but the risk (no matter how small) is still too much when there's something that works just as good if not better, sulfamic acid. 

Now, see what I mean? Study the process you want to do and that way you can ask questions that actually help and you will understand the answer.


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## butcher (Sep 23, 2014)

jdgold,

Geo is giving you great advice.

I have a question, what are you calling Hydrogen Hydride, I can understand metal hydrides, but am confused by the term Hydrogen Hydride.


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## g_axelsson (Sep 23, 2014)

Hydrogen peroxide can precipitate gold, but it's more of a curiosity since there are better methods and all is discussed on the forum.

http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=37&t=17252

Göran


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## goldsilverpro (Sep 23, 2014)

Maybe he meant hydrazine hydrate.


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## Geo (Sep 23, 2014)

Reading the MSDS on hydrazine is like reading a horror novel. It's toxic and poisonous to every living thing. People that deal with it daily wears a full hazmat suit. I hope that's not what he was talking about.


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## FrugalRefiner (Sep 23, 2014)

Geo said:


> Reading the MSDS on hydrazine is like reading a horror novel. It's toxic and poisonous to every living thing. People that deal with it daily wears a full hazmat suit. I hope that's not what he was talking about.


Not to diminish the dangers of hydrazine, but have you ever seriously looked at the MSDS for Clorox bleach? 

*hydrazine Exposure Controls/Personal Protection*

*Engineering Controls:*
Provide exhaust ventilation or other engineering controls to keep the airborne concentrations of vapors below their respective
threshold limit value. Ensure that eyewash stations and safety showers are proximal to the work-station location.
*Personal Protection:*
Face shield. Full suit. Vapor respirator. Be sure to use an approved/certified respirator or equivalent. Gloves. Boots.
*Personal Protection in Case of a Large Spill:*
Splash goggles. Full suit. Vapor respirator. Boots. Gloves. A self contained breathing apparatus should be used to avoid
inhalation of the product. Suggested protective clothing might not be sufficient; consult a specialist BEFORE handling this
product.

*bleach Exposure Controls/Personal Protection*

*Engineering Controls:*
Provide exhaust ventilation or other engineering controls to keep the airborne concentrations of vapors below their respective
threshold limit value.
*Personal Protection:*
Face shield. Full suit. Vapor respirator. Be sure to use an approved/certified respirator or equivalent. Gloves. Boots.
*Personal Protection in Case of a Large Spill:*
Splash goggles. Full suit. Vapor respirator. Boots. Gloves. A self contained breathing apparatus should be used to avoid
inhalation of the product. Suggested protective clothing might not be sufficient; consult a specialist BEFORE handling this
product.

Be sure to put on your moon suit before you do the laundry next time.

Dave


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## solar_plasma (Sep 23, 2014)

Sometimes it is the amount, that makes something more dangerous. Some 1000l tanks chlorox in a container that is leaking and I would never get close to it without the level A suit. Hydrazine is very scaring, because of the five GHS pictograms, the 4-4-3 hazmat diamond and because it is cancerogen.


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## jdgold (Sep 24, 2014)

Hi Geo

Thanks for your advice. I was suggested to read the book when I had first posted in this forum. I have read the whole book as well as I have been doing a lot of research on net . I came across hydrazine hydride (My mistake, I checked and it was not hydrogen hydride) somewhere and wanted to know if that was better option. I came across many ways to recover gold from auric chloride and wanted to know which was the best. I want to know which is the best and cost effective gold recovery chemical? 

Also do you mean to say Sulphamic acid is better substitute to urea to dilute the nitric acid? Why do you say so?

Regards

JDgold


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## Geo (Sep 24, 2014)

When you add sulfamic acid to a warm solution containing excess nitric acid, the excess is converted to N2O (nitrous oxide) and sulfuric acid in solution. This will deplete the free nitric from solution. The nitrous oxide is impure and should not be consumed as it also contains NOx and a couple other nasty elements. Warm the solution to below a boil and add the sulfamic slowly in increments. It can be added in crystal or in solution. I put mine in solution as it seems to speed up the reaction time. The reaction it vigorous and a boil over is possible so only fill your container to only a quarter to a third of it's capacity. 

Urea is a precursor to some very explosive components.


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## heliman4141 (Sep 24, 2014)

Geo said:


> When you add sulfamic acid to a warm solution containing excess nitric acid, the excess is converted to N2O (nitrous oxide) and sulfuric acid in solution. This will deplete the free nitric from solution. The nitrous oxide is impure and should not be consumed as it also contains NOx and a couple other nasty elements. Warm the solution to below a boil and add the sulfamic slowly in increments. It can be added in crystal or in solution. I put mine in solution as it seems to speed up the reaction time. The reaction it vigorous and a boil over is possible so only fill your container to only a quarter to a third of it's capacity.
> 
> Urea is a precursor to some very explosive components.


 
Geo,
Do you mix your Sulfamic with plain distilled water to liquify the crystals as one would with say SMB? 
I picked up 3lbs. of Sulfamic crystals & was wondering if it was better to liquify it first with water.
Ive got a Hcl/cl batch in the works & a nitric/Hcl batch going & its for the nitric batch, when im ready to pre-filter prior to dropping.




Dave


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## Geo (Sep 25, 2014)

Some people like to use it in crystals (one crystal at a time) to gauge how much free nitric there is in solution, of course it takes a little finesse and experimentation to get that one right. Or you can add enough crystals to make the reaction move faster (be careful of boil overs). Like I said, I like to dissolve mine. Use distilled water and make sure the water gets saturated for good results. Also, I don't heat the water. It dissolves well enough at room temperature. The sulfamic acid will actually chill the water as it dissolves. I feel that heating may be detrimental to the properties of the sulfamic acid in some way, just my opinion. It dissolves about as fast as table salt in water. 

As an aside, this works well with depleting silver nitrate of free nitric acid before you start cementing the silver with copper.


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## heliman4141 (Sep 25, 2014)

Geo said:


> Some people like to use it in crystals (one crystal at a time) to gauge how much free nitric there is in solution, of course it takes a little finesse and experimentation to get that one right. Or you can add enough crystals to make the reaction move faster (be careful of boil overs). Like I said, I like to dissolve mine. Use distilled water and make sure the water gets saturated for good results. Also, I don't heat the water. It dissolves well enough at room temperature. The sulfamic acid will actually chill the water as it dissolves. I feel that heating may be detrimental to the properties of the sulfamic acid in some way, just my opinion. It dissolves about as fast as table salt in water.
> 
> As an aside, this works well with depleting silver nitrate of free nitric acid before you start cementing the silver with copper.





Thanks much for the information,
I had no idea you could use it that way & that it cooled things. Am looking forward to using it.

Dave


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## denalixtc (Dec 13, 2018)

Hi all,

I hope I am not thread jacking, but I was trying to find an answer to a question I had and this is where it led me.. If I am posting in the wrong location please let me know.

I have several refining/recovery projects in the works - all at different stages of the process, as I obtain materials at different times. To the point...

I think I made a mistake and took the wrong bottle and added urea and sodium meta bisulfate to solution to precipitate prior to dissolving the solution in hydrochloric acid and Nitric acid. 

Is there a way to reverse this process ie. "un-precipitating" and getting the urea and sodium metabusulfate out, so I can add the HCL and HNO3 in the proper order, or is this batch shot? 

I'm letting the solution sit over night to see what it looks like in the morning as I may have used the corrected bottle to precipitate, but just in case I'd like to get my ducks in a row to do whats necessary to reverse the processes I did - if possible. --its a small amount so I'm not too worried about it.

I did a stannous chloride test on the solution and the liquid on the paper remained colorless. odd.

Thank you for your help and advice in advanced.


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## butcher (Dec 13, 2018)

denalixtc,

I am having trouble understanding your question(or what you did to what) can you rephrase it?


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## denalixtc (Dec 13, 2018)

butcher said:


> denalixtc,
> 
> I am having trouble understanding your question(or what you did to what) can you rephrase it?



I put the scrap gold in muriatic acid and hydrogen peroxide...and instead of the remains getting mixed with HCL and nitric acid then precipitating, I skipped mixing the HCL and nitric acid part to dissolve all the gold in to solution. So I have a bottle sitting here with i guess gold in it and hydrogen peroxide, muriatic acid and urea. 

Is there a way to take a step back and remove the sodium metabisulfate and urera out of the concoction i made so I can put the HCL and nitric acid in let it do its thing THEN precipitate with sodium metabisulfate and urea. after that the dust goes into the crucible into my foundry to melt into solid gold.

pretty much i skipped a step and i need to reverse what i did so I can do that step and continue to process. or am I being too confusing?

scap parts get mixes with muriatic acid and peroxide
the filtered gold from that reaction gets mixed with with hcl and nitiric acid
after that, we precipitate to make the gold into a solid again (dust) -- i believe i skipped mixing the gold with HCL and Nitric acid and just added sodium metabisulfate and urea. is it possible to take that step back to add the HCL and nitric acid lol..

im starting to confuse myself.


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## butcher (Dec 13, 2018)

Your question is very confusing.
Check the spelling of your chemicals, use spell check for your posts, make sure you understand the spelling of the chemicals, ate is not the same chemical as ite, these are two different chemicals with different reactions, different oxidation states of the salts of sulfur, sulfite will precipitate gold, sulfates will not.

denalixtc,
You do need to take a great big step back, you are just jumping off a dangerous cliff blindfolded.
Put a clean chunk of copper into any of the toxic dangerous liquids you have now, put it in a safe place.
Put away your chemicals and store them safely (not all chemicals should be stored in the same area they can or will react with each other to form dangers in storage).
Do not throw anything away.

You do not know anything about what you are trying to do, all your doing at this point is putting yourself, your family and all of the people who live around you in danger.

Stop and let's take a big step back.


After you have put your chemicals away safely we can discuss the toxic solution you have made and how to deal with it safely to recover any gold, and protect yourself and others from the dangerous situation and solutions you have on your hands.

We can start this discussion in a new topic or thread of posts. to help you get started after you take your big step back.


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## denalixtc (Dec 13, 2018)

Pretty much i dont think I did the step where I add the Hydrocloric acid and the Nitric acid, to then later add the sodium metabisulfate and urea--- I just added urea and sodium metabisulfate.

sorry the spell check doesnt have any words in the dictionary. Thanks for you help. 



butcher said:


> Your question is very confusing.
> Check the spelling of your chemicals, use spell check for your posts, make sure you understand the spelling of the chemicals, ate is not the same chemical as ite, these are two different chemicals with different reactions, different oxidation states of the salts of sulfur, sulfite will precipitate gold, sulfates will not.
> 
> denalixtc,
> ...


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## denalixtc (Dec 13, 2018)

But step one 
1) i take my scrap I want the gold from and put it in a mixture of muriatic acid and hydrogen peroxide, this takes the gold off the metals its mbonded to.

I filter that out and rinse it a few times with distilled water and a tinybit of hcl.

once i get the clean gold i put it in a flask with hcl and nitric acid, which dissolves the gold into liquid form. I filter that out then let it settle. 

I add sodium metabisulfate and urea and mis and apply low heat and take it off let it get to room temp and settle overnight. 24 hrs later theres gold dust at the bottom of the flask. I extract that and let it dry then put it in my foundry. i put a little borax in and heat it up it melts and out come motel gold. I pour in a ingot to make a brick of gold. 

This time i think i forgot to do the HCL and nitric acid step. so I added sodium metabisulfate with hydrogen peroxide, muriatic acid and urea....and the gold extract of course.



denalixtc said:


> Pretty much i dont think I did the step where I add the Hydrocloric acid and the Nitric acid, to then later add the sodium metabisulfate and urea--- I just added urea and sodium metabisulfate.
> 
> sorry the spell check doesnt have any words in the dictionary. Thanks for you help.
> 
> ...


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## anachronism (Dec 13, 2018)

If you didnt dissolve the gold then pour off the liquid from your raw material and go back to the dissolving step...


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## denalixtc (Dec 13, 2018)

anachronism said:


> If you didnt dissolve the gold then pour off the liquid from your raw material and go back to the dissolving step...



Those were my thoughts I just wanted to make sure that the other chemicals had no reaction with the gold in any way shape or form making my yield smaller.

thank you,

Disposal of the mixture I have should be no different than any other chemical mixture, correct?


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## anachronism (Dec 13, 2018)

It won't hurt to go into your stock pot.


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