# AR Recipe -- Help!!



## dwt9999 (Apr 29, 2007)

I have been reading and found places where, I believe, it said that you mix Sodium Nitrate with HCL to make AR. Another way is to mix Nitric Acid and HCl. 

If all I need to do is mix Sodium Nitrate and HCl, wouldn't it be faster than mixing the Sodium Nitrate and Sulfuric acid and then adding HCl??

Please help to get me streight on this one!!!

Thanks again for your help!!!

Lew


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## toadiesop (Apr 29, 2007)

I'm a little confused on this as well. There's so much great info here but it's all scattered. I was thinking about starting a thread just like this one. :wink: 

So yeah, what he said first, and what exactly is the difference between Nitric and AR?

In other words, what specific task to each do in the process. For example, say I put 20 grams of 18K scrap in Nitric, what would be different than putting that same 20 gram pile into AR?

Hope that made sense.


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## goldsilverpro (Apr 29, 2007)

Catfish just posted an excellent method for using HCl and sodium nitrate. I haven't tried it but it sure sounds right. Catfish's methods are very well thought out and you can trust them. He calls himself an amateur but his research methods are right up there with the best. I also put lazersteve's work in the same category. He has made many posts that will answer your questions with accuracy.

http://goldrefiningforum.com/phpBB3/viewtopic.php?t=352&highlight=

I don't use the name "aqua regia" when talking about HCl and sodium nitrate. To me, aqua regia is HCl plus nitric acid. The two systems are very different in power and speed. With HCl plus sodium nitrate, you have contaminated the solution with a lot of sodium ion and have diluted it with all the water that is needed to first dissolve the sodium nitrate. These things zap it of a lot of it's strength. On the other hand, real aqua regia is full strength and will go after the metals with much more vigor. Using HCl plus sodium nitrate is probably fine on plated materials or gold powder but, for bulky gold alloys, such as karat golds, you need the power of real aqua regia. Sounds like a detergent commercial.

Toadiesop, if you put 18KT in boiling nitric acid for 5 years, it would never touch it. The ring would still be a ring that you could wear and it would still be as bright and shiny as the day you put it in. The nitric doesn't attack the gold but only base metals. In 10KT gold, the gold is only 40% and this lower amount will allow the very hot nitric to penetrate and attack the base metals and silver. This leaves only the gold, as a porous gold powder. With 18KT, however, the gold content is 75%. The gold is so high that it forms an impervious barrier and prevents the nitric acid from penetrating at all.

Aqua regia is a totally different animal than nitric. It actually will dissolve every type of metal involved, including gold and silver, in the alloy. It makes no different what karat the gold is. However, the dissolved silver immediately combines with the chloride from the HCl to form silver chloride. The silver chloride forms a crust on the surface of the karat gold and slows down the penetration of the aqua regia. If the silver content is high enough, the penetration of the acid completely stops. This problem is solved by inquarting with enough silver (preferably) or copper to reduce the gold content to 25%. Then, everything but the gold can be easily be dissolved in hot nitric acid. The remaining gold powder is then easily dissolved in aqua regia.

Hope this answered your questions.


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## Harold_V (Apr 29, 2007)

goldsilverpro said:


> Toadiesop, if you put 18KT in boiling nitric acid for 5 years----- (snip balance of a very good post)



Very well stated. 

If you don't understand what GSP has said here, you'll be in a constant state of confusion. These select words are key to understanding what you may expect, and what is likely the problem when you attempt to refine and don't get expected results. Read those words until they make sense, and you can recite them. They should then be used to make fast observations and decisions when you face unknowns. 

Harold


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## dwt9999 (Apr 29, 2007)

Thanks for the clearification on this topic! I was a little confused.

Lew


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## lmills148 (May 23, 2007)

> Aqua regia is a totally different animal than nitric. It actually will dissolve every type of metal involved, including gold and silver, in the alloy. It makes no different what karat the gold is. However, the dissolved silver immediately combines with the chloride from the HCl to form silver chloride. The silver chloride forms a crust on the surface of the karat gold and slows down the penetration of the aqua regia. If the silver content is high enough, the penetration of the acid completely stops. This problem is solved by inquarting with enough silver (preferably) or copper to reduce the gold content to 25%. Then, everything but the gold can be easily be dissolved in hot nitric acid. The remaining gold powder is then easily dissolved in aqua regia.



I know this is an older post but...
could you first desolve the silver in just nitric acid percipitate it, then add the hcl to make AR ...

not that I have done it either way just looking for an education


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## hilld2000 (Jul 3, 2007)

goldsilverpro said:


> Aqua regia is a totally different animal than nitric. It actually will dissolve every type of metal involved, including gold and silver, in the alloy. It makes no different what karat the gold is. However, the dissolved silver immediately combines with the chloride from the HCl to form silver chloride. The silver chloride forms a crust on the surface of the karat gold and slows down the penetration of the aqua regia. If the silver content is high enough, the penetration of the acid completely stops. This problem is solved by inquarting with enough silver (preferably) or copper to reduce the gold content to 25%. Then, everything but the gold can be easily be dissolved in hot nitric acid. *The remaining gold powder is then easily dissolved in aqua regia.*
> Hope this answered your questions.



If you have dissolved all the metals aprt from the gold, why would you need to dissolve the gold in AR?


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## toadiesop (Jul 3, 2007)

HAHAHAAA!!!



> Sun Apr 29, 2007



Wow, just looking at that date, it's doesn't seem like that long ago......

I was so confused back then.  I sound like an idiot!! :lol: 

Just goes to show how much can be learned here in a VERY short amount of time.

I still can't believe I didn't know the difference between Nitric and AR only 2 months ago. 8)


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## Noxx (Jul 3, 2007)

This forum made me learn very fast too 8)


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## Froggy (Feb 2, 2008)

I dont know the difference, I'll write back in a few months on this thread! :lol: :lol:


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## calgoldrecyclers (Mar 8, 2008)

number one: there is no such thing as sounding like an idiot when you are asking important questions about acid.
number two: AR is, by volume, 25% HNO3 to 75% HCL. only make as much as you need. as soon as the the acids begin "mixing", they will start to decompose each other. never stopper any AR solution, as can cause an explosion with expanding gasses. when the two near colorless liquids come together, it will produce an orange solution. ( if it turns purple or green, RUN!)
hope that helps


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## geekzilla (Apr 13, 2008)

"when the two near colorless liquids come together, it will produce an orange solution. ( if it turns purple or green, RUN!) "

What does purple and green indicate? And if it so bad that you have to run, when can you come back?

If you are preparing your AR inside a fume hood, should one still heed the advice to run?

Thanks.


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## Tredsaw12 (Apr 14, 2008)

> If you have dissolved all the metals aprt from the gold, why would you need to dissolve the gold in AR?




Yes, "Hilld2000" had a good question that many of us "Newbies" are curious about. If you've dissolved all the other metals with the nitric acid and all you have left is gold, why do you need to dissolve the gold? Why not just melt it down at that point? :?


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## Rag and Bone (Apr 14, 2008)

You could melt it down if you are satisfied with impure gold. Redissolving, precipitating and washing the powder will improve the purity.


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## calgoldrecyclers (Apr 14, 2008)

number one: a fume hood is not a safe haven in any sense. a fume hood is designed to evacuate gases produced from various chemicals.
that said, run whenever neccesary. 
a green hue to a chemical reaction of nitric acid, would indicate you have just created deadly chlorine gas.
a purple hue ( imagine liquid amethyst) would indicate you were in the process of developing nitro tolulene. ( not a good thing) 
however, in order produce any of the above, you would have to add chemicals other than the prescribed Hcl for aqua regia. so, you should be safe.
a presence of green while dissolving gold could indicate a high presence of nickel.
the green and purple hues arent an indication of a process gone awry if disolving noble metals. 
however, i am a hobbyist, not a refiner or chemist, so you may want to refer questions to respective persons. 
harold_v , lazersteve or goldsilverpro can probably help you with any refining questions.
hope that helps.
Ezra


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## Tredsaw12 (Apr 14, 2008)

> You could melt it down if you are satisfied with impure gold.



Yes, I guess that makes sense. There could be tiny particles such as glass, ceramic or other metal and debris that won't completely dissolve in nitric acid that would contaminate your gold. If that's the case, then I thought because gold is so heavy that when you melt it, all the contaminants would rise to the top and then you'd just scrape them off the top. No?


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## calgoldrecyclers (Apr 14, 2008)

dissolving gold in nitric wont refine to a pure state. hydrometallurgical refinement is neccesary using aqua regia.


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## Lou (Apr 14, 2008)

calgoldrecyclers said:


> number one: a fume hood is not a safe haven in any sense. a fume hood is designed to evacuate gases produced from various chemicals.
> that said, run whenever neccesary.
> a green hue to a chemical reaction of nitric acid, would indicate you have just created deadly chlorine gas.
> a purple hue ( imagine liquid amethyst) would indicate you were in the process of developing nitro tolulene. ( not a good thing)
> ...




The green yellow of chlorine is something that many who misuse the acid peroxide (HCl and H2O2) process are bound to see. Done outside or in a fume hood, chlorine is relatively tame. More dangerous than chlorine is the nitrogen dioxide and the nitrosyl chloride (NOCl, the active material in aqua regia) that are extremely toxic and can have delayed effects like pulmonary edema and perhaps death. 

As far as the amethyst colour goes, I have no idea what you mean by it or why toluene would even be present in anything we do in refining, whatsoever. Also, it is an orange red compound (like most all aromatic nitro compounds) and you won't form it just from nitric acid--the conditions needed are much more vigorous. Where did you get that information from?


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## calgoldrecyclers (Apr 14, 2008)

Lou,
a friend and chemist from the Bureau of Alcohol Tobacco and Firearms gave me a heads up on the dangers of nitirc and its derrivatives. i believe it was the amethyst color she had described in the process of nitro tolulene ( nitric explosive compounds ). the orange red color is a normal occurence when intermixing nitric acid with hydro chloric acid. i was explaining, or trying to, the effects of green and purple as a finished product. i wasnt trying to let that feller, or anyone else know what to add to nitric that would produce nitric explosives. ( as that can be a dangerous art, better left to experts)


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## Lou (Apr 14, 2008)

She's a chemist with the BATF and she said thatl?! I don't think I've ever seen a purple colour during the nitration of toluene. The conditions are very vigorous and I can safely say that unless someone here has some very exotic reagents, it won't happen. Generally speaking, what we do here has very little danger of explosives formation (as far as nitroesters go) because we aren't using concentrated acids. It can happen with certain organics and just nitric acid, but again, generally speaking, a strong acid is needed to protonate the nitric and give NO2+ (the electrophile which does the actual nitration). I won't say anymore on an open board about this stuff, but Irons is another fellow with professional experience in this science, he may have something to say.

Still, you are quite right to keep organics away from acids! That is a rule we should all try to follow.


Lou


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## Harold_V (Apr 14, 2008)

Tredsaw12 said:


> > You could melt it down if you are satisfied with impure gold.
> 
> 
> 
> Yes, I guess that makes sense. There could be tiny particles such as glass, ceramic or other metal and debris that won't completely dissolve in nitric acid that would contaminate your gold. If that's the case, then I thought because gold is so heavy that when you melt it, all the contaminants would rise to the top and then you'd just scrape them off the top. No?



Non metallic objects do not contaminate melted gold. As you suggested, they are eliminated when the gold is melted. If you have a flux lined melting dish, they would most likely be absorbed by the flux---you would not have need to scrape them off unless there was an excess present. If you were to melt in a crucible with flux, such items would be found in the layer of flux, not affixed to the gold. 

My question is how are these objects getting in your gold chloride solution, so they'd remain in your gold after it's precipitated?

If you follow accepted practice, such materials would have been sorted out in the filtration of your gold chloride prior to precipitation. 

If you are using a procedure different from what I've recommended, you seriously need to explore changes in the way you operate, assuming you have an interest in improving the quality of your gold. 

Harold


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## Tredsaw12 (Apr 16, 2008)

> The silver chloride forms a crust on the surface of the karat gold and slows down the penetration of the aqua regia. If the silver content is high enough, the penetration of the acid completely stops. This problem is solved by inquarting with enough silver (preferably) or copper to reduce the gold content to 25%. Then, everything but the gold can be easily be dissolved in hot nitric acid. The remaining gold powder is then easily dissolved in aqua regia.



Hey Harold, I know you know what you're talking about so please help me with this. In the quote above, the last two lines read: "Then, everything but the gold can be easily be dissolved in hot nitric acid. The remaining gold powder is then easily dissolved in aqua regia."

We were wondering, if EVERYTHING but the gold can be dissolved, then why not just melt the remaining gold powder and be done, instead of dissolving in aqua regia. 

To be more specific, I was thinking that I have a jar of gold plated copper, I was going to just add nitric acid to the jar to dissolve the copper, now wouldn't I have pure gold solids left at the bottom of the jar. Then I could just melt them down into a nice little button.


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## Harold_V (Apr 17, 2008)

Tredsaw12 said:


> > The silver chloride forms a crust on the surface of the karat gold and slows down the penetration of the aqua regia. If the silver content is high enough, the penetration of the acid completely stops. This problem is solved by inquarting with enough silver (preferably) or copper to reduce the gold content to 25%. Then, everything but the gold can be easily be dissolved in hot nitric acid. The remaining gold powder is then easily dissolved in aqua regia.
> 
> 
> 
> ...



Yeah, at a glance it sounds like you could avoid the AR step. I probably should have been more descriptive, or suggested that the gold is pure, relatively speaking. It rarely is. Problem lies in not being able to fully eliminate the base metals. There are many variables that interfere with the end results-----but in theory you could do exactly what you suggest, eliminate the AR process. Fire assayers do it all the time, but they also closely control their button, including eliminating base metals aside from silver, which is done in the cupel. They are absorbed as oxides, along with the litharge that is created in the cupellation process. The button is then inquarted properly, rolled thin (now called a coronet) so the silver can be properly eliminated with nitric and water. Rarely does a person refining expose their material to such exacting processes. They would be dreadfully slow, and not economical in large volumes. 

Given ideal conditions, I have no doubt you could inquart properly, boil in nitric for an extended period of time, then rinse adequately to eliminate all traces of base metals and silver, but doing it routinely would be a tall order. It's far easier to get the gold as pure as you can with the preliminary washes and rinses, then to dissolve it so you can precipitate it and (hopefully) leave the trace contaminants behind. Even that doesn't guarantee 4 9's, and rarely does, if for no other reason, drag-down.



> To be more specific, I was thinking that I have a jar of gold plated copper, I was going to just add nitric acid to the jar to dissolve the copper, now wouldn't I have pure gold solids left at the bottom of the jar. Then I could just melt them down into a nice little button.



You won't be the first to think it will work, and you damned sure won't be the last. Again, the problem is that while you've eliminated the vast majority of contaminants, you don't get them all. 

I encourage you to try what you propose, so you'll get a firm understanding of what the end result will be, and what gold looks like when it's not quite pure. It will do no harm, and it's easy to re-process the gold to achieve a higher level of purity, although not quite as easy as dissolving those nice, well washed, foils. 

I fully expect the gold that comes from this operation to be contaminated with traces of lead and tin, plus some copper and nickel. The surface of the gold will be somewhat mottled, and not brilliantly shiny as it can be. It also will likely not form the large, broad crystalline structure characteristic of pure gold----and is likely to form an oxide scale. Pure gold will melt without flux and cool with a bright surface without a trace of oxidation. Any contamination pretty much assures that will not be the case. 

For the record, I refined all of my gold two times to eliminate traces of contaminants that hitched a ride through the first processing, even after washing well. Getting gold pure isn't easy, although GSP claims to have a process that pretty much assures it will be. I'm not privy to how it works, but he's talking about putting a book together that will include the process. Up to now, he's not been willing to share the information. 

Harold


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## Tredsaw12 (Apr 17, 2008)

OK...well I guess that explains it. 

Thanks Harold. That question was bugging me for weeks.


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