AR Recipe -- Help!!

[dwt9999]

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

 

[toadiesop]

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.

 

[goldsilverpro]

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.

 

[Harold_V]

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

 

[dwt9999]

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

Lew

 

[lmills148]

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

 

[hilld2000]

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?

 

[toadiesop]

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)

 

[Noxx]

This forum made me learn very fast too 8)

 

[Froggy]

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

 

[calgoldrecyclers]

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

 

[geekzilla]

"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.

 

[Tredsaw12]

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? :?

 

[Rag and Bone]

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

 

[calgoldrecyclers]

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

 

[Tredsaw12]

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?

 

[calgoldrecyclers]

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

 

[Lou]

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

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?

 

[calgoldrecyclers]

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)

 

[Lou]

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