How dangerous is Aqua regia

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Jewelers carefully wafting the scent from their AR while not actively using it differs rather a lot from getting a good dose of its fumes while actually working with it.

/ Just say NO.
 
Even whit a small amount of the acid and a very reactive metal can produce; a very dangerous reaction.

[youtube]http://www.youtube.com/watch?v=-S9w_40QJ9Q[/youtube]
 
Very impressive. Though, the guy had no heavy gloves, I wonder how many times he will survive those dangerous experiments. Nothing anybody should try, is making such experiments for the government, like BAM in germany. What is the equivalent to the Bundesamt für Materialprüfung in the USA?
 
solar_plasma said:
Very impressive. Though, the guy had no heavy gloves, I wonder how many times he will survive those dangerous experiments. Nothing anybody should try, is making such experiments for the government, like BAM in germany. What is the equivalent to the Bundesamt für Materialprüfung in the USA?
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that would be a couple of different agencies here like http://en.wikipedia.org/wiki/Occupational_Safety_and_Health_Administration and http://en.wikipedia.org/wiki/Epa
 
martymcfly said:
Ok so this is probably a no brainer. Its really dangerous . but im wondering just how much of this stuff do you have to inhale before your going to see problems?

For instance would getting a whiff from mixing a small amount like 10ml do you harm or would you have to be mixing a litre of the stuff and having serious smoke before its a proper danger?

Has anyone on here had any accidents where they have been exposed and felt ill due to it?
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Any amount of unnecessary exposure is unacceptable. It's accumulative. Each time you are exposed would make the next more dangerous. If you take the proper precautions and being as safe as is possible, you shouldn't have too much to worry about barring acts of God.

Scott
 
Magiskt has not visited the forum since November of 2013. You might try sending a private message.

Time for more coffee.
 
No need to filter the fumes. While nitric fumes are very deadly in an enclosed space, they dissipate quickly. If your fume hood vents out through your roof (20’+- agl) there’s nothing to worry about.
 
cejohnsonsr1 said:
No need to filter the fumes. While nitric fumes are very deadly in an enclosed space, they dissipate quickly. If your fume hood vents out through your roof (20’+- agl) there’s nothing to worry about.
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Yeah, to the certain point. Thy disperse quickly, but downside is they can be smelled in very low concentrations :) and thus dragging unwanted attention.
 
Here in the US you can apply for and be granted a “de minimus” status which usually means you use less than 10 pounds of Nitric acid a day. The catch is if anyone complains about the smell, even if your usage is under the limit, you still need to scrub it.

cejohnsonsr1 said:
If your fume hood vents out through your roof (20’+- agl) there’s nothing to worry about.
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Maybe the 20’ above ground level works in suburbia or rural settings but in a city it’s much different. I knew a refiner in a single story building who had much taller buildings on both sides. He had to move because both neighbors could look out their windows and look at his stacks. He knew sooner or later he would piss someone off.
He moved to a tall building on the top floor for that very reason.
 
4metals said:
Here in the US you can apply for and be granted a “de minimus” status which usually means you use less than 10 pounds of Nitric acid a day. The catch is if anyone complains about the smell, even if your usage is under the limit, you still need to scrub it.


Maybe the 20’ above ground level works in suburbia or rural settings but in a city it’s much different. I knew a refiner in a single story building who had much taller buildings on both sides. He had to move because both neighbors could look out their windows and look at his stacks. He knew sooner or later he would piss someone off.
He moved to a tall building on the top floor for that very reason.
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In utmost simplification, nitric is just an oxidant. Hard to get, causing problem anywhere it appears in classic AR refining scheme. NOx gasses, need for de-oxidation of nitric residues...

Chlorine is much friendlier in these terms, simultaneously order of magnitude more dangerous. Cl2 cylinder is out of option for majority of refiners... But small chlorine generator/electrolyzer ? Produce only that much you need, feed would be HCl or some metal chloride. RuO2 electrodes are expensive but purchasable...

Just a thought. It would be more expensive than nitric, but for many people it would suit their needs.
 
Atomizing the material allows for easier digestions with Hydrochloric Acid and chlorine. A convenient source of chlorine is sodium chlorate. Just keep
It from getting too hot and running away. Keep
it around 50°C and you can control it easily. Ice is your friend.
 
4metals said:
Atomizing the material allows for easier digestions with Hydrochloric Acid and chlorine. A convenient source of chlorine is sodium chlorate. Just keep
It from getting too hot and running away. Keep
it around 50°C and you can control it easily. Ice is your friend.
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I need to get familiar with chlorate dissolution, as it can easily be made by electrolysis in bulk. As I have quite a bit of fear using chlorates in general in acid media, from one incident with ClO2.
Are you dosing the chlorate directly to the reaction mixture or you have some separated dedicated generator ? If yes, which acid you use to liberate Cl2 and chlorine oxides ?
 
I have always used it as a powder added directly to the reaction. I always use the Hydrochloric Acid at azeotrope strength for the process. With care, attention to the temperature, and slow additions, it produces an aqua regia like reaction that can be stopped by stopping the additions and cooling. This is only doable with finely divided feed material, such as atomized alloy.

Storage is a big concern, keep it dry and away from organics and keep it from interaction with the environment.

orvi said:
As I have quite a bit of fear using chlorates in general in acid media, from one incident with ClO2.
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Say a little more about your encounter with the dioxide.
 
4metals said:
I have always used it as a powder added directly to the reaction. I always use the Hydrochloric Acid at azeotrope strength for the process. With care, attention to the temperature, and slow additions, it produces an aqua regia like reaction that can be stopped by stopping the additions and cooling. This is only doable with finely divided feed material, such as atomized alloy.

Storage is a big concern, keep it dry and away from organics and keep it from interaction with the environment.


Say a little more about your encounter with the dioxide.
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Yeah, that is the way. It was presented to me very similarly by my boss once he talked about it´s use from his early days in refining.
Solid NaClO3 or KClO3 is OK to store in glass containers for practically infinite period of time. But of course, apart from any organic or reducing agents :) I once produced it by electrolysis, when I was young and interested in pyrotechnics :)

ClO2 background

I knew about ClO2 possibilities of formation, as I few times intentionally produced some by acid decomposition of chlorate. Light is all it need to spontaneously pop or "explode", even in not closed space. Also very very nasty gas, I hate that smell very much.
I was using chlorate to oxidize Pd to red salt with NH4Cl. Solution was fairly concentrated, but I didn´t realized HCL content isn´t very big. It does not worked at all, so I decided to heat it up on the hotplate to facilitate it... And yeah, I should guess what can it become. As I added relatively fair portion into the beaker, and started heating, in PGM enviroment it somehow catched very rapid reaction, with evolution of yellow gasses and then it started popping :D I barely managed to put watchglass on top and quickly getting it off heat. But as it popped, watchglass danced on the top of the beaker and it spitted the expensive solution quite vigorously. Luckily, also as you say, as it cooled below that threshold temperature, it calmed down. Practically nothing bad happened, practically no spill at all... But it is still in my head, that bouncing watchglass sound and stuff... So I didn´t used it for anything from the time it happened to me. Luckily, it does not have a big explosion force, more scarry than really dangerous (as explosive). After the incident, I realized that putting watchglass on top wasn´t very good idea in terms of concentrating explosive gas inside :)
 
Sometimes heat is good, sometimes pressure is good, sometimes both are good. And sometimes all of the above are bad! But every reaction is different and that is what you learn with first hand experience.

I am glad you escaped with your health intact and a lesson learned. That’s the important part.
 
goldsilverpro said:
A friend of mine just got a fairly large burn, probably 2nd degree, on his arm from working, for a short period of time, over the hot red fumes produced from dissolving copper with nitric in a bucket.

NO2, the red fumes produced from dissolving metals in nitric or aqua regia, rats seemingly have an LD50 of 88 ppm over a 4 hour exposure. That's a little less than 1 part NO2 per 10,000 parts of air. LD50 (lethal doze for 50%) means that 50% of the rats exposed to that dosage will die. I also read that the symptoms may not show up for 72 hours.

Although the gases produced from just mixing AR are noxious and toxic, the greatest danger is the NO2 gas produced when dissolving metals.
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Excuse me, I have a question for you. What is AR?
 

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