kjavanb123
Well-known member
I am just curios, according to Hokes book, nitric acid and let's say copper, would produce NO2 as the brown fume, can this gas be somehow turn into HNO3? is it possible chemicaly to reuse this to produce nitric acid?
Reusing NO2 from nitric acid
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Noxx
Well-known member
Yes you can.
There are a few patents on this around.
There are a few patents on this around.
kjavanb123
Well-known member
Thnx
what would be a good searching phrase for this? How to make nitric acid??
what would be a good searching phrase for this? How to make nitric acid??
Noxx
Well-known member
I don't know... Most of the patents are on how to neutralize it.
You should be a simple scrubbing column where NO2 could bubble with a lot of surface.
I'm not sure if you could reach a high HNO3 concentration...
You should be a simple scrubbing column where NO2 could bubble with a lot of surface.
I'm not sure if you could reach a high HNO3 concentration...
distill off NO2 bubble into water to make nitric acid, if less than 68% concentration can boil off water untill it reach's 68% further boiling will boil off your 68% acid, if stronger acid needed for some unknown reason, you would need to add 2 times the amount of sulfuric acid and distill off somewhere greater than 80% maybe stronger up to fuming acids.if doing this check on boiling points at concentration, my memory says 103 deg. for 20%, 120 deg for 60%, 83 deg for concentrated 96%, but memory is not good look it up to be sure.
I have been getting back alot of my acids, better to use them to dissolve base metals with than to neutralize them, of course not sure if I am spending more on electrical heat than would cost me to buy them???? OH well, if I realized what I spend getting this gold would probably kick myself.
I have been getting back alot of my acids, better to use them to dissolve base metals with than to neutralize them, of course not sure if I am spending more on electrical heat than would cost me to buy them???? OH well, if I realized what I spend getting this gold would probably kick myself.
semi-lucid
Well-known member
butcher
For the past week or so, I've been working on a design for a rig to regenerate some the nitric from the NO2. But after recent discussion and reading, I've all but abandoned the idea.
Have you done it successfully?
Edit. I'm talking about recovering the brown fumes that occur while dissolving metal.
Thanks.
John
For the past week or so, I've been working on a design for a rig to regenerate some the nitric from the NO2. But after recent discussion and reading, I've all but abandoned the idea.
Have you done it successfully?
Edit. I'm talking about recovering the brown fumes that occur while dissolving metal.
Thanks.
John
yes you can do it this is one process to make nitic acid. bubble them into water.
qst42know
Well-known member
This works to retain and to get the most of your acid. Its not collected for other uses but gets returned to the reaction to keep working. You can use less acid to get the job done.
http://goldrefiningforum.com/phpBB3/viewtopic.php?t=3269&start=0&postdays=0&postorder=asc&highlight=keeping+genie
It works much better than my cheezy lab would indicate. :lol: I need to retake the photos while using a "safe glass" reaction vessel.
http://goldrefiningforum.com/phpBB3/viewtopic.php?t=3269&start=0&postdays=0&postorder=asc&highlight=keeping+genie
It works much better than my cheezy lab would indicate. :lol: I need to retake the photos while using a "safe glass" reaction vessel.
The conversion of the nitric fumes back into nitric acid is possible in a closed system which has been purged with pure oxygen. The system schematic is below, it is a relatively simple system to operate for digesting silver in 50% nitric acid. While in theory only pure oxygen comes out the top of the packed tower (which is 14 feet tall) we still have the discharge exhausted into our ductwork. The reaction tank is stainless steel and the lid is weighted and gasketed to provide a leak-proof seal, forcing the NOx up into the packed tower. The packed tower also has a cooling coil inside so the flow is provided by the oxygen input rate which we judge by the bubble rate coming out the vent at the top of the tower which is submerged about 12” into a water bath.
The reaction is started by adding distilled water to the tank under the packed column deep enough to cover the drain pipe to assure the gas doesn’t bubble out the bottom. This liquid is pumped through the column where it reacts with the NOx and the O2 to make nitric acid, which ends up in the reservoir with the water. We change out the acid in the reservoir when it is about 50% nitric (measured with a hydrometer) and we re-use this acid for the silver dissolve. This setup is probably overkill for all but large silver digestions but when I was experimenting with this technology I had a scaled down rig made up with standard organic lab glassware using a 5 liter vessel which, leaving room for a rise in the reaction, digested 40 ounces of silver. There was no red fume coming out of the top of the glass setup either. That setup would actually make a nice small rig for inquarting 10 ounces of karat with 30 ounces of silver and producing 99% pure gold as a by product. The main contaminant is silver, so if you’re a jeweler cleaning up scrap it can be re-alloyed as is, or cleaned up by melting with some creative fluxing. Then you can drop the silver with salt, reduce it with sugar and use it on the next batch.
The reaction is started by adding distilled water to the tank under the packed column deep enough to cover the drain pipe to assure the gas doesn’t bubble out the bottom. This liquid is pumped through the column where it reacts with the NOx and the O2 to make nitric acid, which ends up in the reservoir with the water. We change out the acid in the reservoir when it is about 50% nitric (measured with a hydrometer) and we re-use this acid for the silver dissolve. This setup is probably overkill for all but large silver digestions but when I was experimenting with this technology I had a scaled down rig made up with standard organic lab glassware using a 5 liter vessel which, leaving room for a rise in the reaction, digested 40 ounces of silver. There was no red fume coming out of the top of the glass setup either. That setup would actually make a nice small rig for inquarting 10 ounces of karat with 30 ounces of silver and producing 99% pure gold as a by product. The main contaminant is silver, so if you’re a jeweler cleaning up scrap it can be re-alloyed as is, or cleaned up by melting with some creative fluxing. Then you can drop the silver with salt, reduce it with sugar and use it on the next batch.
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semi-lucid
Well-known member
Metals
Thanks for the post. The first question that comes to mind is about the materials used. I was under the impression that I needed to restrict my materials to glass only, with the necessary exception of a couple of PTFE gaskets.
The pump is of particular interest. Is it a PTFE lined pump? Centrifugal?
The column is packed. With what exactly?
O2 is key? N2 interferes/ buffers the reaction?
Thanks.
semi
Thanks for the post. The first question that comes to mind is about the materials used. I was under the impression that I needed to restrict my materials to glass only, with the necessary exception of a couple of PTFE gaskets.
The pump is of particular interest. Is it a PTFE lined pump? Centrifugal?
The column is packed. With what exactly?
O2 is key? N2 interferes/ buffers the reaction?
Thanks.
semi
semi-lucid
Well-known member
The other thing is cooling. I had already incorporated cooling into my design, With the possibility of taking the temperature all the way down to 0 deg. C if there was an advantage to the reduced temp.
I've read that nitric is more stable at 0 C, and I thought it might help in the regeneration process.
semi
I've read that nitric is more stable at 0 C, and I thought it might help in the regeneration process.
semi
You can use a paristaltic pump.
Randy
Randy
semi-lucid
Well-known member
Harold_V said:
Does that also apply to AR?
John
The unit I described is for digesting silver which has been inquarted with karat scrap. The system uses only nitric acid and therefore stainless steel is acceptable. the pump is also stainless steel. You could use a peristaltic pump but the hose which comes in contact with the solution wears out periodically and has to be replaced. The reason I don't use a peristaltic pump is that periodically always seems to happen at the worst possible moment.
If you were to build the identical system with materials resistant to aqua regia and pump in chlorine gas instead of oxygen you will recover aqua regia in the tank. The process is more difficult to control because the aqua regia reaction proceeds much more rapidly than the silver digestion I do causing a vacuum which inhibits flow. The simple bubbler I use on top of the tower for nitric dissolves will not work and it has to be replaced with vacuum relief valve and the chlorine flow controlled while monitoring a manometer.
The difficulty in using the system with chlorine, plus the materials needed for an aqua regia resistant setup, make this system a challenge. I don't know what you need as a final product from your refining, maybe you have to use aqua regia, but if you use the setup for nitric and inquart everything with silver you will come out with high purity gold. The gold can be re-boiled in nitric and rinsed and dried to yield a product that may serve your purposes. Read some of Harold's posts, he knows the benefits of inquarting and speaks of it often.
If you were to build the identical system with materials resistant to aqua regia and pump in chlorine gas instead of oxygen you will recover aqua regia in the tank. The process is more difficult to control because the aqua regia reaction proceeds much more rapidly than the silver digestion I do causing a vacuum which inhibits flow. The simple bubbler I use on top of the tower for nitric dissolves will not work and it has to be replaced with vacuum relief valve and the chlorine flow controlled while monitoring a manometer.
The difficulty in using the system with chlorine, plus the materials needed for an aqua regia resistant setup, make this system a challenge. I don't know what you need as a final product from your refining, maybe you have to use aqua regia, but if you use the setup for nitric and inquart everything with silver you will come out with high purity gold. The gold can be re-boiled in nitric and rinsed and dried to yield a product that may serve your purposes. Read some of Harold's posts, he knows the benefits of inquarting and speaks of it often.
Semi
Whoops, I forgot to tell you about the tower packing. The only function of the tower packing is to provide surface area in the column while allowing airflow through the column. The reaction between the O2 and the NOx happens on these surfaces. There are products made for this purpose, they're called tower packing and they're expensive. you can also use bio-balls used in aquariums to provide a similar function for bacteria to colonize. They're expensive as well. Now for the cheap alternatives. Ladies plastic hair rollers, cut up pieces of CPVC pipe. (short half to 3/4 inch slices of inch and a half to two inch pipe) piled up in the column. The diameter and length of the packed area of the column will determine the rate at which you can add metal to be dissolved. Our 18" diameter 14 foot tall tower handles 1350 ounce silver/karat inquarts without a problem or any red fumes leaking out.
Whoops, I forgot to tell you about the tower packing. The only function of the tower packing is to provide surface area in the column while allowing airflow through the column. The reaction between the O2 and the NOx happens on these surfaces. There are products made for this purpose, they're called tower packing and they're expensive. you can also use bio-balls used in aquariums to provide a similar function for bacteria to colonize. They're expensive as well. Now for the cheap alternatives. Ladies plastic hair rollers, cut up pieces of CPVC pipe. (short half to 3/4 inch slices of inch and a half to two inch pipe) piled up in the column. The diameter and length of the packed area of the column will determine the rate at which you can add metal to be dissolved. Our 18" diameter 14 foot tall tower handles 1350 ounce silver/karat inquarts without a problem or any red fumes leaking out.
semi-lucid
Well-known member
I don't want to be a pain with all these questions, but I have a couple more.
The other day, when I asked about using metals in the acid lab, I got responses indicating the fumes would attack all common metals, including 400 and 300 series stainless, as well as being rough on plastics. That and a few other things I read steered me towards glass only.
I had expected to be able to collect the fumes from AR digestion, as well as from nitric digestion. Both processes release the same NO2 fumes do they not?
From Wiki: Dissolving gold in AR
Au (s) + 3 NO3- (aq) + 6 H+ (aq) → Au3+ (aq) + 3 NO2 (g) + 3 H2O (l)
and
Au3+ (aq) + 4 Cl- (aq) → AuCl4- (aq).
I don't see the difference between the nitric fumes and the AR fumes, and I'd rather not produce AR in the re-generator. I'm I reading this Wrong?
Oh no :!: O2 gas is scary enough for me, and I've used up many bottles of it in my day. I was once in an accident where I sustained severe second degree burns to my face and ears. Fortunately I was wearing a cap and safety glasses, so my eyes were not injured. There was a line across my nose where the glasses sat, that went from intact skin to raw meat. It wasn't an explosion involving purified O2, but people reading this should appreciate the fact that O2 can be dangerous. I've been around Chlorine gas to. Pretty raunchy stuff.
On the packing.
I was thinking of the aquarium ball's when I read your post. Someone, I think GSP, mentioned using plastic flowers in a neutralizing scrubber.
The other question is cooling. Do you apply just enough cooling to maintain room temperature, or do you go below room temp? Quoting Wiki: "anhydrous nitric acid should be stored below 0 °C to avoid decomposition" If reduced temps can avoid decomposition, it makes me wonder if reduced temps can promote composition.
Would reduced temps result in N2O4?
http://en.wikipedia.org/wiki/Dinitrogen_tetroxide
Would N2O4 be corrosive to organic plastics? Makes me like glass.
Thanks again.
John
The other day, when I asked about using metals in the acid lab, I got responses indicating the fumes would attack all common metals, including 400 and 300 series stainless, as well as being rough on plastics. That and a few other things I read steered me towards glass only.
I had expected to be able to collect the fumes from AR digestion, as well as from nitric digestion. Both processes release the same NO2 fumes do they not?
From Wiki: Dissolving gold in AR
Au (s) + 3 NO3- (aq) + 6 H+ (aq) → Au3+ (aq) + 3 NO2 (g) + 3 H2O (l)
and
Au3+ (aq) + 4 Cl- (aq) → AuCl4- (aq).
I don't see the difference between the nitric fumes and the AR fumes, and I'd rather not produce AR in the re-generator. I'm I reading this Wrong?
Oh no :!:
O2 gas is scary enough for me, and I've used up many bottles of it in my day. I was once in an accident where I sustained severe second degree burns to my face and ears. Fortunately I was wearing a cap and safety glasses, so my eyes were not injured. There was a line across my nose where the glasses sat, that went from intact skin to raw meat. It wasn't an explosion involving purified O2, but people reading this should appreciate the fact that O2 can be dangerous. I've been around Chlorine gas to. Pretty raunchy stuff.On the packing.
I was thinking of the aquarium ball's when I read your post. Someone, I think GSP, mentioned using plastic flowers in a neutralizing scrubber.
The other question is cooling. Do you apply just enough cooling to maintain room temperature, or do you go below room temp? Quoting Wiki: "anhydrous nitric acid should be stored below 0 °C to avoid decomposition" If reduced temps can avoid decomposition, it makes me wonder if reduced temps can promote composition.
Would reduced temps result in N2O4?
http://en.wikipedia.org/wiki/Dinitrogen_tetroxide
Would N2O4 be corrosive to organic plastics? Makes me like glass.
Thanks again.
John
