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Rosco Bodine
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What is the purpose of the process? It may help me to understand what you are trying to accomplish.
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kilowatt
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To produce nitric acid and ammonia from ammonium nitrate without using up any other reagents or materials. For example react magnesium oxide to
ammonium nitrate to produce ammonia and magnesium nitrate, then decompose the nitrate to yield nitric acid synthesis gases and magnesium oxide, which
is used again in the next reaction pass. For the first reaction pass I could use faster methods like the magnesium carbonate, which I have enough
materials to cheaply produce over 100 moles of. However I am interested in making far more nitric acid than that, so I will need a more cyclic route
(like using the MgO directly) to continue.
I was going to use aluminum with electrolytic methods, hence the title of this thread (I had an older thread about using copper), however magnesium is
obviously a better choice.
The nitric acid will be in turn used to make lead nitrate from scrap, thus separating the alloy since tin will form oxide and precipitate (its nitrate
decomposes in water). Antimony should precipitate as well. Lead nitrate can then be decomposed to regain the nitric acid, and leave lead oxide for
smelting.
Magnesium nitrate itself should also be an excellent oxidizer for solid rocket propellants.
The mind cannot decide the truth; it can only find the truth.
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Rosco Bodine
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Decomposing Magnesium Nitrate will require very high temperatures, and recycling the decomposition gases back to nitric acid may not be so
straightforward as
reacting with water.
If experiments with producing nitric acid more efficiently
using the nitrate/sulfuric acid reaction is a goal, getting
2 moles of nitric acid per mole of sulfuric, avoiding the
bisulfate byproduct ....then magnesium nitrate makes sense.
If experiments with alternate dehydrating agents for nitrolysis and nitration is a goal, then magnesium nitrate
or the double salt with ammonium nitrate, in solution in strong nitric acid makes sense.
But if making lead nitrate is the goal, then there are probably easier ways, already outlined in the preparation of lead salts thread, and for a
scheme involving ammonium nitrate as the nitrate donor magnesium nitrate
as an added step seems more trouble and no advantage,
which doesn't make sense.
Did you try low voltage ac on lead scrap or amalgamated
lead scrap in moderately hot aqueous NH4NO3?
The frequency of the AC may have to be lowered to
something like one cycle every two minutes, using a
double pole double throw relay driven by a timer to
make square wave AC from DC. What I was thinking
is to cycle it at a rate which allows formation and saturation of an amalgam film with ammonium amalgam, decomposed on reversing polarity in the warm
solution.
It might work even without an amalgam, or it may require a divided cell or a pumped liquid mercury electrode with
the ammonium amalgam decomposed in a separate compartment. But these things are definitely worth looking at if you are processing large amounts of
scrap lead.
Some of the straight chemical methods using HCl as a cheap acid source and a nitrate would probably also be more economical than any route using
magnesium nitrate.
I just don't see the recycling loop you are contemplating there as being viable.
Using HNO3 gotten from a distillation of HCl plus Magnesium Nitrate is another possibility which might be worth looking at....I'm not sure how
that particular reaction efficiency would work out if at all. But for sure the conversion of even low concentration H2SO4 like battery electrolyte
reacted with Magnesium Nitrate would
provide a pure distilled HNO3, and the byproduct Magnesium Sulfate could be recycled via Magnesia Alba
and Ammonium Nitrate......the only byproducts of the loop
would be glauber salt and ammonia. If this is a battery recycling project, that provides utilization of the battery electrolyte as an active part of
the recycling, eliminating any need for its disposal by using it in the recycling of the lead and lead oxide and sulfate.
If thermal decomposition gases from the lead nitrate are neutralized by alkali, you will get a mixture of nitrates
and nitrites. Or you could use those "nitrous gases" for other interesting purposes, much more easily than recycling them to nitric acid. Plan on a
catalytic converter
being part of the process if recycling the nitric acid is desired.
[Edited on 17-8-2008 by Rosco Bodine]
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kilowatt
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I have experimented with electrolytic lead nitrating methods as outlined in that thread. I haven't tried 60Hz AC but I have tried DC and low
frequency (one square cycle every few minutes) AC. I believe the electrolysis eats up most of the ammonia, converting it to hydrogen and nitrogen
which cannot be easily recycled without the Haber Process. A lot of ammonia does escape however, and I have not yet tried to capture it in amalgam,
but that may be a good method. I have not tried any divided cells yet but have some ideas in the works for that and will continue experimenting.
Equipment cost is an issue too though and I could probably get enough nitric acid to do all the lead from the magnesium nitrate process for cheaper
than I could build such specialized cells especially with amalgam pumps and such. What I really need for an electrolytic method to work is a way to
keep the lead ions in the anolyte while allowing ammonium to pass into the catholyte. As mentioned in the lead salts thread, this is what is needed
for lead nitrate to be formed with any degree of efficiency, since the lead tends to deposit onto the cathode otherwise. The reaction only proceeds
if ammonia is removed while lead and nitrate are retained (or ammonium is at least kept separate from lead and nitrate.
I have tried lead amalgam in fused ammonium nitrate as well but it was an extremely slow reaction.
The decomposition of magnesium nitrate is not that high in my opinion; something over 300°C and I intend to do it in a RBF with a heating mantle. I
carried out the decomposition earlier at a small scale, and it was quite complete. The vapors will have to be cooled before dissolution into water,
but with excess air bubbled in the conversion to nitric acid should be complete; this is how nitric acid is made in industry from NO2. I am not aware
of any side reactions in the magnesium nitrate decomposition (for example oxygen and nitrite); it should be straight 4NO2/O2 gas coming out, as well
as water of hydration from the magnesium nitrate. Once you have nitric acid, making lead nitrate or any other metal nitrate could not possibly be
easier, as it is as simple as putting the metal into the dilute acid and letting it dissolve.
I do intend to catalytically oxidize much of the ammonia I get from the ammonium nitrate to NO2 of course, thus converting the entirety of ammonium
nitrate to nitric acid. Such a catalyst should not be required at all with the 4NO2/O2 reaction gas however. That stuff definitely forms nitric acid
with simple dissolution (better yield gotten by adding excess oxygen though).
A process which ends with glauber's salt can be considered a waste of sulfate in my opinion. In order to regain sulfate from it, high temperature
reduction with carbon as well as catalytic oxidation of SO2 to SO3 are required. Once my sulfuric acid from calcium sulfate project is further under
way (which involves exactly those two things) it would clearly be the superior method, but for now I am looking for something that does not use
sulfuric acid.
Both magnesium and lead nitrates can be considered a ready source of NO2 as well as a ready source of oxygen (the two gases are most easily separated
by condensation of N2O4), which can be quite useful to have in the lab. They are also much nicer to store than nitric acid itself. Magnesium nitrate
is a powerful oxidizer and I want to try it in some rocket propellants as I mentioned. Another fact is I am quite low on nitric acid at the moment
and need more before such a time that I can develop and electrolytic lead nitrating method.
Also for the lead refining process, the nitric acid only needs made once really. From then on the lead nitrate can be decomposed and the vapors
recycled.
[Edited on 17-8-2008 by kilowatt]
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Rosco Bodine
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You can convert your glauber salt back to sodium carbonate using lime and have gypsum as the waste.
The economics of your chosen scheme are certainly related to scale, and to whatever use certain byproducts may be applied. If you are processing and
salvaging a
few dozen batteries, closing the process loop will be more expensive than simply enduring some waste by products
as the cost of doing business. Of course if you are recycling thousands of batteries as a continuing business operation, then a different rationale
applies to the investment when a net return and profit is possible for
the extra trouble of closing the loop. It may still come down to the cost of electricity and heating requirements
not being favorable economics in comparison with generating some waste byproduct or low value byproduct,
which still represents a profit or even a reduced loss for
the processing and reclamation of what would otherwise be hazardous waste. By that of course I mean that non-hazardous waste is still a profitable
outcome for having salvaged a hazardous component having some value as
reclaimed material, it is entirely acceptable to generate a
benign byproduct as waste (more or less) in the bargain.
[Edited on 17-8-2008 by Rosco Bodine]
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kilowatt
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I am recycling perhaps 150-200lbs (400 moles give or take) of scrap lead which I bought years ago at recycling centers. It contains random items,
wheel weights, weather stripping, solid ingots, etc, which I melted down into ingots. It is hard lead and my main goal is to separate it into
primarily lead, tin, and antimony. Since the prices of those have gone up several times since I bought the scrap I would like to get it refined, and
I wish to have those items stocked in my periodic table in pure form, for all manners of chemistry. This isn't really for business; I just want a
method that has relatively straightforward steps, is not wasteful or expensive, and is more interesting than the more traditional methods.
Another consideration is that once the magnesium nitrate is decomposed inside a glass vessel of whatever sort, it absolutely cannot be removed. It
will be entirely cemented in and insoluble. The only options from there are to dissolve it with acid (allowing a precipitation as carbonate again but
at the cost of said acid's anions) or to react it once again directly with ammonium nitrate, using the boiling to agitate and loosen the crust. The
latter is more favorable for large volumes, but as I mentioned before the nitric acid really only needs to be generated once and the it's all up to
the lead salts. Since lead nitrate does not form highly bound hydrates I will be able to decompose the anhydrous product in a steel vessel, grinding
up the resulting litharge and smelting it. However to generate for example 250 moles of nitric acid with the magnesium method while carrying out the
precipitation each time, I would go through no less than 7 gallons of muriatic acid - unacceptable.
I have not yet done a reaction to completion of PbO and ammonium nitrate; if it is not too prohibitive that may be a good method for generating the
further nitric acid.
[Edited on 17-8-2008 by kilowatt]
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Rosco Bodine
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With that quantity you shouldn't even bother trying to close the loop, just do whatever is convenient, and don't sweat the waste. If you had a
thousand times that amount, it would still be the rule, unless it was a cyclical task.
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kilowatt
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What is convenient in my case is a method that produces hundreds of moles of nitric acid but does not use up hundreds of moles of sulfuric acid or
hydrochloric acid, or any other commodity for that matter. Can you imagine what they would do if I asked for 10 gallons of battery acid?
The lead is no problem since the nitric acid from it is very easily recycled, but I need enough nitric acid that I can process all the lead in just a
few batches and still have nitric acid available for other things.
[Edited on 17-8-2008 by kilowatt]
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Rosco Bodine
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If you asked for ten gallons of battery electrolyte, it shouldn't even raise an eyebrow. The guy in the battery shop would go to his pallette stack
of cardboard boxed
five gallon polybagged "Qual" and take two boxes and
hand them to you. Probably he would ask you if you would like to take advantage of a special discount for a dozen or more.
I think you are multitasking this project too far to be practical ....but feel free to ingeniously prove me wrong.
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DubaiAmateurRocketry
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I think salts of [Al(N2H4)3]3+ exists, However I cant find any information on it. This cation gives very high amount of hydrogen(near 10%) with
possible high density
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