kilowatt
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monoammonium phosphate
I am trying to obtain or synthesize monoammonium phosphate. It's for phosphate bonded investment casting mixes so high purity is not a concern. I
have bone ash and ammonium nitrate on hand, and so have been looking for a simple route from that. By adding 4 moles of HCl to a mole of bone ash
(Ca3(PO4)2) and 2 moles of ammonium nitrate, (NH4)H2PO4 should be the first to crystallize from the solution upon cooling. The remainder should be a
mixture of calcium nitrate, calcium chloride, and ammonium phosphates/phosphoric acid. I tried this last night on a 1/10th mole scale and obtained
yellowish granular crystals from a highly concentrated solution boiling. I have yet to analyze the product or make an estimate of my yield. It would
be ideal if I could recover calcium nitrate from the solution as well.
A summary of the reaction I am attempting is:
Ca3(PO4)2 + 2NH4NO3 + 4HCl --> 2(NH4)H2PO4 + Ca(NO3)2 + 2CaCl2
[Edited on 23-6-2009 by kilowatt]
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Eclectic
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Available in good purity as greenhouse grade fertilizer in 55lb bags.
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kilowatt
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Not around here or at a price I can afford.
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Paddywhacker
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Try home brewing suppliers of hydroponics suppliers.
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kilowatt
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I need this soon, like this week. I live in a small town with no resources like that. Even if I were to drive 100 miles to Billings, it would be
unlikely that I could find any pure ammonium phosphate fertilizer; it is usually found in mixtures.
Has anyone here actually tried to find and purchase this stuff on the internet? It isn't that easy to find, and is unreasonably expensive when you
do. I really don't have money to be spending on chemicals right now and am trying to get some stainless steel casting done. A chemical route using
what I have is really the only viable option right now. It has to be simple and not wasteful of my general purpose reagents, though.
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not_important
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Did you consider the following reactions:
NH4NO3 + HCl => NH4Cl + HNO3
HNO3 + 3 HCl => NOCl + Cl2 + 2 H2O
The NOCl and Cl2 can react with the ammonium ion.
Di-ammonium phosphate is used in brewing as a yeast nutrient. Mono-ammonium phosphate is available as ag-grade, Simplot is one manufacture with
distributors in your area.
DAP converts to MAP on heating, and MAP to the pyrophosphate; that makes me wonder if a mixed ammonium phosphate could be used.
If you can get trisodium phosphate consider using it instead of bone ash. Alternatively you might boil a solution of ammonium sulfate for awhile,
which causes it to lose ammonia to form some of the acid sulfate, then add a hot slurry of bone ash to that and boil further.
[Edited on 24-6-2009 by not_important]
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kilowatt
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Thanks for the reactions and ideas. I think if I went with an acid ammonium sulfate route I would simply add sulfuric acid to ammonium sulfate.
Another option I am considering is the acetone extraction of phosphoric acid from the dehydrated solids after an acidifcation of bone ash with HCl, to
obtain phosphoric acid. I read a patent that discusses a method like this, and I have found that (completely contrary to every MSDS I've read)
anhydrous CaCl2 is insoluble in acetone. By obtaining phosphoric acid itself I have a more useful reagent and can easily convert a given amount to
monoammonium phosphate by adding ammonia (derived from ammonium nitrate or sulfate by NaOH). The cost of all these reagents is still less than any
source of monoammonium phosphate I have found (except for the large bags) and I actually have good use for the biproducts in other aspects of my
current work (making nitric acid or SO3 from the respective sodium biproduct salts). The main problem with any of this is boiling off the large
amounts of water and excess HCl which will take some serious time in my still.
[Edited on 24-6-2009 by kilowatt]
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Eclectic
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http://www.markertek.com/Tents-Canopies-Folding-Chair/First-...
http://www.playfairtoys.com/product/Grow-Colossal-Crystals
http://www.labsafety.com/SENTRY-Tri-Class-Dry-Chemical-Fire-...
http://www.simplot.com/agricultural/plant/mono_amm_phos11520...
http://cgi.ebay.com/Ammonium-Phosphate-Monobasic-FCC-One-Pou...
http://shop.ebay.com/items/?_nkw=phosphoric+acid&_sacat=...
[Edited on 6-24-2009 by Eclectic]
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argyrium
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Coincidentally, we just had our yearly fire extinguishers serviced. I don't recall how often but every several years, they have to empty the tanks
and pressure test them.
I asked the fellow what they did with the MAP they discharge in the process. It is not reused, so I asked for some. He later returned to our business
and dropped off ~ 40 lbs of it.
The very finely ground material has been obviously treated in some way as it is extremely free-flowing and does not mix easily w/ H2O. I would
suspect a silicone or perhaps a wax in addition to other free-flow additives.
If you have a fire extinguisher service in your area, this might be a good source. The hydrophobic coating likely be easily removed with non polar
solvents.
____________
All truths are easy to understand once they are discovered; the point is to discover them.” Galileo Galilei
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kilowatt
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Is there any chance you could spare some of it for a fellow chemist? Around here used/outdated fire extinguishers are simply disposed of. I will
definitely keep my eye out though. New fire extinguishers as suggested by others are out of the question.
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watson.fawkes
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Quote: Originally posted by kilowatt  | | I need this soon, like this week. I live in a small town with no resources like that. Even if I were to drive 100 miles to Billings, it would be
unlikely that I could find any pure ammonium phosphate fertilizer; it is usually found in mixtures. |
In the
ag trade, they just call it MAP and has the NPK designation 11-52-0. It's sold just like that. See also this page on phosphorus fertilizers, which contains some information on industrial manufacture. Your local feed store may not even know the name, but
they'll be able to sell to you by the numbers.
I just got off the phone with my local feed store. They carry it in 50 lb bags for $24, quantity 1, retail.
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