Dear yosef Scolnik,
There is no problem of mixing of pure urea and pure Ammonium Sulphate. However if the Ammonium Nitrate is present then it can happen.
Ammonium Nitrate is heating or any ignition source may cause violent combustion or explosion. Ammonium nitrate reacts with combustible and reducing materials as it is a strong oxidant although it is mainly used for fertilizer, it can be used for explosives. It was sometimes used to blast away earth to make farm ponds. Ammonium nitrate is also used to modify the detonation rate of other explosives, such as ammonia-based dynamites,
A blend of urea and ammonium sulphate is being touted as an alternative to ammonium nitrate. A 50/50 mixture of urea (46-0-0) and ammonium sulphate (21-0-0-24) produces a blend with an analysis of 33.5 N-0-0-12 S. In a 50/50 mix on a per ton basis there are 460 lbs nitrogen from urea and 210 lbs nitrogen from ammonium sulfate which gives the mix 670 lbs total nitrogen/ton. Sixty-nine percent of the nitrogen is from urea and 31 percent of the nitrogen is from ammonium sulphate.
Regards,
Prem Baboo
Thanks dear Prem Baboo
There is a point I dont understand - If there is no presence of ammonium nitrate - even in small amounts -then ammonium sulphate and Urea will not ignite ?
Dear Yosef Scolnik
When heated to 147 ° C ammonium sulphate decomposes into the corresponding bisulfate NH4HSO4 and ammonia according to the scheme:
When the temperature rises above 500 °C ammonium bisulfate boils with decomposition at sulfur dioxide, ammonia and water:
Ammonium sulfate is oxidized to molecular nitrogen, strong oxidizing agents, such as potassium permanganate. Therefore, ammonium sulfate predominate reduction properties.
Thus, urea is also strong reducing agent is, but not oxidant. It is even used in cleaning systems from nitrogen oxides:
Therefore, in the absence of your mixture outsider’s strong oxidants, it is not flammable and explosive.
Regards,
Professor Pavel Kudryavtsev
Dear Pavel
Thank you so much
Suppose there is a small amount of Aluminium Nitrate as an impurity in the aluminium sulphate - would that cause the mixture to ignite after all? some water is present too
Thanks again
best
Yosi
Dear Yosef
For the system of ammonium sulfate and urea, with the addition of ammonium nitrate, passed in the fuel state, it is necessary a certain critical ammonium nitrate content. This critical value must be determined experimentally. The presence in this system of water impurities will reduce its combustion properties.
Regards,
Pavel
Hi Pavel - I analyzed the mixture - and found 3.8% 38mg/gr ammonium nitrate (actually the nitrate was found ). As you kindly answered before - the amount that will cause ignition has to be determined -Still -do you have a guess if its plausible that this amount can cause ignition
Thanks again
Dear Yosef,
Reply to a question about the possibility of ignition of the mixture, with this content of ammonium nitrate, you can only experimentally. This requires prepare mixtures with different contents of urea and thermogravimetric analysis to make for them. Experiment anything will show.
Regards,
Pavel
Dear Prem Baboo:
I ask you again - if possible - lets say you sell a mixture of Urea , Ammonium Sulphate and 4% Nitrates -say Ammonium nitrate but may be other nitrates, Do you think that at least you will warn the buyer that this mixture may ignite ?
Thank you again for your attention
yosi scolnik
Dear Yosef,
Yes, of course, although the possibility of ignition is low, but, just in case, better to warn customers about the possibility.
Sincerely, Pavel
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