Today I started to experiment with hexamine and KNO3 as an experimental rocketry propellant, but whatever mixture ratio I used the mixture was unable to combust. I thought maybe the KNO3 is too wet so I dehydrated it, but the result was the same. Ok, the only possibility was that they chemcial store sold me something else than KNO3. The container was sealed and the chemical symbol right, but who knows in China... I made a aqueous solution of the salt and electrolyzed it. Odor of chlorine...So my KNO3 is probably NaCl or KaCl.
Fortunately I had some silver nitrate in my laboratory. I had used the silver nitrate for former experiments and I know it is really AgNO3. And voila, it started to work. I used different ratios and found that a ratio of 1/3 hexamine and 2/3 silver nitrate works best. (I still need to get the stoichiometric equation for hexamine and KNO3 done).
Attached you'll find the test video of combusting 0.5 g hexamine/AgNO3 mixture.
Attached another video, using a mixture of AgNO3 and magnesium, ignited by a drop of water. The reaction is very heavy. If AgNO3 would be not so expensive, it could be also used as an experimental rocket fuel. The video finally also explains my avatar :)
2010.12.11
It seems that KNO3 definitely works not with hexamine! I bought new KNO3 and made successful blackpowder and candy propellant but it still works not with hexamine, whatever ratio I used. If the KNO3 ratio is too high, it can even not be lit. If the KNO3 ratio is low enough, the hexamine can be lit but burns as usual as it would burn on air.
I also used a mixture of 10% NaNO3 and 90% KNO3 (in China sold as a Chinese traditional medicine). It worked a little bit better than pure KNO3, probably because of the 10% NaNO3.
My suspicion is that hexamine can not be oxidized with KNO3, but with other metal nitrates like NaNO3 or AgNO3. The question is now, why?
