marks265 Posted January 18, 2008 Posted January 18, 2008 When you read an MSDS for KNO3 it has a value of 334 degrees F, if I remember right, for a melting point. How does this compare to trying to disolve it into solution. In other words water boils at 212 degrees F, does KNO3 liquify at 334 degrees? What exactly does "boiling point" refer to?What would it take to disolve it into a usable solution if possible to homogenize KNO3 with sulfur and charcoal but without water. Ball milling is used to do this at a particle level but does melting KNO3 make it smaller yet and then attach to the other two? Maybe disolving KNO3 is like disolving a rock? I donno.
FrankRizzo Posted January 18, 2008 Posted January 18, 2008 Melting point refers to the solid/liquid phase transition temperature (ex. ice melting to water - 32F). Boiling pt is the liquid to vapor transition temperature (ex. water to steam - 212F). In theory, since the lowest ignition temperature ingredient is sulfur @ 470F (melts at ~240F), you *could* melt the potassium nitrate and sulfur and mix it with the charcoal in a liquid phase. In practice however, the sulfur will make an incredible stench and is liable to ignite unless you have absolutely even heating. Use a ball mill, or the CIA process instead.
Mumbles Posted January 18, 2008 Posted January 18, 2008 Without even heating you are also liable to partially decompose potassium nitrate into potassium nitrite. There are other methods to actually get a pure yield of potassium nitrite, but that isn't important. Technically speaking, dissolved in a liquid is the smallest possible particle sizes. The issue with the CIA method is getting it out of the solution in the smallest possible particle sizes, and keeping loses to a minimum.
asilentbob Posted January 18, 2008 Posted January 18, 2008 Also I'm pretty sure sulfur has a much lower auto ignition temperature. IE the temp that if raised to and exposed to air it will catch on fire... However... that is exposed to the low concentration of oxygen in the air... sulfur and potassium nitrate... I would think that the sulfur would catch and both would decompose forming a very stinky poisonous smoke bomb... However at those temps... could be much worse...
FrankRizzo Posted January 18, 2008 Posted January 18, 2008 Yeah, you are likely spot-on. The MSDS for rubbermakers that I read stated ~470F. Sigma-Alrich's site lists 374F for reagent grade. That's quite a discrepancy and is probably due to the different allotropes that sulfur can be found as. In any case, it's not a good idea from both a safety and efficiency standpoint to melt the components of black powder together. If it were, industry would have adopted the method years ago.
marks265 Posted January 19, 2008 Author Posted January 19, 2008 Good comments! Very much appreciated. Yes, I use the stand by ball mill and it works, it's your average cheapy. It takes awhile with a cheapy rock tumbler but I'm working on that. Not afraid to admit it. I tried the CIA method once and I think I probably walked away with a grade of C-. Pretty bad especially if you don't know what your looking at. So on to the next angle. I'm hoping this will raise an eye brow or two.This is relating to the black powder thread but I still think this is a cooler chemistry way of looking at things. Here we go. The CIA method has a certain amount of danger to it as pyro in general I guess. But me and my mechanical way of looking at things had to put a twist on it. When I failed my project I saved the liquid after pressing and was dismayed with the amount of crystalization that occured in the liquid. I had my black powder drying and was hoping for the best and returned to the liquid and saw a good amount of my KNO3 in the waste-crystalized. Heard this before I'm sure. So me and my thinking of how to best accomplish "homoginization" came up with a "food saver". I put my comp. in a food saver bag(unsealed) with minimal water and then boiled it like "seal a meal" or something. Then when the water was boiling and after several stirrings I sealed the food saver bag. I think we all no what happens when the bag cools right? I have actually made black match using full unwound spools of string this way and I thought it turned out pretty good. It takes a couple of heating and cooling cycles though to compress the string. After it cools cut the top of the bag and draw another vacuum after reheated and reseal. VACUUM IMPREGNATED!!!! Did I do any good or am I a legend in my own mind? Anyone tried this??
asilentbob Posted January 19, 2008 Posted January 19, 2008 ... It should still recrystallize like normal CIA.
Frozentech Posted January 19, 2008 Posted January 19, 2008 You need to get the KNO3 to crash out of solution. not slowly crystallize. The smaller the KNO3 crystals in the mix, the better the BP will burn. This is why the CIA method uses iced down alcohol dumped into the hot slurry. Between the low temp and the reduced solubility of KNO3 in the alcohol/H2O mix, much less of it will be left in the filtrate, and what is left in the solid residue will be the desired fine crystals.
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