i think my KNO3 has absorbed a fair bit of moisture, is it still good to mill

[oldmanbeefjerky]

HI,

 

lately ive realized i dont do anything, so im going to get back into pyrotechnics and do things properly, no more improvisation and hopefully, no more failures like my last bp.

I want to mill up some BP, ive bought myself some quality willow charcoal, so it should work properly this time, however, ive noticed my KNO3 is behaving odd, its like wet sand, sort of, though it feels dry, im not sure if this is normal or no, for the particles to stick together to the extent they do, its not exactly like wet sand, but still. ive also noticed i cant really mill my powder down at all, moisture might explain this.

 

the nitrate has been exposed to very high humidity climates for a considerable amount of time and has only been stored in double bagged ziplock bags, so the possiblity is there. Of course perhaps this is just how fine potassium nitrate behaves normally i dont specifically recall it ever behaving suspiciously in the past so i dont know.

I was wondering, since this moisture would actually be preventing my mill from exploding, opposed to totally anhydrous KNO3, should i mill with it as is then dessicate, or dry it out first then mill.
im not sure if it makes a difference or not either way but if it does i want to do this properly.

Its my understanding that completely dry nitrate would be more prone to accidental ignition in the mill, but, is it? or is it still safe to mill completely anhydrous potassium nitrate, as far as safe goes when milling bp.

 

 

 

[BurritoBandito]

I'd dry it to get an accurate weight. Also, I have read several threads which state that BP is actually more prone to ignition when damp.

[jessoman]

You got the bug again after territory day mate?

 

Give it a good dry in the hot dry sun you have up there all year if not, pm me and I can give you a link for a nice dehydrator- even slow cook it. I have read somewhere that high heat affects it. But it has to be pretty high. Good slow dry would be the go so it doesn't dry strangely.

 

I also second the increase in ignition likelyhood with damp Bp- something to do with static? I'm not sure but I have read it.

[oldmanbeefjerky]

actually i havent partaken in territory day the past 2 years, i was away for both.
i think its worth investing in a dehydrator though if you think its actually safer to go super dry than not. Incidentally ive been needing a dehydrator anyway, my mint is overruling the garden and at this point its about 2-3 years worth, so i can probably kill it now, but without a dehydrator it would surely spoil in the weather conditions if i werent constantly there to make sure things go smoothely. where i am we have no humidity allot of the time, so its cold in the shade and burning in the sun, cant dry anything unless its out in the sun.

 

anywho, ide like to hear more about this moisture causing ignition.

[MrB]

I cant help with moister causing ignition, but if the stuff isn't dry, it's not going to mill well. It will just clump up. It feels weird to dry it out, just to add water to it in the process of using it, but we got to work with the physical limitations we got.

B!

[BurritoBandito]

@Oldmanbeefjerky: I actually can't find any of the threads which discuss the sensitivity of damp BP. IIRC Mumbles said that BP was found to be most sensitive at around 5 or 6% moisture. I know I have read it in at least one thread. I'm pretty sure I've seen it in two or three. Maybe someone else will remember.

[Bobosan]

BB, I think it was on fireworking.com where damp BP was discussed as being more sensitive.

[Shadowcat1969]

I've seen it discussed both on Fireworking and here. I don't remember the magic number either, 5 or 6% sounds about right though.

 

I was unsure in the first post whether or not he was asking about milling the damp vs. dry KNO3 or complete BP. Either way, I would suggest drying the KNO3 completely, as BurritoBandito said both to make sure your weight is correct and because milling even slightly damp chems is much more of a pain in the butt.

 

I'd probably suggest pre-drying your charcoal as well, if it has been exposed to the same humid conditions as the KNO3. Don't dry them at the same time in the same oven/dehydrator.

[TYRONEEZEKIEL]

You definitely need to dry your KNO3. I have the same exact problem. My KNO3 absorbs moisture and appears like wet beach sand. Just like you mentioned. I have a small rotisserie oven that I have sabotaged and turned into a chem drier. I 'cook' my KNO3 for 30 minutes, and it comes out a very dry, crumbly, and sugary powder, not the damp sand looking stuff.

 

I have tried making BP with the damp KNO3 and the dry KNO3. The dry stuff makes a world of improvement.

 

You mentioned not being able to mill your powder. There should be no reason that any of the 3 components of BP wont easily mill. Would you mind describing your ball mill?

[oldmanbeefjerky]

well what i meant was the effort was futile, it wouldnt mill on its own. it made perfectly fine BP, it was like handling flour almost, but not quite so dense. on its own however, i think the moisture causes it to clump up and ultimately maintain its initial coarse texture. so, all 3 together was ok, but the kno3 alone simply wouldnt work. i tried with both my old steel media, and my alumina media, neither worked. i only tried with the steel ball bearings in a small amount, just to see if it was perhaps the fault of the alumina somehow which it wasnt.
This was one thing about it i didnt like, that i couldnt pre-mill my kno3 to reduce the final mill time.

 

as for my mill, its pretty much the standard ball mill you get from harbor freight, the cheap looking deceptively thick sheet metal mill with the black rubber barrel with an aluminium cap, and an aluminium radiator arrangement above what i asume in an induction motor. Its modified a bit though, as its a 120v 60hz ball mill running off 120v 50hz via my 500w stepdown converter, so it gets uncomfortably hot without the aid of pc cooling fan installed in the bottom to increase airflow to compensate, which it does.

 

i eventually plan to build a new mill as soon as i can find a brushless motor that wont wear, every now and then i try bidding on some of the higher power brushless rc plane motors on ebay in hopes of winning one, or otherwise im just keeping an eye out for any other slow brushless motors.

[schroedinger]

You really need to dry first. I didn't see that discussion on fireworking but the discussion here. Also there is paper published by the ATF which discribes a study done on this topic, and it has the same answer. It foh d that bp js most sensitive and fastes burning at about 6% moisture.

[Mumbles]

Have a link or title to this paper?

[schroedinger]

Still searching for it. Hope ican find it again

[Mumbles]

I've heard and generally believe this as well. I've been trying to find the source as well. I thought it was in Davis, but I couldn't find it when I looked. My recollection is that BP is the most sensitive around 2%, but also entirely undocumented. 6% is pretty wet. Considering that most BP contains around 1-1.5% moisture on average, it may not be as big of a deal as we're making it out to be. A 1-1.5% value is in Davis, and a general approximation of other values I saw while trying to find a credible source for this claim.

[oldmanbeefjerky]

well, im definitely using this as the excuse i finally need, to go out and buy a food dehydrator.

[schroedinger]

I looked at my notes and the paper was published at the google play store, but got removed (just like their paper about military evolution and preparation of HE).Sry so i can not post the link.

[Mumbles]

Since you have your notes, you should still have some sort of title or reference though, right? At the very least a dead link stating that the file was removed, which may help to track down a copy.

[jessoman]

http://www.ebay.com.au/itm/310581371734?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

 

I know someone that uses this one. Free courier is good, considering your location.

Edited July 9, 2014 by jessoman

[oldmanbeefjerky]

looks good too, thanks.