Ball Mill Safety Discussion Part 2

June 8, 2016

If you intend to make black powder with your ball mill, I recommend against high-alumina media for a couple of reasons:

1) There's a nagging suspicion that it sparks -- this may be due to its EXTREME hardness, which causes impacts of very tiny area, and therefore of immense forces (per square area). This might be what has ignited powder before with high-alumina ceramics, rather than actual 'sparking'.

2) Partly because of the tiny surface area of impacts mentioned above, and partly due to its low mass, alumina media is not very effective at milling black powder efficiently. Lead is often the preferred media, although a lot of folks are now using 300-series stainless steel.

Get a 'real' ball mill. Rock tumblers usually have to be re-engineered to operate efficiently as ball mills.

LLoyd

Alumina also has microscopic pours which trap material very well... Though the amount is minimal, metals can get trapped in there and cause issues. I hadn't had issues withmy media but my drum isn't gigantic either. As long as your drum isn't too big the hardness won't be an issue.

Alumina media comes in several sizes. I use 1/2" rounded cubes. My mill actually reduces material with alumina faster than lead. + no less contamination and higher media durability. If you find the right source cheaper as well. I got mine 20# for 40$

My drum uses 18# and used the same media for 6 years now with little signs of wear.

Certain rock tumblers will more than suffice, the main modification needed would probably be the rolling speed. I have an 8" diameter drum rotating at about 60 rpm off a 1/3 house motor. Works like a dream. Those small mods may prove to be cheaper than buying an actual mill.

You can easily build your own, but a proper drum will probably be the most expensive part.

I agree with you on lead being the first choice. If one were to go with a ceramic material, do you have any other preferences or insight? The reasoning behind high alumina ceramics I've always heard, including from another well known proximate pyrotechnic manufacturer, was that high alumina by definition is low silica. Silica is a known piezoelectric material. I am aware that piezoelectric sparks tend to be rather low temperature. Then again there doesn't necessarily need to be a spark for ignition via impact.

Hmmm... somehow my response to Crossout was lost! I told him, "Sorry... Never mind.".

I'll strengthen it: He doesn't know a thing about milling (except what he's "gotten away with"), and is going to hurt himself or someone else if he doesn't pay attention.

Ok -- Fully Vented now. I feel so much better! (I wonder if he bought my book on ball milling? Nahhh.... probably not! <G>)

I won't use anything but non-sparking metals on BP. PERIOD. I love alumina media for its longevity and cost, but I use it ONLY on single chemicals, or non-explosive mixtures. I never mill BP with it, with glass, or with non-alumina (silica-based) ceramics (which are _essentially_ glass).

LLoyd

I deleted it. Sorry, based on the contents I thought it was a post made in error not an actual response to CrossOut.

<G> "Kinda Cryptic", no? <G>

Anyway... Ball milling should be safe (to people... safety to hardware is your choice). If you MUST use media suspect of sparking or causing impact ignitions, then do so in a FULL BUNKER, designed to contain every scrap of what leaves when the jar finally explodes.

I wrote an AFN article about the explosion of a mill jar. (Done deliberately, CrossCut, in order to evaluate the dangers.)

Lloyd

I read that article. The actual explosion picture was a tad bigger than I would have thought would happen. I haven't run my rock tumbler in the garage since. Strictly outback with lead sinker weights and 2 rubber HF cans keeps me safe.

Good for you! Never run a ball mill with an explosive mixture in it (regardless of media) in any structure you don't want damaged! <BSEG>

Lloyd

I never saw the post.. I guess you got away with murder... I've read your article and seen what I assume to be your video about the topic and intentionally blowing up a ball mill.... Ball mills can explode shocking!

Rest assure safety is always my top priority.

That said I have yet to hear of any explosion proven to be caused by alumina media. I've thrown my media against a multitude of surfaces hand have yet to witness any spark forming from the media. Yes impact injuries are a possibility buy there is no media exempt from this issue. Hence I said for my size mill this is not a concern.

The primary thing to consider is what you are milling. How sensitive is it? Can it react with existing materials? Can any accident occur with what you are doing? I'm willing to bet that the majority of mill accidents occur as a result of milling the wrong materials.

There is a reason everyone ball mills their. There is a reason the majority of amateur pyros use this method with great success and few accidents of any.

I believe it is important that the noobie understand the risks, dangers, and challenges.

I do not believe there is reason to sow fear in them because of some urban myths or unconfirmed observations. If our odds such a concern go test it. But don't go spreading the concern based only on opinion

I can guarantee that my media is safe for my mill and my applications. Of you wish to prove me wrong please do the experimentation your self and show me the data.

June 8, 2016

As for the type of alumina media I can't guarantee a specific type. Especially if you are getting your media used. Few companies will divulge the composition of the media or even know when buying it used... That said do some testing! Go out in the dark and use a sling shot to impact it against different surfaces and the media its self. Look for a spark.

This simulates worst case sinerio and Confirmation is pretty obvious.

This simulates worst case sinerio and Confirmation is pretty obvious.
----------------------------------------------------------------------------------------

Wow! You didn't even READ my post, and now you tell others (potentially beginners) that it's unequivocally 'safe'? You say anybody who claims otherwise is just "sowing fear"?

It is NOT fear-mongering to let people know of any real or suspected reasons why a product might be unsafe in a particular application. On the other hand, it is MALICIOUS to deliberately lie about those same potentials in order to trick people into using them in an unsafe manner.

You, sir, are welcome to blow yourself up, if you choose to do so. I hope you do not. But I will gladly testify in court to have you imprisoned if anyone else becomes injured by your advice!

Try that for a "sinerio". I'm sure you'll argue that correct spelling is 'optional', and my insisting on proper spelling in a technical forum where exactitude is of first-order importance is just "criticism mongering".

Oh... that video probably wasn't mine; I've never made one. Hmmm... I don't even remember ever hearing about one.

Lloyd

Yes I actually have read your entire post. I'm still waiting on your data and results.. so far all I have heard is that you have a suspicion on the subject with no evidence to support your claim. Yet you choose to spread your suspicion without testing your self.

Your argument was: Alumina media can cause sparks. False alumina is a non sparking material. As I have said I have ran the tests and have concluded my results.

Your supporting statement was about impacts on a small area on hard surfaces..first this is not spark generation due to the media.
Second, No media is exempt from impact igntion. For the case of ball milling alumina media is no harder than stainless steel bearings. Forces created in The milling Action will be the same for all media regardless of mass (gravity). The other component will be mass which alumina has the lowest of the three. Therefore media of higher mass will present a higher risk of impact ignition. Lead will be an exception as it is a softer.

And yes it is fear mongering to present a concern without any evidence. In this case your claim is false. This is the same concept of those to believe vaccines cause autism. There's a sneaking suspicion but no evidence to support it.

As an example of my claim. glass is known to be a sparking material. Therefore it shouldn't be used. Lead, stainless steel bearings, and alumina are not sparking and may be used.

I do agree lead is probably the best option but can be much more expensive than alumina.

Tbh I'm not sure why you have so much hatred for alumina media.

CrossOut, no says that you HAVE to listen to anyone on this forum. We are simply trying our best to give advice and keep others safe. If you feel you are safe then proceed at your own risk like anybody else.

That being said, I would personally heed Lloyd's advice. That's a personal opinion.

Also, I was a bit curious about your testing methods, so I just had a couple of honest questions.

When you refer to looking for sparks with your media during high-speed impacts, what was your method of capturing an image of the side which was making the impact? Were you using a high-speed camera? Any camera at all? It would be impossible for you to see this with your own eyes as the back side of the media will obscure the line of site, making another view point a necessity.

Also, when you reference using slingshot, did you record the amount of force with a pressure plate? Did you record the force in Newtons or pounds? Grams? Just curious, as this kind of information would benefit a lot of people.
Thank you, we appreciate the information.

CrossCut... apparently you did NOT read my post -- ever. You may have 'skimmed' it for what you thought were arguments you could counter.

If you read my very FIRST point, it says that alumina is suspected of sparking, then concludes that sparking may NOT actually be the cause of the accidents that have happened. I'm going to repeat it here, and highlight salient parts so that you cannot continue to mis-report what I said:

"1) There's a nagging suspicion that it sparks -- this may be due to its EXTREME hardness, which causes impacts of very tiny area, and therefore of immense forces (per square area). This might be what has ignited powder before with high-alumina ceramics, rather than actual 'sparking'."

How could you possibly turn that into a case of my arguing that "it sparks". I NEVER said that -- and in fact, I stated explicitly that I suspect it does NOT.

All I said, and will continue to say is that, with that suspicion, one should avoid using it for milling explosive mixtures, in favor of media known not to spark. Regardless of your disdain for its potential, there have been mill ignitions while using it.

I guess it's possible you don't know what "nagging suspicion" means. Is THAT what caused you to think I expressly stated that it sparks?

You do whatever you please with your mill on your time. I have no problems with that. But don't deliberately misquote me and then claim I am wrong, and please don't teach beginners who might know less than you do about the subject. (although I can't imagine how that could be the case).

LLoyd

June 8, 2016

It's a simple fact, "Ceramic" alumina media has been in BP mill detonation, where as other, known not to spark, media hasn't. It's still generally considered a "safe enough" media, IF you can confirm that the manufacturer claims it's none-sparking. Which, point made here, not all media are. Second hand media? All bets are off. You have no idea what the specifications for the media was when it was brand new, and you have at best a vague idea what it's been used to mil since then.

In reality only the lead media in your list, is actually non-sparking. Stainless steel bearings are made from quite the range of stainless types, not all of which are even spark resistant, much less non-sparking.

More off, then on topic. lLoyd can come of as a bit of an arse every now and then (no joke) but he's generally willing to share what he can of what knowledge he has, and that is quite a bit. He can't share everything he knows, simply for business reasons, be it that he's under contract, or that he's simply making a living of specialty knowledge, and cant share those details, but the bottom line is, he simply doesn't have to make shit up and lie to you, to try and show of. What he say's is his genuine opinion. Take it at face value, and see it as advice. What ever you choose to do after receiving said advice reflects mostly on you. Everyone here suffers every time some pyro blows them self, anyone else, or property, to bits. Some of us suffer mentally, hating every accident that strikes a fellow pyro, but all of us feel the force from the authorities that try to make us stop doing pyro all together. So, trust me when saying this. Nobody here is trying to piss on you. Everyone shares whatever knowledge and information they have in an effort to make everyone as safe, and free to pursue our pyro interests as we please.

But then again, this is just me, and my opinion. You can take this at face value, and decide for your self what you want to do with it. Enjoy.
B!

"Loyd can come of as a bit of an arse every now and then (no joke)"
000

Oh! Yeah... I'll agree with that. <G>

But I don't lie to folks... there's nothing in it for me OR them!

Lloyd

Ok I'll lay this out for you from a scientific standpoint.

You have a hypothesis which you have not tested. I have tested this and find your hypothesis to be false. Alumina is a known non sparking material... Literally only you are thinking otherwise. That said please provide evidence which suggests otherwise. If you wish to argue this topic do some research your self.

Now I'll address your later statement.. Sparking is not the same as impact ignition hazard. You seem to be confused there as you keep bringing it back up.

If you read my last post I've already acknowledged the understanding of impact ignition hazard. And have already concluded that all media poses this hazard. Not just alumina as you hold to claim.

Yes we all already agree don't use media that sparks.. I am telling you alumina is within that category. If you are not referring to the actual attribute of spark producing then stop using the term.

Nagging suspicion means there is insufficient evidence to support either side of the argument.. I am proposing there is enough evidence to show the truth... If you wish to argue otherwise please provide evidence our a source.

I would like to point out you quoted your self using "nagging suspicion" with The term sparking. I'm beginning to think you aren't quite sure of what you are saying.

I would like to advise you to do more research on the topic before telling people false information. There's nothing wrong for wanting to stress safety. But at this point you are giving incorrect information whether you are willing to admit it or not.....

Tip for future post...

Oh I was under the impression alumina media had a potential a sparking hazard. Thank you for correcting me on that.

Feel free to copy and paste that.

BTW, this is not directed towards this post, but in general:

I've seen from a few sources that some stainless steel is supposed to be non-sparking?

I work with steel on a daily basis, and I never met a steel that wouldn't produce sparks. Steel is essentially iron and carbon. Stainless varieties simply contain at least 13% Chromium (as defined in the industry) which gives them their corrosion resistance. It is true that in most cases I find that stainless does produce "less" sparks. Some 'marine' grade stainless (300 series?) has much lower Carbon content meaning they will spark much less as well. But IMO any steel containing Carbon will spark if impacted hard enough to make the Carbon disassociate from the Iron. But I digress.... I simply don't feel comfortable using steel ever. My Dad was a machinist his whole life as was his Dad and his Dad, my brother works in a steel mill and my other in a machine shop until he died. I've seen a lot of steel in my life.

Again, this is not directed at this post, just a general observation of something I've seen more than once. Sorry if this is off topic.

Yeah... He _still_ didn't read anything anyone else posted... or he cannot read!

I'm done. <shrug> Beginners, please. Seek out intelligent help before committing to using something that could kill you.

Lloyd

Phoenix,
That's hardly off-topic. CrossOut has also maintained that stainless steel cannot spark. And we know it can.

Sigh! I wish this were easier. We can let the deniers just blow themselves up, but how do we defend the raw beginners?

Oh... and what the hell is "False alumina"? Yeah... I knew what he meant, but I just couldn't resist. This IS a "technical forum", after all! <G>

LLoyd

Thank you for the clarification Lloyd, I knew I read his posts, despite his disregard of our posts. Just wanted to be extra sure, as is the best practice in this particular artistic medium in which we work.

(Shrugs shoulders as well) Whadda' ya' gonna' do? Ya' can't make everyone listen.

Let's just leave him to his devices while we continue to have fun safely. To me, being extra sure of my (and others) personal safety is a lot more important than puffing my chest online.

Helloooooo to everyone present in this thread, CrossOut, Lloyd, PhoenixRising, and MrB,

While I agree this milling safety is important to discuss this topic has gone waaaaaay off topic, and gotten a little uncivil. I would like to keep this discussion going though; how about we move it to its own thread, ya?

Also, it is impossible for anyone to draw good conclusions from other side of this argument as no one has posted any sources or links to studies. As of now everything in this thread is hearsay. This is a life-critical discussion we are having, can we please treat it like one by sticking to provable facts?

Kind regards to all, Azo

Azo,
I have no ability to move this discussion. Do you? If so, please do.

There are numerous examples of mill explosions vividly depicted on the web, and most-often with good descriptions of what they were milling and with what media at the time.

I'm not inclined to go to the trouble of looking them up and posting links, when anybody can do that for themselves. I've been doing this since 1963. I've read of many milling accidents in that time. But we didn't start to actually DOCUMENT them until the "internet age".

This isn't a matter of 'opinion' in the pyrotechnic community... but perhaps you're not part of that group. Listing your bio information:
Gender:Male
Location:West Coast
Interests:Bicycling, Algorithms/Data Structures, & Cooking
NOPE... nothin' about pyro there! AND living in an area where most any pyro activity would get the law on you in seconds!

We have a number of folks who've had anything from property damage to physical injury from exploding mills using high-alumina media.

Please... DO move this discussion to a new thread, Azo.

LLoyd

June 8, 2016

Thank you! That's not _exactly_ 'moving' it, but it has the same effect. It never occurred to me to just copy and re-post EVERYTHING! <G>

(and I mean "thank you", because it wasn't appropriate for us to hijack the thread that way)

Lloyd

June 8, 2016

Here's my last input on the matter:

One case claims to have tested the matter at hand (although line of site was blocked, indicating a flawed test).

The other case states that there are known accidents where 'said media' was a factor.

If we err to the side of caution (like ANY pyro should) the answer is quite clear in this case. Sorry for hijacking the last thread.

June 8, 2016

"http://www.amateurpy...cussion-part-2/

Done.

Now please, stop the Mean Girls-esque cat fighting and name calling, I don't see how my profile has any bearing on this discussion, if I were edit it to say "Licensed Display Operator" how does that help contribute to anything here? It doesn't, and I'm not claiming to be. Anyone can edit/post what they want, and if that is nothing (like your profile Lloyd) then great, if they want to fill out every detail, then great.

I'm just asking everybody to play nice, stay relevant, and if you have an global unbending rule (from ANYONE involved) then to back it up."

------------------------

Thank you (again...). And no, I don't think you "hijacked" it. You're right...it should be here in a new thread.

But Azo, there's not any "cat fighting" going on.

One member here who has 50+ years of making fireworks, and 25+ of doing it professionally maintains that there COULD BE a danger of ignition of explosive mixtures when using high-alumina media. Even 'could' is a signal!

Another member has categorically rejected that entire possibility and is recommending that beginners with no experience use high-alumina media on explosive mixtures. And further, he attacks anyone who recommends otherwise as being irrational.

As you said in your intermediate post (I almost missed!), I think the former is the safer path (even if wrong), and the latter path (even if correct) is wrong. Saying so to beginners, knowing there's even a _possibility_ of those dangers is malicious, injurious, endangering, and STUPID!

That's not "name calling"... that's calling it "like it is"!

LLoyd

Edited June 8, 2016 by lloyd

June 8, 2016

No problem, I'm no mod so I took the same approach I take to pyro: it's about the results, as long as you can safely get the consistent result you want then do it however works for you.

I agree with PhoenixRising about erring on the side of caution, I have my own way of doing things that falls more to the Lloyd-side of the argument, but a user poll is not what's important to this back-and-forth. I, personally, would love to see some numbers or data; I have family in town but if I get some time I'll go digging scholar.google.com myself. As Lloyd mentioned he wrote a book on milling (I sadly do not own it) and an AFN article, perhaps there is some data/research there?

Thank you for staying civil ladies and gents

edit: Lloyd, I'm not claiming to have any special knowledge, and I've stated I'm not taking sides, I just want to know the truth behind both sides. I encourage anyone and everyone to err on safety, perhaps the stated practices are unsafe, I don't know, no data. Until we do, stick with what's safe, yes. There's a big difference between "here's what we advise beginners and the general public to do" and "here's what some various studies support". Perhaps they align, perhaps they don't.

edit2: Lloyd (again), sorry if I misinterpreted your comments, text is hard to convey emotions.

Edited June 8, 2016 by AzoMittle

June 8, 2016

That's a pretty sane approach, Azo, and all I _ever_ meant in all of this "gentleman's discussion" is to NOT recommend to beginners to use something suspected of being dangerous.

Once you've got some "track time", and you're willing to take risks, you do what you deem "safe enough". I've done that. Had some successes. Had some accidents, too (and got pretty severely injured in one of them...the Mg mixing case)!

LLoyd

Edited June 8, 2016 by lloyd

June 8, 2016

Lest I be misunderstood... I do NOT insist that others do things my way. There are just too many opinions in this art for that. An old homily goes, "Ask any three pyros a question, and you'll get five answers!"

But I draw the line at misguiding beginners. We risk two things if we do.

1) We risk their being injured, if we give them advice that could be dangerous.

2) we risk losing them from the art if they become discouraged. This is a dwindling craft, and we need all the folks we can muster!

CrossOut might be completely correct in his presumption that high-alumina media will not spark. (he's _completely wrong_ about various other metal media...). If he's correct, and we very narrowly confine ourselves to discussing high-alumina media, then beginners could use it safely. But they could also use non-sparking metal media safely; could they not?

And, although there are disagreements about ceramics, there are none concerning certain metals.

ALWAYS "go with the safe path" when beginning on this journey. You can take more risks later, when you understand the risks!

Lloyd

June 10, 2016

I've always wondered about using one of the aluminum bronze alloys for milling media. It is definitely non-sparking, much harder and more wear resistant than lead and though it's not as heavy as lead, it still is fairly heavy. The only problem I can foresee is the cost; it's pretty expensive.

August 2, 2016

hey guys

I don't have bronze or lead media.

just glass,and i can find steel media.

it seems glass is dangerous,so i first mill 130gr of KNO3+5gr charcoal.then mill 25gr charcoal+10 gr sulfur+20gr KNO3.

at last mix them together and mill without ball.

how about this work?

August 2, 2016

mill without ball.

how about this work?

-------------------------------

First... you are NOT "milling" if there's no media in there; you're just 'tumble mixing'. It's faster to mix with screens than with a jar mill.

Second... It won't work as well as impact-milled black powder, but will probably be just fine if you slightly adjust the amounts according to its strength.

Dave Forster has done some research that ends up with better-than-commercial powder, milling only the none-explosive combinations.

LLoyd

August 3, 2016

so if I impact them after this process,will have a good BP!

how about the steel media?

August 3, 2016

I'll have to agree with Lloyd completely on the newbie aspect. Play it safe in the beginning!!! Then as your experiance grows venture if you feel the risk is worthy or non existent. I entered this art a few years ago almost completely ignorant of most of the risks involved and value and consider any cautions I come across.

Lloyd, Dave's original experiments are with a spark resistant media not spark proof I'm not sure if any changes have been made that I may not be aware of though. For others reading the danger present with the media has been discussed and he mitigates the risks as he sees fit. I'm stating this incase there are other posts mentioning the process. It is mentioned elsewhere to some degrees.

Arw, take a look for info here on component milling. Using either of the medias you mention after component milling only screen mix them together carefully. Absolutely do not mill all components together with mentioned media, please.

http://www.creagan.net/fireworks/blackpowder.html

Unless you want to push the ragged edge with rockets you should be able to get a perfectly serviceable BP from screen mixing. Even if you have to use a tad bit more testing will answer this question. For shells if you can't get enough power for the break you want you might consider a booster. A booster may prove safer than risking limited options on media.

August 3, 2016

One thing nobody will ever hear about from me again is how to mill black powder

August 3, 2016

Sorry Dave, I should have lurked and researched a bit before I let my figures do the walking. Lloyd did mention your screen mixing process and I've noticed now other discussions here from you about it. I'm not a regular here this is about my 5th visit I think so I'm off balance a little. I'll also admit I haven't tried yet myself. Which I really should do as I do think it's fascinating what you've acomplished and shared.

When I get my modified mill back from Greg we might could do some comparison testing of batches if we can source materials from the same place if you'd be interested in that? My test stand is still out as well so that test method might be out for a while but flight times could be compared easily I would think.

Or another option for quick testing if someone wanted to test some small batches if screen mixed BP production is allowed at PGI and I make it in the next few days I could possibly supply some media for testing while I'm there out of my stash. It would be interesting to see others results on first attempts maybe. Although the most likely testing method would be granulated which has it's own vairibles thrown in it would be an interesting test. What do you think?

August 3, 2016

Sorry Dave, I should have lurked and researched a bit before I let my figures do the walking. Lloyd did mention your screen mixing process and I've noticed now other discussions here from you about it. I'm not a regular here this is about my 5th visit I think so I'm off balance a little. I'll also admit I haven't tried yet myself. Which I really should do as I do think it's fascinating what you've acomplished and shared.

When I get my modified mill back from Greg we might could do some comparison testing of batches if we can source materials from the same place if you'd be interested in that? My test stand is still out as well so that test method might be out for a while but flight times could be compared easily I would think.

Or another option for quick testing if someone wanted to test some small batches if screen mixed BP production is allowed at PGI and I make it in the next few days I could possibly supply some media for testing while I'm there out of my stash. It would be interesting to see others results on first attempts maybe. Although the most likely testing method would be granulated which has it's own vairibles thrown in it would be an interesting test. What do you think?

All types of BP are allowed to be made on site, there is an area for ball mills as well. Feel free, just communicate with Diane and Greg of your intentions and if they get short with you, it's OK, they get really busy and things ball mills etc. can get pushed back to the end of the line. The old snorts will get you set up after you get your wrist band from D&G.

August 7, 2016

I screen mix about 85% of my BP, works fine. Is not the hottest going around, but it still pops a 16" chute though a 70" body no prob. Any bigger I'd ball mill it as u do want hot powder then. ( actually then use an altimeter) As for media, NOTHING but lead. Simple as that. We just cannot add any more risk to pastime that already has an element of concern for the uneducated or unwary. I don't accept 99% sure.

That's just me though, still got all my fingers, toes & hearing.

Take care & be safe all

August 12, 2016

Speaking as a noob....i take all of the advice from everyone....why reinvent the wheel when you have access to all of this experience. Yes part of the fun is experimentation but for me not for awhile....as for ballmills.....lead all the way and then still taking plenty of precautions. Just my 2cents

August 12, 2016

I use lead for BP milling and ceramic for single chem milling like charcoal.

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Ball Mill Safety Discussion Part 2

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