***Ball Mill Explosion!***

[oldspark]

Its important to remember almost all accidents can be blamed on not following safety rules or not wearing PPE.

[NightHawkInLight]

Really bummed out to hear about this. Hope your recovery is going well there BB!

[BurritoBandito]

NHIL, thank you, but don't be bummed out for me. I'm not. I am healing well and am happy things turned out as well as they did. In a few months I'll be as good as new (minus the pinky). I have a few broken bones and some lacerations. My burns are all healed up except for a small 3rd degree on my inner thiegh. My stitches have all been removed, and I am beginning to regain feeling in my right hand. Sure, it would've been better if the explosion had not occurred, but things could've been much worse. I only have myself to blame, and knowing what Dag has suffered makes my injuries seem trivial. All things considered I have it pretty good.

[oldspark]

Well BB it sounds like you have a great attitude, that will go a long way in the healing process.

[dagabu]

BB, I am good to go! No suffering here, the love from my wife and her undying support has made recovery as easy as possible. Will I return to "normal?" No, thats not possible but I am thankful for every breath.

[BurritoBandito]

Dag, you're a trooper. I was referring to debridment, skin grafts, and surgeries. What does it mean to be normal when everyone is different and our experiences are constantly shaping us? No, you're not "normal"... You're refined.

[dagabu]

Thats for darn sure! Refined through fire... Yes, there has been plenty of pain and I still have several surgeries ahead of me, maybe 1-2 every year for the foreseeable future as the scarring tightens.

[Niladmirari]

Burrito Bandito I hope you eyes are ok.

This is a very valuable experience for all of us.

I will tell this information to Russian pyrotechnics. Maybe you have saved us from disaster.

I wish you a quick recovery!!!

Edited July 29, 2014 by Niladmirari

[Richtee]

Jeeez... so sorry to hear this. My wishes for a speedy recovery....

 

I miss this hobby, but I don't miss the inherent risks involved.

[BurritoBandito]

I'm sorry everyone I lied. I was thinking I had added 2 bags of 25 marbles, but after checkling the packages they were sold in, I realized that I was wrong. They were bags of 50. Sorry for the misinformation. I know this doesn't change anything really, but for the sake of accuracy I felt the need to correct myself.

[rogeryermaw]

wow! that's about all i can muster. bandito, you are a brave man. how many people would tuck their tails and hide after such an accident? but here you are putting your story out there, risking ridicule, criticism and downright nastiness to serve the community. i thank you sir and hope your are recovering well.

 

this catastrophe brings to mind a question that has been nagging at me. i notice most people use some form of plastic mill jar be it pvc or an empty jar of whatever original purpose. many such plastics can develop a static charge. i was even thinking of making a star roller from a 5 gallon bucket but i know those can hold an amount of static charge enough to knock a man down(had a science teacher prove this to me in high school back in '89 when experiments were still allowed).

 

my question is: would it be a good idea to make some sort of grounded brush that could ride along the outer circumference of the barrel to dissipate any potentially dangerous static buildup? anyone have experience with this concept?

[MrB]

I'm sorry everyone I lied. I was thinking I had added 2 bags of 25 marbles, but after checkling the packages they were sold in, I realized that I was wrong. They were bags of 50. Sorry for the misinformation. I know this doesn't change anything really, but for the sake of accuracy I felt the need to correct myself.

This makes everything different. Now we have to go back, edit all our posts, and tell you your an ass as we go along.

Sorry, thats my poor humor showing, i know.

Nothing really changed as you said.

 

my question is: would it be a good idea to make some sort of grounded brush that could ride along the outer circumference of the barrel to dissipate any potentially dangerous static buildup? anyone have experience with this concept?

Sure. It could be a great idea. For a machine the create lightning bolts with. Read about Van de Graaff generators.

Circumstances have to be "just right" for that to happen, but the risk seams greater then the reward.

B!

[rogeryermaw]

 

Sure. It could be a great idea. For a machine the create lightning bolts with. Read about Van de Graaff generators.

Circumstances have to be "just right" for that to happen, but the risk seams greater then the reward.

B!

 

actually, the van de graaff generator was what the teacher used to build the static charge on the bucket that he tricked me with. with the generator, it arcs to the surface of the globe with a grounded rod so if you were to ground the globe, then static should not accumulate. in the mill, if the barrel could be grounded, it may help to mitigate some causes of accidents. as an amateur chemist, pyro is very near and dear to me and if it could stop one injury, i want to investigate it. my first hurdle will be to research how to measure the negative potential of a plastic surface and to guage which plastics are the worst offenders.

[MrB]

If you end up getting it wrong, then the PVC jar will be the transport mesh that would be transferring the charge to "what ever" would hold it. Most likely a part of the mill that isn't properly grounded, due to the wood box it stands on, or in... I'm just saying you can get this quite wrong, and end up making things a lot worse rather then making things better.

If static buildup is a concern, use anti-static spray before opening the jar. Or paint it with a conductive paint. Personally i think your looking at the wrong part of the process to try and make "safer". Wear your PPE.

B!

[Niladmirari]

wow! that's about all i can muster. bandito, you are a brave man. how many people would tuck their tails and hide after such an accident? but here you are putting your story out there, risking ridicule, criticism and downright nastiness to serve the community. i thank you sir and hope your are recovering well.

 

this catastrophe brings to mind a question that has been nagging at me. i notice most people use some form of plastic mill jar be it pvc or an empty jar of whatever original purpose. many such plastics can develop a static charge. i was even thinking of making a star roller from a 5 gallon bucket but i know those can hold an amount of static charge enough to knock a man down(had a science teacher prove this to me in high school back in '89 when experiments were still allowed).

 

my question is: would it be a good idea to make some sort of grounded brush that could ride along the outer circumference of the barrel to dissipate any potentially dangerous static buildup? anyone have experience with this concept?

If the composition is wet, it will not be static. Mix composition only in the wet state. 3% water or another solvent.

Edited July 31, 2014 by Niladmirari

[dagabu]

If the composition is wet, it will not be static. Mix composition only in the wet state. 3% water or another solvent.

 

You cant ball mill a wet comp, it will immediately clump, the chems must be dry.

[pyropro]

bottom line is most of you who insist on this as a hobby really shouldnt.Its not like other hobbies.Most if taken personality probes would find you dont fit.BB your one lucky man.

[BurritoBandito]

The other issue with wet milling BP is that the KNO3 will recrystalize out as it dries. Pyropro, I am extremely lucky.

[MrB]

You cant ball mill a wet comp, it will immediately clump, the chems must be dry.

Is this entirely true? We know a trace of water makes it clump, and a couple of % wouldn't make a difference, but lets play with the idea that we want to wetmill, and have loads of time on our hands... Could we use a couple of 100% water, mill, and dry it? To some (large?) extent BB is right, KNO3 will fall out of solution, and form crystals as the water evaporates, so we would end up with BP in form of finely powered nitrated charcoal, and sulfur, with potassium nitrate crystals around it all. I don't think it would make for great BP, but it could work for charcoal stars? If your pressing and corning, could it do for workable lift?

 

There is of course the alternative to use something other then water to wet mill. How about acetone? KNO3 has at best a theoretical ability to dissolve in acetone, and while acetone fill burn, having BP soaked in it should slow down the reaction-speed of the BP to something far less violent then an explosion. Add a knife's edge of KNO3 to the first batch, and then just collect it after milling. I suggest using a strainer, straining cloth, or pressing it to pucks over a collection cup, and collecting it right away, simple since letting that much acetone evaporate every time will add up on the costs over time.

B!

 

Edit

BTW, i don't suggest doing this. It's more of a thoughts experiment. I'm not to sure about how the fluid motions of the acetone would affect the actual milling, but you cant fill the jar, since stuff will float, and never get milled.

/Edit

Edited July 31, 2014 by MrB

[Niladmirari]

I use 40% solution of ethanol in water. For mixing in ball mill - 2-3% (weight). I never mix the dry reagents (chemicals) in the ball mill.

Then through a sieve.

Then for pressing add more (7% total), through a sieve 1,5 mm.

 

Except flash. If you want to flash only mix through a sieve.

Edited July 31, 2014 by Niladmirari

[Shadowcat1969]

As for static building INSIDE the mill jar, Lloyd Sponenburgh showed over on Fireworking how that really isn't a possibility. At least in a way that will cause a spark to ignite the composition within a SEALED jar.

 

I believe the static we would concern ourselves with in regards to milling/jars, would be anything that WE could introduce to the closed system when we open the jar. Therefore, anti-staic spray and grouding yourself while touching the CLOSED jar to equalize any charges before opening would be a good idea.

 

As for grounding a star roller. One of my rollers uses a plastic bowl for rolling in, but the bowl is attached using a metal bolt, which in turn is attached to a wiper motor for direct drive, which is in turn grounded. Again, as long as I don't introduce an outside charge, it should be fine.

 

Having a bowl/bucket that works more like a ball mill, on insulating rollers or using a belt and pulley system could build static and I would personally try to figure out a way to keep the static from building.

[rogeryermaw]

so if you mill outside, like we should be doing anyway, perhaps burying an isolated ground rod near your machine that could be touched prior to touching any other part of the mill would be sufficient? they're a pretty cheap safety item that anyone can get.

[dagabu]

Is this entirely true? We know a trace of water makes it clump, and a couple of % wouldn't make a difference, but lets play with the idea that we want to wetmill, and have loads of time on our hands... Could we use a couple of 100% water, mill, and dry it? To some (large?) extent BB is right, KNO3 will fall out of solution, and form crystals as the water evaporates, so we would end up with BP in form of finely powered nitrated charcoal, and sulfur, with potassium nitrate crystals around it all. I don't think it would make for great BP, but it could work for charcoal stars? If your pressing and corning, could it do for workable lift?

 

There is of course the alternative to use something other then water to wet mill. How about acetone? KNO3 has at best a theoretical ability to dissolve in acetone, and while acetone fill burn, having BP soaked in it should slow down the reaction-speed of the BP to something far less violent then an explosion. Add a knife's edge of KNO3 to the first batch, and then just collect it after milling. I suggest using a strainer, straining cloth, or pressing it to pucks over a collection cup, and collecting it right away, simple since letting that much acetone evaporate every time will add up on the costs over time.

B!

 

Edit

BTW, i don't suggest doing this. It's more of a thoughts experiment. I'm not to sure about how the fluid motions of the acetone would affect the actual milling, but you cant fill the jar, since stuff will float, and never get milled.

/Edit

 

I bet Acetone would work but it also attacks all the cheap materials that low cost ball mills are made from... It has to be a true slurry to work, adding 20% water just makes mud, it still packs against the walls. If you make BP slurry for black match, you know that the KNO3 drops out when cooled. There is no way to use water wet milling and dry it out without dropping the KNO3 out of the slurry, it just isn't possible. The over the shelf denatured alcohols and acetones have up to 10% water in them, the KNO3 drops out or crystallizes.

 

The heap rolls along the pile, floating is not a concern. I tumble rocks all the time in a liquid with grinding dust, it works very well.

[MrB]

I bet Acetone would work but it also attacks all the cheap materials that low cost ball mills are made from...

And has a nasty habit to evaporate when heated. Friction might cause that heat, increase the pressure in the jar, and pop the lid of. If i ever need to wet mill anything, i'll look in to acetone, it's cheap, available, and not THAT toxic. But it's still nasty stuff.

 

It has to be a true slurry to work, adding 20% water just makes mud, it still packs against the walls. If you make BP slurry for black match, you know that the KNO3 drops out when cooled. There is no way to use water wet milling and dry it out without dropping the KNO3 out of the slurry, it just isn't possible. The over the shelf denatured alcohols and acetones have up to 10% water in them, the KNO3 drops out or crystallizes.

I've never made black match, the water-based slurry i use is only for star rolling, at least of the top of my head.

The acetone my hardware store / painters supply carry specify the content as >99% acetone. All i really know is that it's very good at melting some plastics.

 

The heap rolls along the pile, floating is not a concern. I tumble rocks all the time in a liquid with grinding dust, it works very well.

I was just suggesting, that filling a jar to the brim would make charcoal float on top, and while the rotation should bring it down a bit, i'm not sure it would be as effective. I might have been entirely wrong, speculation at it's best. It would to some extent depend on the rotation speed as well, i suppose.

Polishing stuff with dust, can be very effective, that much i know from experience. Steel barrel, used glass sandblasting agent, and a decorative yard windmill made a very sad set of wheels look better then new.

B!

[Peret]

Couple of things that need to be said.

 

First, commercial gunpowder is always milled wet. It's done in edge mills, not ball mills, and Dag rightly says it won't work in a ball mill. After it's milled it's pressed wet, then the slabs are steam dried and broken up. Crystallization is not a problem. Large crystals can be formed if you let a jar of solution evaporate slowly, but they don't form in a paste with say 10% water. The way a crystal grows is that more nitrate is gradually deposited on the surface of the crystal from solution, and that involves having excess solution to transport it, and time to do so. There's no excess solution in damp powder and unless you dry it slowly over many days, no time either.

 

Second, my experience has been that damping powder with water improves it dramatically. I don't know why - perhaps the nitrate is transported into the microscopic pores of the charcoal - but sometimes I've saved slow powder by re-wetting it and granulating it again because I didn't make it wet enough the first time. Only water does this, not alcohol or any other solvent.

 

Third, Lloyd Sponenburgh did not "show" over on Fireworking that static can't build inside a sealed jar. He simply stated it as a fact without any facts or theory to back it up. I can show by simple experiment that static can indeed build to spark levels inside a sealed container. All that's necessary is some mechanism to separate charges by friction, and some means of keeping them apart while they accumulate. In the crudest form I'd put a van de Graff generator inside a rubber barrel. Since that would be considered cheating, I would then rearrange the parts of the VDG generator so that the charge separation took place near the center, and the charge collection took place at the barrel wall.