ball mill question

[Baldor]

You are right, simple conservation of energy. The problem is reduced to how efficient is the transfer of energy from the motor to the media, and from the media to the product being milled. In a ball mill, a lot of energy goes to the angular momentum of the individual media particles, very efficiently, which in turn is converted to friction between the media and the product. In a vibratory polisher, seems the main transfer of energy from media to product is via colision, and the same from the drum to the media.

[WillowPineAndBoom]

http://www.pyrobin.com/files/Speed_Calculations.jpg

can i ask a question on that? Which one is correct the optimal or the critical rpm's to set up? Please reply thanks a lot!

[Mumbles]

The optimal RPM is what you want to use. The critical speed or RPM is when the balls start to stick to the walls of the jar. You ideally want a good cascade of media.

[Fulmen]

Correct. Just to elaborate a bit:

The critical speed is the point where the balls will stick to the inside wall due to centrifugal effects. It's used as a point of origin as it's a very precise physical effect. The optimum speed is much harder to determine, it depends on the type of mill, media, charge, phase of the moon and so on. For BP using lead ball media it should be appr 65%, but don't panic if you're a few percent off.

[SeaMonkey]

I've wondered about using the vibratory "tumbler" also and have been

looking for some evidence that it may work. I've got two ball mills that

are of the conventional variety which are just fine, but wondered if there

might be an effective alternative which may have some advantage.

 

Then I happened to find a video on youtube on the Kitchen Chemistry

channel that answered the question. Yes, it is possible. And it seems

to work quite well.

 

In the video he puts 400 grams of mix with several packets of fishing

sinkers into his vibrator and lets it "work" over a several day period.

Then he wets the pulverized product with 91% Isopropyl Alcohol and

finally, after making the mix too wet, granulates the powder and lets

it dry. At the end of the video he tests the granulated powder twice

with open burns and it is quite impressive.

 

I got the impression while watching the video that the vibratory tumber

was much less noisy than our conventional tumblers. Maybe even a

little safer as well possibly?

 

I guess I'll just have to get one of them and try it out.

 

Or one of these if it works well.

Edited May 26, 2020 by SeaMonkey

[SeaMonkey]

If anyone here has used a Vibratory Tumbler for pulverizing Black Powder

or any other of the various chemicals used, how did it work out?

 

Any differences in milling time or effectiveness?

 

Any difference in noise level?

 

Any problems emptying product and media from the tumbler?

 

And any other aspects which were experienced, pro or con?

[BetICouldMake1]

For the same cost of the vibratory tumbler you could buy one of the HF rock tumbers to use as a ball mill. I use a vibratory tumbler for cleaning my reloading brass and I can tell you it's not quiet nor does it seal up as well as a tumbler barrel. I find it very hard to imagine a vibratory tumbler being anywhere near a ball mill in terms of efficiency, you're just not going to get the cascading media effect you get in a mill. If you are already starting with very fine materials I can see it doing a decent job of mixing, but in terms of reducing particle size a ball mill is going to win every time. Could you make it work? Maybe. But why reinvent the wheel?

[SeaMonkey]

It's just something I've long wondered about. I do have two conventional

ball mills; one of Thumblers 12 lb. hexagonals and one of the Harbor Freight

6 lb. (dual 3 lb. drums.)

 

I'll do some looking around for reviews from users who've tried the vibratory

tumblers to see what their thoughts are.

 

- - - - - - - - - -

 

I did find quite a few reviews on YouTube which were very well done and

quite informative. The vibratory tumblers are very interesting machines

and I'm quite eager to give one a try. The reviewers had suggestions

for increasing their versatility and longevity of operation. With some

simple modifications I believe they could be very useful tools for the

Amateur Pyrotechnician which conceivably could greatly accelerate the

pulverizing and incorporation of chemicals and mixes.

Edited May 30, 2020 by SeaMonkey

[BetICouldMake1]

I'm certainly not going to knock experimentation. Keep us posted with your results.

[SeaMonkey]

Among the reviews were several videos showing how to make a

Vibratory Tumbler with readily available parts and materials or

small motors salvaged from various things. One showed how

to use a 12 Volt DC computer fan as the vibrator.

 

It looks like the tumblers do not require much power at all to

get them going on a relatively small scale.

 

This motor illustrates the way that the vibrations are generated in the

Vibratory Tumbler. Although it is small it would work in a home-made

tumbler for purposes of experimentation. Larger motors can be

adapted for similar operation with a little ingenuity.

 

In the video referenced earlier where Crazy Kitchen Chemistry used a

Vibratory Tumbler to make Black Powder he used a very small quantity

of Lead Sinkers as the pulverizing media. That may be an advantage

of the vibratory pulverization process. I reckon some experiments

will provide an answer to that question.

Edited May 30, 2020 by SeaMonkey

[dlking59]

I watched the video by "Crazy Kitchen Chemistry". It looked good to me and I did notice he used a small amount of of lead sinkers. At the end the BP seemed to burn quite fast.