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Bullion.Forum
My new Ball Mill
- Thread starter samuel-a
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Barren Realms 007
In Remembrance
Great job there.
A
Anonymous
Guest
You'll have to slow the drum RPM to get an effective milling action. From the Youtube video below you can hear the media falling onto the drum.
Also if you look at the simple arrangement of sealing the door on the ball mill below. The door plate is much larger than the hole it has to cover fitted with a gasket then pulled tightly against the inside of the drum from the outside using strong backs.
To help align the door plate and strong backs, I have welded a round rod onto the outside face of the drum.
The tape you have used to seal the leaks is going to have a lot of values adhered to it, you will either have to incinerate the tape or soak in solvent to reclaim your values.
[youtube]http://www.youtube.com/watch?v=_YHHww7RJdE[/youtube]
Also if you look at the simple arrangement of sealing the door on the ball mill below. The door plate is much larger than the hole it has to cover fitted with a gasket then pulled tightly against the inside of the drum from the outside using strong backs.
To help align the door plate and strong backs, I have welded a round rod onto the outside face of the drum.
The tape you have used to seal the leaks is going to have a lot of values adhered to it, you will either have to incinerate the tape or soak in solvent to reclaim your values.
[youtube]http://www.youtube.com/watch?v=_YHHww7RJdE[/youtube]
samuel-a
Well-known member
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- Oct 7, 2009
- Messages
- 2,190
gustavus said:
thank you Gill for the comments.
i still have some finishing to do on the drum, i know.
this was just a test run with some gravel in side nothing else.
about the RPM, keep in mind that my drum is smaller then yours therefore i need more RPM, on the other hand, i know i'm to fast on the RPM. the thing is, that i can't find a reliable formula for calculating critical speed...
some formula says 91, and some says 123 etc...
once i'll find the optimum point i'll give the drum some rubber belt cover to adjust the for the desired speed.
A
Anonymous
Guest
samuel-a said:
Your wrong about the smaller drum having to turn faster, ultimately you want about 30 rpm or slower. For the hobby refiner time is of no essence so having properly designed equipment is no real issue close is good enough. Have you welded a baffle the length of the drum to catch and bring the mill balls or whatever you have used for media to the top to drop onto the chips being crushed.
I suggest that you look to youtube for rock tumblers, to get an idea of the required RPM you need, with out the baffle welded lengthwise in your ball mil all you have is a polisher. That baffle inside is what make the difference between a rock tumbler and ball mill.
On the big commercial ball mills there's a feed end and a discharge end, the heavier ore ( chips ) tend to settle out on the bottom forcing the ground up powders out the discharge so milling becomes a continuous operation.
In our case we seal the drum both ends enclosed with the balls inside do the dirty work, which is all based on gravity. I'm sure that you have been on carnival rides where gravity tends to force your body into g-forces. Your fast turning drum is going to force everything the outer walls of the drum, no longer tumbling.
If your drum is turning slow enough to have the media fall and tumble your have the RPM close enough.
If you were building a spin dryer to get the water out you have the perfect setup, you just need some holes on the outer drum for the water to escape.
Off topic but this is exactly what my next project is going to be a spin filter to extract the residual AR from processing milled up catalytic comb and bead.
Best Regards
Gill
samuel-a
Well-known member
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- Messages
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thanks for the input.
i'll dig up a shorter part of a 10" pipe and weld baffles in side.
this drum is way to large anyway.
i even have a pulley that will bring a 10" drum to around 30 RPM.
i was a little inspired by this movie:
[youtube]http://www.youtube.com/watch?v=O2-gg0C2Asw[/youtube]
(horrible music)
and by this study:
http://www.pauloabbe.com/productLines/millingEquipment/principlesofgrinding.html
i'll dig up a shorter part of a 10" pipe and weld baffles in side.
this drum is way to large anyway.
i even have a pulley that will bring a 10" drum to around 30 RPM.
i was a little inspired by this movie:
[youtube]http://www.youtube.com/watch?v=O2-gg0C2Asw[/youtube]
(horrible music)
and by this study:
http://www.pauloabbe.com/productLines/millingEquipment/principlesofgrinding.html
The speed is very important. Here's a couple of threads on this. The proper speed can be calcualted.
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=3107&p=27921&hilit=ball+mill+speed#p27921
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=47&t=5734&p=51129&hilit=ball+mill+speed#p51129
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=40&t=3107&p=27921&hilit=ball+mill+speed#p27921
http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=47&t=5734&p=51129&hilit=ball+mill+speed#p51129
machiavelli976
Well-known member
- Joined
- Mar 25, 2010
- Messages
- 263
A ball mill works due two different processes. One is the hammering effect of the balls and the other is the grinding by friction between the balls themselves and between the balls and the inner surface. any deviation from smooth cylindrical shape will reduce the friction which in most situations is quite significant. Proper speed is enough.
qst42know
Well-known member
I do like the video samuel-a. Though I must admit the first thing I did was adjust the volume control.
It depicts well the range of effects you can achieve with a ball mill by varying the RPM. From a rolling abrasive grind to a charge crushing drop at critical speed.
Have you considered a variable speed control to provide options?
It depicts well the range of effects you can achieve with a ball mill by varying the RPM. From a rolling abrasive grind to a charge crushing drop at critical speed.
Have you considered a variable speed control to provide options?
Barren Realms 007
In Remembrance
qst42know said:
There is also another option such as tapered pullies like on a multi speed drill press.
Barren Realms 007
In Remembrance
samuel-a said:qst42know said:
i have no idea how to control the speed...
the motor is marked 1380 RPM.
i think i'll stick to playing with pulley sizes...
Check and see what load the motor is pulling and you can get a device similar to a dimmer switch on a light. Size the switch acording to the load on the motor.
http://www.grainger.com/Grainger/items/5JJ60?cm_mmc=Google%20Base-_-Motors-_-Motor%20Supplies-_-5JJ60
qst42know
Well-known member
I guess I'm not a fan of German techno music. That was the back ground music wasn't it?
A variable transformer can run a motor at near any speed and can be used for a stripping cell with a bridge rectifier. Powerstat is one brand It is a very useful tool in the right amp range. Just something to consider.
A variable transformer can run a motor at near any speed and can be used for a stripping cell with a bridge rectifier. Powerstat is one brand It is a very useful tool in the right amp range. Just something to consider.
Noxx
Well-known member
Easier than that; put a larger pulley at the ballmill's end.
samuel-a
Well-known member
- Joined
- Oct 7, 2009
- Messages
- 2,190
THE KEY PART
up until now i couldn't undertand whay gill is right, all the mill did was to file the chips down a little at the time....
the solution was in front of me all of this time... i HAVE to incinerate the balck IC's first...... the incineration turns them to cookie like texture that crumbles even if your hand....
i'v incinerated a small batch, put in the mill.... after 3 minuts they were dust...
just thought i should share....
up until now i couldn't undertand whay gill is right, all the mill did was to file the chips down a little at the time....
the solution was in front of me all of this time... i HAVE to incinerate the balck IC's first...... the incineration turns them to cookie like texture that crumbles even if your hand....
i'v incinerated a small batch, put in the mill.... after 3 minuts they were dust...
just thought i should share....
dtectr
Well-known member
True - I'm working on a small-scale hand-held milling device & without incineration, I was actually abrading the plating from the exposed plated parts but not in a way that made recovery possible. The plastic just wadded up into a ball. after incineration, even partial incineration, everything became brittle & processed much simpler.samuel-a said:
Chumbawamba
Well-known member
samuel-a said:qst42know said:
i have no idea how to control the speed...
the motor is marked 1380 RPM.
i think i'll stick to playing with pulley sizes...
VARIAC
A
Anonymous
Guest
Hello, guys!
Could You pls help me with one issue?
What is the main idea of using variable speed (frequency converter) at huge ball mill?
Traditionally it's used constant speed (calculated critical speed), but recently on metal/concrete factories have been using frequency converters for the motors. I could not understand, why? May be on different stage of grinding material it's better to switch speed?? :roll:
Could You pls help me with one issue?
What is the main idea of using variable speed (frequency converter) at huge ball mill?
Traditionally it's used constant speed (calculated critical speed), but recently on metal/concrete factories have been using frequency converters for the motors. I could not understand, why? May be on different stage of grinding material it's better to switch speed?? :roll:
