# My new Ball Mill



## samuel-a (Jul 3, 2010)

[youtube]http://www.youtube.com/watch?v=QZwLhylCNRk[/youtube]


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## Barren Realms 007 (Jul 3, 2010)

Great job there.


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## samuel-a (Jul 3, 2010)

i forgot to thank all the good folks in here that helped with information


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## Anonymous (Jul 3, 2010)

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]


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## samuel-a (Jul 3, 2010)

gustavus said:


> 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.
> 
> ...




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.


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## Anonymous (Jul 3, 2010)

samuel-a said:


> gustavus said:
> 
> 
> > 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.
> ...



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


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## samuel-a (Jul 3, 2010)

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


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## goldsilverpro (Jul 3, 2010)

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


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## samuel-a (Jul 4, 2010)

thanks chris, i remember this posts.

now, the question is, about this formula, is it valid on a drum with baffles or a smooth one?


when using baffles, would three, 1" baffles is ok? (in a 10" drum)


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## machiavelli976 (Jul 4, 2010)

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.


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## qst42know (Jul 4, 2010)

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?


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## Barren Realms 007 (Jul 4, 2010)

qst42know said:


> 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?



There is also another option such as tapered pullies like on a multi speed drill press.


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## samuel-a (Jul 4, 2010)

qst42know said:


> Have you considered a variable speed control to provide options?



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...


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## Barren Realms 007 (Jul 4, 2010)

samuel-a said:


> qst42know said:
> 
> 
> > Have you considered a variable speed control to provide options?
> ...



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


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## qst42know (Jul 4, 2010)

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.


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## Noxx (Jul 11, 2010)

Easier than that; put a larger pulley at the ballmill's end.


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## samuel-a (Sep 22, 2010)

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....


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## dtectr (Sep 22, 2010)

samuel-a said:


> 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....
> 
> ...


 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.


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## Chumbawamba (Sep 23, 2010)

samuel-a said:


> qst42know said:
> 
> 
> > Have you considered a variable speed control to provide options?
> ...



VARIAC


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## Anonymous (Nov 30, 2010)

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:


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## Barren Realms 007 (Nov 30, 2010)

Xalebor said:


> 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:



You answered your question with you last sentance.

DUMB,DUMB,DUMB :roll:


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## Anonymous (Nov 30, 2010)

No goof ball.It's to control the landing spot of your media.If the media is landing on one side,or the other,of your material,then you simply adjust the speed so it lands directly on top of it.Im my case I have a motor that you can not run a reostat on,so I created an elevated lifter bar and shave it until the media landed on the sweet spot.


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## Barren Realms 007 (Nov 30, 2010)

mic said:


> No goof ball.It's to control the landing spot of your media.If the media is landing on one side,or the other,of your material,then you simply adjust the speed so it lands directly on top of it.Im my case I have a motor that you can not run a reostat on,so I created an elevated lifter bar and shave it until the media landed on the sweet spot.



I guess I was asleep whn I read that message....My reply was totaly wrong. I'v been looking at too many chips. :lol:  8) :roll:

Blinded by the snow....


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## Anonymous (Nov 30, 2010)

It's all good bud.


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## dtectr (Nov 30, 2010)

mic said:


> No goof ball.It's to control the landing spot of your media.If the media is landing on one side,or the other,of your material,then you simply adjust the speed so it lands directly on top of it.Im my case I have a motor that you can not run a reostat on,so I created an elevated lifter bar and shave it until the media landed on the sweet spot.


 Mic, your understanding of machine engineering completely blows me away, i'm serious. 
Or, as BR007 & i say say in our neck of the woods, "That's the diff'ernce 'tween book-larnin' & real-life larnin'!" :lol: :lol: 8)


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## Anonymous (Nov 30, 2010)

(blushing)
Thank you very much,but I owe a lot to harold and gill for my engineering skills.However I will gladly take credit for the elevated lifter bar.I am pretty sure I am the only person to have it.They may be in use,but if they are I have never seen any.


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## Barren Realms 007 (Dec 1, 2010)

dtectr said:


> mic said:
> 
> 
> > No goof ball.It's to control the landing spot of your media.If the media is landing on one side,or the other,of your material,then you simply adjust the speed so it lands directly on top of it.Im my case I have a motor that you can not run a reostat on,so I created an elevated lifter bar and shave it until the media landed on the sweet spot.
> ...



Amen to that, I will take someone with life experience over book learning anytime


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## Barren Realms 007 (Dec 1, 2010)

mic said:


> (blushing)
> Thank you very much,but I owe a lot to harold and gill for my engineering skills.However I will gladly take credit for the elevated lifter bar.I am pretty sure I am the only person to have it.They may be in use,but if they are I have never seen any.



Keep at it, you will make it to the red neck hall of fame yet.


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## dtectr (Dec 1, 2010)

mic said:


> (blushing)
> Thank you very much,but I owe a lot to harold and gill for my engineering skills.However I will gladly take credit for the elevated lifter bar.I am pretty sure I am the only person to have it.They may be in use,but if they are I have never seen any.


glad you mentioned gill - what he can engineer with a welder, motor & angle grinder (OK, there's more to it than that, but you get my point 8) ) borders on genius.


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## Anonymous (Dec 2, 2010)

mic said:


> No goof ball.It's to control the landing spot of your media.If the media is landing on one side,or the other,of your material,then you simply adjust the speed so it lands directly on top of it.Im my case I have a motor that you can not run a reostat on,so I created an elevated lifter bar and shave it until the media landed on the sweet spot.



so, as I clearly understood, the principal idea using variable speed drive at ball mill is getting speed, when balls will be rising on the top and fall down with max efficiency? Is it true?


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## Barren Realms 007 (Dec 2, 2010)

Yes


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## Anonymous (Dec 2, 2010)

Xalebor said:


> the principal idea using variable speed drive at ball mill is getting speed, when balls will be rising on the top and fall down with max efficiency? Is it true?


I am sorry xalebor but I do not fully understand the question.If you insinuating that you need more speed to get more power from the media(balls,slugs,crushing material),then no.If you are talking about the speed being adjusted so that the media falls in the correct place then yes.
If the speed is set too high,or your lifter bar is too tall,then the media will fall behind the material,defeating the purpose of the mill.Also on the other hand,if its too slow or the lifter bar is too short then the media falls in front of your material.In my case I do not have any way to control the speed of my mill unless I change my pulleys.So what I did was I found the correct combination that made my material fall just a little too far behind my material,then I shaved my lifter bar until the media fell directly on top of the material.It is important that I also remind people that size does matter.The larger the diameter tank you use,the farther the media falls before it strikes the material,hence building more kinetic energy before striking.
ALso I know a lot of you already know how my elevated lifter bar is and why I designed it that way,if anyone else wants to know,just ask and I will explain it.I think it is absolutely crucial to the efficiency of the mill.


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## Harold_V (Dec 3, 2010)

mic said:


> Xalebor said:
> 
> 
> > I think it is absolutely crucial to the efficiency of the mill.


You are far better served to calculate the proper speed and run the ball mill accordingly. That's not to suggest the lifter isn't an improvement when one isn't running at the most desirable speed. 

Harold


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## Anonymous (Dec 6, 2010)

Harold_V said:


> mic said:
> 
> 
> > Xalebor said:
> ...



in your opinion according to the experience: does the changes in input raw material (hardness, diameter etc), media (balls) wear will be so critical to cause necessity in speed regulation using frequency converter?


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## Harold_V (Dec 7, 2010)

Xalebor said:


> Harold_V said:
> 
> 
> > mic said:
> ...


I'm not convinced speed matters as to the charge. You get the very best action from the balls when they are sized properly for the size of the feed, and they ride to the apex and fall on the charge, below. Speeding up changes that sequence, and may deter proper action. Slower action is most likely to fail to lift the balls to the apex of the curve, seriously deterring grinding action. 

Ball mills that don't operate at the proper speed do a portion of their grinding by attrition----simply wearing out the material instead of hammering. When that is the case, a correspondingly high degree of wear occurs on the ball mill as well. Speed alteration would be effective only if you were running an improper speed at the outset. In the case of a lifter, that has the potential to correct for minor speed error----but you're still better off running the proper speed. It can be calculated, then established by the use of an adjustable pulley (available from Browning). Once set properly, there is no need for further adjustment. 

I do not recall the source of my information, as it's been more than 25 years since I built my ball mill, but it may have been Rose's The Metallurgy of Gold.

Harold


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## Anonymous (Dec 10, 2010)

Harold_V said:


> Ball mills that don't operate at the proper speed do a portion of their grinding by attrition----simply wearing out the material instead of hammering. When that is the case, a correspondingly high degree of wear occurs on the ball mill as well. Speed alteration would be effective only if you were running an improper speed at the outset. In the case of a lifter, that has the potential to correct for minor speed error----but you're still better off running the proper speed. It can be calculated, then established by the use of an adjustable pulley (available from Browning). Once set properly, there is no need for further adjustment.
> 
> I do not recall the source of my information, as it's been more than 25 years since I built my ball mill, but it may have been Rose's The Metallurgy of Gold.
> 
> Harold



thank You a lot for well clarifying the process...


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## artart47 (Dec 13, 2010)

I got the idea last night after having coffee with a friend who is a mechanic at the local concrete ready-mix plant! I'm going to talk to him about using one of the concrete trucks. I could put a bunch of steel balls in the mixer drum and perhaps a hundred pounds at a time of boards, cards, those pesty cable ends ect... and let it spin. I don't like the idea that a refiner is going to magneticly remove the Fe and probably some of the gold pins with it. If I was to reduce every thing to a powder and remove the Fe myself I could recover and particles that are on the iron and return it to my load. any feed back?
art


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## Barren Realms 007 (Dec 13, 2010)

artart47 said:


> I got the idea last night after having coffee with a friend who is a mechanic at the local concrete ready-mix plant! I'm going to talk to him about using one of the concrete trucks. I could put a bunch of steel balls in the mixer drum and perhaps a hundred pounds at a time of boards, cards, those pesty cable ends ect... and let it spin. I don't like the idea that a refiner is going to magneticly remove the Fe and probably some of the gold pins with it. If I was to reduce every thing to a powder and remove the Fe myself I could recover and particles that are on the iron and return it to my load. any feed back?
> art



Not a good idea. What ever concrete breaks off and mixes with your material will neutralize your acid. And you have the possability that some of you gold will be smashed and crushed into the side of the tank without the possability of recovery. You will loose more than you gain. IMHO


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## Anonymous (Dec 13, 2010)

Agreed.Not to mention the cost to operate the machine for hours and hours at a time will bite hard into your profits.


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## rusty (Dec 22, 2010)

mic curious if your recovering any silver and palladium from your milled chips.


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## Anonymous (Dec 22, 2010)

No not yet.As of right now I am only concentrating on getting the gold out.I am still fighting this tungsten problem.I just bought a new kiln this morning,and I am on the phone with barren bouncing ideas back and forth about the crucibles.He suggested trying sonitube for the outside and a plastic gallon jug for the inside,and using a soldering iron to remove the inside jug and cut the sonitube off.That should be big enough for now,until I can get some capital in and build or purchase a larger one.Barren is getting the last kiln(that I broke) and the reminants of my last ball mill.You guys either keep your fingers crossed,pray,toss some salt,or something that this works.lol.
Oh yeh,just to let you guys know...according to my wife,she is winning the lottery tomorrow,so I may be gone for a little while :mrgreen:


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## joem (Jan 2, 2011)

Thinking of my plans to build a mill in the spring and I was looking for a way to control the speed with a set of ten speed derailer gears when I can across these plans. 
They are not with derailer gears (I'll keep looking) but I think it will give some good ideas for those thinking of making a mill.
enjoy
http://www.skylighter.com/fireworks/how-to/use-a-ball-mill.asp


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## rusty (Jan 3, 2011)

joem said:


> Thinking of my plans to build a mill in the spring and I was looking for a way to control the speed with a set of ten speed derailer gears when I can across these plans.
> They are not with derailer gears (I'll keep looking) but I think it will give some good ideas for those thinking of making a mill.
> enjoy
> http://www.skylighter.com/fireworks/how-to/use-a-ball-mill.asp



Problem with using de-railer is the free wheeling ratcheting device built into the hub. But then you may have already figured this and made arrangements in your plans to compensate for this.

Please give more details on your plans.

Why not use a large diameter drum with a B belt draped over it run from a washing machine or dryer motor, you do not need a large pulley to drive the drum. The wide B Belt will have plenty of friction against the large surface area of the drum to turn it. There's no need to make this difficult.

A single B Belt should suffice, if not double up with a pair.


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## glondor (Jan 3, 2011)

What is this tungsten problem you speak of?


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## metalmickey (Apr 1, 2011)

I don't know if you might interested but there is someone on ebay that sells cheep ball mills thier members name is *hobfir* :arrow: They sell three sizes and offer a 2 years manufacturers garuntee/warrenty :!: You can use all three barrel sizes on the largest model mill. :arrow: but not the larger barrels on the smaller models :lol:


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