# Home built Ball Mill from junk yard parts



## rusty (Oct 3, 2010)

...


----------



## 4metals (Oct 4, 2010)

Nice mill, what do you do to assure the mill is emptied of all of its contents when you dump it. It seems the horizontal barrel with the bung on the end will hold up the last bit of crushed material.


----------



## joem (Oct 4, 2010)

I think the little left over can go into the next batch, but more so thanks 4metals for the tin. I expected a little piece not a full 10 inch bar. It's good for stannous and whooping bad guys. lol


----------



## 4metals (Oct 4, 2010)

It's hard for me to think leave it for the next lot, for the guy running his own material that's fine but I never ran my own stuff and the customer doesn't want to hear that part of his job went in with the next lot.


----------



## joem (Oct 4, 2010)

4metals said:


> It's hard for me to think leave it for the next lot, for the guy running his own material that's fine but I never ran my own stuff and the customer doesn't want to hear that part of his job went in with the next lot.



True enough, I was only thinking of my own items. I read about a hand held pipe mill, so If I can't get ball bearings could I use small sections of cast pipe with closed pipe ends attached?


----------



## 4metals (Oct 4, 2010)

Although anything hard and heavy will work, balls tend to be easier to clean the powders off. Failing that, there are also mills (called rod mills) that use solid bars which can freely smash about in the mill, they are usually 2/3 to 3/4 of the mill length and work well also. 

The advantage of balls is that there are more contact surfaces to crush your material. Even smaller balls mixed in with the large ball charge create more impact area.


----------



## Oz (Oct 4, 2010)

I had posted this in Gill's Hammer Mill thread, but felt it should be here as well.

Something to consider with ball and hammer mills is grounding. This is probably more important with ball mills than the hammer mills but it might be worth it to just play it safe. At issue is the build-up of static electricity in a finely dispersed dust environment. This could cause a dust explosion much like they have at feed mills occasionally. This is why they use non-sparking shovels.

A simple ground to your drum can prevent this. It would not be pretty if this were to happen in a tightly sealed steel ball mill drum.


----------



## rusty (Oct 4, 2010)

Your right Oz


----------



## goldsilverpro (Oct 4, 2010)

When I was young and curious, I put some zinc powder and silver chloride in a well sealed small ball mill along will a few small balls, just to see what would happen. Don't ask me why. When I opened the door and let in some air, the whole mass ignited will a blinding white heat. Looked like magnesium burning. Gotta be careful what you grind up.


----------



## rusty (Oct 4, 2010)

...


----------



## joem (Oct 4, 2010)

rusty said:


> goldsilverpro said:
> 
> 
> > When I was young and curious, I put some zinc powder and silver chloride in a well sealed small ball mill along will a few small balls, just to see what would happen. Don't ask me why. When I opened the door and let in some air, the whole mass ignited will a blinding white heat. Looked like magnesium burning. Gotta be careful what you grind up.
> ...



Speaking of lessons; As a kid I took an axe to a red can of spray paint to see what the rattle is inside. So I took the can to my neighbors yard, put it down between my feet and swung down and split the can in half. I guess I should have emptied the paint out first, The can exploded. I painted the side of the house, the window, the trees, and the grass red. Oh yeah and my eyes too, My mother had such a scare when she saw me screaming, my head covered in red, with an axe in my hand, trying to get through the bushes. The doctor had to scrape paint out of my eyes and I spent 3 days with patches over them. Luck has it I'm ok but to keep this thread relevant wear eye and glove protection when opening that door and don't use an axe to do it either.


----------



## glorycloud (Oct 5, 2010)

This post explains a lot to me now about you Joe. :lol:


----------



## goldenchild (Oct 5, 2010)

This forum seems to have a few Macgyverish talents. I would like to ask rusty or anyone else who has the ability to produce a fully functional ball mill what they would charge for their services. I'm thinking on a smaller scale of say 2-3 gallon drum.


----------



## rusty (Oct 5, 2010)

...


----------



## 4metals (Oct 5, 2010)

That DIY tumbler Rusty just posted is excellent for reducing 100 ounce lots of silver chloride with the caustic karo syrup method.


----------



## joem (Oct 5, 2010)

glorycloud said:


> This post explains a lot to me now about you Joe. :lol:



You know, my family wonders aboutme sometimes too
lol :shock:


----------



## Harold_V (Oct 6, 2010)

A comment about ball mills. 

Rusty talks about a bar welded inside to provide the required lift of the charge. 

It is not necessary. 

A ball mill running at the proper speed performs exactly that way, and does not benefit from the bar. 

I would encourage anyone that desires to build a ball mill to do the math and build one that runs the proper speed (I did, and I'm no mathematician). Include the bar if you can't do the math. 

Harold


----------



## rusty (Oct 6, 2010)

Harold_V said:


> A comment about ball mills.
> 
> Rusty talks about a bar welded inside to provide the required lift of the charge.
> 
> It is not necessary.


----------



## Harold_V (Oct 6, 2010)

rusty said:


> Harold_V said:
> 
> 
> > A comment about ball mills.
> ...



Interesting comment, Gill. As you alluded, my drum was, indeed, half full. I wasn't aware of the requirement, although I wanted a reasonable charge of balls for the ore I processed. I recall inserting one large piece that was VERY slow to erode. It ran in the mill for several days, and was only about 2" in size when I started. Size of the balls makes a huge difference if the material is tough and hard to fracture. Small pieces (½"-)spent very little time in the mill. 

Thanks for the enlightenment. 8) 

Harold


----------



## 4metals (Oct 6, 2010)

My experience with ball milling was heavily slanted towards jewelry sweeps and crucibles and slags. Because of this I found a lifter bar was needed. I too used a charge equal to half the volume of the mill. I also had 5 different size mills. One of the mills had no lifter bars, it performed admirably on the jewelry sweeps but they are rather easy to crush in any crusher. When it came to slags and broken up crucibles, the mill without lifter bars was woefully inadequate. It seems the lifting and dropping of the balls helped to crush the larger pieces of hard material.

Originally we used all of our mills for any crushing task based on the size of the lot, but over time we realized the mill without lifter bars would not crush hard materials as quickly as the others so it was not used for slags and crucibles.

If I were designing a mill myself, I would include a lifter bar so it would be more versatile and quicker. Larger pieces were ground up in a mill without lifters as Harold said, but it was a long process. Keep in mind that the lifter bars cause more impact on the mill itself so the walls have to be thick enough to take it. The commercially manufactured mills I used (generally Paul O Abbe) were built to take it.


----------



## Anonymous (Oct 6, 2010)

Harold_V said:


> A ball mill running at the proper speed performs exactly that way, and does not benefit from the bar.


My ball mills are made of propane tanks,with no modifications to them other than the input hole for the material.And they work perfectly.I believe my speed is around 20 rpm.I use two types of crushing media,one is a lead filled mapp gas tank.They come in two sizes,short and fat,or tall and skinny,I am using one of the tall and skinny ones,and it weighs right at 25 pounds.The other media I use is a bunch of 2" round solid steel pieces,3" in length that I call slugs.


rusty said:


> only problem with Harold's suggestion is that you'll need 1/2 or more of the drum diameter filled with balls or rods to work properly.


In my research I have found,if you have enough media in the tank,it will rotate over top of itself,creating the "lifter" effect on its own.If I use a few slugs,they tend to slide down as the tank rotates,however if I use about 20 of them,the ones on the bottom tend to push the others up and over themselves.I have never ran my tank half full,actually I can't,my setup would probably not support the weight.


rusty said:


> I'm only using 6 balls, and it only takes 2 hours to mill 20 liters of auto cat or mixed IC's into a fine powder.


I have got to try some of those balls,my mill does not work nearly that fast.
It takes about 8 hours to grind 12 pounds of ceramic cpus to powder.Maybe I need to redo my mill.


----------

