Homemade Ball Mill

[Harold_V]

a study that i stumbled across on the web suggest that 1/2" to 5/8" balls as grinding media preform the best for... basiclly most of ball mills, regardless of their size and matter to be grinded. assuming that the mill is running on it's optimum RPM.

I suggest you research further. Large objects, such as extremely large pieces of ore, do not respond well to small balls. It is also well known that ball mills start with much larger balls, often as large as 6" in diameter, and have them replaced when they abrade to smaller sizes. It takes a given amount of energy to reduce the size of large objects efficiently----energy that simply isn't provided by small balls.

I would agree with your assessment, assuming the feed was small in the beginning--perhaps 1/8"-.

From personal experience----I ran my ball mill with balls that ranged from 3/4" up to 2" diameter, plus a percentage of old rollers, roughly 3/4" diameter and 1" long. Ore pieces larger than 3/4" were broken down by attrition only. A piece of gold bearing quartz roughly 1½" in size ran in the mill for days before it was reduced. My mill was something like 18" in diameter, and operated at the precise speed advised for the size. The feed I processed was sized 1/2"-, as I recall.

Harold

 

[samuel-a]

skippy - thank you for the info, this is really helpful.

Harold - that kind of personal expirience is rare, i couldn't agree more about large pieces of ore or extremely hard matirial. it does make sense.
what ball size would you recommand if i'm to feed the mill only with processors, flat packs and quad black IC's ?
a mix of 1/2" - 5/8" looks sufficient for that task?

anuther question, when job is done, how did you seperated the balls from the fine powder? simple screen?

thanks

 

[Harold_V]

skippy - thank you for the info, this is really helpful.

Harold - that kind of personal expirience is rare, i couldn't agree more about large pieces of ore or extremely hard matirial. it does make sense.
what ball size would you recommand if i'm to feed the mill only with processors, flat packs and quad black IC's ?
a mix of 1/2" - 5/8" looks sufficient for that task?

A gut feeling says no, it's not sufficient. The material from which they are made is very hard and tough. I'd suggest you would need at least 1" balls, and maybe larger. The shorter the distance the balls fall, the larger will be the requirement, too. I'm basing my opinion on the ball mill I built, which was about 18" in diameter. You may find that you require balls at least 2" in diameter in order to crush instead of abrade the feedstock. It's important that the balls crush----not just abrade.

anuther question, when job is done, how did you seperated the balls from the fine powder? simple screen?

if you build a batch mill, I have no clue. My ball mill was a constant feed, constant discharge, and was operated wet. Nothing large was able to escape the mill, and little that required further crushing was discharged. The discharge from my mill was transferred directly to a fine mesh stainless screen, with the small amount that didn't clear the screen simply added to the feedstock to be reprocessed. Discharge on my mill could be easily controlled by the volume of water that was added. The smaller the addition, the longer material remained in the mill before being discharged.

Harold

 

[4metals]

how did you seperated the balls from the fine powder? simple screen?

Most batch ball mills are dumped by removing the crushing door and putting on the dump door. Of course you will need to have a dust enclosure over the mill to collect the cloud of fine dust dropping from the holes in the dump door. Most enclosures have a drawer for the dust to collect in.