Ball mills are used in chemistry and in industry to grind hard solids to a very fine powder. They are very similar to rock tumblers. Basically, the idea is to rotate a container filled with heavy metal balls that crush the substance that you want to grind. Ball mills can be used to grind ceramic material, crystalline compounds, and even some metals.
Pulverized materials react much faster due to their higher surface area. There are several different substances that I will use to crush with my ball mill. These include but are not limited to:
This is the grinding media that my ball mill currently uses. Most of them are 3/8" steel balls sold as sling shot aumminition. The other spheres are random steel ball bearings and the ellipsoids are various lead fishing weights. Both lead and steel work great, but steels sparks so it can not be used if the mixture could possibly ignite.
Here is a schematic of how the ball mill was built. The wooden dowel that goals through the container actually stays in place and the container rotates around the stationary dowel.
My motor runs at 1725 rpm and I attached a 1-3/4" (diameter) pulley to it. This pulley turns a belt which in turn rotates a 7.5" pulley. This corresponds to a reduction ratio of 1:7.5/1.75 or 1:4.25. This means that my larger pulley runs 4.25 times slower than the motor or at about 400 rpm. The axle that the larger pulley rotates has a diameter of 3/4" (including the rubber hose) and it rotates the 3.5" container. This additional reduction of 1:3.5/0.75 or 1:4.67 means that the container should theoretically rotate at 400/4.67 rpm or about 85 rpm. I measured a speed of 80 rpm- the slightly lower speed due to frictional losses.
Oil everything up and it's good to go!
It's unsurprisingly loud! Hence I keep it in a isolated room during operation.