ball grinder
ball hammer
ball mill
pebble mill

After crushing, the ore passed into the ball-mill for fine grinding.

The cooled clinker ingots are crushed and ground in a ball-mill.

One of the workers is emptying ore into a small belt-driven jaw crusher; the crushed rock was fed into the ball-mill at right for grinding prior to sieving.

Another display provides tips on "Black-Powder-Coated Rice Hulls for Lift and Burst, An Easy Way, Using an Optimized Ball-Mill and Star-Roller."