The only conical ball mills on the market are those made by the . Fig. 12 shows the construction of this type of mill. ... most economical method of grinding an ore of not more than average hardness is to use a rod mill in the primary and a ball mill in the secondary stage.
The ball mill is a tumbling mill that uses steel balls as the grinding media. The length of the cylindrical shell is usually 1–1.5 times the shell diameter (Figure 8.11).The feed can be dry, with less than 3% moisture to minimize ball coating, or slurry containing 20–40% water by weight.