A ball mill consists of a hollow cylindrical chamber (fig. 6.2) which rotates about a horizontal axis, and the chamber is partially filled with small balls made of steel, tungsten carbide, zirconia, agate, alumina, or silicon nitride having diameter generally 10 mm. the inner surface area of the chamber is lined with an abrasion-resistant material like manganese, steel, or.A true ball mill is a porcelain jar partly filled with spherical or rounded cylindrical porcelain balls. industrial versions are made of metal and have porcelain linings. small scale operations most commonly employ ball mills for grinding glazes. the suspension is poured in, a lid secured, and it is rotated on a motorized rack, sometimes for.