The Sonic Pulverizer uses sound waves matched to the sonic resonance of inert material. The sound waves  pulverize inert material while still mixed in with dirt and other particles. The purpose is to pulverize glass and inert material making a fine consistent mixture. When the material is reduced down to a sand it makes it very easy to get out unwanted material. The devise does not get rid of the hard materials it only reduces them through the use of sounds waves. The machine is not a hammer mill or a shredder, it is the Sonic Pulverizer. The material has little to no contact with the disks, all the material reduction is done by the use of the Sonic resonance.