Disc mill

A disc mill is a type of crusher that can be used to grind, cut, shear, shred, fiberize, pulverize, granulate, crack, rub, curl, fluff, twist, hull, blend, or refine. It works in a similar manner to the ancient Buhrstone mill in that the feedstock is fed between opposing discs or plates. The discs may be grooved, serrated, or spiked.

History

The first disc mill was invented by Kingsland in 1856. The mill consisted of a rotating disc positioned between two stationary discs. The grinding was adjusted by axial movement of the fixed discs. The mass with a concentration of 3-4% entered under pressure through an opening located in the center of one of the fixed discs, flowed through the grinding zone between the first pair of discs in the direction from the center to the periphery, squeezed into the subsequent 30HV of grinding formed by the second pair of discs, and, moving in the direction from the periphery to the center, flowed out through an opening located at the shaft. The rotating disc was 750 mm in diameter and operated at 250 rpm, hence at a circumferential velocity of about 10 m/sec. The grinding knives were made of bronze. With a power of 22-27 kW, the mill grinds 5-8 tons per day. с. fibers.

A more advanced grinding apparatus is the Bertram disc mill. This mill is essentially similar to the previous one, but the movement of the fixed discs was accomplished in it by means of four screws driven through a worm gear. Grinding knives were made of bronze or acid-resistant steel. The inside of the mill was lined with copper or acid-resistant steel. The capacity of the mill was 24-50 tons per day.

Over the course of more than a century of evolution, a number of very different types of disc mills have been developed. Over time, grinding discs became predominantly made of sandstone and some other rocks. It was not until after World War II that they returned to making grinding discs out of metal again.

Applications

Typical applications for a single-disc mill are all three stages of the wet milling of field corn, manufacture of peanut butter, processing nut shells, ammonium nitrate, urea, producing chemical slurries and recycled paper slurries, and grinding chromium metal.

Double-disc mills are typically used for alloy powders, aluminum chips, bark, barley, borax, brake lining scrap, brass chips, sodium hydroxide, chemical salts, coconut shells, copper powder, cork, cottonseed hulls, pharmaceuticals, feathers, hops, leather, oilseed cakes, phosphates, rice, rosin, sawdust, and seeds.

Disc mills are relatively expensive to run and maintain and they consume much more power than other shredding machines, and are not used where ball mills or hammermills produce the desired results at a lower cost.

Mechanism

Substances are crushed between the edge of a thick, spinning disk and something else. Some mills cover the edge of the disk in blades to chop up incoming matter rather than crush it.