Edge mill

Edge runners in an oilmill

An edge mill is a mill used for crushing or grinding in which stones roll around on their edges on a level circular bed. They were developed in China in the third century and are still used today in remote villages around the world. When the millstones were replaced with iron or steel disks in the 19th century, they were known as a Chilean mill.^[1]

It is used for milling ore and as an oil mill.^[2] Horse or oxen-driven versions were used in pre-industrial revolution America as tan bark mills to shred tree bark to derive tannins for the leather industry.^[3]

1. Principle: Works on the principle of compression and shear offered to feed by heavy steel pestle.

2. Working: The feed is placed in the motor and the motor is rotated. The pestle also rotated due to friction produced between the motor and pestle. Scrapers bring the feed to the grinding zone, and the material is reduced in size and then collected and sieved.

3. Application: Brittle and crystalline substances are reduced to powder.

4. Advantage: It is a laboratory scale mill.

5. Disadvantage: It was replaced by more advanced mills.

References

1. Alban J. Lynch, Chester A. Rowland (2005), The History of Grinding, SME, pp. 78–80, ISBN 9780873352383
2. Edge mill - definition from TheFreeDictionary