Mill (grinding)

For other uses see Mill (disambiguation)

A grinding mill is a tool that is designed to break a solid material into smaller pieces. There are many different types of grinding mills and many types of materials processed in them.

Small mills can be powered by hand, such as a mortar and pestle or a pepper grinder. Large grinding mills were usually powered by working animals, wind (windmill) or water (watermill) in the past. In the 2000s, most large grinding mills are powered by electricity.

Types of grinding mills

Mortar and pestle

hand mill for grinding coffee

People who need to grind a small amount of a food, such as spices or grain, for their own cooking often use a hand-powered mortar and pestle or a hand-powered grinder, such as a pepper grinder. In the 2000s, many people also used electric-powered grinding mills. These kitchen appliances have a metal blade that grinds the food into small pieces. Electric-powered grinding mills are often used for grinding nuts or coffee.

Grain mills

For thousands of years, humans have ground their grains (such as wheat or corn) into flour using grain mills powered by animals (such as oxen or horses), wind (windmills) or by running water from a stream or river (watermill). In the 2000s, most grain mills are powered by electricity.

Mechanical process

After grinding the state of the solid is changed: the grain size, and the grain shape. Also, there may be more or less crushing.

For process engineering, several things are important: increasing the surface area of the solid; making the solid have wanted grain size; and pulping the material to the desired state (squishing it).

A windmill has large sails that use the force of the wind to turn heavy stone grinding surfaces, to grind grains into flour
A watermill uses the force of running stream or river water to turn heavy stone grinding surfaces
A treadmill uses the force of a working animal to turn the stone grinding surfaces

Mill (grinding) Media

Ballmill
Principle of SAG Mill operation
A tabletop hammer mill. The input hopper is part of the front door, open in this shot to show the inner mechanism. The outlet has a mesh to determine the maximum particle size. Property of Faculty of Chemistry, Gdańsk University of Technology.
A windmill in Kuremaa, Jõgeva County, Estonia
A watermill in Kuusamo, North Ostrobothnia, Finland

Other websites

Animation of Horizontal Grinder Archived 2008-05-12 at the Wayback Machine