From Wills' Mineral Processing Technology: An Introduction to the Practical Aspects of Ore Treatment and Mineral Recovery, Seventh Edition


Grinding is the last stage in the process of comminution; in this stage the particles are reduced in size by a combination of impact and abrasion, either dry or in suspension in water. It is performed in rotating cylindrical steel vessels which contain a charge of loose crushing bodies the grinding medium which is free to move inside the mill, thus comminuting the ore particles. According to the ways by which motion is imparted to the charge, grinding mills are generally classified into two types: tumbling mills and stirred mills. In tumbling mills the mill shell is rotated and motion is imparted to the charge via the mill shell. The grinding medium may be steel rods, balls, or rock itself. Tumbling mills are typically employed in the mineral industry for coarse-grinding processes, in which particles between 5 and 250 mm are reduced in size to between 40 and 300 m. In stirred mills the mill shell with either a horizontal or a vertical orientation is stationary and motion is imparted to the charge by the movement of an internal stirrer. Fine grinding media inside the mill are agitated or rotated by a stirrer, which typically comprises a central shaft to which are attached pins or discs of various designs. Stirred mills find application in fine (15 40 m) and ultra-fine (<15 m) grinding.

All ores have an economic optimum particle size (Chapter 1), which will depend on many factors, including the extent to which the values are...

Products & Services
Grinding Mills and Pulverizers
Grinding Mills and Pulverizers are machines that grind materials into fine powders, tiny shards, shapes, or granules on a continuous basis. Often, they are used to process items that are 2 inches (5 cm) in size
Tube Mills and Pipe Mills
Tube mills and pipe mills fabricate metal tubes and pipes. Tube and pipe mills typically consist of a series of machines to form, weld, and cut metal plate or sheet to finished tube or pipe form.
Milling and Grinding Media
Milling and grinding media are designed for ball milling and the grinding down of bulk, powder or granular materials into finer powder forms or disperse pigments in a resin or coating.
End Mills
End mills are widely-used, multiple-flute cutters typically used for machining metals or plastics. They are typically mounted vertically and have two-or-more helical flutes. End mills are usually configured to cut with their ends and on their sides.
Face Mills
Face mills are primarily used for milling a face on the surface of a plate or bar. They are predominantly used to cut with the ends of the cutter rather than their sides. 

Topics of Interest

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