6 different milling technologies for powders

Grinding by impact of the particle on the tool	Grinding by moving of the tool on the particle	Impact grinding between particles
Crushing with the tool	Crushing by attrition with the tool	Shear milling with the tool

The action of fragmentation causes particle size reduction of solid materials to achieve various objectives including: improvement of storage conditions, transport, mixing, etc.

Examples of installations:
-  Grinding process line for production and packaging of icing sugar.
- Our turnkey solution PalSugarIce®: grinding unit for the manufacture of icing sugar.

Grinders are generally classified according to the size of the particles they process:

• Crushers to obtain large fragments
• Grinders for powder production
• Sprayers or micronizers for the preparation of very fine powders
• Disintegrators for breaking up fibrous materials.

Particle size reduction can be achieved through different types of fragmentation:

• Cutting: reduction of very large blocks of material from quarries or mines into pieces with dimensions greater than 100 mm
• Crushing: reduction to sizes ranging from 25 to 100 mm
• Granulation: reduction to sizes from 6.3 to 25 mm
• Grinding: reduction to sizes between 0.4 and 6.3 mm
• Spraying: production of particles smaller than 0.4 mm
• Micronization: reduction to the size of microns
• Defibration: fragmentation of fibrous materials
• Shredding: reduction by chopping flexible materials
• Cutting: sawing or shearing to obtain regular splinters

Some names of machines involved in the industrial fragmentation process: 
Jaw crushers, gyratory crushers, roller crushers, roller mills, wheel mills, disc mills, rotary impact mills (hammer mills, pin mills), Bar mills, ball mills, jet mills, super mills, micronizers...

• Reduction rate: this is the difference between the average dimensions of the particles before and after the fragmentation operation. The reduction rate varies from about 5 to 100.
   
• Hardness: it is defined in comparison to another material. A solid is harder than another if it scratches it and is not scratched by it. The commonly used hardness scale is the MOHS scale (examples: gypsum 2, fluorite 4, talc 1, diamond 10).
   
• Friability: it is represented by the ease with which a substance is broken by percussion. For example, coal and diamond are friable substances, plastics are not. Friability is not related to hardness.
   
• Moisture Content: A generally acceptable moisture content is 1-4%. Beyond that, there is a risk of formation of a pasty material.
   
• Dry or wet process: the wet process is used when the product is in a wet state or if it will be used wet. The dry process is preferred if the product is to be dried subsequently, and also to avoid agglomeration of the material.
   
• Energy consumption: The energy consumption during the grinding process is high and increases with the desired fineness. In dry grinding, the additional energy consumption can be up to 30%, but the advantage of wet grinding is lost if the product has to be dried or deagglomerated later in the process.