In order for the process to be done successfully, familiarizing the material’s properties is important. The most important attribute of a material needed for size reduction equipment is its hardness in order to know what type of method to be used to attain the needed surface area. When the hardness is known, the energy used as well as the bonds of the feed can also be adjusted accordingly. Material’s hardness is usually expressed in scale using Mohs. For talcum, its hardness is set at 1 while 10 for diamond. The brittleness and the toughness of the material is also important in order to know what material are easily broken during the size reduction process.
There are other attributes that should be noted in particle size distribution such as the moisture content, the temperature sensitivity, bulk density, toxicity and the abrasiveness of the material. Another factor which should be noted is the flow property of a material.
There are four methods that are popularly used in size reduction – compressions, impact, attrition and cutting. In order for size reduction equipment to be ideal, it should have a large capacity, the power input needed is lower for every unit of product and the resulting particle size should be uniform. In size reduction process, the power needed as well as the energy is also important. During the crushing and grinding process, the cost incurred for the power used is quite high in production. This is why the factors that affect this are vital.
There are different types of size reduction equipment and classified as crushers, grinders, ultrafine grinders and cutting machines. Crushers are used when large pieces of solid particles are needed to be broken down into smaller lumps. For primary crushers, whatever materials that are extracted from the mine can be crushed into smaller units while a secondary crusher is the one responsible into further reducing the size of the material out of the primary crusher.
For an ultrafine grinder, it can only receive particles that are smaller than 6mm and the resulting size is around 1 to 5 micrometer. Cutters are used if the raw material needs to have a specific size and shape; the length is around 2 to 10 mm.
Most common types of crushers are jaw and gyratory crushers and crushing rolls. Most common grinders are hammer mills and impactors, tumbling and attrition mills and rolling compression mills. For ultrafine grinders there are hammer mills, agitated and fluid energy mills while cutters used are knife, slitters and dicers.