In nature, minerals exist in physical and chemical combinations with each other. To separate minerals of commercial interest from the host rock both physical and chemical methods are employed. Most minerals are mined in the form of large rocks. Others like the ilmenite, rutile, zircon, leucoxene, heavy minerals or alluvial placer deposits of gold are found decimated amongst sand in beaches or in riverbeds. To access the minerals in the host rocks, they have to be crushed and even ground. When a maximum amount of the mineral of interest is separated by comminution from the parent rock, that size is usually known as the liberation size. The aim of comminution is to maximise the liberation of the mineral from the host rock. Usually the concentration of useful minerals in host rocks are low, therefore large tonnages of host rocks have to be mined to recover sufficient quantities of the useful mineral to make the operation commercially viable. The first step in the recovery process of minerals from the host rocks therefore is to reduce the size of rock by crushing and grinding.