Kaolin and the clay mineral kaolinite are natural components of the soil and occur widely in ambient air as floating dust. Kaolinite is formed mainly by decomposition of feldspars (potassium feldspars), granite, and aluminium silicates. It is also not uncommon to find kaolin deposited together with other minerals (illite, bentonite). The process of kaolin formation is called kaolinizatio
If kaolin minerals are ground, the crystals cleave and fracture and then split into fine crystals that are considered unit crystallites and that promptly reaggregate. The assemblages of the original kaolin crystallites produced through grinding disintegrate partially into allophane or gel-like substances, These substances and crystalline particles promptly reaggregate.
With grinding, the structure of the crystalline part of the reaggregated particle slowly becomes disordered. With increase in time of grinding and in quantity of amorphous material, the reaggregated particles of disordered kaolin and amorphous substance become disk-shaped.
At a certain point in the grinding time corresponding to the maximum point on the base exchange capacity curve and the inflection point on the density curve, the particle becomes almost uniformly spherical. The structure, with continued grinding, changes finally into a structure similar to the perfectly amorphous structure of alumina-silica mixed gel and its particle size increases irregularly.
The change of structure due to dry grinding is the same in both kaolinite and halloysite, except that less grinding is required for halloysite. Therefore the effect of grinding on kaolin minerals is related to the structural perfection of the original kaolin mineral. This fact has been ascertained by the study of the all-over grinding effect of kaolin mineral.
if you need any kaolin grinding machines(like ball mill) , please contact us.