Hard clay is relatively poorly crystallised, very fine grained kaolin which is about 1 miron median particle size by sedimentation and high surface area. It provides reinforcement in rubber, resulting in hard compounds.
HomeCategory
Production
Kaolin clay is chemically hydrated aluminium silicate and structurally unmodified. Water washed kaolin is made by slurrying the raw clay and then centrifuging or hydrocyloning it to remove impurities. Chemical bleaching is done to improve the brightness of the kaolin before it is then produced into the specific grades. Kaolin is platy in structure, hydrophilic and readily water dispersible.
It is a calcium silicate mineral with the molecular formula CaSiO4. Sometimes, it is used as a buffering effect in acid solutions due to the release of calcium ion. It has moderate hardness and high dry brightness together with improved corrosion and blistering resistance.
The common name to it is Limestone. It is commonly used as a cheapening filler in various industries. Chemically, it is calcium carbonate.