Kaolin is kaolinite sub-group minerals as the main component of soft clay minerals and non-clay mineral types. Kaolinite minerals from less than 2μm small sheet or tubular kaolinite group minerals formed Al4 [Si4O10] (OH) 8. Because of its hydrous kaolin, aluminum silicate chemical composition, layered structure and particulate, have many common minerals do not have special properties. Extensive use of kaolin and its excellent physical properties are inseparable. Quality of pure white kaolin with high, soft easily suspended in water, good plasticity and high adhesion, excellent electrical insulation properties and good acid solution, very low cation exchange capacity, high refractoriness and other physical and chemical properties. 
 The main physical properties of kaolin: 
 1, Color: The color is white kaolin, or nearly white, the maximum brightness is greater than 95%. 
 2, hardness: the hardness of soft kaolin is usually 1-2, sometimes hard kaolin of 3-4. 
 3, plasticity: plasticity refers to the kaolin crushed to reconcile with the right amount of water after the shape into the clay, the external force can be changed from the form without the risk of cracks, out of force, kaolin can maintain the shape when the force performance Kaolin has a good molding, drying and sintering. 
 4, Dispersion: Dispersion is the kaolinite was suspended in water and the state of nature, or as suspension, anti-flocculation of kaolin easily dispersed in water, suspended, can form a stable good suspension. 
 5, electrical insulation: kaolin has good electrical insulation properties, 200 ℃ when the resistivity is greater than 1010Ω ? cm, can be used for cable filler. 
 Chemical properties: 
 1, chemical stability, good acid-soluble Kaolin. 
 2, the cation exchange capacity. Cation exchange capacity of kaolin is in the PH value of 7 conditions, kaolin can down the cation exchange amount, including the exchange of Exchangeable Base and hydrogen, in units of mmol / g, not only can exchange for each 1g dry sample The cation exchange capacity is generally 0.03-0.05mmol / g. 
 3, refractoriness. Kaolin chemical composition of Al2O3 and SiO2, it has excellent fire resistance, refractoriness is 1770-1790 ℃.