Kaolin is a sub-group minerals kaolinite as the main component of the soft clay minerals and non-clay mineral types. Kaolinite minerals is less than 2μm from the small sheet or tubular form of kaolinite group minerals Al4 [Si4O10] (OH) 8. Because of its chemical composition of hydrated aluminum silicate, layered structure and particulate, with 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 a high, soft and easily dispersed suspension in the water, good plasticity and high adhesion, excellent electrical insulation properties and good acid solution, low cation exchange capacity, high refractoriness other physical and chemical properties. 
 The main physical properties of kaolin: 
 Color: white or almost white, the highest whiteness greater than 95%. 
 Hardness: the hardness of soft kaolin is generally 1-2, sometimes hard kaolin up to 3-4. 
 Plasticity: Plasticity refers to the clay crushed to reconcile with the amount of water after the shape into mud pie, in the external force can be changed from the form without the risk of cracks, out of force, when force can maintain the shape of the performance, Kaolin has a good molding, drying and sintering performance. 
 Dispersion: dispersion is the dispersion of clay minerals in suspension in the water and the nature of, or as suspension, anti-flocculation of kaolin in water, easily dispersed, suspended, can form a stable and good suspension. 
 Electrical insulation: Kaolin has a good electrical insulation properties, 200 ℃ when the resistivity is greater than 1010Ω · cm, can be used for cable fill. 
 Chemical properties: 
 Chemical stability, good acid soluble kaolin. 
 Cation exchange capacity. Cation exchange capacity of clay minerals in the PH value of 7 means the condition, clay minerals can exchange cations down the total, including the exchangeable bases and exchangeable hydrogen, in units of mmol / g, both the dry sample per 1g to exchange the cation exchange capacity is generally 0.03-0.05mmol / g. 
 Refractoriness. Kaolin chemical composition of Al2O3 and SiO2, it has excellent fire resistance, refractoriness is 1770-1790 ℃.