Kaolin is a kind of soft plastic clay mainly composed of kaolin subgroup minerals, which is mainly composed of Kaolinite minerals. In nature, Clay mineral and non Clay mineral constitute kaolin. Clay mineral are mainly kaolin minerals, followed by Chlorite group, Montmorillonite and hydrous Biotite; The key non Clay mineral are quartzite, marble, Biotite and the metal oxides of its aluminum, Nickel(II) hydroxide (diaspore and Illite), iron minerals (Hematite, Hematite, Limonite, Marcasite and Siderite), compounds (Ilmenite, Rutile, etc.), organic compounds (fiber materials, organic chemical peat and coal), etc.

The classification of kaolin, of course, the kaolin iron ore with yield rate, depends on its inducement, quality, plasticity and sandy quality (quartz, marble, Biotite and other minerals, with grain size of more than 50 μ m) The content can be divided into three industrial types: hard kaolin, soft plastic kaolin and sandy kaolin, Porcelain shaped fracture surface or shell like fracture surface, dull to crystalline luster, with vertical marks of dark gray to milky white, strength 3-4, and plasticity only after crushing and fine grinding. Soft plastic kaolin: Clay like kaolin, with a soft texture and generally strong plasticity, with a sand content of less than 50%. Sandy kaolin: It is soft and has poor plasticity, but is strong after sand removal, with a sand content of ≥ 50%.