The clays used in Sanitaryware body are of two types:
- Primary Clay (China Clay)
- Secondary Clay (Ball Clay)
Both belong to Kaolinite mineral group. Hence these clays predominantly contain kaolinite as the major mineral with other impurities.
Primary Clay [China Clay] :
When granite is exposed to chemical process due to weathering, the minerals like Alkali Feldspar, Quartz, Plagio Clase Feldspar and Olivine which are present in the granite go through various chemical reactions and finally Primary Clay otherwise called kaolin is formed. The clay thus formed contains lot of other impurities like undecomposed granite grains, quartz grains, feldspar grain and other organic impurities.
The aging time after the weathering process is a very important factor which decides the quantum of the impurities. The period of weathering undergone by the granite is related to the aging process. The more the time, the higher the clay content and lesser the impurites.
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