Q&A

Difference between calcined kaolin and washed kaolin

time:2021/5/19 10:04:51    Views:

Kaolin is a clay composed mainly of kaolinite. After thorough weathering, feldspar produces kaolin, quartz and soluble salts. And then drift with rain and rivers to another place and pile up again, when the quartz and soluble salts have separated, you can get kaolin.


Kaolin is a kind of quality stone, kaolin clay mineral composition with small iron composition. Kaolin is composed of Alumosilicate Hydrates (Al2O3 2SiO2 2H2O) except for some mineral substances (Nacrite, Dicrite, Haloisite). Pure kaolin has high whiteness, soft quality, easy to slack suspended in water, excellent plasticity and high adhesion, excellent electrical insulation function; It has excellent acid resistance, low cation exchange capacity, good fire resistance and other physical and chemical properties. As a result, kaolin has become a necessary material for dozens of work, such as papermaking, ceramics, chemical industry, medicine and national defense.


So, what is the difference between calcined and washed kaolin?


First of all, calcined kaolin is calcined, and the crystal form and original soil have been changed; But washed kaolin is only physical treatment, will not change the nature of the original soil.


Secondly, the whiteness of kaolin varies greatly. Generally, the whiteness of kaolin will increase after light burning, while the whiteness of kaolin will not increase significantly after washing.


Third, different uses. According to different calcination temperature, kaolin can be used as additive and refractory aggregate for papermaking. Washed kaolin is generally used as papermaking filler. And, calcined kaolin now mainly refers to hard kaolin (coal series kaolin), the original soil has no bonding, can not be directly used as papermaking or refractory materials, need to be calcined in the future use; The original soil of washed kaolin has the bonding property and can be directly used as a refractory binder or papermaking filler. As a paper filler, the whiteness of calcined kaolin is much better, and the cost is also relatively high.


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