What is the difference between calcined Kaolin and washed Kaolin? After analogy, the following points are drawn:
First, calcined Kaolin is calcined, crystal and original soil has changed; The washing Kaolin is only a physical treatment and will not change the nature of the original soil.
Secondly, the whiteness difference is relatively large. Generally speaking, the brightness of kaolin increases after light burning, while washing does not significantly increase whiteness.
Third, the use is different. According to the different calcination temperature, kaolin can be used as the paper additive and the refractory material. And the washing kaolin is usually used as a papermaking filler.
Moreover, the calcined kaolin mainly refers to the hard kaolin (coal system kaolin). The original soil has no cohesiveness and can not be used directly as the raw material for paper making or refractory materials. It needs calcining after calcining. The original soil of the water washed kaolin can be bonded and can be used as a refractory binder or paper filler directly.
As a filler for paper making, the whiteness of calcined kaolin is good, and the cost is also high.
Calcining can also lead to the increase of the particle size of kaolin, although the specific surface area decreases and the adsorbability decreases, but the surface energy is reduced, the dispersity of kaolin is increased, and the structure becomes loose and the dispersity can be improved. The calcined kaolinite is usually mended as rubber and plastic after fine grinding or chemical surface modification. Strong fillers and partial replacement of white smoke.