kaolin

Industrial USES

Kaolin has become a necessary mineral raw material for dozens of industries such as papermaking, ceramics, rubber, chemical industry, coating, medicine and national defense [1].

The ceramic industry is the earliest and most applied kaolin. The general dosage is 20% ~ 30% of the formula. The role of kaolin in ceramics is to introduce Al2O3, which is conducive to the formation of mullite, improve its chemical stability and sintering strength, in the firing kaolin decomposition of mullite, forming the main frame of body strength, can prevent the deformation of products, make the firing temperature wider, but also make the body has a certain whiteness. At the same time, kaolin has certain plasticity, cohesiveness, suspension and bonding ability, endowing porcelain clay and porcelain glaze with good formability, so that the ceramic clay is conducive to rolling blank and grouting, easy to form. If used in wire, can increase the insulation, reduce its dielectric loss.

Ceramics not only have strict requirements on the plasticity, bonding, drying shrinkage, drying strength, sintering shrinkage, sintering properties, refractoriness and post-burning whiteness of kaolin, but also involve chemical properties, especially the presence of chromic elements such as iron, titanium, copper, chromium and manganese, which reduce the post-burning whiteness and produce spots.

The particle size of kaolin is generally required to be as fine as possible, so that the porcelain clay has good plasticity and drying strength. However, the particle size of ingredients should be improved for the casting process requiring fast casting, accelerating the speed of grouting and dehydration. In addition, the difference of kaolinite crystal degree in kaolin will also significantly affect the process performance of the porcelain billet. If the degree of crystallization is good, the plasticity and bonding ability will be low, the drying shrinkage will be reduced, the sintering temperature will be high, and the impurity content will also be reduced. On the contrary, its plasticity is high, drying shrinkage is large, sintering temperature is low, the corresponding impurity content is also high