14. Drying Property of Kaolin

14. Drying Property of Kaolin

Drying performance refers to the performance of kaolin clay in the drying process. It includes drying shrinkage, drying strength and drying sensitivity.

Drying shrinkage refers to the shrinkage of kaolin clay after dehydration. Kaolin clay is usually dehydrated and dried at temperatures ranging from 40 to 60 degrees Celsius to no more than 110 degrees Celsius. The length and volume of the sample will shrink due to the water discharge and the shortening of particle distance. Drying shrinkage is expressed by the percentage of length and volume change of kaolin clay after drying to constant weight. The drying line shrinkage of kaolin is generally 3-10%. The finer the particle size, the larger the specific surface area, the better the plasticity, and the larger the drying shrinkage. The shrinkage of the same type of kaolin is different due to the different mixing water. The shrinkage of the same type of kaolin is larger than that of the others. In the ceramic process, the drying shrinkage is too large, and the green body is prone to deformation or cracking.

Drying strength refers to the flexural strength of mud after drying to constant weight.

Drying sensitivity refers to the degree of difficulty that the tendency of deformation and cracking may occur when the green body is dried. It is sensitive and easy to deform and crack during drying. Generally, kaolin with high drying sensitivity (drying sensitivity coefficient K > 2) is easy to form defects, while low (drying sensitivity coefficient K < 1) is safer in drying.