The Viscosity Of Kaolin

Viscosity refers to a characteristic of a fluid that hinders its relative flow due to internal friction. Its magnitude (acting on 1 unit area of internal friction) is represented by viscosity, in units of Pa · s. The determination of viscosity is generally measured using a rotational viscometer, which measures the rotational speed in kaolin mud containing 70% solid content. In the production process, viscosity is of great significance. It is not only an important parameter in the ceramic industry, but also has a significant impact on the papermaking industry. According to data, when using kaolin as a coating in foreign countries, the viscosity is required to be about 0.5Pa · s for low-speed coating and less than 1.5Pa · s for high-speed coating.

Thixotropy refers to the characteristics that the slurry that has been thickened into gel and no longer flows becomes fluid after being stressed, and then gradually thickens into the original state after being static. The thickness coefficient is used to represent its size, and it is measured using an outflow viscometer and a capillary viscometer.

The viscosity and thixotropy are related to the mineral composition, particle size, and cation type in the mud. Generally, those with high content of montmorillonite, fine particles, and sodium as the main exchangeable cation have high viscosity and thickening coefficient. Therefore, in the process, methods such as adding highly plastic clay and improving fineness are commonly used to improve its viscosity and thixotropy, while methods such as increasing diluted electrolyte and water content are used to reduce it.