Ceramics | Viscosity Measurement of Ceramic Slurries with the Rotational Rheometer RheolabQC

The processing and transport characteristics of slurries heavily depend on their rheological properties. Knowledge about their rheological character is therefore essential, particularly when transporting a large amount of slurry. This report describes a measuring method for the rheological assessment of slurries using the rotational rheometer RheolabQC. The flow curve represents the pipe flow, the flow resistance and pressure difference.

Kaolin: Aluminum silicate hydrate Al₄ (OH)₈ [Si₄O₁₀]

Kaolin (china clay) is a potassium silicate of the mineral kaolinite. It is created by the decomposition and transformation of silicate rocks. Pure kaolin is snow-white. When mixed with quartz or ice spar it is gray-yellow (crude kaolin, kaolin sand). Kaolin which has been created by the weathering of granite and ice spar can be found in many locations around the world. It is mined using wet-chemical flotation and subsequent cleaning. The main components of kaolin are SiO₂ (35 %) and Al₂O₃ (46 % to 49 %). The pH value is approx. 5. The particle size is between 2 μm and 20 μm. The particle density is approx. 2.6 g/cm³. The sample investigated for this report was a kaolin suspension with a volume concentration of 10 % solids in water.

Test procedure

All measurements were performed with an Anton Paar RheolabQC rheometer with a sandblasted cylinder measuring system CC27 according to ISO 3219. The sandblasted surface reduces wall slipping effects. ISO 3219 describes the construction of the cylinder geometry and defines the ratio of measuring cup diameter to measuring bob diameter. This guarantees an industrial standard for shearing the sample in the measuring gap, independent of the measuring system size and manufacturer.