Consideration Of Surface Chemistry Of Kaolinite To Improve Its Dewatering Characteristics

Abstract:

Kaolinite is both a blessing and a curse. As an important industrial mineral commodity, kaolinite clays are extensively used in the paper, ceramic, and paint industries. In other situations, kaolinite is a complete nuisance, for example, during recovery of bitumen from oil sand, and during sedimentation of oil sand tailings for water recovery. It is therefore the objective of this paper to investigate selected physical and surface chemical properties of kaolinite, specifically the surface charge of kaolinite particles. Surface force measurements were conducted to interrogate the basal planes of kaolinite particles (silica tetrahedral face and alumina octahedral face). These colloidal force measurements reveal that the silica tetrahedral face of kaolinite is negatively charged at pH > 4, whereas the alumina octahedral face of kaolinite is positively charged at pH < 6, and negatively charged at pH > 8. This new information was utilized to calculate the interaction energies between the different surfaces of kaolinite particles. Results indicate that the silica face–alumina face interactions are dominant for kaolinite particle aggregation at low pH and intermediate pH of 5-5.5. This explains the maximum yield stress, settling rates and aggregation behavior at pH 5-5.5.

Keywords:

Full Text:

Cite this article as: