It is well known that kaolinite platelets readily aggregate into ‘stacks’, having face-to-face contact. The traditional view of kaolin has been that the platelet faces are negatively charged and the edges are positively charged in an acidic environment, but that some attraction between faces may exist at some close range of approach. Particle-scale simulations in this paper show that this is insufficient to explain aggregation during sedimentation. Recently it has been established that the silica and alumina faces of kaolinite platelets have opposite charges in acidic conditions, and taking these findings into account, discrete element simulations are presented which replicate and explain the face-to-face aggregation that occurs during sedimentation. The results demonstrate the importance of correctly modelling the interactions between the various surfaces of individual platelets in any particle-based model. Display omitted •Using Discrete Element Method to model kaolinite platelets.•Each platelet has 3 distinct surfaces: silica face, alumina face, edge.•Different interactions used between different surfaces.•Using multifaceted interactions controls ability to aggregate/flocculate.