For many industrial applications, like purification of waste water, some filtration processes and the paper recycling process, knowledge about the sedimentation and separation behaviour of fibres and particles is required. Experiments with many particles or fibres predict a great influence between them. From literature it is well known that the sedimentation behaviour is influenced by parameters like the concentration of the suspension, the physico-chemical interactions, etc. Nearly all reported experiments were performed with pure particle or pure fibre suspensions. The core difference between those suspensions is the shape of the fibres or long bodies which causes an orientation and agglomeration during the sedimentation. Hardly any experiments are reported with suspensions where particles and fibres settle together in the same suspension. To calculate such a sedimentation process with all the particle interactions one needs a suitable mathematical model, because direct numerical methods would take to much time. Therefore, in this paper we will reformulate the model of the Stokesian Dynamics Method. We will focus on the underlying assumptions and their effects and show that our simulations of some particles are in good agreement to the literature. Due to the validity of this method for spheres only, we approximate a rigid fibre as a chain of spheres and also give a comparison of this approximation. Finally we investigate the sedimentation behaviour of particle-fibre suspensions to show the influence of the density ratio between the fibres and particles and the influence of the length of the fibres on the separation behaviour.