One of the problems encountered during the separation of suspensions which have various physical and chemical properties in High Gradient Magnetic Separators (HGMS) is the difference of their rheological properties. In the theory and practice of high gradient magnetic separation, the results obtained by the investigation of this problem are seldom and not enough. On the other hand, rheological properties of suspensions used in separation processes affect the efficiency of magnetic separation. Therefore, in order to get automation, improve the control of separation processes and determine the technological and economical parameters of the magnetic separators, it is necessary to take into consideration the rheological properties of the separated mediums. In this paper, by considering the rheological properties of suspensions, the investigation of the trajectory modelling of the particles in the magnetic separators has been presented. Ferromagnetic wires were used as matrix elements. In order to calculate the efficiency of the separator, analytical expressions were obtained by means of the fact that magnetic particles are collected on a magnetised wire. An integral expression of overall separator efficiency was determined by explaining the movement of a particle on a single magnetised wire. The obtained results have been illustrated by using appropriate graphics.