A grooved plate matrix theory of a new high intensity magnetic separator is proposed. The results of the grooved plate devices yet reported, were only experimental. In the present paper, a theoretical approach is developed, in spite of the difficulties caused by the particular shape of the collectors, complicating the calculation of forces involved in the separation process. The work presented here, proposes the modeling used to study filtration efficiency in grooved matrix, for two models of fluid flow, as well as the results which were obtained. The range of validity of these models of fluid flow, applied to establish the matrix efficiency is discussed. The progressive saturation of the extraction matrix is also investigated. Good correspondence between theoretical results and experimental data is found.