In many engineering applications, particle-laden flows are a necessary part of the conveying process, but in other situations, they could have unintended consequences that must be avoided. As a part of the exhausting process, the induced cement-mill fan (FN-280) installed in a cement plant operates under critical conditions with the presence of high content of cement particles. Over time the dragged solid particles erode the rotating and stationary parts of the fan causing their damage. If one decides on a numerical approach to predict regions most prone to erosion and track the solid particle's trajectory within the fan domain by assuming a one-way coupling regime between the continuous and discrete solid phases, a deep insight into the flows physics within the centrifugal fan is required. With this aim, a three-dimensional numerical approach for the hole unsteady flow in a large-sized industrial centrifugal fan has been carried out in this paper. A fully resolved sliding mesh approach was employed to take into account the unsteady interaction between the impeller and the discharge volute. Based on the characteristic performance curves, the numerical results of the unsteady simulation at four operating conditions are validated with the experimental data. The comparisons reveal that the results of the unsteady simulation are in an acceptable level of agreement with the experiment, demonstrating the validity of the modelling approach adopted in this study.