A method for relating operating variables and dewatering parameters of Thunes disc filters in the LKAB pelletizing plant at Malmberget in Sweden, via empirical mathematical models is described. Near orthogonal experimental design was used, where all independentvariables were allowed to span over their domain of variation and pseudo-randomly distributed among the experiments. The dewatering parameters are dependent on many variables and instead of using a traditional mechanistic model, an empirical model based on multivariate data analysis was chosen. The way of expressing the relation is by regression coefficients obtained from partial least square regression (PLS). Two empirical models were generated. The models were validated using an extra set of 56 experiments. The dewatering parameters were related to the design variables with few experiments, and user-friendly response surface methodology was used to determine the optimal conditions.