Vibrating screening is still one of the main operations considering solid-solid and solid-liquid separation processes. Although it is an equipment of simple design and execution, the full description of a screening unit operation may be difficult to predict, considering that several operational variables can influence it. Therefore, the main objective of this work was to evaluate the best possible combination between the process variables screen aperture size, the volumetric concentration of solids in the feed, and the g-force (measurement of the vibration). This configuration predetermined values for moisture content of the retained material over the screen and separation efficiency regarding particle size. For this, a suspension of phosphate rock concentrate (with a particle density of 3.25 g/cm(3) and average particle size of 95 mu m) was diluted in water to perform the experiments in a pilot-scale vibrating screen. The results were analyzed statistically and correlations for each response were fit. The highest values of separation efficiency were found with the lowest values of cut-size diameter, which is desirable in terms of separation. A multi-objective optimization in the experimental range was developed, finding the optimal point for the moisture content of 17.29% and the separation efficiency of 86.88%. The effects of screen aperture size and g-force had important roles in this study. (C) 2015 Elsevier B.V. All rights reserved.