To suppress effectively fugitive dust emissions using water spraying systems at bulk solids handling an optimal design of these devices is necessary. The dust suppression mechanism for example at conveyor belt hand over points can be subdivided in a primary and a secondary dust minimization effect. In this case the moistening of the bulk solids is a primary dust minimization effect and the airborne dust capture is a secondary dust minimization effect. In this work the evaluation of both dust minimization effects is carried out. As a first step an experimental investigation of the total and the secondary dust suppression efficiency took place. A model of two separators which are acting in series got used to compare the measured efficiencies and to calculate the primary dust suppression efficiency. The secondary dust suppression effect showed low performance compared to the primary dust suppression efficiency. So it has to be clarified if the streaming situation and the dust concentration situation at the position where the nozzle operates can get improved. Therefore enquiries at different positions in the middle and aside a concentrated particle flow got carried out. The results provide an informative basis how water spraying systems can get improved to suppress fugitive dust emissions at bulk solids handling. (C) 2010 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.