In spray drying of sugar-rich foods, agglomeration is typically implemented by recycling the fine material into the spray cone where wet droplets and dry particles collide. The outcomes of the collisions affect particle structure and therefore product properties such as flowability and reconstitution properties. This study investigates these collision outcomes by introducing a dry marker powder stream (limestone) into the atomised feed solution (maltodextrin) in both single-stage and multi-stage setup of a pilot plant spray dryer. Results showed that for the multi-stage setup, limestone agglomerated with maltodextrin and agglomerates' size decreased with increased limestone addition rate. The limestone was distributed over the whole range of the agglomerates' size distribution, but <20% (w/w) of the total limestone in the powder were located on the agglomerates' surface. The conducted study therefore demonstrated that the nozzle zone agglomeration in spray dryers is predominantly characterised by a particle-drop coalescence. (C) 2020 Elsevier B.V. All rights reserved.