The particle agglomeration are of great importance for a number of processes in the particle technologies. Due to the agglomeration of particles, the size and other properties of the dispersed particle phase will change. For the prediction of these changes the numerical method such as the Euler/Lagrangian approach is applicable. This work extend the application possibility of the Euler/Lagrangian approach for the prediction of the particle agglomeration in turbulent flows. The modelling of particle agglomeration encompasses the mathematical description of different separated physical phenomens, i.e. the stochastic inter-particle collision, the impact efficiency and the sticking of particle due to the attractions of the van-der-Waals forces. The process of agglomeration of microsize particles was studied experimentally in a shear layer channel. The change of particle size distribution along the channel was measured and compared with numerical results of two-dimensional Euler/Lagrangian calculations. Good aggrement for different velocity ratios in the shear layer channel was obtained by including the effect of collision efficiency into the agglomeration model. For the simulation of the particle separation in a cyclone, the 3-D Euler/Lagrangian approach including the agglomeration model has been applied. The influence of the agglomeration on the grade efficiency curve has been analyzed. The agglomeration obviously enhanced the separation efficiency for microsize particles. The agglomeration rate could be enhanced by broadening the particle size distribution or by increasing the flow rate or mass loading. Therefore, It could be shown that the addition of larger particles at the inlet enhances the separation efficiency for fine particles.