CRYSTALLIZATION AND PRECIPITATION ENGINEERING .5. SIMULATION OF THE PRECIPITATION OF SILVER BROMIDE OCTAHEDRAL CRYSTALS IN A DOUBLE-JET SEMIBATCH REACTOR

In order to simulate the precipitation of silver bromide octahedral cr ystals, a model is developed, which encompasses the main kinetic and t hermodynamic features of crystallization including primary nucleation, as well as equilibria in solution. The model is then validated during three steps (nucleation, ripening and growth) of experimental precipi tations, which are supposed to be performed under well mixed condition s. The unknown kinetic parameters of the primary nucleation process ar e fitted to experimental data through the precipitation model. These i nvestigations will contribute to a better understanding of the nucleat ion process, which is shown to be the most critical moment for the sha pe of the final crystal size distribution (CSD). Nevertheless, the dur ation of nucleation step is so short and the nuclei are so small that no quantitative results can be expected. Finally, mixing effects were observed and seemed to play a major role during the nucleation step.