Reactive Crystallization Process Study

A project was funded by Johnson Matthey Inc. to investigate the parameters of a specific reactive crystallization process. The goal of this project was to decrease the processing time of a precious metal product, while maintaining certain product specifications. The crystallization process was examined using a reactor scaled-down from the industrial process. Based on an examination of literature, it was decided to analyze various operating parameters of the crystallization process including: impeller speed, reaction temperature, reactant feed location, and reactant addition rate. Data collection involved monitoring of pH, temperature, time, and particle size during the crystallization. Particle data was collected through the use of a Mettler-Toledo Lasentec FBRM M400, which is a laser based device. A testing procedure was standardized, and the correlation between particle size and various processing times was developed. Data from a standardized run based on the plant crystallization procedure was used to determine if the effects of changing a parameter were positive or negative. Based on the results of this project, changes to several operating parameters have been identified. Investigation was also focused on how the changes of the reaction parameters effect required product specifications.