Crystallization: Basic Concepts and Industrial Applications

Crystallization is a natural occurring process but also a process abundantly used in the industry. Crystallization can occur from a solution, from the melt or via deposition of material from the gas phase (desublimation). Crystals distinguish themself from liquids, gases and amorphous substances by the long-range order of its building blocks that entail the crystals to be formed of well-defined faces, and give rise to a large number of properties of the solid. Crystallization is used at some stage in nearly all process industries as a method of production, purification or recovery of solid materials. Crystallization is practiced on all scales: from the isolation of the first milligrams of a newly synthesized substance in the research laboratory to isolating products on the mulit-million tonne scale in industry. The book describes the breadth of crystallization operations, from isolation from a reaction broth to purification and finally to tailoring product properties. In the first section of the book, the basic mechanisms - nucleation, growth, attrition and agglomeration are introduced. It ensures an understanding of supersaturation, the driving force of crystallization. Furthermore, the solubility of the substance and its dependences on process conditions and the various techniques of crystallization and their possibilities and limitations are discussed. Last but not least, the first part includes an intensive treatment of polymorphism . The second part builds on the basics, exploring how crystallization processes can be developed, either batch-wise or continuous, from solution or from the melt. A discussion of the purification during crystallization serves as a link between the two sections, where practical aspects and an insight using theoretical concepts are combined. Mixing and its influence on the crystallization as well as the mutual interference of down-stream processes with the crystallization are also treated. Finally, techniques to characterize the crop are discussed. The third part of the book is dedicated to accounts of actual developments and of carried-out crystallizations. Typical pitfalls and strategies to avoid these as well as the design of robust processes are presented.

Table of Contents:
CRYSTALLIZATION: INTRODUCTION MECHANISMS OF CRYSTALLIZATION Crystal Lattice Nucleation of Crystals Growth and Growth Rate of Crystals SOLUBILITY AND SOLUTION EQUILIBRIA IN CRYSTALLIZATION Phase Equilibria and Phase Diagrams: General Issues Melt Phase Diagrams Solution Equilibria AGGLOMERATION DURING CRYSTALLIZATION Mechanisms and Kinetics of Agglomeration Parameters Influencing Agglomeration Agglomeration during Crystallization Mechanical Properties of Agglomerates POLYMORPHISM OF CRYSTALLINE SYSTEMS Introduction and Definitions Occurrence and Properties of Polymorphs and Solvates Thermodynamics of Polymorphs of Solid-State Forms Thermodynamics of Hydrates Experimental Techniques to Elucidate Thermodynamics Formation of Various Polymorphs and Solid-State Forms-Polymorph Screens Selection of Optimal Form for Development THE INFLUENCE OF ADDITIVES AND IMPURITIES ON CRYSTALLIZATION Influence of Additives and Impurities on Crystallization Influence of Impurities: Modeling Tailor-Made Additives Modeling the Influence of Solvents PURIFICATION BY CRYSTALLIZATION Introduction Mechanisms of Impurity Incorporation and Purification CHARACTERIZATION OF CRYSTALLINE PRODUCTS Introduction Characterization of Intrinsic Properties of a Solid Characterization of Particle Shape and Size Powder Flow Properties In-Process Characterization BASICS OF INDUSTRIAL CRYSTALLIZATION FROM SOLUTION Generation of Supersaturation in a Crystallizer Mass and Population Balance for Growth from Suspension Operation of a Continuous Crystallizer: Basics Operation of a Batch Crystallizer: Basics DEVELOPMENT OF BATCH CRYSTALLIZATIONS Setting Goals Crystallization of Organic Moieties Generation of Supersaturation in Batch Crystallizations Initiation of Crystallization - Nucleation Phase Seeded Batch Crystallizations Crystallization Period Scale-Up Considerations Manipulating Particle Shape CONTINUOUS CRYSTALLIZATION Concept and Design of Continuous Crystallizers Various Continuous Crystallizers Periphery Special Features of the Process Adjustment of Suspension Densities PRECIPITATION Precipitation from Solution by Mixing Two Streams Semi-Batch Precipitations Model of Mixing during Precipitation Precipitations Using Supercritical Fluids Crystal Issues Particle Size as a Function of Operating Conditions MIXING IN CRYSTALLIZATION PROCESSES Mixing in Batch and Continuous Crystallization Processes Basic Mixing Tasks - Mixing Tasks in Crystallization Impellers and Agitation Systems Power Consumption of an Impeller System [2] Blending Suspending Scale-Up of a Crystallization Process DOWNSTREAM PROCESSES Transfer of Suspension and Filter Cake Solid?Liquid Separation Drying MELT CRYSTALLIZATION Characteristics of Melt Crystallization Processes of Melt Crystallization Postcrystallization Treatments Laboratory Techniques EXAMPLES OF REALIZED CONTINUOUS CRYSTALLIZATION PROCESSES Choosing the Drain Point in Process Design Example Crop Crystallization for Organic Compounds Example Crystallization of Table Salt Results DESIGN EXAMPLES OF MELT CRYSTALLIZATION Concepts of Melt Crystallization Outlook INDEX

About the Author :
Wolfgang Beckmann is Senior Expert at Bayer Technologies. Dr. Beckmann studied Chemical Engineering and Physical Chemistry in Germany and the US. He spent one year as Postdoctoral Fellow in Marseille. Wolfgang Beckmann has spent the last 20 years working at Bayer and prior to this at Schering, developing crystallization processes for pharmaceutical compounds. He has authored several chapters in books and approximately 50 publications in reviewed journals.