Particle Formation

A Survey of IFPRI work in Formation and Assembly

              

Overview

The pre-competitive aspects of particle Formation and Assembly relate to both process understanding and product performance relations. 

  • Processing includes unit operations that are directly capable of creating new particles, assembling particles having a composite structure, further assembling particles into other superstructure forms, and even reversibly dispersing particles from larger composites back into primary particles.Unit operations within the IFPRI remit include crystallization, binder agglomeration, atomization and spray-drying, extrusion, compaction, and dispersion.IFPRI has supported several process control projects in the Formation area, including crystallization and agglomeration.Within the new structure of IFPRI, control-focus projects will be organized in the Systems area.

  • Product focus areas include the structure-property relations, where a desired performance vector may be related to a set of properties.Structure-property relations link particle characteristics (size, shape, morphology, porosity and distributions thereof) with process variables that can be used to adjust and control the same.

Summary of work by IFPRI

Particle Formation has been a focus area of IFPRI since its inception, initially focusing on processes for making particles, and more recently expanding to include particle assemblies.  Over this time, IFPRI has provided over 1 million USD in support of pre-competitive research in Formation and Assembly, much of which forms the foundational basis of current practice in selected focus areas including granulation (IFPRI projects are listed in the Appendix). 

IFPRI has an extensive record of work in granulation, including binder agglomeration and spray drying of granules.  Early work included seminal work in micro-level characterization of agglomeration with viscous binders, including modeling and experimental work elucidating the balance of inertial and viscous forces in fluidized bed agglomeration, later extended to other mechanical agglomeration systems.  Structure control is a current focus in the agglomeration area, including an exploration into the use of additive manufacturing for precise structure control.  Spray drying has included extensive work in atomization, including atomization of concentrated slurries, as well as drying kinetics in context of thermally-sensitive materials.   The current focus in spray drying is toward more fundamental understanding of single-droplet drying at elevated temperature.

Conversely, it is of industrial interest to understand dispersion of agglomerates, where dispersion may be critical to an intermediate or end-use application of the material.  Dispersion projects have focused on understanding the strength of agglomerates and their modes of rupture under various shear fields.

IFPRI’s work in aerosol formation, solvent precipitation and crystallization has several streams of focus.  One area of focus is the short-range forces and solvent effects that govern nucleation and stabilization of fine particles in suspension.  Another theme is size and shape control, using both intrinsic (e.g., gel-limited) and actively controlled processes.   A current focus area is toward molecular assembly, using templates to control nucleation.

Forming operations with high compression pressure include extrusion and die compaction.  In both cases, much focus has been given to the evolution of compacted structure as a function of process parameters and selected model materials.  The output of these projects has been significant in application of modeling to related unit operations. 

Appendix

  • Agglomeration of binder-particle systems; Tardos, Ennis and Pfeffer (City University of New York) 1990

  • Fundamental Studies of Particle Growth and Structure During Powder Synthesis; Flagan (California Institute of Technology) 1995

  • Formation of Hard Agglomerates During Drying; Smith (Univ of New Mexico) 1995

  • Effervescent Atomization of Highly Viscous, Non-Newtonian, Multiphase Fluids; Sojka (Purdue University) 1995

  • The Role of Short Range Forces on the Precipitation of Uniform Submicron Particles; Zukoski (Univ of Illinois) 1996

  • Granulation using Mechanical Agitation; York (Bradford University) 1998

  • Powder Compaction at Low and Medium Pressures: A Quasi-continuum Approach for Heterogeneous Particle Systems; Cuitino (Rutgers University) 2000

  • An integrated study of extrusion behavior or dense suspensions; Kalyon (Stevens Institute of Technology) 2001

  • Monitoring and Control of Crystal Shape in Crystallization Processes; Rawlings (University of Wisconsin) 2001

  • Quantitative Analysis of Powder-Binder Agglomeration; Litster (University of Queensland) 2003

  • Shape Control of Uniform Anatase TiO2 Nanoparticles by Gel-Sol Method; Sugimoto (Tohoku University) 2003

  • Drying and Degradation Kinetics of Heat Sensitive Products in Spray Drying; Strumillo (University of Lodz) 2003

  • Measurement and evaluation of dynamic kinetics for dispersion or consolidation of powder agglomerates; Feke (Case Western Reserve University) 2004

  • Control of droplet characteristics in liquid atomization with suspended particles; Bauckhage (University of Bremen) 2004

  • Quantitative Analysis of Structural Transformation in Extrusion Processing; Windhab (ETH, Zurich) 2007

  • Fundamental aspects of solvent effects in crystallization processes: solution chemistry and its relationship to crystal nucleation.; Davey (University of Manchester) 2008

  • Model-Based Control of Granulation Using Empirical and Theoretical Process Modeling; Doyle (University of California) 2011

  • Submicron crystallization: Building colloidal crystal dispersion from solution; Poornachary (A*STAR, Singapore / University of Singapore) 2013

  • Powder Structure Control; Kohlus (Stuttgart-Hohenheim) 2014

  • Relating compaction performance and behavior to process conditions; Zavaliangos (Drexel University) 2014

  • Tunable particles by 3D printing; Hapgood (Monash) current

  • Spray Drying of single droplets at elevated temperature; Bayly (Leeds) current