Mixing Unit Operations You Didn’t Learn about in School

Wednesday, June 12, 2013, 4:00pm-5:30pm CDT

Session Chair & Co-Chair:

  • David Raab
  • Kevin Joback, Molecular Knowledge Systems, Inc.

Session Description:

Many chemical products are made by combining different ingredients into a final mixture. Sometimes the process needed to combine these ingredients is simple mixing. However, many products require more complex processing such as compounding, emulsification or compaction. Some of these processes must create precise microstructures, such as specific concentration profiles, fiber orientation or particle size distribution. Often mixing agents such as dispersants, emulsifiers or binders must be included. The talks in this session will discuss the guidelines for the selection and design of such processes and show examples demonstrating their advantages and disadvantages.


Innovations in Mixing for Unmet Needs of Manufacturing and R&DKishore K. Kar, The Dow Chemical Company
Basics of Twin Screw Extrusion CompoundingDennis Kalman, Solvay
Overcoming Agitation Challenges in Cold Pearl Surfactant BlendsIan Lutz, Solvay

Innovations in Mixing for Unmet Needs of Manufacturing and R&D

Kishore K. Kar, The Dow Chemical Company

Presentation will discuss new mixing technologies and their applications in manufacturing and research. The first technology is a three bladed novel impeller specifically designed for use as a close clearance tickler impeller in a mechanically agitated slurry tank or reactor to eliminate solids heel and shorten drainage time of the viscous fluids. The second technology is a unique twisted-ribbon impeller designed for the high throughput research (HTR) applications. Small (<100 mL) lab-scale systems for rapid screening are widely employed in R&D in chemistry and biology, but commonly encounter significant mixing challenges. The new impeller design when used in the HTR vials significantly shorten the mixing time of a low viscosity fluid in a high viscosity media, and speed-up the gas drawdown from the headspace for gas-liquid mixing. Its main application is to make the laboratory reaction or dissolution processes no longer mixing rate limited; thus true reaction kinetics or the formulation efficacies can be determined. A brief discussion of the performance characteristics of these technologies will be presented using experimental and computational fluid dynamics results, and movies.

Basics of Twin Screw Extrusion Compounding

Dennis Kalman, Solvay

Twin screw extrusion compounding is used in a wide variety of processing applications, from compounded polymers for injection molding and other end uses, to polymer degassing and solvent removal, pharmaceutical hot melt extrusion, and even cereal and pet food production. This talk will focus on twin screw extrusion for compounding engineering polymers. The overall layout of a compounding production line will be presented with discussion of issues in the overall process, from feeding to extrusion to pelletizing. The key design parameters for twin screw extrusion are presented, including geometry, free volume, various screw elements, screw design, die design, pelletizing, and how to define the goals of your compounding process and select the appropriate design details. In addition, the key process parameters will be laid out and their effect on each other will be discussed. Methodology for scale-up from R&D to manufacturing will be presented. The differences between twin screw and single screw extrusion will be discussed with information on other extrusion processes. 

Overcoming Agitation Challenges in Cold Pearl Surfactant Blends

Ian Lutz, Solvay

Pearlescent additives have been used for centuries to impart an iridescent quality to a wide range of products including cosmetic, home care, and personal care formulations.  Currently, the state of the art technology choice for delivering shine and opacity to a formulation is cold pearl surfactant blends.  These blends are flowable, concentrated dispersions of waxy-crystalline structures in an aqueous surfactant matrix, providing a highly flexible and economical solution to appearance enhancement needs.  The production of high-quality cold pearl blends presents varied and unique agitation challenges at each stage of the manufacturing process: production must alternately balance the processing demands presented by emulsion formation, non-Newtonian fluid flow, heat transfer and growth of the desired crystal structure. 

This presentation will provide background on the key drivers of cold pearl surfactant blend quality, discuss current manufacturing process limitations, and include a review of an agitation design intended to provide a more complete solution to the challenges posed by pearlescent blends.  Specific examples of the alternative agitation design at pilot and at industrial scale will be reviewed to illustrate the benefits of a purpose-built mixing arrangement.