chapter  14
44 Pages

Addressing Powder Flow and Segregation Concerns during Scale-Up of Nutraceutical Solid Formulations

Thomas Baxter, James Prescott, Roger Barnum, and Jayant Khambekar

CONTENTS

14.1 Introduction ..................................................................................................348 14.1.1 Introduction to Flowability ............................................................... 349 14.1.2 Introduction to Blending ................................................................... 350 14.1.3 Introduction to Segregation .............................................................. 351

14.2 Typical Flow and Segregation Concerns ...................................................... 352 14.2.1 Common Flow Problems .................................................................. 352

14.2.1.1 No Flow .............................................................................. 352 14.2.1.2 Erratic Flow ....................................................................... 354 14.2.1.3 Fine Powder Flow Concerns: Two-Phase Flow Effects ..... 354

14.2.2 Flow Patterns .................................................................................... 355 14.2.3 Common Segregation Mechanisms .................................................. 357

14.2.3.1 Material Properties That Affect Segregation ..................... 357 14.2.3.2 Sifting Segregation............................................................. 358 14.2.3.3 Fluidization Segregation .................................................... 358 14.2.3.4 Dusting Segregation ........................................................... 359

14.3 Measurement of Flow Properties and Segregation Potential........................ 361 14.3.1 Cohesive Strength Tests: Preventing Arching and Ratholing ........... 361

14.3.1.1 Test Methods ...................................................................... 361 14.3.1.2 Calculation of the Minimum Required Outlet

Dimensions to Prevent Arching: Mass Flow Bin............... 363 14.3.1.3 Calculation of Minimum Required Outlet Dimensions

to Prevent Ratholing: Funnel Flow Bin .............................364 14.3.2 Wall Friction: Determining Hopper Angles for Mass Flow ............. 365

14.3.2.1 Test Method........................................................................ 365

14.1 INTRODUCTION

This chapter provides guidance in designing bulk solid (“powder”) handling equipment to provide consistent, reliable flow and to minimize segregation. The principles discussed in this chapter can be applied to analyzing new or existing equipment designs. The principles can also be used to compare different powders using the various test methods discussed.