Literature survey on the prediction of powder caking

Literature Survey Concerning the Prediction of
Powder Caking
April 2012.

1. ABSTRACT
Powder caking (agglomeration) occurs thanks to a number of mechanical and chemical
mechanisms, being the migration and absorption of water, and the handling/storing
conditions often the most influential. Prediction of caking comes from assessing key
properties to achieve a good understanding of thepowdered material's behaviour. Control
can be achieved by managing/improving environmental conditions in order to maintain feed
or product in an optimal flowing state, based on the assessments results.

2. TABLE OF CONTENTS
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ABSTRACT ....................................................................................................................... 1
TABLE OF CONTENTS....................................................................................................... 1
INTRODUCTION ............................................................................................................... 2
LITERATURE SURVEY ....................................................................................................... 3
4.1. Caking and Flowability of powders........................................................................... 3
4.2. Assessment of powders' flowability ......................................................................... 4
4.2.1. Uniaxial stress tests .......................................................................................... 4
4.2.2. Shear tests and flowfunction............................................................................ 5
4.2.3. Rheology tests .................................................................................................. 6
4.3. Characterization of powders' flowability .................................................................. 7
4.3.1. Caking index ..................................................................................................... 7
4.3.2.Flow function .................................................................................................... 7
4.3.3. Basic flow energy (BFE) ..................................................................................... 8
4.4. Variables influencing the flowability of powders ...................................................... 9
4.4.1. Moisture sorptionisotherms............................................................................. 9
4.4.2. Glass transition temperature (Tg) .................................................................... 11
4.5. Christakis et al. model for caking behaviour prediction .......................................... 12
5. EXPERIMENTAL RESULTS............................................................................................... 13
5.1. Sorption isotherms for various dairy powders ........................................................ 13
5.2. Glass transition temperature, Tg, for various dairy powders .................................. 16
5.3. Christakis et al. model compared to experimental data. ........................................ 18
6. DISCUSSION.................................................................................................................. 18
7. CONCLUSION ................................................................................................................ 19
8. REFERENCES .................................................................................................................. 20

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Prediction of powder caking: A big asset for the food, chemicaland pharmaceutical industry.

2012

3. INTRODUCTION
The food, chemical and pharmaceutical industry handles large amounts of solid products per
year from raw feeds, additives and intermediates through to manufactured products, where
powders are the principal matter.
Powdered materials are generally susceptible to caking. They are affected by more variables
than liquids and solids. Their...