Solids Handling
ZARS Project
Terry Ring
Particle Segregation
Golden Rules of Sampling
• To get a representative sample for analysis– Chemical analysis
– Particle size distribution analysis
• Rule 1 – A powder should be sampled when in motion
• Rule 2– The whole stream of powder should be taken for many
short increments of time in preference to part of the stream being taken for the whole time.
Particle Size
Counting Particles
Histogram Representation Particle Size Distribution
Cumulative Distribution Representation of PSD
Errors in PSD
0
1.0
2.0
Exp
ecte
d E
rror
in %
Errors in PSD
Blending Powders
Classification
• Powder is separated into two streams– Fine Particles– Coarse Particles
• Equipment– Sieves– Cyclones– Centrifuge– Filter– Venturi Scruber– Electrostatic Precipitator
Cyclone
Sieve & Filter Classification
1 10 100 1 1030
0.5
1
Size (microns)
Size
Sel
ectiv
ity
1 10 100 1 1030
0.5
1
Size (microns)
Size
Sel
ectiv
ity
Cyclone Classification
How to Blend Powders
• V- Blender– A in one arm, B in other arm– After 1/2 Turnover
• A/2 & B/2 in center
– After 1 Turns• A/2 & B/2 in each arm
• Is it well mixed??
Segregation
• Particle size distributions should be matched to prevent segregation in a pile of powders
Sedimentation
9
2 2 gRV fst
Laminar Flow
Sedimentation
Dust
• Sedimentation/Diffusion Equilibrium
• Wind velocity prevents settling