Size Separation

1
Size Separation

• Nicole Tramp
• Clinton Foster
• Met 351
• 10-19-09

2
Introduction

• Procedure
• Sieves
• Agitators
• Data
• Sieve Problems
• Conclusion
• References

3
Procedure

• Prepare a representative sample of 100 grams
• Place the sample into the top sieve
• Mesh size of your choice
• Place stack into a mechanical sieve shaker for 15
  minutes
• Weigh powder remaining on each sieve and in the
  bottom pan
• To the nearest 0.1g
• Total all the weights
• Calculate and report percentages of each sieve
• To the nearest 0.1

4
Sieves
Standard U.S. sieve series Standard U.S. sieve series Standard U.S. sieve series
Sieve designation, mesh Sieve openings Sieve openings
Sieve designation, mesh µm in.
30 600 0.0232
40 425 0.0164
50 300 0.0116
60 250 0.0097
80 180 0.0069
100 150 0.0058
140 106 0.0041
200 75 0.0029
230 63 0.0024
325 45 0.0017

• Wire cloth sieves
• Square mesh patterns
• Table of US standard sieve series

5
Agitators

• Hand Shaking
• Gyratory motion
• Gyratory motion with tapping
• Mechanical shaking
• Mechanical vibration
• Electromagnetic vibration
• Oscillating air column
• Vacuum

6
Data
Sieve calibration results for two sieve stacks (in percentage of sample weight passing and cumulative percentage of sample weight retained) Sieve calibration results for two sieve stacks (in percentage of sample weight passing and cumulative percentage of sample weight retained) Sieve calibration results for two sieve stacks (in percentage of sample weight passing and cumulative percentage of sample weight retained) Sieve calibration results for two sieve stacks (in percentage of sample weight passing and cumulative percentage of sample weight retained) Sieve calibration results for two sieve stacks (in percentage of sample weight passing and cumulative percentage of sample weight retained)
Mesh Size Sample Sample Cumulative sample Cumulative sample
Mesh Size weight passing, weight passing, weight retained, weight retained,
Mesh Size Sieve Sieve Sieve Sieve
Mesh Size stack 1 stack 2 stack 1 stack 2
20 99.5 99.6 0.5 0.4
30 76.3 83.5 23.7 16.5
40 58.7 58.8 41.3 41.2
50 32.2 32.6 67.8 67.4
70 13.8 14.1 86.2 85.9
100 6.3 6.4 93.7 93.6
140 2.3 2.6 97.7 97.4
200 0 0.1 100 99.9
Pan 0 0 100 100

• Compare the sieves by both
• percentage of sample weight
• cumulative percentage of sample retained

7
Sieve Problems

• Overloaded Sieves
• Blinded Sieves
• Damaged Sieves
• Irregularly shaped particles
• Agglomeration

8
Overloaded Sieves

• Sieve surface becomes crowded
• Oversized particles
• Near-mesh particles
• Weight of oversized material tends to
• Wedge the near-mesh particles into openings
• Blocking passage of additional particles

9
Blinded Sieves (blanked sieves)

• Near-mesh particles become entrapped in the
  openings
• Can brush particles out
• Can use an ultrasonic wash to remove

10
Damaged Sieves

• May have
• Torn mesh
• Stretched mesh
• Distorted mesh
• Inspect sieves regularly with a microscope

11
Irregularly shaped particles

• Particles that may pass through a sieve opening
  in a specific orientation only
• Vibrating or shaking should be sufficient to
  change orientation of all particles

12
Agglomeration

• Prevents fine particles from passing through mesh
  openings
• Electrostatic charges may cause particles to
  attract one another

13
Conclusion

• May be a way to separate plagioclase out
• May not be ideal to separate the pyroxenes

14
References

• ASM Handbooks Online
• http//products.asminternational.org/hbk/index.jsp