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Questions and Answers
What is a primary advantage of wet sieving compared to dry sieving?
What is a primary advantage of wet sieving compared to dry sieving?
Which factor contributes to the sedimentation of particles in a gravitational sedimentation method?
Which factor contributes to the sedimentation of particles in a gravitational sedimentation method?
In centrifugal methods, what is the purpose of using a single cylindrical centrifuge?
In centrifugal methods, what is the purpose of using a single cylindrical centrifuge?
What is the primary difference in the operation of sedimentation and elutriation methods?
What is the primary difference in the operation of sedimentation and elutriation methods?
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Why do very fine particles not sediment efficiently under the influence of gravity?
Why do very fine particles not sediment efficiently under the influence of gravity?
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What is a key difference between size separation by sieving and particle size analysis?
What is a key difference between size separation by sieving and particle size analysis?
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Which description accurately characterizes the agitation methods in dry sieving techniques?
Which description accurately characterizes the agitation methods in dry sieving techniques?
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What is a disadvantage of using brushing methods in dry sieving techniques?
What is a disadvantage of using brushing methods in dry sieving techniques?
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Which method of dry sieving utilizes centrifugal force to enhance separation?
Which method of dry sieving utilizes centrifugal force to enhance separation?
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In size separation by sieving, what characteristic is used to describe the sieves?
In size separation by sieving, what characteristic is used to describe the sieves?
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Study Notes
Particle Size Separation
- The classification of particles into separate ranges of size
- The removal of particles from gases or liquids
Size Separation Methods
Sieving
- Similar to particle size analysis, but utilizes larger sieves
- Sieves should be resistant to chemical action, stainless steel is recommended
- Can be done by dry or wet sieving
Dry Sieving Techniques
- Agitation methods use vibrations to facilitate particle passage through pores. Gyration is another method that uses rotation to reorient particles
- Brushing methods utilize a brush to reorientate particles on the sieve's surface, preventing pore blockage
- Centrifugal methods utilize high-speed rotors and forced air to separate particles
Wet Sieving
- More efficient than dry sieving
Size Separation By Fluid Classification
Sedimentation Methods
- Gravitational methods use chambers containing a suspension of particles in a liquid. After a predetermined time, particles of a specific size are removed.
- Continuous settling chamber employs a shallow container with a driving force. The force is divided, one component is horizontal due to particle velocity, the other is vertical due to gravity. Sedimentation occurs with the coarsest particles closest to the inlet and finest furthest from the inlet.
Centrifugal Methods
- Centrifugal methods increase the driving force of sedimentation, separating particles by size using cylindrical or multiple chamber centrifuges
Elutriation Methods
- Elutriation uses fluids flowing in the opposite direction of sedimentation to separate particles. The velocity of the fluid dictates the size fraction.
- Upward airflow elutriator classifies particles based on their ability to be carried upward by airflow.
- Multistage elutriators utilize a series of columns with increasing diameters. The fluid velocity decreases as the diameter increases, separating various particle sizes.
Cyclone Methods
- Reverse-flow cyclone is a common method for separating particles from fluid streams.
- The fluid velocity creates a vortex that forces particles outward.
- The conical section forces particles downward, and finer particles leave with the fluid through the vortex finder.
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Description
Test your knowledge on various particle size separation methods including sieving techniques, wet and dry sieving, and sedimentation methods. Learn about the principles behind these techniques and explore their applications in different fields. This quiz is perfect for students and professionals in materials science and engineering.
