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Questions and Answers
The cumulative weight percentage up to 0.5 μ particle size class is 30.7%.
The cumulative weight percentage up to 0.5 μ particle size class is 30.7%.
True (A)
26.76% of the total sample is less than 1.5 μ.
26.76% of the total sample is less than 1.5 μ.
False (B)
The total cumulative weight is 40 grams.
The total cumulative weight is 40 grams.
False (B)
All particles with a size class of 4.0 μ have a cumulative weight percentage of 1.3%.
All particles with a size class of 4.0 μ have a cumulative weight percentage of 1.3%.
The cumulative weight percentage up to 2.0 μ particle size class is 85.2%.
The cumulative weight percentage up to 2.0 μ particle size class is 85.2%.
73.24% of the total sample is less than 1.5 μ.
73.24% of the total sample is less than 1.5 μ.
The particle size class of 1.0 μ has a cumulative weight percentage of 30.7%.
The particle size class of 1.0 μ has a cumulative weight percentage of 30.7%.
The cumulative weight percentage up to 3.0 μ particle size class is 94.1%.
The cumulative weight percentage up to 3.0 μ particle size class is 94.1%.
The main objective of size separation is to increase the production cost.
The main objective of size separation is to increase the production cost.
The size separation range for sieving is 0.5-100μm.
The size separation range for sieving is 0.5-100μm.
The wire mesh of the sieves should be of rectangular cross-section.
The wire mesh of the sieves should be of rectangular cross-section.
Data on particle size distributions are normally collected by centrifugation.
Data on particle size distributions are normally collected by centrifugation.
The separation method used affects the size-separation efficiency.
The separation method used affects the size-separation efficiency.
Particle size measurement is only dependent on the nature of the material to be sized.
Particle size measurement is only dependent on the nature of the material to be sized.
Sieving is a method used for particle size measurement in the range of 0.1-10μm.
Sieving is a method used for particle size measurement in the range of 0.1-10μm.
Particle size distributions are always presented in graphical form.
Particle size distributions are always presented in graphical form.
The particle size class of 0.5 μ has a cumulative weight of 98.62%
The particle size class of 0.5 μ has a cumulative weight of 98.62%
The graph on the right shows the relative amount of particles in each size class.
The graph on the right shows the relative amount of particles in each size class.
The cumulative frequency curve is a step function.
The cumulative frequency curve is a step function.
The particle size class of 1.5 μ has a weight of 1.5 grams.
The particle size class of 1.5 μ has a weight of 1.5 grams.
The cumulative weight of particles in the size class of 0.1 μ is 1.38 grams.
The cumulative weight of particles in the size class of 0.1 μ is 1.38 grams.
The graph on the left shows the cumulative weight of particles in each size class.
The graph on the left shows the cumulative weight of particles in each size class.
The particle size class of 5 μ has a cumulative weight of 100%
The particle size class of 5 μ has a cumulative weight of 100%
The cumulative frequency curve can be used to determine the percentage weight of particles in each size class.
The cumulative frequency curve can be used to determine the percentage weight of particles in each size class.
The cumulative weight percentage is plotted against the particle size class on the x-axis.
The cumulative weight percentage is plotted against the particle size class on the x-axis.
Microscopy is a method to determine particle size distribution that can measure particles up to 1000m.
Microscopy is a method to determine particle size distribution that can measure particles up to 1000m.
Sedimentation methods are based on the principle of size separation by sedimentation, which utilizes the differences in settling velocities of particles with different diameters.
Sedimentation methods are based on the principle of size separation by sedimentation, which utilizes the differences in settling velocities of particles with different diameters.
Stokes' Law predicts the settling velocity of small spheres in fluid, either air or water, and is given by the equation w = g.
Stokes' Law predicts the settling velocity of small spheres in fluid, either air or water, and is given by the equation w = g.
Centrifugal sedimentation is used for particle size ranges up to 1000m.
Centrifugal sedimentation is used for particle size ranges up to 1000m.
Gravitational sedimentation is used for particle size ranges from 4-1000m.
Gravitational sedimentation is used for particle size ranges from 4-1000m.
Sedimentation is the process by which particulates settle to the top of a liquid and form sediment.
Sedimentation is the process by which particulates settle to the top of a liquid and form sediment.
A simple technique of sedimentation classification uses a chamber containing a suspension of solid particles in a liquid, which is usually water.
A simple technique of sedimentation classification uses a chamber containing a suspension of solid particles in a liquid, which is usually water.
In a sedimentation method, the feed enters the outer wall of the bowl and the suspension passes through each chamber in turn.
In a sedimentation method, the feed enters the outer wall of the bowl and the suspension passes through each chamber in turn.
The coarse particles deposit in the outer chamber and the increasingly fine particles deposit on the subsequent chambers.
The coarse particles deposit in the outer chamber and the increasingly fine particles deposit on the subsequent chambers.
Elutriation is a technique in which the fluid flows in the same direction as the sedimentation movement.
Elutriation is a technique in which the fluid flows in the same direction as the sedimentation movement.
In elutriation, particles are divided into different size fractions depending on the density of the fluid.
In elutriation, particles are divided into different size fractions depending on the density of the fluid.
The highest velocity is found in the tube walls and the lowest velocity at the tube center.
The highest velocity is found in the tube walls and the lowest velocity at the tube center.
The size of particles that will be separated depends on their position in the tube, the smallest particles in the center, the largest towards the outside.
The size of particles that will be separated depends on their position in the tube, the smallest particles in the center, the largest towards the outside.
The suspension is introduced tangentially at fairly low velocity in cyclone methods.
The suspension is introduced tangentially at fairly low velocity in cyclone methods.
In cyclone methods, the rotary movement takes place within the vessel at low velocity.
In cyclone methods, the rotary movement takes place within the vessel at low velocity.
Study Notes
Particle Size Separation
- Particle size separation is a process by which powder particles are removed from gases or liquids.
- The objective of size separation is to:
- Recover valuable products or byproducts
- Prevent environmental pollution
- The efficiency of size separation depends on:
- Particle and fluid properties
- The separation method used
- Separation efficiency is determined as a function of the effectiveness of a given process in separating particles into oversize and undersize fractions.
Size Separation Methods
- Sieving:
- Size separation ranges: 5-10000μm
- Most widely used method of analysis
- Different grades of sieves are used for sifting the powders
- The wire mesh of the sieves should be of uniform circular cross-section and possess adequate strength to avoid distortion and be resistant to chemical action.
- Method selection considerations:
- Nature of the material to be sized
- Estimated particle size and particle size range
- Solubility
- Ease of handling
- Toxicity
- Flowability
- Intended use
- Cost
- Specification requirements
- Time restrictions
Particle Size Measurement
- Data presentation:
- Table form
- Graph form
- Statistical summarizing:
- Particle size distributions are normally collected by sieving
- Cumulative weight percentage can be calculated
Sedimentation Methods
- Separation ranges:
- Centrifugal sedimentation up to 4μm
- Gravitational sedimentation, 4-1000μm
- Principle:
- Size separation by sedimentation utilizes the differences in settling velocities of particles with different diameters
- Stokes' Law predicts the settling velocity of small spheres in fluid
- Sedimentation techniques:
- A. Simple technique: uses a chamber containing a suspension of solid particles in a liquid
- B. Alternative: uses a series of chambers with increasing distances from the axis
Elutriation Methods
- Principle:
- Elutriation is a technique in which the fluid flows in an opposite direction to the sedimentation movement
- Particles move vertically downwards while the fluid travels vertically upwards
- Types of elutriation:
- Based on counter flow of fluid (air/water) and settling particles through vertical columns
- Uses a distribution of velocities across the tube in which a fluid is flowing
Cyclone Methods
- Principle:
- The suspension is introduced tangentially at fairly high velocity, so that a rotary movement takes place within the vessel.
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Description
Learn about particle size separation, its objectives, and the factors affecting its efficiency. Understand the importance of size separation in recovering valuable products and preventing environmental pollution.
