Particle Size Separation Methods
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Questions and Answers

What percentage of the total sample is less than 1.0 μ?

  • 67.33%
  • 11.05%
  • 26.76% (correct)
  • 46.79%
  • What is the total percentage of weight in the given data?

  • 100.00% (correct)
  • 100.01%
  • 99.99%
  • 99.00%
  • What is the cumulative weight percentage of particles with size class 0.1 μ?

  • 5.9%
  • 26.76%
  • 11.05%
  • 1.3% (correct)
  • What is the total weight of the sample?

    <p>30.92 grams</p> Signup and view all the answers

    What is the particle size class with the highest cumulative weight?

    <p>3.5 μ</p> Signup and view all the answers

    What percentage of the total sample is more than 1 μ?

    <p>73.24%</p> Signup and view all the answers

    What does the x-axis represent in the histogram?

    <p>Particle size class (μ)</p> Signup and view all the answers

    What is the cumulative weight percentage of particles with size class 1.5 μ?

    <p>50.0%</p> Signup and view all the answers

    What is the purpose of a cumulative frequency curve?

    <p>To represent the size distribution of the sample</p> Signup and view all the answers

    What is the weight percentage of particles with a size class of 1.5 μ?

    <p>1.38%</p> Signup and view all the answers

    How many particles have a size class less than or equal to 0.5 μ?

    <p>11.05% of the total sample</p> Signup and view all the answers

    What is the cumulative weight of particles with size class 2.0 μ?

    <p>5.96 grams</p> Signup and view all the answers

    What is the term for a graph that shows the relative amount of particles in each size class?

    <p>Histogram</p> Signup and view all the answers

    What does the y-axis represent in the histogram?

    <p>Cumulative weight (%)</p> Signup and view all the answers

    What is the weight percentage of particles with size class 3.0 μ?

    <p>8.9%</p> Signup and view all the answers

    What is the term for a smooth curve that represents the size distribution of the sample?

    <p>Cumulative frequency curve</p> Signup and view all the answers

    What is the primary objective of size separation?

    <p>To recover valuable products or byproducts and prevent environmental pollution</p> Signup and view all the answers

    What factors affect the efficiency of size separation?

    <p>The particle and fluid properties, and the separation method used</p> Signup and view all the answers

    What is the range of particle size that can be separated using sieving?

    <p>5-10000μm</p> Signup and view all the answers

    What is the importance of the uniform circular cross-section of the wire mesh in sieves?

    <p>To avoid distortion and ensure resistance to chemical action</p> Signup and view all the answers

    How can data on particle size distributions be normally collected?

    <p>By sieving</p> Signup and view all the answers

    What is the primary consideration when choosing a method for particle sizing?

    <p>The nature of the material to be sized</p> Signup and view all the answers

    What is the purpose of sieving in particle size separation?

    <p>To separate particles of different sizes</p> Signup and view all the answers

    How can the data on particle size distributions be presented?

    <p>In both table and graph forms</p> Signup and view all the answers

    What is the principle behind sedimentation methods?

    <p>Size separation by sedimentation utilizes the differences in settling velocities of particles with different diameters</p> Signup and view all the answers

    What is the range of particle sizes that can be separated using centrifugal sedimentation?

    <p>Up to 4 μm</p> Signup and view all the answers

    What equation predicts the settling velocity of small spheres in a fluid?

    <p>Stokes' Law</p> Signup and view all the answers

    What is the process by which particulates settle to the bottom of a liquid and form sediment?

    <p>Sedimentation</p> Signup and view all the answers

    What is the purpose of pipette in sedimentation methods?

    <p>To recover particles less than a given diameter</p> Signup and view all the answers

    What is the unit of measurement for particle size in the graph shown?

    <p>μm</p> Signup and view all the answers

    Which of the following is NOT a method to determine particle size distribution?

    <p>Chromatography</p> Signup and view all the answers

    What is the term for the settling velocity of small spheres in a fluid?

    <p>w</p> Signup and view all the answers

    What is the direction of fluid flow in an elutriation method?

    <p>Vertically upwards</p> Signup and view all the answers

    What happens to dense particles in an elutriation method?

    <p>They sediment down</p> Signup and view all the answers

    What determines the size of particles that will be separated in an elutriation method?

    <p>Their position in the tube</p> Signup and view all the answers

    What is the movement of the suspension in a cyclone method?

    <p>Rotary movement</p> Signup and view all the answers

    What happens to the largest particles in an elutriation method?

    <p>They are found in the center of the tube</p> Signup and view all the answers

    What is the direction of sedimentation movement in an alternative sedimentation method?

    <p>Vertically downwards</p> Signup and view all the answers

    What happens to the clarified liquid in an alternative sedimentation method?

    <p>It overflows from the largest diameter chamber</p> Signup and view all the answers

    What determines the separation of particles in an alternative sedimentation method?

    <p>Their size</p> Signup and view all the answers

    Study Notes

    Particle Size Separation

    • Definition: Solid separation is a process by which powder particles are removed from gases or liquids.
    • Objectives:
      • To recover valuable products or byproducts
      • To prevent environmental pollution

    Size-Separation Efficiency

    • Efficiency depends on:
      • Particle and fluid properties
      • Separation method used
    • Separation efficiency is determined by the effectiveness of a process in separating particles into oversize and undersize fractions

    Methods for Particle Size Measurement

    • Choosing a method for particle sizing depends on:
      • Nature of the material to be sized
      • Estimated particle size and particle size range
      • Solubility
      • Ease of handling
      • Toxicity
      • Flowability
      • Intended use
      • Cost (capital and running)
      • Specification requirements
      • Time restrictions

    Size Separation Methods

      1. Sieving:
      • Size separation ranges: 5-10000μm
      • Most widely used method of analysis
      • Different grades of sieves are used for sifting the powders
      • Wire mesh of the sieves should be of uniform circular cross-section, and should possess adequate strength to avoid distortion and be resistant to chemical action with the material to be sifted

    Statistical Summarization of Particle Size Distribution

    • Data on particle size distributions are normally collected by sieving
    • Presentation of data:
      • Table form
      • Graph form

    Cumulative Frequency Curves

    • A smooth curve that represents the size distribution of the sample
    • Readily shows the relative amount of particles in each size class
    • Readily shows the % of particles in each size class

    Methods to Determine Particle Size Distribution

    • Microscopy
    • Sieving methods
    • Sedimentation methods
    • Particle counting methods
    • Laser/Light diffraction methods

    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

    Alternative Sedimentation Methods

    • A. Simple Technique:
      • Suspension of solid particles in a liquid
      • After predetermined times, particles less than a given diameter can be recovered using pipette
    • B. Alternative:
      • Feed enters the center of the bowl and the suspension passes through each chamber in turn, at increasing distances from the axis
      • The solids settle onto the outer wall of each chamber and the clarified liquid emerges as an overflow from the largest diameter chamber

    Elutriation Methods

    • Elutriation is a technique in which the fluid flows in an opposite direction to the sedimentation movement
    • The particles move vertically downwards while the fluid travels vertically upwards
    • In the case of elutriation, particles are divided into different size fractions depending on the velocity of the fluid
    • Based upon counter flow of fluid (air/water) and settling particles through vertical columns

    Cyclone Methods

    • The suspension is introduced tangentially at fairly high velocity, so that a rotary movement takes place within the vessel

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    Description

    This quiz covers the process of solid separation, its objectives, and factors affecting size-separation efficiency. It also explores various methods used in particle size separation.

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