MECHANICAL SEPARATIONS

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MECHANICAL SEPARATIONS
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Course Outline

• Introduction to Separation Processes
• Role of Mechanical Separations in Chemical
  Engineering
• Fundamentals of different mechanical separations
  
• Filtration, Sedimentation, Clarification,
  Flotation, Centrifugal separations, Jigging,
  tabling, magnetic and electrostatic separations,
  Sonic Agglomeration
• Different types of mechanical separation
  equipment

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Introduction to Separation Processes

• Separation process is used to transform a mixture
  of substances into two or more distinct products.
  
• The mixture can be a combination of any two or
  more states solid-solid, solid-liquid,
  solid-gas, liquid-liquid, liquid-gas, gas-gas,
  solid-liquid-gas mixture, etc.

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Separation Process Mechanisms

• Phase creation
• Phase addition
• Barrier
• Solid agent
• External field

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How separation is carried out?

• In order to affect a separation, separating
  agents are needed in the form of either
• Energy input (heat, electricity, magnetism,)
• Withdrawal of energy ( cooling, freezing)
• Medium (filter, membrane, screens)
• May be any phase as well as any chemical

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Classification of Separation processes

• The classification can be based on the means of
  separation
• Mechanical Processes
• Chemical processes

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Why Separations are needed?

• Isolating valuable chemicals from mixtures
• Removing impurities from raw materials
• Purification of products

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Mechanical Separations

• Mechanical Separations are applicable to
  heterogeneous mixtures, not to homogenous
  solutions. The techniques are based on the
  physical differences b/w the particles such as
  size, shape or density.

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Advantages

• Relatively less Energy Requirements
• Ease of Operation
• Ease of Maintenance
• No special Feed pretreatment required
• Not applicable for separating Components in
  homogeneous phase
• Not versatile i.e. in same state may be one
  element can be separated and other dont.
• Applicable to low flow rates

Disadvantages
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Classification

• On the basis of characteristics
• Depending on the difference in size or shape
• Depending on the difference in phase density
• Depending on fluid and particle mechanics
• Depending on surface, electrical or magnetic
  properties
• On the basis of phases involved
• S-S
• L-L
• G-L
• L-G
• S-L
• L-S
• S-G

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Our focus will be the

• Solid Solid Separation
• Solid Liquid Separation
• Solid Gas Separation

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Solid Solid Separation

• Objective to separate the mixture of solids
  into two or more fractions
• Dry basis
• Screening
• Electrostatic
• magnetic
• Wet basis
• Classification

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Solid Liquid Separation

• Objective to separate the solids and liquid
  from each other
• Filtration
• Sedimentation gravitational settling
• Centrifugal separators

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Solid Gas Separation

• Objective to separate the solids from gas
• Filtration
• Gravitational settling
• Centrifugation

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Filtration
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Sedimentation
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Centrifugal Separation
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Magnetic Separation
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Electrostatic Separation