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Mechanical SeparationBy Kanthamoon W.
Mechanical separation techniques
Various techniques based on differences in:
1. densities,
2. sizes,
3. surface properties,
4. fluidities,
5. electrostatic charging,
6. magnetic properties.
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Mechanical separation techniques based
on density differencesSettling
Feed : Liquid + solid or another immiscible liquid
Separating agent: Gravity
Product: Liquid + solid or another immiscible liquid
Principle of separation : density difference
Settling
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Centrifuge
Feed : Liquid + solid or another immiscible liquid
Separating agent: Centrifugal force
Product: Liquid + solid or another immiscible liquid
Principle of separation : density difference
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Centrifuge,liquid – liquidseparation
1. Feed2. Separated solids3. Clear liquid
Centrifuge,
liquid – solid
separation
(clarification)
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Cyclone separation
Feed : Gas + solid or liquid
Separating agent: Flow (inertia)
Product: Gas + solid or liquid
Principle of separation : density difference
Cyclone separators
Air cleaningSize classification
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Mechanical separation techniques based
on size differencesFiltration
Feed : Liquid + solid
Separating agent: Pressure reduction (energy) + filter
medium
Product: Liquid + solid
Principle of separation : size of solid larger than pore size
of filter medium
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Cake filtration
CAKE FILTRATION
MEDIUM
CAKE
FLOW
•ADDITIVE
RESISTANCES
•CAKE MAY CLOG
THE MEDIUM, CAUSING
THE MEDIUM RESISTANCE
TO INCREASE(PERMEABILITY WILL DROP)
L
+
∆=
m
m
c
c
k
L
k
L
P AQ
µ
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Operation sequences in
cake filtration
1 23
4
Mesh demister
Feed : Gas + liquid
Separating agent: Pressure reduction (energy) + wire mesh
Products: Gas + liquid
Principle of separation : size of liquid droplets larger thanpore size of filter medium, wetting of filter medium
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Mesh demister
Centrifugal filtration
Feed : Liquid + solid
Separating agent: Centrifugal force (energy) +filtermedium
Products: Liquid + solid
Principle of separation : size of solid larger than pore sizeof filter medium
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Mechanical separation technique basedon differences in surface properties
Flotation
Feed : Mixed, powdered suspended solids in liquid
Separating agent: Added surfactants, rising air bubbles
Products: Two solids, clear liquid
Principle of separation : tendency of surfactants/rising airbubbles to adsorb preferentially on one of the solidspecies
Wastewater treatment using flotation and settling
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Mechanical separation technique based ondifferences in fluidities
Expression
Feed : Liquid + solid
Separating agent: Mechanical force
Products: Liquid + solid
Principle of separation : tendency of liquid to flow underapplied pressure gradient
Application of expressingusing screw presses
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Mechanical separation technique basedon differences in electrical charging
Electrostatic precipitation
Feed : Gas + fine solids
Separating agent: Electric field
Products: Gas + fine solids
Principle of separation : charge on fine solid particles
Electrostatic precipitation
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Mechanical separation technique based ondifferences in magnetic properties.
Magnetic separation
Feed : Mixed powdered solids
Separating agent: Magnetic field
Products: Two solids
Principle of separation : Attraction of material in
magnetic field
Magnetic separation
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