7/24/2019 Mechanical Separation Techiques

http://slidepdf.com/reader/full/mechanical-separation-techiques 1/13

1/23/2008

1

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.

7/24/2019 Mechanical Separation Techiques

http://slidepdf.com/reader/full/mechanical-separation-techiques 2/13

1/23/2008

2

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

7/24/2019 Mechanical Separation Techiques

http://slidepdf.com/reader/full/mechanical-separation-techiques 3/13

1/23/2008

3

Centrifuge

Feed : Liquid + solid or another immiscible liquid

Separating agent: Centrifugal force

Product: Liquid + solid or another immiscible liquid

Principle of separation : density difference

7/24/2019 Mechanical Separation Techiques

http://slidepdf.com/reader/full/mechanical-separation-techiques 4/13

1/23/2008

4

Centrifuge,liquid – liquidseparation

1. Feed2. Separated solids3. Clear liquid

Centrifuge,

liquid – solid

separation

(clarification)

7/24/2019 Mechanical Separation Techiques

http://slidepdf.com/reader/full/mechanical-separation-techiques 5/13

1/23/2008

5

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

7/24/2019 Mechanical Separation Techiques

http://slidepdf.com/reader/full/mechanical-separation-techiques 6/13

1/23/2008

6

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

7/24/2019 Mechanical Separation Techiques

http://slidepdf.com/reader/full/mechanical-separation-techiques 7/13

1/23/2008

7

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

7/24/2019 Mechanical Separation Techiques

http://slidepdf.com/reader/full/mechanical-separation-techiques 8/13

1/23/2008

8

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

7/24/2019 Mechanical Separation Techiques

http://slidepdf.com/reader/full/mechanical-separation-techiques 9/13

1/23/2008

9

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

7/24/2019 Mechanical Separation Techiques

http://slidepdf.com/reader/full/mechanical-separation-techiques 10/13

1/23/2008

10

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

7/24/2019 Mechanical Separation Techiques

http://slidepdf.com/reader/full/mechanical-separation-techiques 11/13

1/23/2008

11

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

7/24/2019 Mechanical Separation Techiques

http://slidepdf.com/reader/full/mechanical-separation-techiques 12/13

1/23/2008

12

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

7/24/2019 Mechanical Separation Techiques

http://slidepdf.com/reader/full/mechanical-separation-techiques 13/13

1/23/2008

13

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