This document provides an overview of froth flotation, which is a process for separating minerals and coal by taking advantage of differences in the surfaces of materials. It works by making some materials hydrophobic so they can attach to air bubbles. There are two main types of flotation: direct and reverse. The key factors that determine whether a material will float include its wettability and the chemistry involved through collectors, frothers, and other reagents. Proper equipment and control of operation parameters like feed rate and pH are also important for effective flotation. Challenges include particle properties and achieving high selectivity in separating target from waste materials.

1. Fundamentals of
Froth Flotation
Authors:
Himesh Patel
Aditya Kumar
Fuel and Mineral Engineering Department
Indian School Of Mines, Dhanbad.

2. What is froth flotation?
Froth flotation, is a physicochemical method of concentrating fine
minerals and coal.
It can be stated that Flotation is a physiochemical separation
process that utilises the difference in surface properties of the
valuable minerals and the gangue minerals.
E.g.
Removing silicate minerals from iron ores.

3. Principle of Froth Flotation
Flotation is a physiochemical separation process that utilises the
difference in surface properties of the valuable minerals and the
unwanted gangue minerals.
The material recovery process by flotation comprises three
mechanisms:
Selective attachment to air bubbles
Entrainment in the water which passes through the froth.
Physical entrapment between particles in the froth attached to air
bubbles

5. Ways of Flotation
1. Direct Flotation: In which the mineral is attached to the froth
and the gangue remains in the tailings.
E.g. Hematite flotation
2. Reverse Flotation: In which the gangue is attached to the
froth and minerals remain in tailing.
E.g. Quartz flotation

7. Mechanics of Flotation
The basis of Froth Flotation is the difference in the WETTABILITY
of the mineral and gangue particles.
On the basis of Wettability of particles are classified as
HYDROPHOBIC and HYDROPHILIC.
The valuable minerals can attach to the air bubbles , only if they are
Hydrophobic. Once they reach the surface, due to the buoyancy of the
air bubbles, the particle-bubble contact can sustain only if they form a
stable froth.
The stability of the froth depends on the strength of the attachment of
the bubble to the mineral surface. This strength can be estimated with
the help of YOUNG-DUPRE EQUATION, which relates the strength
of attachment to the interfacial energies.

8. WHERE, in the above equation, ΓW/A, ΓS/A, ΓS/W are the SURFACE
ENERGIES between water-air, solid-air, solid-water interface and θ is the
CONTACT ANGLE.

9. Flotation System
Chemistry Components :
Collectors, Frothers, Activators, Depressants, pH Control.
Equipment Components:
Cell Design, Agitation, Air Flow, Cell Bank Configuration, Cell
Bank Control.
Operation Components:
Feed Rate, Mineralogy, Particle Size, Pulp Density, Temperature.

10. Chemistry Components
1. A collector is a chemical that attaches to the mineral surface and
produces a hydrophobic (water-fearing) surface.
E.g. oils, xanthates, fatty amines
2. Frothers are liquids that produce the froth or foam on which the flotation
process depends.
E.g. pine oil, MIBC (Methyl Isobutyl Carbinol)
3. Activators are specific compounds that make it possible for collectors to
adsorb onto surfaces that they could not normally attach to.
E.g. copper, ZnS(s) + Xanthate-
4. Depressants have the opposite effect of activators, by preventing
collectors from adsorbing onto particular mineral surfaces.
E.g. Cyanides, Limes, Organic Depressants
5. pH CONTROL: The surface chemistry of most minerals is affected by
the pH.

11. Flotation tank cell

12. Jameson Cell

13. Flocculation
 Flocculation involves the formation of much more open
agglomerates than those resulting from coagulation and relies upon
molecules of reagent acting as bridges between separate suspended
particles.
 Selective flocculation of the desired minerals in the pulp, followed
by separation of the aggregates from the dispersed material, is a
potentially important technique, although plant applications are at
present rare.

14. Present Challenges
•Particle size and density
•Pulp density
•Air bubble size
•Agitation intensity
•Conditioning time
•Residence time
•Nature of Particle (Particle
surface charge)
•pH of slurry
•Type of reagent
•Amount of reagents
•Frother stability

15. Flotation In Coal
Froth flotation is the most commonly used process to recover and
upgrade the portion of the coal preparation plant feed that has a particle
size smaller than 150 microns. Problems that occur when employing
froth flotation in the coal industry include
i) Coal surfaces that are weakly-to-moderately hydrophobic, and
ii) flotation systems that are overloaded and limited by insufficient
retention time.

16. Flowsheet

19. Reference
• Wills, B.A. and Napier-Munn Tim, “Mineral Processing
Technology”, Elsevier(2005)
• Kavatra, S.K., “Flotation Fundamentals”
• Ray, H.S. and Sridhar, R., “Extraction of Non- Ferrous Metals”
• Saracoglu, Mehmet, "FROTH FLOTATION PERFORMANCE
ENHANCEMENT BY FEED CAVITATION AND MAGNETIC
PLASTIC PARTICLE ADDITION" (2013). Theses and
Dissertations--Mining Engineering. Paper 9.
http://uknowledge.uky.edu/mng_etds/9
• www.imn.gliwice.pl/public/doc/maszyny-flotacyjne_en.pdf
• http://www.metso.com/miningandconstruction/mm_sepa.nsf/WebW
ID/WTB-041102-2256F-C598E?OpenDocument#.UzNPOvmSwRo