Forth Flotation

2. Froth Flotation

3. Presented By:
M. Ali Mohsin(MME-16-04)

4. Flotation
 Flotation is a selective process and can be
used to achieve specific separation from
complex ores such as lead-zinc copper-
zinc etc
 Flotation is the most important and
versatile mineral processing technique.

5. Principle Of Flotation
Flotation is a physico-chemical separation
process that utilizes the difference in surface
properties of the valuable minerals and the
unwanted minerals. This process commences
with comminution.
 The ore is ground to fine powder and wetted
with water to form a slurry.

7. Separation mechanisms
 The process of separation of mineral includes
three important mechanisms which are :
1. True flotation, i.e. selective attachment to air
bubbles.
2. Entrainment in the water which passes
through the froth.
3. Aggregation, i.e. physical entrapment
between the particles attached to air
bubbles in froth.
 True flotation dominates the recovery of
valuable minerals and the other two decide
the separation efficiency between the
valuable and the gangue.

8. Ways of flotation
 There are two ways of flotation:
1. Direct flotation
2. Reverse flotation
 Direct flotation in which the mineral is
attached to the froth and the gangue
remains in the tailing.
 Reverse flotation in which the gangue is
attached to the froth and the minerals
remains in the tailing.

9. Classification of minerals
 Polar
 Non-polar
 All minerals are classified into polar or non-polar
types according to their surface characteristics.
 Since water is a polar molecule, polar mineral
surfaces tend to be hydrophilic.
 Whereas, nonpolar mineral surfaces tend to be
hydrophobic.
 The goal is to make the mineral surface
hydrophobic so the minerals will attach to the
bubbles in the froth.

10. Collectors Frothers
 These are organic
compounds used for
enhancing the
hydrophobicities of the
selected minerals, by
adsorption of its molecules
or ions to the mineral
surface and reducing the
stability of the hydrated
surface separating the
mineral surface and air
bubbles.
 Frothers are added to
stabilize bubble formation
in the pulp phase, to create
a reasonably stable froth to
allow selective drainage
from the froth of entrained
gangue

11. Regulators Activators
 Regulators, or modifiers,
are used extensively in
flotation to modify the
action of the collector,
either by intensifying or by
reducing its water-repellent
effect on the mineral
surface.
 These reagents activates the
mineral surface towards the
action of the collectors, by
altering their chemical
properties. Thus, they are
referred as the friends of
collectors.

12. Depressants pH Modifiers
 These reagents deactivate the
mineral surface towards the
action of collectors, by
altering their chemical
properties. Hence, they are
referred as the enemies of the
collectors.
 There are mainly two
categories of depressants,
 Inorganic (e.g. sodium
cyanide, zinc sulphate etc.)
 Organic (or polymeric e.g.
starch, tannin etc.)
 The selectivity in floatation
process is dependent on
delicate balance between the
reagent concentration and the
pH.
 This pH factor is modified
with the help of the substances
called pH Modifiers.
Alkalinity in solution is
maintained by the addition of
lime and sodium carbonate.
Sulphurous and sulpuric acids
are used to lower the pH