Flotation

Question 1

a method of wet concentration in which separation is effected by
utilizing the difference in Physico-chemical properties of particles of
various minerals

Answer 1

Flotation

Question 2

separation is made possible by attaching a mineral to a
bubble and letting it float above the bulk phase, leaving the other
“unwanted” mineral submerged

Answer 2

Flotation

Question 3

froth product is the concentrate

Answer 3

direct flotation

Question 4

froth product is the tailings

Answer 4

reverse flotation

Question 5

What are the 2 types of flotation?

Answer 5

direct flotation and reverse flotation

Question 6

Flotation is UNIQUE among applications in metallurgy, as it

involves all possible interfaces:

Answer 6

– Air-Water (Gas-Liquid)
– Mineral-Water (Solid-Liquid)
– Air-Mineral (Gas-Solid)

Question 7

Flotation relies on differences in ______________ among minerals to achieve separation.

Answer 7

surface properties

Question 8

the time it takes a particle to slide around a bubble

Answer 8

contact time

Question 9

the time required for the particle to penetrate the film and reach
the air in the bubbles

Answer 9

induction time

Question 10

What are the three main parts of a mechanical cell?

Answer 10

froth zone, quiescent zone, mixing zone

Question 11

What are the two main arts of the column cell?

Answer 11

Froth zone and collection zone

Question 12

What are the two main types of cells?

Answer 12

mechanical cell and column cell

Question 13

used to provide a water-repellant surface on the mineral to be floated

Answer 13

Collector

Question 14

The collector is composed of two parts with very distinct properties. What are these?

Answer 14

Non-polar end; Polar end

Question 15

The collector is composed of two parts with very distinct properties. Which one is a hydrocarbon radical or hydrophobic?

Answer 15

Non- polar end

Question 16

The collector is composed of two parts with very distinct properties. Which one has compounds that have sufficient activity in water or hydrophilic?

Answer 16

Polar end

Question 17

The collector is composed of two parts with very distinct properties. These are oriented outward forming a hydrophobic pseudo surface while the polar ion or the solidophil group are attached with the mineral surface via chemisorption or ionic bonding

Answer 17

non-polar hydrocarbon group

Question 18

What are the two mechanisms of adsorption?

Answer 18

Ion exchange and electrochemical reaction

Question 19

Mechanisms of Adsorption:

ex: Xanthate ions may adsorb onto a particle by replacing sulphate ions on the surface

Answer 19

Ion exchange

Question 20

Mechanisms of Adsorption:
transfer of electrons from one substance to
another

Answer 20

electrochemical reaction

Question 21

used to control alkalinity

Answer 21

pH modifiers

Question 22

modify the mineral surface which cause a particular mineral to float with a collector when it would otherwise not float

Answer 22

activators

Question 23

– used to lower the floatability of specific minerals

– makes a naturally hydrophobic mineral hydrophilic

Answer 23

Depressants

Question 24

• these reagents disperse slimes which often agglomerate and cover
  the surfaces of larger particles, preventing them from being
  recovered

Answer 24

Dispersants

Question 25

– used to produce froth of adequate durability to permit the removal of mineral carrying bubbles from the flotation machine – the molecule comprises a hydrocarbon chain and head groups, typically OH‾ (hydroxyl)

Answer 25

Frothers

Question 26

– added since pure water does not froth thus, it is necessary to add minute quantities of reagents to effect frothing – essential to maintaining large quantities of small bubbles in the pulp

Answer 26

Frothers

Question 27

``` - a liquid, and this includes slurry, can only hold a certain volume of gas before it becomes over-agitated and appears to "boil" ```

Answer 27

Boiling

Question 28

- areas on a bubble that are free of particles and indicate that the froth is not completely loaded

Answer 28

windows

Question 29

``` - reflects the mineral particles being recovered - if froth is completely barren, it will appear clear to white and milky ```

Answer 29

Color

Question 30

"how much did i get?"

Answer 30

recovery

Question 31

"how pure is it?"

Answer 31

grade

Question 32

to provide sufficient retention time to achieve target recovery

Answer 32

rougher

Question 33

to provide sufficient retention time to achieve target recovery

Answer 33

rougher

Question 34

``` eliminates a large portion of unwanted material as tailings, thus greatly reducing the volume of slurry reporting to the next stages ```

Answer 34

rougher

Question 35

to produce the target grade

Answer 35

cleaner

Question 36

``` eliminating entrained particles recovered in the rougher and exploiting the differences in flotation rates between high grade particles and locked middlings ```

Answer 36

cleaner

Question 37

to remove as much of the remaining valuable mineral as possible and produce a final tailing

Answer 37

scavenger

Question 38

preparations done on pulp prior to separation

Answer 38

conditioning

Question 39

leads to lessening of retention time in flotation cell also requires less agitation in the cell

Answer 39

conditioning

Question 40

done to liberate middling particles concentrated in certain flotation streams and to create clean, fresh surfaces

Answer 40

re-grinding

Question 41

used to control the percent solids ahead of some units in the circuit and to remove excess soluble species such as metal ions in the water

Answer 41

thickening

Question 42

- the longer particles spend in a flotation cell, the more likely they are to float - calculated by dividing the system volume by the volumetric flow rate through the system

Answer 42

residence time

Question 43

Residence time: if particles did all spend the same amount of time; constant feed and discharge rate

Answer 43

plug flow

Question 44

Residence time: | particles and liquid are distributed evenly immediately upon entering the system

Answer 44

perfect mixing

Question 45

What are the impediments in flotation

Answer 45

1. liberation 2. ions in water 3. surface oxidation 4. precipitates on surfaces 5. coagulation 6. temperature 7. contamination 8. hydrophobic and sulphidic gangue 9. mineralogy