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MET126 > Flotation > Flashcards

Flotation Flashcards

1
Q

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

A

Flotation

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2
Q

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

A

Flotation

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3
Q

froth product is the concentrate

A

direct flotation

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4
Q

froth product is the tailings

A

reverse flotation

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5
Q

What are the 2 types of flotation?

A

direct flotation and reverse flotation

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6
Q

Flotation is UNIQUE among applications in metallurgy, as it

involves all possible interfaces:

A

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

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7
Q

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

A

surface properties

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8
Q

the time it takes a particle to slide around a bubble

A

contact time

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9
Q

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

A

induction time

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10
Q

What are the three main parts of a mechanical cell?

A

froth zone, quiescent zone, mixing zone

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11
Q

What are the two main arts of the column cell?

A

Froth zone and collection zone

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12
Q

What are the two main types of cells?

A

mechanical cell and column cell

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13
Q

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

A

Collector

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14
Q

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

A

Non-polar end; Polar end

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15
Q

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

A

Non- polar end

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16
Q

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

A

Polar end

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17
Q

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

A

non-polar hydrocarbon group

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18
Q

What are the two mechanisms of adsorption?

A

Ion exchange and electrochemical reaction

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19
Q

Mechanisms of Adsorption:

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

A

Ion exchange

20
Q

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

A

electrochemical reaction

21
Q

used to control alkalinity

A

pH modifiers

22
Q

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

A

activators

23
Q

– used to lower the floatability of specific minerals

– makes a naturally hydrophobic mineral hydrophilic

A

Depressants

24
Q
  • these reagents disperse slimes which often agglomerate and cover
    the surfaces of larger particles, preventing them from being
    recovered
A

Dispersants

25
Q

– 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)

A

Frothers

26
Q

– 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

A

Frothers

27
Q 
- a liquid, and this includes
slurry, can only hold a certain
volume of gas before it
becomes over-agitated and
appears to "boil"
A

Boiling

28
Q
  • areas on a bubble that are
    free of particles and indicate
    that the froth is not
    completely loaded
A

windows

29
Q 
- reflects the mineral particles
being recovered
- if froth is completely barren,
it will appear clear to white
and milky
A

Color

30
Q

“how much did i get?”

A

recovery

31
Q

“how pure is it?”

A

grade

32
Q

to provide sufficient retention
time to achieve target
recovery

A

rougher

33
Q

to provide sufficient retention
time to achieve target
recovery

A

rougher

34
Q 
eliminates a large portion of
unwanted material as tailings,
thus greatly reducing the
volume of slurry reporting to
the next stages
A

rougher

35
Q

to produce the target grade

A

cleaner

36
Q 
eliminating entrained
particles recovered in the
rougher and exploiting the
differences in flotation rates
between high grade particles
and locked middlings
A

cleaner

37
Q

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

A

scavenger

38
Q

preparations done on pulp prior to separation

A

conditioning

39
Q

leads to lessening of retention time in flotation cell

also requires less agitation in the cell

A

conditioning

40
Q

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

A

re-grinding

41
Q

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

A

thickening

42
Q
  • 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
A

residence time

43
Q

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

A

plug flow

44
Q

Residence time:

particles and liquid are distributed evenly immediately upon entering the system

A

perfect mixing

45
Q

What are the impediments in flotation

A
  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

MET126 (5 decks)

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