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Principles of Metallurgy > Mineral Processing: Separation > Flashcards

Mineral Processing: Separation Flashcards

1
Q

Generally accepted as the most simple and economical of all concentration methods
* Mineral particles are separated by virtue of the differences in density - the greater the difference in density between two minerals, the more easily they can be separated
* However, the smaller the particles, the more powerful are fluid and viscous forces relative to gravity

A

Gravity Concentration

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2
Q

– typified by jigging, which takes advantage of differing rates of settlement

A

separation in vertical currents

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3
Q
  • A process of sizing particles by means of an upward current of fluid
  • Reverse of gravity sedimentation; Stokes’ Law applies
  • Uses one or more sorting columns where the feed is separated into two fractions by their terminal velocities
  • Consider a sorting column with a constant water pressure supply from the bottom, calibrated to separate minerals of separating size d
  • Particles < d will move up the column; > d will report to underflow
  • “enhanced decantation
A

Elutriation

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3
Q

particles are immersed in a bath containing a medium of intermediate density so that some particles float and others sink

A

dense-medium separation

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4
Q

or ‘thin film sizing‘ – shaking table or a spiral separator

A

separation in streaming currents

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5
Q
  • Also known as Gold Panning and Miner’s Pan
  • Used as preliminary concentration of heavy-metal ores
  • Most commonly used for gold
A

Panning

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6
Q
  • the minerals to be separated are stratified in a bed rendered fluid by a pulsating current below to effect stratification
  • The bed “dilates”, accommodating heavier, finer particles to settle through the interstices of larger particles; larger particles experience hindered settling
A

Jigging

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7
Q

Uses the difference in magnetic properties between minerals
* Separation by applying magnetic fields:
– Magnetic valuable minerals from gangue (Fe3O4 from SiO4)
– Non-magnetic valuable mineral (SnO2 from (Fe,Mn)WO4
– Removal of tramp metals

A

Magnetic Separation

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8
Q

repelled along the lines of magnetic force to a point where the field intensity is smaller

A

Diamagnetic

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9
Q

attracted along the lines of magnetic force to points of greater field intensity

A

Paramagnetic

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10
Q

Ni, Co, Mn, Cr, Ce, Ti, O and Pt group elements also exhibit paramagnetism
* For most cases, PM of minerals is due to the presence of IRON

A

Ferromagnetism

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11
Q

high surface charge

A

Insulators

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12
Q

no charging effect

A

Conductors

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13
Q
  • A method of wet concentration of ores in which separation of valuable minerals from gangue is effected by utilizing the surface-chemical properties of the minerals to enable physical separation
  • Generally, 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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14
Q

– The only flotation process which is of commercial importance

A

Froth Flotation

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15
Q

When air bubbles are passed through a slurry containing fine mineral particles, with certain minerals capable of attachment to the bubble

A

Froth Flotation

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16
Q

UNIQUE among applications in metallurgy, as it involves all possible interfaces:
– Air-Water (Gas-Liquid)
– Mineral-Water (Solid-Liquid)
– Air-Mineral (Gas-Solid)

A

Flotation

16
Q

is capable of concentrating selectively and successively a number of different minerals which originally coexisted in a given ore deposit

A

Froth Flotation

17
Q
  • Is the force acting parallel to the surface of a bulk of substance, which opposes any effort to extend the interfacial area
  • The natural tendency of a liquid to decrease its surface
  • Denoted by γ
A

Surface Tension

18
Q

Collection of bubbles; governed by the equation:

A

FROTH

19
Q

maintenance of a body of bubbles at and above the upper surface of the pulp

A

FROTHING

20
Q

Frothing Agents
* also referred to as

A

FROTHERS

21
Q

lowers ST; the reagent concentrates at the bubble surfaces

A

Organic frothers

22
Q

increases ST; they concentrate away from the surface

A

Inorganic Frothers

23
Q

– does not dissociate with H2O; limited use

A

Non-ionizing

24
Q

polar compound end dissociates with H2O; general type of collectors

A

Ionizing

25
Q
  • Have the most commercial importance
  • May easily be applied to a variety of minerals by using knowledge in zeta potentials
A

Ionizing Collectors

26
Q
  • Surface-chemical reactions involves the adsorption of ions; especially free-flowing ions to a solid surface
  • This occurrence is present in mineral-water couple in Flotation
A

Adsorption

27
Q
  • Time required for the disjoining film to drain such a thickness prior to rupture
  • Should be less than contact time for flotation to be possible!
A

Induction Life

28
Q

adsorption due to chemical reaction

A

Chemisorption

29
Q

This explains the fact that solids tend to attain surface charges when introduced in water

A

Adsoprtion

29
Q

– as a function of electrical behavior of ions

A

Physical Adsorption

30
Q
  • The essential prerequisite to separation by flotation is selective collector-coating
A

Conditioning

31
Q
  • Reagents used in flotation to control the action of a collector on minerals, in order to intensify or reduce its water repellent effect on the mineral surface
A

Modifiers

32
Q
  • Chemically altering the surface of a mineral that is exhibiting natural floatability
  • Making a naturally hydrophobic mineral hydrophilic
A

Depression

33
Q
  • Essentially the semantic opposite of Depression
  • Enabling a mineral that has previously no activity with a collectornto adsorb collector ions for bubble attachment
A

Activation

33
Q

most important sa regulators

A

pH Modification

33
Q

One of the primary objects of flotation research is to discover the optimum pH for any given combination of reagents and ore
* Most flotation plants treating sulfide ores operate with an alkaline pulp to give optimum metallurgy as well as to keep corrosion at a minimum

A

pH Modification

34
Q

make collector action more selective with regard to minerals, thus ensuring a reasonably sharp separation from each other in flotation

A

Regulators

35
Q

Pulp is normally held at ______ temperature

A

Ambient

Principles of Metallurgy (13 decks)

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