Gravity Concentration

Question 1

most simple and economical of all concentration methods

Answer 1

Gravity Concentration

Question 2

mineral particles are separated by virtue of the differences in density

Answer 2

Gravity Concentration

Question 3

What are the 3 categories under Gravity Concentration?

Answer 3

separation in vertical currents, separation in streaming currents, dense- medium separation

Question 4

What are the methods under vertical current GC?

Answer 4

elutriation, jigs

Question 5

What are the methods under separation in streaming currents?

Answer 5

panning, sluice boxes, spiral concentrators, reichert cone, shaking table, centrifugal concentrators

Question 6

• a process of sizing particles by means of an

upward current of fluid

Answer 6

Elutriation

Question 7

• uses one or more sorting columns where the
feed is separated into two fractions by their
terminal velocities

Answer 7

Elutriation

Question 8

• particles < d will move up the column; > d will
report to underflow
• “enhanced decantation”

Answer 8

Elutriation

Question 9

• consists of stratification of
particles into layers of different
densities caused by repeated
upward and downward current of
fluid to a very thick suspension of
mixed particles to settle or fall for
short periods of time

Answer 9

Jigging

Question 10

• normal settling of solids through water
• for shorter travel depths, it is dependent only on densities of
the solids and the

Answer 10

Differential Initial Acceleration (DIA)

Question 11

• increased pulp density; each mineral particle is covered w/ thin
film of water
• slurry acts as a viscous fluid

Answer 11

Hindered Settling

Question 12

• at the end of the stroke, when the bed contracts, the ↑d
particles interlock, leaving interstitial spaces
• lower d particles move along the spaces by gravity

Answer 12

Consolidation Trickling

Question 13

What is an ideal jigging process?

Answer 13

Combination of the 3 mechanisms: DIA, Hindered Settling, & Consolidation Trickling

Question 14

What are the 5 different types of Jig?

Answer 14

Harz jig, Denver mineral jig, Radial jig, (IPJ) In Line Pressure Jig, Baum Jig, Batac Jig

Question 15

• used as preliminary concentration of heavy- metal ores
• most commonly used for gold
• heavy minerals regardless of their size settle
to the bottom of the pan, and the lighter
materials remain on top

Answer 15

Panning

Question 16

• one of the most primitive GC
equipment
• inclined launder, narrowing from
200mm to 25mm

Answer 16

Pinched Sluices/ Troughs

Question 17

• Feed: 50-65% solids

Answer 17

Pinched Sluices/ Troughs

Question 18

• separation is a combined effect of
centrifugal action with multi-plane sluicing
in a particularly controlled sink-float
medium

Answer 18

Spiral Concentrators

Question 19

• Feed: 15-45% solids, 75μm-3mm

Answer 19

Spiral Concentrators

Question 20

• wash water is added at the inner edge
of stream and flows outwardly, carrying
the low-density minerals to the outer
radius

Answer 20

Spiral Concentrators

Question 21

• the heavier particles settle, the fines at the
upper layers
• an annular slot at the bottom accomplishes
the separation
• designed for higher capacities; 65-100
Mt/h

Answer 21

Reichert Cone

Question 22

• Feed: 55-70% solids; 30μm – 3mm

Answer 22

Reichert Cone

Question 23

• consists of an inclined deck with parallel
riffles along the long axis
• deck is vibrated longitudinally by a
mechanism w/c allows for a slow forward
stroke and a rapid return

Answer 23

Shaking Table

Question 24

• generally lowest capacity of all GCs

Answer 24

Shaking Table

Question 25

• Feed: 2-15 Mt/h; 100μm-1.5mm; 25% solids

Answer 25

Shaking Table

Question 26

The stroke of the mechanism and the flowing film of water subjects the minerals to 2 forces. What are these forces?

Answer 26

- Table motion, longitudinal to the table | - Flowing water film, across the table

Question 27

• may be visualized as rolling the deck of a shaking table into a drum

Answer 27

Centrifugal Concentrators

Question 28

• Knelson and Falcon concentrators

Answer 28

Centrifugal Concentrators

Question 29

• The drum is rotated so fast that the normal gravitational pull is many times increased • The “heavy” minerals report to the concentric rings (riffles), the “lights” flow with the film of water

Answer 29

Centrifugal Concentrators

Question 30

• a compact batch centrifugal concentrator with an active fluidized bed to capture heavy minerals • centrifugal force up to 200 times that of gravity

Answer 30

Knelson Concentrator

Question 31

• a centrifugal concentrator that can treat particles of sizes 10 μm to 6 mm • generally used for feeds in which the dense component to be recovered is a very small fraction of the total material

Answer 31

Knelson Concentrator

Question 32

What are the 3 types of Falcon Concentrator?

Answer 32

Semi-batch (200-300G), Continuous (300G), Ultrafine (600G)

Question 33

The smooth-walled lower portion is for particle stratification and then a fluidized upper portion is used for the collection of the heavier particles. The machine is stopped periodically to rinse and collect the valuable concentrate from the bowl.

Answer 33

Semi-batch (200-300G)

Question 34

Operates by using a smooth-walled, rotating bowl to stratify the material into heavier and lighter fractions then uses pneumatic valves to control the amount of heavy material that reports to the concentrate collection stream. It does not use any fluidization water and relies entirely on centrifugal force for separation.

Answer 34

Continuous (300G)

Question 35

Uses a smooth-walled bowl for particle stratification with a pneumatically controlled rubber lip for heavy material collection. The machine is stopped periodically to rinse and collect the valuable concentrate from the bowl

Answer 35

Ultrafine (600G)

Question 36

also known as sink and float or heavy media separation

Answer 36

Dense Media Separation

Question 37

2 principal applications: • widely used to pre-concentrate crushed material prior to grinding (METALS) • produce a commercially graded end-product (COAL)

Answer 37

Dense Media Separation

Question 38

- most useful for coarsely aggregated ores & ores w/ light gangue - problems w/ presence of low-value, high SG minerals - cannot be applied for finely disseminated valuable mineral on gangue host rock

Answer 38

Dense Media Separation

Question 39

- has the ability to make sharp separations at any required density, with a high degree of efficiency, even in the presence of high percentages of near-density material *Minerals w/ lighter SG than fluid will float, while those heavier will sink

Answer 39

Dense Media Separation

Question 40

for fractionating low-density materials such as coals

Answer 40

Solution of Salts

Question 41

• calcium chloride

Answer 41

Solution of Salts

Question 42

• zinc sulfate

Answer 42

Solution of Salts

Question 43

• zinc sulfate

Answer 43

Solution of Salts

Question 44

for fractionating high and low SG minerals

Answer 44

Organic Heavy Liquids

Question 45

• tetrabromoethane w/ white spirit or carbon tetrachloride

Answer 45

Organic Heavy Liquids

Question 46

• bromoform with carbon tetrachloride

Answer 46

Organic Heavy Liquids

Question 47

• diiodomethane w/ triethyl orthophosphate

Answer 47

Organic Heavy Liquids

Question 48

have certain advantages over organic liquids

Answer 48

Aqueous Solutions

Question 49

sodium polytungstate

Answer 49

Aqueous Solution

Question 50

• Clerici solution (thallium formate – thallium malonate solution)

Answer 50

Aqueous Solution

Question 51

utilizes supplementary weighting force produced in a solution of a paramagnetic salt or ferrofluid when situated in a magnetic field gradient

Answer 51

Magnetic Fluids

Question 52

<15% by vol (Newtonian fluids)

Answer 52

Suspension of Solids in Water

Question 53

• galena

Answer 53

Suspension of Solids in Water

Question 54

• ferrosilicon (82% Fe, 15-16% Si) – for metalliferrous ores

Answer 54

Suspension of Solids in Water

Question 55

• magnetite – for coal preparation

Answer 55

Suspension of Solids in Water

Question 56

What are the 2 different types of Separating Vessels?

Answer 56

Gravitational Vessels, Centrifugal Vessels,

Question 57

What are the 3 sub-types of gravitational vessels?

Answer 57

Wemco Cone Separator, Drum Separator, Two- component Drum Separator,

Question 58

What are the 5 sub-types of Centrifugal Vessels?

Answer 58

Dense Medium Cyclone, Vorsyl Separator, LARCODEMS, Dyna Whirpool Separator, Tri- flo Separator

Question 59

What are the three elements of DMS circuits?

Answer 59

De- sliming stage, Reclaiming Circuit for Media Recovery, Densifiers

Question 60

– to prevent the media from changing its density by presence of fines

Answer 60

De- sliming stage

Question 61

– consists of: • Vibrating drainage screens / washing sprays to recover 90% of media • Magnetic Separators / Flotation Cells to clean media from fines

Answer 61

Reclaiming Circuit for Media Recovery

Question 62

– to maintain density of media

Answer 62

Densifiers