Lesson 2 Flashcards
1
Q
also termed as Mineral
Dressing, Ore Dressing, Mineral Beneficiation,
Milling, is defined as the Mechanical Separation of
valuable minerals (ore concentrate) from valueless
minerals (gangue).
A
Mineral Processing
2
Q
The two (2) fundamental operations in mineral
processing are
A
Liberation and Separation
3
Q
Fundamental Operation sa Mineral Processing
the release of the valuable
ore from the waste minerals
A
Liberation
4
Q
Fundamental Operation sa Mineral Processing
concentration of these valuable
minerals from the gangue
A
Separation
5
Q
performed in between mining
and production of metal
products
ma get get pow rana sabti lang jud huhuhu
between daw??? so unsa man
A
Mineral Processing
6
Q
OBJECTIVE
- To bring the valuable mineral or the final product
into suitable technical condition as required by the
process - Undesired constituents of the original ore must be
removed or reduced below the specified units
A
Technical
7
Q
- To provide the cheapest way to eliminate the
unwanted minerals - Reduce unit material handling costs
- Mineral Processing must be cost-efficient!
COST????COST!!!! KWARTA
A
Economic
8
Q
Concentration of desired mineral =
Tinipid langs
A
Freight Savings
9
Q
The essential prerequisite for the
separation of an ore into valuable and
waste fractions
prereq daw oh
fundamental sis sa min pro
A
Liberation
10
Q
Waste Rock Minimization =
para asa pud
A
Improve metal purity
10
Q
Effective Material Reduction =
para asa pud
A
Reduced Treatment charge
11
Q
it is impracticable if the 1st step
has not been successfully accomplished!
A
Separation
12
Q
– Uncrushed rock
unsa sha na size
A
grains, grain size
13
Q
Crushed rock
unsa na siya na size
A
Particles, Particle size
14
Q
Particles can consist of a
single mineral;
A
Free particle
15
Q
- particle size reduction by breaking,
crushing, or grinding of ore, rock, coal,
or other materials - It is a critical component in most mineral
processing flowsheets and can serve
several purposes
Goals: LIBERATION and
SEPARATION - Done either wet or dry
- Consumes a lot of energy
(>40% of total Mine/Mill
consumption)
Unit operation ni sha bayot ha
A
Comminution
15
Q
When a particle consists of
2 or more minerals,
A
Locked Particle
16
Q
Stages of Crushing
PRIMARY
ENUMERATE YOT
A
– Jaw Crushers
– Gyratory Crushers
16
Q
Stages of Crushing
SECONDARY
ENUMERATE YOT
A
– Cone / Gyrasphere Crushers
– Roll Crushers
– Hammer Mills
– Impactors
17
Q
– Consists of 2 crushing faces or jaws,
* one stationary and rigidly mounted
* one jaw reciprocates to and from the face in a small
throw
– The different types feature the positioning of the
pivot of the movable jaw
A
Jaw Crusher
18
Q
– Invented in (1)____ by (2)________
– Movable jaw is pivoted at the (3)____ by cross
shafts
– A motor drives an eccentric shaft, transfers
the reciprocating motion to the jaw
unsa ni siya na type?
A
BLAKE TYPE
- 1885
- Eli Whitney Blake
- Top
19
Q
Dodge Type
– The movable jaw is fixed at the (1)_____
– Key feature is large reduction ratio and a
closely-sized product
– Disadvantage is its low-capacity operation,
since the choke point coincides with the point
of least motion
unsa ni siya na type?
A
DODGE TYPE
- bottom
20
Q
– Modifications of Dodge and Blake
– The motion of the movable shaft is a direct
result of the circular motion of the eccentric
shaft
– Uses less space than Blake or Dodge
wow the connection!!!
A
Single Toggle/Overhead Eccentric
21
Q
– Originally patented by
(1)______ in (2)_____
– Relative motion of the
crushing faces is due to
gyration motion of an
eccentrically mounted
cone
UNSA NI NA CRUSHER!??!?!??!
A
GYRATORY CRUSHER
- Philetus Gates
- 1881
22
– At any cross-section,
there are in effect 2
sets of jaws opening
and closing like jaw
crushers
Gyratory Crusher
23
Three types of Gyratory Crushers
| ENUMERATE YOT
– Suspended spindle
– Supported spindle
– Fixed spindle
24
There is a fixed crushing
surface (______) shaped
like an inverted cone
frustrum
| unsa pud?
Concaves
25
and a movable crushing
surface (_____), also
conically shaped, w/c
gyrates w/in the interior of
the concave cone
Mantle
26
(1)
* Lighter than the heavy-duty, rugged *primary
Crushers
* Maximum feed size ~ (2)____
* “clean” feed (no harmful constituents)
* Final feed is of size suitable for grinding
circuit
1. Secondary Crushers
2. 15 cm
27
DIfference between CONE CRUSHERS and GYRATORY CRUSHERS
| kadtong naka box kay di ko kabalo unsaon hays
## Footnote
yes tong opposite opposite langs
Cone crushers
1. Short Spindle
2. Spindle is not suspended
3. Downward Flare bowl
4. Spring-protected bowl
Gyratory crushers
1.Longer spindle
2. Suspended spindle
3. Upward flare concave
4. No spring for the concave
28
– tertiary crushing
– Crushing by interparticle comminution
– Short, Flat-angle liners
________ action:
– Combination of impact
and attrition
– No single-layer
crushing occurs!
| interparticle comminution ako term ani kay unique....
## Footnote
unique!??!??!?!
Gyradisc Crusher
29
* The rolls are fitted with a series of inter-meshing
teeth or “slugs” w/c protrude from the roll
surfaces
* Crushing action is by compression and ripping
* Used for softer, sticky materials for larger Rr
## Footnote
sharo naa nay term na slugs oh
Toothed/Slugger Roll Crusher
29
– Spherical crushing head
– The crushing bowl is held by spring in
compression (vs. tension in CC’s)
## Footnote
SPHERE DAW BAYOT
Gyrasphere Crushers
30
* Consists of two horizontal cylinders
revolving towards each other
* Spring loaded rolls are adjusted for the
set; held back against the solidly mounted
roll
* Single pressure only! (vs. continuous w/
JC, GC, CC)
## Footnote
roll on hahahhaa
Roll crushers
31
* Comminution by impact;
sharp blows on free-falling
rock
* Used on materials behaving
plastically on slowcompression crushing
* Uses beaters to transfer
kinetic energy to particles
HAmmer mills/Impactors
32
(1)
* The hammers are attached
to a rotor w/c sweeps along
the path of free falling
rocks
* Pivoted hammers
* Hammers and breaking
plates are made of
(2)______
1. Hammer Mills
2. Manganese Steel
33
HAMMER MILLS
* Hammers can weigh up to (1)_____
* Feed size up to (2) _____
* Rotor speeds between (3) _____
## Footnote
hahahahha keri pa beh?
1. 100kg
2. 20cm
3. 500-3000 RPM
34
(4)_______
* Used for coarser crushing; (1) ____
* Fixed hammers
* Grinding path – successive breaker
plates with decreasing clearances;
produces better control of product size
* Rotor speed is (2)____
* Feed rate (3)______
1. F ~ 1.5 m
2. 250 – 500 RPM
3. 1500 – 3000 MT/h
4. Impactors
35
* Impact crushing + High-intensity grinding +
multi-particle pulverizing
## Footnote
pulverizing!!!!!
Tidco Barmac Crusher
36
* Operates like a cylindrical trommel
Coal Breakers
36
– Grinding in one pass
Open Circuit
37
* “Mechanized Mortar and Pestle”
* Rr = 150:1
Stamp Mills
37
* Last stage of comminution
* Size reduction by impact + abrasion
* Done either wet or dry
* Performed primarily on rotating cylindrical steel
vessels (tumbling mills)
* May or may not use grinding medium (balls or rods)
Grinding
38
– Controlled by feed rate (<45% mill volume)
## Footnote
kadtong hentai gale HUIEEEEEE
Overflow
39
– The mill discharge is passed through a sizing
product
– The oversize particles are re-circulated
Closed Circuit
40
– Prevents early discharge of oversize and
grinding medium
– Removal of fines, prevents over-grinding
Grate Discharge
41
* Mixture of ore, water, and grinding media
Mill Charge
42
– Minerals are
susceptible to physical
and chemical changes
with water
Dry Grinding
43
– Lower kWh/Mt
– Higher Mt/m3 mill
volume
– Closer product control
by classification
– Elimination of dust
– Simpler handling;
pumps and launders
Wet Grinding
44
– Rolling motion of the charge down to the toe
– Leads to finer grinding by abrasion (↑liner
wear)
Cascading
45
– Parabolic path taken by charge as projected
by lifting of the mill
– Coarse grinding by impact (↓liner wear)
Cataracting
46
– Charge is carried around in a fixed position
Centrifuging
47
it is adjusted to control the
trajectory of the GM; to hit the ore, not the
mill liners!
Mill Speed
47
TM’s are normally operated bet. __% -
__% of critical speed
50-90%
48
* Uses cast iron rods as grinding medium
* Rr
= 15-20:1
* Length is 1.5-2.5x the diameter
* Max length of rods = 6m; 25-150mm Φ
* Rated based on power consumption
* Operated at 35% mill volume; 50%-65%
critical speed; 65-85% solids
## Footnote
cast iron rods daw oh
Rod Mills
49
* Rod Mills are practically always run in
______
| in unsa?
Open Circuit
50
* Uses forged steel balls as
grinding medium
* Length is 1-1.5x the diameter
* Operated at 65%-80% solids;
40%-50% mill volume; 70%-80%
critical speed
* 10 uses 5cm-10cm balls; 20 uses
2cm-5cm
* Mill capacity is increased by
length; specific capacity is
increased by diameter (energy)
## Footnote
forged steel balls daw oh
Ball Mill
51
Higher mill rotation speeds – ______ is
dominant
Cataracting
51
Ball Mills are often operated in _________ to minimize over-grinding
CLosed Circuit
52
* The action of the ore grinding upon itself
* Uses tumbling to effect grinding; little or no
medium!
* Rr up to 250
* L:D ~ 1:2
* SAG – 6%-10% mill volume ball charge
* Operated at 75%-90% critical speed
Autogenous/ SAG Mills
53
* The main mechanism for grinding is by
| by????
Abrasion
54
the size at w/c the particles
inside the AG is already too small for
efficient grinding
Critical Size
55
Useful Range of ELUTRIATION
## Footnote
AHAHHAHHAHAHHAHAHA
40-5
55
Useful Range of TEST SIEVES
## Footnote
AHHAHHAHAHHAAHHAH
100000 – 10
55
* Segregation of Materials into products
characterized by difference in size
* Screening and Classification
| Unit Operation in Mineral Processing
Sizing
56
Useful Range of SEDIMENTATION (CENTRIFUGE)
## Footnote
heheheh
5-0.05
56
Useful Range of MICROSCOPY
## Footnote
bleee
50 – 0.25
57
Useful Range of SEDIMENTATION (GRAVITY)
## Footnote
sge gow
40 – 1
58
Useful Range of ELECTRON MICROSCOPY
## Footnote
korek
1-0.005
59
* One of the oldest methods
* Most widely used due to effective
size range
* Done by passing a known weight
of sample through successively
finer apertures to determine the
weight for each fraction
* Wet or dry
* Agitated
Sieve Analysis
60
COMPLICATION IN SIEVING
| duha ni sila
-irregularly shaped particles
-near size particles "blinding"
61
*Designated by nominal aperture sizes
– Sides of square or diameter of circle aperture
* Mesh no. ≈ # of square apertures/inch2
test sieves
62
* Machine Sieving using the (1)____
* Sieves are stacked in increasing mesh
no.
* Sample is placed on (2)_____, coarsest
sieve
* Agitated vertically and horizontally
* Fraction retained per sieve is weighed
1. Ro-tap
2. topmost
62
* Prevent entry of undersize into crushing
machines
* Prevent oversize from moving onto the
next stage in closed circuit grinding
* Prepare a closely sized end product
Industrial Screening
63
STATIONARY SCREENS
(?)
– 20mm – 300mm, 1000tph max
– 20 – 500 deck angle
– Uses heavy parallel bars
Grizzly
64
STATIONARY SCREENS
– >50μm, 180m3/hr
– Curved screen w/
horizontal wedge bars
– Slurry enters tangentially to
the bend
– Peeling action of the slurry
bed
Sieve Bend
65
STATIONARY SCREEN
– 6 –55mm
– Slightly inclined, rotating
cylindrical screen
– May be made in series, or with
concentric cylinders of increasing
aperture sizes (compound
trommel)
Revolving Screen/Trommels
66
MOVING SCREEN
(?)
– 250μm – 25cm
– Most important screens
– Multi-decks
Vibrating Screens
67
# ?
WHat is the basis for separation????
| ?
## Footnote
?
velocity of the particles as the grains fall through a fluid medium
68
shear forces between
medium and mineral surface
Viscous Resistance
69
due to displacement
of fluid by the mineral
Turbulent Resistance
70
– pt. of 0 acceleration
Gravity ≈ Resistant Forces
Terminal Velocity
71
* a system with a large volume of medium
relative to particles
* No particle crowding (<15% solids w/w)
Free Settlings of Particles
72
* ↑pulp density; each mineral particle
is covered w/ thin film of water
* Slurry acts as a viscous fluid; only
coarse particles can penetrate
* Most important concept in
classification / sorting columns
* Larger particles settle at the
bottom, finer ones are carried
away by current (w/ scouring
action)
Teeter Condition
72
(1)
* The case where there is an increase in
pulp density (>15% solids w/w)
* ↑pulp density, ↑viscosity, resistance is
mainly due to (2)____
1. Hindered Settling
2. Turbulence
72
* Continuous classifier that
uses centrifugal force to
accelerate the settling rate of
particles
* Widely used in MP for fine
separation and closed- circuit
grinding due to short retention
time
Hydrocyclone
72
TYPES OF CLASSIFIERS
* Mechanical Classifiers
– Rake Classifier
– Spiral Classifiers
→Pulp feed is introduced to inclined through;
coarser, heavier particles settle at the bottom
and is dragged against a flow of liquid
→Finer particles report to overflow discharge
Horizontal Current Classifiers
73
TYPES OF CLASSIFIERSSSSS
* Vertical type: hindered settling; effects on density
* Multiple (series) sorting columns w/ rising water
current from bottom
* Faster currents at the 1st column, slowest at the last
– results in the grading of the slurry from coarser,
denser particles to finer ones!
* Volume of chambers increase successively
Hydraulic Classifiers
73
Mechanism for removal of coarse / dense
minerals is a rake system moving up an
incline
Rake Classifier
74
* Uses a continuous moving spiral to move
sands up a slope
* May be used at steeper slopes (de-H2O)
Spiral/Screw Classifier
75
HYDROCYCLONE
* The feed is introduced
under pressure by
(1)______ entry w/c
imparts a swirling motion
of the pulp
* This generates a (2)______
inside, w/ a low pressure
zone along the vertical
axis
1. Tangential
2. Vortex
76
* Separation of valuable minerals
* Based on the physical characteristics of
minerals
Concentration
77
* Solid/liquid separation by thickeners
and filters
Dewatering
78
* Bins, conveyors, feeders, pumps, etc.
Auxiliary Operations
