Lesson 2 Flashcards
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).
Mineral Processing
The two (2) fundamental operations in mineral
processing are
Liberation and Separation
Fundamental Operation sa Mineral Processing
the release of the valuable
ore from the waste minerals
Liberation
Fundamental Operation sa Mineral Processing
concentration of these valuable
minerals from the gangue
Separation
performed in between mining
and production of metal
products
ma get get pow rana sabti lang jud huhuhu
between daw??? so unsa man
Mineral Processing
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
Technical
- To provide the cheapest way to eliminate the
unwanted minerals - Reduce unit material handling costs
- Mineral Processing must be cost-efficient!
COST????COST!!!! KWARTA
Economic
Concentration of desired mineral =
Tinipid langs
Freight Savings
The essential prerequisite for the
separation of an ore into valuable and
waste fractions
prereq daw oh
fundamental sis sa min pro
Liberation
Waste Rock Minimization =
para asa pud
Improve metal purity
Effective Material Reduction =
para asa pud
Reduced Treatment charge
it is impracticable if the 1st step
has not been successfully accomplished!
Separation
– Uncrushed rock
unsa sha na size
grains, grain size
Crushed rock
unsa na siya na size
Particles, Particle size
Particles can consist of a
single mineral;
Free particle
- 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
Comminution
When a particle consists of
2 or more minerals,
Locked Particle
Stages of Crushing
PRIMARY
ENUMERATE YOT
– Jaw Crushers
– Gyratory Crushers
Stages of Crushing
SECONDARY
ENUMERATE YOT
– Cone / Gyrasphere Crushers
– Roll Crushers
– Hammer Mills
– Impactors
– 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
Jaw Crusher
– 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?
BLAKE TYPE
- 1885
- Eli Whitney Blake
- Top
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?
DODGE TYPE
- bottom
– 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!!!
Single Toggle/Overhead Eccentric
– 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!??!?!??!
GYRATORY CRUSHER
- Philetus Gates
- 1881
– At any cross-section,
there are in effect 2
sets of jaws opening
and closing like jaw
crushers
Gyratory Crusher
Three types of Gyratory Crushers
ENUMERATE YOT
– Suspended spindle
– Supported spindle
– Fixed spindle
There is a fixed crushing
surface (______) shaped
like an inverted cone
frustrum
unsa pud?
Concaves
and a movable crushing
surface (_____), also
conically shaped, w/c
gyrates w/in the interior of
the concave cone
Mantle
(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
- Secondary Crushers
- 15 cm
DIfference between CONE CRUSHERS and GYRATORY CRUSHERS
kadtong naka box kay di ko kabalo unsaon hays
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
– 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….
unique!??!??!?!
Gyradisc Crusher
- 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
sharo naa nay term na slugs oh
Toothed/Slugger Roll Crusher
– Spherical crushing head
– The crushing bowl is held by spring in
compression (vs. tension in CC’s)
SPHERE DAW BAYOT
Gyrasphere Crushers
- 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)
roll on hahahhaa
Roll crushers
- 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
(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)______
- Hammer Mills
- Manganese Steel
HAMMER MILLS
- Hammers can weigh up to (1)_____
- Feed size up to (2) _____
- Rotor speeds between (3) _____
hahahahha keri pa beh?
- 100kg
- 20cm
- 500-3000 RPM
(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)______
- F ~ 1.5 m
- 250 – 500 RPM
- 1500 – 3000 MT/h
- Impactors
- Impact crushing + High-intensity grinding +
multi-particle pulverizing
pulverizing!!!!!
Tidco Barmac Crusher
- Operates like a cylindrical trommel
Coal Breakers
– Grinding in one pass
Open Circuit
- “Mechanized Mortar and Pestle”
- Rr = 150:1
Stamp Mills
- 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
– Controlled by feed rate (<45% mill volume)
kadtong hentai gale HUIEEEEEE
Overflow
– The mill discharge is passed through a sizing
product
– The oversize particles are re-circulated
Closed Circuit
– Prevents early discharge of oversize and
grinding medium
– Removal of fines, prevents over-grinding
Grate Discharge
- Mixture of ore, water, and grinding media
Mill Charge
– Minerals are
susceptible to physical
and chemical changes
with water
Dry Grinding
– Lower kWh/Mt
– Higher Mt/m3 mill
volume
– Closer product control
by classification
– Elimination of dust
– Simpler handling;
pumps and launders
Wet Grinding
– Rolling motion of the charge down to the toe
– Leads to finer grinding by abrasion (↑liner
wear)
Cascading
– Parabolic path taken by charge as projected
by lifting of the mill
– Coarse grinding by impact (↓liner wear)
Cataracting
– Charge is carried around in a fixed position
Centrifuging
it is adjusted to control the
trajectory of the GM; to hit the ore, not the
mill liners!
Mill Speed
TM’s are normally operated bet. __% -
__% of critical speed
50-90%
- 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
cast iron rods daw oh
Rod Mills
- Rod Mills are practically always run in
______
in unsa?
Open Circuit
- 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)
forged steel balls daw oh
Ball Mill
Higher mill rotation speeds – ______ is
dominant
Cataracting
Ball Mills are often operated in _________ to minimize over-grinding
CLosed Circuit
- 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
- The main mechanism for grinding is by
by????
Abrasion
the size at w/c the particles
inside the AG is already too small for
efficient grinding
Critical Size
Useful Range of ELUTRIATION
AHAHHAHHAHAHHAHAHA
40-5
Useful Range of TEST SIEVES
AHHAHHAHAHHAAHHAH
100000 – 10
- Segregation of Materials into products
characterized by difference in size - Screening and Classification
Unit Operation in Mineral Processing
Sizing
Useful Range of SEDIMENTATION (CENTRIFUGE)
heheheh
5-0.05
Useful Range of MICROSCOPY
bleee
50 – 0.25
Useful Range of SEDIMENTATION (GRAVITY)
sge gow
40 – 1
Useful Range of ELECTRON MICROSCOPY
korek
1-0.005
- 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
COMPLICATION IN SIEVING
duha ni sila
-irregularly shaped particles
-near size particles “blinding”
*Designated by nominal aperture sizes
– Sides of square or diameter of circle aperture
* Mesh no. ≈ # of square apertures/inch2
test sieves
- 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
- Ro-tap
- topmost
- 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
STATIONARY SCREENS
(?)
– 20mm – 300mm, 1000tph max
– 20 – 500 deck angle
– Uses heavy parallel bars
Grizzly
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
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
MOVING SCREEN
(?)
– 250μm – 25cm
– Most important screens
– Multi-decks
Vibrating Screens
?
WHat is the basis for separation????
?
?
velocity of the particles as the grains fall through a fluid medium
shear forces between
medium and mineral surface
Viscous Resistance
due to displacement
of fluid by the mineral
Turbulent Resistance
– pt. of 0 acceleration
Gravity ≈ Resistant Forces
Terminal Velocity
- a system with a large volume of medium
relative to particles - No particle crowding (<15% solids w/w)
Free Settlings of Particles
- ↑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
(1)
- The case where there is an increase in
pulp density (>15% solids w/w) - ↑pulp density, ↑viscosity, resistance is
mainly due to (2)____
- Hindered Settling
- Turbulence
- 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
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
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
Mechanism for removal of coarse / dense
minerals is a rake system moving up an
incline
Rake Classifier
- Uses a continuous moving spiral to move
sands up a slope - May be used at steeper slopes (de-H2O)
Spiral/Screw Classifier
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
- Tangential
- Vortex
- Separation of valuable minerals
- Based on the physical characteristics of
minerals
Concentration
- Solid/liquid separation by thickeners
and filters
Dewatering
- Bins, conveyors, feeders, pumps, etc.
Auxiliary Operations
