Basdew Rooplal
Mining & Metallurgical Consultant
http://mineralprocessingconsultant.com/
PLANT DESIGN
CONSTRUCTION AND
OPE...
CONTENTS
Plant Design Construction
and Operation
 Bench scale and pilot scale design
for comminution circuits
 Factors i...
CONTENTS
Plant optimisation and
energy efficiency
considerations
• Characterisation –
Understanding the ore body
and the M...
BENCH SCALE AND PILOT SCALE
DESIGN FOR COMMINUTION
CIRCUITS
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BENCH SCALE TESTWORK
Introduction
• The resistance of ore samples
to breakage (or hardness) is
measured through grindabili...
SUMMARY OF
GRINDABILITY TESTS
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GRINDABILITY TESTS
Bond Ball mill
Grindability
• The AG/SAG mill or HPGR
circuit products, which have
non-standard particl...
GRINDABILITY TESTS
Bond Rod mill work
Index
• The rod mill work Index is
also normally distributed
with and average and
me...
GRINDABILITY TESTS
Bond low energy
impact test
• Consists of an apparatus with
two pendulum hammers
mounted on two bicycle...
GRINDABILITY TESTS
SAG power index (SPI)
• SPI expressed in minutes , is
the time T necessary to
reduce the ore from P80 o...
GRINDABILITY TESTS
JKTECH drop weight
test
• Developed by JKMRC
• Divided into 3 components:
• Test measures the resistanc...
GRINDABILITY TEST
JKTECH drop weight
test
• The test generates the
appearance function –
• E.g. the breakage pattern of
th...
GRINDABILITY TESTS
JKTECH Drop weight
test
• Also part of these procedure is
the density determination of
20 rock samples,...
GRINDABILITY TESTS
JKTECH drop weight
test
• A great number of rock
weight tests have been
performed over the years
which ...
GRINDABILITY TESTS
JKTECH drop weight
test
• One of the interesting
features of the drop weight
test procedure is that it
...
GRINDABILITY TESTS
SAG Mill
comminution test
• This is an abbreviated drop
weight test, which can be
performed at low cost...
GRINDABILITY TESTS
MacPherson Autogenous
Grindability tests
• This is a continuous test
performed in a 46 cm semi-
autogen...
GRINDABILITY TESTS
MacPhersons Autogenous
grinding tests
• Throughput rates • Specific Energy
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GRINDABILITY TEST
Media Competency
test
• There has been some
variations of media
competency test developed
over the years...
GRINDABILITY TESTS
High Pressure
Grinding Rolls
• HPGR are emerging as an
energy efficient alternative to
AG/SAG circuits....
CRUSHABILITY TEST
Impact Crushability
• Gives a WI that can be applied
to 3 types of crushers
• Gyratory – WI can be used ...
CRUSHABILITY TESTS
Paddle Abrasion
• Results are in the form of
Abrasion Index and chemical
makeup of the material
• Tests...
CRUSHABILITY TESTS
French Abrasion
• Gives an Abrasion and
Crushability Index
• Mainly used to estimate
hammer wear in the...
DISCUSSION POINTS!
• Where can I apply Bench
scale and pilot scale
programs in my work
environment?
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FACTORS INFLUENCING THE
SELECTION OF COMMINUTION
CIRCUITS
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FACTORS INFLUENCING THE
SELECTION OF
COMMINUTION CIRCUITS
• Geological Interpretation of
Drill core and Bulb Sample
• Mine...
FACTORS INFLUENCING THE
SELECTION OF
COMMINUTION CIRCUITS
• Circuit selection
• Metallurgical efficiency
• Cost Considerat...
GEOLOGICAL
INTERPRETATION OF DRILL
CORE AND BULK SAMPLE
Information Gained
• Identification and relative
abundance of Mine...
MINERALOGICAL ANALYSIS
Information Gained
• Identification of ore and
gangue minerals and
middling association
• Liberatio...
CHEMICAL ANALYSIS
Information Gained
• Identification of metallic ,
non-metallic and acid
generating constituents
Effect o...
PHYSICAL PROPERTIES
Information Gained
• Hardness, Blockiness,
Friability, Quantification of
primary fines and clay
conten...
CIRCUIT FEED PARAMETERS
Information Gained
• ROM top size parameters
• Primary crusher discharge
size analysis
• Throughpu...
SAMPLING REQUIREMENTS
Information Gained
• Preliminary drill core for
resource definition and split
for bond work indices
...
CONTIGUOUS PROPERTIES
Information Gained
• Definition of equipment
characteristics
Effect on Circuit
Selection
• Determine...
FEED AND PRODUCT
SPECIFICATION
Information Gained
• Definition of requirements
at each comminution stage
Effect on Circuit...
BOND WORK INDICES,
ABRASION INDEX, AND
SPECIFIC POWER
CONSUMPTIONS
Information Gained
• Calculation of specific power
cons...
CIRCUIT SELECTION
Information Gained
• Assessment of Overall Power
requirements and power
efficiency for different circuit...
METALLURGICAL EFFICIENCY
Information Gained
• Definition of Optimum
comminution configuration
• Definition of feed rate
va...
COST CONSIDERATION
Information Gained
• Definition of Largest
practical equipment size
and design
• Differences between
co...
WATER SUPPLY
Information Gained
• Definition of Process
alternatives
Effect on Circuit
Selection
• Determination of plant
...
FINE GRINDING
Information Gained
• Determination of test
requirements, batch and /
or Pilot scale tests
Effect on Circuit
...
PLANT LAYOUT
Information Gained
• Definition of Geographic
location, Climatic conditions,
Accessibility
• Definition of re...
DISCUSSION POINTS!
• Comments on pertinent
factors that was involved in
the selection of your plant
system.
• The pros and...
TYPES AND CHARACTERISATION OF
CRUSHER EQUIPMENT AND CIRCUIT
FLOWSHEET
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INTRODUCTION
Standard Equipment
• Crushing flowsheet and
equipment are selected to
prepare ore for downstream
purposes. St...
FACTORS AFFECTING
CRUSHER SELECTION
• Plant throughput, ore
delivery schedules
• Size of feed
• Desired product size for
d...
PLANT THROUGHPUT AND
ORE DELIVERY SCHEDULES
• Forms the base line for
flowsheet design and
equipment selection
• Size type...
FEED SIZE
• The crusher selected must
be sized for throughput as
well as top size expected
from the mine.
• Smaller the cr...
PRODUCT SIZE
• The target product size
required from the crushing
circuit will determine the
number of crushing stages and...
ORE CHARACTERISTICS
• When selecting equipment for
inclusion in a crushing
flowsheet the following factors
should be consi...
CLIMATIC CONDITIONS
• A dry warm climate will
allow for an unenclosed
installation.
• Colder wet climates will
require enc...
DOWNSTREAM
PROCESSES
• Heap Leaching
• Crusher product size will
be specified for optimum
recovery
• Milling
• Type of gri...
APPLICATION
Primary Crusher
• Purpose
• To reduce the ore to a size
amenable to secondary
crushing, SAG mill feed or
heap ...
APPLICATION
Secondary Crushers
• Purpose
• To produce an intermediate or
final product
• Feed Size – typically between
200...
APPLICATION
Tertiary Crushers
• Purpose: Produce the final
product
• Feed : 37 mm
• Product : 12 mm
• Crusher type:
• Shor...
APPLICATION
Quaternary Crushing
• Purpose:
• To produce fine dry product
for downstream processing
• Vertical Impact Crush...
CRUSHER TYPES
• Jaw
• Gyratory
• Horizontal shaft impact
crushers
• Rotary breakers
• Roll Crushers
• Cone crushers
• Gyra...
FLOWSHEET – TWO STAGE
CRUSHING (FINE PRODUCT)
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TWO STAGE CRUSHING
(COARSE PRODUCT)
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THREE STAGE CRUSHING
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THREE STAGE CRUSHING
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THREE STAGE CRUSHING
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TWO STAGE WITH WATER
FLUSH CRUSHER
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THREE STAGE CRUSHING –
GOLD HEAP LEACH
64
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THREE STAGE CRUSHING AND
WATER FLUSH CRUSHER
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WATER FLUSH CRUSHING
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SABC CONFIGURATION
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THREE STAGE CRUSHING
WITH VERTICAL SHAFT
IMPACTORS
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DISCUSSION POINTS!
• What are the Problem areas of current equipment
installation?
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SELECTION AND SIZING OF
PRIMARY CRUSHER
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INTRODUCTION
• The rock / ore determines
the type of crusher
• The plant capacity
determines the size of
crusher
Family of...
HISTORY
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MECHANICAL REDUCTION
METHODS
Four basic ways to
reduce a material
• Impact
• Attrition
• Shear
• Compression
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COMPRESSION
• Done between two surfaces
• Gyratory and double toggle
jaw uses this method
Should be used when
• Material i...
IMPACT
• Refers to sharp ,
instantaneous impingement
of one moving object
against another
• Two types
• Gravity
• Dynamic
...
ATTRITION
• Scrubbing material between
two hard surfaces
• Hammer mills operate with
close clearance between
hammers and s...
SHEAR
• Consists of trimming or
cleaving action
• Exploits the fact that the ratio
of compressive strength to
tensile and ...
PRIMARY GYRATORY
CRUSHERS
• The main capacity
advantage offered is
centred around the
Archimedes principal
• They found th...
GYRATORY CRUSHER
Advantages
• Designed for direct dump
from trucks Lowest
maintenance per ton
processed of any designed
cr...
JAW CRUSHER ANIMATION VIDEO 1
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WORKING PRINCIPLES OF THE JAW
CRUSHER VIDEO 2
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DOUBLE TOGGLE DESIGN
• The swing Jaw of the Standard
DT crusher pivots from an
overhead shaft .
• A Pitman hung from an
ec...
DOUBLE TOGGLE JAW
Advantages
• Lower installed cost than a
Gyratory crusher
• Can handle high abrasion
with low maintenanc...
SINGLE TOGGLE JAW
CRUSHER
• The rotation of the eccentric
shaft causes the swing Jaw
assembly to move in an
elliptical pat...
SINGLE TOGGLE JAW
CRUSHER
Advantages
• Lower installed cost than a
double toggle
• Lower power usage than a
double toggle
...
LOW SPEED SIZERS
• The low speed sizing
principle is the combination
of high torque / low roll
speeds.
• The interaction o...
LOW SPEED SIZERS
Advantages
• Can handle high tonnages – 12
000 MTPH
• Low installation cost and
minimum head room require...
SINGLE TOGGLE VS.
DOUBLE TOGGLE
• ST has a larger angle of nip,
the larger the nip angle the
harder to grip the material.....
IMPACT CRUSHERS
• Utilized in soft, non-
abrasive application
• Crushing availability and
maintenance can
economically off...
OPERATION OF AN IMPACT
CRUSHER VIDEO 3
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IMPACTOR ANIMATION VIDEO 4
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IMPACT CRUSHER
Advantages
• Can handle larger size
reduction 1000 : 75
• High reduction ratio
compared to investment
cost
...
FEEDER BREAKERS
• Are utilised in soft to
medium hard application
• Coarsely break material for
belt conveying
• Frequentl...
FEEDER BREAKER
Advantages
• Avoids costly site preparation
and civil work
• Can transfer and crush
material in a single ma...
PRIMARY CRUSHER
SELECTION CRITERIA
• Will it produce the desired
product size at required
capacity
• Will it accept the la...
PRIMARY CRUSHER
SELECTION CRITERIA
• Does the crusher operate
economically with
minimum maintenance
• Does the crusher hav...
PRIMARY CRUSHER
SELECTION - CAPACITY
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PRIMARY CRUSHER
SELECTION – FEED SIZE
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PRIMARY CRUSHER
SELECTION – PRODUCT SIZE
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PRIMARY CRUSHER
SELECTION – COMPRESSIVE
STRENGTH
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PRIMARY CRUSHER
SELECTION – ABRASION
INDEX
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PRIMARY CRUSHER
SELECTION – CLAY CONTENT
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PRIMARY CRUSHER
SELECTION – UNDERGROUND
APPLICATION
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PRIMARY CRUSHER
SELECTION – MOBILE PLANTS
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COMPUTER AIDED DESIGN OF JAW
CRUSHER
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COMPONENTS OF A JAW
CRUSHER
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MATERIAL FOR
COMPONENTS OF JAW
CRUSHER
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KINEMATIC ANALYSIS OF
JAW CRUSHER
• The geometry of the
moving Jaw results in a
movement change which
has a great effect o...
SWINGING JAW
MOVEMENT
• The reciprocating jaw MN
driven by the eccentric shaft
AB does kind of a periodic
plane swing move...
• MN is the moving jaw and
OM is the toggle bar.
• In the analysis we are
intended to find out the
displacement, velocity ...
DATA EXTRACTED FROM
STANDARD JAW CRUSHER
• Length AN = 172 cm
• Length MN = 1085 cm
• Length OM = 455 cm
• Co-ordinates of...
CRANK ANGLE VS. ANGLE
MADE BY MOVING JAW
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CRANK ANGLE VS. ANGLE
BETWEEN MOVING JAW AND
Y AXIS
• The graph shows as the
moving Jaw approached its
counterpart which i...
VERTICAL DISPLACEMENT VS.
HORIZONTAL DISPLACEMENT
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HORIZONTAL DISPLACEMENT
VS. CRANK ANGLE
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DISPLACEMENT VS. CRANK
ANGLE
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POINTS ON THE MOVING
JAW
• Every point on the moving
Jaw follows an elliptical
path
• When it moves towards the
fixed Jaw,...
VERTICAL VELOCITY VS.
CRANK ANGLE
• The rate of change of
vertical velocity is greater
for the topmost point and
decreases...
HORIZONTAL VELOCITY
VS. CRANK ANGLE
• The rate of change of
horizontal velocity is greater
for the bottom most point
and d...
VELOCITY VS. CRANK
ANGLE
• The maximum rate of
change of final velocity is
greater for the points away
from the crank.
htt...
HORIZONTAL ACCELERATION
VS. CRANK ANGLE
• With progress from 0 to 360
degrees crank angle
rotation the horizontal
accelera...
VERTICAL ACCELERATION VS.
CRANK ANGLE
• With progress from 0 to 360
degrees crank rotation the
vertical acceleration first...
ACCELERATION VS. CRANK
ANGLE
• The maximum acceleration
is observed for the points
farthest away from the
crank angle
http...
EFFECT OF SLIDING
MOTION ON JAW WEAR
• Breakage Analysis
• 3 types of Fracture
mechanisms are observed
• Abrasion
• Cleava...
BREAKAGE ANALYSIS
• The particle fracture
mechanism in the Jaw
crusher chamber is a
mixture of cleavage and
abrasion. The ...
CRUSHING PROCESS
• Theoretically a particle
inside the crusher is crushed
when it is compressed and
fails in tensile stres...
CRUSHING PROCESS
• As the horizontal and
vertical velocities of the
moving jaw changes during
the crushing process, the
fo...
CRUSHING PROCESS
• When the component of the
vertical velocity is less than
the components of the
horizontal velocity the
...
CRUSHING PROCESS
• By a resolution of forces
acting on the particle as
shown in figure 3.3. it can
be proved that conditio...
WEAR ANALYSIS
• Squeezing and sliding are the
two principal factors affecting
the Jaw plates wear
• Squeezing plays the ma...
DISCUSSION POINTS!
• What are the flaws of the
current primary crusher
installation?
• Where can we improve?
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SELECTION AND SIZING OF
SECONDARY AND TERTIARY
CRUSHERS
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INTRODUCTION
• Modern crushers have
increased in performance
• Evolved to focus greater on
the quality of desired
product
...
HOW THE SYMONS CONE CRUSHER
WORKS VIDEO 5
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NEW GENERATION OF CONE
CRUSHERS VIDEO 6
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CONE CRUSHERS
Modern Cone
crushers
• Increased performance
capabilities
• More power capabilities
• Larger in size
• Highe...
NEW CONE CRUSHERS
• New generation of cone
crushers provide
• ease of operation
• Simple maintenance
• Uniform production
...
CONE CRUSHER
SELECTION CRITERIA
Information required
• Capacity required with
consideration for expected
availability
• Ex...
CONE CRUSHER DESIGN
LIMITS
Design limits
• Volume limits
• Power limits
• Force Limits
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DESIGN LIMITS - VOLUME
• Maximum rate of feed to
the cone crusher without
overfilling the cone crusher
feed hopper
• Funct...
DESIGN LIMIT - POWER
• Power limit is reached when
average power draw kW
exceeds the installed motor
power of the crusher....
DESIGN LIMIT – FORCE
FACTOR
• The force limit of a crusher
is reached when the
combined forces exerted
during crushing exc...
CONE CRUSHER SIZES AND
CAPACITY RANGES
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SECONDARY CONE
CRUSHER SELECTION
• Ensure the feed material
does not exceed the
acceptable maximum size
for the crusher
• ...
SECONDARY CONE
CRUSHER SELECTION
Correct cavity
configuration
• The cavity configuration has to
suit the feed gradation so...
CASE STUDY: HP700
REPLACING HAMMER MILL
Copper mine in
Portland
• Hammer mill used to
prepare rod mill feed
• Hammer mill ...
CASE STUDY: HP700
REPLACING HAMMER MILL
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CASE STUDY: HP700
REPLACING HAMMER MILL
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THE PRE-CRUSHER
OPTION
• The most recent evolution for
pebble crushing finds a basis
in the presumption that the
most appr...
CASE STUDY: PRE-
CRUSHING
Troilus Mine
• 150 – 50 mm is pre-crushed
using an HP 700 cone
crusher
• Production increase and...
TYPICAL PRE-CRUSHER
INSTALLATION
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TRACK MOUNTED CONE CRUSHER
VIDEO 7
152
Selectionandsizingof
Secondaryantertiarycrushers
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CASE STUDY : INFLUENCE OF
ECCENTRIC SPEED OF CONE
CRUSHER PRODUCTION AND
OPERATION
153
Selectionandsizingof
Secondaryanter...
CASE STUDY : PILOT TEST
PROGRAM
• The research was performed in
Tampere, Finland using an HP
200 cone crusher
• The study ...
CASE STUDY : PILOT TEST
PROGRAM
• A third set of tests utilized a
different feed size in order
to verify results as well a...
CASE STUDY: PILOT TEST
RESULTS
Overall
• Most of the data showed
clear trends in capacity,
power and discharge size
distri...
CASE STUDY : BASE
TESTING RESULTS
• On average, the total
capacity tph fluctuated by
22.5% over a design speed
range of 34...
CASE STUDY: BASE
TESTING RESULTS
• For a base case testing with
a full cavity throughout, it
was seen that there was
sligh...
CASE STUDY: 32 MM CSS
PRODUCTION VS. SPECIFIC
ENERGY
159
Selectionandsizingof
Secondaryantertiarycrushers
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CASE STUDY : 19 MM CSS
PRODUCTION VS. SPECIFIC
ENERGY
160
Selectionandsizingof
Secondaryantertiarycrushers
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CASE STUDY: FIXED
TONNAGE TEST RESULTS
• The tests operated at a fixed
tonnage were conducted to
simulate a crushing appli...
CASE STUDY: FIXED
TONNAGE TEST RESULTS
• The tph of the -12.5 mm
product fell slightly as the
eccentric speed reduced
from...
CASE STUDY : FIXED
TONNAGE TEST RESULTS
• For the fixed tonnage tests
there was a marked
improvement in the
variation of p...
CASE STUDY : PRACTICAL
APPLICATION
• There are a number of uses for these
principles in a crushing plant. The
main points ...
CASE STUDY : PRACTICAL
APPLICATION
• A dynamic control system
can be used to vary the
speed resulting in benefits
to produ...
DISCUSSION POINTS!
• Choke feeding in your
current application, the pros
and cons.
166
Selectionandsizingof
Secondaryanter...
SELECTION AND SIZING OF HIGH
PRESSURE GRINDING ROLL
CRUSHERS
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NEW CRUSHERS ON THE MARKET
VIDEO 8
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HPGR INTRODUCTION
• HPGR are well established
in the cement industry for
the grinding of clinker,
limestone, slag and othe...
HPGR INTRODUCTION
• Moisture content up to 12
%
• Machines are available with
capacities up to 3000 tph
• Installed power ...
HPGR INSTALLED IN
DIAMOND AND IRON ORE
INDUSTRIES
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HPGR – L/D RATIOS
Length to Diameter
ratio
• Is it more advantageous to
design rolls with smaller
diameters and larger wid...
HPGR – L/D RATIO
• The decision as to which
approach to adopt is
capital.
• It has an impact not only on
the performance o...
HPGR – L/D RATIO
• The size of the bearing
determines the shaft
diameter and pre-
determines the manner in
which the gear ...
HPGR – ROLL DESIGN
• Three different roll designs
have been successfully
applied:
• Solid rolls
• Rolls with tyres
• Rolls...
HPGR – CRITERIA FOR
SELECTING OPTIMUM DESIGN
• The balance between
operating and investment
cost
• The acceptable lifetime...
HPGR - COMPARISON
Tyres
• Lower investment cost
• No interfaces (joints)
• Longer lifetime
• Lower wear cost
• No pressure...
HPGR - WEAR
PROTECTION SURFACES
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HPGR - WEAR PROTECTION
OF ROLL SURFACES
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HPGR – KEY PARAMETERS
• Achieve the throughput
requirements and to
achieve the desired product
fineness
Throughput
• Funct...
HPGR – KEY PARAMETERS
Product Fineness
• Controlled by the grinding
force applied to the
material bed between the
rolls.
•...
HPGR – THROUGHPUT
RATE VS. ROLL SPEED
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HPGR – FEED MOISTURE
CONTENT VS. THROUGHPUT
RATE
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HPGR – THROUGHPUT VS.
SIZE DISTRIBUTION
184
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HPGR – PRODUCT
FINENESS
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HPGR – PRODUCT OF
VARIOUS ORES
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HPGR – ENERGY
CONSUMPTION VS. FORCE
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HPGR – ENERGY INPUT VS.
ROLL SURFACE
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HPGR - ENERGY INPUT
FOR VARIOUS ORES
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HPGR – ENERGY INPUT VS.
GRINDING FORCE
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HPGR WEAR FACTORS
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HPGR – ROLL DIAMETER
VS. ROLL SPEED
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HPGR - APPLICATION
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HPGR – PEBBLE CRUSHER
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HPGR – PRE-CRUSHER
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HPGR – REPLACEMENT OF
3RD AND 4TH STAGE
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DISCUSSION POINTS!
• Is it possible to include
HPGR in your circuit?
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ORE CHARACTERISATION
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CHARACTERISATION -
UNDERSTANDING THE ORE
BODY AND THE METALLURGY
• The best possible
characterisation of the ore
body will...
CHARACTERISATION -
UNDERSTANDING THE ORE
BODY AND THE METALLURGY
• At its simplest ,
characterisation is about
developing ...
CHARACTERISATION -
UNDERSTANDING THE ORE
BODY AND THE METALLURGY
• An image analysis system
was used to provide an
estimat...
CHARACTERISATION -
UNDERSTANDING THE ORE
BODY AND THE METALLURGY
Rock Mass Properties
• Standard rock mass
properties are ...
CHARACTERISATION -
UNDERSTANDING THE ORE
BODY AND THE METALLURGY
Metallurgical Process
Parameters
• These data typically i...
CHARACTERISATION -
UNDERSTANDING THE ORE
BODY AND THE METALLURGY
Predictive Models
• Models frequently used in
mine to mil...
CHARACTERISATION -
UNDERSTANDING THE ORE
BODY AND THE METALLURGY
Conclusions
• The literature analysis suggests
that the t...
CASE STUDY: ANTAMINA BOOSTS
THROUGHPUT FOR HARD ORES
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CASE STUDY: ANTAMINA
BOOSTS THROUGHPUT FOR
HARD ORES
Introduction
• The ore body that
Compania Minera Antamina
has been mi...
CASE STUDY: ANTAMINA
BOOSTS THROUGHPUT FOR
HARD ORES
• The team began by auditing
the drill and blast practice as
well as ...
CASE STUDY: ANTAMINA
BOOSTS THROUGHPUT FOR
HARD ORES
• The ore was categorised in
varying groups of hardness.
• Blast prac...
CASE STUDY: ANTAMINA
BOOSTS THROUGHPUT FOR
HARD ORES
• In the drilling process the
drill pattern ( burden and
spacing) was...
CASE STUDY: ANTAMINA
BOOSTS THROUGHPUT FOR
HARD ORES
Conclusion
• Mine to mill optimisation work
increased throughput by 3...
CASE STUDY : BATU HIJAU
(INDONESIA)
PRODUCTION PLANNING FOR THE
COMBINED MINE TO MILL
OPERATION
212http://mineralprocessin...
CASE STUDY:
INTRODUCTION
• The Batu Hijau copper –
gold operation commenced
a mine to mill program in
2001 with the standa...
CASE STUDY BATU HIJAU
• Using rock mass
characterisation data, ore
hardness and blast design
data, simple regression
model...
CASE STUDY : BATU HIJAU
• Attention then turned to
developing the best
blasting practice for the
domains to reduce
fragmen...
CASE STUDY : BATU HIJAU
• The second phase of the
study was based on
improving prediction of mill
throughput based on
impr...
CASE STUDY : BATU HIJAU
• In 2007 the equations
linking mill throughput to
measurable variables were
coded into the mine b...
CASE STUDY : BATU HIJAU
Outcomes first phase
• Productivity gains of 10%
for loading rates in the pit
and 10-15% increases...
CASE STUDY : BATU HIJAU
Outcome first phase
• Accurate models of blasting
and comminution to
establish expected
performanc...
CASE STUDY : BATU HIJAU
Outcome second
phase
• The second phase of the Batu
Hijau study provides the basis
for a much wide...
CASE STUDY : BATU HIJAU
• The applications of that
capability include:
• The understanding of the
expected or benchmark
pe...
ORE DRESSING STUDIES – WHAT
IS INVOLVED
222http://mineralprocessingconsultant.com/
ODS - WHAT IS INVOLVED
Introduction
• Ore dressing studies the
characterisation of the ore
body with respect to
metallurgi...
ODS - KNOWLEDGE FLOW224
http://mineralprocessingconsultant.com/
ODS - IN AN ORE BODY
DEVELOPMENT
225
http://mineralprocessingconsultant.com/
ODS - GENERIC DIAGRAM
FOR SAMPLE
CHARACTERISATION
226
http://mineralprocessingconsultant.com/
ODS - COMMINUTION
CHARACTERISATION
• Test work consists of a suit of
laboratory and pilot plant scale
tests
• Laboratory t...
ODS - COMMINUTION
CHARACTERISATION
• Depending on the
requirement of the specific
ore dressing study, i.e.
feasibility stu...
ODS - DATA ANALYSIS
AND INTERPRETATION
• The data generated from the
characterisation tests is
analysed and interpreted by...
ODS - DATA ANALYSIS
AND INTERPRETATION
• The output results in key
plant design information.
• E.g. comminution
characteri...
ODS - INTEGRATION
• The role of the metallurgist is
key in generating the
flowsheet design knowledge
package through the
i...
ODS - INTEGRATION
• Simulation enables critical
investigation of all system
attributes, and the ability of
the circuit des...
ODS - PLANT DESIGN
• To reduce the risk of selecting
incorrect equipment from a
vast array of possibilities a
formalised s...
ODS - PLANT DESIGN
• Completed ore dressing
study assists the process
engineer to rapidly evaluate
scenarios using existin...
PROFIT BASED GRINDING
CONTROLS
Case Study : Sierrita
Program controller : Duval Corporation
235http://mineralprocessingcon...
CASE STUDY : SIERRITA
Introduction
• The comminution circuit
represents the largest user
of energy in the Mineral
Processi...
CASE STUDY : SIERRITA
Description of the
Plant
• Wet grinding circuit treats
90 000 stpd
• Sixteen x Allis-Chalmers
overfl...
CASE STUDY : SIERRITA
Instrumentation
• Variable feeder
• Feeder Weight
measurement system
• Feed water flow meter
• Sump ...
CASE STUDY : SIERRITA
Process Analysis study
• Fig. 2 shows a schematic
diagram of a ball mill /
cyclone control system
• ...
CASE STUDY : SIERRITA
Objectives
• Reduction of mill feed size
• Reduction of mill power
consumption
• Extending mill tran...
CASE STUDY : SIERRITA
Disturbances
• Mill feed particle size
distribution due to bin
segregation and crusher
circuit opera...
CASE STUDY : SIERRITA
Design of the plant
control strategy
• Fig. 3 shows that for a given
ore there is a unique milling
r...
CASE STUDY : SIERRITA
Design of plant
control strategy
• Fig. 4 shows the control
objectives and limiting
conditions that ...
CASE STUDY : SIERRITA
Design of plant
control strategy
• The grind cut inferential
controller maintains the
optimal libera...
CASE STUDY : SIERRITA
Grinding controls
• The primary objective of the
grinding controls system is to
provide a flexible ,...
CASE STUDY : SIERRITA
Grinding controls
Simplified function
block control strategy
http://mineralprocessingconsultant.com/...
CASE STUDY : SIERRITA
The four principle
controllers
• The ball mill load control
system
• The grind index control
strateg...
CASE STUDY : SIERRITA
The ball mill load
controller
• This is the main controller
• Any additional capacity of
the ball mi...
CASE STUDY : SIERRITA
Control Design
http://mineralprocessingconsultant.com/
249
CASE STUDY : SIERRITA
MAIN CONTROLLER
WINDOW DISPLAY
http://mineralprocessingconsultant.com/
250
CASE STUDY : SIERRITA
Computer Architecture
for plant management
http://mineralprocessingconsultant.com/
251
CASE STUDY : SIERRITA
Overall plant control
strategy
• The current objective of
increasing the recovery / profit
by runnin...
CASE STUDY : SIERRITA
Conclusions
• A profitability concept was
transformed into a feasible
mode of operation.
• The tonna...
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Mineral Processing - Crushing - Plant design, construction, operation and optimisation

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Bench scale and pilot scale design for comminution circuits
Factors influencing the selection of comminution circuits
Types and characterisation of crusher equipment and circuit flowsheet
Selection and sizing of primary crusher
Computer aided design of Jaw Crusher
Selection and sizing of secondary and tertiary crushers
Optimising the Eccentric speed of cone crusher

Selection and sizing of High pressure roll crushers
Characterisation – Understanding the ore body and the Metallurgy
Ore dressing studies – what is involved.
Blasting for improved mining and comminution productivity
Production planning for the combined mine and comminution operation
Profit based comminution controls
Increasing the energy efficiency of Processing

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  • Figure 1 Two stage crushing (Fine Product)
    Figure 2: Two stage crushing (coarse product)
    Figure 3: Three stage crushing
  • Mineral Processing - Crushing - Plant design, construction, operation and optimisation

    1. 1. Basdew Rooplal Mining & Metallurgical Consultant http://mineralprocessingconsultant.com/ PLANT DESIGN CONSTRUCTION AND OPERATION PLANT OPTIMISATION AND ENERGY EFFICIENCY CONSIDERATIONS
    2. 2. CONTENTS Plant Design Construction and Operation  Bench scale and pilot scale design for comminution circuits  Factors influencing the selection of comminution circuits  Types and characterisation of crusher equipment and circuit flowsheet  Selection and sizing of primary crusher o Computer aided design of Jaw Crusher  Selection and sizing of secondary and tertiary crushers o Optimising the Eccentric speed of cone crusher  Selection and sizing of High pressure roll crushers  Advancement in Screening Technology. http://mineralprocessingconsultant.com/ 2
    3. 3. CONTENTS Plant optimisation and energy efficiency considerations • Characterisation – Understanding the ore body and the Metallurgy • Ore dressing studies – what is involved. • Blasting for improved mining and comminution productivity • Production planning for the combined mine and comminution operation • Optimising lumps to fines ratio in Iron Ore processing • Reducing fines generation in Coal Mining • Profit based comminution controls • Increasing the energy efficiency of Processing http://mineralprocessingconsultant.com/ 3
    4. 4. BENCH SCALE AND PILOT SCALE DESIGN FOR COMMINUTION CIRCUITS 4http://mineralprocessingconsultant.com/
    5. 5. BENCH SCALE TESTWORK Introduction • The resistance of ore samples to breakage (or hardness) is measured through grindability tests. • Several grindability tests have been developed over the years for different applications and each test has its own strengths and weaknesses • Grindability tests are a compromise between test costs and its deliverables. • The highest degree of deliverables and certainty is achieved in a pilot plant, which is also the most reliable test procedure to determine the resistance of ore samples to grinding or hardness and is also the most expensive. http://mineralprocessingconsultant.com/ 5
    6. 6. SUMMARY OF GRINDABILITY TESTS http://mineralprocessingconsultant.com/ 6
    7. 7. GRINDABILITY TESTS Bond Ball mill Grindability • The AG/SAG mill or HPGR circuit products, which have non-standard particle size distribution. • One of the keys of the Bond work index success over time has been its reliability and reproducibility. • The figure below shows that the Ball Mill work index is normally distributed with AVG 14.6 and Median 14.8 http://mineralprocessingconsultant.com/ 7
    8. 8. GRINDABILITY TESTS Bond Rod mill work Index • The rod mill work Index is also normally distributed with and average and median of 14.8kWh/t • It is common to observe difference between the ball and rod mill caused by variation in ore hardness • The test has been mainly used for the design of rod mill or primary ball mills. http://mineralprocessingconsultant.com/ 8
    9. 9. GRINDABILITY TESTS Bond low energy impact test • Consists of an apparatus with two pendulum hammers mounted on two bicycle wheels, so as to strike equal blows simultaneously on opposite sides of each rock specimen. • The height of the pendulum is raised until the energy is sufficient to break the rock specimen • The test is generally performed on 20 rocks • One of the strengths of the test is to measure the natural dispersion in the sample. • Another advantage of the test is the coarse size 2 – 3 inches which makes it unique in the series of tests. http://mineralprocessingconsultant.com/ 9
    10. 10. GRINDABILITY TESTS SAG power index (SPI) • SPI expressed in minutes , is the time T necessary to reduce the ore from P80 of 12.5mm to P80 of 1.7 mm • The SPI has the advantage of requiring low weight and is suited for geometallurgical mapping of ore deposits • SPI is widely used and deposits can be compared in terms of hardness and variability, see fig below. http://mineralprocessingconsultant.com/ 10
    11. 11. GRINDABILITY TESTS JKTECH drop weight test • Developed by JKMRC • Divided into 3 components: • Test measures the resistance to impact breakage of coarse particles in the range 63 – 13.2 mm • Then evaluates the resistance to abrasion breakage in the range 53 – 37.5 mm • Finally the rock density of 20 particles is measured to asses the average ore density as well as its dispersion. http://mineralprocessingconsultant.com/ 11
    12. 12. GRINDABILITY TEST JKTECH drop weight test • The test generates the appearance function – • E.g. the breakage pattern of the ore under a range of impact and abrasion breakage conditions • The appearance function can be used in the JKSimMet modelling and simulation package to predict the ore response to comminution process http://mineralprocessingconsultant.com/ 12
    13. 13. GRINDABILITY TESTS JKTECH Drop weight test • Also part of these procedure is the density determination of 20 rock samples, using water displacement techniques. • Figure 5 shows an ore displaying a wide range of densities. • The density distribution of the ore is important in AG/SAG milling because • It affects the bulk density of the charge and associated power draw http://mineralprocessingconsultant.com/ 13
    14. 14. GRINDABILITY TESTS JKTECH drop weight test • A great number of rock weight tests have been performed over the years which allows for comparison of ore types in a data base. • The frequency distribution of the function ‘A x b’ from JKTech is depicted in Fig 6 http://mineralprocessingconsultant.com/ 14
    15. 15. GRINDABILITY TESTS JKTECH drop weight test • One of the interesting features of the drop weight test procedure is that it provides a variation in rock hardness by size from 13.2 to 63 mm. • Fig 7 illustrates this at 3 different energy levels. • 0.25 1.0 and 2.5 kWh/t • For a very competent ore, the curve will be nearly horizontal, a non- competent fractured ore will show a high gradient with increasing size http://mineralprocessingconsultant.com/ 15
    16. 16. GRINDABILITY TESTS SAG Mill comminution test • This is an abbreviated drop weight test, which can be performed at low cost on small samples 19 – 22 mm or drill cores. • 5 kg of sample is normally sufficient. • The advantage of the SMC test is that it generates the energy versus breakage relationship with as small quantity of sample of a single size fraction. • Because the test can be performed on small rocks, it is well suited for geometallurgical mapping. http://mineralprocessingconsultant.com/ 16
    17. 17. GRINDABILITY TESTS MacPherson Autogenous Grindability tests • This is a continuous test performed in a 46 cm semi- autogenous mill with an 8% ball charge. • The pilot plant consists of a feed hopper, cyclone, screen and dust collector with a control system to regulate the charge volume and circulating load. • 100 to 175 kg of sample is required with a top size greater than 25 mm. • The test is run continuously for 6 hours. • The importance of reaching a steady state in a grinding mill is widely accepted, this test is the only small scale test that offers the option. http://mineralprocessingconsultant.com/ 17
    18. 18. GRINDABILITY TESTS MacPhersons Autogenous grinding tests • Throughput rates • Specific Energy http://mineralprocessingconsultant.com/ 18
    19. 19. GRINDABILITY TEST Media Competency test • There has been some variations of media competency test developed over the years with the assessment of media survival in autogenous milling being the main objective. • 104 to 165 mm rocks are subjected to a tumble test using 10 large rock in 5 size fractions. • The surviving rocks are submitted to fracture energy test procedure. • This provides the relationship between the first fracture energy requirement and rock size. http://mineralprocessingconsultant.com/ 19
    20. 20. GRINDABILITY TESTS High Pressure Grinding Rolls • HPGR are emerging as an energy efficient alternative to AG/SAG circuits. • The traditional method for testing is processing large samples in a pilot scale. • Several tests are performed to asses the effect of operating pressure and moisture content on HPGR performance • The power input is recorded and presented below. http://mineralprocessingconsultant.com/ 20
    21. 21. CRUSHABILITY TEST Impact Crushability • Gives a WI that can be applied to 3 types of crushers • Gyratory – WI can be used to determine the horse power. • Impactors – WI is an indication of hardness • Cone Crusher – rate the material to determine the duty of the crusher http://mineralprocessingconsultant.com/ 21
    22. 22. CRUSHABILITY TESTS Paddle Abrasion • Results are in the form of Abrasion Index and chemical makeup of the material • Tests are used to determine whether an Impactor or cone crusher is suitable. • Can also be used to calculate the approximate liner life for the crusher http://mineralprocessingconsultant.com/ 22
    23. 23. CRUSHABILITY TESTS French Abrasion • Gives an Abrasion and Crushability Index • Mainly used to estimate hammer wear in the Impactor application Dynamic Fragmentation • Conducted for Impactor application • Measures the friability of the material • Dynamic fragmentation number will indicate if the Impactor is feasible for a particular application. http://mineralprocessingconsultant.com/ 23
    24. 24. DISCUSSION POINTS! • Where can I apply Bench scale and pilot scale programs in my work environment? http://mineralprocessingconsultant.com/ 24
    25. 25. FACTORS INFLUENCING THE SELECTION OF COMMINUTION CIRCUITS 25http://mineralprocessingconsultant.com/
    26. 26. FACTORS INFLUENCING THE SELECTION OF COMMINUTION CIRCUITS • Geological Interpretation of Drill core and Bulb Sample • Mineralogical Analysis • Chemical Analysis • Physical Properties • Circuit feed Parameters • Sampling requirements • Contiguous properties • Feed and product Specification • Bond work Indices, Abrasion Index, and specific power consumptions http://mineralprocessingconsultant.com/ 26
    27. 27. FACTORS INFLUENCING THE SELECTION OF COMMINUTION CIRCUITS • Circuit selection • Metallurgical efficiency • Cost Consideration • Water supply • Fine Grinding • Plant layout http://mineralprocessingconsultant.com/ 27
    28. 28. GEOLOGICAL INTERPRETATION OF DRILL CORE AND BULK SAMPLE Information Gained • Identification and relative abundance of Mineral content • Degree of Dissemination • Type of Lithology • Types of Alteration • Degree of Oxidation • Geotechnical Competence • Hardness Effect on Circuit Selection • Provides a guide to the types of circuit required and the types of samples required based on precedent • Determines the necessity of separate plants to process sulphide ores • Provides a guide to the selection of autogenous grinding http://mineralprocessingconsultant.com/ 28
    29. 29. MINERALOGICAL ANALYSIS Information Gained • Identification of ore and gangue minerals and middling association • Liberation and Modal Analysis • Quantitative analysis – QemScan Effect on Circuit Selection • Determine Ratios of reduction • Feed and product size analysis in primary , secondary and regrind circuits http://mineralprocessingconsultant.com/ 29
    30. 30. CHEMICAL ANALYSIS Information Gained • Identification of metallic , non-metallic and acid generating constituents Effect on Circuit Selection • Determining the requirements of pre- washing the ore http://mineralprocessingconsultant.com/ 30
    31. 31. PHYSICAL PROPERTIES Information Gained • Hardness, Blockiness, Friability, Quantification of primary fines and clay content • Specific gravity of mineral constituents Effect on Circuit Selection • Provides a guide to potential problems in Crushing Screening and Grinding the ore with respect to equipment selection and Over grinding and avoidance of slimes generation with respect to softer minerals. http://mineralprocessingconsultant.com/ 31
    32. 32. CIRCUIT FEED PARAMETERS Information Gained • ROM top size parameters • Primary crusher discharge size analysis • Throughput requirements and schedules • Mining Plans , Schedules, methods and equipment sizes Effect on Circuit Selection • Determines selection of primary crushers and necessity for pre-crushing can influence this selection by determination of the product size at the required throughput rate. http://mineralprocessingconsultant.com/ 32
    33. 33. SAMPLING REQUIREMENTS Information Gained • Preliminary drill core for resource definition and split for bond work indices • Whole core for Autogenous Media Competency Index, Impact crusher work indices and fracture frequency • Bulk Sample , large diameter drill core, open pit or underground for pilot plant testing Effect on Circuit Selection • Preliminary Assessment of grinding requirements and ore variability • Power based methods for mill sizing using results from Bond , Impact and grinding work indices • Assist in definition of Pilot plant test program and ore Variability Characteristics http://mineralprocessingconsultant.com/ 33
    34. 34. CONTIGUOUS PROPERTIES Information Gained • Definition of equipment characteristics Effect on Circuit Selection • Determines the utility of equipment with respect to its Inherent operating behaviour, e.g. Autogenous grinding mills grinding to a natural grain size, SAG mills breaking across grain boundaries and rod mill minimizing the creation of fines http://mineralprocessingconsultant.com/ 34
    35. 35. FEED AND PRODUCT SPECIFICATION Information Gained • Definition of requirements at each comminution stage Effect on Circuit Selection • Influence of “Mine to Mill” and choke feeding the primary crusher on subsequent stages Performance • Maximum feed top size in relation to high aspect and low aspect primary mills • Use of HPGR http://mineralprocessingconsultant.com/ 35
    36. 36. BOND WORK INDICES, ABRASION INDEX, AND SPECIFIC POWER CONSUMPTIONS Information Gained • Calculation of specific power consumption at each comminution stage for different ore types and composites. • Assessment of ore variability • Checking on pilot plant test data • Assessment of risk or contingency based on samples selected according to the mine plan Effect on Circuit Selection • Distribution of power Confirmation of specific power consumption and contingencies for Process design criteria • Calculation of estimates for media and liner wear. • Estimation of mill power requirements and distribution of power between equipment http://mineralprocessingconsultant.com/ 36
    37. 37. CIRCUIT SELECTION Information Gained • Assessment of Overall Power requirements and power efficiency for different circuit options • Assessment of Overall Operating Availability for different circuit options • Determination of unit power cost and demand for different circuit options Effect on Circuit Selection • Determination of the Most economic option on the basis of NPV of Capital and Operating cost and circuit availability for a fixed revenue rate. • Power efficiency should be optimised in design for each circuit option considered. http://mineralprocessingconsultant.com/ 37
    38. 38. METALLURGICAL EFFICIENCY Information Gained • Definition of Optimum comminution configuration • Definition of feed rate variation • Selection of grinding media Effect on Circuit Selection • Determination of necessity for stage grinding and stage concentration to optimise mineral liberation and recovery. • Quantify the effect of feed rate variations on the metallurgical efficiency of down stream processes. http://mineralprocessingconsultant.com/ 38
    39. 39. COST CONSIDERATION Information Gained • Definition of Largest practical equipment size and design • Differences between comminution options Effect on Circuit Selection • Effect of efficiency on crushing and grinding equipment E.g. Separation of screening plant from crushing plant. • Feed arrangement requirements • Choke feeding crushers http://mineralprocessingconsultant.com/ 39
    40. 40. WATER SUPPLY Information Gained • Definition of Process alternatives Effect on Circuit Selection • Determination of plant location Namely, Mine location, Applicability of dry grinding, Pre-concentration and use of sea water. http://mineralprocessingconsultant.com/ 40
    41. 41. FINE GRINDING Information Gained • Determination of test requirements, batch and / or Pilot scale tests Effect on Circuit Selection • Determination of Optimum location of Fine grinding application within the circuit and definition of the types of machines used. http://mineralprocessingconsultant.com/ 41
    42. 42. PLANT LAYOUT Information Gained • Definition of Geographic location, Climatic conditions, Accessibility • Definition of relative location of Mine vs. Plant • Definition of Operating schedules and manpower requirements • Definition of expansion potential Effect on Circuit Selection • Determination of wet and dry processes • Determination of Physical sizes of equipment and foot print of the plant • Determination of built-in contingencies that allow for future expansion • Consideration for the addition of equipment lines in the case of larger plants. http://mineralprocessingconsultant.com/ 42
    43. 43. DISCUSSION POINTS! • Comments on pertinent factors that was involved in the selection of your plant system. • The pros and cons of the current system, bottle necks, etc. http://mineralprocessingconsultant.com/ 43
    44. 44. TYPES AND CHARACTERISATION OF CRUSHER EQUIPMENT AND CIRCUIT FLOWSHEET 44http://mineralprocessingconsultant.com/
    45. 45. INTRODUCTION Standard Equipment • Crushing flowsheet and equipment are selected to prepare ore for downstream purposes. Standard equipment for the minerals industry has been : Jaw crushers Gyratory crushers Cone crushers New Equipment Water flush cone crushers Vertical and horizontal impactors High pressure grinding rolls http://mineralprocessingconsultant.com/ 45
    46. 46. FACTORS AFFECTING CRUSHER SELECTION • Plant throughput, ore delivery schedules • Size of feed • Desired product size for down stream processing Ore characteristics: Hard rock Clay Gravel Variability Climatic conditions Down stream processes http://mineralprocessingconsultant.com/ 46
    47. 47. PLANT THROUGHPUT AND ORE DELIVERY SCHEDULES • Forms the base line for flowsheet design and equipment selection • Size type, number of stages and number of crushers per stage for an application can be identified. • E.g. A primary Jaw crusher will be better suited for a conventional underground mining operation because: Tonnages are typically lower Feed material size is smaller Less headroom and a smaller excavation is required. http://mineralprocessingconsultant.com/ 47
    48. 48. FEED SIZE • The crusher selected must be sized for throughput as well as top size expected from the mine. • Smaller the crusher the smaller the dimension of the feed material that can enter the crusher chamber. • A balance between the plant capacity and the size of the crusher must be reached. • In multi stage crushing circuits the products of the preceding stage will be the determining factor in the selection of the size of the crusher and the crusher liner configuration. http://mineralprocessingconsultant.com/ 48
    49. 49. PRODUCT SIZE • The target product size required from the crushing circuit will determine the number of crushing stages and types of crushers to be used for a specific application. • E.g.. To produce a coarse product a single stage crusher may be required. • To produce a 15 mm product a two stage crushing may be required. • The ability to crush finer has been required for specific application. • For fine product sizes in dry process application flowsheet have incorporated vertical shaft impact crushers operated in closed circuit with vibrating screens. http://mineralprocessingconsultant.com/ 49
    50. 50. ORE CHARACTERISTICS • When selecting equipment for inclusion in a crushing flowsheet the following factors should be considered: • Hardness • Toughness • Abrasiveness • Moisture content • mineralisation • Geologists should provide info with regards to: • Rock types • Abundance of various rock types LOM • Short and long term delivery schedules should then be provided mining to adapt circuit configuration for LOM 50 http://mineralprocessingconsultant.com/
    51. 51. CLIMATIC CONDITIONS • A dry warm climate will allow for an unenclosed installation. • Colder wet climates will require enclosures for operator protection and moisture problems. • An enclosed crushing plant also posed dust extraction challenges. http://mineralprocessingconsultant.com/ 51
    52. 52. DOWNSTREAM PROCESSES • Heap Leaching • Crusher product size will be specified for optimum recovery • Milling • Type of grinding circuit will influence the number of crushing stages. http://mineralprocessingconsultant.com/ 52
    53. 53. APPLICATION Primary Crusher • Purpose • To reduce the ore to a size amenable to secondary crushing, SAG mill feed or heap leach product • Usually operated in open circuit. • Typical crushers used are • Jaw • Gyratory • Horizontal impactors • Rotary breakers • Ratio of reduction 8:1 • Some form of scalping screen may be installed in the case of Jaw and Impact crushers http://mineralprocessingconsultant.com/ 53
    54. 54. APPLICATION Secondary Crushers • Purpose • To produce an intermediate or final product • Feed Size – typically between 200 & 75 mm depending on primary crusher • Vibrating screen may be installed ahead to remove product size material. • Crusher types: • Standard cone crusher – traditionally • Horizontal Impact crusher as alternative • HPGR recently for diamond and iron ore http://mineralprocessingconsultant.com/ 54
    55. 55. APPLICATION Tertiary Crushers • Purpose: Produce the final product • Feed : 37 mm • Product : 12 mm • Crusher type: • Short head cone crusher • Longer crusher chamber and more even size distribution • Usually operated in closed circuit with a vibrating screen • HPGR and Nordberg Water Flush crushers have also been used. http://mineralprocessingconsultant.com/ 55
    56. 56. APPLICATION Quaternary Crushing • Purpose: • To produce fine dry product for downstream processing • Vertical Impact Crusher has been used at Newmont’s heap leaching operation in Uzbekistan. • High speed crusher that used high speed impact to effect particle reduction • Nordberg’s Gyradisc crusher uses a combination of impact and attrition to effect particle size reduction. • Applied in the industrial minerals and sand industry to produce finished products to 800 microns. http://mineralprocessingconsultant.com/ 56
    57. 57. CRUSHER TYPES • Jaw • Gyratory • Horizontal shaft impact crushers • Rotary breakers • Roll Crushers • Cone crushers • Gyradisc crushers • Vertical impact crusher http://mineralprocessingconsultant.com/ 57
    58. 58. FLOWSHEET – TWO STAGE CRUSHING (FINE PRODUCT) 58 http://mineralprocessingconsultant.com/
    59. 59. TWO STAGE CRUSHING (COARSE PRODUCT) 59 http://mineralprocessingconsultant.com/
    60. 60. THREE STAGE CRUSHING 60 http://mineralprocessingconsultant.com/
    61. 61. THREE STAGE CRUSHING 61 http://mineralprocessingconsultant.com/
    62. 62. THREE STAGE CRUSHING 62 http://mineralprocessingconsultant.com/
    63. 63. TWO STAGE WITH WATER FLUSH CRUSHER 63 http://mineralprocessingconsultant.com/
    64. 64. THREE STAGE CRUSHING – GOLD HEAP LEACH 64 http://mineralprocessingconsultant.com/
    65. 65. THREE STAGE CRUSHING AND WATER FLUSH CRUSHER 65 http://mineralprocessingconsultant.com/
    66. 66. WATER FLUSH CRUSHING 66 http://mineralprocessingconsultant.com/
    67. 67. SABC CONFIGURATION 67 http://mineralprocessingconsultant.com/
    68. 68. THREE STAGE CRUSHING WITH VERTICAL SHAFT IMPACTORS 68 http://mineralprocessingconsultant.com/
    69. 69. DISCUSSION POINTS! • What are the Problem areas of current equipment installation? http://mineralprocessingconsultant.com/ 69
    70. 70. SELECTION AND SIZING OF PRIMARY CRUSHER 70http://mineralprocessingconsultant.com/
    71. 71. INTRODUCTION • The rock / ore determines the type of crusher • The plant capacity determines the size of crusher Family of primary crushers • Gyratory • Double toggle Jaw • Single toggle Jaw • High speed roll crusher • Low speed sizer • Impactors • Hammer mill • Feeder breaker http://mineralprocessingconsultant.com/ 71
    72. 72. HISTORY 72 http://mineralprocessingconsultant.com/
    73. 73. MECHANICAL REDUCTION METHODS Four basic ways to reduce a material • Impact • Attrition • Shear • Compression http://mineralprocessingconsultant.com/ 73
    74. 74. COMPRESSION • Done between two surfaces • Gyratory and double toggle jaw uses this method Should be used when • Material is hard and tough • Material is abrasive • Material is not sticky • Uniform product with a minimum of fines is desired • The finished product is relatively coarse > 38 mm • Material will break cubically http://mineralprocessingconsultant.com/ 74
    75. 75. IMPACT • Refers to sharp , instantaneous impingement of one moving object against another • Two types • Gravity • Dynamic Conditions • Cubical particles are needed • Finished product must be well graded • Ore must be broken along natural cleavage lines • When material is too hard and abrasive or high moisture content http://mineralprocessingconsultant.com/ 75
    76. 76. ATTRITION • Scrubbing material between two hard surfaces • Hammer mills operate with close clearance between hammers and screen bars and reduce by attrition combined with shear and impact reduction. Conditions • When material is friable and non-abrasive • When top size control is not desired • When maximum of fines is required. http://mineralprocessingconsultant.com/ 76
    77. 77. SHEAR • Consists of trimming or cleaving action • Exploits the fact that the ratio of compressive strength to tensile and shear strength in the majority or rocks is approximately 10 : 1 • Low speed sizers break the rock in tension and shear by chopping action Conditions • When the material is somewhat friable and has low silica content • When material is soft to medium hardness • For primary crushing with a reduction ratio of 6 : 1 • When a minimum of fines is desired • When a relative coarse product is desired > 38 mm http://mineralprocessingconsultant.com/ 77
    78. 78. PRIMARY GYRATORY CRUSHERS • The main capacity advantage offered is centred around the Archimedes principal • They found that the crushing chamber provides more effective volume than a rectangular volume • The shaft grating speed adds a third dimension to crushing as opposed to two dimensional crushing http://mineralprocessingconsultant.com/ 78
    79. 79. GYRATORY CRUSHER Advantages • Designed for direct dump from trucks Lowest maintenance per ton processed of any designed crusher • Can handle crushing ore hardness up to 600 mPa • Easy handling of tramp material with hydraulic reiief system Disadvantage • Highest installed capital cost of any crusher design http://mineralprocessingconsultant.com/ 79
    80. 80. JAW CRUSHER ANIMATION VIDEO 1 80http://mineralprocessingconsultant.com/
    81. 81. WORKING PRINCIPLES OF THE JAW CRUSHER VIDEO 2 81http://mineralprocessingconsultant.com/
    82. 82. DOUBLE TOGGLE DESIGN • The swing Jaw of the Standard DT crusher pivots from an overhead shaft . • A Pitman hung from an eccentric shaft transmits motion through a pair of toggles at the bottom of the swing Jaw • Swing Jaw motion is greatest at the discharge opening. • The hinge pin is located behind the centreline of the crusher zone and it causes the swing Jaw to move perpendicular to the fixed Jaw. • This arrangement provides twice the force in crushing • Typical duty is 350 MPa http://mineralprocessingconsultant.com/ 82
    83. 83. DOUBLE TOGGLE JAW Advantages • Lower installed cost than a Gyratory crusher • Can handle high abrasion with low maintenance • Can handle tough crushing application upto 600 MPa nickel ores, iron ores, etc. Disadvantages • Same capacity limitations as the single toggle aw crusher • Substantially higher installed cost than a single toggle Jaw crusher • Same crushing size limitation as single toggle Jaw crusher http://mineralprocessingconsultant.com/ 83
    84. 84. SINGLE TOGGLE JAW CRUSHER • The rotation of the eccentric shaft causes the swing Jaw assembly to move in an elliptical path. • Maximum movement of the swing jaw assembly occurs at the top of the crushing chamber with minimum movement at the discharge opening • At all points in the crushing chamber the crushing action has both vertical and horizontal components. • Due to the rubbing action of this type of jaw, jaw plate wear is accelerated and power efficiency is lowered because the swing jaw is lifted on every stroke. http://mineralprocessingconsultant.com/ 84
    85. 85. SINGLE TOGGLE JAW CRUSHER Advantages • Lower installed cost than a double toggle • Lower power usage than a double toggle • Can handle sticky, muddy ore easier than a double toggle or Gyratory Disadvantages • Normal economic maximum capacity is 750 MTPH • Duty of crusher is for light or medium hard material • Does not handle high abrasive material as well as DT • Requires feeder • Primary crushing only http://mineralprocessingconsultant.com/ 85
    86. 86. LOW SPEED SIZERS • The low speed sizing principle is the combination of high torque / low roll speeds. • The interaction of tooth, spacer and roll set up a “sized void” which in turn sizes the material • Used for non-abrasive sticky type material bet 200 - 400 MPa • Application • Medium hard limestone, bauxite, kimberlite, gypsum, clay, shale and gold ore. http://mineralprocessingconsultant.com/ 86
    87. 87. LOW SPEED SIZERS Advantages • Can handle high tonnages – 12 000 MTPH • Low installation cost and minimum head room required • Low fines production • Low power consumption • Easy rejection of oversize feed – using discharge gates • Low reduction ratio • Peak power loading up to 8 times installed power • Not economic for low tonnage unless the material is very difficult to handle http://mineralprocessingconsultant.com/ 87
    88. 88. SINGLE TOGGLE VS. DOUBLE TOGGLE • ST has a larger angle of nip, the larger the nip angle the harder to grip the material.. • ST – greatest movement at the top • DT – greatest movement at the bottom • ST – Movement of jaw is in downward rolling direction which gives a force feed action assists in handling sticky material • Life of Jaw in ST is less than DT http://mineralprocessingconsultant.com/ 88
    89. 89. IMPACT CRUSHERS • Utilized in soft, non- abrasive application • Crushing availability and maintenance can economically offset against capital cost http://mineralprocessingconsultant.com/ 89
    90. 90. OPERATION OF AN IMPACT CRUSHER VIDEO 3 90http://mineralprocessingconsultant.com/
    91. 91. IMPACTOR ANIMATION VIDEO 4 91http://mineralprocessingconsultant.com/
    92. 92. IMPACT CRUSHER Advantages • Can handle larger size reduction 1000 : 75 • High reduction ratio compared to investment cost • Provides a high degree of fines • Can handle up to 2500 MTPH Disadvantages • Requires feeder • Cannot handle tramp metal • Higher power consumption as more fines are produced • High wear due to higher silica content + 8% http://mineralprocessingconsultant.com/ 92
    93. 93. FEEDER BREAKERS • Are utilised in soft to medium hard application • Coarsely break material for belt conveying • Frequently used for overburden and underground duty http://mineralprocessingconsultant.com/ 93
    94. 94. FEEDER BREAKER Advantages • Avoids costly site preparation and civil work • Can transfer and crush material in a single machine • Handles wet material with ease • Very low headroom • Can handle upto 2000 MTPH Disadvantage • Very low reduction ratio • Crushing takes place in breaker bars and chains which causes wear. http://mineralprocessingconsultant.com/ 94
    95. 95. PRIMARY CRUSHER SELECTION CRITERIA • Will it produce the desired product size at required capacity • Will it accept the largest feed size expected • What is the capacity to handle peak loads • Will it choke or plug • Is the crusher suited to the type of crushing plant design • Is the crusher suited for underground or in-pit duty • Can it handle tramp material without damage • How much supervision is required • How does the crusher resist abrasive wear • What is the power consumption http://mineralprocessingconsultant.com/ 95
    96. 96. PRIMARY CRUSHER SELECTION CRITERIA • Does the crusher operate economically with minimum maintenance • Does the crusher have an acceptable parts replacement cost • Does the crusher have easy access to internal parts • How does the initial cost of the machine compare to the long term operating cost. http://mineralprocessingconsultant.com/ 96
    97. 97. PRIMARY CRUSHER SELECTION - CAPACITY 97 http://mineralprocessingconsultant.com/
    98. 98. PRIMARY CRUSHER SELECTION – FEED SIZE 98 http://mineralprocessingconsultant.com/
    99. 99. PRIMARY CRUSHER SELECTION – PRODUCT SIZE 99 http://mineralprocessingconsultant.com/
    100. 100. PRIMARY CRUSHER SELECTION – COMPRESSIVE STRENGTH 100 http://mineralprocessingconsultant.com/
    101. 101. PRIMARY CRUSHER SELECTION – ABRASION INDEX 101 http://mineralprocessingconsultant.com/
    102. 102. PRIMARY CRUSHER SELECTION – CLAY CONTENT 102 http://mineralprocessingconsultant.com/
    103. 103. PRIMARY CRUSHER SELECTION – UNDERGROUND APPLICATION 103 http://mineralprocessingconsultant.com/
    104. 104. PRIMARY CRUSHER SELECTION – MOBILE PLANTS 104 http://mineralprocessingconsultant.com/
    105. 105. COMPUTER AIDED DESIGN OF JAW CRUSHER http://mineralprocessingconsultant.com/ 105
    106. 106. COMPONENTS OF A JAW CRUSHER http://mineralprocessingconsultant.com/ 106
    107. 107. MATERIAL FOR COMPONENTS OF JAW CRUSHER http://mineralprocessingconsultant.com/ 107
    108. 108. KINEMATIC ANALYSIS OF JAW CRUSHER • The geometry of the moving Jaw results in a movement change which has a great effect on the crushing action and particle breakage. • Based on the analysis of the moving jaw movement, the squeezing process and the crushing force distribution, the jaw plate wear on a macroscopic scale level aiming to predict the wear distribution on the jaw plate can be studied. http://mineralprocessingconsultant.com/ 108
    109. 109. SWINGING JAW MOVEMENT • The reciprocating jaw MN driven by the eccentric shaft AB does kind of a periodic plane swing movement. • Jaw crusher can be considered as a four bar mechanism in which link AN is the crank and OA is the fixed link http://mineralprocessingconsultant.com/ 109
    110. 110. • MN is the moving jaw and OM is the toggle bar. • In the analysis we are intended to find out the displacement, velocity and acceleration of various points on the swinging jaw plate. http://mineralprocessingconsultant.com/ 110
    111. 111. DATA EXTRACTED FROM STANDARD JAW CRUSHER • Length AN = 172 cm • Length MN = 1085 cm • Length OM = 455 cm • Co-ordinates of A (45.3 , 815.7) • Crank angle rotates from 0 to 360 degrees anticlockwise. http://mineralprocessingconsultant.com/ 111
    112. 112. CRANK ANGLE VS. ANGLE MADE BY MOVING JAW http://mineralprocessingconsultant.com/ 112
    113. 113. CRANK ANGLE VS. ANGLE BETWEEN MOVING JAW AND Y AXIS • The graph shows as the moving Jaw approached its counterpart which is stationary it tends to be vertical i.e. the angle between the moving Jaw and the Y axis decreases as a result the crushed product slips downwards. http://mineralprocessingconsultant.com/ 113
    114. 114. VERTICAL DISPLACEMENT VS. HORIZONTAL DISPLACEMENT http://mineralprocessingconsultant.com/ 114
    115. 115. HORIZONTAL DISPLACEMENT VS. CRANK ANGLE http://mineralprocessingconsultant.com/ 115
    116. 116. DISPLACEMENT VS. CRANK ANGLE http://mineralprocessingconsultant.com/ 116
    117. 117. POINTS ON THE MOVING JAW • Every point on the moving Jaw follows an elliptical path • When it moves towards the fixed Jaw, it goes vertically down and in the return stroke it moves vertically up. http://mineralprocessingconsultant.com/ 117
    118. 118. VERTICAL VELOCITY VS. CRANK ANGLE • The rate of change of vertical velocity is greater for the topmost point and decreases downwards http://mineralprocessingconsultant.com/ 118
    119. 119. HORIZONTAL VELOCITY VS. CRANK ANGLE • The rate of change of horizontal velocity is greater for the bottom most point and decreases upwards http://mineralprocessingconsultant.com/ 119
    120. 120. VELOCITY VS. CRANK ANGLE • The maximum rate of change of final velocity is greater for the points away from the crank. http://mineralprocessingconsultant.com/ 120
    121. 121. HORIZONTAL ACCELERATION VS. CRANK ANGLE • With progress from 0 to 360 degrees crank angle rotation the horizontal acceleration first increases then decreases http://mineralprocessingconsultant.com/ 121
    122. 122. VERTICAL ACCELERATION VS. CRANK ANGLE • With progress from 0 to 360 degrees crank rotation the vertical acceleration first decrease then increases http://mineralprocessingconsultant.com/ 122
    123. 123. ACCELERATION VS. CRANK ANGLE • The maximum acceleration is observed for the points farthest away from the crank angle http://mineralprocessingconsultant.com/ 123
    124. 124. EFFECT OF SLIDING MOTION ON JAW WEAR • Breakage Analysis • 3 types of Fracture mechanisms are observed • Abrasion • Cleavage • Shatter http://mineralprocessingconsultant.com/ 124
    125. 125. BREAKAGE ANALYSIS • The particle fracture mechanism in the Jaw crusher chamber is a mixture of cleavage and abrasion. The abrasion fracture is caused with the localised too much energy input to the area directly under the loading points and the • Friction between the Jaw plates and the particle. • The induced tensile stress results in the cleavage fracture. http://mineralprocessingconsultant.com/ 125
    126. 126. CRUSHING PROCESS • Theoretically a particle inside the crusher is crushed when it is compressed and fails in tensile stress. • In practice the particles also undergo slipping motion between the jaw plates • The forces acting on the element during the crushing process is shown below http://mineralprocessingconsultant.com/ 126
    127. 127. CRUSHING PROCESS • As the horizontal and vertical velocities of the moving jaw changes during the crushing process, the forces on the particle varies at different times. • When the component of the vertical velocity is greater than the components of the horizontal velocity the forces on the particle is shown in Fig. 3.3 (a) http://mineralprocessingconsultant.com/ 127
    128. 128. CRUSHING PROCESS • When the component of the vertical velocity is less than the components of the horizontal velocity the forces are shown in Fig. 3.3 (b) http://mineralprocessingconsultant.com/ 128
    129. 129. CRUSHING PROCESS • By a resolution of forces acting on the particle as shown in figure 3.3. it can be proved that conditions for the particle to slip against the fixed jaw plate is much greater than with the moving jaw plate. Condition for slide between the particle and the fixed jaw plate is unavoidable The chance for the particle to slide is greater with the fixed jaw than the moving jaw. Due to vertical motion irregular geometry of particles, a classification process before the particle fracture may exist during close process in which the particle adjustment may take place. http://mineralprocessingconsultant.com/ 129
    130. 130. WEAR ANALYSIS • Squeezing and sliding are the two principal factors affecting the Jaw plates wear • Squeezing plays the main role at the top of the crusher and the wear is small. • As the particles move down the crusher the probability of slip increases and the wear becomes more pronounced. • • At the middle lower part of the crusher where the ratio of the vertical distance to the horizontal stroke reaches a maximum value resulting in maximum wear of the crusher. • The slide between the fixed Jaw and particle is greater compared to the moving jaw hence the wear is dominant in the fixed jaw. http://mineralprocessingconsultant.com/ 130
    131. 131. DISCUSSION POINTS! • What are the flaws of the current primary crusher installation? • Where can we improve? http://mineralprocessingconsultant.com/ 131
    132. 132. SELECTION AND SIZING OF SECONDARY AND TERTIARY CRUSHERS 132http://mineralprocessingconsultant.com/
    133. 133. INTRODUCTION • Modern crushers have increased in performance • Evolved to focus greater on the quality of desired product • More stringent requirements are being placed in terms of shape and gradation. • Proper size reduction results in better recoveries • In milling feed preparation, the generation of fines and total top size reduction results in maximum mill productivity. • Proper understanding of crusher capabilities will minimize both installation and operating capabilities. http://mineralprocessingconsultant.com/ 133
    134. 134. HOW THE SYMONS CONE CRUSHER WORKS VIDEO 5 http://mineralprocessingconsultant.com/ 134
    135. 135. NEW GENERATION OF CONE CRUSHERS VIDEO 6 http://mineralprocessingconsultant.com/ 135
    136. 136. CONE CRUSHERS Modern Cone crushers • Increased performance capabilities • More power capabilities • Larger in size • Higher capacities • Better product shape • Higher percentage of final product yield New cone crushers • Safer more reliable hydraulic clamp and clearing system to protect the crusher from uncrushables and overload conditions • Adaptation of hydraulic setting adjustment system in the cone crusher design improves overall efficiency of crushing operation http://mineralprocessingconsultant.com/ 136
    137. 137. NEW CONE CRUSHERS • New generation of cone crushers provide • ease of operation • Simple maintenance • Uniform production throughout the liner life • High availability • Technology has evolved to include computer controls to maximize and optimize crusher performance based on application requirements • Modern devises provide real time feedback : • Power draw, cavity level, crushing force, temperatures, pressures, etc. http://mineralprocessingconsultant.com/ 137
    138. 138. CONE CRUSHER SELECTION CRITERIA Information required • Capacity required with consideration for expected availability • Expected gradation and product size Material characteristics • Specific gravity • Bulk density • Impact work index • Moisture content • Abrasion index • How the material breaks • Small scale lab tests and full scale pilot tests http://mineralprocessingconsultant.com/ 138
    139. 139. CONE CRUSHER DESIGN LIMITS Design limits • Volume limits • Power limits • Force Limits http://mineralprocessingconsultant.com/ 139
    140. 140. DESIGN LIMITS - VOLUME • Maximum rate of feed to the cone crusher without overfilling the cone crusher feed hopper • Function of • Speed of the crusher • Closed side setting CSS • Head angle • Material density Defining variables • Feed gradation • Crusher chamber configuration • Transport of material through the crusher cavity • Fragmentation characteristics http://mineralprocessingconsultant.com/ 140
    141. 141. DESIGN LIMIT - POWER • Power limit is reached when average power draw kW exceeds the installed motor power of the crusher. • Ore of high impact work index or strong resistance to fragmentation tend to reach or exceed the power limit easily. • Pilot scale test work can provide information regarding power consumption http://mineralprocessingconsultant.com/ 141
    142. 142. DESIGN LIMIT – FORCE FACTOR • The force limit of a crusher is reached when the combined forces exerted during crushing exceeds the force available on the machine to hold the desired closed side setting. • Force limits may be exceeded due to • uncrushables material entering the crushing chamber • Operating at a small closed side setting • Packing of wet sticky material • High power draws • Incorrect crushing cavity design http://mineralprocessingconsultant.com/ 142
    143. 143. CONE CRUSHER SIZES AND CAPACITY RANGES 143 http://mineralprocessingconsultant.com/
    144. 144. SECONDARY CONE CRUSHER SELECTION • Ensure the feed material does not exceed the acceptable maximum size for the crusher • Determine the capacity requirements at a given closed side setting based on a 4/6:1 reduction ratio. Example • maximum feed material 200mm • Capacity 500 tph • Table 1 : HP 300 • At 32 mm CSS the crusher is unable to achieve a minimum of 500 tph • Table 1 : HP500 http://mineralprocessingconsultant.com/ 144
    145. 145. SECONDARY CONE CRUSHER SELECTION Correct cavity configuration • The cavity configuration has to suit the feed gradation so that the maximum crushing performance and liner utilisation is achieved • Several cavity configurations are available for cone crushers to maximise performance. • An improper liner configuration applied can create high crushing forces leading to adjustment ring movement , exceeding crusher force limit. http://mineralprocessingconsultant.com/ 145
    146. 146. CASE STUDY: HP700 REPLACING HAMMER MILL Copper mine in Portland • Hammer mill used to prepare rod mill feed • Hammer mill replaced by HP700 cone crusher Results • 20% gain in energy efficiency • By reducing the rod mill feed from 80% passing 30 mm to 80% passing 14 mm. http://mineralprocessingconsultant.com/ 146
    147. 147. CASE STUDY: HP700 REPLACING HAMMER MILL 147 http://mineralprocessingconsultant.com/
    148. 148. CASE STUDY: HP700 REPLACING HAMMER MILL 148 http://mineralprocessingconsultant.com/
    149. 149. THE PRE-CRUSHER OPTION • The most recent evolution for pebble crushing finds a basis in the presumption that the most appropriate primary mill feed contains a minimum amount of critical size material. • The initial feed of the primary mill should dominantly consist of fine and coarse material. • Coarse material serves as impact media and fines as transport medium for down stream processing. • Pre-crushing targets to convert the middling to fine fraction. http://mineralprocessingconsultant.com/ 149
    150. 150. CASE STUDY: PRE- CRUSHING Troilus Mine • 150 – 50 mm is pre-crushed using an HP 700 cone crusher • Production increase and operating cost decreased. Kidston Mine • All primary crusher ore is pre - screened to remove fines • All +50 mm oversize is crushed at maximum reduction ratio to deliver maximum fines. • Proved effective in boosting milling productivity and lowering operating cost. http://mineralprocessingconsultant.com/ 150
    151. 151. TYPICAL PRE-CRUSHER INSTALLATION 151 http://mineralprocessingconsultant.com/
    152. 152. TRACK MOUNTED CONE CRUSHER VIDEO 7 152 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    153. 153. CASE STUDY : INFLUENCE OF ECCENTRIC SPEED OF CONE CRUSHER PRODUCTION AND OPERATION 153 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    154. 154. CASE STUDY : PILOT TEST PROGRAM • The research was performed in Tampere, Finland using an HP 200 cone crusher • The study can be separated into three groups of test: • Base tests • Fixed tonnage tests • Feed size distribution tests • The base tests were used to measure the crushers maximum performance for a given eccentric speed. • The fixed tonnage tests simulated operating conditions where the feed rate to the crusher is limited below the maximum capacity based on the base eccentric speed and CSS 154 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    155. 155. CASE STUDY : PILOT TEST PROGRAM • A third set of tests utilized a different feed size in order to verify results as well as reducing the effect of top size particles possibly being inhibited to enter the crushing cavity. • The tests in each group used the same homogenous feed of known characteristics with feed sample being taken every forth test for verification. 155 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    156. 156. CASE STUDY: PILOT TEST RESULTS Overall • Most of the data showed clear trends in capacity, power and discharge size distribution as the eccentric speed was varied. Base testing results • For the base testing where each test was operated at the optimal cavity level to develop a baseline for maximum production, the results matched theory. • As the eccentric speed was increased the capacity decreased in a nearly liner manner. 156 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    157. 157. CASE STUDY : BASE TESTING RESULTS • On average, the total capacity tph fluctuated by 22.5% over a design speed range of 34%. • The increase in capacity but decrease in reduction as the speed is lowered results in relatively low changes to power draw as shown in figure 2. 157 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    158. 158. CASE STUDY: BASE TESTING RESULTS • For a base case testing with a full cavity throughout, it was seen that there was slight benefits in throughput and energy efficiency when the crusher was operated at near the minimum design eccentric speed. • The higher capacity outweighed the slight loss in reduction through the machine and the machine was more mechanically efficient at the lower speeds. • It was best to operate at the low end of the speed range. 158 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    159. 159. CASE STUDY: 32 MM CSS PRODUCTION VS. SPECIFIC ENERGY 159 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    160. 160. CASE STUDY : 19 MM CSS PRODUCTION VS. SPECIFIC ENERGY 160 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    161. 161. CASE STUDY: FIXED TONNAGE TEST RESULTS • The tests operated at a fixed tonnage were conducted to simulate a crushing application where the crusher is not the limiting equipment therefore the tonnage to the crusher is fixed by other plant limitations therefore the crusher cannot normally achieve a full choke condition. • The power draw of the crusher dropped significantly as the speed decreased resulting in a lower kW/t specific energy through the machine. • There was a major shift in reduction through the machine ‘ 161 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    162. 162. CASE STUDY: FIXED TONNAGE TEST RESULTS • The tph of the -12.5 mm product fell slightly as the eccentric speed reduced from the reference speed by 20% • The phenomenon occurred at the point where the cavity level in the crusher could not fill up half of the crushing chamber and the discharge became coarser • While operating with a higher cavity level was more efficient, the crusher was more mechanically efficient at the lower speeds 162 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    163. 163. CASE STUDY : FIXED TONNAGE TEST RESULTS • For the fixed tonnage tests there was a marked improvement in the variation of power draw as the speed and cavity level increased. 163 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    164. 164. CASE STUDY : PRACTICAL APPLICATION • There are a number of uses for these principles in a crushing plant. The main points are as follows: • Changing the speed to find a more optimal setup than that supplied by the manufacturer. • Manipulating the speed based on current static plant conditions, • And dynamic control of eccentric speed in a control system. • The optimization of eccentric speed may be beneficial where feed conditions and plant requirements change. • Dynamically manipulating the eccentric speed using a variable frequency drive has not been widely used. 164 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    165. 165. CASE STUDY : PRACTICAL APPLICATION • A dynamic control system can be used to vary the speed resulting in benefits to production and energy efficiency. • E.g. When the throughput of the crusher is high it could be operated most efficiently in the lower speed range. • If the throughput requirements drop for a short period of time it would be more productive and efficient to increase the speed of the crusher and operate with a fuller chamber. • An underlining benefit for greater control of the crusher operation is maintaining a choke fed condition, which has benefit to production , operating cost and mechanical health of the crusher. 165 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    166. 166. DISCUSSION POINTS! • Choke feeding in your current application, the pros and cons. 166 Selectionandsizingof Secondaryantertiarycrushers http://mineralprocessingconsultant.com/
    167. 167. SELECTION AND SIZING OF HIGH PRESSURE GRINDING ROLL CRUSHERS 167http://mineralprocessingconsultant.com/
    168. 168. NEW CRUSHERS ON THE MARKET VIDEO 8 http://mineralprocessingconsultant.com/ 168
    169. 169. HPGR INTRODUCTION • HPGR are well established in the cement industry for the grinding of clinker, limestone, slag and other relatively non-abrasive material. • Minerals are 20 – 100 times more abrasive than cement raw materials. • Acceptance by the minerals industry has required the development of special wear protection surfaces and rapid change out procedures for the rolls. • Range of grinding • Coarse < 75 mm • To grinding of fine concentrate < 100 microns http://mineralprocessingconsultant.com/ 169
    170. 170. HPGR INTRODUCTION • Moisture content up to 12 % • Machines are available with capacities up to 3000 tph • Installed power up to 6000 kW http://mineralprocessingconsultant.com/ 170
    171. 171. HPGR INSTALLED IN DIAMOND AND IRON ORE INDUSTRIES 171 http://mineralprocessingconsultant.com/
    172. 172. HPGR – L/D RATIOS Length to Diameter ratio • Is it more advantageous to design rolls with smaller diameters and larger widths or larger diameters and smaller widths? http://mineralprocessingconsultant.com/ 172
    173. 173. HPGR – L/D RATIO • The decision as to which approach to adopt is capital. • It has an impact not only on the performance of the crusher but also major impact on the design of the individual components and on the general layout of the unit. • The minimum roll diameter is prescribed by the outside diameter of the bearings and the thickness of the bearing block. • The bearings are sized according to the installed grinding force. http://mineralprocessingconsultant.com/ 173
    174. 174. HPGR – L/D RATIO • The size of the bearing determines the shaft diameter and pre- determines the manner in which the gear box and shaft are to be connected. • Larger rolls with low L/D ratios offer greater freedom in selecting the most appropriate bearings. • The larger roll diameter makes the connection between the shaft and the gear box simple to execute. And allow large gear boxes to be located on one side to save space and facilitate maintenance. http://mineralprocessingconsultant.com/ 174
    175. 175. HPGR – ROLL DESIGN • Three different roll designs have been successfully applied: • Solid rolls • Rolls with tyres • Rolls with segmented liners http://mineralprocessingconsultant.com/ 175
    176. 176. HPGR – CRITERIA FOR SELECTING OPTIMUM DESIGN • The balance between operating and investment cost • The acceptable lifetime and frequency of replacement • The tolerable down time for liner replacement http://mineralprocessingconsultant.com/ 176
    177. 177. HPGR - COMPARISON Tyres • Lower investment cost • No interfaces (joints) • Longer lifetime • Lower wear cost • No pressure restriction Segments • Higher investment cost • Joints between segments require more maintenance due to washouts • Shorter lifetime • Higher wear cost • Only for low pressure http://mineralprocessingconsultant.com/ 177
    178. 178. HPGR - WEAR PROTECTION SURFACES 178 http://mineralprocessingconsultant.com/
    179. 179. HPGR - WEAR PROTECTION OF ROLL SURFACES 179 http://mineralprocessingconsultant.com/
    180. 180. HPGR – KEY PARAMETERS • Achieve the throughput requirements and to achieve the desired product fineness Throughput • Function of roll dimension • Type of roll surface • Feed material properties • For a given material and roll dimension the throughput is controlled by the roll speed. http://mineralprocessingconsultant.com/ 180
    181. 181. HPGR – KEY PARAMETERS Product Fineness • Controlled by the grinding force applied to the material bed between the rolls. • The grinding force creates the pressure in the material bed which causes micro- cracks and breakage of the particles. • The correlation between particle breakage and grinding force required needs to be determined for each material • Key parameters are • Specific throughput rate • Specific press force to be applied to achieved the desired comminution results http://mineralprocessingconsultant.com/ 181
    182. 182. HPGR – THROUGHPUT RATE VS. ROLL SPEED 182 http://mineralprocessingconsultant.com/
    183. 183. HPGR – FEED MOISTURE CONTENT VS. THROUGHPUT RATE 183 http://mineralprocessingconsultant.com/
    184. 184. HPGR – THROUGHPUT VS. SIZE DISTRIBUTION 184 http://mineralprocessingconsultant.com/
    185. 185. HPGR – PRODUCT FINENESS 185 http://mineralprocessingconsultant.com/
    186. 186. HPGR – PRODUCT OF VARIOUS ORES 186 http://mineralprocessingconsultant.com/
    187. 187. HPGR – ENERGY CONSUMPTION VS. FORCE 187 http://mineralprocessingconsultant.com/
    188. 188. HPGR – ENERGY INPUT VS. ROLL SURFACE 188 http://mineralprocessingconsultant.com/
    189. 189. HPGR - ENERGY INPUT FOR VARIOUS ORES 189 http://mineralprocessingconsultant.com/
    190. 190. HPGR – ENERGY INPUT VS. GRINDING FORCE 190 http://mineralprocessingconsultant.com/
    191. 191. HPGR WEAR FACTORS 191 http://mineralprocessingconsultant.com/
    192. 192. HPGR – ROLL DIAMETER VS. ROLL SPEED 192 http://mineralprocessingconsultant.com/
    193. 193. HPGR - APPLICATION 193 http://mineralprocessingconsultant.com/
    194. 194. HPGR – PEBBLE CRUSHER 194 http://mineralprocessingconsultant.com/
    195. 195. HPGR – PRE-CRUSHER 195 http://mineralprocessingconsultant.com/
    196. 196. HPGR – REPLACEMENT OF 3RD AND 4TH STAGE 196 http://mineralprocessingconsultant.com/
    197. 197. DISCUSSION POINTS! • Is it possible to include HPGR in your circuit? 197 http://mineralprocessingconsultant.com/
    198. 198. ORE CHARACTERISATION 198http://mineralprocessingconsultant.com/
    199. 199. CHARACTERISATION - UNDERSTANDING THE ORE BODY AND THE METALLURGY • The best possible characterisation of the ore body will enhance the ability to extract better outcomes from a mine to mill application. • The greater data, the better characterisation of the ore body. Properties. • This characterisation is important in developing extraction and processing strategies which enhance the productivity gains possible from a mine to mill application (JKMRC 1998) http://mineralprocessingconsultant.com/ 199
    200. 200. CHARACTERISATION - UNDERSTANDING THE ORE BODY AND THE METALLURGY • At its simplest , characterisation is about developing the best possible understanding of the ore body , in particular its variability. • One of the first comprehensive characterisation studies was reported by Simkus and Dance (1998) at the Highland Valley Mine Highlands Valley • Had developed a program mapping the hardness of different ore types, since the late 1970’s. • By late 1990’s , drill monitors were being used to provide an estimate of ore hardness of subsequent blasted ore. • Ore was then tracked to stockpiles using mine dispatch systems and movement through stockpiles was modelled. http://mineralprocessingconsultant.com/ 200
    201. 201. CHARACTERISATION - UNDERSTANDING THE ORE BODY AND THE METALLURGY • An image analysis system was used to provide an estimation of the feed size distribution to the SAG mills. • Relationships were developed between ore hardness, feed size and mill throughput. • This approach provided a strong ability to predict expected mill throughput information which could then be utilised in process control. http://mineralprocessingconsultant.com/ 201
    202. 202. CHARACTERISATION - UNDERSTANDING THE ORE BODY AND THE METALLURGY Rock Mass Properties • Standard rock mass properties are usually obtained as geotechnical information from drill core and include: • Rock Mass Rating • Rock quality designation • Point load Index • Young’s Modulus • Poisson’s Ratio • Unconfined Compressive stress • In-situ block size • Joint spacing http://mineralprocessingconsultant.com/ 202
    203. 203. CHARACTERISATION - UNDERSTANDING THE ORE BODY AND THE METALLURGY Metallurgical Process Parameters • These data typically include: • Grades, including the grades of gangue minerals and minor elements • Grindability data, principally related to ore hardness, as measured by bond work indices and JKMRC grinding model parameters, • Flotation grade and recovery data as determined by laboratory flotation tests • Mineral liberation • Lithology • Geological Alteration • Acid forming potential of ore http://mineralprocessingconsultant.com/ 203
    204. 204. CHARACTERISATION - UNDERSTANDING THE ORE BODY AND THE METALLURGY Predictive Models • Models frequently used in mine to mill studies include • Mine block models incorporating geotechnical and geometallurgical parameters. • Blast fragmentation models • Muck pile models • Comminution models • Models which predict the final stockpile shape resulting from open pit blast are increasingly useful when it is desirable to understand where material of different properties, notably grade, reside in the muck pile after blast. http://mineralprocessingconsultant.com/ 204
    205. 205. CHARACTERISATION - UNDERSTANDING THE ORE BODY AND THE METALLURGY Conclusions • The literature analysis suggests that the tools required to implement Mine to mill approach are available in acceptable form. • Many of these hardware and software tools are provided by established suppliers and have been successfully implemented. • Most tools are also subjected to research and further development • The area of greatest need is the availability of tools to monitor mine to mill outcomes. • To date these have been developed at individual sites • More generic software tools would be useful. http://mineralprocessingconsultant.com/ 205
    206. 206. CASE STUDY: ANTAMINA BOOSTS THROUGHPUT FOR HARD ORES http://mineralprocessingconsultant.com/ 206
    207. 207. CASE STUDY: ANTAMINA BOOSTS THROUGHPUT FOR HARD ORES Introduction • The ore body that Compania Minera Antamina has been mining in Peru since 2001 contains two principal ore types, copper molybdenum ores and much harder copper zinc ores which exist about 70 : 30 ratio. • Historically the copper zinc ores were processed at a far slower rate and it was clear that something needed to be done. • A collaboration between Metso Process Technology and Innovation and the Mine began in 2007 which aimed to optimise the entire comminution process. http://mineralprocessingconsultant.com/ 207
    208. 208. CASE STUDY: ANTAMINA BOOSTS THROUGHPUT FOR HARD ORES • The team began by auditing the drill and blast practice as well as sampling the crushing and grinding circuit. • This helped them to develop models that would reveal what each step was achieving and what could be tweaked to improve performance • The mine and the processing plant was then benchmarked. • The models were calibrated and then a number of scenarios of operating strategies for both mine and process plant were run. • An in-depth review of existing practices were carried out. http://mineralprocessingconsultant.com/ 208
    209. 209. CASE STUDY: ANTAMINA BOOSTS THROUGHPUT FOR HARD ORES • The ore was categorised in varying groups of hardness. • Blast practices were audited and blast fragments were measured which made it possible to benchmark existing practices, and to define the main constraints related to wall stability and control ore dilution and environmental aspects. • Site specific models for the comminution process was created and it became evident that the largest potential gains to the blast could be found. • The basic idea was to increase the powder factor using more explosives to create a finer ROM fragmentation so that downstream equipment would treat the ore with ease. http://mineralprocessingconsultant.com/ 209
    210. 210. CASE STUDY: ANTAMINA BOOSTS THROUGHPUT FOR HARD ORES • In the drilling process the drill pattern ( burden and spacing) was reduced • By maintaining the same type and amount of explosives in each drill hole, the corresponding blast powder factor rose from 0.35 - 0.54 kg/ton • In addition switching to electronic detonators proved to be more reliable and ensured that blasts went off according to plan. • A pebble crusher was also installed and modification to the pulp lifters were made. http://mineralprocessingconsultant.com/ 210
    211. 211. CASE STUDY: ANTAMINA BOOSTS THROUGHPUT FOR HARD ORES Conclusion • Mine to mill optimisation work increased throughput by 30 % • Process plant improvements contributed 10 % increase in throughput • Reduction in hardness of the copper zinc ore contributed 15% to the increase in throughput • As of 2011 Antamina was processing copper zinc ores at an average rate of 4400 tons per hour, up 60 % from the performance prior to 2007 • The copper – molybdenum ore also saw an increase to 4800 tons per hour. http://mineralprocessingconsultant.com/ 211
    212. 212. CASE STUDY : BATU HIJAU (INDONESIA) PRODUCTION PLANNING FOR THE COMBINED MINE TO MILL OPERATION 212http://mineralprocessingconsultant.com/
    213. 213. CASE STUDY: INTRODUCTION • The Batu Hijau copper – gold operation commenced a mine to mill program in 2001 with the standard initial objective: • To modify blast practice to improve SAG mill throughput. • The work presented spans over 10 years of development. http://mineralprocessingconsultant.com/ 213
    214. 214. CASE STUDY BATU HIJAU • Using rock mass characterisation data, ore hardness and blast design data, simple regression models were developed which predicted SAG mill throughput. • This was done for different zones in the ore body ultimately resulting in separate throughput predictions for 16 ore body domains. • JKSimMet was used to enhance the initial regression models in order to more accurately predict the expected SAG mill throughput for the different domains. http://mineralprocessingconsultant.com/ 214
    215. 215. CASE STUDY : BATU HIJAU • Attention then turned to developing the best blasting practice for the domains to reduce fragmentation top size in order to improve loading rates in the pit and increase grinding circuit throughput. • Different blast designs were developed for each domain. • The modelling approach also provided a basis for ore scheduling and production forecasting http://mineralprocessingconsultant.com/ 215
    216. 216. CASE STUDY : BATU HIJAU • The second phase of the study was based on improving prediction of mill throughput based on improved orebody characterisation. • Improving prediction of blasting performance and refining mill models. • The other major advance has been the use of the modelling approach for both short and long term production planning. http://mineralprocessingconsultant.com/ 216
    217. 217. CASE STUDY : BATU HIJAU • In 2007 the equations linking mill throughput to measurable variables were coded into the mine block model so that throughput predictions became a direct output from the block models. • As previously the throughput relations were based on regression models of the tph as a function of characterisation variables. • In effect the models established a benchmark performance which can be expected when mining and processing ore from different domains. http://mineralprocessingconsultant.com/ 217
    218. 218. CASE STUDY : BATU HIJAU Outcomes first phase • Productivity gains of 10% for loading rates in the pit and 10-15% increases in SAG mill throughput for the individual ore domains were reported. Some of the important requirements for the effective implementation of the Batu Hijau M2M • Strategy included: • The need for a dedicated team of involved staff from geology, mining, milling IT support • Strong and on-going support of senior management • Best possible orebody characterisation – an on-going requirement with continuing updating of the domain models http://mineralprocessingconsultant.com/ 218
    219. 219. CASE STUDY : BATU HIJAU Outcome first phase • Accurate models of blasting and comminution to establish expected performance for each domain and the best balance in cost and effort between blasting and milling for each domain http://mineralprocessingconsultant.com/ 219
    220. 220. CASE STUDY : BATU HIJAU Outcome second phase • The second phase of the Batu Hijau study provides the basis for a much wider range of M2M applications than just increasing SAG mill throughput. • There is a demonstrated ability to predict mill throughput over the long term to +/-2% accuracy • At the core of the latest developments is a greater ability to predict mill throughput with considerable accuracy for different ore sources. http://mineralprocessingconsultant.com/ 220
    221. 221. CASE STUDY : BATU HIJAU • The applications of that capability include: • The understanding of the expected or benchmark performance against which actual performance can be compared. • Deviations from the expected can be identified and remedial action to regain performance can be better targeted • The availability of a sound basis on which improvements in the grinding circuit can be identified, implemented and measured • A tool which is an integral part of both long and short term production planning to achieve required production rates http://mineralprocessingconsultant.com/ 221
    222. 222. ORE DRESSING STUDIES – WHAT IS INVOLVED 222http://mineralprocessingconsultant.com/
    223. 223. ODS - WHAT IS INVOLVED Introduction • Ore dressing studies the characterisation of the ore body with respect to metallurgical properties. • In conjunction with the project requirements, geologists and mineral resource management, a sampling program is compiled for the specific ore body. • These samples are characterised with respect to various flowsheet and data obtained from the characterisation work is analysed and evaluated to improve the process recovery . • This provides information with regards to risk minimisation, for both plant design envelopes as well as operational efficiency http://mineralprocessingconsultant.com/ 223
    224. 224. ODS - KNOWLEDGE FLOW224 http://mineralprocessingconsultant.com/
    225. 225. ODS - IN AN ORE BODY DEVELOPMENT 225 http://mineralprocessingconsultant.com/
    226. 226. ODS - GENERIC DIAGRAM FOR SAMPLE CHARACTERISATION 226 http://mineralprocessingconsultant.com/
    227. 227. ODS - COMMINUTION CHARACTERISATION • Test work consists of a suit of laboratory and pilot plant scale tests • Laboratory tests are typically rock mechanic tests as used by equipment manufacturers to provide performance guarantees for comminution equipment. • These also include drop weight tests , a methodology used to determine the extent of breakage resistance due to impact and abrasion. http://mineralprocessingconsultant.com/ 227
    228. 228. ODS - COMMINUTION CHARACTERISATION • Depending on the requirement of the specific ore dressing study, i.e. feasibility study , pilot scale tests can be conducted on various comminution equipment to validate laboratory scale test results and generate plant design information. • Samples can also be provided to equipment manufactures to conduct their own tests http://mineralprocessingconsultant.com/ 228
    229. 229. ODS - DATA ANALYSIS AND INTERPRETATION • The data generated from the characterisation tests is analysed and interpreted by process specialists. • This is a collaborated effort amongst in-house specialists, proprietary and commercial software, research institutes, and equipment manufactures and suppliers. • Interpretation in this context means that key metallurgical parameters are determined and operating envelopes are established. • Also potentially problematic ore types are identified and process recommendations are made. http://mineralprocessingconsultant.com/ 229
    230. 230. ODS - DATA ANALYSIS AND INTERPRETATION • The output results in key plant design information. • E.g. comminution characterisation predicts the product size distribution and mass balance via simulation for scrubbing and each of the crushing stages. http://mineralprocessingconsultant.com/ 230
    231. 231. ODS - INTEGRATION • The role of the metallurgist is key in generating the flowsheet design knowledge package through the interaction with a variety of process specialists and process engineers. • Important major ore related problem areas within a specific ore type are also highlighted. • This means that such problem areas and solutions are integrated within the overall process design. • Depending on the phase of the project the integration process also includes a level of simulation of the ore dressing study, and derived flowsheet options that resulted from the characterisation of the various ore types. http://mineralprocessingconsultant.com/ 231
    232. 232. ODS - INTEGRATION • Simulation enables critical investigation of all system attributes, and the ability of the circuit design to deliver finished product with out recycling. • Raw ore dressing information and knowledge is traded off against practical operational constraints, which leads to a fit-for-purpose design • That has the best chance of maximizing recovery of minerals from in-situ resources. http://mineralprocessingconsultant.com/ 232
    233. 233. ODS - PLANT DESIGN • To reduce the risk of selecting incorrect equipment from a vast array of possibilities a formalised set of tools to guide equipment selection and plant design have been developed • These tools consist of commercially available as well as proprietary tools • Process engineers are provided with basic flow diagrams and related metallurgical parameters. • The process engineer will then expand on the original ore dressing flowsheet provided and develop a number of flowsheet based on the project requirements. http://mineralprocessingconsultant.com/ 233
    234. 234. ODS - PLANT DESIGN • Completed ore dressing study assists the process engineer to rapidly evaluate scenarios using existing models and create an understanding of how the metallurgical envelope of characteristics develop through the ore body. • An evaluation of proposed solutions against a background of knowledge derived from the study is then conducted. • The knowledge derived from the study supports the engineer in the design phase and assists in reducing project risk and increases confidence in the approved flowsheet. http://mineralprocessingconsultant.com/ 234
    235. 235. PROFIT BASED GRINDING CONTROLS Case Study : Sierrita Program controller : Duval Corporation 235http://mineralprocessingconsultant.com/
    236. 236. CASE STUDY : SIERRITA Introduction • The comminution circuit represents the largest user of energy in the Mineral Processing Industry • As the grades of ore reduces the economics of energy usage becomes more significant. • Pertinent control theory for the control of comminution circuits has been known for a long time but it is of recent years that practical techniques and robust computer control architectures for these systems have become available http://mineralprocessingconsultant.com/ 236
    237. 237. CASE STUDY : SIERRITA Description of the Plant • Wet grinding circuit treats 90 000 stpd • Sixteen x Allis-Chalmers overflow ball mills are operated in parallel in a conventional closed circuit wet grinding system. • The very low grade ore, variable crusher product, and changes in ore hardness produces disturbances that upset the performance of the grinding circuit. http://mineralprocessingconsultant.com/ 237
    238. 238. CASE STUDY : SIERRITA Instrumentation • Variable feeder • Feeder Weight measurement system • Feed water flow meter • Sump water flow rate • Sump level indicator • Mill power draft • Pump amperage • Control valves to feed and sump water • All the other variables are calculated using inferential techniques http://mineralprocessingconsultant.com/ 238
    239. 239. CASE STUDY : SIERRITA Process Analysis study • Fig. 2 shows a schematic diagram of a ball mill / cyclone control system • This diagram shows the instrumentation and the calculated variables use in the control strategy. • From the process analysis study several objectives were established. http://mineralprocessingconsultant.com/ 239
    240. 240. CASE STUDY : SIERRITA Objectives • Reduction of mill feed size • Reduction of mill power consumption • Extending mill transport conditions • Investment in variable speed drives • Identification of proper linking of manipulated variables with control variables • Identification of inferred measurements and signal conditioning of the raw measurements http://mineralprocessingconsultant.com/ 240
    241. 241. CASE STUDY : SIERRITA Disturbances • Mill feed particle size distribution due to bin segregation and crusher circuit operation • Ore hardness and ore mineralogical structure and composition due to natural mining characteristics • Pumping / classification limitations and equipment wear. • Process analysis study showed that the calculations of the inferred calculated variables can provide adequate information for the development of control strategy http://mineralprocessingconsultant.com/ 241
    242. 242. CASE STUDY : SIERRITA Design of the plant control strategy • Fig. 3 shows that for a given ore there is a unique milling rate to provide the grind size that will yield maximum profit under certain economic conditions • A higher milling rate can be achieved with a coarser grind which is off set by losses in recovery due to poor liberation • A finer grind producers better recoveries but loss in throughput rate. • Swings outside the given band produces losses http://mineralprocessingconsultant.com/ 242
    243. 243. CASE STUDY : SIERRITA Design of plant control strategy • Fig. 4 shows the control objectives and limiting conditions that the control system must overcome to produce a profit. • The main controller is the mill load constraint controller for safe operation followed by the grind cut controller for profitable operation • The mill load constraint controller involves the changing mill transport constraint and sets the tonnage for feasible operation http://mineralprocessingconsultant.com/ 243
    244. 244. CASE STUDY : SIERRITA Design of plant control strategy • The grind cut inferential controller maintains the optimal liberation, if process operational limits permit. • The curves depicted in fig. 3 and 4 are not unique and are changing constantly. • Thus the information must be handled on a timely basis in a computer system. • The computer system will in turn provide for adapting values of the moving constraint and set points. This known as online adaptive decision making or control. http://mineralprocessingconsultant.com/ 244
    245. 245. CASE STUDY : SIERRITA Grinding controls • The primary objective of the grinding controls system is to provide a flexible , adaptive, easy to use system to: • Maintain an optimal throughput depending on the ore conditions. This will provide the downstream process with a constant size distribution for improved recovery. • Or to maintain a stable operation while assisting the operator in maximizing the throughput, avoiding frequent upsets or spills and maintaining an adequate grind. http://mineralprocessingconsultant.com/ 245
    246. 246. CASE STUDY : SIERRITA Grinding controls Simplified function block control strategy http://mineralprocessingconsultant.com/ 246
    247. 247. CASE STUDY : SIERRITA The four principle controllers • The ball mill load control system • The grind index control strategy • The ball mill transport index control strategy • Sump level controller http://mineralprocessingconsultant.com/ 247
    248. 248. CASE STUDY : SIERRITA The ball mill load controller • This is the main controller • Any additional capacity of the ball mill depending on the grind setting is sensed by the ball mill load controller and the feed rate is increased. http://mineralprocessingconsultant.com/ 248
    249. 249. CASE STUDY : SIERRITA Control Design http://mineralprocessingconsultant.com/ 249
    250. 250. CASE STUDY : SIERRITA MAIN CONTROLLER WINDOW DISPLAY http://mineralprocessingconsultant.com/ 250
    251. 251. CASE STUDY : SIERRITA Computer Architecture for plant management http://mineralprocessingconsultant.com/ 251
    252. 252. CASE STUDY : SIERRITA Overall plant control strategy • The current objective of increasing the recovery / profit by running an optimal throughput can be enhanced by proper co-ordination of the plant activities. • Fig. 8 shows the computer architecture used to integrate the distributed control system with process management activities • Four process control units are networked to two operator interface units. • The plant host computer is also used for engineering analysis of operating and lab oratory information with statistical modelling, process analysis and simulation and reporting software packages. http://mineralprocessingconsultant.com/ 252
    253. 253. CASE STUDY : SIERRITA Conclusions • A profitability concept was transformed into a feasible mode of operation. • The tonnage setting can be safely pushed up to 400 stph from 250 stph while maintaining metallurgical performance. http://mineralprocessingconsultant.com/ 253

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