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Dynamic Simulation of
Size Reduction Operations fromMine-to-Mill
by
J.A. Herbst and W.T. Pate
J.A.
Herbst&Associat
es,
LLC
POBox2568
K
ealakekua,H
I96750-2568
om
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Kona
HawaiiMauiMolokai
Oahu
Kauai
Honolulu
Tahiti
California Mexico
Hilo
J.A. Herbst & Associates
Australia
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The Cost of Comminution
WorldwideEnergy Consumed Worldwide
2.6 x 1010 US$/yearWear Parts Consumed Worldwide
= 5 billion US$/year
100%100%
00
Product Size
EnergyEfficiency
50%50%
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Typical Breakdown of
Comminution Costs
Explosive Fracturing 1%
Coarse Crushing 2%
Fine Crushing 20%
Grinding 77%
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Mine-to-Mill Simulation
Real World Model Object
Flowsheet
Simulator
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Benefits of
Object Oriented ProgrammingA software object contains code and data which simulate the
pertinent characteristics of a physical device or stream
PROGRAM MAIN
CALL MINE ( )CALL TRUCK ( )
CALL CRUSH(FEED,CRUSHPROD)
CALL STORAGE ( )
CALL SCREEN(FEED,SCREENPROD)
CALL MILL(FEED,MILLPROD)
SUBROUTINE MINE ( )SUBROUTINE TRUCK ( )
SUBROUTINE MILL(FEED,MILLPROD)
SUBROUTINE STORAGE ( )
SUBROUTINE CRUSH(FEED,CRUSHPROD)
SUBROUTINE SCREEN(FEED,SCREENPROD)
Object Oriented Traditional
When process objects are connected bystreams they are linked for computation
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Conceptual Design of
MinOOcad
ProcessObject
Object
Properties
ObjectDisplay
Stream
Object
Stream
Object
( )ttO +2
( )ttO +1
( )tI
Object Menu
ContainerStream
Object #1
Stream
Object #M
Process
Object #2
Process
Object #N
ProcessObject #1
ProcessObject #3
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Implementation of
MinOOcad
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Models of
Flowsheet Elements
SLOW
FAST
INTERMEDIATE
0 1 10
Response
t/ Longest Dwell Time
Coarse Ore
Storage
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Dynamic/Multi-Components
Accumulation = Input - Output
+ Generation
Screen
Stream
P80
T
P
( )dt MOut,ij f Mij= - + sdMi,j
MIn,i,j
Particle Size Decreasing
ABAB
BB
AA
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Comminution Objects
- The Ball Mill
Feature 1Visualization
Feature 2Dynamic
PerformanceControl
Feature 3Scale-up/Design
Feature 4Capital/Operating Cost
$$
ManagerComputation
Procedures
Input and Output User Interface
Knowledge
Base
Ball Mill Object
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Comminution Objects
Mine
Truck
Storage
Crushers
Conveyors
Screens
Ball Mill - Pebble Mill
SAG - AG Mills
Sumps
Hydrocyclones
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Simulation Case Study
MinePrimary
Crusher
Primary
Mills
SecondaryMills
BallMill
Coarse Ore
Storage
SAGMILL
SAGMILL
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MinOOcad Flowsheet
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Tool Bar and Property Page
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Property Pages
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Zoom on Property Page
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Outputs
Date Time, hr Feedrate Feed wate Jetwater Mill rpm
6/14/98 18:00 0.00000 2037.9 673.3 75.0 10.01
6/14/98 18:02 0.03333 2010.7 672.4 75.0 10.01
6/14/98 18:04 0.06667 2021.5 673.0 74.9 10.01
6/14/98 18:06 0.10000 2051.2 673.6 74.9 10.01
6/14/98 18:08 0.13333 2080.9 677.6 74.9 10.01
6/14/98 18:10 0.16667 2059.8 690.0 74.9 10.01
6/14/98 18:12 0.20000 2076.0 687.8 74.9 10.016/14/98 18:14 0.23333 2096.1 682.5 74.8 10.01
6/14/98 18:16 0.26667 2116.2 678.1 74.8 10.01
6/14/98 18:18 0.30000 2112.2 679.5 74.8 10.01
6/14/98 18:20 0.33333 2099.1 675.8 74.8 10.01
6/14/98 18:22 0.36667 2095.3 675.5 74.8 10.01
6/14/98 18:24 0.40000 2093.0 665.2 74.7 10.01
6/14/98 18:26 0.43333 2090.6 665.4 74.7 10.01
6/14/98 18:28 0.46667 1507.2 666.8 74.7 10.016/14/98 18:30 0.50000 1663.9 684.5 74.7 10.01
Spreadsheet Graphic
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Base Case - At Steady State
SAG Mill%L=12
Ball Mill
%L=70
0.01
0.10
1.00
10 100 1000 10000 100000 1000000
Particle Size, microns
FractionPassin
g
Mine% L =0
Gyratory% L=0
Predicted
Operating Data
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Dynamic Situations
Simulated
Increase in Powder Factor at Mine
Increase in Truck Haul Time
Decrease in Stockpile Inventory
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Increase in Powder Factor
10000
100000
1000000
0 2 4 6 8 10 12
Time, hr
Mine,Crusherand
StockpileP80,
micro
ns
10
100
1000
SAGandBallMillP80,microns
SAG Mill
Ball Mill
Mine
Stockpile
Crusher
Powder factor increased by 150%
SAG Mill
Ball Mill
Mine
Stockpile
Crusher
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Decrease in Stockpile Inventory
10
100
1000
10000
100000
1000000
2 4 6 8
Time, hr
P80,m
icrons
100
200
300
400
500
Tonnage,mtph
Mine P80
Crusher P80
SAG m ill
tph
Stockpile tph
Ball mill P80
SA G mill P80
Ball Mill P80
SAG Mill P80
Stockpile tph
SAG Mill
tph
Mine P80Crusher P80
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Downstream Impacts
0
200
400
600
800
1000
2 4 6 8
Time, hr
Holdup,
torTonang
e,
tph
0
1000
2000
3000
4000
5000
Power,kw
Stockpile tonnage
SAG mill power
SAG m ill rock tons
SAG mill tonnage
Begin stockpile inventory change
50
75
100
125
150
175
2 4 6 8
Time, hr
P80,micr
ons
22
24
26
28
30
32
%o
fMagnetite
Liberated
Begin change in stockpile
inventory
Ball mill P80
Ball m ill magnetite liberated
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Future Possibilities Operating costs calculated on a minute-to-minute
basis over the entire flowsheet
Enterprise-wide control system capability integrated
into simulator
Incorporating the impact of maintenance usingrealistic wear and replacement models
Embedding into control system software for on-line
decision making
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Conclusions Comminution comprises the most energy intensive and
costly set of unit operations at a mine/mill site.
Opportunities exist to improve "enterprise-wide financial
performance" through understanding and exploiting
dynamic/steady state interactions between comminution
operations. A Windows based generic flowsheet simulator,
MinOOcad, has been developed to allow dynamic
simulation for any number of elements
Advanced comminution models embedded in well
designed software objects can provide realistic simulations
off all flowsheet elements.
Potential uses forMinOOcadare broad and exciting.