Crushing flowsheet simulation: increased productivity and improved ...

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O'BRYAN, K. Crushing flowsheet simulation: Increased productivity and improved flowsheet design. APCOM 87. Proceedings of the Twentieth International Symposium on the Application of Computers and Mathematics in the Mineral Industries. Volume 2: Metallurgy. Johannesburg, SAIMM, 1987. pp. 167 - 178. Crushing Flowsheet Simulation: Increased Productivity and Improved Flowsheet Design K. Q'BRYAN Process Machinery Division, Nordberg Inc., Milwaukee, WI, USA A lO-year program to integrate crushing and screening models into daily flowsheet design practice has proven successful. A Circuit Analysis Program (CAP) is used worldwide to design and evaluate new and existing crushing flowsheets. To gain user acceptance of CAP and maximize effectiveness, model development, simulation flexibility, ease of use, and developing international access are key issues. These issues have been resolved effectively resulting in flowsheet simulations to assist in justifying increased capital investment. CAP is presently utilized in Canada, United States, and South Africa with intentions to expand to Europe and Asia. Introduction A considerable amount of academic research has been conducted to develop accurate models of unit processes in the mineral industries. However, the industrial appli- cation of these models to simulation of plant flowsheets has been limited. In 1983, Nordberg Machinery, a manufacturer of crushing, milling and screening equipment, successfully implemented a computer program for the simulation of crushing and flowsheets. This Circuit screening Analysis worldwide Program (CAP) is utilized and/or for the development analysis of crushing plant flowheets. CAP has enabled Nordberg to improve both worker productivity and the quality of flowsheet design. With the information generated by CAP, customers can be more confident of a given flowsheet's predicted performance. This information can be utilized by the customer to financially justify capital expenditures based on CAP's simulation predictions. cations include: Typical appli- 1. New Flowsheet design 2. Study and modification of existing flow- sheets 3. Plant studies for evaluation of automa- tion potential. The development of CAP encompassed several years, and its successful implemen- tation was a result of resolving problems related to model development, simulation flexibility, ease of use, and international access. The context of this paper will focus on these areas and conclude with a case study of a recent flowsheet design and plant study. Model development The model development is a result of data collected from laboratory tests and field data collected on crushing and screening equipment. A generalized screening model (figure 1) similar to one presented by Karra (1979) has been developed. As shown in figure 1, a screening oversize partition curve is developed from the algorithm: ESTIMATING GRADE DIFFERENTIALS FROM DRILLING RESULTS 167

Transcript of Crushing flowsheet simulation: increased productivity and improved ...

Page 1: Crushing flowsheet simulation: increased productivity and improved ...

O'BRYAN, K. Crushing flowsheet simulation: Increased productivity and improved flowsheet design. APCOM 87. Proceedings of the Twentieth International Symposium on the Application of Computers and Mathematics

in the Mineral Industries. Volume 2: Metallurgy. Johannesburg, SAIMM, 1987. pp. 167 - 178.

Crushing Flowsheet Simulation: Increased Productivity and Improved Flowsheet Design

K. Q'BRYAN

Process Machinery Division, Nordberg Inc., Milwaukee, WI, USA

A lO-year program to integrate crushing and screening models into daily flowsheet design practice has proven successful. A Circuit Analysis Program (CAP) is used worldwide to design and evaluate new and existing crushing flowsheets. To gain user acceptance of CAP and maximize effectiveness, model development, simulation flexibility, ease of use, and developing international access are key issues. These issues have been resolved effectively resulting in flowsheet simulations to assist in justifying increased capital investment. CAP is presently utilized in Canada, United States, and South Africa with intentions

to expand to Europe and Asia.

Introduction

A considerable amount of academic research

has been conducted to develop accurate

models of unit processes in the mineral

industries. However, the industrial appli­

cation of these models to simulation of

plant flowsheets has been limited. In

1983, Nordberg Machinery, a manufacturer of

crushing, milling and screening equipment,

successfully implemented a computer program

for the simulation of crushing and

flowsheets. This Circuit screening

Analysis

worldwide

Program (CAP) is utilized

and/or for the development

analysis of crushing plant flowheets.

CAP has enabled Nordberg to improve both

worker productivity and the quality of

flowsheet design. With the information

generated by CAP, customers can be more

confident of a given flowsheet's predicted

performance. This information can be

utilized by the customer to financially

justify capital expenditures based on CAP's

simulation predictions.

cations include:

Typical appli-

1. New Flowsheet design

2. Study and modification of existing flow­

sheets

3. Plant studies for evaluation of automa-

tion potential.

The development of CAP encompassed

several years, and its successful implemen­

tation was a result of resolving problems

related to model development, simulation

flexibility, ease of use, and international

access. The context of this paper will

focus on these areas and conclude with a

case study of a recent flowsheet design and

plant study.

Model development

The model development is a result of data

collected from laboratory tests and field

data collected on crushing and screening

equipment. A generalized screening model

(figure 1) similar to one presented by

Karra (1979) has been developed. As shown

in figure 1, a screening oversize partition

curve is developed from the algorithm:

ESTIMATING GRADE DIFFERENTIALS FROM DRILLING RESULTS 167

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100

90 OJ

.!:: 80 '" ... OJ .... 0 70

1:1 OJ OJ ... 60 y

00 Q ..- 50 ;..tIJ!lIII'.4I1lII'.4IIi!iY.4Ii!IIT.JIIIIl!r"".4!IIIT,4IJIJII"JiII1IT.4Ii!IITJIfIII!II'..JI!IIlIII":.

eJI 1:1 .• .... 40 ... Q

=-OJ ~ 30 .... == OJ Y 20 ... OJ ~

10

0

.4 .6 .8 1.0 1.2 1.4

FIGURE 1. Normalized oversize position curve for screen model

where: %C i is the oversize partition

coefficient,

Di is the geometric mean particle

size

d50 is the mean particle size

where 50% passes

Kl is a statistically determined

constant related to the designed

screen dynamics.

Each size gradation is separated via the

composition of this partition curve. The

screen model allows CAP to account for

screen inefficiency which varies depending

on the amount of near size material, fine­

ness of separation, and surface character-

istics of the material. Screens are sized

relative to internationally accepted screen

sizing practice.

Field data has been collected to

determine the performance of Gyratory,

Cone, Gyradisc, Jaw and Impact crushers.

CAP's crushing models enable simulation of

168

Feed Data

~ Crusher Model

PARAMETERS

Type of Machine

Gap/Setting

Cham ber Design

Crushing Characteristics of Material

Production Data

FIGURE 2. Generalized concept of crushing model used by CAP

all these crushing devices. _.As shown in

figure 2, the crushing performance of a

given machine is determined by the user­

selected liner, crusher setting, throw, and

type of crusher. Connected horsepower,

speed, and throw are generally assumed

constant for a given size and type of

machine. Provisions have been made in the

program to

agglomeration

provided the

include

device

any

in

crushing or

the circuit

gradat ion and- production

characteristics of that device are known.

The crushing and screening models within

CAP provide satisfactory estimates of

crushing and screening performance. The

most confident model predictions are based

on actual field performance of existing

equipment for a given material. Model

development for CAP will continue as addi­

tional data is collected.

Simulation flexibility

Lack of simulation flexibility is a common

problem of many commercially available

simulation packages. Customers, particu-

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1ar1y those customers producing aggregate

products, utilize a wide variety of flow-

sheet configurations. In addition, two

plants producing identical products can be

designed with widely varying f10wsheets.

The speed with which a f10wsheet can be

simulated enables a user to examine several

f10wsheet options. The final design is

determined by economics, company practice,

individual preference, and technical per-

formance. For successful f10wsheet simu-

1ation of crushing and screening circuits,

CAP's simulation flexibility is an absolute

requi rement.

Simulation flexibility is the principal

technical strength of CAP. With this flow­

sheet simulator users, in a matter of

minutes for each simulation, can conduct a

performance analysis of changing operating

conditions.

flowsheet

CAP is used for 99% of all

analysis by North American

users. Typical examples include:

1. The increased production from higher

performance crushers.

2. The effect of modifying screen perfor­

mance on crusher loading.

3. Reduced circulating loads from tighter

crusher settings.

4. Finer products from tighter crusher

settings.

S. Creating different products by modifying

material flows.

6. Identification of f10wsheet bottlenecks.

7. Effect of material crushing character­

istics on circuit performance.

A crushing/screening f10wsheet can be

simulated by dividing the f10wsheet into

simulation stages. Each stage can contain

1-100 identical crushers and 1-100

identical screens. A maximum of eight

s imu1at ion s toages are allowed. Each stage

has the ability to simulate splitters for

splitting material flows into multiple

streams. Material flows can be transferred

directly from stage to stage, deposited in

one of eight available product bins or nine

available surge bins, or recircu1ated to a

previously simulated component. By

combining surge and product bins, a total

of 17 different final products can be

created.

Ease of use

The potential users of CAP are application

and sales engineers. Many of these users

have minimal experience with computers or

computer models. Successful development of

CAP requires user-friendly input and error

prevention procedures. Early efforts to

implement these models at Nordberg failed

mainly due to difficult execution proc­

edures.

Data processing experts were consulted to

develop easier to use input and output

Create Composite Data COBOL Software File

Simulate Flowsheet Performance

FORTRAN Models

Edit Final Output

FIGURE 3. Final structure of CAP for USA users. COBOL programs handle input/output and FORTRAN program models flowsheet

ESTIMA TING GRADE DIFFERENTIALS FROM DRILLING RESULTS 169

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formats. CAP was transferred from a time-

sharing CDC mainframe to Nordberg's

Milwaukee IBM mainframe. The Milwaukee

mainframe's VMSP system provided full­

screen edit capabilities for creating data

files. The data processing staff developed

COBOL software for data handling and error

checking.

With the use of full-screen editing and

the development of error checking COBOL

software, the final structure (figure 3) of

CAP was completed. These enhancements

transformed CAP from TTY batch operation to

a full-screen interactive program.

result, user acceptance was achieved.

International access

As a

After CAP had been successfully implemented

in Milwaukee, a study was conducted

regarding international access to CAP. Two

locations, Guelph, Canada and Johannesburg,

South Africa agreed to test and implement

CAP.

A review of problems associated with

international access identified key areas

of concern, specifically:

1. Program security.

2. Establishing communication links.

3. Economic costs.

4. Ease of use and troubleshooting.

As international access became a

priority, maintaining the security of CAP

became the key issue. Recent developments

in personal computer tachnology made

available the possibility of converting the

entire software for execution on a PC.

However, maintaining program security would

be almost impossible with the current

technology. The PC option was quickly

rejected.

The final choice for maintaining the

maximum program security became establish-

170

ing telecommunications links to a central­

ized time-sharing mainframe. International

users would be provided execution~only

acess through these telecommunication

links. International telecommunication

links were established through TYMNET in

North America, SAPONET in South Africa and

DATAPAC in Canada.

Full screen access of CAP was established

in Canada and South Africa, however,

several deficiencies were identified:

1. High cost,

2. Hardcopy transmittal was of poor

quality,

3. Inability to edit CAP output.

The high transmission costs resulted from

transferring the peripheral data associated

with the full-screen mode. This problem

was especially critical during data input

when 90% of the data transmitted was

in nature. Transmission of descriptive

only data

simulator

required for the flowsheet

would reduce both data trans-

mission and execution costs.

Downloading of data to a remote location

via full-screen mode was unsatisfactory.

CAP outputs were difficult to read and

impossible to edit.

discussions with

achievable.

Use of CAP outputs in

customers was not

A second study determined that the above

problems experienced by international users

could be solved by converting the communi­

cations link from full-screen mode to TTY

mode. In the TTY mode, a personal computer

with a full-screen editor 1s utilized for

executing the COBOL input programs and for

editing the simulation output. The

simulation/data transfer environment for

international users is depicted in figure

4.

With the transition of using a personal

METALLURGY: MODELLING

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FIGURE 4. International users' simulation/data transfer environment. Personal computer acts as an intelligent terminal for input data development and output editing

computer as an intelligent terminal,

communications and execution costs were

reduced an average of 75%. Subsequent

enhancements include 1) on-line help

facility, 2) File handling utility, and 3)

Electronic mail

problems.

system for reporting

Case study: 450 tph aggregate plant

A North American consulting company is

responsible for the design and construction

of a basalt aggregate plant. Production

specifications and requirements forwarded

to Nordberg Application Engineers included:

375 Metric Tons per hour (MTPH) of

32mm by 0 blend.

40 Metric Tons per hour (MTPH) of

17mm by 0 blend.

35 Metric Tons per hour (MTPH) of

17mm by 10 mesh blend.

The initial request from the consultant

was for quotation of a Jaw/Cone crushing

plant to produce the desired products.

Earlier manual estimates by competitive

manufacturers indicated that the plant

production could be met with one 1109 Jaw

Crusher and two 1.3 meter cone crushers.

To fully determine the equipment required

to meet product specifications, CAP was

utilized to determine plant performance

under two options, specifically:

Option 1. One 1109 VB Jaw Crusher

Two 1560 Omnicone Cone Crushers

Base. design on 90 to 85%

screening efficenicy.

(see flowsheet in figure 5)

Option 2. One 1109 VB Jaw Crusher

Two 1560 Omnicone Cone Crushers

'One 48 inch (1.2 meter) Nordberg

Gyradisc

Base design on 90 to 85%

screening efficiency. (see

flowsheet in figure 6)

ESTIMATING GRADE DIFFERENTIALS FROM DRILLING RESULTS 171

Page 6: Crushing flowsheet simulation: increased productivity and improved ...

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Page 7: Crushing flowsheet simulation: increased productivity and improved ...

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Page 8: Crushing flowsheet simulation: increased productivity and improved ...

Option 1 was simulated at the request of

the consulting contractor. Option 2 was

simulated as the Nordberg recommended

flowsheet design to guarantee meeting the

customer's requirements. The simulated

performance comparison of the two options

is outlined in Tables I and I!. The CAP

simulation of the quaternary stage for

option 2 is presented in the attached

Appendix.

The data in Table I indicates total plant

productivity and compares individual

crusher performance for options 1 and 2.

This data summary clearly indicates that

option 2, the quaternary crushing circuit,

is required to meet the customer's

production requirements. Option 1 could

not produce enough fine aggregate to meet

product specifications and achieved a

maximum capacity of 425 TPH. Option 2,

with the additional quaternary crushing

stage, met the customers's production

TABLE I

174

Production Comparison on Flowsheet Simulation Options. Option 1 is a three­stage crushing circuit with a flowsheet as shown in figure 5. Option 2 is a four-stage crushing circuit with a flowsheet as shown in figure 6.

Run of Quarry Feedrate:

Primary Scalper Performance Scalper Oversize (635mm x 100mm): Scalper Undersize (-200mm x Omm):

VB 1109 Jaw Crusher Performance Closed Side Setting: Total Feedrate: 80% passing of product: % of Full Load Capacity:

Option 1

425 TPH

277 TPH 148 TPH

155 mm 277 TPH 174 mm

99 %

1560 Omnicone Cone Crusher Performance (Secondary) Closed Side Setting: New Feedrate: Total Feedrate: 80% passing of Product: % of Full Load Capacity:

1560 Omnicone Cone Crusher Performance (Tertiary) Closed Side Setting: New Feedrate: Total Feedrate: 80% passing of Product: % of Full Load Capacity:

48 INCH GYRADISC Performance (Quaternary) Closed Side Setting: New Feedrate: Total Feedrate: 80% passing of Product: % of Full Load Capacity:

Plant Production Specified Products

32mm by 0 blend: 17mm by 0 blend: 17mm by 10 mesh blend:

30 mm 296 TPH 313 TPH

37 mm 88 %

13 mm 166 TPH 238 TPH

17 mm 97 %

387 TPH o TPH

38 TPH

Total 425 TPH

Option 2

450 TPH

294 TPH 156 TPH

165 mm 294 TPH 186 mm

98%

38 mm 317 TPH 374 TPH

48 mm 98 %

13 mm 177 TPH 220 TPH 17 mm

95 %

13 mm 48 TPH 93 TPH

8.4 mm 70 %

378 TPH 34 TPH 38 TPH

450 TPH

METALLURGY: MODELLING

fi

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requirement with extra capacity to produce

additional cubical fine aggregates.

In this case study, the use of a Circuit

Analysis Program had distinct advantages.

First, CAP simulations enabled Nordberg to

identify the absolute requirement for 1.5

meter cone crushers rather than 1.3 meter

cone crushers originally proposed. As a

result, the customer could be assured of

meeting his plant production objectives.

Second, the entire quotation process

including examination of several flowsheet

options was completed in less than eight

hours. A similar analysis without a

Circuit Analysis Program would have

required several days of work with a lower

confidence level in final plant perform-

ance.

TABLE II

Screening Performance Comparison of Flowsheet Simulation Options. Option 1 is a three-stage crushing circuit with a flowsheet as shown in figure 5. Option 2 is a four-stage crushing circuit with a flowsheet as shown in figure 6.

Run of Quarry Feedrate

Primary Scalper Performance: Scalper Oversize (635mm x 100mm): Scalper Undersize (-200mm x Omm):

Secondary Screening Performance: Deck One

Mesh Opening Screening Efficiency Area Required

Deck Two Mesh Opening Screening Efficiency Area Required

Deck Three Mesh Opening Screening Efficiency Area Required

Tertiary Screening Performance: Deck One

Mesh Opening Screening Efficiency Area Required

Deck Two Mesh Opening Screening Efficiency Area Required

Deck Three 88 % Mesh Opening Screening Efficiency Area Required

Quaternary Screening Performance: Deck One

Mesh Opening Screening Efficiency Area Required

Deck Two Mesh Opening Screening Efficiency Area Required

Option 1 425 TPH

277 TPH 148 TPH

100 mm 95 %

5.7 m2

63 mm 92 %

6.9 m2

32 mm 89 %

11.8 m2

17 mm 84 %

10.8 m2

9.5 mm 83 %

6.5 m2

4.7 mm 88 %

6.5 m2

ESTIMATING GRADE DIFFERENTIALS FROM DRILLING RESULTS

Option 2 450 TPH

294 TPH 156 TPH

100 mm 95 %

6.8 m2

63 mm 89 %

8.8 m2

32 mm 90 %

12.6 m2

17 mm 86 %

11.4 m2

9.5 mm 83 %

8.0 m2

4.7 mm 88 %

6.7 m2

6mm 94 %

4.1 m2

3.3 mm 91 %

4.5 m2

175

Page 10: Crushing flowsheet simulation: increased productivity and improved ...

Conclusions The successful implementation of computer

models in the industrial environment was

achieved through addressing user needs.

The program's simulation flexibility

coupled with its ease of use has helped CAP

gain a wide acceptance. As a result, this

flowsheet simulation technology is being

utilized on a daily basis for better

flowsheet design.

CAP's worldwide implementation was

accomplished while meeting security and

cost-effectiveness considerations. The key

roles of international telecommunications

networks <;lnd personal computers acting as

intelligent terminals enabled preservation

of key features and allowed additional

enhancements.

CAP is presently being utilized in the

United States, Canada and South Africa.

Applications include plant studies,

flowsheet design, and process control

evaluation. A future objective is to

extend CAP's use to Brazil, Europe and

Australia.

Note CAP (Circuit Analysis Program) is

protected

federal

by United

copyright

States

law.

Reproduction and/or use of CAP

without the express written

permission of Rexnord Inc. is

prohibited.

Reference

Karra, V .K. , "Development of a Model for

Predicting the Screening Performance of a

Vibrating Screen", CIM Bulletin, April,

1979.

Appendix: ACAP simulation output of quaternary crushing circuit

DATE - 06/25/87 TIME - 09:06 P AGE 10

176

STAGE #4 CRUSHING STAGE CONTAINS ( 1) 48 INCH GYRADISC CRUSHER

C R U SHE R SET U P

SETTING = 1.30 CM. LINER TYPE=FINE CIRCUITRY =CLOSED

PRODUCT ANALYSIS

(CM. )

1. 30 .95 .70 .60 .47

6M 10M 14M

P80 =

MATERIAL PASSING (PERCT)

100.0 89.0 74.5 68.0 59.0 46.1 36.2 28.0

.84 CENTIMETERS.

I N D I V I D U A L C R U S H E R C R U S H E R C A P A C I T Y I N D I C E S ..................... . .................. NEW FEED = 48 TPH CAPACITY INDEX= 70% TOTAL FEED= 93 TPH MAX. FEED = 132

PRIMARY DESTN: STAGE #4 (S) AMOUNT: 93 ( TPH)

.C R U SHE R DES TIN A T ION S

METALLURGY: MODELLING

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DATE - 06/25/87 TIME - 09:06 P AGE 11

SCREEN SIZING AND PERFORMANCE ANALYSIS --- STAGE #4 ***************************************************

THEORETICAL AREA REQUIRED.

DECK

1 2

BELOW IS A TABLE GIVING THE SCREEN SIZING FACTORS USED TO DETERMINE THE THEORETICAL AREA OF THIS SCREEN. DEFINITION OF TERMS:

OPENING CM.

-------.600 .333

"OPENING" - EFFECTIVE OPENING OF SCREEN MESH. "A" - STPH PASSING A SQ. FT. OF SCREEN SURFACE. "B" - PERCENT OF OVERSIZE IN FEED TO DECK FACTOR. "c" - PERCENT HALF SIZE IN FEED TO DECK FACTOR. "D" - DECK LOCATION FACTOR. "E" - WET SCREENING FACTOR. "F" - MATERIAL WEIGHT FACTOR. "G" - SCREEN SURFACE OPEN AREA FACTOR. "H" - SHAPE OF SURFACE OPENING FACTOR. "I" - SCREEN SLOPE FACTOR.

"TUST" - THEORETICAL UNDERSIZE TONNAGE. "AREA" - THEORETICAL AREA REQUIRED.

----------SCREEN SIZING FACTORS--------A B C D E F G H I

1. 03 1. 22 1. 27 1. 00 1. 00 1. 00 1. 00 1. 00 1. 00 .72 1. 21 1. 25 0.90 1. 00 1. 00 1. 00 1. 00 1. 00

TUST MTPH

-------63.0 42.7

AREA SQ. M. ------

4.1 4.5

A 1.2 X 3.7 METER 2-DECK SCREEN SELECTED FOR THE APPLICATION

DECK#

1 2

FEED

93 58

OVERSZ

35 19

UNDRSZ

58 39

EFFICY(%)

92 91

DBF

2.4 1.6

ESTIMATING GRADE DIFFERENTIALS FROM DRILLING RESULTS

DBD

.9

.5

MAX-DBD

2.4 1.3

177

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DATE - 06/25/87 TIME - 09:06 P AGE 12

STAGE #4 SCREENING STAGE CONTAINS 1 SCREEN(S) WITH 2 DECK(S).

NEW FEED 48 TOTAL FEED 93 -------------- --------- --------- ---------SCREENING DECK #1 DECK #2 DECK #2 PARAMETERS OVERSIZE OVERSIZE UNDERSIZE -------------- --------- --------- ---------OPENING (CM. ) .600 .333 TONNAGE ( TPH) 35 19 39 PROBABILITY(%) 90 90 EFFICIENCY (% ) 91 90

FEED SCREEN SCREEN SCREEN ANALYSIS PRODUCT PRODUCT PRODUCT -------------- --------- --------- ---------

PRCT PRCT PRCT PRCT INCH MM PASS PASS PASS PASS

.512 13 100.0 100

.374 9 89.0 71

.276 7.0 74.5 32

.236 6.0 68.0 15 100

.185 4.7 59.0 4 76 6M 3.3 46.1 0 21 100 8M 2.4 36.2 3 85

10M 1.7 28.0 0 67 14M 1.2 21. 8 52 20M .8 17 .1 41 28M .6 14.2 34 35M .4 11. 8 28 48M .3 10.2 24 65M .2 8.3 20

-------------- --------- --------- ---------

.. S P LIT S C R E E N ANALySIS ....... .

D E C K # 1 D E C K # 2 D E C K # 2 o V E R S Z o V E R S Z U N D R S Z ------------ ------------ ------------

PRIMARY DESTN: STAGE #4 (C) STAGE #4 ( C) STOCK BIN(3) AMOUNT: 35 ( TPH) 10 ( TPH) 12 ( TPH)

SPLIT 1 DESTN: STOCK BIN(3) STOCK BIN(l) AMOUNT: 10 ( TPH) 27 ( TPH)

------------ ------------ ------------

178 METALLURGY: MODELLING