Simulation of an Underground Haulage System, Renström ...1026217/FULLTEXT02.pdfTitle: Simulation of...

MASTER'S THESIS

Simulation of an Underground HaulageSystem, Renström Mine, Boliden Mineral

Nurnihal Fjellström

Master of ScienceCivil Engineering

Luleå University of TechnologyDepartment o Civil, Environmental and Natural Resources Engineering

Title: Simulation of an underground haulage system, Renström Mine, Boliden

Mineral

Date 7 Juni 2011

Level and category Master’s Thesis, Engineering, 30ECTS

Key words Haulage simulation, mine truck, highway truck,

Renström, Renströmsgruvan, cost, transportation,

underground mine

Author Nurnihal Fjellström, Mining Engineer,

Boliden Mineral AB

Telephone: +46 910 77 41 36

E-post: [email protected]

School Lulea University of Technology (LTU)

Mining and Geotechnical Engineering

Company Boliden Mineral AB, SWEDEN


Supervisor Arne Renström (Boliden Mineral AB)

E-post: Arne.Renströ[email protected]

Examiner: Jenny Greberg (Lulea University of Technology)


2

PREFACE

This report has been written as a Master’s Thesis and the study has been carried out at

Technology Department, Boliden Mineral AB, and Sweden. The thesis is a part of a

simulation project of Renström mine which is the second step of time studies conducted

by TG section in Boliden Mineral AB in Renström mine.

In the thesis, transportation cost of ore and waste material to the crusher and backfilling

rooms in the underground Renström mine are determined by using the software package

called AutoMod simulation program.

I first would like to thank to my manager, Craig Griffiths for giving me support both

during my master studies and master thesis.

I also would like to thank Arne Renström for all support he has given me since we have

met and worked together.

I would like to thank my supervisor Jenny Greberg for the interest she has shown to this

study and all the guidance.

The contribution, help and support of Linus Bördin and Niels Glahamheden from ÅF is

gratefully acknowledged.

I want to thank my friend Nils Johansson for his kindness, help and support.

Finally, I would like to thank my dear husband, Peter Fjellström, for all the support and

encouragement he has given me during all these years.

Skellefteå, 7 Juni 2011

Nurnihal Fjellström

3

ABSTRACT

The scope of the simulation project is to simulate different alternatives for the transport of

ore and waste rock to the backfilling room and to the crusher in the mine and then

determine the transportation cost for respective alternatives and finally choose the best

option with the lowest transportation cost.

In Renström mine, the truck fleet consists of 3 highway trucks with an addition of 1 mine

truck due to test driving reasons before purchase. Renström mine has a demand for a

decrease in transportation costs and the number of break downs of the trucks. By

simulating different transportation alternatives and comparing the costs, it is easy and fast

to make decisions about the production system.

In order to achieve this goal, a literature study on simulation and the application of

simulation on mining industry has been conducted. All the necessary input data were

collected in activity studies in Renström mine in September and October period, 2010.

With the support and help of ÅF consult, a simulation model of Renström mine was

created using AutoMod software. AutoMod is a simulation program which can simulate

all the processes not only in the mine but also in other industries. The reason why

AutoMod software was selected as a simulation program was because it was used for short

term scheduling in Boliden Mineral AB in 1999 - 2000.

Major findings from the model are that the mine truck is 23% more effective than the

highway trucks, the usage of only highway trucks are 34% more expensive than the usage

of only mine trucks and for combination alternatives, if most of the transportation is done

by mine trucks instead of highway trucks, the transportation cost per tonne is decreasing

by 10-20%.

In conclusion, after all analyses were done, 3 mine trucks with one reserve truck have

been selected as the cheapest feasible alternative for the mine. To sum up, it is possible to

build a simulation model of an underground mine for transportation system to determine

the most productive and the cheapest option. Moreover, the simulation model of the

underground haulage system of Renström mine can also be used to analyse the influence

of different transportation strategies on mine production in the future.

4

SAMMANFATTNING

Den här rapporten är baserad på resultaten från en simulering av transport i Boliden

Mineral ABs Renströmsgruva.

Omfattningen av examensarbetet är att simulera gråberg och malm transport till

återfyllningsrum och till krossen och sedan beräkna transportkostnader för att slutligen

välja det bästa alternativet med lägst transportkostnader.

I Renströmsgruvan används 3 lastbilar tillsammans med en extra bergtruck som används

för provkörning innan inköp. Renström har krav på en minskning av transportkostnader

och störningar i produktionen. Genom att simulera olika transport alternativ och jämföra

kostnaderna, är det lätt och snabbt att fatta beslut om produktionssystemet.

En litteraturstudie om simulering och tillämpning av simulering gruvindustrin har

genomförts. Alla nödvändiga indata har samlats in vid aktivitetsstudier i Renström under

september och oktober period, 2010. Med stöd och hjälp av ÅF konsult, skapades en

simuleringsmodell av Renström i AutoMod programvara. AutoMod är ett

simuleringsprogram som kan används för att simulera alla processer inte bara i gruvan

men även i andra branscher. Anledningen varför AutoMod valdes ut är på grund av det

användes för kortsiktiga planering i Boliden Mineral AB mellan 1999 och 2000.

Viktiga resultat från modellen är att bergtruckar är 23 % mer effektiva än lastbilar,

användningen av endast lastbilar är 34 % dyrare än användning av bara bergtruckar och

för kombinations alternativ, om större delen av transporten sker med bergtruckar i stället

för lastbilar minskar transportkostnaderna per ton från 10 till 20 %.

Sammanfattningsvis, efter alla analyser genomförts, har 3 bergtruckar med en reserv bil

valts ut som det billigaste alternativet för gruvan. Det är möjligt att bygga en simulerings

modell för en underjordsgruva för att bestämma det mest produktiva och billigaste

alternativet för transport. Dessutom kan simuleringsmodellen över transport systemet för

Renströmsgruvan också användas för att se inverkan av olika transport strategier på

gruvproduktion i framtiden.

5

TABLE OF CONTENTS

PREFACE ............................................................................................................................ 2

ABSTRACT ......................................................................................................................... 3

SAMMANFATTNING ........................................................................................................ 4

TABLE OF CONTENTS ..................................................................................................... 5

LIST OF FIGURES .............................................................................................................. 7

LIST OF TABLES ............................................................................................................... 8

1. INTRODUCTION ................................................................................................... 10

1.1 Introduction and scope of work ........................................................................... 10

1.2 Boliden Mineral AB ............................................................................................ 12

1.2.1 Background .................................................................................................. 12

1.2.2 Skellefte field ............................................................................................... 12

1.2.3 Renström Mine ............................................................................................. 13

1.2.4 Mining Methods ........................................................................................... 15

1.2.5 The Mining Sequence for Ore Extraction and Backfilling ........................... 16

1.2.6 Transport of ore and waste ........................................................................... 17

2 METHODOLOGY ...................................................................................................... 19

3 SIMULATION THEORY ........................................................................................... 20

3.1 Simulation in the mining industry ....................................................................... 20

3.2 Simulation benefits and disadvantages ................................................................ 22

3.3 Simulation Tools .................................................................................................. 22

3.4 AutoMod .............................................................................................................. 23

3.5 The Simulation Process ....................................................................................... 24

6

4 DEVELOPMENT OF the SIMULATION MODEL ................................................... 28

4.1 Excel Interface ..................................................................................................... 28

4.2 Verification .......................................................................................................... 29

4.3 Validation ............................................................................................................ 30

4.4 Sensitivity of the simulation model ..................................................................... 30

5 SIMULATION RUNS AND RESULTS ..................................................................... 34

6 DISCUSSION AND CONCLUSION ......................................................................... 44

7 FUTURE WORK ......................................................................................................... 46

REFERENCES ................................................................................................................... 47

APPENDIX I ...................................................................................................................... 50

Details on the Simulation Model ........................................................................................ 50

1. Scheduled hours and Out of plan............................................................................. 51

2. Working hours ......................................................................................................... 52

3. Delay Time .............................................................................................................. 53

4. Idle Time ................................................................................................................. 54

5. Scheduled and unscheduled maintenance time ....................................................... 54

6. Number of vehicles and capacities .......................................................................... 54

7. Driving speed for mine/highway trucks .................................................................. 55

8. Loading, Dumping, Meeting and Manoeuvre times ................................................ 55

9. Blasts and Dumping places (crusher or backfilling room) ...................................... 57

10. Process Flow for each machine in the mine ........................................................ 57

APPENDIX II ..................................................................................................................... 59

Input data for simulation model ......................................................................................... 59

APPENDIX III ................................................................................................................... 69

Output data from simulation model .................................................................................... 69

7

APPENDIX IV ................................................................................................................... 74

Flowchart of the activities in Renström mine and the logic behind the model in AutoMod

............................................................................................................................................ 74

LIST OF FIGURES

Figure 1: The view over Skellefte field .............................................................................. 13

Figure 2: The view over Renström mine ............................................................................ 15

Figure 3: The sequence of activities in the mine ................................................................ 17

Figure 4: The life cycle of a simulation study (Balci, O., 1990) ........................................ 26

Figure 5: Steps in a Simulation study (Groumpos, P. & Merkuryev, Y.) .......................... 27

Figure 6: Sensitivity analysis for Highway truck (20% over and under estimations) ........ 32

Figure 7: Sensitivity analysis for Mine truck (20% over and under estimations) .............. 33

Figure 8: Different activities during working hours (source: Caterpillar) ......................... 51

Figure 9: The view over loading activity ........................................................................... 56

Figure 10: The view over activities displayed in a Gantt chart (Gantt Browser) ............... 70

Figure 11: Vehicles sheet in excel ..................................................................................... 71

Figure 12: Scheduled and Actual blasting dates for each blast (Cyclelog sheet) ............... 72

Figure 13: The vehicles sheet in excel (the values are not representative) ........................ 73

8

LIST OF TABLES

Table 1: The amount of probable, indicated and inferred resources in Renström ............. 14

Table 2: The grade of the ore for reserve, indicated resource and inferred resource in

Renström ............................................................................................................................ 14

Table 3: The usage of each mining methods according to the years in Renström mine .... 15

Table 4: Parameters and their influence on cost calculation for Highway and Mine trucks

............................................................................................................................................ 31

Table 5: Simulation runs with only highway trucks ........................................................... 35

Table 6: Simulation runs with only mine trucks ................................................................ 36

Table 7: Simulation of combination (both mine trucks and highway trucks) without

reserve truck ....................................................................................................................... 37

Table 8: Simulation runs of combination with reserve truck ............................................. 38

Table 9: Simulation runs with productions higher than 76 500 tonne and transportation

cost ratios for each option .................................................................................................. 39

Table 10: Risky options ...................................................................................................... 41

Table 11: Transportation options that meet the production target of 76 500 tonnes ......... 42

Table 12: Calculation table for the cost of transported ore ............................................... 43

Table 13: The corresponding start points of the machines ................................................. 53

Table 14: The list of activities in the mine ......................................................................... 60

Table 15: Working hours in the mine for early, late and night shift .................................. 61

Table 16: Blasting and Ventilation hours for each shift team ............................................ 61

Table 17: Different cycle types and their durations (Cycles sheet in excel) ...................... 62

Table 18: The example view over machine properties table in excel for AutoMod

(Machines sheet in excel) ................................................................................................... 63

9

Table 19: Amount of machines in reality and in AutoMod ............................................... 64

Table 20: Detailed activity times in Renström mine (Shift sheet in excel) ........................ 65

Table 21: Average activity duration for haulage by Highway truck and Mine truck......... 66

Table 22: Ore and waste transportation schedule according to date and room (Blasting

sheet in excel) ..................................................................................................................... 66

Table 23: Backfilling rooms (Backfilling sheet in excel) ................................................. 67

Table 24: Loading, dumping and meeting duration for haulage vehicle (General Input

sheet in excel) ..................................................................................................................... 68

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1. INTRODUCTION

1.1 Introduction and scope of work

In recent years, there has been an increasing demand for minerals and metals in the world.

Many mining companies are trying to find new innovative equipment which can increase

the productivity by reducing labour costs and supplying safer and cleaner working

conditions.

The scope of the simulation project is to simulate different alternatives for the transport of

ore and waste rock to the backfilling room and to the crusher in the mine and then

determine the transportation cost for respective alternatives and finally choose the best

option with the lowest transportation cost.

In this thesis work, transportation cost of ore and waste material to the crusher and

backfilling rooms in the underground Renström mine are determined using the software

package called AutoMod simulation program. A simulation model of haulage

transportation system of Renström Mine is described. With the help of the software,

maintenance and repair costs, fuel consumption cost and tire wear of the trucks etc. in a

certain wished period for different haulage system alternatives can be determined by the

user.

Today in Renström mine, highway trucks are being used for the haulage transportation of

ore and waste material in combination with one mine truck. Mine trucks are not usually

being used in Renström so most of the transportation is done with highway trucks.

However, there is only one mine truck for test driving before purchase. The main

consideration in Renström mine is to take a decision about how many and which type of

trucks that should be used for the transportation of ore and waste rock in order to decrease

the transportation cost as much as possible.

An activity study was conducted in Renström mine in September and October 2010

regarding the same issue (highway truck versus mine truck). This study only aimed at

investigating the transportation cost of the existing system.

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However, the management of Renström mine wants to identify other possible

transportation options and to evaluate them in order to choose the best and the cheapest

option that can handle the planned production.

The management of Renström mine wants to know the lowest transportation costs

according to the following scenarios:

If only highway trucks are used

If only mine trucks are used

If a combination of both types are used.

In addition, the best option is the one that can handle the existing planned production for a

given period at the lowest cost.

Renström mine has been simulated in 1999 using AutoMod simulation program but the

same model could not be used due to the many changes since 1999 in the layout of mine

such as backfilling rooms, new levels, new production rooms and transportation style.

Therefore, a new layout model of the mine has been built by using Microstation computer

aided design (CAD) program. In Microstation, the transportation route between stopes and

crusher/backfilling room and meeting points have been drawn and each stope for ore and

waste, crusher and backfilling rooms are shown as stations according to the production

plan valid between 1st September and 31

st October. In this period, activity studies were

conducted to gather the input data for the model, thus, the same period is also selected as a

simulation period to ease the verification and validation stages. In order to verify that the

simulation model is working properly and reflecting the reality, the results obtained by the

simulation model and the results from the activity study have been compared. Due to the

reason that AutoMod program already exists in Boliden Mineral, the new model is again

created in AutoMod.

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1.2 Boliden Mineral AB

1.2.1 Background

Boliden Mineral AB started its activities in 1931 and has grown to be a mining, smelting

and recycling company focusing on firstly copper and zinc and secondly gold, lead and

silver production. The company has 4400 employees and the turnover amounts to 28

billion SEK annually. Boliden Mineral AB has its mines in Sweden and Ireland and

smelters are located in Norway, Sweden and Finland.

Boliden has the third rank on the largest copper metals and zinc metals supplier in Europe.

In addition, the company shares are listed on the Stockholm (Sweden) stock exchange and

Toronto (Canada) stock exchange.

For more information please visit: www.boliden.com

1.2.2 Skellefte field

In Skellefte field, Boliden Mineral AB owns and operates 3 mines (see Figure 1); two

underground mines (Renström and Kristineberg mine) and one open pit mine (Maurliden).

Beside this, there is also a concentrator and a gold leaching plant. The mines located at

this region have sulphide ores which contains copper, zinc, lead, gold and silver.

13

Source: Boliden Mineral AB

Figure 1: The view over Skellefte field

1.2.3 Renström Mine

The production in Renström Mine started in 1952 and complex ore containing zinc,

copper, lead, gold and silver has been mined. Renström mine is the deepest mine in

Sweden (1300 m below surface in January 2010). The yearly ore production in the mine is

approximately 250 000 tonnes and 10, 3 million tonnes of ore has been mined (by the end

of 2008). There are 105 employees working in Renström mine (2009). The mining method

is cut and fill mining method.

Renström mine is combined to Petiknas mine with a 2.5 km long drift at 800 level (see

Figure 2). Mineralization continues down to 1700 meter and the mine has a good future

potential (see Table 1 and 2).

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Ore bodies Probable ore Indicated and inferred resource

Main ore 288 ktonnes 511 ktonnes

Simon 550 ktonnes 1717 ktonnes

Vilma 235 ktonnes 195 ktonnes

Julia 180 ktonnes 410 ktonnes

Fingal 180 ktonnes

Aina 170 ktonnes


Table 1: The amount of probable, indicated and inferred resources in Renström

In Renström mine, 1060 ktonnes has already been mined out.

Au (g/t) Ag (g/t) Cu % Zn % Pb % S %

Reserves 2.6 161 0.5 7.6 1.5 12

Indicated resource 2.6 285 0.5 8,2 2.1 18

Inferred resource 2.2 155 0.8 5.7 1.4 12

Sill pillars 3.0 161 1 8 2 14


Table 2: The grade of the ore for reserve, indicated resource and inferred resource in Renström

15


Figure 2: The view over Renström mine

1.2.4 Mining Methods

Most of the ore is mined using the cut and fill method, with 5m slices (see Table 3).

Mined out stopes are backfilled with waste from the development.

The sill pillars between the stopes are mined using a vertical retreat method, locally

known as opping.

METHOD 2006 2007 2008 2009 2010 2011

Cut and fill 96% 96% 96% 99% 100% 94%

Vertical retreat

(opping)

4% - 1% - - 5%

Benching - 4% 4% 1% - 1%


Table 3: The usage of each mining methods according to the years in Renström mine

16

1.2.5 The Mining Sequence for Ore Extraction and Backfilling

According to Figure 3, the first step to extract ore begins with diamond drilling. The

sample rock obtained is sent to the laboratories to be analysed by geologist in order to

decide the direction of the highest mineral concentration of the mineralization. The mine

planning department decides how the ore body will be mined according to the information

from the geology department. The face to be blasted is drilled by drilling machines

according to the production plan.

The face which has been drilled is charged with explosives and blasting caps are placed

into the boreholes. The blasting is done using a surface remote firing system after all the

workers have left the mine during shift change. During blasting all staff must leave the

mine. After each blasting, ventilation is done to remove the harmful gases and dust and to

supply fresh air to the workers. After ventilation is completed the blasted rock is watered

before the loading operation starts in order to depress the dust and the unexploded

explosives in the blast. The ore is loaded onto the trucks by front end loader and

transported to the crusher located at 800 m level. The waste rock is used as backfilling

material together with sand.

After all the blasted ore has been loaded onto the trucks and sent to the crusher, scaling

machine checks the roof and the walls to prevent loose rock fall. After scaling, primary

cleaning is done to remove the rocks that have been removed by the scaler from the roof

and the walls. In order to reinforce the walls and the roof of the stope, shotcreting is

performed. In the concrete, there are small thin metal pieces to make the concrete capture

the surface better and to increase the toughness of the concrete. After the concrete has

dried, in other words when the shotcrete has settled down, the roof and the wall is ready to

be drilled for the cement or resin bolting. The stopes that have already been mined out are

backfilled with waste rock or sand. The sand used as backfilling material comes from the

enrichment plant in Boliden.

After the crushed ore is sent to the skip by the conveyor belts it is hoisted to the surface /

headframe by the skip (capacity of 4.5 ton per skip and 90 ton per hour). The trucks

transport the ore to the process plant in Boliden for the further handling.

17

Figure 3: The sequence of activities in the mine

1.2.6 Transport of ore and waste

The ore is transported with trucks to the crusher at 800m level. In 2008, the distance

between the ore stopes and the crusher was 2.4 km (from room H1110) and 3.3 km (from

rooms S946 and H1255).

The type of crusher is AR 150 jaw crusher and it has been in operation since 2003. The

crushed ore is transported and dumped by conveyors into the shaft which has a capacity of

2500 tonnes. The shaft is located between 800m and 900m level.

The ore is transported with conveyors to the skip. This process is fully automated. The

second conveyor in the series has a scale which makes sure that a certain tonnage is

loaded onto the skip (capacity of 4. 5 ton per skip and 90 ton per hour). The skip can be

monitored from the surface station. The headframe holds about 600 tonnes. The ore is

loaded onto the trucks with 48 tonnes capacity and carried to the concentrator located in

Boliden (17 km away).

18

Most of the waste rock is used as backfilling material in mined out areas of the mine.

Waste from the upper levels is transported through the Petiknas drift or with the skip. The

waste that is hoisted is not crushed and it is dumped outside of the headframe.

19

2 METHODOLOGY

Before the simulation model of Renström mine was created, a literature study on

simulation was done. The literature study comprised previous technical reports, articles

and books which were written about simulation, Automod and mine transportation

systems.

Secondly, an activity time study in Renström mine was done in order to gather input data

for the simulation model. The activity time study was done only on the highway trucks

and the mine truck. For the time period of the activity study, production planning reports

of Renström mine were used to register the ore stopes and backfilling rooms into the

model.

According to information and drawings from the mine planning section, a new layout of

the mine was prepared in Microstation computer aided design (cad) program.

The new layout with stations, stopes, backfilling rooms, and crusher and meeting points

was sent to ÅF consult to transfer it to AutoMod. After this stage, ÅF started to write the

basic code in order to create the transportation between these points. The main code which

will execute the model was written by Linus Bördin, ÅF, with a continuous and intense

communication between the author and him about the logic behind the transportation

system and the parameters affecting the system. The verification - validation stages were

done by the author by comparing the results with the earlier activity study results and the

necessary corrections in the code was done Linus Bördin, ÅF.

After the model accuracy was judged acceptable, the experimental design stage started and

a large number of runs were simulated. The result of each transportation alternative in

terms of production amount and engine hours were written down in a list and finally after

all the runs finished, the lowest cost transportation model which handled the planned

production was selected.

The results were presented in Renström mine as a recommendation to show the best

transportation system alternative in terms of low transportation cost according to planned

production amount, existing trucks and the mine design.

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3 SIMULATION THEORY

Simulation is the imitation of real life in another controlled environment. For example,

while children play with their toys, they execute a simulation. The other examples can be

Chess and Go which are the simulations of warfare.

According to Cochrane J, “Computer simulation is a tool that is commonly used in

operations research to study the way in which a system works, and to look for ways in

which the system can be improved”.

Simulation study is a quite challenging job and requires both quantitative and qualitative

skills together and a suitable tool. The results coming from a simulation model can be

used to support the decisions regarding a system.

3.1 Simulation in the mining industry

In recent years, mining companies are using simulation models in order to improve,

modify, analyse or/and plan their existing systems. In addition, simulation models that are

working properly can help us to make critical decision by looking into the future and

(more or less) predicting the issues about our system.

Due to the reason that traditional methods such as manual calculations, flow diagrams etc.

is not enough to solve the complex problems, there is a requirement for better methods

and tools for the production planning and the design of the mine.

Many simulation programs have been built and used for different purposes in the mining

industry. There are some examples below:

Simulation of a continuous surface mining system (Aguoutantis and Stratakis,

1998)

Underground Ore handling systems (Bailey, Olsson and Glassock)

Simulation of Pillara’s haulage system (Bradstreet, 2001)

Simulation of Truck/shovel system at Tuncbilek Coal Mine (Cetin, Erarslan and

Okuducu, 2001)

21

Simulation of battery powered coal haulers ( Cochrane, 1998)

Autonomous vs Manual haulage trucks (Parreira and Meech, 2010)

Development of a short term scheduling tool for the Aitik open pit mine using

simulation (Wageningen, 2001)

Simulation studies for truck dispatching (Wilke and Keck, 1982)

Additional examples (from Zhou, 2010):

Studying the performance of surface mining equipment including production

subsystems, waste material , conveyor subsystems and dumping system

Minimizing truck haulage cost which involves determining the optimum fleet haul

size, organization of haul system, the best dispatching scheme and reliable

maintenance and servicing system

Dispatch controlling in surface mines

Planning and analysing the truck/shovel operations in opencast mines and quarries

Studying the truck transportation system consisting of traffic patterns, truck

utilization and operation costs

Selection of dragline and stripping method in surface coal mines

Mine transportation systems analyse of costs

Benchmarking of existing operations

Scheduling maintenance for both production and ground handling system.

Comparison of timing and efficiency between drill – blast method and high speed

continuous mining for new block cave development.

Different logistic options and their logistic consequence on transport from mine

dumps to the proposed new treatment plant

22

3.2 Simulation benefits and disadvantages

According to Banks (2000), the user can through simulation apply different type of rules,

policies, procedures etc. without disturbing the real ongoing real system operation and

different types of design, layout, and transportation systems and understand the

modification availabilities in the system. In addition, the interaction between variables and

their importance on system performance can also be understood within expanded or

compressed time. By showing the information on work and materials, bottlenecks in the

mine can be found or helping new system designs by answering “What if” questions.

In short, simulation helps us to understand how the system operates rather than how

individuals think the system operates (Banks and al. , 1996)

On the other hand, simulation requires experience and special training to be able to build

the model of the existing system. The results taken from a simulation model may be

difficult to understand due to random variable outputs. In addition, analysis and building

the model can be time consuming and expensive (Banks and al., 1996).

However, today, many packages on the market require only input data and give easily

readable output data. Simulation can be performed faster due to computer hardware

advances. Finally, complex systems are very difficult to be analysed by analytical method.

3.3 Simulation Tools

Simulation tools are consisting of three basic classes; general purpose simulation

languages, simulation front ends and simulation packages. The last one, simulation

software package is more advanced than the other ones. There are several simulation

softwares such as AutoMod, Arena, Witness, SimCad, SimMine, Flexsim, SLAM on the

market.

Arena is used from forestry to mining and it is an extendible and popular

simulation/animation package. (www.arenasimulation.com)

23

Witness is a user-friendly simulation system but it is not so common for mining

applications. (www.lanner.com/en/witness.cfm)

SimMine is another simulation package which has been developed solely for mining

activities and for conducting complete mining simulation projects. Due to the reason that

the staff has a good knowledge and wide experience both in programming and mining

activities, it is possible to obtain accurate simulation models with this package.

(www.simmine.com)

AutoMod is an industrial simulation modelling package but it can be adapted to mining

systems. In this thesis work, simulation model of Renström mine has been built by

AutoMod due to previous use of the software within Boliden. (www.automod.se)

3.4 AutoMod

AutoMod has both the features of a general-purpose simulation language and a special

purpose material-handling simulator. With AutoMod, it is possible to simulate some

advanced features such as robots, machine tool transfer system and special machinery.

Movement systems are divided into manually and automated equipment systems.

Material movement systems are as follows:

Path Mover

Conveyors

Automated Storage and Retrieval Systems (ASRS)

Robots

Bridge Cranes

Power and Free Chain conveyors etc

For the material movement systems, paths and stations must be created and then input data

to define the operation is created. The logic which corresponds to the movement system

and the 3D animation which can be observed from any angle is created automatically.

24

Spreadsheets and CAD (computer aided design) packages can easily be imported into

AutoMod (www.automod.se)

On the other hand, AutoMod has some limitations for mine simulations. Firstly, it requires

good command of programming skill and special training is required for model building.

However, model building is learned over time by training and gaining experience of the

programme. Secondly, its implementation over mining transportation systems is very

complicated in terms of programming code.

3.5 The Simulation Process

Computer simulation has several steps which communicate with each other all the time.

Due to this reason, it is a continuous and dynamic process.

The simulation model of Renström mine is discrete event simulation. The transportation

system has a sequence of events and all these events are in order. These events occur at a

specific time in discrete event simulation (Robinsson, 2004).

Discrete event simulation is used to model and evaluate real systems over time. A system

can be static or dynamic. The model used for discrete event simulation is dynamic because

the system changes by time (Banks et al.,2000).

“Discrete event simulation utilizes a mathematical/logical model of a physical system that

portrays state changes at precise points in simulated time. Both the nature of the state

change and the time at which the change occurs mandate precise description. Customers

waiting for service, the management of parts inventory or military combat are typical

domains of discrete event simulation” (Nance 1993, cited from www.albrechts.com)

The first step in the simulation process begins with identifying the goals for the simulation

and understanding the system which will be modelled (see Figure 4 and 5). Secondly, the

problem is formulated in terms of mathematic. Then, the formulated problem is

transferred into the simulation software. After the model is transferred and created, the

next step is the verification step. In this step, the model is verified by controlling that

reasonable output is given from inputs which are collected from real operation. The

http://www.automod.se/

25

question “Is the model/program performing properly?” must be asked. In the fifth step, the

validation step, the conceptual model is checked to understand and to decide if it

represents the real system or not. In the following step, the experimental design step, the

simulated alternatives, critical performance measures, number of runs, simulation length is

determined. The seventh step is the analysis of the results. In order to evaluate the

outcomes of the results one must get insight of the results by analysing the results. In the

final step, documentation of the work is done and includes findings and recommendations

in it.

26

Figure 4: The life cycle of a simulation study (Balci, O., 1990)

27

Figure 5: Steps in a Simulation study (Groumpos, P. & Merkuryev, Y.)

28

4 DEVELOPMENT OF the SIMULATION

MODEL

The computer model of Renström mine was built by using the software package

AutoMod. It is possible to see the interaction between the loading machine and

transportation vehicles in the model. The logic behind the model is written into AutoMod

by using programming language and an excel interface is created and combined with the

model in order to run different scenarios of the haulage process. In the excel interface,

there are different categories of input data and output data.

4.1 Excel Interface

The excel interface consists of two sections; Input data and Output data section. Prior to

simulation runs, the output data section is completely empty. The output data section

presents only for gathering the results of each run. The input data section is filled with

required data in order to be able to extract results from the model.

The sheets in the input data section are:

General input

Blasting plan

Backfilling

Cycles

Machines

Shifts

For details see Appendix II.

29

The sheets in output data section are:

General output

Log

Vehicles

Haulers

Cycle log

Vehicles table

For details see Appendix III.

4.2 Verification

In verification stage, the model is tested and evaluated as to whether the model is an

accurate representation of the formulated problem or not. It is very important to verify that

the program is performing properly and the conceptual model is an accurate representation

of the real system (Koivisto, 2001). The reasons for the model not being accurate can be

concerning the logic or the code behind the model. The necessary corrections are made

after the analysis of the results.

In Automod, the corrections in the programming code and logic must be done

continuously until the model is judged as reasonable. Therefore, the communication

between the user (and someone who knows the real system very well) and the programmer

is very important to be able to build a good model that is working properly.

During the verification of the model, it is important to judge if the results are reasonable

and reflecting the reality or not. As it is mentioned before, mistakes can be due to

programming code and logic. In order to understand if it is due to the programming code a

log file where all the activities are being logged after every activity for each machine is

useful. By going through the log file, analysing the activities in the list, the simulation

model of Renström has been verified.

30

4.3 Validation

The validation step was done according to the activity study which was conducted in

September to October (2010). This activity study was done in order to gather input data

for simulation and to calculate and determine the transportation cost of existing

transportation system in Renström. Due to the model already being built according to the

existing plan of September to October period; the results of this period from activity study

and the model have been compared.

Firstly, the existing transportation scenario, one mine truck and three highway trucks, has

been entered to the model input section and the output generated by the model has been

compared with the real production data. All parameters such as production amount, MTBF

(mean time between failure), MTTR (mean time to repair); engine hours, costs etc. are

more or less matching with the results from the activity study. Small difference in values

is due to availability of machines and utilization of shift and the other assumed values for

the calculation of costs. Some values have to be assumed due to no available data on

maintenance services and costs in Renström.

4.4 Sensitivity of the simulation model

The calculation of the ore transportation cost for mine truck and highway truck is

consisting of many parameters. The effect of making error with the estimation of these

parameters is varying. Due to this reason a sensitivity analysis has been conducted on the

input and output parameters of the model.

The sensitivity analyses are done on the following parameters:

Production per period (tonne)

Required engine hours

Availability

Shift utilization

Number of drivers per shift

31

Total man hours per period

Driver salaries (SEK/hour)

Maintenance cost (SEK/motor hour)

Diesel cost (SEK/m3)

Tire cost (SEK/tonne)

Life length of trucks (engine hours)

Purchase price

Depreciation per period

In the table below, the results from the sensitivity analysis; the influence of each

parameter on the cost is shown.

RANK Highway truck & Mine truck

HIGH

Influence

LOW influence

1

Production (tonne/period*)

2 Required engine hours

3 Availability, shift utilization and available

working hours

4 Number of driver per shift, salary and required

man hours

5 Life length of trucks (motor hour)

6 Purchase price and depreciation per period

7 Maintenance cost (SEK/motor hour)

8 Diesel cost (SEK/m3)

9 Tire cost (SEK/tonne)

Table 4: Parameters and their influence on cost calculation for Highway and Mine trucks

*period = 8 weeks

32

Figure 6: Sensitivity analysis for Highway truck (20% over and under estimations)

In figure 6 and 7, the most sensitive parameters in the cost calculation are required engine

hours and production amount. Moreover, the tire and diesel cost are the least sensitive

parameters in the cost calculation. In other words, any mistake in the calculation of tire

and diesel cost will not lead big deviations in the result.

The sensitivity analysis shows the same results for both highway truck and mine truck (see

Figure 6 and 7). The transportation cost is very sensitive to required engine hours and the

planned production amount. Any small mistake that will be done in the calculation of

these parameters leads to large changes in cost calculation. Therefore, this is another

reason why Renström mine is simulated in order to estimate the cost instead of the cost

being calculated manually.

If the required engine hours are overestimated or underestimated by 20% the difference is

13.29 SEK/tonne. According to Renström production plans, the amount of production for

33

8 weeks is 76 500 tonne. The difference in transportation cost becomes 1 016 685 SEK for

8 weeks and 6 100 110 SEK per year.

However, if the sensitivity of the tire cost is observed, then the difference is only 0.91

SEK. This becomes 69 615 SEK for 8 weeks and 417 690 SEK per year. Thus, it is not as

sensitive as required engine hours.

Figure 7: Sensitivity analysis for Mine truck (20% over and under estimations)

To sum up, production amount and engine hours are the most sensitive two parameters in

transportation cost calculation. In other words, any mistake that will be done in the

calculation of these parameters will cause large diversions in transportation cost as

mentioned above.

34

5 SIMULATION RUNS AND RESULTS

52 different transportation alternatives have been simulated in order to find the cheapest

option for ore and waste transportation in Renström. Some transportation alternatives

include both mine trucks and highway trucks (Table 7 and 8) and some alternatives

contain only highway trucks (Table 5) or mine trucks (Table 6). The number of trucks has

been changed between runs in order to find the effect of truck type and quantity on

transportation cost for the ore to the crusher by including maintenance, tyre, fuel, driver

etc. costs. In addition, the number of loaders has also been changed to see how the

production is being effected by the loaders (Table 5, 6, 7 and 8).

16 runs with only highway trucks and 12 runs with only mine trucks have been simulated.

For mine truck-highway truck combinations, two groups have been created; one with a

reserve truck (12 runs) and one without a reserve truck (12 runs). When the target

production amount 76 500 tonnes is reached, there is no longer need for more runs. For

some options, production amount is more than 76 500 tonnes. The reason behind this is

the last blasts which are blasted at the end of the period are still being transported on some

additional days. Thus, the maximum production amount of the mine in 9* weeks is 79 566

tonnes. However, the transportation in 8 weeks is 76 500 tonnes.

For the simulation runs, all the parameters have been fixed stable according to the real

system in Renström mine in terms of capacity of trucks and cycle times. The only changed

parameters are the number of trucks and loaders in the model.

*(8 weeks + some additional days = 9 weeks)

35

Runs Total production

(tonne) Number of loader Number of highway trucks

1 21163 1 1

2 22998 2 1

3 27668 1 1+reserve

4 32579 2 1+reserve

5 32666 1 2

6 42603 2 2

7 33496 1 2+reserve

8 64243 2 2+reserve

9 33845 1 3

10 63276 2 3

11 33845 1 3+reserve

12 76245 2 3+reserve

13 33695 1 4

14 75115 2 4

15 33695 1 4+reserve

16 77114 2 4+reserve

Table 5: Simulation runs with only highway trucks

*Reserve truck is used in case of failure and service time of a production truck. It is also a highway truck

According to Table 5, the alternatives with only 1 loader cannot cope with a planned

production amount of 76 500 tonne. There is only one alternative that can handle more

than the planned production; run 16, 4 highway trucks with one reserve truck.

According to Table 6, there is no alternative that can handle the planned production with 1

loader. Thus, if only 2 loader alternatives are focused on, then there is again only one

alternative that can handle the production; run 28, 3 mine trucks with reserve truck. The

reserve truck is also a 36 tonne mine truck.

36


(tonne) Number of loader Number of mine trucks

17 28136 1 1

18 33525 2 1

19 29258 1 1+reserve

20 36208 2 1+reserve

21 33198 1 2

22 66831 2 2

23 33695 1 2+reserve

24 70042 2 2+reserve

25 33270 1 3

26 75292 2 3

27 33270 1 3+reserve

28 76663 2 3+reserve

Table 6: Simulation runs with only mine trucks

Beside these two types of runs, only highway truck and only mine truck, the combination

type alternatives are simulated. The combination types are the combined usage of mine

trucks and highway trucks in the mine. However, this combination alternatives are also

divided into two subgroups; trucks with and without a reserve truck.

37


(tonne)

Number of loader Number of highway trucks

Number of mine trucks

29 33695 1 1 1

30 52782 2 1 1

31 33695 1 1 2

32 74228 2 1 2

33 33844 1 2 1

34 72226 2 2 1

35 33696 1 2 2

36 76664 2 2 2

37 33643 1 3 1

38 76936 2 3 1

39 33398 1 1 3

40 77113 2 1 3

Table 7: Simulation of combination (both mine trucks and highway trucks) without reserve truck

According to Table 7, simulation runs with 1 loader cannot meet the production target but

run 36, 38 and 40 have higher productions than 76 500 tonne. The first feasible

combination is 2 highway trucks with 2 mine trucks, the second alternative is 3 highway

trucks with 1 mine truck and the last alternative is 1 highway truck with 3 mine trucks.

38


(tonne)

Number of loader Number of highway trucks

Number of mine trucks

41 33696 1 1+reserve 1+reserve












Table 8: Simulation runs of combination with reserve truck

In Table 8, runs with 1 loader does not meet the production target but Run 44, 46, 48, 50 and 52

have higher production than 76 500 tonnes.

In Table 9 below, the alternatives that can meet the planned production target are shown in

summary.

Options Ratio Total

production** Number of loader

Number of highway trucks

Engine hours Number of mine

trucks Engine hours

16 1.34 77114 2 4+reserve 1565 - -

28 1.00 76663 2 - - 3+reserve 1469

36 1.21 76664 2 2 633 2 895

38 1.32 76936 2 3 1060 1 481

40 1.10 77113 2 1 227 3 1285

44 1.10 76664 2 1+reserve 469 2+reserve 1029

48 1.17 77113 2 2+reserve 766 2+reserve 791

50 1.10 77113 2 1+reserve 362 3+reserve 1173

52 1.25 78281 2 3+reserve 1168 1+reserve 409

Table 9: Simulation runs with productions higher than 76 500 tonne and transportation cost ratios for each option

*Ratio is the price difference between the alternatives according to the cheapest option. For instance, option 1 is 34% more expensive than option 2 (the cheapest option)

**Production = Total transported amount of waste + ore production

The production target of waste and ore in total is about 76 500 tonnes according to

production plans of Renström mine. The corresponding engine hour for this amount of

production is approximately 1500 truck engine hours.

According to Table 9,

All the options can transport more than 76 500 tonnes in 8 weeks.

If only highway trucks are in operation without a reserve truck, then the

availability is 77%. However, if the highway trucks work together with a reserve

highway truck then the availability increases from 77% to 95 %. Similarly, the

availability of mine truck also increases from 95% to 99 % with the existence of 1

reserve mine truck. The reason why the availability cannot reach up to 100% is due

to small failures during operation time.

The options simulated in run 36 2+2 (2 highway trucks + 2 mine trucks), Run 38

3+1 (3 highways+1 mine truck) and Run 40, 1+3 (1 highway+3 mine truck) are not

recommended because they do not have any reserve truck and in case of failure of

a truck, these options cannot meet the production requirement of 76 500 tonnes. In

case of failure, for example, Run 38 becomes like Run 34, 2 highway trucks + 1

mine truck with a production of 72 226 tonnes or like Run 10 only 3 highway

trucks with a production of 63 276. Thus, these three risky options (Table 10) must

be discarded from the best option table (Table 9).

41

Risky options Run 36

(2 + 2 )

Run 38 Run 40

If 1 truck breaks

down

Run 36 becomes like

Run 34 with 2+1 or

Run 32 with 1+2.

None of them can

reach the target

production.

Run 38 becomes like

Run 10 with 3

highway trucks or

Run 34 with 2+1.

None of them can

reach the target

production

Run 40 becomes like

Run 26 with 3 mine

trucks or Run 32

with 1+2. None of

them can reach the

target production

Table 10: Risky options

If the production amounts are grouped within the Table 6, 3 production groups;

77 113-77 114 tonnes, 76 663-76 664 tonnes and 78 281 tonnes are created. The

reason why costs are being compared according to production amount instead of

number of trucks is as mentioned before. Transportation costs are calculated

according to corresponding motor hours to each production amount.

According to Table 11, the most expensive option is Run 16. Four highway trucks

are being used in the mine with reserve truck. The next most expensive options are

Run 52 and Run 48.

In table 11, the cheapest options of each group are Run 28, Run 50 and Run 52.

Due to the reason that Run 52 cannot be compared with any other option in its own

group one more extra simulation has been done. After comparison, the extra run is

selected instead of Run 52 as the cheapest option of the third group. The reason

why 4 mine trucks are selected is that only 4 mine trucks with one reserve truck

can reach the production amount of 78 280 tonnes.

42

Production (tonnes) Cost

(SEK/tonne)

Options

Runs

Highway truck Mine truck

76 663-76 664 tonnes

26.44 - 3+reserve Run 28

29.00 1+reserve 2+reserve Run 44

77 113-77 114 tonnes



35.50 4+reserve - Run 16

78 280-78 281 tonnes


27.14 - 4+reserve Extra

Table 11: Transportation options that meet the production target of 76 500 tonnes

According to the results,

o For 76 663 tonnes production, 3 mine trucks with a reserve truck with a cost

of 26.44 SEK/tonne is the cheapest option.

o For 78 280 tonnes production, 4 mine trucks with reserve truck with a cost of

27.14 SEK/tonne is the most effective and productive option. However, the

required amount of production is only 76 500 tonnes for 8 weeks. This

option is producing 1 780 tonnes more so it can be used in the future if the

production amount will be increased.

An example on calculation of transportation cost is shown in the table below but some

values are confidential such as purchase prices, salaries etc.

43

Highway truck Mine truck

Period (weeks) 8 8

Weeks in a year 48 48

Production (tonnes) 77114 76663

Average gradient 1:8 1:8

Average Lift height 371 m 371 m

Cycle time 28 min 40 min

Tonnage of truck 25 tonnes 36 tonnes

Required engine hours acc. tonnes 1565 1469

Amount of shifts 3 3

Working hours exc. holidays 360 360

Total shift hours 1080 1080

Availability (Ratio) 1 1.23*

Shift utilization

Required amount of trucks 4 3

Amount of driver per shift 3.1 3

Extra truck 1 1

Total man hours

Maintenance cost (SEK / motor hour)

Diesel price (SEK / m3)

Diesel consumption (lt / hr) 24 35

Tire cost (SEK/tonnes)

Total sum salary (SEK/period)

Life length motor hour

Depreciation year

Purchase price

Depreciation per period

Total cost per ton (Ratio) 1.34** 1

Table 12: Calculation table for the cost of transported ore

*The availability of the mine truck is 23% more than the availability of the highway truck.

**The transportation of same amount of material is 34% more expensive with highway trucks than with

mine trucks.

44

6 DISCUSSION AND CONCLUSION

The scope of the simulation project is to compare the effect of usage and number of

highway trucks and mine trucks on the costs for transport of ore and waste rock in

Renström mine. The main consideration in the mine is to decide how many and what type

of truck that is the best option to be used for the transportation of ore and waste rock with

respect to operation cost per tonne.

AutoMod simulation software has been very helpful for the determination of engine hours,

total production amount, shift utilization, availability of trucks and has also showed how

the selection of trucks affects the costs and the production. If the calculations had been

done manually instead of using simulation with AutoMod, it would have taken very long

time and the results would not have been a good reflection of reality due to Renström

mine being a complex system containing many factors that cannot be handled manually

that is affecting the transportation. However, the model has been build neither as

complicated as reality nor too simple and it is possible to test different transportation

strategies by using it.

On the other hand, due to the reason that AutoMod is designed for industries such as

manufacturing, automotive, airport baggage handling etc., both the graphics and the logic

of the program is not so suitable for the mining industry. For the users who are not

familiar with programming, AutoMod can initially be difficult to use. Moreover, while the

excel interface is giving opportunities to make changes in input data, it can also cause

some mistakes due to the reason that some input parameters must not be changed such as

speed, tonnage of the truck and the activity durations.

As an advice, when using the AutoMod program, the programmer and the person who

knows the mine very well should build the model together, especially in the model

building and verification stages.

A mine truck can be 2-3 times more expensive than a highway truck. Instead of using only

mine trucks in the mine if highway trucks are bought due to their lower purchase prices

then the transportation cost per tonnes increases approximately 34%.

45

In addition, in the combination alternatives, if the mine truck does most of the job and

carries more than the highway truck the transportation cost per tonne is sinking

approximately with 10 to 20%.

The availability of the mine trucks is 23% more than the availability of the highway

trucks.

It is very important that the reserve truck is able to transport the required amount of

production material in a given period. In case of failure and service time for a production

truck, one reserve truck must always be ready to replace the production truck and continue

to transport material to the crusher and the backfilling rooms.

The results taken from this study are an input to the discussions about ore & waste

transportation trucks in Renström mine. Due to the reason that highway trucks are

designed for normal highway conditions, they are faster and easier to manoeuvre. On the

other hand, mine trucks are designed according to mine environment. They are tough and

relatively slow moving machines in comparison to highway trucks. It is sometimes hard to

convince the mine workers about the effectiveness of these two different kinds of trucks.

Most of the workers believe that highway trucks are the most effective due to their cycle

time. However, these trucks are not designed according to tough mine environment and

their mean time between failure (MTBF) is very short and the vehicles are wearing out

very quickly in comparison to the other highway trucks that are driven on normal city

roads and to the mine trucks. Therefore, the availability of the highway are lower than the

availability of the mine trucks.

In conclusion, the cheapest alternative for Renström mine in order to reach the required

production target and to obtain a relatively cheap transportation cost is to use 3 mine

trucks with a capacity of 36 tonnes (corresponding to 16 m3) and 1 reserve truck.

46

7 FUTURE WORK

While working with simulation model of Renström mine, the requirement for

development and some changes in the model has been discovered. This need for

development of the model is due to the project participants not having enough experience

with the software, AutoMod, and that the model has not been built together with a

programmer. Most information about the mine was transferred over the telephone and by

mail. The second reason is that the requirements are being discovered while using the

programme. For instance, the output section especially must be changed and reorganized

in order to collate the results easier.

In the current model, cycle times, service and failure hours have been described using the

uniform distribution. The triangle distribution has been used for meeting duration. For

further work, documentation of the cycle times of all the machines in the mine should be

done in order to find the appropriate statistical distribution for each of them. Thus, the

model becomes more realistic because cycle times can vary depending on the situation and

the wear of the machines. While the cycle times of the machines are being followed up,

the need for maintenance can also be discovered. Namely, if the cycle times are

continuously increasing, it means that the machine is wearing out and needs maintenance.

Therefore, this can also decrease the costs due to the possibility to decrease the number of

unplanned stops.

For further work, other types of simulation tools should also be investigated to find the

most suitable tool. However, before investigation, the further requirements and

expectations must be addressed in terms of production planning.

For the continuation with AutoMod software, the expected results must be properly

addressed and the communication between the programmer and the user should be

strengthened in the model building and verification stages.

47

REFERENCES

Albrecht, M.C. (2010). Introduction to Discrete Event Simulation.

http://www.albrechts.com/mike/DES/Introduction%20to%20DES.pdf [accessed

30/05/2011]

AutoMod Simulation.Software . Simulation of production and logistic.

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Aguoutantis Z.G. & Stratakis A., (1998). Simulation of a Continuous Surface Mining

Systems Using the Micro Staint Visual Simulation Package. In Information technology in

the mineral industry. Panagiotou, G.N. & Michalakopoulos T.N. (eds.). Rotterdam:

Balkerna, p.85.

Arena Simulation.Software. http://www.arenasimulation.com [accessed 22/02/2011]

Bailey, M., Olsson, B. & Glassock, C. Underground Ore Handling Systems. Australia. [no

date]

Balci, O., (1990). Guidelines for successful simulation studies. Proceedings of the 1990

Winter Simulation Conference, pp.25-32

Banks, J., (2000). Introduction to simulation. Proceedings of the 2000 Winter Simulation

Conference, pp. 9-16.

http://www.albrechts.com/mike/DES/Introduction%20to%20DES.pdf

48

Bradstreet, D., (2001). Simulation of Pillara’s haulage system.

Boliden Mineral AB (1999). Technical reports about Simulation.

Boliden Mineral AB. http://www.boliden.com [accessed 07/01/2011]

Cetin, N., Erarslan I.C. & Okuducu, A. (2001). Computer simulation of Ttruck/Shovel

System at Tuncbilek Coal Mine using GPSS/H. 17th

International Mining Congress and

Exhibition of Turkey.

Cochrane, J., (1998). A computer simulation of Battery powered coal haulers.

Groumpos, P. & Merkuryev, Y. A methodology of Discrete-event simulation of

manufacturing systems: An overview. Greece: University of Patras. [no date]

Koivisto, S. (2001). Production scheduling in Cut&Fill Underground mines using

simulation. Finland: Helsinki university of Technology.

Parreira, J. & Meech, J. (2010). Autonomous vs Manual haulage trucks – How mine

simulation contributes to future haulage system developments. Canada: CIM meeting

Robinson, S. (2004). The practice of model development and use. Wiley

SimMine Simulation Software. http://www.simmine.com [accessed 24/03/2011]

Wageningen, M.A, (2001). Development of a short term scheduling tool for the Aitik open

pit mine using simulation. Delft University of technology.

49

Wilke, F.L. & Keck, K., (1982). Simulation studies of truck dispatching. In 17th

APCOM

Processings. Col. School of Mines, Golden, CO and pub. By SME, Littleton, CO, pp. 620-

626

Witness Simulation Software. http://www.lanner.com/en/witness.cfm [accessed

23/03/2011]

Zhou, J., (2010). Analysis of a Mine-Mill Production System Using Simulation and Integer

programming. Nova Scotia: Dalhousie university.

50

APPENDIX I

Details on the Simulation Model

51

In this work, a haulage transportation model program for an underground mine according

to today’s existing model has been built. With the help of animation of this system,

different activities such as waste rock/ ore transportation and backfilling can be observed.

The purpose of the model is to simulate the underground haulage system of Renström

mine to decide which transportation method is the most effective one to achieve high

production capacity and low cost.

Figure 8: Different activities during working hours (source: Caterpillar)

1. Scheduled hours and Out of plan

The total hours (whole time) are divided into Scheduled and Out of plan hours (Figure 8).

While the scheduled hours of the machines are defining the shift hours, Out of plan hours

are the moments that no work is scheduled in the mine.

Scheduled hours are the sum of Available hours and Maintenance hours. Available hours

are also divided into two as Operation and Idle time. Operation time consists of Working

52

and Delay time. There are two types of maintenance such as planned and unplanned

maintenance.

Working hours begin after preparation time (Idle) and continues until lunch break (Idle)

and after lunch break is completed, everyone starts to work again until leaving time (Idle).

In this simulation model, we will mostly focus on transportation and loading system.

Every shift begins with preparation hours when every worker is informed about the place

and the machine they will work with, goes down into the mine by skip and make prestart

check to the vehicle that they will drive today, fuel it and then travel to the place where

they will work. The second reason for preparation time is to wait in case of rock fall due to

the seismic shakings created by blasting.

Between preparation and lunch break and between lunch break and leaving, there are

working hours (run). During lunch breaks, the machines only stand still in their working

places and when the time is completed then they continue to work again until the next

break/moment.

The leaving time is the time for workers to evacuate the mine until no one will be left due

to blasting activity. After blasting, ventilation is done and the new shift starts.

2. Working hours

The first activity in the mine begins with drilling and continues with the other activities

which are shown in Chapter 1. All the machines are sent to their assigned working places

from their defined starting points in AutoMod (Table 13).

Machine Activity Starting point

Drillrig Drill V1180_Drillstart

Charger Charge 1165_Dynamitupplag

Loader Load V1180_Loadstart

Highway truck Haul 850_Truckstart

53

Mine truck Haul 880_Minetruckstart

Scaler Scale V1180_Scalestart

Shotcrete Shotcrete 1000_Shotcretestart

Resin_Bolt_rig Bolt V1180_Boltstart

Cement_Bolt_rig Bolt V1180_Boltstart

Cement_mixer Cement Petiknas_Surface

Watertruck Water V1180_Waterstart

Table 13: The corresponding start points of the machines

All the machines that have completed their cycle either checks if any other job is available

or disappear from the model and the next cycle together with its corresponding machine

starts. Only 2 trucks are ordered by the loading machine, loading is done and then the

loaded trucks are sent to the dumping destination according to the type of transportation

material. If the material is ore, the only destination is the crusher at 800 level. Moreover, if

the load is waste rock then the destination varies but the program assigns it according to

backfilling information which is in Input file (see App. II). The trucks find the destination;

dump the material and travels back to the loader again. If there is more than one loader

then the truck is always ordered by the same loader. During loading and travel, there are

many parameters such as speed in different conditions (loaded, empty, up, down flat) and

tonnage that the vehicle must communicate with the input data. The number of loads is

calculated according to the truck capacity and the total tonnage of blast that will be hauled.

3. Delay Time

Delay time consists only of queue time and meetings on the ramp. Manoeuvring time can

also be added into this section but in the model, manoeuvring time is included in loading,

meeting and dumping time due to the reason that it would be too complicated to separate it

in the model.

54

4. Idle Time

Idle time consists of lunch breaks, preparation (fuelling, prestart check, distribution of

work type and place for each machine), leaving, blasting and ventilation.

5. Scheduled and unscheduled maintenance time

For unscheduled maintenance times (for failures), the input values of Mean Time between

Failure (MTBF) and Mean Time to Repair (MTTR) for all the machines in the mine are

found in the excel file. For maintenance duration, uniform distribution is used. As an

example, a drill rig can be out of order in the range of every 16 to 24 hours. It is shown in

the excel file as MTBF: 20±4. MTTR is also written in a same way.

In the program, vehicles control the watch to see if they have reached their MTBF limits

to be out of order. After this, vehicles disappear from the scene and they start to count for

the MTTR.

For scheduled maintenance times (for service time), there is service frequency and service

time columns in the excel file. The vehicles check if they have reached service frequency

hours and if they reach that limit they go to the workshop and disappear from the model

until they will fill service hours which is defined under Service Time column in excel file.

The machine becomes available again until the next MTBF or Service frequency.

6. Number of vehicles and capacities

There are extra number of machines in the program and their availability in the program is

controlled from the column “Manned yes/no” in excel file. In other words, if 4 trucks

would like be used, then it is written “yes” and for the ones which are not being used, it is

written “no”. All the vehicles have their own figures in the model and can be seen during

simulation run.

Only the capacities for highway trucks, mine trucks and loaders have been defined in

excel file. For the rest of the vehicles, Factor 1 which has no effect is written as a capacity.

55

7. Driving speed for mine/highway trucks

The driving speeds of the trucks are assigned according the results taken from time studies

in Renström. Mine truck and highway truck has different speeds according to the load

situation. 6 different speeds are defined for every machine in the mine. The driving speeds

of the other vehicles are not only reliable and important but also have no effect on trucks.

These six different speeds are:

Loaded

o Flat surface

o Ramp up

o Ramp down

Unloaded/Empty

o Flat surface

o Ramp up

o Ramp down

The average activity time for transport down and up is calculated by AutoMod due to

changing speed and driving distance.

8. Loading, Dumping, Meeting and Manoeuvre times

Highway trucks and mine trucks have their own cycle times for loading, dumping,

meeting and manoeuvring.

During loading activities, the number of buckets is not shown in the model. Instead, the

total load that the truck can receive (25 ton or 36 ton) is loaded at once onto the truck by

using defined loading time in the excel interface. Loading duration also includes

manoeuvring time of the truck. In other words, in reality, the truck reverse to the loading

point and loading starts and when it is completed, it leaves the loading point and travels to

the destination point (Figure 9). Due to the fact that it is unnecessary to show every little

56

detail in the program, the trucks drive into the loading point straight and they leave there

by turning 180°. This turning does not take any time in the model but in reality, there is

manoeuvring time. In order not to lose this time in the model, the loading time includes

the manoeuvring time in itself as well.

Dumping and meeting durations are done in a same way as loading. All these durations

are different for mine truck and the highway truck, see Appendix III.

The meeting on the ramp is arranged only according to highway/mine trucks because, in

reality, they have priority to drive first and all the other vehicles must give way to them. If

two trucks meet on the ramp then the program controls which one of them is driving

upwards. The truck travelling upwards has always priority to drive first. However, if the

truck is the one that must give way to the other truck then it must stop and wait there and

count the meeting duration together with manoeuvring duration. For meeting times,

triangular distribution is used and for the rest, uniform distribution.

Figure 9: The view over loading activity

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9. Blasts and Dumping places (crusher or backfilling room)

The blasts are listed according to which date they will be blasted and the blast type. There

is dependency between blasts so that before the first planned one is blasted, the second

one cannot be blasted and transported. The total tonnage of the blast is divided into the

capacity of the trucks (25 ton or 36 ton) to plan how many times they will drive there and

pick up the load. When the loading and the transportation finishes, the next blast is blasted

and hauled in the same way.

The dumping places are divided into two as crusher and backfilling room. All the

transported ore goes to the crusher and waste material goes to the backfilling room.

The rule about backfilling is that the program first controls if there is any room is being

filled right now, if so then that room is selected until it is completely filled, if not then it

tries to find the next nearest available date of filling. If there are 2 rooms available from

the same date for backfilling, then the nearest room to the loading point is selected first

and until that room is filled, the other room is not allowed to be filled. In case of no room

is available but vehicles have to dump it to somewhere, no dummy room is created.

Instead of that, the capacity of each backfilling room is increased.

10. Process Flow for each machine in the mine

There are 10 different processes in the mine and the logic behind each process is shown in

each flow chart. The process flow has been tried to be kept as simple as possible to

understand the relation between different processes during production time. Drilling,

charging, watering, scaling, cleaning and bolting activity flows are exactly the same in the

program logic. Loading activity works together with hauling activity and shotcreting

activity works with concrete mixer truck.

As mentioned before, every loading machine orders only 2 trucks which can be whether

highway truck or mine truck according to which machines are released from Input data

file.

The shotcrete machine must always work together with the concrete mixer truck due to

small box volume of the shotcrete machine. While the shotcrete machine is spraying

concrete, the concrete mixing truck is parked behind it and cement is loaded into the

58

cement box of shotcrete machine. The mixing truck brings the cement through Petiknäs

ramp from Surface level and there is not so much need for the mixing truck to go and

bring cement again.

59

APPENDIX II

Input data for simulation model

60

The required input data for the simulation modelling has been gathered from Renström

mine employees, technical reports, experiences and time studies conducted in Renström

mine.

An activity in the mine starts with drilling and continues until bolting and then starts from

the beginning again. Sometimes backfilling and cut change follows the bolting and then

new operation starts from drilling. The table 14 shows the different activities together with

corresponding machines in today’s Renström mine. (Note: the list of the activities is not

in order)

Activities Machines Amount

Drilling Tunnel rounds are drilled by Atlas Copco E2C jumbo and L2C 1+2

Charging Atlas Copco charging trucks 2

Blasting and

Ventilation

No need for machine -

Watering Watering of muckpile after blasting and before loading is done by

water truck Volvo BM A25 or manually using a hose

1

Loading Toro 0010, Sandvik LH514 and Volvo BML180E loading machine 2+1+1

Scaling Jama SBU 8000 and 800 scaling machine 1+2

Primary cleaning Usually done by Toro and not sufficient for drilling of tunnel rounds 2

Bolting* Bolts are installed by Atlas Copco Boltec either resin anchored or

cement grouted bolts.

2+1

Shotcreting Jama concrete spraying machine and Volvo A25 concrete mixer truck 1+2

Settle time for

shotcreting

n/a -

Backfilling** Is done by highway trucks or sand filling with hoses and Toro loading

machine

-

Haulage of ore Is done by highway trucks and mine truck 4+1

Fine cleaning Usually done by a wheel loader prior to drilling of round tunnels 1

Table 14: The list of activities in the mine

* There is no difference in usage of Atlas Copco Boltec resin anchored and cement grouted. They are being selected

only according to their availability.

61

** For backfilling, either Toro loading machine is selected or Volvo FH 480 highway trucks are sent according to their

availability.

Monday -Thursday Friday Saturday Sunday

Early shift 06:00 – 14:15 06:00 – 14:15 06:00 – 14:15 06:00 – 14:15

Late shift 15:00 – 23:15 15:00 – 22:00 20:30 – 05:00

(if the week number is

even)

Night shift 00:00 – 05:00

Table 15: Working hours in the mine for early, late and night shift

In table 15 and 16, working hours and the blasting hours in Renström mine are shown.

Monday Tuesday - Thursday Friday Saturday - Sunday

Early shift 05:00 – 06:00

(if the late shift

works on Sunday)

05:00 – 06:00

05:00 – 06:00

Late shift 14:15 – 15:00 14:15 – 15:00 14:15 – 15:00 14:15 – 15:00

Night shift 23:15 – 00:00 23:15 – 00:00 22:00 – 22:45

Table 16: Blasting and Ventilation hours for each shift team

There are 2 types of cycles in Renström. They are shown in the table below (Table 17)

according to the activity order with activity durations. No duration time has been assigned

for loading due to varying loading hours according to each blast tonnage. It will be

calculated in AutoMod and indicated in output file.

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Cycle type 1 Cycle type 2 Duration (average) Duration +/ -

Drilling Drilling 2.5 hr 1

Charging Charging 1.5 hr 0.5 hr

Blasting Blasting See table 11 -

Ventilation Ventilation See table 11 -

Watering Watering 0.25 hr 0.1 hr

Loading Loading - -

Scaling Scaling 1.83 hr 0.5 hr

Primary cleaning Primary cleaning 0.66 hr 0.16 hr

Shotcreting Shotcreting 0.83 hr 0.17 hr

Settle time for shotcreting Settle time for shotcreting 4 hr 1 hr

Bolting Bolting 3 hr 2 hr

Fine cleaning 0.5 hr 0.25 hr

Table 17: Different cycle types and their durations (Cycles sheet in excel)

Speed Speed Speed Speed Speed Speed

Capacity Manned flat flat up up down down MTBF MTBF MTTR MTTR Service Service Starting point

Machine ID Activity_ID ton/factor yes/no Loaded

(km/h)

Empty

(km/h)

Loaded

(km/h)

Empty

(km/h)

Loaded

(km/h)

Empty

(km/h)

Average

(hrs)

+/-

(hrs)

Average

(hrs)

+/-

(hrs)

Freq.

(hrs)

Time

(hrs)

Place name

Drillrig_1 Drill 1 yes 5 5 2 2 2 2 20 4 3 2 200 8 V1180_Drillstart

Charger_1 Charge 1 yes 10 10 10 10 10 10 20 4 3 2 150 8 1165_Dynamitupplag

Loader_1 Load

Cleanprimary

backfill

11 yes 5 5 5 5 5 5 70 20 3 2 200 8 V1180_Loadstart

Highwaytruck_1 Haul 25 yes 20 25 16 17 14 21 10 2 3 2 200 8 850_Truckstart

Minetruck_1 Haul 36 yes 15 20 10 16 14 16 500 100 6 4 250 8 880_Minetruckstart

Scaler_1 Scale 1 yes 15 15 5 5 6 6 10 2 3 2 200 8 V1180_Scalestart

Shotcrete_1 Shotcrete 1 yes 10 10 10 10 10 10 20 4 3 2 150 8 1000_Shotcretestart

Table 18: The example view over machine properties table in excel for AutoMod (Machines sheet in excel)

In Table 18, different properties of machines such as speed, MTBF, MTTR, service frequency and service duration are shown. All the

information in this table is gathered by activity time study in Renström. However, MTTR and MTBF hours could not be gathered by time

study. They have been determined by trial and error method with comparison to cycle times.

64

Machines Amount of machines in Renström Mine Max amount of machines in simulation model

Production drillrig 3 6

Charging truck 2 3

Water truck 1 1

Loader 4 5

Highway truck 4 6

Mine truck 1 6

Scaler 3 3

Cement mixer 2 2

Shotcrete machine 1 2

Bolting machine

(plast & cement)

3

(2+1)

3

Table 19: Amount of machines in reality and in AutoMod

In order to try different alternatives in AutoMod with different number of machines and see how the number of machines is affecting the

production amount, extra machines have been created in the simulation model (Table 19).

Scheme Monday - Thursday Friday Saturday Sunday

1 day Start Week Start Week Start Week Start Week

run 00:00 Odd 00:00 Every

lunch break 02:00 Odd 02:00 Every

run 03:00 Odd 03:00 Every

leaving 04:30 Odd 04:30 Every

blast 05:00 Odd 05:00 Every

ventilation 05:15 Odd 05:15 Every

preparation 06:00 Every 06:00 Every 06:00 Every 06:00 Every

run 06:45 Every 06:45 Every 06:45 Every 06:45 Every

lunch break 10:00 Every 10:00 Every 10:00 Every 10:00 Every

run 11:00 Every 11:00 Every 11:00 Every 11:00 Every

leaving 13:30 Every 13:30 Every 13:30 Every 13:30 Every

blast 14:15 Every 14:15 Every 14:15 Every 14:15 Every

ventilation 14:30 Every 14:30 Every 14:30 No 14:30 No

preparation 15:00 Every 15:00 Every 20:30 Even

run 15:45 Every 15:45 Every 21:15 Even

lunch break 18:00 Every 18:00 Every

run 19:00 Every 19:00 Every

leaving 22:30 Every 21:00 Every

blast 23:15 Every 22:00 Every

ventilation 23:30 Every 22:15 Every

Table 20: Detailed activity times in Renström mine (Shift sheet in excel)

Activity Place Mine truck Highway truck

Loading (+manoeuvring) 4,50 min (+ 0,83 min) 2,10 min (+ 0,5 min)

Dumping (+manoeuvring) Crusher 1,5 min (+ 0,83 min) 0,66 min (+ 0,5 min)

Backfilling 2 min (+ 0,83 min) 1 min (+ 1 min)

Meeting (+manoeuvring) Empty meeting 1,1 min (+ 0,83 min) 0,8 min (+ 0,3 min)

Table 21: Average activity duration for haulage by Highway truck and Mine truck

The data shown in Table 20 is gathered from Renström mine and the data in Table 21 is

gathered from the activity time study done in Renström mine in 2010. In the simulation

model, the activity manoeuvring has not been shown as an image but manoeuvring time has

been added on the activities that are coming before or after manoeuvring such as dumping,

loading and meeting. Average activity times are estimated according to average height is

371m (distance between crusher and rooms) and gradient is 1:8.

There are two haulage activities in the mine; ore transportation to the crusher and

backfilling. The waste material is mostly used as backfilling material.

Level Drift Faces Blast ID Dependency Cycle

ID

Sched_date Quality Tonnes

1165 H1165_Graberg H1165Inslag 15 001 0 2 2010-10-21 Waste 78

1165 H1165_Graberg H1165Inslag 15 002 15 001 2 2010-10-21 Waste 77

1165 H1165_Malm H1165_Lins_3 15 006 0 2 2010-09-02 Ore 312

1165 H1165_Malm H1165_Lins_3 15 007 15 006 2 2010-09-13 Ore 299

1165 H1165_Malm H1165_Lins_3 15 008 15 007 2 2010-09-15 Ore 305

Table 22: Ore and waste transportation schedule according to date and room (Blasting sheet in excel)

In order to start blasting, the program first checks the date and then the dependency. For

example, before H11165Inslag which has Blast ID 15001 is blasted, Blast ID 15 002 cannot

67

be blasted. Cycle ID column tells us to follow cycle type which has been shown in Table 22.

The rooms are available after mentioned dates (scheduled date column) for loading and

transportation. The waste material is transported to the backfilling rooms according to Table

23.

Level Backfilling Faces Sched_date

(available from)

Quality Tonnes

1255 H1255_Fyll H1255_lins_2 2010-09-01 Fill 1 975*

1165 H1165_Fyll H1165HoVa 2010-10-06 Fill 5 575

1165 H1165_ Fyll H1165_Va 2010-10-22 Fill 925

920 S920_ Fyll S920_Ho 2010-09-06 Fill 4 990

920 S920_ Fyll S920_Ho 2010-09-20 Fill 2 590

920 S920_ Fyll S920_Va_fack_2 2010-09-05 Fill 5 257

920 S920_ Fyll S920_Va_fack_2 2010-09-28 Fill 1 928

1180 V1180_ Fyll V1180_Ho 2010-09-28 Fill 2 517

Table 23: Backfilling rooms (Backfilling sheet in excel)

*Remaining backfilling from previous period. It is available at the start of simulation.

In Table 23, backfilling rooms are shown according to backfilling start date and tonnage.

The backfilling rules are that the nearest room must be selected according to earliest

backfilling date and no other room can be filled until that room is filled and completed. For

instance, in AutoMod, the first backfilling activity is in 1st of September and the backfilling

material tonnage is 1975 tonnes. After this room is filled and completed, the next room will

be S920_va_fack_2 which is available from 5th

of September. Drift or backfilling column is

the station name defined in AutoMod and Faces column is the real name of the rooms. Due

to short distances between these backfilling rooms, only one common station has been

created in AutoMod to make the model simpler.

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The simulation time and start date can be arranged as preferred from general input sheet.

In the same sheet, maximum number of haulers for each loader can also be changed together

with the activity durations for loading, dumping and meeting (Table 24).

Simulation time 9 weeks

Start date 2010-09-01

Start day Wednesday

Maximum number of haulers for each load 2

Time +/-

Loading mine truck 00:05:20 00:01:00

Loading highway truck 00:02:26 00:01:00

Dumping time for mine truck at crusher 00:02:20 00:00:30

Dumping time for highway truck at crusher 00:01:10 00:00:30

Dumping time for mine truck at backfill 00:02:50 00:01:00

Dumping time for highway truck at backfill 00:02:00 00:01:00

Dumping time for loader at backfill 00:01:00 00:00:30

Min Average Max

Time loss at meeting for mine truck 00:00:05 00:00:10 00:02:00

Time loss at meeting for highway truck 00:00:05 00:00:10 00:02:00

Table 24: Loading, dumping and meeting duration for haulage vehicle (General Input sheet in excel)

69

APPENDIX III

Output data from simulation model

70

In the output data section of the excel interface, the results according to input data put into

the model are presented. For each run, it is better to save the results in another excel file

because of the fact that it is overwriting the results.

First of all, the model is delivering a log file of activities after every run according to

selected machines in Machine sheet (Input data section). The main purpose with this log file

is to have a quick look over the production activities by using a Gantt chart. Each activity is

presented by different colour (Figure 10).

Figure 10: The view over activities displayed in a Gantt chart (Gantt Browser)

71

The second sheet is Vehicles. In this sheet the titles below are presented.

Working

Delayed

Idle

Unscheduled maintenance

Scheduled maintenance

Out of plan

Motor time

Each title is consisting of some activities. To illustrate, Transport up, dump, transport down

and load is in working group. In order to know the details about these titles see Appendix

III.

The summation of activities for each title is presented according to each vehicle used in the

mine (Figure 11).

Figure 11: Vehicles sheet in excel

72

The third component of the output section is Haulers. In this sheet following titles are

presented for Mine trucks and Highway trucks.

Total tonnes ore

Total tonnes waste

Frequency ore (how many times ore is hauled or dumped to the crusher)

Frequency waste (how many times waste is hauled or dumped to the crusher)

Average cycle time ore

Average cycle time waste

Frequency failure (how many times vehicle has broken down)

Average time failure

In Figure 12, scheduled blast dates and actual blast dates are shown.

Figure 12: Scheduled and Actual blasting dates for each blast (Cyclelog sheet)

The vehicles sheet in Figure 13 is presenting the calculation for each vehicle in the mine

according to the titles below.

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Availability (=Available / Scheduled hours)

Utilization (=Operation/Available)

Effectiveness (=Working/Operation)

Overall Utilization (=Utilization*Effectiveness or Working/Available)

Reliability (=e^(-t/MTBF))

Maintenance burden (=Maintenance/Working)

MTBF (=Working/No. of shutdowns)

MTTR (=Unsch. Maint /No. of shutdowns)

Figure 13: The vehicles sheet in excel (the values are not representative)

74

APPENDIX IV

Flowchart of the activities in Renström mine

and the logic behind the model in AutoMod

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