2007:083
M A S T E R ' S T H E S I S
An Analysis of the
boulder-handling system at the Kiruna Mine, LKAB
Miriam Drakenberg
Luleå University of Technology Master Thesis, Continuation Courses Applied Geosciences and Rock Mechanics Department of Civil and Environmental Engineering Division of Soil Mechanics and Foundation Engineering
1. ABSTRACT
This thesis is part of the requirements for the degree of Master of Science in Applied Geosciences and Rock-mechanics. The purpose was to analyse the rock-breaking operations by the five different remote-controlled rock-breakers that are located at different shafts and levels in the Kiruna mine operated by LKAB. The result of this analysis was that a large amount of data considering the obstacles that the rock-breakers have to destroy came to LKAB’s knowledge. Data such as volumes and material, shapes and number of contributions and sizes of the obstacles were found. According to the gathered data approximately 65 obstacles covers the shaft-entrances each day and the rock-breakers need in average 152 minutes for their daily operations. Instead of having almost 90 percent of the boulders made of waste-rock, as was assumed, the data showed that almost half of the obstacles were made of ore.
Data about the operations that the rock-breakers performed (such as different times and types of operations) and some data about the effect the rock-breakers have on the production- chain (accessibility of the rock-breakers, the affect on the production and yearly production- losses) were also discovered. One result was that the average time for the different types of rock-breaker operations became known. It takes in average 5 minutes for a rock-breaker to destroy a boulder, roughly 2 minutes to destroy a bridge and 1.1 minutes to clean up around the shaft-entrance. It also became known that the obstacles made of waste-rock took longer time to destroy than the ones made of ore; 58.5% against 34.8 % of the total time needed for operations. Another result was that the accessibility of the rock-breakers was 68.6% and that LKAB yearly looses almost 420’000 ton due to short production-breaks in the five shafts covered by this work.
LKAB had before this study mostly had assumptions to work with and wanted to change that.
The gathering of the data consisted of several different operators filling in report-sheets of paper that later were translated and complied into a database in Microsoft Excel. The information from this database was then used to obtain the anticipated result.
.
TABLE OF CONTENTS
1. ABSTRACT ... 1
2. TASK DEFINITION ... 6
3. INTRODUCTION ... 8
4. THE KIRUNA MINE... 10
4.1. THEORE... 10
4.2. THEEXCAVATIONPROCESS... 10
4.3. THEPRODUCTION-CYCLE... 11
4.3.1. WORK-TEAMS... 11
4.4. THEROCK-BREAKINGSYSTEMATLKAB... 12
4.4.1. REMOTE-CONTROLLED HANDLING ... 13
4.4.2. MANUAL HANDLING ... 13
5. COMPUTER PROGRAMS... 14
5.1. EXCEL... 14
5.2. ASPENTECH... 14
5.3. GIRON... 15
6. METHODS AND MATERIALS USED TO COLLECT DATA ... 16
6.1. METHODSTOCOLLECTDATA... 16
6.1.1. INFORMATION GATHERED FROM THE OPERATORS ... 16
6.1.2. METHODS TO GATHER INFORMATION FROM COMPUTER-PROGRAMS ... 17
7. RESULTS... 18
7.1. GENERALRESULTS... 18
7.1.1. TIMES ... 18
7.1.2. BOULDERS AND BRIDGES ... 21
7.1.3. SHAPE ... 21
7.1.4. SIZE... 23
7.1.5. NORMAL DISTRIBUTION OF BOULDER-SIZES... 24
7.1.6. MATERIAL... 27
7.1.7. VOLUME ... 27
7.1.8. OPERATIONS ... 29
7.1.9. AFFECT ON THE LHDs... 29
7.2. RESULTSINDETAIL ... 30
7.2.1. TIME ... 30
7.2.2. BRIDGES AND BOULDERS ... 31
7.2.3. AFFECT ON THE LHDs... 32
7.2.4. OPERATIONS ... 32
7.2.5. MATERIAL... 33
7.2.6. VOLUMES... 33
7.2.7. SHAPES ... 34
7.2.8. POSSIBILITIES... 36
7.2.9. SIZE... 37
7.2.10. ACCESSIBILITY... 39
7.2.11. DEGREE OF UTILIZATION... 41
7.3. RESULTSFROMIP21... 43
7.4. RESULTSFROMEXCEL... 45
7.5. RESULTSOFPRODUCTION-LOSSES ... 45
7.5.1. LOSSES IN THE AREAS WITH AUTOMATIC LHDs... 46
7.5.2. LOSSES IN THE AREAS WITH MANUAL LHDs ... 47
8. DISCUSSION... 50
8.1. PROBLEMSTHATMAYHAVEINFLUENCEDTHERESULTS ... 50
8.1.1. SUGGESTIONS IN ORDER TO REDUCE THE CONTRIBUTIONS OF OBSTACLES... 51
8.1.2. SUGGESTIONS FOR FURTHER ANALYSES ... 52
9. ACKNOWLEDGEMENTS ... 54
10. REFERENCES ... 56
10.1. INTERNET... 56
10.2. BOOKS... 56
10.3. PERSONS... 57
10.4. OTHERSMEDIAS... 58
11. DEFINITIONS OF WORDS ... 59
12. APPENDIX I ... 60
13. GENERAL ... 60
13.1. TIMES ... 60
13.2. VOLUMEVERSUSTIME... 60
13.3. MATERIAL... 61
13.4. WAITINGTIMEFORTHELHD ... 62
13.5. OPERATIONS... 63
13.6. VOLUME ... 63
13.7. VOLUME VERSUS TIME VERSUS MATERIAL... 64
14. APPENDIX II... 66
15. AUTOMATIC VS MANUALLY... 66
15.1. TIME... 66
15.1.1. REMOTE: HANDLING TIME FOR BOULDER-VOLUME... 66
15.1.2. MANUAL: HANDLING TIME FOR BOULDER-VOLUME ... 67
16. APPENDIX III ... 70
17. IN DEPTH ... 70
17.1. BRIDGESANDBOULDERS ... 70
17.1.1. GENERAL ... 70
17.1.2. AUTOMATIC... 70
17.1.3. MANUAL ... 71
17.1.4. SHAFT 122 ... 71
17.1.5. SHAFT 123 ... 71
17.1.6. SHAFT 194 ... 72
17.1.7. SHAFT 282 ... 72
17.1.8. SHAFT 453 ... 73
17.2. WAITINGTIME ... 73
17.2.1. GENERAL ... 73
17.2.2. AUTOMATIC... 73
17.2.3. MANUAL ... 74
17.2.4. SHAFT 122 ... 74
17.2.5. SHAFT 123 ... 74
17.2.6. SHAFT 194 ... 75
17.2.7. SHAFT 282 ... 75
17.2.8. SHAFT 453 ... 75
17.3. OPERATIONS... 76
17.3.1. AUTOMATIC... 76
17.3.2. MANUAL ... 76
17.3.3. SHAFT 122 ... 76
17.3.4. SHAFT 123 ... 77
17.3.5. SHAFT 194 ... 77
17.3.6. SHAFT 282 ... 77
17.3.7. SHAFT 453 ... 78
17.4. MATERIAL... 78
17.4.1. GENERAL ... 78
17.4.2. AUTOMATIC... 78
17.4.3. MANUAL ... 79
17.4.4. SHAFT 122 ... 79
17.4.5. SHAFT 123 ... 79
17.4.6. SHAFT 194 ... 80
17.4.7. SHAFT 282 ... 80
17.4.8. SHAFT 453 ... 80
17.5. VOLUMES ... 81
17.5.1. AUTOMATIC... 81
17.5.2. MANUAL ... 81
17.5.3. SHAFT 122 ... 82
17.5.4. SHAFT 194 ... 82
17.5.5. SHAFT 453 ... 82
17.6. SHAPES... 83
17.6.1. GENERAL ... 83
17.6.2. SHAFT 123 ... 83
17.6.3. SHAFT 194 ... 84
17.6.4. SHAFT 453 ... 84
17.7. POSSIBILITIES ... 84
17.7.1. GENERAL ... 84
17.7.2. SHAFT 122 ... 85
17.7.3. SHAFT 123 ... 85
17.7.4. SHAFT 194 ... 86
17.7.5. SHAFT 282 ... 86
17.7.6. SHAFT 453 ... 87
17.8. SIZE... 87
17.8.1. SHAFT 122 ... 87
17.8.2. SHAFT 123 ... 88
17.8.3. SHAFT 194 ... 88
17.8.4. SHAFT 453 ... 89
17.9. TIME... 89
17.9.1. GENERAL ... 89
17.9.2. AUTOMATIC... 90
17.9.3. MANUAL ... 91
17.9.4. SHAFT 122 ... 91
17.9.5. SHAFT 123 ... 92
17.9.6. SHAFT 194 ... 93
17.9.7. SHAFT 282 ... 94
17.9.8. SHAFT 453 ... 95
17.10. DEGREEOFUTILIZATION ... 95
17.10.1. GENERAL ... 95
17.10.2. SHAFT 122 ... 96
17.10.3. SHAFT 194 ... 96
17.10.4. SHAFT 453 ... 97
18. APPENDIX IV ... 98
18.1. FORMUSEDFORCOLLECTIONOFDATA ... 98
19. APPENDIX V... 99
19.1. PICTURES ONLHDS... 99
20. APPENDIX VI ... 100
20.1. NUMBEROFDAILYOPERATIONSINEACHSHAFT... 100
20.2. GRAPHS FROM IP21 ... 100
2. TASK DEFINITION
The purpose of this thesis was to:
• Describe the handling of the boulders with times and other data
• Collect data about the process
• Assemble the process-data (operation-times etc) in a way it can be used for further analysis, e.g. as a database in an automatic model
• Analyse frequencies and sizes on boulders with help of a combination of pictures and other available data
• Analyse data in order to discuss effects of changes in the production-system
• Produce a disturbance-model with new decisions-criteria based on the data Boundaries for this thesis:
• This work is limited to only deal with the process of rock-breaking. Other parts of the process, such as blasting, charging, loading are not a part of this thesis.
• This work is limited to identify factors that can affect the production in the loading- process.
• This work will only deal with the handling of boulders in LKAB’s Kiruna Mine.
LKAB’s mine in Malmberget is not a part of this thesis.
• This work will only deal with rock-breaking-operations where the entering shaft has a middle beam.
The analysis involves collection of data and if time is available the addition of historical data.
Activities and accomplishments:
• Collection of data
• Analysis of data
• Studies of literature: statistical methods, excavation methods etc
• Identification of interesting sensitivity-analyses and other scenarios.
• Sensitivity-analysis of data
• Collect all recommendations and results
• Write a report
• Presentation at LTU and LKAB The following variables were analysed:
• Cycle-times- different operations (e.g. breaking – bridges)
• Accessibility of the rock-breaker
• Degree of usage of the rock-breaker
• The share of boulders and bridges
• Average operating time per boulder
• Average boulder-size
• Frequency of different boulder-sizes (based of information from computer-images)
Halfway through the thesis was an agreement reached that an automatic model would be a part of this thesis. The model would be using the collected data and data about the rock- breakers from LKAB’s log-data program Aspen Tech. The time for attempting to produce the model would come from the remaining time for data-collection to the thesis. In addition to this would some data about the effect rock-breakers had on the LHD’s (Load-Haul-and-Dump minetrucks, for pictures on these machines see appendix V) also be a part of the thesis.
3. INTRODUCTION
The focus of this report is to analyze the operation of five rock-breakers at LKAB’s Kiruna Mine in order to find out more about the situation. LKAB is today trying to maximize the operation-time for the rock-breakers to 2 minutes. They want to see if it is possible and even necessary to do this in order to avoid disturbances of the production. This is due to the fact that the digit was taken from thin air as there is no real data about the rock-breakers.
Prior to this study, only the operators that are operating the machines knew something about the situations that they have to face during a work-day. Only they had the rough knowledge about the common sizes of the boulders, what the mean-operating time could be and in what shaft boulders were most common and if there were any differences between the shafts. They also had some rough knowledge about the differences between the three rock-breakers that are placed in shafts that are only dumped in by manually driven LHDs (Load Haul Dumper) and the remaining two rock-breakers that are placed in areas where automated LHDs unload their cargo. This also means that each operator had based their knowledge upon personal experience and references, so the answers on the questions hinted at above could vary a lot depending on which operator was answering.
No one had any real knowledge about what the accessibility and the degree of utilization of the machines; all those assumptions were based on more or less qualified guesses.
4. THE KIRUNA MINE
LKAB is a company that is wholly owned by the Swedish state. It has more than 3´500 employees worldwide. The company was founded in the northern part of Sweden in 1890.
Today it has become an international supplier with mines and production-facilities all over the world. The main assets are the magnetic iron-ores that are excavated in northern Sweden, ore that is mostly sold to European steel-mills, but also to markets in Africa, Middle East and Southeast Asia (see www.lkab.com).
4.1. THE ORE
The ore that is excavated in LKAB Kiruna-mine is located at and under the town Kiruna, in the north part of Sweden. The approximately 4 km long and 80 m wide singular slice of magnetite extends downwards to an estimated depth of 2 km. It has an inclination of almost 60 degrees.
The mining takes place from the former main-level that was placed at 775 meters down to today’s main-level at 1045 meters below ground. A new main-level are already being prepared at roughly 1300 meters below ground. LKAB counts that they are mining about 23 Mt crude ore each year. (See www.lkab.com).
4.2. THE EXCAVATION PROCESS
LKAB extracts the ore by using a mining-method called sublevel caving. This method is according to Hartman & Mutmansky (2002) applicable to near-vertical deposits and the ore- body in Kiruna falls within the frames for suitable ores. The main-principle for this method is that the mining progresses downwards when the ore between the regular spaced sublevels overhead is excavated. The mining starts with drilling each sublevel full of holes in a regular spaced fan-pattern that will be blasted from the hanging-wall of the topmost sublevel. The ore is then mucked out and the removal of the ore causes the surrounding waste-rock to cave in
(data is available at http://www.miningbasics.com/html/shrinkage_stoping_mining_metho.php). This will in turn
cause the amount of waste-rock in the excavated ore to increase with each load. When the amount of waste-rock reaches a certain level, the blasting and loading of the next fan begins (see http://www.britannica.com/eb/article-81281/mining). Figure 1 shows the method in a simple way.
Figure 1: Sublevel caving method. [http://www.britannica.com/eb/article-81281/mining]
4.3. THE PRODUCTION-CYCLE
The production-cycle in the mine is simple and starts with the drilling of a new set of blast- holes. These holes are then charged and blasted. After some time of ventilation, the safety- work of bolting and scaling the walls and roof of the shaft takes place. After that the LHDs start loading the excavated material and finally shotcrete is added as extra safety for the next drilling-set (Forsman, ”Bergbyggnadsteknik”, 2003).
The production-cycle for the LHDs consists of the machine filling its scoop, hauling the cargo to the shaft, dumping it into the shaft and returning to the excavation place for the next round. This cycle takes around 6 to 7 minutes.
The loading will affect most on the results of this analysis. This is because if there were no loading there would not come any boulders that needed to be destroyed. However all operations performed by the rock-breakers can affect the production in a more or less negative way. The reason is that every last operation performed by the rock-breakers will be because the entrance of the shaft is blocked or too untidy for the LHD-driver to see where to unload.
And since the LHDs have to wait while a rock-breaker is operating, the entire production to a shaft has to be put on wait until the rock-breaker cease all movements.
4.3.1. WORK-TEAMS
LKAB has a system of five different work-teams working in shifts every day the year around. As presented below there are three different work-teams on duty each week, while the two remaining teams are off-duty. During weekdays a full-time rock-breaker operator
operates the five remote-controlled rock-breakers. During the other times, one of the six other operators (three loaders, two operators that are filling up the underground-trains and one train- operator) volunteers to destroy the boulders. The full-time rock-breaker-operator is not a member in any work-team, but might, according to his own statement, lend a hand to either team if needed.
Table 1: Schedule for the work-teams.
Week Mornings Afternoons Nights Weekends
1 06:00-14:00 - - -
2 - 14:00-22:00 - 06:00-18:00
3 - - - -
4 - - 22:00-06.00 18:00-06:00
5 - - - -
Table 2: Schedule for the professional rock-breaker.
Week Daytime Other time
All, except vacation-time 06:00-14:48 -
4.4. THE ROCK-BREAKING SYSTEM AT LKAB
The rock-breaking situation today is simple. A LHD takes the extracted ore or waste rock to a shaft which leads the rock through an ore passage to the main level, see Figure 1 and 2. At the main-level at 1045 meters below ground the rock are loaded onto trains and taken further into the production-process. According to Börje Andersson at LKAB has the shaft an entrance opening of 2,5 x 1,5 meters but a beam in the middle further decreases the size of the boulders which can pass through down to 1,5x1,16 meters. All boulders above this size have to be destroyed so they can pass through. The boulders can be dealt with in two different ways; by a remote-controlled rock-breaker or by manual handling on site.
To avoid interruption in the production process the obstacles that get caught at the shaft entrance need to be removed preferably within the time it takes for the LHD to come back with another load to the shaft, which takes around 6 to 7 minutes. The time is even less if there are several LHDs loading into the same shaft.
Figure 2: schematic picture over the rock-breaker and shaft entrance. (Billing & Hellström). The picture has been slightly modified.
4.4.1. REMOTE-CONTROLLED HANDLING
This method of dealing with boulders means that a remote-controlled rock-breaker is stationed beside the entering-shaft and destroys the boulders with a hydraulic hammer. Video- cameras stationed at these shaft-entrances send real-time images (see colour-images in figure 2) to a wide-screen from where the operator who operates the rock-breakers always can view all the shafts at the same time. The operator then has the ability to on another, smaller screen choose a shaft and control the rock-breaker on this smaller screen.
Today the Kiruna mine has two stations where an operator can manoeuvre the remote- controlled rock-breakers. Both of them are stationed in the same room on the sixth floor in the headquarters. All five rock-breakers in this thesis are remote-controlled. It is only from this method of destruction of obstacles that data are gathered.
4.4.2. MANUAL HANDLING
When a remote-controlled rock-breaker has failed to destroy a boulder for some reason, an LHD usually removes the boulder from the shaft-entrance and take it to a separated chamber where it can be divided into smaller rocks with the help of explosives. When it is impossible to remove the obstacle, the blasting of it will take place at the shaft-entrance. Another manual method is to bring a mobile rock-breaker or, if there is a fault in the transmission in either video-camera or in the automatic control, manually take control over the remote-controlled rock-breaker at the site and destroy the obstacle. These methods happen seldom and are not a part of this study.
Rock-breaker Obstacle
Shaft entrance Shaft to ore-passage
5. COMPUTER PROGRAMS
In this study different computer-programs were used. Excel was used as the data-base where all information was collected. Two other programs; Aspen Tech and Giron were used to collect log-data from.
5.1. EXCEL
Microsoft Excel is probably one of the most well-known calculation-programs in the world today. It is a part of Microsoft office package together with Word, Outlook, PowerPoint, Access and Publisher. Several different versions of the program have been used in this study;
from Excel 2000 to Excel 2003, but this have not had any influence of the results in the thesis.
5.2. ASPEN TECH
LKAB uses a program called Aspen Process Explorer (v 6.0 vs Flexgrid pro 7.0 © 2000 Aspen Technology), which consists of three parts; a Process Explorer, a Process Graphics Editor and a Tag Browser1. This program collects log-data in real-time from different machineries and shows it as graphs, either in the program or in Excel since the program is integrated with the Microsoft Windows® environment. The company homepage says that the program makes the routine engineering easier. The process of comparing large amounts of data becomes easier as the program uses already familiar concepts such as the scroll bar and a calendar for selecting dates. The graphic charts of the data (both current and historical values) facilitate the process of understanding and responding to changes in the process.
The company homepage also says that the idea behind the program was to make it easy to organize a vast amount of information about the process, in both historical time and real-time, and to present it so it in an easy way could be used to improve the process.
InfoPlus.21 (or IP21 for short) is the tool that this program uses in order to collect data in real- time. It is described on Aspen Tech’s homepage as followed:
“ (InfoPlus.21) helps process manufacturers improve the flow of information plant- wide through its integration with supply chain and ERP systems. Functioning as the -- interchange -- between these systems and providing detailed plant operations information to plant managers and engineers -- information that ultimately yields improved engineering workflow processes and control strategies (e.g., to prevent upsets, increase capacity or simplify environmental regulation compliance), as well as enhanced decision support, customer service, cost-efficiencies and operating performance.”
1 Information collected at LKAB, Kiruna on one of their computers.
Quote is taken from www.aspentech.com
This thesis handles data from five different rock-breakers and each and every machine has log-data for everything from oil-pressure and oil-temperature to different time-measures. Each parameter IP21 collects data about has a special name, called a tag. If need arises to control how much time the water-pump in the rock-breaker on level 665m and in shaft 122 has been activated there’s the possibility to enter the whole name of the tag: KG100HH004KQ001 into the Process Explorer and the Process Graphic Editor. The Tag Browser makes it easy to navigate through all tags that are connected to each machine. It simply lists every tag for all rock-breakers with a tag-name and a short description about the tag. Each set of machineries has its own name; rock-breakers are gathered under the tag KG100HH and each specified rock-breaker has its own number, the machine in the example above have the number 004 and the rest of the tag-name is for how long the water-pump has been activated.
The Process Graphic Editor simply produces a graph based on the data taken from the Process Explorer when it is given a name from the Tag Browser. This graph can run over an optional span of time. Some examples of the graphs collected from IP21 can be found in Figures 125-127 in appendix VI.
5.3. GIRON
LKAB uses a computer-program named Giron (v 01.068), designed by Softcenter2 to collect data from their automatic LHDs. This program is adapted to LKABs computer-net. It is not, as Aspen Tech, a program that automatically collects log-data, but a program where planned values are compared with the real values. The program is updated on daily basis with new information about the LHDs (such as disturbances, maintenance, lack of personal, time standing and time producing) and data about the production (such as from what location the rock is taken from, the theoretical goal, the achieved goal and amount of ore and waste-rock that has been produced).
2 Information gathered at LKAB, Kiruna and their computers.
6. METHODS AND MATERIALS USED TO COLLECT DATA
All data were collected at LKABs facilities in Kiruna and at the department of PCRB3 (Production Central Raw-material Manufacturing). Data about the rock-breakers reaches from the 16th of January 2007 to the 3rd of April 2007, the data about rock-breakers and LHDs only reaches between 16th of January, 2007 to 16th of March, 2007.
The shafts that data were collected from are:
• Shaft 122 at level 665 meters below ground. Loaded by automated LHDs.
• Shaft 123 at level 691 meters below ground. Loaded by manually driven LHDs.
• Shaft 194 at level 878 meters below ground. Loaded by manually driven LHDs.
• Shaft 282 at level 907 meters below ground. Loaded by manually driven LHDs.
• Shaft 453 at level 878 meters below ground. Loaded by automated LHDs.
The time for this study was divided somewhat equally between the parts the thesis consists of.
Between January and March were data collected at LKAB. In March began the attempt to create an automatic program while the gathering of data from the rock-breaker operators continued. The attempt to write a program, which ended in May, took place both in Kiruna and Luleå. The time that was left was to be used to write the report.
6.1. METHODS TO COLLECT DATA
In the beginning of the work it was decided that data should be collected both from the operators and from the computer-program IP21. During the progress of the study questions about the interaction between the rock-breakers and LHDs were asked and therefore some data about the LHDs from the computer-program Giron was also added.
6.1.1. INFORMATION GATHERED FROM THE OPERATORS
The data were collected from the operators by letting them taking notes on papers every time they operated a rock-breaker, these notes was later enter manually into Excel, as Excel was the program chosen to be the database in this case. The paper-notes consisted of information about:
1. The date
2. The number of the shaft
3. What type of operation was performed
4. The type of material the obstacle consisted of.
5. The volume of the boulder/boulders.
6. Number of boulders.
7. The measures of the boulder 8. The shape of the boulder/boulders.
3 Swedish translation: Produktion Central Råvaru Beredning
9. The approximate time it took to clear the shaft
10. Whether the LHDs have to wait during the operation or not A copy of the form used can be found in Appendix IV.
6.1.2. METHODS TO GATHER INFORMATION FROM COMPUTER-PROGRAMS
All information from the programs where gathered manually and entered into Excel.
From Giron data about the degree of disruption for the LHDs was taken. These daily values, which were in percent, were later transformed into the LHDs accessibility for each day.
In the initial stage of the work it was thought that the program Aspen Tech could give all the times about the operations the rock-breakers performed. The times the operators entered would only serve as a back-up. This was partly to make sure that the right time matched the right operator-entry. But also to check if every operation was entered by the operators so an automation of the program could be prepared. However, a number of problems emerged resulting with the fact that Aspen Tech could not be used in its current state.
7. RESULTS
7.1. GENERAL RESULTS
In general the data from the shafts were collected over a time-period of 77 days. The LHDs did sometimes not load into a certain shaft (or at least the shaft did not have any registered obstacles during some days). This provided the basis for some interesting results such as the average number of obstacles that statistically are expected in each shaft.
The total amount of obstacles in each shaft and the number of days when there were no loading into that specific shaft are presented in Table 8, appendix I. The following table in appendix I (Table 9) presents the calculated value for the most active shaft that LHDs are loading into together with the statistical number of obstacles each shaft has during a day.
Shaft 123 turned out to be least used as it had both the highest amount of days without any loading and the lowest amount of operations performed by the rock-breaker. The rest of the shafts are rated in the second column in Table 3 below between the two values set by shaft 123 and shaft 453 that is the most active shaft.
Listed also in Table 3 are the top 5 shafts with the highest amount of obstacles per day when there is loading into the shafts. The shaft with the highest amount of obstacles is shaft 282 with an average of 14.5 obstacles each day the LHDs dump cargo into the shaft. This is followed by shaft 453, shaft 194, shaft 122 and lastly shaft 123 with the least average value of 5.5 obstacles each day there is loading into the shaft.
Table 3: The top 5 lists when it comes to most active shafts, highest amounts of obstacles and statistically daily amounts of operations performed in a specific shaft
Shaft Top 5 of the most active shafts when it comes to being used by LHDs
Top 5 when it comes to the highest amount of obstacles per day the LHDs are loading into the shaft
Average amounts of operations each day the LHDs are loading into the shaft
122 2 4 8,6
123 5 5 5,5
194 4 3 8,9
282 3 1 14,5
453 1 2 13,3
7.1.1. TIMES
The daily variations in time between the rock-breakers can be seen in Figure 3. The highest noted amount of time used by the rock-breakers is roughly 600 minutes, which was recorded on the 2nd of February. The average required time the rock-breakers need for their daily operations is 152 minutes.
0 100 200 300 400 500 600 700
15-jan 22-jan
29-jan 05-feb
12-feb 19-feb
26-feb 05-m
ar 12-m
ar 19-m
ar 26-m
ar 02-apr DATE
TOTAL OPERATIONTIME USED EACH DAY MINUTES
Figure 3: Daily accumulated times for all five rock-breakers
The general times for each operation the rock-breakers performs varies between slightly above 5 minutes for rock-breaking and 2 minutes for removal of bridges down to 1.1 minutes for cleaning round the entrance of the shaft, as can be seen in Figure 4.
5,1
1,9
1,1
0,0 1,0 2,0 3,0 4,0 5,0 6,0
ROCKBREAKING STIRRING CLEANING
TIME IN MINUTES
Figure 4: Average time per operation for different types of operations
In Table 10, appendix I and in Figures 107 to 108 in Appendix III are different times for a single operation viewed in maximum, minimum and average time-graphs. One thing to point out are in Figures 5 and 6 below where the accumulated times are collected for the areas with automatic LHDs and the manual LHD areas. The two rock-breakers with automatic LHDs end up with a total time around 4500 minutes while the three rock-breakers with manually driven
LHDs needs 7000 minutes. This means that the rock-breakers in shafts 123, 194 and 282 each takes roughly 80 minutes longer to perform during the time-period data were collected.
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000
12-jan 22-jan 01-feb 11-feb 21-feb 03-mar 13-mar 23-mar 02-apr DATE
TIME IN MINUTES
Figure 5: Accumulated times for the shafts with automated LHDs
0 1000 2000 3000 4000 5000 6000 7000 8000
08-jan 18-jan 28-jan 07-feb 17-feb 27-feb 09-mar 19-mar 29-mar 08-apr DATE
TIME IN MINUTES
Figure 6: Accumulated times for the shafts with manually driven LHDs
7.1.2. BOULDERS AND BRIDGES
Figures 7 and 8 show that on average 65 obstacles (mostly boulders) were in need to be taken care of by the rock-breakers each day during the 16th of January to 3rd of April.
0 50 100 150 200 250
12-jan 01-feb 21-feb 13-mar 02-apr DATE
NUMBER OF OBSTACLES
BOULDERS BRIDGES
Figure 7: The daily contributions of obstacles
0,0 20,0 40,0 60,0 80,0 100,0
12-jan 01-feb 21-feb 13-mar 02-apr DATE
PERCENT
BOULDERS BRIDGES
Figure 8: The daily contributions of obstacles in percent
7.1.3. SHAPE
Bridges have a higher percent of round and flat shapes than the boulders. But as Figures 9 and 10 show, both boulders and bridges consist mostly of rocks of an angular shape. The statement that the angular shape is the most common shape is supported in Figure 11. The destruction of obstacles of angular shapes takes 57% of the total time used for rock-breaking- operations. Whereas the triangular shape, that according to the operators, takes the longest time to destroy4, only counts for 4.3% of the total time used for such operations.
4 This is due to the fact that it is harder to find a point where the hammer has enough friction to start the destruction of the boulder.
0 20 40 60 80 100 120 140 160 180
12-jan 01-feb 21-feb 13-mar 02-apr
DATE
NUMBER OF OBSTACLE
ROUND ANGULAR FLAT
TRIANGULAR
Figure 9: The daily contribution of boulders of a certain shape
0 5 10 15 20 25
12-jan 01-feb 21-feb 13-mar 02-apr
DATE
NUMBER OF BRIDGE
ROUND ANGULAR FLAT TRIANGULAR
Figure 10: The daily contribution of bridges of a certain shape
57,0
21,6
9,7
4,3 5,0
2,32 0,0
10,0 20,0 30,0 40,0 50,0 60,0
ANGULAR
ROU
ND FLA
T
TRIANGULAR COMB
INATION S
UNK NO
WN PERCENT OF THE TOTAL TIME USED . BY THE ROCK-BREAKERS
Figure 11: The percentage of time (of the total time used by the rock-breakers) it takes to destroy all boulders of a certain shape
7.1.4. SIZE
Over 6000 recordings of obstacle sizes were taken during the period the data were collected as can be seen in Figures 12 and 13. All were taken by operators that estimated the size from a computer-image. This means that 35% of the measurements are of sizes that theoretically should pass through the shaft and some (~2%) are of sizes that are even bigger than the room the shaft is located in. However, the most common size of boulders is around 0.5 – 1.5 meters.
0 100 200 300 400 500 600 700
0 0,2 0,4 0,6 0,75 0,9 1,1 1,3 1,5 1,7 1,8 2,1 2,3 2,5 2,7 3 3,5
METERS
NUMBER OF BOULDERS
Figure 12: The amount of boulders of a certain size.
0 2 4 6 8 10 12
0 0,2 0,4 0,6 0,75 0,9 1,1 1,3 1,5 1,7 1,8 2,1 2,3 2,5 2,7 3 3,5
METERS
PERCENT
Figure 13: Percentage of boulder sizes
7.1.5. NORMAL DISTRIBUTION OF BOULDER-SIZES
The normal distribution is a member of the family of distributions that are viewed as a bow.
It is an easy tool for the statisticians to work with as many different kinds of data are approximated well by it. This data can be both psychological and educational variables such as measures of reading ability, introversion and memory. Another reason why the normal distribution is important is that it both has an easy formula and that many different statistical tests, such as raw scores and percentiles, can be derived from it. The normal distribution is defined by two parameters called mean (μ) and standard deviation (σ) and these give the height f(x) for each known variable (x) (see formula 1). (Data are available at
http://davidmlane.com/hyperstat/A6929.html and http://davidmlane.com/hyperstat/normal_distribution.html).
The definition of the normal distribution used in this thesis is:
Formula 1: common normal distribution. (http://mathworld.wolfram.com/NormalDistribution.html)
By setting μ = 0 and σ = 1 in Formula 1 the formula for the standard normal distribution is given. An unpredictable normal distribution could be converted to a standard normal distribution by using the Formula 2 below:
2 2
) (
) ) ((
2 ) 1
( σ
μσ
π
dx X
e dx
x P
−
=
Formula 2: standardized normal distribution. (http://mathworld.wolfram.com/NormalDistribution.html)
The distribution that comes as a result of formula 1 will look like the distribution in Figure 14.
Figure 14: Normal distribution. The picture has been slightly modified.
(http://www.quicknet.se/hdc/ord/info/sigma.htm)
In this report and in Figure 14 the normal distribution has been trimmed to ±3σ. 99.7% is included within this rage as are shown below in the very unclear picture taken from Karin Dahmström’s (2005) book.
Figure 15: A very unclear picture of a normal distribution (Dahmström, page 241)
The normal distribution for LKABs obstacles is a result of the standard deviation 0.8 and a mean-value of 1.3 meters5. It leaves us with the distribution that crosses the y-axis between μ- 2σ and μ-σ as shown in Figure 16.
5 The calculations are based upon values without the boulders above 3.5 meters
μ
−3σ −2σ −σ σ 2σ 3σ
ca 68%
ca 95%
ca 99,7%
Figure 16: The theoretical normal distribution of boulder-sizes. The picture has been modified for this report. (http://www.ises.abo.fi/kurser/stat/8765/forelasning/kapitel10.htm)
Boulders with sizes above 3.5 meters have not been taken into consideration in the normal distribution calculation. This is because it is practically impossible for the LHDs to carry boulders above this size. The removed sizes did not affect the normal distribution that much as can be seen in Table 4.
Table 4: The values of LKABs normal distribution of boulder-sizes Sizes without the
largest boulders (those above 3.5 meters)
Sizes with the largest boulders (those above 3.5 meters)
μ-3σ -1,0 -1,2
μ-2σ -0,2 -0,3
μ-1σ 0,5 0,5
μ 1,3 1,4
μ+1σ 2,1 2,2
μ+2σ 2,9 3,1
μ+3σ 3,7 3,9
This means that the average-sized boulder is around 1.3 to 1.4 meters depending on whether the unreasonable large boulders6 are in the calculation or not. It also means that almost 95%
of all boulders have at least one side which is within the size of 0.5 – 2.1 meters.
6 Boulders above the size of 3.5 meters.
3.7
0.5 2.1 2.9
-1.0 -0.2 1.3
7.1.6. MATERIAL
Even if the percentage of boulders consisting of ore and boulders consisting of waste-rock is fairly the same (as can be seen in the more detailed results), the amount of time it takes to destroy them differs a lot. Boulders made of waste-rock takes 58.5% of the total time used by the rock-breakers while the boulders of ore only demands 34.8% as can be seen in Figure 17.
58,5
34,8
3,9 2,8
0,0 10,0 20,0 30,0 40,0 50,0 60,0 70,0
WASTE ROCK ORE MIXED ROCK UNKNOWN ROCK
PERCENT OF THE TOTAL TIME USED FOR OPERATING BOULDERS
Figure 17: The percentage of time (of the total time) used to destroy obstacles of a certain material
7.1.7. VOLUME
Volume is calculated by multiplying the two sides with the height, so the most ideal would have been if there had been three reported measurements of each boulder. But, this would be impossible to accomplish, as there seldom is only one single boulder that gets stuck at the entrance of the shaft. It would be even harder for the operators to guess the depth of the boulders than the sides. At the best there were two measurements noted down for a single occasion, in the worse case only one. The definitions for the volumes have been set by the rock-breaker operators during the first two weeks as they noted down the size of the obstacle.
These records of the size of the obstacle were multiplied and the unknown value(s) was put down as 1 m. Therefore all values for each operation have been multiplied with 1 and the result is categories as follows below:
Name Sides Volume
Large ~3 m 10 m3
Big ~2-3 m 5-10 m3
Small ~1-2 m 1-5 m3 Minor up to 1 m up to 1 m3
In some cases were no information about the boulders sizes noted down by the operator. In such cases the unknown value was not put to 1 but to 0 and are therefore not in the calculations.
6,8
4,6
2,7 1,6
12,5
5,8
4,3
2,2
4,1 3,9
2,8 2,0
0,0 2,0 4,0 6,0 8,0 10,0 12,0 14,0
LARGE BIG SMALL MINOR
VOLUME
TIME IN MINUTES
ORE
WASTE ROCK MIXED ROCK
Figure 18: the average time to destroy a boulder of a specific volume and material
Even if it is the boulders of the volume ‘large’ that should take most time both theoretically and according to Figure 18, it is actually the ‘small’ boulders that take almost half of the total time to destroy for the rock-breakers. If the ‘big’ boulders were taken into the summary these two volumes take two thirds of the total time used for the operations, as can be seen in Figure 19. (Small boulders 41.7 % + big boulders 24.6% = big and small boulders 66.3%)
17,8
24,6
41,6
8,9 6,6
0,4 0,0
5,0 10,0 15,0 20,0 25,0 30,0 35,0 40,0 45,0
LARGE
BIG
SM ALL
MINOR
COM BINATION
S
UN KN
OWN SIZ E
VOLUMES OF BOULDERS PERCENT OF THE TOTAL TIME USED BY THE ROCK-BREAKERS
Figure 19: The percentage of time to destroy boulders of a certain volume in general, compared to the total time used of the rock-breakers.
Figure 20 shows that the small volume is also the one that is most common to create bridges as it is reported in over 80% of the reports of combined volumes.
2,2 0,9
26,9 53,3 16,7
BIG TO LARGE SMALL TO LARGE MINOR TO SMALL SMALL TO BIG UNKNOWN
Figure 20: Percentage of volumes when it comes to combinations of different types of volume
7.1.8. OPERATIONS
When it comes to what type of operations the rock-breakers performs, it was assumed that most time was spent on actual rock-breaking. This was confirmed of the analysis. In general 94% of the activities consist of rock-breaking (83%) or the removal of a bridge (11%) as can be seen in Figure 21.
83%
11%
3% 3%
ROCKBREAKING
STIRRING CLEANING
COMBINATIONS OF OPERATIONS
Figure 21: Percentage of the total time needed by the rock-breakers that was used for different types of operations.
7.1.9. AFFECT ON THE LHDs
26% of the operations generate waiting-time for the LHDs. In some cases, this can be due to the rock-breaker-operator noticing the obstacle only minutes before the LHD came back with a second load.
0,0 20,0 40,0 60,0 80,0 100,0
12- jan
22- jan
01- feb
11- feb
21- feb
03- mar
13- mar
23- mar
02- apr DATE
PERCENT OF THE ROCKBREAKERS OPERATIONS EACH DAY
LHD WAITED LHD DIDN'T WAIT
Figure 22: The percentage of rock-breaker operations that affected the LHDs production-cycle each day
7.2. RESULTS IN DETAIL
The results for the areas with automatic LHDs and the areas with manually driven LHDs differ from each other. This is because the results from the shafts differ. The following part of the thesis takes a deeper look at these differences.
7.2.1. TIME
4,2
1,8
1,1
3,8 5,8
1,9
1,1
3,8
0,0 1,0 2,0 3,0 4,0 5,0 6,0 7,0
ROCKBREAKING STIRRING CLEANING COMBINATIONS OF OPERATIONS
TIME IN MINUTES
SHAFTS WITH AUTOMATIC LHDs SHAFT WITH MANUAL LHDs
Figure 23: comparison of the average operation-times for the shafts with automatic or manual LHDs
As Figure 23 above shows, the time it takes to do different kinds of operations in the shafts with manual LHDs are longer or equal to the same operations performed in the shafts with
automatic LHDs. This is most prominent when the task is rock-breaking as it takes 5.8 minutes in the ‘manual LHD’-shafts and only 4.2 in the ‘automatic LHD’-shafts. This difference may be due to the fact that the operators of the remote-controlled LHDs are able to communicate with the operator of the rock-breakers and warn about incoming obstacles, whereas the operators of the manually driven LHDs do not have this opportunity. They have to rely on the rock-breaker-operator to see the obstacle in time in order not to influence the production cycle too much. Another difference in the same line might be that the operator of the rock-breaker only have one ‘manual LHD’-shaft where (s)he can get any indication if the LHD has dumped the obstacle recently (the drivers of the automatic LHDs know mostly where their machines are in the work-cycle). In one of the shafts with manually driven LHDs, there are several steel-chains that hang in front of the entrance. They are there to make it easier for the LHD-driver to see where the entrance is. But because they always starts to swing after the LHD has been there, they also serves as an indication for the rock-breaker- operator to see if it would be a good idea to start handling the obstacle. If they are unmoving the LHD might come back with a new load within a couple of minutes.
The time-difference when it comes to the removal of bridges is smaller. The shafts with automatic LHDs need in average 1.8 minutes to clear the entrance, while the shafts loaded by manual LHDs in average need 1.9 minutes. The reason for this result might be that the contributions of bridges have been much smaller than the contribution of boulders.
The remaining figures in appendix II (Figures 52 to 55) shows the distribution between the times it takes for each area to handle a boulder of a specific volume and the average time for handling a single operation for the same boulder. The figures are summarized in Table 5 below. More graphs with times can be found among Figures 109 to 119 in appendix III, also Figure 56 in appendix II can be of interest as it views the average-operation times for the different shafts.
Table 5: Differences between different volumes of boulders
Boulder
volume Percent of total operation time
automated LHDs manual LHDs Time to destroy a boulder in minutes automated LHDs manual LHDs
Large 13.9 20.3 8.7 13.4
Big 29 21 5.0 5.7
Small 36.7 45.1 2.5 4.1
Minor 11.8 7.3 1.7 1.8
7.2.2. BRIDGES AND BOULDERS
As seen in Figures 57 to 64 in appendix III, both the ‘automated LHD’ and the ‘manual LHD’ areas have the same percentage of boulders versus bridges according to the data. The percentage of boulders in both areas was 89 % and the bridges counted for 10%. Therefore this was also the general division between boulders and bridges.
However, between the different shafts there were a lot of variations. Shaft 123 had the highest amount of bridges with 15% and 82% percent of boulders, whereas shaft 194 had the lowest amount of bridges with only 6% and 92% of boulders. The other results of the division in percent between bridges and boulders were as follows: in shaft 122 it was 12 % bridges and 87% boulders, in shaft 282 it was 11% bridges and 89 % boulders and lastly, in shaft 453 it was 9% bridges and 90% boulders.
7.2.3. AFFECT ON THE LHDs
As stated before, Figure 22 shows that in average 26% of all operations affect the LHDs in such grade that the production to that shaft is put on hold for a short time. This statement is based upon the data from Figures 65 to 72 in Appendix III. There is a difference between the areas with ‘manual LHD’ and ‘automatic LHD’ in such way that shafts with manual LHDs need the LHDs to wait in 30% of all operations while the rock-breakers finish the operations.
In the shafts with automatic LHDs the percentage is only 20.
The differences between the shafts were even bigger and varied between 7% in shaft 123 to 38% in shaft 282. This may due to the fact that shaft 123 was the shaft with least obstacles of all and shaft 282 was the shaft that had the most. Shaft 194 has the second highest percentage of operations where the LHDs need to wait for the rock-breaker with 26%, whereas the same kind of operations ends up with 18% for shaft 453 and 23% for shaft 122.
7.2.4. OPERATIONS
In both areas were destruction of rocks and the removal of bridges the most prominent type of operation, as can be seen in Figures 73 to 79, Appendix III. That rock-breakage is the most common type of operation also shows in Figure 24 below. The figure shows the percentage of operations in both areas.
65%
25%
10%
ROCKBREAKING STIRRING CLEANING
Figure 24: Percentage of operations done by the rock-breakers
Rock-breaking stands for 65% of all operation, 25% is removal of bridges and the rest is for cleaning. In areas with automatic LHDs; 58% of the operations are breakage of rocks, 27% is needed for the handling of bridges and 13% is noted down as cleaning. In the ‘manual LHDs’- shafts are 69% of the operations used for breakage of rocks, 17% is for bridges and 10% is for cleaning. The most untidy is shaft 123 which needs to use 20% of the operations to clean the entrance. Shaft 123 also has the highest percent of operations for removal of bridges.
Therefore the high amount of cleaning in shaft 123 reason is due to reasons such as bridges are messier than boulders. The shaft that has the least percentage of cleaning is shaft 282 with 8%. It is also the shaft that has least operations with bridges and uses 75% of all operations to destroy boulders.
