The fragment size distribution of Kiruna magnetite loaded...

Report 2008:P2 ISSN 1653-5006

Swedish Blasting Research CentreMejerivägen 1, SE-117 43 Stockholm

Luleå University of TechnologySE-971 87 Luleå www.ltu.se

The fragment size distribution of Kiruna magnetite loaded from a draw point – Evaluation and analysis of a full-scale test

Styckefallsfördelningen hos Kiruna magnetit från en utlastningsort – Utvärdering och analys av ett fullskaleförsök

Matthias Wimmer, Swebrec Joel Kangas, LKABFinn Ouchterlony, Swebrec

Universitetstryckeriet, L

uleå

Swebrec Report 2008:P2

The fragment size distribution of Kiruna magnetite loaded from a draw point - Evaluation and analysis of a full-scale test

Styckefallsfördelningen hos Kiruna magnetit från en utlastningsort - Utvärdering och analys av ett fullskaleförsök

Matthias Wimmer, Swebrec

Joel Kangas, LKAB

Finn Ouchterlony, Swebrec

Luleå February 2008, revised March 4, 2008

Swebrec - Swedish Blasting Research Centre

Luleå University of Technology

Department of Civil and Environmental Engineering • Division of Rock Engineering

i

The fragment size distribution of Kiruna magnetite Swebrec Report 2008:P2

SUMMARY

The objective of this investigation was to find out whether the Kiruna magnetite behaves like waste

rock from a blasting point of view. Our main conclusion is that the magnetite qualitatively behaves

like waste rock from a blasting point of view.

To do this we conducted a full-scale study of the fragmentation characteristics for blasted magnetite

ore from the SLC operation in Kiruna. For comparison we had access to model scale blasting data,

laboratory scale crushing and milling data, and historical full-scale data from the mine, albeit when the

scale of the SLC levels was much smaller than at the time of the investigation.

Historical sieving data (Maripuu 1968) does not show any irregularities in the breakage behaviour of

Kiruna magnetite and is thus comparable to fragmentation characteristics which might be expected to

apply for waste rock. The percentile size x50 varies within a wide range, but a trend of the changes of

x50 with increasing extraction rate could not be obtained.

The data of this study confirms that the material basically follows the NBC criteria within the fines

region (< 10 mm). The chemical composition of Maripuu`s samples differs from those of the study.

However, the minimum in the GGS plots coincides with the investigated samples and lies at x ~ 0.25

mm. A petrographic study considering different ore types would probably give information about

possible interrelations. The complete fragmentation distribution for our buckets yield an extremely

large variation for the parameter x50, within 14.3 – 278 mm, with an average of 86 mm, the same as for

Maripuu`s data. However, the shapes of the present sieving curves do not entirely fit the Swebrec

function. This is surprising as a deviation from this behavior is rather an exception (Ouchterlony,

2003). The details of our sieving process, with openings covered by beams of the machinery, could,

however, have distorted our results. We have tried to compensate for this by excluding the critical

data, but we do not know for certain that this has been entirely successful.

The relative flattening of our sieving curves may also be due to “selective” breakage in the mid-range,

which would increase the relative amount of fines. This resembles the behavior in autogenous

grinding, i.e. self-breakage of large fragments creates pebbles that then grind the mid-fractions finer,

and also an effect attributable to secondary fragmentation in block caving. In addition segregation

effects and thus preferential flow for certain fractions could explain the observations made.

The sublevel height is 28.5 m today. It was 9.0 m when Maripuu made his study in which altered

fragmentation characteristics were not observed. From the present large SLC layout one could expect

more comminution occurring in the debris flow, due to longer flow paths. On the other hand, the

present samples were taken before 10 % draw, which speaks in favour of relatively short paths, unless

the draw has been uneven like as for a progressively upwards developing shallow draw phenomenon.

ii


SAMMANFATTNING

Målet med denna studie var att ta reda på om Kiruna-magnetiten ur sprängteknisk synvinkel beter sig

som gråberg. Vår huvudslutsats är att den gör det.

För att ta reda på detta har vi siktat sprängd magnetit från 6 skopor som lastats i ort i Kiruna-gruvan

(krans nr 7, ort 377 i block 37 på 907-m nivån). Som jämförelsematerial har vi använt styckefallsdata

från sprängning, krossning och malning i labbskala samt från historiska data från gruvan. Skivhöjden

var då betydligt lägre än i dag.

Äldre siktdata för Kiruna-magnetiten (Maripuu, 1968) visar inga oregelbundenheter i

styckefallsfördelning och den är ur fragmenteringsteknisk synvinkel jämförbar med gråberg.

Medelstyckefallet x50 varierar stort men det finns ingen trend med utlastningsgraden.

Data i denna rapport visar att magnetiten i allt väsentligt har ett s.k. ”Natural Breakage

Characteristics”-beteende (NBC; Steiner, 1991 & 1998) i finområdet 0,063 - 10 mm. Minimilägenas

maskviddvärden x ≈ 0,25 mm i GGS-kurvorna överensstämmer med motsvarande värden hos

Maripuu`s data, trots den skilda kemiska sammansättningen. En petrografisk analys skulle kunna visa

om det finns samband mellan malnegenskaperna.

Medelstyckefallet från våra skopor varierar stort, inom 14,3 - 278 mm med ett totalmedelvärde om 86

mm, samma som hos Maripuu.

Våra siktkurvor följer inte helt ”Swebrec”-fördelningen (Ouchterlony, 2005), de är flackare över ett

mellanintervall om ca 25 - 75 mm. Detta är ovanligt då r2-värdet vid en passning annars till 95/100

ligger inom 0,995. En möjlighet är att själva siktningen påverkat resultaten då maskorna i vissa

siktdäck täcktes av tvärbalkar på undersidan. Sådana data har exkluderats i analysen men vi kan inte

utesluta att övriga data smittats.

Det flacka mellanpartiet i siktkurvan kan också vara ett resultat av selektiv sönderbrytning av

mellanfraktionerna, vilket ger förhållandevis mer finmaterial. Detta beteende liknar det som uppträder

vid autogenmalning, att stora spruckna fragment bryts sönder av egentyngden och så bildade malstenar

mal ner mellanfraktionerna. Denna typ av nermalning hänförs också till s.k. sekundär fragmentering i

blockras.

Skivhöjden i nuvarande brytning är 28,5 m mot 9,0 m när Maripuu gjorde sin studie, vars kurvor inte

visade någon autogenmalningseffekt. Man kan alltså förvänta mer nermalning i raset idag p.g.a. längre

flödesvägar för malmen. Å andra sidan togs våra skopor vid en lägre utlastningsgrad än 10 %, vilket

talar för relativt korta flödesvägar om inte flödet varit ojämnt som vid s.k. ”shallow draw” då

flödesvägen snabbt blir lång.

iii


CONTENTS

1 OBJECTIVE ............................................................................................................ 1

2 PREVIOUS FRAGMENTATION MEASUREMENTS ............................................... 2

3 EXPERIMENTAL CONDITIONS ............................................................................. 5

3.1 Test layout ............................................................................................................................... 5

3.2 Working procedure .................................................................................................................. 6

4 FRAGMENT SIZE DISTRIBUTIONS ...................................................................... 9

4.1 Sieving curves for 0 - 63 mm fraction samples ....................................................................... 9

4.2 Evaluation of complete sieving curves .................................................................................. 11

4.3 Analysis and discussion of results ......................................................................................... 14

5 ACKNOWLEDGEMENTS ......................................................................................17

6 REFERENCES .......................................................................................................18

7 APPENDICES ........................................................................................................21

iv


APPENDICES

Appendix 1. Procedure for estimating waste rock inflow. .................................................................... 21

Appendix 2. Fragment size distributions, Swebrec function fits, Maripuu (1968). .............................. 22

Appendix 3. Fragment size distributions, Rosin-Rammler fits, Lundberg (1961a-b). .......................... 23

Appendix 4. Raw data used within this report, Maripuu (1968). .......................................................... 24

Appendix 5. Raw data used within this report, Lundberg (1961a-b). ................................................... 24

Appendix 6. Drilling pattern, level 907, block 37, drift 3770, ring 7. ................................................... 25

Appendix 7. Charging pattern, level 907, block 37, drift 3770, ring 7. ................................................ 26

Appendix 8. Bucket images, buckets no. 1-6. ....................................................................................... 27

Appendix 9. Pile images (before mixing), piles no. 1-6. ....................................................................... 28

Appendix 10. Pile images (after mixing), piles no. 1-6. ........................................................................ 29

Appendix 11. Recording and physical measurement of boulders. ........................................................ 30

Appendix 12. Weighed fractions from lab-sieving and cumulative passing. ........................................ 31

Appendix 13. Data for calculation of continuous GGS exponents. ....................................................... 32

Appendix 14. Sieving curve: Maripuu (1968), caving debris coarse and fine (4 samples). .................. 35

FIGURES

Figure 1. Fragment size distribution for caving debris (5 blasts; > 10 mm: 41 samples and < 10 mm: 4

sam-ples) with Swebrec 3 parameter function fit. Data range 0.295 - 500 mm. Curve fit

parameters: x50 = 85.9 mm, xmax = 1110 mm, b = 2.931 with r2 = 0.99876. ....................... 3

Figure 2. Fragment size distribution for caving debris (5 blasts; > 10 mm: 41 samples and < 10 mm: 4

samples) with extended Swebrec function fit. Data range 0.074 - 500 mm. Curve fit

parameters: x50 = 86.1 mm, xmax = 1072 mm, b = 2.893, a = 0.999, c = 2.1 with r2 =

0.99879. .............................................................................................................................. 3

Figure 3. Parameter x50 versus extraction rate, Rosin-Rammler curve fit. .............................................. 4

Figure 4. Principles of sieving campaign. ............................................................................................... 6

Figure 5. Technical specifications and sieve deck configuration, Finlay 883. ........................................ 7

Figure 6. Layout of sieving campaign. .................................................................................................... 8

Figure 7. Sieving curves for 0 - 63 mm fraction samples ....................................................................... 9

Figure 8. Fragment size distribution for 0 - 63 mm fraction samples with basic Swebrec function fit.

Data range 0.125 - 40 mm. Parameters: x50 = 8.01 mm, xmax = 87 mm, b = 2.287 with r2 =

0.999. ................................................................................................................................ 10

Figure 9. Continuous GGS exponent curves for actual full-scale sieving and Maripuu`s data. ............ 11

Figure 10. Constructed complete sieving curve for sample 3, linear scales. ......................................... 13

Figure 11. Constructed complete sieving curve for sample 3, log-lin scales. ....................................... 13

Figure 12. Constructed, complete sieving curves for all samples, log-log scales. ................................ 14

v


Figure 13. Fragment size distributions for caving debris, Maripuu (1968). .......................................... 16

TABLES

Table 1. List of previous fragmentation measurements for blasted rock in Kiruna. ............................... 2

Table 2. Production data, block 37, drift 3770, level 907. ...................................................................... 5

Table 3. Weighed fractions and cumulative passing values for sieved samples. .................................... 8

Table 4. Swebrec function parameters for lab sample sieving data. ..................................................... 10

Table 5. XRF-analysis (actual data) and wet-chemical analysis of Fe- and P-%. ................................. 11

Table 6. Splicing procedure for construction of a complete sieving curve, sample 3. .......................... 12

1


1 OBJECTIVE

The objective of this investigation was to find out whether the Kiruna magnetite ore behaves like

waste rock from a blasting point of view. We studied the fragmentation characteristics for blasted

magnetite ore from the sublevel caving (SLC) operation at Kiruna (ring no. 7, drift 377 in block 37,

907 m level). The sieving results were also compared with fragmentation results from model-scale

blasts (Johansson et al., 2007). We also compared the results with the “Natural Breakage

Characteristics” (NBC) properties (Steiner, 1991 & 1998; Rohrmoser et al., 2007) which are discussed

in more detail elsewhere (Wimmer et al., 2008).

Photographs were taken of the extracted material in loader buckets and in test piles. These are

evaluated in a separate study using the image analysis program WipFrag. This evaluation then serves

as a calibration of the WipFrag system.

2


2 PREVIOUS FRAGMENTATION MEASUREMENTS

Table 1 lists previous fragmentation measurements carried out on blasted rock in Kiruna (Lundberg,

1961a-b; Maripuu, 1968). The present mining layout and operational conditions are quite different so a

direct comparison with these results is not appropriate.

Table 1. List of previous fragmentation measurements for blasted rock in Kiruna.

Characteristics Unit Lundberg Lundberg Maripuu Wimmer

Year - 1961a 1961b 1968 2008

Sieved material Caving debris Drifting Caving debrisβ Caving debris

γ

Mining

area

Level m 248 257 302 320 907

Coord. - Y26 - 27 Y27 - 28 Y24 Y35 - 36 Y37

Drift - - - 239-240 355-357 377, ring 7

Ore type - D D D D B

Sublevel interval m 9 9 9 9 28.5

Blasts - 5 5 6 5 1

Individual samples - 5 5 6 41 6

Extraction rate % begin / mid / end - 10 – 202 7.5 - 9.0

Total masses kg 180 323 44 000 197 683 96 454

Sieve sizes mm 10 - 500 10 -500 10 - 500 10 - 500 (41×)

0.063 - 200 0.074 - 10 (4×)

Burden / advance m 1.0-1.2 1.8 2.1 1.8 3

Hole diameter mm 33.5-36 51 32 51 115

Holes / round - 12 12 53 10 7

Drillmeters / round m 66 70 120 50.8 - 53.4 159.9

Tonnage / round t 361.4 - 395.6 591.3 180 534 - 550 6 591

Explosive type - Dynalit Dynalit/Anfo - Anfo Kimulux R&82

Specific charge kg / t 0.12 0.19α 0.33 0.15 - 0.17 0.23

α 0.22 kg/t (ANFO) β calculative break-down in ore and waste rock γ visually classified as pure ore without any contamination

An analysis of this historic data for Kiruna magnetite does not show any irregularities in the breakage

behavior. The magnetite ore has fragmentation characteristics which are comparable to those of waste

rock. Before Maripuu`s data were found, this could not be taken for granted. Previous blast damage

investigations had e.g. shown that the cracking behind half casts from perimeter blasting in drifts in

magnetite looked quite different than behind half casts in waste rock (Nyberg et al., 2000). In waste

rock the crack pattern is mainly radial, with many short crushing cracks at the borehole and a smaller

number of long distinct cracks. In ore the crack pattern is more diffuse, more like a spider`s web. Such

a web would probably occur if the magnetite showed plastic flow behavior. There were other

circumstances in Kiruna where the ore has been thought of as showing plastic deformation behavior

rather than brittle behavior.

Maripuu`s (1968) investigation of fragmented caving debris is the most extensive one because of the

large amount of samples studied at different extraction rates. For a few samples even information for

3


the fines range (0.074 - 10 mm) is available. Both the three and five parameter Swebrec function

(Ouchterlony, 2005) gives a good fitting to the data set; see Figure 1 and Figure 2.

Figure 1. Fragment size distribution for caving debris (5 blasts; > 10 mm: 41 samples and < 10 mm: 4 sam-ples) with Swebrec 3 parameter function fit. Data range 0.295 - 500 mm. Curve fit parameters: x50 =

85.9 mm, xmax = 1110 mm, b = 2.931 with r2 = 0.99876.

The parameter x50 has an average of 86 mm, but has a wide range, see Figure 3. No trend of x50 versus

extraction rate is directly noticeable.

Figure 2. Fragment size distribution for caving debris (5 blasts; > 10 mm: 41 samples and < 10 mm: 4 samples) with extended Swebrec function fit. Data range 0.074 - 500 mm. Curve fit parameters: x50 = 86.1

mm, xmax = 1072 mm, b = 2.893, a = 0.999, c = 2.1 with r2 = 0.99879.

0.1 1 10 100 1000

Mesh size, mm

1

10

Ma

ss p

assin

g, %

1

10

-2

1

-2

1

Re

sid

ua

ls [6

]

0.01 0.1 1 10 100 1000

Mesh size, mm

1

10

Ma

ss p

assin

g, %

1

10

-2

2

-2

2

Re

sid

ua

ls [6

]

4


Figure 3. Parameter x50 versus extraction rate, Rosin-Rammler curve fit.

Maripuu (1968) has also made an attempt to divide the caving debris masses into pure magnetite ore

and waste rock. An explanation of the procedure used is given in Appendix 1. It has been observed

that the fragment size distribution for waste rock is considerably coarser than that for ore with x50 =

161 mm and x50 = 79 mm, see Appendix 2. The percentage of fines for waste rock is much higher than

for ore, i.e. the fragment size distribution is much flatter.

The Rosin-Rammler curve fits Lundberg`s (1961a-b) data for both caving debris and drift material.

These curves are included in Appendix 3.

Appendix 4 and Appendix 5 contain relevant raw data from Maripuu (1968) and Lundberg (1961a-b)

which were used in this in this report.

0

25

50

75

100

125

150

175

200

225

250

275

300

325

350

375

400

0 25 50 75 100 125 150 175 200 225

Extraction rate, %

x5

0, m

m

blast 1

blast 2

blast 3

blast 4

blast 5

mean x50 = 86 mm

5


3 EXPERIMENTAL CONDITIONS

3.1 Test layout

A total of 6 buckets and 96 tonnes of magnetite ore were taken from ring no. 7, drift 377 within block

37, level 907 at the Kiruna mine. All buckets were loaded series after an initial extraction of 20

buckets, which corresponds to ~ 7.5 % of the total extraction. This ring was situated close to the

hanging wall. It was, therefore, not of full height and thus was not in accordance with the standard

layout of the SLC rings. An undisturbed previous extraction (Table 2) as well as operational

conditions led to the selection of this site for our tests.

Table 2. Production data, block 37, drift 3770, level 907.

Ring ID X-Coord. Date Orepass Theoretical mass

Loaded mass Ore Waste Sum

[-] [m] [-] [-] [t] [t] [t] [t] [%]

1 6510.5 26/05/2007 373 823 0 823 1707 207.4

2 6507.5 16/06/2007 374 2015 105 2120 901 42.5

3 6504.5 01/07/2007 373 2791 83 2874 486 16.9

4 6501.5 25/08/2007 374 3461 239 3700 4028 108.9

5 6498.5 05/09/2007 374 4357 133 4490 6750 150.3

6 6495.5 13/09/2007 374 4687 84 4771 4593 96.3

7 6492.5 21/09/2007 374 4462 0 4462 6591 147.7

8 6489.5 18/10/2007 374 4070 0 4070 2716 66.7

The local rock conditions were judged to be competent and undisturbed. The lower part of the ring

consisted of low phosphorus “B”-ore (Fe ~ 67 %, P ~ 0.01 %) and the upper part partly of high

phosphorus “D”-ore (Fe ~ 59 %, P > 0.3 %). The actual ring comprised 7 boreholes with a diameter of

115 mm, a forward inclination of 80° and a burden of 3 m to the next ring plane. A total of 159.9

drilled meters and a theoretical in-situ volume of 4462 m3 of ore give a figure for specific drilling of

0.17 m/m3. Drilling was carried out according to the drilling pattern shown in Appendix 6 by an

automated drill rig SIMBA W469. Water was present in some of the holes. Almost half of the charge

(47 %) therefore required a substitution of the standard bulk emulsion (Kimulux R) by the packaged

emulsion Kimulux 82. The actual specific charge thus amounted to 0.23 kg/t instead of the planned

0.35 kg/t. Apart from this the charge columns and initiation were implemented according to the

operating standard, see Appendix 7.

6


3.2 Working procedure

The test campaign is summarized by the following flow sheet, see Figure 4.

Figure 4. Principles of sieving campaign.

In order to ensure loading of pure magnetite the 6 individual samples have been taken before any

waste rock inflow after an initial extraction of 20 buckets, which corresponds to ~ 7.5 % of the total

extraction).

We had intended to calibrate the on-line fragmentation measurement system WipFrag (Carlsten, 2002;

Lith, 2003) owned by LKAB. Technical problems (communication with the system) prevented us

from using the built-in camera. For this reason, but also to later evaluate the influence of resolution

(640 x 480 – 3648 x 2736) on the image analysis algorithm, pictures were taken with a standard

remote controlled camera (Canon, Powershot G7). The camera was mounted close to the WipFrag

system under the roof. Appendix 8 summarizes the images taken of the 6 different buckets.

The material was then transported up to the surface and spread out on a plane tarmac surface close to

the processing plants. After flattening the piles, reference points were added and surveyed. From

pictures taken from a sky-lift, 3D models were reconstructed by means of photogrammetry. After re-

mixing the piles the same procedure was repeated. We plan to evaluate the pictures by some

granulometry analysis software (e.g. WipFrag), whereas the 3D data for the moment provide only a

detailed documentation of the piles. Images from the different piles before mixing are shown in

Appendix 9 and after mixing in Appendix 10.

7


The sieving campaign was accomplished with a mobile, track mounted, circular vibrating screen unit

(Finlay Hydrascreens, Finlay 883). We chose a moderate feed rate at the apron conveyor which feeds

the 2-deck screen-box. Figure 5 gives technical specifications for the screening unit as well as the

configuration of the individual sieving decks used.

Figure 5. Technical specifications and sieve deck configuration, Finlay 883.

The sieving procedure was carried out in the following three steps: 200/150, 100/63 and 35/12 mm.

For weighed fractions and calculated cumulative passing values, see Table 3.

The top deck had cross-beams which closed almost all available openings. Further, only one screen

segment was used for the 200 and 100 mm screens (see Figure 5). This led us to doubt the accuracy of

the corresponding values and they were excluded in our analysis. The amount as well as the size of

boulders was recorded, see Appendix 11. Laboratory samples were taken from the stream at the

conveyor belt from the masses < 63 mm and sieved down 0.063 mm by LKAB`s laboratory KSN

(Kvalitets Service Norra). The data is contained in Appendix 12.

8


Table 3. Weighed fractions and cumulative passing values for sieved samples.

Sample 1 2 3

Fraction (mm) kg % kg % kg %

> 200 6867.5 100.0 10535.6 100.0 5503.7 100.0

150-200 1137.5 58.1 505.6 33.9 593.7 70.2

100-150 2408.1 51.2 1836.2 30.7 3064.3 67.0

63-100 299.2 36.5 160.4 19.2 333.4 50.5

35-63 716.7 34.7 414.6 18.1 850.8 48.7

12-35 1306.7 30.3 771.6 15.5 2072.1 44.1

0-12 3656.7 22.3 1703.8 10.7 6073.5 32.8

Total 16392.4 - 15927.8 - 18491.5 -

Sample 4 5 6


> 200 5211.8 100.0 1799.9 100.0 3728.0 100.0

150-200 941.8 63.5 409.9 88.3 378.0 76.4

100-150 2952.4 56.9 2560.5 85.6 1768.6 74.0

63-100 169.0 36.2 233.8 68.9 373.8 62.8

35-63 655.0 35.1 695.1 67.3 763.2 60.4

12-35 1370.8 30.5 2065.1 62.8 1853.2 55.6

0-12 2982.4 20.9 7555.1 49.3 6923.2 43.9

Total 14283.2 - 15319.4 - 15788.0 -

The oversize, i.e. + 200 mm material, was manually put through a square 300 mm screen in order to

obtain a better resolution at the coarse end of the distribution. An important observation is that there

was much self breakage. Many of the oversize fragments that dropped from the belt split apart when

they hit the truck tray. The individual fractions from the full-scale test were weighed using a calibrated

scale (Mettler Toledo, Cougar/7800) at the industrial site of “Kiruna Grus och Sten” (KGS). It has a

20 kg accuracy. A cross-check with the scale used in the laboratory (Mettler Toledo, Spider SW) has

not shown any significant variance in the accuracy. Figure 6 shows the layout of the on-site sieving.

Figure 6. Layout of sieving campaign.

9


4 FRAGMENT SIZE DISTRIBUTIONS

4.1 Sieving curves for 0 - 63 mm fraction samples

Figure 7 shows the cumulative fragment size distributions for all 6 laboratory samples from 0 - 63

mm. A pronounced self-similarity can be observed since the curves are parallel shifted upward in the

log-log diagram, at least up to 10 mm. This is to be expected when fine material follows the NBC

concept. Sample 1 is an exception. Inadequacies in the sampling method may explain the deviant

curve for sample 1.

Figure 7. Sieving curves for 0 - 63 mm fraction samples

A curve fitting to the averaged laboratory sample data using the 3 parameter Swebrec function, see

Figure 8, gives a near perfect fit with r2 value of 0.999 over a large interval from 0.125 - 40 mm.

Furthermore the residuals are stochastically distributed.

To adjust the fit in the fines region a weighting of the squared residuals by 1/√(x) has been made.

The Swebrec function parameters for all laboratory sieving data are contained in Table 4.

1

10

100

0.01 0.1 1 10 100

Mesh size [mm]

Mass

pa

ssin

g [

%]

Sample 1

Sample 2

Sample 3

Sample 4

Sample 5

Sample 6

Average

10


Figure 8. Fragment size distribution for 0 - 63 mm fraction samples with basic Swebrec function fit. Data range 0.125 - 40 mm. Parameters: x50 = 8.01 mm, xmax = 87 mm, b = 2.287 with r

2 = 0.999.

Table 4. Swebrec function parameters for lab sample sieving data.

Sample x50 xmax b range r

2 s50 s50 • x50

0.75

mm mm - mm - 1/mm 1/mm0.25

1 11.23 64 2.317 0.25-40 0.997 0.030 0.182

2 9.94 82 2.338 0.25-40 0.999 0.028 0.156

3 6.80 176 2.767 0.25-40 0.999 0.031 0.132

4 8.80 75 2.188 0.25-40 0.999 0.029 0.148

5 4.19 209 3.042 0.25-25 0.999 0.046 0.136

6 5.40 55 2.003 0.25-40 0.997 0.040 0.142

Figure 9 shows the continuous GGS exponent plots derived from the extended Swebrec function for

both the actual sieving data and Maripuu`s data (1968). Relevant data as well as the calculation are

contained in Appendix 13.

All curves coincide with each other, which supports the hypothesis that the sieving curves from the lab

samples are of a NBC character (Ouchterlony & Moser, 2006).

Furthermore, the minima for the actual as well as the old data clearly occur around x ~ 0.25 mm. The

position of the minimum seems to be directly related to the petrographic character of the investigated

ore (Grasedieck, 2006). The minimum lies where the majority of grains change from polymineralic

assemblies to monomineralic pieces.

The described characteristic is not associated with the chemical composition since the investigated

magnetite ore types (B as well as D type) are disparate, see Table 5 and Maripuu (1968). Thus the

chemical composition does not seem to have altered the assembly of grains. A petrographic study of

the different ore types would shed more light on this matter.

0.1 1 10 100

Mesh size, mm

1

10

Ma

ss p

assin

g, %

1

10

-0.5

1.5

-0.5

1.5

Re

sid

ua

ls [9

]

11


Figure 9. Continuous GGS exponent curves for actual full-scale sieving and Maripuu`s data.

Table 5. XRF-analysis (actual data) and wet-chemical analysis of Fe- and P-%.

Actual dataα, fraction (mm) -0.063 0.125/0.063 0.250/0.125

Fe-% 62.55 66.29 65.63

P-% 0.35 0.24 0.12

Maripuuβ, fraction (mm) -0.074 0.147/0.074 0.295/0.147

Fe-% 45.00 50.15 50.90

P-% 2.33 2.36 1.92 α mean of 6 samples; β mean of 4 samples

4.2 Evaluation of complete sieving curves

The construction of the complete sieving curves was accomplished in the following way (Ouchterlony

et al., 2006):

1. From the measurements taken from the boulders (Appendix 11) a theoretical, imaginary

grizzly size can be computed (i.e. largest dimension from the largest block). Since a grizzly

with a given gap can be passed by larger fragments than a square mesh with the same

dimensions a flakiness factor has to account for that circumstance. The flakiness value was

found out to be 1.10. The same flakiness factor was considered for the rectangular built screen

openings 12 x 30 mm which gave an effective mesh size of 13.2 mm.

2. The screening at 200, 150 and 100 mm involved hexagonal punch plates whereas the

corresponding quadratic mesh size can be obtained by a comparison of the available opening

(decreased area by a factor of √(3)/2).

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.01 0.1 1 10 100 1000

Mesh size, mm

GG

S e

xp

on

ent,

-

Sample 1

Sample 2

Sample 3

Sample 4

Sample 5

Sample 6

Average

Maripuu: caving debris

12


3. Practical circumstances (explanation in chapter 3.2) finally impeded the use of the data points

at 200 and 100 mm.

4. Since the Swebrec function is relatively linear within the range of 10 - 60 % passing and the

cumulative sieving data for 63, 35 and 12 mm mesh sizes lie well within this range, absent

data points in the full-scale test can be taken from a straight line interpolation.

5. As 13.2 mm is missing in the lab screen series, the 13.2 mm data point has been interpolated

from the 12.5 and 16 mm data points.

6. The linear curve behavior within the range of 10 - 60 % mass passing rendered a splicing at

13.2 mm possible by scaling the laboratory sample data for all smaller screen sizes. This

makes the laboratory sample a relatively smooth continuation of the interpolation line into the

fines region.

Table 6 as well as Figure 10 to Figure 11 clarify the procedure of splicing for the construction of a

complete fragmentation distribution on the basis of sample 3.

All constructed fragmentation curves are shown in Figure 12.

Table 6. Splicing procedure for construction of a complete sieving curve, sample 3.

Data type Mesh

size

Mesh

size* Lab sample Mass Full-scale Splice Final curve

- mm mm Passing % Fraction kg Passing % 13.2mm Passing %

xmax 390 429 6097.4 100.00 100.00

Finlay, hex 150 129.9 3397.7 67.03 67.03

Finlay, quadratic 63 63 100.00 850.8 48.65 52.10 48.65

Lab sample 40 40 91.11 44.87 47.47 44.87

Finlay, quadratic 35 35 87.90 2072.1 44.05 45.80 44.05

Lab sample 30 30 85.84 41.61 44.73 41.61

Lab sample 25 25 82.14 39.18 42.80 39.18

Lab sample 20 20 74.07 36.74 38.59 36.74

Lab sample 16 16 66.91 34.79 34.86 34.79

Finlay, 12x30mm 12 13.2 63.03 6073.5 32.84 32.84 32.84

Lab sample 12.5 12.5 62.06 32.33 32.33

Lab sample 10 10 58.85 30.66 30.66

Lab sample 8 8 53.83 28.05 28.05

Lab sample 6.3 6.3 48.40 25.22 25.22

Lab sample 5 5 44.94 23.41 23.41

Lab sample 4 4 41.12 21.43 21.43

Lab sample 2 2 29.56 15.40 15.40

Lab sample 1 1 21.07 10.98 10.98

Lab sample 0.5 0.5 16.02 8.35 8.35

Lab sample 0.25 0.25 12.70 6.62 6.62

Lab sample 0.125 0.125 9.56 4.98 4.98

Lab sample 0.063 0.063 5.76 3.00 3.00

Note: * mesh size converted; italic values are interpolated

13


Figure 10. Constructed complete sieving curve for sample 3, linear scales.

Figure 11. Constructed complete sieving curve for sample 3, log-lin scales.

0

10

20

30

40

50

60

70

80

90

100

0 50 100 150 200 250 300 350 400 450 500

Mesh size [mm]

Mass

pa

ssin

g [

%]

Full-scale sieving

Grizzly (imaginary)

200/100 mm, hex corrected (excluded)

Full-scale sieving: flakiness + hex corrected

Lab sample 0-63 mm

Interpolated data

0

10

20

30

40

50

60

70

80

90

100

0.01 0.10 1.00 10.00 100.00 1000.00

Mesh size [mm]

Mass

pa

ssin

g [

%]

Full-scale sieving

Grizzly (imaginary)

200/100 mm, hex corrected (excluded)

Full-scale sieving: flakiness + hex corrected

Lab sample 0-63 mm

Interpolated data

14


Figure 12. Constructed, complete sieving curves for all samples, log-log scales.

4.3 Analysis and discussion of results

The differences between the particle size distributions for six buckets loaded in succession are

substantial. The parameter x50 varies between 14.3 mm (sample 5) and 277.6 mm (sample 2). This

agrees with our first visual impressions.

Similar large variations in the fragment size distribution for blasted magnetite ore were observed by

Maripuu (1968) and are also common for the raw material delivered by the primary crusher to the

processing plant (Hahne et al., 2003).

On average x50 amounts to 86.5 mm, however, and this is directly comparable to the mean x50 value

that Maripuu (1968) measured in earlier tests, see chapter 2.

The shapes of the complete sieving curves do not entirely fit the Swebrec function though. An

increased amount of fines < 40 mm causes a flattening and thus a non-uniform continuation of the

curve to coarser fractions.

The curves are superficially similar to those obtained by blasting near the critical burden, i.e. a limited

number of large fragments plus a fines tail that follows the Swebrec distribution (Ouchterlony, 2008).

The specific charge in the SLC ring was substantially lower than normal, see chapter 3.1, which would

support this similarity. However, a rapid, disturbance-free extraction for the ring investigated which

would support this similarity runs counter to this supposition.

0.1

1

10

100

0.01 0.1 1 10 100 1000

Mesh size [mm]

Ma

ss p

ass

ing

[%

]

Sample 1

Sample 2

Sample 3

Sample 4

Sample 5

Sample 6

Average

15


The flattening effect observed for the mid-sizes could also be due to “selective” breakage behavior and

is comparable to the shape of fragment size distributions typically affected by autogenous grinding

(Lynch, 1977; Hahne et al., 2003). According to a testing and modeling approach recently carried out

(Lichter, 2007) a significant fraction of the Kiruna magnetite has the unusual tendency to break very

quickly within a batch mill and to generate a large fraction of very fine material.

Similar effects may occur within a blasted SLC ring. Because of the low specific charge within the

blasted ring (see chapter 3.1) more coarse fragments than usual would result.

Besides the ore properties such coarse material constitutes an ideal feed for a self-grinding action.

Drawing of the ore and internal flow mechanisms might have caused self-breakage and abrasion

effects. This might cause a depletion of medium size fractions, yet leave strong, large fragments.

We observed self-breakage during the sieving process. Results from drop weight- and abrasion tests

(Hahne et al., 2003) also indicate that such effects occur in the mill feed that comes from the crusher.

The resistance of feed samples both to impact- and abrasion breakage increases as the distance of

sampling from the mining face increases. Larsson (1998) refers to autogenous grinding effects mainly

occurring within the caving debris.

From an autogenous grinding point of view, the coarse fragmented material of low specific charge and

the ore properties provide a perfect starting point for grinding action.

An autogenous grinding hypothesis might be verified in the following ways:

The shape and surface properties of fine particles could tell if the material has been exerted to

autogenous grinding (Forssberg & Zhai, 1985). It was shown that autogenous grinding

processes typically produce rounded particles with high degrees of liberation and

equiaxiality, and lower roughness.

Evaluation of such effects by full-scale observations and measurements, e.g. comparison with

ore pass conditions (sieving before and after an ore pass).

Summarized, several different mechanisms are conceivable to account for an altered fragmentation

mechanism:

Self-breakage depending on shape and strength of particles

Abrasion effects between particles (autogenous grinding)

Crushing of fragments under superimposed load

Fracturing & failure of larger blocks under different forms of load

16


In addition segregation effects and thus preferential flow for certain fractions could explain the

observations made.

Another explanation for the flat part of the sieving curve could be geological structures with a typical

spacing of 50 - 100 mm. However, the magnetite does not seem to contain such structures.

The previous investigation by Maripuu (1968) is of interest. 4 out of 41 samples down to < 10 mm, see

Figure 13, are of special interest.

Figure 13. Fragment size distributions for caving debris, Maripuu (1968).

One of the curves from the caving debris shows a similar, distinctive non-uniform distribution (Blast

III/4). This is roughly comparable to the present findings, but over a lower range of fragmented sizes.

This discrepancy is in Maripuu`s investigation associated with a high amount of waste rock inflow (21

%). Two reasons are likely to account for this observation: a) a blending of ore and waste with

different fragmentation properties and b) that the highly resistant surrounding waste rock possesses

ideal autogenous grinding properties for the ore. However, if the mean data points are taken, a curve

fitting using the basic Swebrec function gives a perfect fit again with r2 value of 0.9993 (interval 0.147

- 200 mm) and the following parameters: b = 2.84, xmax/x50 = 7.65 and xmax = 765, see Appendix 14.

Another difference is that the scale of the mining layout has changed tremendously during the years,

see Table 1 (chapter 2). The scale of today works in favour of a larger fragment size. Thus if any

autogenous grinding is present within the flow this would today have a greater effect. Further, the

length of the flow path has increased considerably because of the larger scale involved and a possible

0.1

1

10

100

0.01 0.1 1 10 100 1000

Mesh size, mm

Ma

ss p

ass

ing

, %

Blast II/4, 48 % extr., 1 % waste

Blast III/4, 84 % extr., 21 % waste

Blast IV/3, 39 % extr., 5 % waste

Blast V/4, 51 % extr., 19 % waste

Average

17


shallow, progressively upwards developing draw phenomenon (Power, 2004; Selldén & Pierce, 2004).

Thus the possible exposure time of material to any kind of grinding action can be assumed to be

extended too.

On the other hand, as our buckets were loaded early in the drawing sequence this would indicate that

there was a relatively short flow path. Thus there is no convincing explanation of the observed

flattening of the fragment size distributions in Figure 12.

Despite this flattening deviation from Swebrec distribution behavior, our main conclusion is still that

the magnetite qualitatively behaves like waste rock from a blasting point of view.

5 ACKNOWLEDGEMENTS

Hjalmar Lundbohm Reserch Centre (HLRC) is thanked for supporting the project “Improved breakage

and flow in sublevel caving”, and financial support of this sieving campaign. LKAB is also thanked

for the support of this project and the practical support on-site.

18


6 REFERENCES

Carlsten, J. (2002). Fragmenteringsmätning med bildanalys [Fragmentation measurement with image

analysis] (Unpublished report 03-746). Kiruna, Sweden: LKAB.

Forssberg, E. & Zhai H. (1985). Shape and surface properties of the particles liberated by autogenous

grinding. Scandinavian Journal of Metallurgy, 14(1), 25-32.

Grasedieck, A. (2006). Die Natürliche Bruchcharakteristik (NBC) von Gesteinen in der Sprengtechnik

[Natural breakage characteristics (NBC) applied for rock blasting] (Doctoral thesis). University of

Leoben, Leoben, Austria.

Hahne, R., Pålsson, B.I. & Samskog, P.O. (2003). Ore characterisation for-and simulation of-primary

autogenous grinding. Minerals Engineering, 16(1), 13-19.

Johansson, D., Ouchterlony, F. & Nyberg, U. (2007). Blasting against aggregate confinement,

fragmentation and swelling in model scale. In P. Moser (Ed.), 4th World Conference on Explosives and

Blasting (pp. 13-26). England: EFEE, European Federation of Explosives Engineers.

Larsson, L. (1998). Slutrapport “Projekt Skivras 2000” [Final report ”project sublevel caving 2000”]

(Unpublished report 98-765). Kiruna, Sweden: LKAB.

Lichter, J. (2007). Review of feed size distribution and mill operating parameters on the performance

of the KA2 comminution circuit (Unpublished report LK01M). York, USA: Metso Minerals Industries

Inc., Metso Minerals Optimization Services.

Lith, A. (2003). Study on the usage of WipFrag to describe blasted ore fragmentation in sublevel

caving operations at the Kiruna mine (Unpublished internal report). Kiruna, Sweden: LKAB.

Lundberg, S. (1961a). Tappning, transport och krossning av skivrasberg på 320 m avv. i KUJ.

Delutredning: Siktanalys av skivrasberg [Drawing, transportation and crushing of caving material at

level 320 m in the Kiruna underground mine. Interim report: fragment size distribution of material

from caving] (Unpublished report 116-1071a). Kiruna, Sweden: LKAB.

Lundberg, S. (1961b). Tappning, transport och krossning av skivrasberg på 320 m avv. i KUJ.

Delutredning: Siktanalys av ortberg [Drawing, transportation and crushing of caving material at level

320 m in the Kiruna underground mine. Interim report: fragment size distribution of material from

drifting] (Unpublished report 116-1071b). Kiruna, Sweden: LKAB.

Lynch, A.J. (1977). Mineral crushing and grinding circuits – their simulation, optimisation, design

and control (vol. 1). Amsterdam, Netherlands: Elsevier Scientific Publishing Company.

19


Maripuu, R. (1968). Undersökning av siktanalys och styckeform från skivrasbrytningen vid LKAB,

Kiruna [Investigation of fragment size and shape from sublevel caving at LKAB, Kiruna] (Master

thesis). Royal Institute of Technology, Stockholm, Sweden.

Nyberg, U., Fjellborg, S., Olsson, M. & Ouchterlony, F. (2000). Bedömning av sprängskador i

ortkontur; Vibrationsmätningar, skadeprognoser och sprickkartering i magnetitmalm och gråberg

[Vibration measurements, damage predictionsn and crack mapping in magnetite ore and waste rock]

(SveBeFo Rapport 50). Stockholm, Sweden: Svensk Bergteknisk Forskning.

Ouchterlony, F. (2003). Influence of blasting on the size distribution and properties of muckpile

fragments, a state-of-the-art review. (Report MinFo project P2000-10: Energy optimization during

comminution. Stockholm, Sweden: Swebrec, Swedish Blasting Research Centre at Luleå University of

Technology.

Ouchterlony, F. (2005). The Swebrec function: linking fragmentation by blasting and crushing.

Transactions of the Institute of Mining and Metallurgy, Section A: Mining Technology, 114, A29-A44.

Ouchterlony, F. (2008). Personal communication.

Ouchterlony, F. & Moser, P. (2006). Likenesses and differences in the fragmentation of full-scale and

model-scale blasts. 8th International Symposium on Rock Fragmentation by Blasting (pp. 207-220).

Santiago, Chile: Instituto de Ingenieros de Chile.

Ouchterlony, F., Olsson, M., Nyberg, U., Andersson, P. & Gustavsson, L. (2006). Constructing the

fragment size distribution of a bench blasting round, using the new Swebrec function. 8th International

Symposium on Rock Fragmentation by Blasting (pp. 332-344). Santiago, Chile: Instituto de Ingenieros

de Chile.

Power, G. (2004). Full scale SLC draw trials at Ridgeway Gold Mine. In A. Karzulovic & M.A.

Alafaro (Eds.), 4th International Conference and Exhibition on Mass Mining (pp. 225-230). Santiago,

Chile: Instituto de Ingenieros de Chile.

Rohrmoser, S., Hollerer, H. & Comoli, C. (2007). Magnetite ore samples from LKAB´s operation in

Kiruna/Sweden. Optimized comminution sequence, natural breakage characteristic, energy register

function (Unpublished report). Leoben, Austria: Institute of Mineral Processing, University of Leoben.

Selldén, H. & Pierce, M. (2004). PFC3D modeling of flow behaviour in sublevel caving. In A.

Karzulovic & M.A. Alafaro (Eds.), 4th International Conference and Exhibition on Mass Mining (pp.

201-214). Santiago: Instituto de Ingenieros de Chile.

20


Steiner, H.J. (1991). The significance of the Rittinger equation in present-day comminution

technology. In H. Schubert (Ed.), 17th International Mineral processing Congress (vol. 1, pp. 177-

188). Freiberg, Germany: Polygraphischer Bereich Bergakademie Freiberg.

Steiner, H.J. (1998). Zerkleinerungstechnische Eigenschaften von Gesteinen [Comminution technical

properties of rocks]. Felsbau, 16(5), 320-325.

Wimmer, M., Ouchterlony, F. & Moser, P. (2008). The fragment size distribution of Kiruna magnetite,

from model-scale to run of the mine. In H. Schunnesson & E. Nordlund (Eds.), 5th International

Conference and Exhibition on Mass Mining (pp. 691-703). Luleå, Sweden: Luleå University of

Technology.

21


7 APPENDICES

Appendix 1. Procedure for estimating waste rock inflow.

Fractions ≥ 150mm: hand sorting of ore – waste (hand-magnet)

Fractions < 150mm: wet chemical analysis (Fe- % and P- %)

m-value:

i.e. conversion of apatite to a corresponding iron ore content

m-value = Fe-% + 3.927 • P-%

Waste (hanging wall, quartz porphyr): m = 3 (no phosphor but 3 % Fe)

In-situ ore (apatite ore): m, %

Caving debris mass: M, %

Correlation:

M = X * 3 + (1 – X) * m

X = (m – M) / (m - 3)

X as waste in weight % within extracted caving debris

≥ 150mm:

▪ Ore and waste fractions determined directly by hand sorting (hand-magnet)

< 150mm:

▪ Fe- % and P- % (i.e. m-values) for pure iron-ore determined for each blast and sample in the

fraction 150 - 200 mm by wet chemical analysis (200 - 300 kg sample, crushed < 10 mm), averaged

within a blast and set as constant for the respective blast (used in calculation of X)

▪ Fe- % and P- % (i.e. M-values) determined for each fraction < 150 mm by wet chemical

analysis of the caving debris (200 - 300kg sample, crushed < 10 mm)

▪ Calculation of X, waste in weight %

22


Appendix 2. Fragment size distributions, Swebrec function fits, Maripuu (1968).

23


Appendix 3. Fragment size distributions, Rosin-Rammler fits, Lundberg (1961a-b).

24


Appendix 4. Raw data used within this report, Maripuu (1968).

Maripuu, 1968: level 320m, Y35-36, drift 355-357

Blast no. 1 2 3 4 5

Samples 8 8 12 8 5

Total mass (kg) 40 643 36961 56565 38602 24912

Fraction (mm) % % % % %

> 500 17.6 100.0 2.6 100.1 5.8 99.9 2.8 100.0 7.7 100.0

200-500 15.2 82.4 14.1 97.5 12.5 94.1 18.0 97.2 13.3 92.3

150-200 9.9 67.2 14.7 83.4 13.5 81.6 10.3 79.2 7.8 79.0

50-150 23.1 57.3 39.3 68.7 31.5 68.1 29.3 68.9 25.0 71.2

20-50 13.5 34.2 16.0 29.4 15.8 36.6 15.0 39.6 16.5 46.2

10-20 7.3 20.7 5.0 13.4 7.8 20.8 8.2 24.6 9.8 29.7

< 10 13.4 13.4 8.4 8.4 13.0 13.0 16.4 16.4 19.9 19.9

Blast no. 2 3 4 5

Sample no. 4 4 3 4

Fraction (mm) % % % %

4.7-10 - 47.49 100.00 22.41 100.00 33.47 100.00 22.12 100.00

2.36-4.7 - 19.88 52.51 14.26 77.59 20.15 66.53 19.48 77.88

1.17-2.36 - 10.13 32.63 10.87 63.33 11.4 46.38 13.21 58.40

0.59-1.17 - 5.87 22.50 8.46 52.46 7.36 34.98 8.82 45.19

0.295-0.59 - 3.87 16.63 7.79 44.00 5.6 27.62 6.87 36.37

0.147-0.295 - 3.63 12.76 10.15 36.21 6.42 22.02 8.33 29.50

0.074-0.147 - 3.32 9.13 10.23 26.06 5.94 15.60 8.35 21.17

0-0.074 - 5.81 5.81 15.83 15.83 9.66 9.66 12.82 12.82

Appendix 5. Raw data used within this report, Lundberg (1961a-b).

Lundberg, 1961a: level 248m, Y26-27, drift -

Blast 1 2 3 4 5


> 500 6.3 100.0 0.0 100.0 5.2 95.0 0.0 100.0 3.5 96.4

130-500 20.0 93.8 28.3 71.8 22.7 72.3 22.6 77.5 25.4 71.0

50-130 21.8 73.8 23.6 48.2 17.8 54.5 21.3 56.2 22.3 48.7

20-50 14.2 52.0 15.2 33.0 11.9 42.6 15.0 41.2 14.2 34.5

10-20 11.5 37.8 11.0 22.0 9.7 32.9 10.4 30.8 9.5 25.0

0-10 26.3 26.3 22.0 0.0 32.9 0.0 30.8 0.0 25.0 0.0

Lundberg, 1961a: level 257m, Y27-28, drift -

Blast 1 2 3 4 5


> 500 21.0 100.0 11.2 100.0 18.8 100.0 2.2 100.0 15.7 100.0

130-500 34.1 79.0 36.1 88.8 31.8 81.2 24.7 97.8 36.0 84.3

50-130 17.2 44.9 26.0 52.7 23.1 49.4 33.3 73.1 20.5 48.3

20-50 7.4 27.7 10.3 26.7 9.5 26.3 17.6 39.8 10.1 27.8

10-20 6.5 20.3 6.1 16.4 6.5 16.8 8.6 22.2 7.6 17.7

0-10 13.8 13.8 10.3 10.3 10.3 10.3 13.6 13.6 10.1 10.1

Lundberg, 1961b: level 302m, Y24, drift 239-240

Blast 1 2 3 4 5 6

Fraction (mm) % % % % % %

> 500 3.9 100.0 0.0 100.0 0.0 100.0 0.0 100.0 0.0 100.0 0.0 100.0

130-500 13.9 96.1 7.2 100.0 12.1 100.0 11.8 100.0 12.3 100.0 11.7 100.0

50-130 24.3 82.2 18.8 92.8 19.2 88.0 22.0 88.1 17.3 87.7 18.9 88.4

20-50 22.0 57.9 21.3 74.0 16.0 68.8 22.0 66.1 18.5 70.4 22.1 69.5

10-20 16.2 35.9 18.8 52.7 16.0 52.8 13.2 44.1 18.5 51.9 15.8 47.4

0-10 19.7 19.7 33.9 33.9 36.8 36.8 30.9 30.9 33.4 33.4 31.6 31.6

25


Appendix 6. Drilling pattern, level 907, block 37, drift 3770, ring 7.

26


Appendix 7. Charging pattern, level 907, block 37, drift 3770, ring 7.

27


Appendix 8. Bucket images, buckets no. 1 - 6.

28


Appendix 9. Pile images (before mixing), piles no. 1 - 6.

29


Appendix 10. Pile images (after mixing), piles no. 1 - 6.

30


Appendix 11. Recording and physical measurement of boulders.

Sample 1 2 3

Size (mm) x y z x y z x y z

1 960 860 520 1200 1100 600 700 480 280

2 780 580 300 940 830 400 700 400 390

3 450 380 420 1000 650 250 750 500 200

4 450 400 380 840 480 350 - - -

5 450 340 260 700 550 350 - - -

6 400 330 230 760 430 320 - - -

Grizzly-value 520 600 390

Flakiness-factor (1.1) 572 660 429

Sample 4 5 6

Size (mm) x y z x y z x y z

1 680 470 300 480 380 260 1100 870 500

2 550 480 170 370 340 190 600 480 450

3 - - - 440 300 260 - - -

4 - - - - - - - - -

5 - - - - - - - - -

6 - - - - - - - - -

Grizzly-value 300 260 500

Flakiness-factor (1.1) 330 286 550

31


Appendix 12. Weighed fractions from lab-sieving and cumulative passing.

Sample 1 2 3


40-63 1.040 100.00 0.435 100.00 0.540 100.00

35-40 0.150 91.39 0.375 93.05 0.195 91.11

30-35 0.460 90.14 0.060 87.06 0.125 87.90

25-30 0.435 86.33 0.310 86.10 0.225 85.84

20-25 1.112 82.73 0.520 81.15 0.490 82.14

16-20 1.177 73.52 0.565 72.84 0.435 74.07

12.5-16 1.057 63.77 0.585 63.82 0.295 66.91

10-12.5 0.752 55.01 0.280 54.47 0.195 62.06

8-10 1.060 48.78 0.360 50.00 0.305 58.85

6.3-8 1.010 40.00 0.365 44.25 0.330 53.83

5-6.3 0.522 31.64 0.255 38.42 0.210 48.40

4-5 0.485 27.31 0.183 34.35 0.232 44.94

2-4 0.871 23.29 0.600 31.42 0.702 41.12

1-2 0.520 16.08 0.439 21.83 0.516 29.56

0.5-1 0.299 11.77 0.240 14.81 0.306 21.07

0.25-0.5 0.221 9.30 0.153 10.98 0.202 16.02

0.125-0.25 0.220 7.47 0.135 8.54 0.191 12.70

0.063-0.125 0.267 5.65 0.154 6.39 0.230 9.56

0-0.063 0.416 3.44 0.246 3.93 0.350 5.76

Total 12.072 - 6.260 - 6.075 -

Sample 4 5 6


40-63 0.250 100.00 0.470 100.00 0.000 100.00

35-40 0.155 95.37 0.320 93.17 0.165 100.00

30-35 0.340 92.50 0.115 88.53 0.105 97.59

25-30 0.305 86.20 0.000 86.86 0.300 96.06

20-25 0.440 80.56 0.235 86.86 0.450 91.68

16-20 0.345 72.41 0.525 83.44 0.705 85.11

12.5-16 0.415 66.02 0.315 75.82 0.475 74.82

10-12.5 0.215 58.33 0.195 71.24 0.295 67.88

8-10 0.325 54.35 0.305 68.41 0.365 63.58

6.3-8 0.350 48.33 0.390 63.98 0.355 58.25

5-6.3 0.200 41.85 0.270 58.32 0.225 53.07

4-5 0.182 38.15 0.290 54.39 0.210 49.78

2-4 0.568 34.78 0.852 50.19 0.820 46.71

1-2 0.390 24.26 0.749 37.82 0.692 34.74

0.5-1 0.211 17.04 0.436 26.94 0.397 24.64

0.25-0.5 0.136 13.14 0.289 20.60 0.262 18.85

0.125-0.25 0.130 10.63 0.274 16.40 0.247 15.03

0.063-0.125 0.168 8.22 0.335 12.42 0.300 11.42

0-0.063 0.276 5.12 0.520 7.56 0.482 7.04

Total 5.400 - 6.885 - 6.850 -

32


Appendix 13. Data for calculation of continuous GGS exponents.

Mesh size Geometric Average 1-6

midpoint Passing GGS GGS P'(x) P(x)

mm mm % discrete continuous %/mm %

63 100.00

40 50.2 93.53 0.15 0.14 0.27 97.23

35 37.4 89.98 0.29 0.24 0.58 91.99

30 32.4 86.84 0.23 0.28 0.77 88.62

25 27.4 82.84 0.26 0.33 1.01 84.19

20 22.4 75.73 0.40 0.37 1.31 78.40

16 17.9 67.07 0.54 0.41 1.66 71.77

12.5 14.1 60.02 0.45 0.44 2.04 64.86

10 11.2 55.92 0.32 0.46 2.42 58.28

8 8.9 49.81 0.52 0.47 2.78 52.48

6.3 7.1 43.85 0.53 0.48 3.16 47.01

5 5.6 40.19 0.38 0.48 3.56 42.02

4 4.5 36.83 0.39 0.47 3.97 37.74

2 2.8 26.70 0.46 0.45 4.89 30.54

1 1.4 18.90 0.50 0.42 6.70 22.57

0.5 0.7 14.44 0.39 0.39 9.44 17.04

0.25 0.35 11.50 0.33 0.38 14.16 13.05

0.125 0.177 8.73 0.40 0.43 24.18 9.89

0.063 0.089 5.35 0.72 0.62 48.60 6.96

5 parameter Swebrec function fit

xmax/x50 - 9.58

x50 mm 8.08

xmax mm 77.38

b - 2.15

a - 0.999732

c - 2

Mesh size Geometric Sample 1



63 100.00

40 50.2 91.39 0.20

35 37.4 90.14 0.10 0.07 0.19 99.75

30 32.4 86.33 0.28 0.22 0.66 97.67

25 27.4 82.73 0.23 0.37 1.24 92.95

20 22.4 73.52 0.53 0.51 1.93 85.00

16 17.9 63.77 0.64 0.61 2.57 74.92

12.5 14.1 55.01 0.60 0.68 3.07 64.33

10 11.2 48.78 0.54 0.70 3.43 54.70

8 8.9 40.00 0.89 0.70 3.66 46.77

6.3 7.1 31.64 0.98 0.69 3.85 39.84

5 5.6 27.31 0.64 0.66 4.01 34.00

4 4.5 23.29 0.71 0.64 4.17 29.34

2 2.8 16.08 0.53 0.58 4.55 22.22

1 1.4 11.77 0.45 0.50 5.41 15.30

0.5 0.7 9.30 0.34 0.44 6.86 11.06

0.25 0.35 7.47 0.32 0.40 9.28 8.29

0.125 0.177 5.65 0.40 0.38 13.76 6.35

0.063 0.089 3.44 0.72 0.44 23.83 4.81


xmax/x50 - 4.07

x50 mm 9.84

xmax mm 40.00

b - 1.97

a - 0.999924

c - 2

33





63 100.00

40 50.2 93.05 0.16 0.15 0.29 97.11

35 37.4 87.06 0.50 0.27 0.66 91.24

30 32.4 86.10 0.07 0.33 0.88 87.38

25 27.4 81.15 0.32 0.39 1.16 82.28

20 22.4 72.84 0.48 0.44 1.50 75.63

16 17.9 63.82 0.59 0.49 1.88 68.10

12.5 14.1 54.47 0.64 0.53 2.25 60.39

10 11.2 50.00 0.38 0.55 2.60 53.22

8 8.9 44.25 0.55 0.56 2.92 47.05

6.3 7.1 38.42 0.59 0.56 3.24 41.38

5 5.6 34.35 0.48 0.55 3.56 36.34

4 4.5 31.42 0.40 0.54 3.87 32.12

2 2.8 21.83 0.53 0.51 4.57 25.24

1 1.4 14.81 0.56 0.47 5.94 17.97

0.5 0.7 10.98 0.43 0.43 8.01 13.18

0.25 0.35 8.54 0.36 0.41 11.56 9.85

0.125 0.177 6.39 0.42 0.46 18.88 7.32

0.063 0.089 3.93 0.71 0.63 36.17 5.09


xmax/x50 - 7.76

x50 mm 9.98

xmax mm 77.45

b - 2.26

a - 0.999778

c - 2




63 100.00

40 50.2 91.11 0.20 0.15 0.28 94.26

35 37.4 87.90 0.27 0.21 0.50 89.42

30 32.4 85.84 0.15 0.24 0.64 86.58

25 27.4 82.14 0.24 0.27 0.82 82.93

20 22.4 74.07 0.46 0.31 1.08 78.19

16 17.9 66.91 0.46 0.34 1.39 72.72

12.5 14.1 62.06 0.31 0.37 1.76 66.85

10 11.2 58.85 0.24 0.40 2.16 61.08

8 8.9 53.83 0.40 0.41 2.57 55.81

6.3 7.1 48.40 0.45 0.42 3.02 50.67

5 5.6 44.94 0.32 0.43 3.52 45.83

4 4.5 41.12 0.40 0.43 4.03 41.54

2 2.8 29.56 0.48 0.43 5.20 34.06

1 1.4 21.07 0.49 0.42 7.47 25.37

0.5 0.7 16.02 0.39 0.40 10.81 19.13

0.25 0.35 12.70 0.34 0.40 16.40 14.52

0.125 0.177 9.56 0.41 0.45 27.77 10.87

0.063 0.089 5.76 0.74 0.64 54.24 7.55


xmax/x50 - 19.26

x50 mm 6.88

xmax mm 132.50

b - 2.51

a - 0.999617

c - 2

34





63 100.00

40 50.2 95.37 0.10 0.13 0.26 97.80

35 37.4 92.50 0.23 0.25 0.62 92.37

30 32.4 86.20 0.46 0.30 0.83 88.74

25 27.4 80.56 0.37 0.36 1.09 83.93

20 22.4 72.41 0.48 0.41 1.42 77.65

16 17.9 66.02 0.41 0.45 1.78 70.52

12.5 14.1 58.33 0.50 0.48 2.15 63.17

10 11.2 54.35 0.32 0.50 2.52 56.27

8 8.9 48.33 0.53 0.51 2.85 50.28

6.3 7.1 41.85 0.60 0.51 3.19 44.72

5 5.6 38.15 0.40 0.50 3.55 39.71

4 4.5 34.78 0.41 0.49 3.91 35.47

2 2.8 24.26 0.52 0.47 4.72 28.44

1 1.4 17.04 0.51 0.43 6.33 20.82

0.5 0.7 13.14 0.37 0.40 8.76 15.65

0.25 0.35 10.63 0.31 0.38 12.90 11.98

0.125 0.177 8.22 0.37 0.42 21.44 9.13

0.063 0.089 5.12 0.69 0.57 42.37 6.56


xmax/x50 - 8.01

x50 mm 8.85

xmax mm 70.84

b - 2.11

a - 0.999806

c - 2




63 100.00

40 50.2 93.17 0.16 0.04 0.07 99.39

35 37.4 88.53 0.38 0.08 0.22 97.65

30 32.4 86.86 0.12 0.11 0.33 96.30

25 27.4 86.86 0.00 0.14 0.48 94.29

20 22.4 83.44 0.18 0.18 0.73 91.29

16 17.9 75.82 0.43 0.22 1.07 87.32

12.5 14.1 71.24 0.25 0.26 1.52 82.52

10 11.2 68.41 0.18 0.30 2.05 77.29

8 8.9 63.98 0.30 0.33 2.63 72.10

6.3 7.1 58.32 0.39 0.35 3.30 66.66

5 5.6 54.39 0.30 0.37 4.06 61.23

4 4.5 50.19 0.36 0.39 4.85 56.17

2 2.8 37.82 0.41 0.40 6.69 46.84

1 1.4 26.94 0.49 0.41 10.18 35.32

0.5 0.7 20.60 0.39 0.40 15.10 26.70

0.25 0.35 16.40 0.33 0.40 22.91 20.26

0.125 0.177 12.42 0.40 0.44 37.95 15.20

0.063 0.089 7.56 0.73 0.60 72.22 10.72


xmax/x50 - 22.54

x50 mm 3.33

xmax mm 75.01

b - 2.48

a - 0.999001

c - 2

35





63 100.00

40 50.2 100.00 0.00

35 37.4 97.59 0.18 0.13 0.34 98.21

30 32.4 96.06 0.10 0.19 0.55 95.99

25 27.4 91.68 0.26 0.25 0.83 92.54

20 22.4 85.11 0.33 0.30 1.19 87.51

16 17.9 74.82 0.58 0.35 1.60 81.31

12.5 14.1 67.88 0.39 0.39 2.05 74.50

10 11.2 63.58 0.29 0.41 2.51 67.78

8 8.9 58.25 0.39 0.43 2.94 61.71

6.3 7.1 53.07 0.39 0.43 3.40 55.88

5 5.6 49.78 0.28 0.43 3.89 50.47

4 4.5 46.71 0.28 0.43 4.39 45.77

2 2.8 34.74 0.43 0.41 5.52 37.73

1 1.4 24.64 0.50 0.38 7.76 28.61

0.5 0.7 18.85 0.39 0.36 11.23 22.14

0.25 0.35 15.03 0.33 0.36 17.44 17.31

0.125 0.177 11.42 0.40 0.42 31.45 13.32

0.063 0.089 7.04 0.71 0.63 67.03 9.39


xmax/x50 - 8.83

x50 mm 5.49

xmax mm 48.51

b - 1.88

a - 0.999532

c - 2

Appendix 14. Sieving curve: Maripuu (1968), caving debris coarse and fine (4 samples).

Report 2007:1 ISSN 1653-5006

Swedish Blasting Research CentreMejerivägen 1, SE-117 43 Stockholm

Luleå University of TechnologySE-971 87 Luleå www.ltu.se

An experimental investigation of blastability

Experimentell bestämning av sprängbarhet

Matthias Wimmer, Swebrec

Universitetstryckeriet, L

uleå

The fragment size distribution of Kiruna magnetite loaded...

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