minimizing quarrying costs

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inpit+blasting_baumaschinentech_2006.ppt/Jarmo Eloranta

Minimizing Quarrying Costs by Inpit Crushingand correct Shotrock Fragmentation

Jarmo Eloranta, Dr.Sc.(Tech)Vice President, ResearchMetso Minerals Crushing & Screening

3.Fachtagung Baumaschinentechnik 2006Oct. 5-6. 2006

Dresden, Germany



2


© Metso Minerals, Inc.

Contents

• General

- Starting point

- Quarry Process

- Approach to study

• Comparison of different shotrock fragmentation

- Impact of different elements in drilling and blasting

• Comparison of different crushing methods

- Comparison of stationary, semimobile and mobile concepts

• Summary of quarry development

- Process Integration and Optimization (PIO)

- Potentials



3



Basic assumptions:

• There is a minimum of thetotal product cost for a givenfragmentation curve

• Crushing methods impact tothe total quarry costs

Starting Point



4



Quarry Process

Quarry Process includes:

• Drilling &Blasting

• Secondary breaking

• Loading

• Hauling

• Crushing

Quarry Process can be:

• Stationary

• Semi mobile

• Fully mobile



5



Quarry Process

Typical distance 2km



6



Crushing

Drilling

Blasting

LoadingHauling

Example of Quarry Cost distribution



7



Challenge in Quarry Development

Distance

$/ton

What about the

hauling distance?

Source: Technical University, Trondheim, Norway



8



Approach done in two phases

1 Comparison of different shotrockfragmentations, including:

- drilling and blasting

- boulder handling

- loading

- hauling

- crushing (traditional stationary)

2 Comparison of different crushing methods,including:

- stationary

- ‘inpit’, semimobile

- in-pit, fully mobile

Optimumdrilling &blasting

Optimumcrushing

Cost

Effective

QuarryPractise




Comparison of different shotrockfragmentation



10



Starting point: stationary three stage plant with capacity 1600t/h.Final product 0-20mm

MAIN DATA Case 1 Case 2 Case 3 Case 4 Case 5

Drillig:Nr.of unitsDrilling pattern (m2)

39

46,4

55,8

64,5

83,3

Blasting:Specific charge (kg/m3)K50 (mm), L

0,53410

0,7629 0

0,925 0

1,15200

1,56150

Number of operators 18-22Loading by excavatorsBucket size (m3)Nr.of units

122-7 depending on blast configuration (or bigger buckets)

Hauling by trucks:

Pay-load (t)Distance (km)Nr.of units

502

8-10 depen ding on blast configurationCrushing:Primary crusher typeNr.of primary unitsNr.of sec.&tertary units

Nordberg C160 jaw25

GeneralDrillability & blasta bilityWork index (kWh/t)Drill hole dia (mm )Bench height (m)

ExplosiveInterest rate (%) / Quarry life (y)Fuel price ($/liter) / Energy ($/kWh)Wages ($/hour)

45 / 0,7158910

An fo10 / 20

0,5 / 0,117

All together more than 50 different cases were analysed

Comparison of different shotrock fragmentations



11



Impact of drillhole diameter to drilling and blasting costsK5 0 = 250, drillability = me dium , blastability = good

0 ,0 0

0 ,1 0

0 ,2 0

0 ,3 0

0 ,4 0

0 ,5 0

0 ,6 0

0 ,7 0

0 ,8 00 ,9 0

1 ,0 0

1 ,1 0

1 ,2 0

1 ,3 0

1 ,4 0

1 ,5 0

6 4 8 9 1 1 5

Drillhole diamete r [m m ]

T o t a l c o s t s [

U S D / t ]

0 ,0 0

0 ,1 0

0 ,2 0

0 ,3 0

0 ,4 0

0 ,5 0

C o s t s [

U S

D / t ]

Blasting

Drilling

Blasting

Drilling


Source: Metso Minerals & Tamrock studies



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Impact of Drilling Hole Diameter

H o l e D i a m e t e r (m m )

D r i l l & B l a s t ( U S D

/ t o n )

B la s t i n g

D r i l l i n g

C o s t 1 . p r e / A .

L i s l e r u d

H o l e D i a m e t e r

(m m )

Q u a n t i t y p e r t o n

B o u l d e r

c o u n t

% F i n e s i n

s h o t r o c k

M i c r o - c r a c k d a m a g e o f

f r a g m e n t s

F r a g m e n t

e l o n g a t i o n

r a t i o





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Boulder handling

• boulder count dependent on primary

crusher opening

• sort boulders from muck pile

• down size the boulders

• minimize boulder count using tighter drill

patterns or reduced uncharged height





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Example of costs caused by boulders.

Customer case, breakage before loadingHammering Costs ($/tonnes)

0

10

20

3040

50

60

0 0,05 0,1 0,15 0,2 0,25 0,3

$/tonnes

n u m b e r o f b o u

l d e r s / h





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050

100

150

200

250300

R e l a t i v e c o s t

410 290 250 200 150

K50 value

Impact of Blast Distribution to Loading Costs


Source: Technical University, Trondheim, Norway%100

80

60

40

20

0

K50

50%

K50 definition



16



9092

94

96

98

100

102

104

106

R

e l a t i v e c o s t

410 290 250 200 150

K50 value

Impact of Blast Distribution to Hauling Costs with Dumbers


Source: Technical University, Trondheim, Norway%100

80

60

40

20

0

K50

50%

K50 definition



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Why coarser blast distribution impacts to loading and hauling costs?

• Material is more difficult to load due to:

- more likely toe problems

- bigger boulders

• Scope of equipment is changed due to more difficult and/or longer cycle times

• In the equipment there is

- more wear

- more maintenance




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Case 1 Case 2 Case 3 Case 4 Case 5

0

1

2

3

4

C o s t s [ U S D / p r o d u c e

d t o n ]

Hauling

Loading

Hammering

Crushing

Blasting

Drilling

Total costs / produced ton

Results

Case K50

(mm)

Case 1 410

Case 2 290

Case 3 250

Case 4 200

Case 5 150

K50 is 50%point of fractiondistribution




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Conclusions of shotrock fragmentation

• There is an optimum shotrock fragmentation from the total product cost pointof view. In the case study optimum was k50 ~ 250 mm.

• Crushing cost share is almost unchanged with different K50 values becauseblast impacts only to primary crushing

• Even smaller drillhole diameters than used here (89mm) can be economical,because:

- Smaller drillhole diameter produces less fines. In many cases this considered to be awaste

- There are less boulders to be handled

- There are less micro cracks in the blasted rock due to more ‘gentle blasting’. In manycases this brings better final aggregate quality

• Boulder management is important





Comparison of different crushing methods



21



Starting points for crushing method comparisons


• k50=250mm is being used as a shotrock fragmentation

• Following quarrying methods are being compared:- stationary:

• material transported by dump trucks into the crushing plants

- ‘inpit’, semimobile

• material transported by dump trucks into the semimobile primary jaw crusher, andfrom there by conveyors to the secondary & tertiary crushing plants

- in-pit, fully mobile

• primary crushing done in quarry face with highly mobile track mounted jawcrusher, and from there by conveyors into the secondary & tertiary crushingplants. No dump trucks



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Stationary CrushersPrimary crusher cannot normally be moved

Typical distance 2km




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Semimobile in-pit crushingPrimary crusher can be moved but only on non frequent basis




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In-pit fully mobile crushingPrimary crusher is track mounted, compact andmovable within 5-10 minutes




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In-pit fully mobile crushingMovable and steerable Lokolink conveyor system is a key component




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Starting point: three different plant configurations with capacity 1600t/h. Final product 0-20mm

Stationary plant Semimobile primary

plant

Fully mobile in-pit

primary plantPrimary crusher typeSizeNumber of units

Fixed JawC160

2

Semimobile JawC140

2

Track mounted JawC125

2Loaders, excavators:Bucket size (m3)Number of units

122

5,53

5,52

Dump trucks:Size (t)Number of unitsHaulage distance(km)

5082

3571

---

Conveyor length (km) - 1 4Number of operators 20 20 11Secondary & tertiary

crushers andscreens *)

Secondaries: 2 * Nordberg OC 1560

Tertiaries: 3 * Nordberg HP500Seven Screens: 10-20m2Other variables As in previous drilling & blasting example

*) = K10 in Hong-Kong




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Results

Difference between stationary and fully mobile is about 25%

Stationary Semimobile Fully mobile0

0,5

1

1,5

2

2,5

3

3,5

C o s t s [ U S D

/ p r o d u c e d t o n ]

Hauling

Loading

Hammering

Crushing

Blasting

Drilling

Total costs / produced tonK50 = 250mm, Feed rate 1600t/h





Summary



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Process integration and optimisation (PIO)

Characterise quarry domains

(strength and structure)

Benchmarking, modelling andsimulation

Potential impact on wall damage

and control

Implement blast design in the field

Measure fragmentation

Evaluate effect of blast designon fragmentation

Implement crushing strategies

and systems

Quantify the effect of

fragmentation on circuit performance

O p t i m

i s e d ( b l a s t

i n g + c r u

s h i n g

+ s c r e e

n i n g ) = M a x

( € € € )



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Potentials for quarry development

Main messages:

• Whole quarry processoptimisation instead of sub-optimisation of individualcomponents via Process

Integration and Optimisation(PIO)

• Inpit crushing can giveremarkable benefits



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minimizing quarrying costs

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