12.10.2013
Fragmentation Distribution Study of
Rock Blasting in Erdenet Open Pit Mine
1
Outline
Introducing Erdenet open pit mine and mining process
Blasting
Fragmentation measurement method
Fragmentation prediction method
Applying new design standard
Summary
2
Introduction 3
Open Pit Mine Process
Drilling
Blasting
Loading
Transportation
Crushing
Grinding
Processing Introduction
4
Blasting
One of the most important unit of open pit operation
Purpose:
To fracture solid ores and rocks, prepare the material for
excavation and transport
Blasting influences in loading, hauling and primary crushing.
Improvement of blasting results provides increase in loader
and excavator productivity due to increased diggability
capacity and increased bucket and truck fill factors.
Blasting 5
Blasting
Suitable and uniform particle size distribution results
increase in crusher and mill throughput and decrease in
energy consumption in size reduction process.
Now what is the optimum fragment size?
How can we improve blasting design ?
Blasting 6
Blasting 7
Blasting 8
Fragmentation Measurement Method
The size distribution analysis of the rock fragmentation
1. Sieving method (direct)
2. Digital Image processing method (indirect )
The size distribution analysis of the rock fragmentation by
sieving is a direct and accurate method but it is very time
consuming and costly.
Fragmentation analysis by digital image processing is a low cost
and quick method.
Fragmentation measurement method 9
Split-Desktop System
Split system is one of the digital image processing software
developed to compute the size distribution of fragmented
rock from digital images.
From muckpile,
haul truck,
waste dump,
stockpile,
conveyor belt, or any other location
Fragmentation measurement method 10
Once the images are taken and saved to a computer, the
Split-Desktop software has five progressive steps for
analyzing each image
Step 1. The scaling
Step 2. The automatic delineation of the fragments
Step 3. The editing of the delineated fragments
Step 4. The calculation of the size distribution based on the
delineated fragments.
Step 5. To display the size distribution results.
Split-Desktop System
Fragmentation measurement method 11
The scaling
Fragmentation measurement method
65022 12
The Delineation
Fragmentation measurement method
65022 13
The scaling
Fragmentation measurement method
80101 14
The Delineation
Fragmentation measurement method 80101
15
The scaling
Fragmentation measurement method
80102 16
The Delineation
Fragmentation measurement method
80102 17
The scaling
Fragmentation measurement method
95175 18
The Delineation
Fragmentation measurement method
95175 19
The scaling
Fragmentation measurement method
69025 20
The Delineation
Fragmentation measurement method
69025 21
Fragmentation measurement method 22
The Results of Combined Size Distribution
Fragmentation measurement method 23
Fragmentation Prediction Method
(Kuz-Ram Model)
A common model in industry for predicting rock fragmentation size distribution by blasting
- Kuznetsov formula
median fragment size, cm
A rock factor
Qe mass of explosive being used, kg
SANFO weight strength of the explosive to ANFO
k powder factor, kg/m3
Fragmentation prediction method 24
=
(2)1/
=
(Rosin-Rammler formula)
x Screen size
n Uniformity index
- Characteristic size (63.2% passing size) R porportion of material retained on the screen
= 2.2 14
1 +
2(1
)(
)
Kuz-Ram Model
Fragmentation prediction method 25
Pattern Design Amount Unit
Hole Diameter, de 250 mm
Charge Length, l 8.5 m
Burden, B 8 m
Spacing, S 8 m
Subdrilling, J 2 m
Drill Accuracy, W 0.1 m
Bench Height, L 15 m
Powder Factor, k 0.39 kg/m3
Charge Weight per Hole, Qe 355 kg/hole
Youngs Modulus, E 200 GPa
UCS 117 MPa
Specific Gravity of Rock 2.6
Specific Gravity of Explosive 0.85
Velocity of Detonation 4400 m/s
Blasting Parameters of Erdenet Open Pit Mine
Fragmentation prediction method 26
Results of Kuz-Ram Model Amount Unit
Rock Factor, A 4
Median Size of Material, 25 cm
Uniformity Index, n 1.04
Characteristic Size, x 0.35 m
Max Boulder Size, (R=0.02) 1.318 m
Predicted Fragmentation Percent
Percent Oversize, >400mm 32%
Percent In Range, 0-400mm 68%
Predicted Results From Kuz-Ram Model,
(EMC blasting parameters)
Fragmentation prediction method 27
Comparison Between Image Processing and Kuz-Ram Model
Fragmentation prediction method 28
The Ash Design Standard
One of the classic papers in rock blasting The mechanics of
rock blasting was written by Ash. K (1963).
The value of the K ratios for each parameters such as burden,
spacing, subdrilling and stemming were calculated from the
data collected at the different rock types hole depths, hole
diameters and all grades of explosives.
Ash design standard 29
Using K ratio, determined optimum parameters that provide
improvement for size of fragment distribution.
Ash design standard 30
Pattern Design Amount Unit
Hole Diameter, de 250 mm
Charge Length, L 11.5 m
Burden, B 7.5 m
Spacing, S 10 m
Subdrilling, J 2 m
Drill Accuracy, W 0.1 m
Bench Height, H 15 m
Powder Factor, k 0.47 kg/m3
Charge Weight per Hole, Qe 490 kg/hole
New Blasting Parameter
Ash design standard 31
Results of Kuz-Ram Model Amount Unit
Rock Factor, A 4
Median Size of Material, 22 cm
Uniformity Index, n 1.43
Characteristic Size, x 0.29 m
Max Boulder Size, (R=0.02) 0.751 m
Predicted Fragmentation Percent
Percent Oversize, >400mm 20.5%
Percent In Range, 0-400mm 79.5%
Predicted Results of New Design
Kuz-Ram Model
Ash design standard 32
Comparison Between New and Current Blasting Design
Applied to Kuz- Ram Model
Ash design standard 33
Summary
Fragmentation size distribution was measured with image
processing method and was predicted by Kuz-Ram model on the EMC blasting data
Blasting design was improved by Ash design standard
Passing percent of fragmentation was increased from 68 % to 80% compare with two different blast design in Kuz-Ram model.
Explosive consumption increased 38 %,
Image processing method was limited accuracy because only using one part of muckpile image.
Using I-Site 3D Laser Scanner we can more accurately measure fragmentation distribution
Using High Speed camera we can analyze motion of blasted rock and we can improve design
34
35