GEOMINING GUIDE
FOR
CEMENT QUAARY MANAGER
3.7 Designing Surface Blasting Rounds
.
Table of Contents
1. Health
, Safety and Environment
2. Geology
3. Surface
4. Mobile
Drilling and Blasting
Equipment
5. Crushing
and Screening
6. Raw
Mix
7. Mine
Planning
8. Outsourcing
and Contractor Management
9. Performance
10.Cost
Management
Management
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Table of Contents
3.
Surface Drilling and Blasting
1.
Surveying Work in Drilling & Blasting Work
2.
Surface Drilling
3.
Industrial Explosives
4.
Priming Initiation and Blasting Accessories
5.
Rock Breakage Mechanisms
6.
Blasting Geology
7.
Designing Surface Blasting Rounds
8.
Rock Fragmentation
9.
Environmental Effects of Quarry Blasting
10.
Quarry Blast Diagnosis
11.
Blast Optimization
12.
Specialized Blasting Techniques
13.
Misfire Handling
14.
Planning of Drilling and Blasting Work
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Designing Surface Blasting Rounds
Rock
Geometry
Explosives
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Factors Affecting Blasting Operation
Rock Properties
Hardness
Young
modulus
Compressive strength
Tensile strength
Porosity
Vibration, Air blast, Fly rock,
Rock Fragmentation and
Cut according blast design
Blast Design Properties







Hole diameter
Bench height
Burden
Spacing
Stemming length & material
Sub-drilling
Drill pattern
Explosive Properties






Types (ANFO, emulsion, gel,
dynamite etc.)
Velocity of detonation
Density,
Water resistance
Quantity,
Delay
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Optimum Explosives Performance
Optimum Explosive Performance May be achieved :

Explosive energy distribution in the rock-mass :
 Energy must be evenly distributed to achieve uniform fragmentation

Explosive energy confinement
 Explosive energy must be confined long enough after detonation to
establish fractures and to displace material
 Use the proper stemming length and stem material type

Explosive energy level
 Energy level must be sufficient to overcome
the structural strength and mass of the rock
and while providing controlled displacement
 Determine energy level on the degree of
fragmentation and displacement required
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Geometrical Parameters of Bench Blast

Hole Diameter

Burden

Spacing

Bench Height

Angle Of Inclination
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Hole Diameter
Factors Controlling Hole Diameter Selection:








Safety
Environmental effect (vibration, air-blast ,fly-rock and dust)
Degree of fragmentation
Equipment used
Bench height
Geological formation
The selection of the blast-hole diameter is a key factor in efficient
blasting.
A rule of thumb is the maximum suggested blast-hole diameter (mm) for
a known bench height should be equal to the bench height (m)
multiplied by 15.
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Hole Diameter & Bench Height




The selection of the blast-hole diameter is a key factor in efficient
blasting.
The maximum hole diameter should be H/60 .
Smaller holes distribute the explosive energy better than larger holes.
Greater hole diameters lead to improper energy distribution.
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Hole Diameter & Bench Height
_ Large hole diameter and low bench energy
yield are difficult to control.
_ Bad blast effect
_ Small hole diameter and high bench energy
yield are reduced.
_ Drill and blast cost is high
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Hole Diameter & Burden
What is the burden with 102 mm hole diameter?
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Burden Formulas
Burden values 127mm hole diameter
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Hole Diameter & Burden
Optimum Burden is in the range of 20 to 40 times the hole
diameter, depending on the rock breakage.
Øc = Hole diameter
V > 60 Øc
V = 60 Øc
V = 40 Øc
V = 20 Øc
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Pattern Types

equilateral pattern
gives most even
distribution

S:B ratio = 1.15
- good for very hard
rock

energy fall 
distance2
@ square centre
23% less
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Basic Blast Design

Typical burden dimensions in the mining and quarrying industries are:

average ~ 32 hole diameters in average density rocks (<3.3 g/cc)
26 hole diameters for high density rocks (3.3 g/cc).
Burden stiffness ratio (Bench Height / Burden):



If ratio <2 , rock-mass will be stiff, harder to fracture and require
more subdril.

Low stiffness ratios require relatively higher energy factors to
produce uniform fragmentation.
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Basic Blast Design
Poor Energy Distribution
Bench Height
Hole Diameter
Burden
Stifness Ratio
Stemming
Vertical Energy Dist.
: 10m
: 311mm
: 10m
:1
: 7m
: 30 %
Bench Height
Hole Diameter
Burden
Stifness Ratio
Stemming
Vertical Energy Dist.
: 10m
: 145mm
: 5m
:2
: 3.5m
: 65 %
Bench Height
Hole Diameter
Burden
Stifness Ratio
Stemming
Vertical Energy Dist.
: 10m
: 92mm
: 3.3m
:3
: 2.3m
: 77 %
Fair Energy Distribution
Good Energy Distribution
The stiffness ratio can be improved by using smaller hole diameter or greater
bench height and Vertical Energy Distribution > 80% for uniform fragmentation
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Burden & Spacing

excessive burden

reduced fragmentation, displacement
small burden

rock / face burst, airblast
excessive spacing

reduced fragmentation, toe / face problems
small spacing




inter-hole crushing, cratering, blocks, toe
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Burden & Spacing
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Basic Blast Design

Spacing: normally ranges from 1 to 1.8 times the burden

Optimum energy distribution

spacing = 1.15 x burden
pattern = staggered configuration.
Subdrilling:



= burden (m) x 0.3

OR
= charge diameter (mm) x 0.0085
Stemming Material: crushed stone 4-11mm for Ø<102mm



8-20mm for Ø>102mm
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Basic Blast Design


Stemming:

= burden (m) x 0.7

OR

= charge diameter (mm) x 0.022
ALSO

Stemming should be based on the Relative Confinement (RC) of
the explosive charge, not only percentage of the burden dimension
RC =
(Stem Length x 210 000) + (Charge Diameter x 600)
(Charge Energy ABS X Charge Diameter)

Charge Energy ABS (Absolute Bulk Strength) for ANFO is
3,145j/cc

RC should be greater than 1.4 to prevent excessive loss of
confinement and flyrock
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Hole Inclination
Hole inclination, generally 5 to 25 (10 to 15  most common)


Disadvantages of inclined holes:

Increased alignment errors
More difficult to achieve drilling accuracy

Closer supervision required, expert driller


Shorter bit life and high drilling cost/m
Advantages of inclined holes:

better energy distribution
reduced back break and toe problems,

Improved muckpile shape and position,


Stable bench edge.
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Blast Design

Select shape and layout of blast to
avoid adverse edge effects, fly-rock
and air-blast enabling efficient blasting
and optimum explosive performance

Length to depth ratio to minimize
back break, stemming ejection and air
blast
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Blast Shape
Select a shape
The broken rock needs 30-40 % extra volume for swell
Avoid 90° corners
Utilize free faces




A: Not bad. Some damage to corners.
B: Very good shape utilizing to free faces
C: Damage to corners. stemming ejection and air-blast
D: Damage to corners. High probability for stemming ejection and air blast
E: Box-cut = damage, air-blast and fly-rock
A
B
C
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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E
24
Explosive Energy Effect





Hole angle
Number of free faces
Sub drill
Diameter of the hole
Stiffness of the bench
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Stiffness Ratio
The stiffness of the bench is the bench height divided by the
burden
S 
h
V
h : Bench height [m]
V: Burden [m]
Stiffness ratio
1
2
3
4
Fragmentation
Bad
Medium
Good
Excellent
Air-blast
Bad
Medium
Good
Excellent
Fly-rock
Bad
Medium
Good
Excellent
Vibrations
Bad
Medium
Good
Excellent
Comments
BAD DESIGN
New
design if
possible
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
Increasing the
stiffness-ratio
above 4 does not
always give a
positive effect
26
Timing

Purposes of sequential detonation are to :

Control the application of explosive energy during the detonation of
the blast


Control explosive energy confinement

Maintain maximum explosive energy input
Delay:

between holes in a row should be in the range of 3 – 10 ms/m of
Spacing

between holes rows should be in the range of 10 – 30 ms/m of
Burden
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Timing and Muck Pile Profile
materials thrown back onto bench
excessive backbreak especially
with high benches
tight
some overbreak with high benches
tight, compact
little overbreak
loose, spread out
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
Insufficient
interval between
rows
( less than 6
ms/m of burden )
Short delay
interval
between rows
( 6 to 12 ms/m
of burden )
suitable
for shovel
excavation
Long delay
interval between
rows
( 12 to 30 ms/m
of burden )
suitable
for loader
excavation or
blast casting
28
Delay Between Rows
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Delay Between Rows
The proper delay between rows depends on:
42 ms
No of rows
67 ms
Equipment
Previous blast mucked out
Charge concentration
Rock proporties
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Straight Firing Pattern
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Straight Firing Pattern (Nonel)
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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V Shape 1 Firing Pattern
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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V Shape 1 Firing Pattern (Nonel)
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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V Shape 2 Firing Pattern
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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V Shape 2 Firing Pattern (Nonel)
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Firing Pattern (Nonel)
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Comparing Firing Pattern
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Directed Firing Pattern (Nonel)
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Directed Firing Pattern
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Blasting Software
Task
Software
Features
1.
Hole layout
Mine design system
Survey, Geology
2.
Charging
MDS, in-house
Geology
3.
Timing
Compu-Blast
ShotPlan
Vib. analysis
Plans, simulation
4.
Specialist
ProWall, ProBlast
Costing
5.
General
PBS
JKSimBlast
Very basic
Comprehensive
6.
Other
WinProf
Flexit
Face profile
Hole deviation
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Group Exercise
Suggest a loading pattern for the example below
Parameters:
Crest
Face height 15.0 metres
Hole inclination = 80°
Stemming
Hole diameter = 110mm
B
(4.0 metres)
Blast hole depth = 16.5 metres
Burden (B) = 4.0 metres
Spacing (S) = 4.0 metres
Sub-grade (U) = 1.3 metres
Hole
Quarry Face
(15m)
ANFO Column Charge
ANFO (9kg/metre)
(12.5 metres)
Cast Pentolite primer
(112.5 kgs)
Nonel Unidet 500
Toe
Pentolite Primer
Explosives available:
U
Quarry Floor
(454 g)
with 1 x U500 Detonators
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Group Exercise
Suggest a loading pattern for the example below
Parameters:
Crest
Stemming
Face height 12.0 metres
Hole inclination = 75°
Hole diameter = 105mm
B
(3.2 metres)
Blast hole depth = 13.4 metres
Burden (B) = 3.2 metres
Spacing (S) = 3.2 metres
Sub-grade (U) = 1.0 metres
ANFO Column Charge
(7.2 metres)
Hole
Quarry Face
(15m)
Explosives available:
ANFO (9kg/metre)
(64.8 kgs)
Slurry (12kg/metre)
Emulsion (11kg/metre)
Cast Pentolite primer
Slurry Cartridges
Nonel Unidet 500
with 1 x U500 Detonator
Water level
Toe
U
Quarry Floor
(1.0 metre)
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Group Exercise
Suggest a loading pattern for the example below
What are the issues ?
A
Reduced crest burden (A)
Crest
Back-break causing reduced burden (B)
“Fly-rock risk”
Quarry
Face
B
Toe
Quarry Floor
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Group Exercise
Suggest a loading pattern for the example below
What are the issues ?
A
Reduced crest burden (A)
Crest
Bach-break causing reduced burden (B)
Increased Stemming
“Fly-rock risk”
(4.5 metres)
Upper Column
(explosives)
Deck (intermediate
stemming)
Quarry
Face
Deck = length of problem area plus 0.3 x
Burden (above and below)
B
(4.0 metres)
Lower Column
(explosives)
Toe
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
Quarry Floor
45
Group Exercise
Suggest a loading pattern for the example below
What is the issue ?
Crest
Reduced toe burden (C)
“Fly-rock risk”
Quarry
Face
C
Toe
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
Quarry Floor
46
Group Exercise
Suggest a loading pattern for the example below
What is the issue ?
Crest
Reduced toe burden (C)
“Fly-rock risk”
Stemming
(4.0 metres)
Quarry
Face
Confinement at toe must be increased to
eliminate fly-rock
Explosives Column
(with Primers and
Detonators)
C
Toe
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
Quarry Floor
47
Effects Due To Bad Design

Loading






Hauling



bad truck filling
bunching due to boulder selection
Crushing



low bucket fill factor
boulder selection
lower diggability
bad under-footing of loading area
higher maintenance cost for loading equipment
higher kWh/t
higher maintenance cost for crusher
Secondary breakage

more work and more cost
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Problem Solving

Toes and irregular floor
 Increase subdrilling
 Reduce drilling pattern
 Increase bottom charge
 Increase delay times between rows

Boulders
 Reduce drilling pattern
 Use higher strength explosive
 Increase charge in the hole
 Redistribute the charge in the hole
 Adjust delay times between holes

Fines
 Increase drilling pattern
 Use low strength explosive
 Decrease charge in the hole
 Redistribute the charge in the hole
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Problems Solving (Continued)

Fly rock
 Control burden in front row
 Control voides or cavities in the holes
 Control hole deviation
 Adjust delay times between holes
 Adjust stemming length and material size

Vibration
 Reduce charge weight per hole or delay
 Reduce number of holes with the same delay
 Adjust delay time and firing sequence
 Control geometric design of blast
 Make face with large free area

Air blast
 Adjust stemming length and material type
 Use electrical initiation and decrease use of detonating cord
 Cover detonating cord when it is used
 Decrease charge hole
 Adjust delay times between holes
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Problems Solving (Continued)

Reduced displacement and swelling
 Increase powder factor
 Reduce burden in first row
 Adjust delay time and firing sequence between holes and rows
 Increase bottom charge

Backbreak
 Reduce charge in holes of last row
 Reduce number of rows
 Reduce burden size
 Adjust delay times between rows
 Adjust stemming length and material size

Misfires
 Check circuit resistance
 Check connections
 Check geological discontinuities
 Adjust delay times
GEOMINING GUIDE FOR CEMENT QUAARY MANAGER – Designing Surface Blasting Rounds
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Thank You
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