Report On Rock Excavation Engineering Division CSIR-CENTRAL INSTITUTE OF MINING & FUEL RESEARCH (Council of Scientific & Industrial Research) Barwa Road, Dhanbad (Jharkhand) Confidential ADVICE FOR DESIGNING OF CONTROLLED BLASTING PATTERNS AT NARAYANPOSHI IRON & MANGANESE ORE MINES, KOIRA, SUNDARGAH DISTRICT, ODISHA TO KEEP GROUND VIBRATIONS, AIR-OVERPRESSURE/NOISE AND FLYROCK WITHIN SAFE LIMITS JUNE, 2018 * C S I R - I N D I A *
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1
Report On
Rock Excavation Engineering Division CSIR-CENTRAL INSTITUTE OF MINING & FUEL RESEARCH
(Council of Scientific & Industrial Research) Barwa Road, Dhanbad (Jharkhand)
Confidential
ADVICE FOR DESIGNING OF CONTROLLED BLASTING
PATTERNS AT NARAYANPOSHI IRON & MANGANESE
ORE MINES, KOIRA, SUNDARGAH DISTRICT, ODISHA TO
KEEP GROUND VIBRATIONS, AIR-OVERPRESSURE/NOISE
AND FLYROCK WITHIN SAFE LIMITS
JUNE, 2018
*CSIR- INDIA*
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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*CSIR- INDIA*
Team Members Associated with the Project
Dr. C. Sawmliana, Principal Scientist
Sri Aditya Rana, Scientist
Sri R. K. Singh, Sr. Technical Officer (1)
Sri N. K. Bhaghat, Sr. Technical Officer (1)
Sri P. Hembram, Technical Assistant
Dr. M. M. Singh, Chief Scientist
&
Dr. P. K. Singh, Director
Rock Excavation Engineering Division CSIR-Central Institute of Mining and Fuel Research
Barwa Road, Dhanbad-826 015
Jharkhand
*CSIR- INDIA*
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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*CSIR- INDIA*
CONTENTS
Page
No.
1.0 INTRODUCTION 4
2.0 BRIEF INFORMATION AND GEOLOGY OF THE MINE 5
2.1 Brief information of the mine 5
2.2 Geology 6
2.2.1 Topography 6
2.2.2 Drainage 6
2.2.3 Vegetation 7
2.2.4 Regional Geology 7
2.2.5 Project Geology 9
3.0 INSTRUMENTS USED FOR FIELD INVESTIGATIONS 10
4.0 FIELD INVESTIGATIONS 11
4.1 Experimental Blasts 11
4.2 Monitoring of Ground Vibration and Air Overpressure/Noise 17
4.3 Study of Flyrock 24
5.0 GROUND VIBRATION AND AIR OVERPRESSURE/NOISE RESULTS 24
5.1 Ground Vibration Results 24
5.2 Air Overpressure/Noise Results 27
6.0 FLYROCK RESULTS AND OBSERVATIONS 28
7.0 ANALYSIS OF GROUND VIBRATION DATA 28
7.1 Assessment of Ground Vibration Predictor Equation 28
7.2 Assessment of Safe Values of Maximum Charge per Delay 29
8.0 SUGGESTED CONTROLLED BLAST DESIGN PATTERNS 30
9.0 ADDITIONAL CONTROLLED MEASURES SUGGESTED FOR VIBRATION AND
FLYROCK
34
9.1 Controlled Measures for Ground vibration 34
9.2 Controlled Measures for Flyrock 35
10.0 CONCLUSIONS AND RECOMMENDATIONS 37
ACKNOWLEDGEMENT 42
ANNEXURE 43
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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*CSIR- INDIA*
1.0 INTRODUCTION
Narayanposhi Iron & Mn Mines of M/s Arayan Mining & Trading Corporation
Pvt Ltd. is located at Koira and Kashira villages, in Koira Tehsil under Bonai
Sub-division of Sundergarh District, Odisha. The mines operation was started
in 1945. The Mining Lease (M.L.) area has an undulating topography with a
prominent hillock in the central part of the hill. Intervening valleys exist
between the hillocks. Altitudes vary between 540 m RL (lowest) in the
western portion of the lease to 630 m RL (highest) in the central part of the
lease. The ML has about 185Million Ton Iron ore reserve as per latest geology
study report and it may be enhanced during next geological study. The
mines EC capacity is 3.00 Million TPA Iron ore and 0.036 Million TPA
Manganese ore production.
In order to assess the blasting impacts in the form of ground vibration,
flyrock, noises etc. to the nearby villages of the mine, M/s Arayan Mining &
Trading Corporation Limited awarded a scientific study to the Rock
Excavation Engineering Division (Erstwhile Blasting Department) of CSIR-
Central Institute of Mining and Fuel Research (CSIR-CIMFR), Dhanbad,
Jharkhand. The main objective of the study was to develop safe and
optimum blast design patterns for working within the danger zone keeping
ground vibrations, noise/air overpressure and flyrocks within the safe limits for
the safety of the nearby houses of the village as per the norms set by DGMS.
The Rock Excavation Engineering Division of CSIR-CIMFR carried out field
investigations at the mine during the period of 14th to 17th May, 2018. During
this period, eight experimental blasts were conducted of different working
benches in Quarry-4 and RF Quarry. Blast induced ground vibrations and air
overpressures/noises generated during the experimental blasts were
monitored near the residential houses and important structures in
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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Naraynposhias and Kashira villages. Flyrock generated during the trial blasts
were observed and recorded in all the blasts.
This report contains the detailed field investigation, results of the
experimental blasts, analyses of the data recorded and recommendations
for safe and efficient controlled blasting parameters for day-to-day blasting
operations at Narayanposhi Iron & Mn Mines without affecting the nearby
residential houses and habitants.
2.0 BRIEF INFORMATION AND GEOLOGY OF THE MINE
2.1 Brief Information of the Mine
Narayanposhi Iron & Manganese Ore Mines of M/s Aryan Mining & Trading
Corporation Pvt. Ltd. is in the villages of Koira & Kashira and Kathamala RF,
Tehesil Koira, district Sundargarh Odisha. The total lease area is 349.254 Ha.
Mine is in operation since 1945. It is located in the Topo Sheet No. 73 G/1 &
73 G/5 with Latitude : 210 54’ 46.07” - 210 56’ 23.13” North Longitude : 850
13’ 41.16” - 850 14’ 56.56” East.
Narayanposhi Iron & Manganese Ore Mines adopt open cast, fully
mechanized method of mining with drilling and blasting. During the period
of field investigation, two pits are working viz. Quarry-4 and RF Quarry. The
excavation planning during the period of 2018 - 2019 and 2018 - 2020 are
given in Table 2.1 and 2.2.
Table 2.1. The In-situ Tentative Excavation (cum) plan of Iron Ore Zone at
For in-hole as well as surface hole-to-hole initiation, non-electric initiation
systems (Nonel/shock tube system) are recommended for controlled
blasting operations in the mine. Bottom initiation should be followed while
charging a hole using Nonel system. No detonating cord should be used for
charging of holes and surface hole-to-hole connections. In the experimental
blasts, 17 milliseconds delay TLDs were used for hole-to-hole initiation in a row
in all the blasts, except in one blast, where 25 ms delay was used. However,
25 milliseconds delay of TLDs have been recommended in place of 17 ms
TLDs, particularly for blasting operations within the blasting zone of 200 to 300
distance from the residential houses/structures of the nearby villages. For
delay between row, the minimum delays should be 42 ms. The suggested
firing pattern for multi-rows holes are given in Figures 8.1 to 8.13.
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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Fig. 8.1. Suggested firing pattern of holes for multi-row blasts using 25 ms delay between
Holes in a row and combination of 25 ms and 42 ms delays between rows.
Fig. 8.2. Firing sequence of holes and direction of rock movement obtained in the
Suggested pattern shown in Figure 8.1
Fig. 8.3. The number of holes detonated within 8 milliseconds window along with the
the detonation time obtained in the suggested pattern shown in Figure 8.1
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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9.0 ADDITIONAL CONTROLLED MEASURES SUGGESTED FOR VIBRATIONS
AND FLYROCKS
Even though controlled blast design patterns have been suggested for
controlling of ground vibration, flyrock and noise/air overpressure for the
safety of the nearby residential houses/structures, the additional controlled
measures have been suggested for further improvement in safe blasting
operations at Narayanposhi Iron & Manganese Ore Mines of M/s Arayan
Mining & Trading Corporation Ltd. in the following section.
9.1 Controlled Measures for Ground Vibrations
The intensity and characteristics of ground vibration generated from a
blasting source depend upon different parameters such as:
Local geology
Charge weight per delay
Distance from the point of blast
Delay period
Spatial distribution of explosive charge
Confinement
Type of explosive
The confinement of explosive charge such as more burden and spacing
values, deeply buried charge (excessive stemming length) and presence of
blasted material at the face (choked face) generally increase the level of
ground vibration. Explosives having lower borehole pressures also produce
lower vibration than those explosives having higher strength with more
detonation pressure.
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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The followings are some of the principal factors that can be taken into
account for reducing blast generated ground vibrations:
Minimizing the explosive charge per delay by reducing drill hole
diameter, blasthole depth, decking the explosive charges in a hole and
initiating them at different times.
Reduce the number of blastholes having instantaneous detonators by
using more number of delay detonators.
Choose effective delay time between holes and rows which avoid wave
interaction and give good rock displacement.
Set the initiation sequence in a way that it progresses away from the
structures to be protected.
Maintain bench height to burden ratio more than two and use
adequate powder factor to decrease over confinement of explosive
charge.
Use the largest possible free face blast area and avoid choked face
blasting.
9.2 Controlled Measures for Flyrock
The following suggestions and recommendations have been made as the
additional precautions for future to control flyrock.
The primary means of controlling flyrock is through proper blast design
and delay timing. The consistency of the burden, specially the front
burden (distance between the first row to free face) must be
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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*CSIR- INDIA*
maintained. Bench height to burden ratio less than 1.5 should be
avoided.
While loading a shot, the blaster must be aware of his true powder
factor in terms of the amount of explosive to be charged for the
quantity of rock to be fragmented. Charging of excessive explosive
quantity should be avoided.
The blasting site should always be inspected before marking the holes.
If any clay seams, open joints and bedding planes are present in the
bench, an adjustment should be made in the drilling pattern.
The holes should be drilled in conformity of the face. Wherever
possible, vertical holes should be preferred against the inclined holes.
Before loading, blasting officials should always check the hole depths
and ensure that the holes are drilled as per the blast design.
Any change in the blast design should carefully be considered from
the standpoint of its potential effect on flyrock.
All loosened pieces of the rock from the blasting site should be
cleared before charging.
Statutory provisions should be strictly implemented.
An injury due to lack of blast area security occurs when a person fails to stay
inside a blast shelter or in a protected location or safe distances. Accidents
due to lack of blast area security are commonly caused by the followings
which should be strictly taken care of in all the blasting operations.
Failure to evacuate the blast area by employees and visitors,
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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*CSIR- INDIA*
Failure to understand the instructions of the blaster or supervisor,
Inadequate guarding of the access roads leading to the blast area,
and;
Taking shelter at an unsafe location or inside a weak structure.
10.0 CONCLUSIONS AND RECOMMENDATIONS
Based on the results of experimental blasts conducted, observations made in
the field and analyses of the ground vibration data collected, the following
conclusions and recommendations are made for safe and optimum
controlled blasting operations at Narayanposhi Iron & Manganese Ore Mines
of M/s Arayan Mining & Trading Corporation Ltd.
(1) In total, eight rounds of experimental blasts were carried out in Quarry-
4 and RF Quarry with four blasts each in both the quarries. The
blasthole diameter used in all the experimental blasts was 100 mm. Six
experimental blasts were conducted with 83 mm diameter cartridge
explosive of 2.78 kg weight per cartridge and two blasts were
conducted with SME explosives. Nonel (shock tube) initiation systems
were used in all the experimental blasts.
(2) The total number of holes in the blasting rounds varied from 14 to 105.
The burden value used in the experimental blasts varied between 2.5
to 3.0 m and spacing varied from 3.0 to 4.0 m. Depending on the
depth of hole, the explosive charge per hole varied from 19.44 to 70.00
kg. The total explosive charge in a blasting round varied between
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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*CSIR- INDIA*
675.00 and 6,546 kg. The maximum explosive charge per delay (holes
firing within 8 ms widows) varied from 38.88 to 187.00 kg.
(3) During the experimental blasts conducted in Quarry-4, blast-induced
ground vibrations and air overpressures/noises were monitored near
the Church, Sarpanch house, temporary shops in Narayanposhi village
and haul road closer to the blasting sites, towards Narayanposhi
village. In one experimental blast, ground vibration was monitored
towards Kashira village. The distances of vibration monitoring points
from the blasting sites in Quarry-4 varied from 150 to 707 m.
(4) During the experimental blasts conducted in RF Quarry, ground
vibrations and air overpressures/noises were monitored near the labor
camp as well as on the haul road, closer to the blasting sites, towards
Labor hutments. In one experimental blast, ground vibration was also
monitored towards Kashira village also. The distances of vibration
monitoring points from the blasting sites in Quarry-4 varied from 115 to
1040 m.
(5) From the nine experimental blasts conducted during the period of field
investigation, twenty-nine ground vibration data were recorded at the
different vibration monitoring stations. Depending on the distance of
vibration monitoring point from the blasting site and the explosive
charge quantity used in the blasting round, the magnitudes of ground
vibration data recorded from all the experimental blasts varied
between 0.568 and 5.17 mm/s.
(6) The magnitudes of ground vibrations recorded near the Church in
Narayanposhi village varied from 0.813 to 1.68 mm/s. The distance of
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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*CSIR- INDIA*
vibration monitoring point near the church from the different
experimental blasting sites at Quarry-4 varied from 613 to 707 m. The
highest magnitude of vibration recorded near the Church was 1.67
mm/sec at 690 m distance with the corresponding dominant
frequency of 2.75 Hz. This was recorded during the experimental blast
conducted at 3rd Bench in Quarry-4 where the maximum charge per
delay was 187.00 kg and the total explosive charge in the blasting
round was 6546.25 kg.
(7) The magnitude of ground vibration recorded near the house of
Sarpanch in Narayanposhi village was 1.40 mm/s with the
corresponding dominant frequency of 3.13 Hz. This was recorded
during the experimental blast conducted at 3rd Bench in Quarry-4
(Experimental Blast No. B-8) where the maximum charge per delay
was 187.00 kg and the total explosive charge in the blasting round was
6546.25 kg. The distance of vibration monitoring point near the church
the experimental blasting site was 668.0 m.
(8) The magnitudes of ground vibration recorded near the Labor Camp
of the mine varied from 1.25 to 2.86 mm/s. The distances of vibration
monitoring point near the Labor Camp from the different experimental
blasting sites at RF Quarry varied from 300 to 490 m.
(9) Ground vibration data could not be recorded at the monitoring point
on ground surface towards Kashira village during the experimental
blast in Quarry-4 and RF Quarry. The distances of vibration monitoring
points from the blasting sites at Quarry-4 and RF Quarry were 460 m
and 1040 m respectively.
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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(10) The highest magnitude of ground vibration recorded on the haul road,
closer to the blasting sites was 5.17 mm/s at the distance of 155 m. The
corresponding value of dominant frequency was 22.8 Hz. This was
recorded during the experimental blast conducted at Sub-Bench in RF
Quarry where the maximum charge per delay and total explosive
charge were 38.88 kg and 875.00 kg respectively.
(11) The dominant excitation frequency of the ground vibration waves
ranged between 2.25 and 26.8 Hz. Based on the attenuation
characteristic of ground vibration waves and dominant frequencies,
the safe level of ground vibration in term of peak particle velocity
(PPV) for the residential houses/structures of the nearby villages has
been taken as 5.0 mm/s. However, for the structures belonging to M/s
Aryan Mining and Trading Cor. Ltd., PPV value of 10 mm/s has been
taken safe level for ground vibration as per the DGMS Standard
(Technical Circular Number 7 of 1997).
(12) The levels of ground vibration data obtained from the experimental
blasts conducted at Quarry-4 and RF Quarry nearby the different
structures/houses were all within the safe limits as per the DGMS
Standards.
(13) The levels of air overpressures recorded from different trial blasts varied
between 100 and 129.1 dB (L). The magnitudes of air overpressure
recorded were within the safe limits and will not cause structural
damages to the village houses.
(14) No flyrock was observed in any of the experimental blasts. The throws
of the blasted materials were also controlled and restricted within the
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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*CSIR- INDIA*
blasting areas only. The control of flyrock was achieved through
proper blast design patterns along with their proper implementation
and supervision of the total blasting operations.
(15) Ground vibration predictor equation have been established for
Narayanposhi Iron & Manganese Ore Mines and is given as Equation-
7.1 in the report. The recommended explosive weights per delay for
various distances from the village houses/structures are given in Table
7.1 in the report.
(16) Based on the analysis results of ground vibration data collected,
experimental blasts results and observations made, the blasting zones
have been classified for controlled blasting operations nearby the
residential houses/structures of the village as:
(D) 200 - 300 m from the village houses/structures
(E) 300 – 500 m from the village houses/structure
(F) Beyond 500 m from the village houses/structure
(17) Details of the suggested controlled blast design parameters for the
different blasting zones are described in Section 8.1 of the report. It is
recommended to use 25 milliseconds delay of TLDs between holes in a
row instead of 17 ms TLDs. The minimum delay between rows should
also be 42 ms.
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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*CSIR- INDIA*
Acknowledgement
The research team are thankful to the management of M/s Arayan Mining &
Trading Corporation Ltd. for awarding the study to CSIR-CIMFR, Dhanbad.
They also thankfully acknowledge the sincere cooperation and help
extended to them during the period of field investigation by the following
officials M/s Arayan Mining & Trading Corporation Ltd and M/s Thriveni
Earthmover Private Limited.
CSIR-Central Institute of Mining & Fuel Research (CSIR-CIMFR), Dhanbad-826015
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*CSIR- INDIA*
ANNEXURE
44
Table-A1: Details of experimental blasts conducted at Narayanposhi Iron & Mn Ore Mines of M/s Aryan Mining & Trading Corp. Ltd, Koira, Sundergarh, Odisha