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Evaluation of the Environmental Impacts of Blasting in Okorusu Fluorspar Mine, Namibia

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Jide Muili Akande at UNIVERSITY OF NAMIBIA,FACULTY OF ENGG. AND I.T. ONGWEDIVA, CAMPUS.
Jide Muili Akande
  • UNIVERSITY OF NAMIBIA,FACULTY OF ENGG. AND I.T. ONGWEDIVA, CAMPUS.
Adeyemi Aladejare at University of Oulu
Adeyemi Aladejare
Abiodun Ismail Lawal at Federal University of Technology, Akure
Abiodun Ismail Lawal
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ABSTRACT Blasting is one of the main methods used in the mining industry to fragment hard rock minerals. Blasting is an inherently dangerous activity which can result in serious injury, death, and/or damage if not designed and performed professionally. The work done in this paper is to evaluate these negative factors associated with blasting operations to the mining environment. Four different monitoring places (Mine Offices, Old Crusher, New Crusher and the Mine Hostel) in the mine were selected. Five experimental trial blasts were conducted as from the 14th to 28th November at various pits (D and B Pits) of the mine during the period of field investigation with varying designs and charging patterns. The magnitude of ground vibration and air blast, sound level data evaluated varied between 1.402 and 11.304 mm/s, 0.00354 and 0.0214 Kpa, 104.963 and 120.599 Lp (dB) respectively. Both the magnitude of ground vibration and air pressure were well within the safe limit, however the level of sound generated(120.599 Lp(dB) ) from Blast No. 5 near the Old crusher, located at a distance of 771.07 m from the blasting site, it was slightly higher than the maximum safe limit of 120 Lp(dB). This indicates that blasting operations in Okurusu Fluorspar Mine are done without noticeable environmental hazards.
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International Journal of Engineering and Technology Volume 4 No. 2, February, 2014
ISSN: 2049-3444 © 2014 – IJET Publications UK. All rights reserved.
101
Evaluation of the Environmental Impacts of Blasting in Okorusu Fluorspar
Mine, Namibia.
Akande J.M., Aladejare A.E. , Lawal A.I.
Department of Mining Engineering, Federal University of Technology, Akure . Nigeria.
ABSTRACT
Blasting is one of the main methods used in the mining industry to fragment hard rock minerals. Blasting is an inherently dangerous
activity which can result in serious injury, death, and/or damage if not designed and performed professionally. The work done in this
paper is to evaluate these negative factors associated with blasting operations to the mining environment. Four different monitoring
places (Mine Offices, Old Crusher, New Crusher and the Mine Hostel) in the mine were selected. Five experimental trial blasts were
conducted as from the 14
th
to 28
th
November at various pits (D and B Pits) of the mine during the period of field investigation with
varying designs and charging patterns. The magnitude of ground vibration and air blast, sound level data evaluated varied between 1.402
and 11.304 mm/s, 0.00354 and 0.0214 Kpa, 104.963 and 120.599 Lp (dB) respectively. Both the magnitude of ground vibration and air
pressure were well within the safe limit, however the level of sound generated(120.599 Lp(dB) ) from Blast No. 5 near the Old crusher,
located at a distance of 771.07 m from the blasting site, it was slightly higher than the maximum safe limit of 120 Lp(dB). This indicates
that blasting operations in Okurusu Fluorspar Mine are done without noticeable environmental hazards.
Keywords: Blasting, Mine, Air blast, Impact, Fly rock
1. INTRODUCTION
Mining industries and mining practice in particular, are vastly
known for their hazardous working conditions and the unstable
nature of the earth crust which mineral extraction causes
thereby threatening the life and properties of the society
(Abubakar et al., 2011). In any surface mines, blasting
operation plays a vital role. The extraction of moderately hard
mineral such as Diamond, Copper, and Gold etc. requires the
use of explosive energy through blasting to free the rock from
its in-situ position. Blast operations in mines are usually
accompanied by seismic effects which include, ground
vibrations, air-blast/overpressure/noise; fly rock, fumes and
dusts. Inappropriate planning, design and field operational
errors of blasts including unpredictable site conditions,
variability of rock mass properties and characteristics of
explosives and accessories could cause undesirable impact in
the vicinity of blast operation (Akande and Awojobi, 2005).
The undesirable known side effects of detonation of explosives
are vibration, noise/air over-pressure, flyrock, dust and fumes
(Singh et al., 1996).
Air and ground vibration from blasting is an undesirable side
effect of the use of explosives for excavation. The actual
damage criterion of ground vibration is the Peak Particle
Velocity (PPV) of the conducting ground medium or wave
acceleration (Mohamed, 2010). The shaking of structure is also
directly and linearly proportional to ground vibration amplitude.
If the PPV is reduced by half, structural response will be cut in
half (Rudenko, 2002). Complete avoidance of superposition and
amplification of the vibrations in a larger blast impossible to
achieve because the duration of the vibration is always
considerably larger than the effective delays used between the
charges in smaller blasts (Singh et al., 2003; Valdivia et al.,
2003).
Flyrock being propelled rock fragments by explosive energy
beyond the blast area, is one of the undesirable phenomena in
the mining blasting operation (Stojadinovic et al., 2011), any
mismatch between distribution of explosive energy, mechanical
strength of rock mass and charge confinement can be cause of
flyrock (Bajpayee et al,. 2004). The blasting operation is a
potential source of numerous environmental and safety
accidents. For instance, the Mine Safety and Health
Administration (MSHA, 2006) reports a total of 168 blasting
related injuries in the United States between 1994 and 2005. A
total of 107 injuries occurred in surface coal, metal and non-
metal mining, while 61 injuries were reported for underground
mining. Analysis conducted by Verakis and Lobb (2007) shows
that in surface mining, 39 accidents were directly attributed to
lack of blast area security, 32 to flyrock, 15 to premature blast,
nine to misfires, one to disposing and seven to miscellaneous
blasting-related accidents. It can be noted that almost 70% of all
injuries is directly contributing to the flyrock and lack of blast
area security. Study conducted by Lu et al. (2000) indicates that
almost 27% of demolition accidents in China were contributed
to flyrock, while Adhikari (1999) reports that 20% of accidents
that were related to flyrock occurred in mines in India.
The aim of this research is to evaluate the environmental
impacts namely: Air blast, Sound , ground vibration and
International Journal of Engineering and Technology (IJET) – Volume 4 No. 2, February, 2014
ISSN: 2049-3444 © 2014 – IJET Publications UK. All rights reserved.
102
flyrock, as a result of blasting operation in Okurusu Fluorspar
Mine in Namibia.
1.1 Site Location And Geology
The Okorusu Fluorite Mine is situated to the north of
Otjiwarongo, Namibia. The Mine is owned by Okorusu
Fluorspar (Pty) Ltd, a subsidiary of the Solvay S.A Group. The
Mine produces acid-grade fluorspar of 97% purity, with full
mineral processing facilities on site. Fluorite is associated with
an alkaline igneous-carbonatite ring dike complex. The
complex is of early Cretaceous age, which intruded into late
Pre-cambrian Damara Series metasedimentary rocks. The
metasedimentary rocks have been thoroughly fenitized in the
vicinity of the igneous intrusives to fine-grained sodic fenites.
The early main intrusion of carbonatite (sövite) is fine grained
and consists almost entirely of calcite.
Figure 1: View of the Okorusu Fluorspar mine
2. METHODOLOGY
Five trial blasting were done and four monitoring points were
used namely; Old Crusher (Plant), New Crusher, Main offices
building and Hostel. Generally, Empirical approach was
adopted in evaluating the various disasters associated with
blasting operation. The following formulas were used to
calculate selected blasting associated disasters and the results
presented thereafter in tables.
1. Air blast (kPa)
(1)
Where: P is pressure (kPa), K is state of confinement, Typical
K factors :Unconfined= 185 , Fully confined= 3.3
Q is maximum instantaneous charge (kg), R is plane distance
from charge/ blasting location (m)
2. Sound level
(2)
International Journal of Engineering and Technology (IJET) – Volume 4 No. 2, February, 2014
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103
Where: P is pressure (kPa)
3. Maximum particle vibration
(3)
Where: V is peak particle velocity (mm/s), K is site and rock
factor constant, Typical K factors: Free face – hard or highly
structured rock = 500, Free face average rock = 1140, heavily
confined= 5000, Q is maximum instantaneous charge (kg), B is
constant related to the rock and site (usually -1.6), R = distance
from charge (m)
3. RESULTS
The results obtained during the first to five trial blasts are shown in Tables 1-5 below respectively.
Table 1: The air blast, sound level and ground vibration generated during the first blast trial.
Monitoring
point
Distance from the blasting
location to the monitoring
point .(m)
Air Blast (kPa)
Sound level
Lp(dB)
Fly rocks
Old
crusher(Plant)
981.53
0.016266633
118.2053534
7.276386101
Not observed
New Crusher
992.67
0.016047822
118.0877218
7.14617464
Not observed
Main offices
building
1381.68
0.010791778
114.64126
4.210265727
Not observed
hostel
1887.3
0.007422887
111.3908568
2.55632435
Not observed
Table 2: The air blast, sound level and ground vibration generated during the second trial blast.
Monitoring
point
Plane distance from the
blasting location to the
monitoring point .(m)
Air Blast (kPa)
Sound level
Lp(dB)
Fly rocks
Old
crusher(Plant)
911.36
0.01274708
116.0876141
4.182643475
Not observed
New Crusher
923
0.012554419
115.9553324
4.098567264
Not observed
Main offices
building
1312.11
0.008231412
112.2888874
2.334545786
Not observed
hostel
1729.77
0.005908165
109.4084526
1.500283771
Not observed
Table 3: The air blast, sound level and ground vibration generated during the third trial blast.
Monitoring point
Plane distance from the
blasting location to the
monitoring point .(m)
Air Blast (kPa)
Sound level
Lp(dB)
Ground Vibration
(mm/s)k =1140
Fly rocks
Old
crusher(Plant)
1064.42
0.011283705
115.0284343
3.715659716
Not observed
New Crusher
1105.37
0.010783957
114.6349628
3.497876713
Not observed
Main offices
building
1494.77
0.007507548
111.489362
2.158230268
Not observed
hostel
1956.51
0.005435116
108.6835772
1.402960555
Not observed
International Journal of Engineering and Technology (IJET) – Volume 4 No. 2, February, 2014
ISSN: 2049-3444 © 2014 – IJET Publications UK. All rights reserved.
104
Table 4: The air blast, sound level and ground vibration generated during the fourth trial blast.
Table 5: The air blast, sound level and ground vibration generated during the fifth trial blast.
Monitoring
point
Plane distance from the
blasting location to the
monitoring point .(m)
Air Blast (kPa)
Sound level
Lp(dB)
Ground Vibration
(mm/s)k =1140
Fly rocks
Old
crusher(Plant)
771.07
0.021429641
120.5996978
771.07
Not observed
New Crusher
1003.73
0.015616625
117.8511435
1003.73
Not observed
Main offices
building
1275.28
0.011716578
115.355416
1275.28
Not observed
hostel
1654.37
0.0085737
112.6427657
1654.37
Not observed
4. DISCUSSION
Air blast
The levels of air overpressure recorded from different blasts varied between 0.00354 and 0.0214 Kpa. The Internationally accepted
damage levels due to blast-induced air blast/overpressure are shown in Table 6.
Table 1: The Internationally accepted damage levels due to blast-induced air blast/overpressure
Overpressure (dB)
Overpressure (KPa)
Air Blast Effects
177
14.00
All windows break
170
6.00
Most windows break
150
0.63
Some windows break
140
0.20
Some plate glass windows may break and rattle
136
0.13
USBM interim limit for allowable air blast
126
0.05
Complaints likely
Monitoring point
Plane distance from the
blasting location to the
monitoring point .(m)
Air Blast
(kPa)
Sound level
Lp(dB)
Ground Vibration
(mm/s)k =1140
Fly rocks
Old crusher(Plant)
732.26
0.00838814
112.4527137
1.499566855
Not observed
New Crusher
917.19
0.006401959
110.1056577
1.045912692
Not observed
Main offices
building
1218.08
0.00455463
107.1484616
0.664276717
Not observed
hostel
1502.12
0.003541755
104.96377
0.475010189
Not observed
International Journal of Engineering and Technology (IJET) – Volume 4 No. 2, February, 2014
ISSN: 2049-3444 © 2014 – IJET Publications UK. All rights reserved.
105
Figure 2: Plot of air blast / air over-pressure (kPa) at different locations
The graph in Figure 2 shows the air blast / air over-pressure
(kPa) at four different monitoring places (New Crusher , Old
crusher(Plant), Main offices building and hostel) during the five
experimental trial blast.
From Table 6 and Figure 2, it is discovered that the levels of air
overpressure recorded during experimental trial blasts were well
within the safe limits of the Internationally accepted damage
levels due to blast-induced air overpressure.
Sound level (Noise)
The levels of noise recorded from different blasts varied
between 104.963 and 120.599 Lp (dB). The Internationally
accepted Minimum levels quoted AS 2187.2 – 1993 are given
in Table 7.
Table 7: The Internationally accepted Minimum/ accepted levels quoted AS 2187.2 – 1993
Sound level effects
Minimum levels [dB(lin)]
Human discomfort
120
Onset of structure damage, or historic buildings where no
specific limit exists
130
Internationally Accepted
Damage Level
Measured Air Blast
International Journal of Engineering and Technology (IJET) – Volume 4 No. 2, February, 2014
ISSN: 2049-3444 © 2014 – IJET Publications UK. All rights reserved.
106
Figure 3: Plot of sound level (noise) Lp (dB) at di9fferent locations
Figure 3 shows the sound level (noise) experienced at four
different monitoring places (New Crusher , Old crusher(Plant),
Main offices building and hostel) during the five experimental
trial blast.
From Table 7 and Figure 3, it is shown that the sound levels
recorded during experimental trial blasts were within the safe
limits of the Internationally accepted Minimum/ accepted
sound(noise) levels quoted AS 2187.2 – 1993 except for people
working at the new crusher who affected by the noise produced
during the 5
th
blast, because the sound level at the old crusher
due to the blast five, is 120.5996978 Lp(dB) which is slightly
higher than the minimum sound level of Human comfort.
Ground vibration (Peak Particle Velocities)
When an explosive is detonated in a blast hole, a pressure wave
is generated in the surrounding rock. As this pressure wave
moves from the borehole it forms seismic waves by displacing
particles. The particle movement is measured to determine the
magnitude of the blast vibration.
The likely peak vibration amplitude is referred to as Peak
Particle Velocity (PPV) and is used as a basis for damage
limiting criteria together with blasting frequency. For various
distance from the blasting site to the area of concern, Vibration
has several negative impacts to the mining environment. The
peak particle velocity from different blasts varied between
1.402 and 11.304 mm/s. The Internationally accepted and
recommended maximum Peak Particle Velocities (AS 2187.2 –
1993) are given in Table 8.
Table 8: Recommended maximum Peak Particle Velocities (AS 2187.2 – 1993)
Type of structure/ vibration effects
Maximum Peak Particle Velocities PPV (mm/s)
Lower limit for damage to plaster walls
13
Lower limit for dry wall structures
19
Commercial and industrial buildings or structures of
reinforced concrete or steel constructions
25
Minor damage
70
>50% chance of minor damage to structures
140
Internationally Accepted
Sound Level
Measured Sound Level
International Journal of Engineering and Technology (IJET) – Volume 4 No. 2, February, 2014
ISSN: 2049-3444 © 2014 – IJET Publications UK. All rights reserved.
107
50% chance of major damage
190
Figure 4: Plot of Ground vibration (Peak Particle Velocities) ( mm/s) at different locations
The graph in Figure 4 shows the Peak Particle Velocities at four
different monitoring places (New Crusher, Old crusher (Plant),
Main offices building and hostel) during the five experimental
trial blasts. From Table 8 and Figure 4, it is clear that the Peak
Particle Velocities (Ground vibration) at the four monitoring
places during the five experimental trial blasts were all within
the safe limits of the internationally accepted / recommended
maximum Peak Particle Velocities (AS 2187.2 – 1993).
Fly rocks
During the five experimental trial blasts, there were no fly rocks
observed at all the monitoring places. This shows that accurate
blasting controlled was carried out during the five blast
experimental trial.
5. CONCLUSION
This study revealed that the blasting operation in Okorusu mine
followed the internationally acceptable standards except in a
location during the fifth trial blast where the sound level was
slightly higher than the recommended level.
Generally, it can be concluded that blasting operation at
Okurusu mine is within the international Standard and this fault
the general belief that mining operation cannot be carried out
without accompanying environmental hazards.
However, training of personnel involved in blasting operations
would continually update the workers on the improved
methodologies of blasting from time to time especially in areas
of preventing environmental and safety accidents,
implementing work practices that meet specified legislation and
standards, identifying strategies for monitoring and updating
safety information and effective safety communications.
Acknowledgement
The authors wish to acknowledge the efforts of Nekwaya
Tuyenikelao. T ( Student of University of Namibia) and the
authority of Okurusu Fluorspar Mine, Namibia for the
permission granted the researchers to carry out experimental
trial blasts in their mine.
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  • Jan 2022
Sistem penambangan batubara di Tambang Banko Pit 1 Utara adalah strip mining dengan sistem shovel-dump truck. Jenis material terdiri dari top soil, claystone, siltstone dengan strength 0,2 – 3 Mpa dan sebagian perlu diledakkan. Untuk menunjang kinerja excavator perlu dilakukan pemberaian overburden terlebih dahulu menggunakan ripper Komatsu D375A-5. Berdasarkan nilai kuat tekan (strength) material, spesifikasi ripper dan excavator yang digunakan, produktivitas excavator PC-2000 masih belum optimal karena kedalaman penggaruan hanya 1,2 m, sedangkan kedalaman garuk dari PC-2000 bisa mencapai 2,5 m, akibatnya bucket excavator masih mengambil material yang belum digaru. Untuk meningkatkan produktivitas excavator PC-2000 dalam pemberaian material, perlu dilakukan aktivitas peledakan terhadap overburden tersebut. Peledakan ini hanya untuk meretakkan overburden tersebut mengingat material termasuk kategori very soft strength rock. Tujuan penelitian ini untuk mengoptimalkan produktivitas excavator Komatsu PC-2000 dan melakukan evaluasi rancangan teknis peledakan sehingga tidak menimbulkan dampak negatif terhadap area pemukiman warga di sekitar tambang. Rekomendasi untuk optimalisasi ripping yaitu mengganti ripper yang lebih besar (Komatsu D475A-5) dengan penggaruan mencapai 2,5 m atau mengganti excavator yang lebih besar (PC-3000) dengan digging force yang lebih besar. Rekomendasi rancangan teknis peledakan untuk overburden adalah dengan sistem nonel, pengisian bahan peledak bottom air deck menggunakan bit diameter 200 mm dan geometri peledakan menggunakan burden 8 m, spacing 9 m, dan kedalaman lubang ledak 8 m.
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... Blasting is achieved with the aid of explosive capable of releasing very high energy when detonated. Part of the explosive energy released at the detonation font actualizes the actual splitting/fragmentation of rocks while the remaining energy is released to the environment resulting in various detrimental environmental effects such as blastinduced ground vibration, flyrocks, air overpressure, etc. (Akande et al. 2014;Lawal 2020;Lawal and Kwon 2020;Lawal et al. 2021). The recent expansion of the cities has made quarries in recent time to be in close distance to the residential structures. ...
Predicting the peak particle velocity from rock blasting operations using Bayesian approach
Article
Full-text available
  • Feb 2022
Measuring the blast-induced ground vibration at blasting sites is very important, to plan and avoid adverse effects of blasting in terms of the peak particle velocity (PPV). However, the measurement of PPV often requires time, cost, and logistic commitment, which may not be economical for small-scale mining operations. This has prompted the development of numerous regression equations in the literature to estimate PPV from a relatively easier to estimate scaled distance (SD) measurement. With numerous regression equations available in the literature, there is a challenge of how to select the appropriate model for a specific blasting site, more so that rocks behave differently from site to site because of different geological processes that rocks are subjected to. This study develops a method that selects appropriate models for specific blasting sites by comparing the evidence and occurrence probability of different regression models. The appropriate model is the model with the highest evidence and occurrence probability given the available blasting site SD data. The selected model is then integrated with prior knowledge and available blasting SD data in Bayesian framework for probabilistic characterization of PPV. The SD and PPV data at the opencast coal mine, Jharia coalfield in the Dhanbad district of Jharkhand, India, is used to illustrate and validate the approach. The mean and standard deviation of simulated PPV samples from the proposed approach are 12.38 mm/s and 7.36 mm/s, respectively, which are close to the mean of 12.03 mm/s and standard deviation of 9.24 mm/s estimated from the measured PPV at the site. In addition, the probability distribution of the simulated PPV samples is consistent with the probability distribution of the measured PPV at the blasting site.
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... Also, high level of profesionalism will be imperative during charging for rock displacement. However, in both cases, the severity of the environmental impact of blasting is an issue of concern because large percentage of the explosive energy may stray to the environment in form of the blast-induced ground vibration, flyrock, air overpressure, etc. (Akande et al. 2014) and lead to various degrees of havoc within and outside the circumference of the blasting region ( Fig. 1) (Raina et al. 2014). ...
Prediction of blast-induced ground vibration using GPR and blast-design parameters optimization based on novel grey-wolf optimization algorithm
Article
  • May 2021
Blasting is an intrinsic component of mining cycle of operation. However, it is usually associated with negative environmental effects such as blast-induced ground vibration (BIGV) which require accurate prediction and control. Therefore, in this study, Gaussian process regression (GPR) has been proposed for prediction of BIGV in terms of peak particle velocity (PPV), while grey-wolf optimization (GWO) algorithm has been used to optimize the blast-design parameters for the control of BIGV in Obajana limestone quarry, Nigeria. The blast-design parameters such as burden (B), spacing (S), hole depth (Hd), stemming length (T), and number of holes (nh) were obtained from the quarry. The distance from the blasting point to the measuring point (D) and the charge per delay (W) were measured and determined, respectively. The PPV was also measured for the number of blasting operations witnessed. These seven parameters were used as inputs to the proposed GPR model, while the PPV was the targeted output. The performance of the proposed model was evaluated using some statistical indices. The output of the GPR model was compared with ANN model and three empirical models, and the GPR model proved to be more accurate with the coefficient of determination (R2) of approximately 1 and variance accounted for VAF of about 100%, respectively. In addition, the GWO was also developed to select the optimum blasting parameters using the ANN model for the generation of objective function. The output of the GWO revealed that if the number of holes (nh) can be reduced by 45% and W by 8%, the PPV will be reduced by about 94%. Hence, the proposed models are both suitable for prediction of PPV and optimization of blast-design parameters.
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... However, the air overpressure which is 68 airborne shock waves originating from the detonation of explo-69 sives has been considered inconsequential for long not until the 70 1970s [34] when the importance of the air overpressure is realised 71 and guidelines and instruments for its measurements were made 72 available. The airblast also has severe environmental effects such 73 as breaking of window glass, cracking of structures, annoyance, 74 and court cases [1,11,13]. Therefore, the prediction of air overpres-75 sure is highly paramount. 76 Owing to the imperativeness of the air overpressure in blasting 77 operation, various efforts have been made by the researchers 78 [11,13,14,16,17,20,29,37] to measure the air overpressure using 79 field measurements, empirical model and soft computing method. ...
Prediction of an environmental impact of tunnel blasting using ordinary artificial neural network, particle swarm and Dragonfly optimized artificial neural networks
Article
  • Oct 2021
  • APPL ACOUST
Blasting is an intrinsic component of surface and underground excavation but it is associated with adverse environmental effects that can threaten the safety of lives and property. This study, therefore, proposed artificial intelligence (AI) based models for predicting the air overpressure (Aop) in the tunnel blasting. Three AI models which are ordinary artificial neural network (ANN), particle swarm optimized artificial neural network (PSO-ANN) and Dragonfly optimized artificial neural network (DA-ANN) are proposed. The input parameters into the models are the charge per delay (Cd), the number of holes (Nh), distance from the measuring station to the blasting point (Dm), and the rock mass rating (RMR) while the Aop is targeted output. The model parameters were obtained through field measurements and laboratory experiment. The performance of the models was evaluated using the coefficient of determination (R²), mean-squared error (MSE), mean absolute percentage error (MAPE), and the variance accounted for (VAF). Out of the different model simulations, the PSO-ANN model with 4-15-15-1 architecture performed best with R² of 1, 0.984, 1, 0.9985, MSE of 0.0004, 0.125, 5.5E-0.6, 0.018, MAPE of 0.004, 0.152, 0.002, 0.025, and VAF of 99.996, 98.29, 1, 98.85 for the respective training, testing, validation and overall datasets. The selected model was compared with the MLR model and empirical model predictions. The proposed model outperformed them. Hence, the proposed model can predict Aop with a high degree of accuracy.
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... Propelled flyrock can travel a distance greater than 600 m at a speed that can reach 650 km/h [14]. According to several studies conducted in this field, flyrock caused 27% of explosive-related accidents in China [23], while it accounted for 20% of blasting accidents in India [27]. ...
A review of some nonexplosive alternative methods to conventional rock blasting
Article
Full-text available
  • Apr 2021
The conventional blasting rock excavation method is the main means of rock breakage because of its high productivity, and it is relatively inexpensive compared to other methods. However, it raises safety concerns and can negatively impact the environment. The major disturbances that may be induced by this method include flyrock, gas emissions, and vibrations. This review discusses some nonexplosive rock breakage methods, particularly the hydraulic splitter and expansive chemical agents, that can be employed instead of the conventional blasting method and analyzes their potential effectiveness in rock breakage. Hydraulic splitting machines and expansive chemical agents were studied in the context of the literature. This review showed that hard rock breaking can be executed effectively and safely using alternative methods, which have a wide range of advantages, including safe operation, ease of use, and environmental friendliness, over conventional explosive methods. Moreover, as modern nonexplosive methods, hydraulic splitting machines and expansive chemical agents can generate pressure of up to 43 and 30–44 MPa to induce stresses in rocks, respectively. Owing to safety and environmental restrictions on conventional blasting, the application scope of the modern methods can be increased in the future.
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Assessment of Health Impacts of Rock Blasting Activities on Ntotoroso and Gyedu Communities, Ahafo Region, Ghana
Article
  • Jun 2024
The study assessed the health impact of rock blasting on the inhabitants of a farming community near the Newmont Gold Mining Limited mines in Ghana. The study employed both primary and secondary data sources, including questionnaires, interviews, laboratory water quality analysis, and record data for blasting and air quality. The study found that blast vibration, frequency, and overpressure values were above the EPA reference limits of < 88dB, 20 Hz and 2.0 mm/s respectively. All the dust concentrations of TSP and PM10 were found to be within the WHO guidelines except for the major dry seasons (December to February). Also, the respondent survey shown that a majority of respondents suffer from various symptoms such as cough (56.51%), sneezing (72.92%), catarrh (88.28%), sore throat (55.21%), shortness of breath (69.53%), headache (55.21%), and asthma (8.59%). There were, however, significant differences between blasting exposure and the occurrence of chronic cough, catarrh, headache and short breath (p < 0.05). In addition, all the heavy metal parameters were found to be within the WHO guidelines except manganese (Mn). The results of this study are expected to influence relevant stakeholders toward initiating plans that could mitigate the negative mining impacts and avert the related health implications in the study community.
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Analyzing the Devil’s Quadrangle of Process Instances Through Process Mining
Chapter
  • Jan 2024
The Devil’s Quadrangle is a framework used in Business Process Management to describe the inherent process performance trade-offs regarding the time, costs, flexibility, and quality dimensions. In practice, improving a process through one of these dimensions might have a negative effect on the performance of the other dimensions. The dimensions considered by the Devil’s Quadrangle are often used for defining indicators that illustrate the overall performance of processes. From a Process Mining perspective, analyzing these dimensions at higher granularity levels, such as for every process instance, is of interest. To achieve this, this work proposes a method for defining Process Mining filters based on metrics related to performance indicators of the four Devil’s Quadrangle dimensions. The metrics are calculated for every process instance, which allows using the filters to observe differences in process behavior while considering constraints to the performance indicators and trade-offs among the four dimensions. It is expected that this visualization will be helpful during exploratory process analysis. It will facilitate the identification of process instances that conform to the filters applied to the performance indicators, as well as the dimensions where improvement is required while considering process instances that do not conform to the applied filters. A Celonis dashboard with the proposed filters has been generated to validate the method.
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Potato (Solanum tuberosum L.) Production under Phosphate-mining Wastewater in Jordan
Article
  • Apr 2011
This study is concerned with potato performance under phosphate mining waste water as an alternative sustainable source of water. It was conducted in Al-Quwayrah area south of Jordan. Class (A) tubers of (Spunta and Mondial) potato (Solanum tuberosum L.) cultivars were planted under drip irrigation system. Water from phosphate mining activities, hybrid water (consisting of 50% fresh and 50% mine wastewater) and fresh groundwater were tested. Water, soil and tuber samples were evaluated for each plot and analyzed for heavy metal (Ni+2, Zn+2 and Pb+2) in addition to major ionic composition of the water used for irrigation. Potato vegetative growth, tuber specific gravity and yields were estimated at the end of the experiment. The fresh groundwater showed the lowest vegetative dry matter content (15.1%) compared to those of the mining water (16.9%) which was significantly similar to those (16.3%) of the hybrid water. Phosphate mining water showed yield reduction of 11.9 and 16.3% of those of the hybrid and the freshwater, respectively. Generally, Ni, Zn and Pb concentrations in the potato tubers were varied among treatments of water types used, with tendency of higher concentrations in the tubers of mining water. Soil site contents of Ni and Zn at the end of the study, were significantly increased due to mining and hybrid water, while Pb contents were not affected by water types used. According to results obtained, phosphate mining waste water can be used in potato fields and can be part of crop irrigation regimes.
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Vibration Simulation Method to Control Stability in the Northeast Corner of Escondida Mine
Article
  • Jun 2003
Vibrations due to production blasting can induce damage to the rock mass at large distances by altering larger geological structures, fault areas or other structures, where the orientation with respect to the mine geometry is unfavorable and can cause displacement of large rock volumes. Past occurrences of this nature in Escondida Mine placed geomechanical safety restrictions as to maximum allowable blast size in the northeast area of the mine. These restrictions limited the efficiency of drilling and blasting operations seriously limiting daily production. This is what prompted this study to attempt to increase shot size while reducing stability problems. This would permit keeping stable the slope over which the ore extraction belts are located, as well as the main access ramp to the mine. Using a rigorous and systematic instrumentation and monitoring effort of blasting vibrations at multiple locations with respect to an unstable location allowed the development of a database to establish acceptable vibrations limits. A parallel effort was the development and gauging of a mechanistic model for the prediction and simulation of blasting vibrations. Excellent results were obtained from a comparison between the measured and predicted results. This allowed the use of the gauged model to verify the practicality of increasing the shot size in the restricted blasting zones, without exceeding safe vibration limits. The practical success achieved using this research approach resulted in increased blasting size, with a consequent increase of blasted material per shot, and contributed to more flexible mining operations.
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Blasting side effects - Investigations in an opencast coal mine in India
Article
  • Jan 1996
Field investigations were conducted in a potential opencast coal mine in India with a view to optimizing blast patterns for controlling ground vibration, sound pressure level and fly rock within safe and tolerable limits. Blasting was performed in all operating benches i.e., alluvium, sandstone, shale, coal and blast vibrations were monitored on the alluvial soil present in the vicinity of the mine. It was observed that in all the blasting rounds, low frequency ground vibrations were generated. Further investigations were carried out by recording structural response to ground vibration on single and double storied buildings. It was observed that the ground vibrations were amplified by structures themselves, as much as 2.0 to 5.6 times
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Studies on Flyrock at Limestone Quarries
Article
  • Jan 1999
Observed flyrock distances for 47 blasts at six limestone quarries along with blast design parameters are presented. The influence of blasthole diameter, burden, stemming length, powder factor, the condition of blastholes (dry or wet) and the initiation systems on generation of flyrock is analysed and the most critical parameters for flyrock control are identified. Based on the analysis of results, suggestions are given to minimise the flyrock hazards at limestone quarries.
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Mining injuries in Serbian underground coal mines - A 10-year study
Article
  • Sep 2011
Mining, especially underground coal mining, has always been a dangerous occupation. Injuries, unfortunately, even those resulting in death, are one of the major occupational risks that all miners live with. Despite the fact that all workers are aware of the risk, efforts must be and are being made to increase the safety of mines. Injury monitoring and data analysis can provide us with valuable data on the causes of accidents and enable us to establish a correlation between the conditions in the work environment and the number of injuries, which can further lead to proper preventive measures. This article presents the data on the injuries in Serbian coal mines during a 10-year period (2000-2009). The presented results are only part of an ongoing study whose aim is to assess the safety conditions in Serbian coal mines and classify them according to that assessment.
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Blasting injuries in surface mining with emphasis on flyrock and blast area security
Article
  • Feb 2004
  • J SAFETY RES
Blasting is a hazardous component of surface mining. Serious injuries and fatalities result from improper judgment or practice during rock blasting. This paper describes several fatal injury case studies, analyzes causative factors, and emphasizes preventive measures. This study examines publications by MSHA, USGS, and other authors. The primary source of information was MSHA's injury-related publications. During the 21-year period from 1978 to 1998, the mean yearly explosive-related injuries (fatal and nonfatal) for surface coal mines was 8.86 (95% CI: 6.38-11.33), and for surface metal/nonmetal mines 10.76 (95% CI: 8.39-13.14). Flyrock and lack of blast area security accounted for 68.2% of these injuries. This paper reviews several case studies of fatal injuries. Case studies indicate that the causative factors for fatal injuries are primarily personal and task-related and to some extent environmental. A reduction in the annual injuries in surface coal mines was observed during the 10-year period of 1989-1998 [5.80 (95% CI: 2.71-8.89) compared to the previous 10-year period of 1979-1988 [10.90 (95% CI: 7.77-14.14)]. However, such reduction was not noticed in the metal/nonmetal sector (i.e., 9.30 [95% CI: 6.84-11.76] for the period 1989-1998 compared with 11.00 [95% CI: 7.11-14.89] for the period 1979-1988). A multifaceted injury prevention approach consisting of behavioral/educational, administrative/regulatory, and engineering interventions merits consideration. The mining community, especially the blasters, will find useful information on causative factors and preventive measures to mitigate injuries due to flyrock and lack of blast area security in surface blasting. Discussion of case studies during safety meetings will help to mitigate fatal injuries and derive important payoffs in terms of lower risks and costs of injuries.
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Survival of cementless dual mobility sockets: Ten-year follow-up
Article
  • Jul 2006
  • REV CHIR ORTHOP
We report a retrospective series of 106 total hip prosthesis with ten years follow-up. The purpose of this study was to analyze survival of cementless dual mobility sockets. The series included 90 consecutive patients with 106 first-intention total hip prosthesis, all with cementless dual mobility sockets. All prosthesis (Novae-1 socket and Profil-1 stem, Serf) were implanted within a 6-month period. The stainless steal socket was coated with alumina and had two short anchorage studs and a superior mooring screw and a polyethylene retentive liner. The stem had a 22.2 mm chromium cobalt head. The main indication for arthroplasty was degenerative joint disease. Mean age at implantation was 56 years (range 23-87). All patients were seen for physical examination and x-rays every two or three years. We noted cup survival at ten years (actuarial method), defining surgical revision for cup replacement due to an aseptic cause as the endpoint. Twelve patients died during the 10-year follow-up and one was lost to follow-up. The Postel-Merle d'Aubligné score improved from 7.1 preoperatively to 15.8 at ten years. There were two isolated acetabular loosenings, two intra-prosthetic dislocations due to advanced wear of the polyethylene insert. The overall survival rate of the socket was 94.6% at ten years. There were no episodes of prosthetic instability in this series. This study demonstrates the good ten-year survival of the dual mobility socket, comparable to that of conventional prostheses. The absence of any case of prosthetic instability in this series confirms the good short-term and long-term stability of the dual mobility socket. Intraprosthetic dislocation, due to loss of the polyethylene retaining ring is the main limitation of this method. The incidence was however low (2% at ten years) and treatment was not a problem. We recommend using the dual-mobility socket as the first-intention implant for patients with a high risk of post-operative instability, but also recommend it for all patients aged over 70 years since instability is the leading cause of surgical revision after this age.
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Assessment of Enivironmental Impact of Exploitation of Granitw Deposit in Iiorin
  • Jan 2005
  • 4888-4900
  • J M Akande
  • D Awojobi
Akande J.M. and Awojobi D. (2005) : Assessment of Enivironmental Impact of Exploitation of Granitw Deposit in Iiorin, Nigeria.,Journal of Science, vol. 10, no. 2, pp. 4888-4900.
Peak Particle Velocities Generated Ground Vibration
  • Mar 2014
  • Recommended Max
Recommended Max. Peak Particle Velocities Generated Ground Vibration International Journal of Engineering and Technology (IJET) – Volume 4 No. 2, February, 2014 ISSN: 2049-3444 © 2014 – IJET Publications UK. All rights reserved. 108