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By Charles Deacon

The mining industry is constantly taking greater cognisance of their operating costs as a strategy to counter the effects of falling commodity prices. As a result, optimal operating efficiency is more important than ever. One such operation is that of blasting. Considering the relative increasing costs of explosives and accessories it is desirable to optimise the number of blast-holes fired by maximising their individual output. This achievement may now only be possible following the advent of higher technologies in the form of modified explosives and electronic detonators. This paper reviews and introduces some techniques of blast monitoring, types of operations where each is most suited, resulting modifications to blast designs, and identifies some pitfalls to watch out for when analysing the results.

Jan 1, 2000

By H G. Bosmare, G Bedser, C V. B Cunningham

Peak Quany has achieved substantial improvements to its bottom lie by giving close attention to blasting practice, and in pr@icnlar by introducing electronic delay detonators for routine production blasting. The precision and flexibility provided by these units has enabled the quarry to gain control over fmes and curtail oversize without increasing explosive usage. In addition, the extent of nuisance from blasting vibrations has been reduced.

Jan 1, 1998

By Adrian Moore, Alan Richards, Andrew Brodbeck

Structural blast vibration limits should be based on the strength of the structure, the stress induced by blasting, and a responsible factor of safety. In this paper a methodology that uses direct strain measurements to determine the stress induced by blasting is described. The methodology has been used to measure strain resulting from blasting, and establish appropriate blast vibration limits on a brick sewer tunnel, an underground mine heading, brick veneer houses, a water pipeline, and transmission tower foundations. An outline is given of the use of the methodology to establish limits for the main entry heading of an underground coal mine, and transmission tower footings. The methodology that is described has reduced uncertainty factors, and permitted the specification of higher blast vibration limits than had been previously used.

By Greg Wyartt

In the Pilbara region of Western Australia, an iron ore mine is undertaking a high wall cut-back to improve stability and allow access to deeper ore deposits. Several sections of the wall have been classified geologically sensitive due to unstable localised geology, and therefore an engineered approach to vibration critical blasting was required. The use of electronic detonators allowed multiple signature (seed) holes to be incorporated into a production blast adjacent to the geologically sensitive area, therefore providing baseline vibration data to be used for future modelling with the added advantage of eliminating unnecessary pit closure downtime typically associated with a signature hole program. All subsequent blast patterns also incorporated multiple signature holes to provide additional data and allow continual updating – and therefore improved accuracy - of the blast prediction model.

Jan 1, 2018

By Nikolaos Petropoulos, Daniel Johansson, Håkan Schunnesson

The optimization of the explosive performance is of great importance since blasting is extensively used in civil projects and mining industry. An improved understanding of how the energy from the detonation of an explosive is transmitted to the surrounding rock mass is critical information for the proper selection of an explosive. Therefore, an extensive study was done on the influence of the blasthole diameter on the Velocity of Detonation (VoD) and the detonation front curvature. In this study, pure emulsion was tested in confined conditions to better simulate the behavior of the detonation of the explosive in rock mass conditions. A methodology is proposed for carrying out the evaluation of the explosive performance. The blasthole diameter of the samples varied from Ø 25 mm (0.98 in) up to Ø 65 mm (2.55 in). The confiner was a magnetic mortar cylindrical sample with mechanical properties similar to a rock mass. A streak camera and VoD probes were used to measure detonation front curvature and VoD. The data was analyzed and correlated with the physical parameters of the explosive. Additional to this, the data was further used to calibrate numerical models in LS-Dyna.

By G. Adderley, A. Wetherelt

The problems of poor drilling in underground operations have been highlighted on many occasions. Incorrect collaring and poor angular deviation can all lead to an increased block size, dilution, over-break adding to both cost and time, while in a tunnelling operation sidewall damage and a poor percentage pull from a blasted round has similar consequences. This paper sets out to further investigate the ability of the laser scanner method of obtaining drill hole deviations and collaring errors at the face as described by Wetherelt and Williams (2006). Tests were carried out to compare measured inter-hole burdens from this method in comparison to that obtained using a total station survey. To investigate the ability of these methods to accurately determine drilling errors, a field test was carried out through an analysis of a series of pre-drilled blast holes of known inclination and direction. A time-motion study was also conducted for a varied number of holes to assess the usability of each method. In line with current research into blast vibration being undertaken at the Camborne School of Mines, 6 cut blasts were carried out to establish the effect of poor drilling on a blasts success to see whether an increased burden at the toe of a hole had an influence on vibration.

Jan 1, 2009

By Chulgi Suk, Hoon Park, Hyonsoo Kim, Hakman Kim, Sangho Cho

Dust emission from blast demolition and other construction activities can be a nuisance; it is widely recognized that fine particles less than 10 µm in equivalent diameter (called PM10) may cause health problems. Mist spray systems, such as rain guns, sprinklers, water/surfactant sprays (or foams) etc., are some of the most effective dust suppression methods. A large amount of research has showed that when water droplets are produced in an equal amount to that of dust particles, the airborne dust is suppressed by the agglomeration of dust and mist particles. A method for generating micro-sized mist from water, achieved by the detonation of explosives in the water tube, was suggested and is called the ‘detonationdriven water bag burst system’. There are many experimentally observed limitations of the explosioninduced water break-up process. The water bag explosion tests were simulated using the AUTODYN software, in order to investigate the aerosolization mechanisms of the detonation-driven water and water break-up process into micron-sized droplets. As a result of the numerical analyses, the diffusion direction of water when detonating in the central interior part of water tube was radioactive and significantly stronger than when detonating in the bottom exterior part; this is due to the compressive flow of the volume change inside of the water tube, which resulted from the blasting wave inside of the tube, as well as the reflected pressure on the ground. Blast tests of full-scaled reinforced concrete columns were conducted to verify the effectiveness of the suggested detonation-driven water bag burst system. The water breakdown and dispersion that occurred while blasting the reinforced concrete columns were observed using a high-speed camera, and dust generation was monitored using four density detectors. The suggested detonation-driven water bag burst system showed that the average dust density decreased by up to 7 mg/m3.

Jan 1, 2016

By R Yang, M Lownds

This paper reports studies showing the effects of delay scatter on the peak particle velocity (PPV) of blast vibration using a multiple seed wave (MSW) vibration model developed in recent years. The case studies also show the advantage of accurate delay timing on frequency control of blast vibration. The site parameters used in one of the studies are from a case in which the MSW model has been tested and confirmed to yield accurate predictions. This study uses an open pit blast design and a tunnel design in which blast vibrations using electronic detonators are compared with those from pyrotechnic detonators. Mean peak particle velocity (PPV) and the 97.5% upper bound PPV are compared. It is found that both these values increase significantly with the increase of the coefficient of variation of the site parameter. Using an open pit blast design, the modeling shows that electronic initiation shifts vibration energy to the expected frequency for a selected point of interest. However, for the same design of nominal initiation timing pyrotechnic detonators fail to shift vibration to the expected frequency due to its large scatter of timing.

Jan 1, 2011

By Steve Colburn

The CRITERION Survey Systems utilize both theodolite mounted and hand held reflectorless distance meters. These are eye safe, easy-to-use, and specifically designed to endure the harsh environments characteristic to the mining, quarry and explosives industries. Survey data collected by the systems is digitally stored in a ruggedized data collector and then processed with a specialized, Windows-based, interactive software program which can be run on any standard PC.

Jan 1, 1997

By Dean Nichols, Matt Ortel

Explosive accidents in the United States have brought increased attention to emergency operation plans (EOP) at all facilities that manufacture, transport, or store hazardous materials – particularly explosive materials. Explosions are sudden, powerful, and complex events that are difficult to characterize in terms of the thermal, over pressure, and debris effects. Industry, regulatory, and public officials require emergency response planners to not only anticipate the blast effects of an explosion, but also to prepare an appropriate response.

Jan 1, 2016

By C B. McCampbell, R W. Jr Bickes

Sandia National Laboratories has developed a semiconductor bridge (SCB) igniter for the ignition of a variety of explosive materials. When subjected to a low-energy current pulse, the bridge bursts into a plasma causing rapid ignition of the explosive material pressed against the bridge. Despite the low energies required for ignition, SCB components have proven to be explosively safe, meeting both no-fire and electrostatic discharge (ESD) safety requirements.

Jan 1, 1991

By Ali Kahriman, Abdulkadir Karadogan, Umit Ozer, Mehmet Aksoy, Kagan Ozdemir, Adiguzel Deniz

This paper presents the results of ground vibration measurements induced by blasting during the construction of the Istanbul Kadiköy-Kartal metro tunnel which has been driven at a depth of approximately 20-40 m deep under a highly urbanized region of Istanbul city in Turkey. This tunnel is being constructed by a joint venture group. The formation encountered during the construction is classified as hard and strong rock by laboratory and field tests performed by the joint venture group. Within the scope of the study, for the prediction of the peak particle velocity and to determine the slope of the attenuation curves together with the maximum charge per delay for the S4 shaft tunnels and S12 shaft tunnels of this tunnel route, ground vibration components were measured carefully by using four vibration monitors (Instantel Minimate Plus model) during the advancement of the tunnels which required blasting. The particle velocities and frequency values of all blast events are evaluated according to the United States Bureau of Mines (USBM) and German DIN 4150 Norms in order to predict, and compare the influence grades to the neighbouring buildings, and structures. Also, data pairs of scaled distance and peak particle velocity obtained from 114 records at S4 shaft tunnels and 79 records at S12 shaft tunnels were analysed statistically. Empirical relationships with correlation at the 95 % confidence interval were established for different rock units (diabase and arkose) and suggested for the test sites in order to estimate particle velocity of the ground vibrations.

Jan 1, 2007

By Gordon M. Matheson, Douglas A. Anderson, David K. Miller

"Traditionally, analysis of vibrations from blasting has been focused on peak particle velocity fordetermining the likelihood of both annoyance and damage. The US Bureau of Mines, in RI 8507,indicated the importance of frequency in vibration. Methods of controlling the vibration by reducingthe vibration concentrated in certain frequency bands using delays have been successful over the past decade."

Jan 1, 1997

By Ola Lindahl, Mark Irving, John Hutchings

"Blasting is a process starting with a geometric description of the block of rock and ending with a pileof fragmented material. A key step in improving the productivity and quality control over the processis the integration of blast planning software, explosive delivery control systems, and blast recordingwithin one seamless customer solution."

Jan 1, 1997

By Tamara Whitaker, James Gunderson, Ruilin Yang

This paper presents the results of a vibration control project conducted in soft overburden at a surface coal mine located in the western United States. The study uses near-field blast vibration monitoring, analysis and modeling techniques developed in house. Accelerometer-equipped seismographs were utilized for near-field vibration monitoring and analysis. Vibration control was achieved through field data regression as well as vibration modeling using the multiple seed near-field blast vibration model (Yang and Scovira, 2007). The regression was conducted between peak particle vibration parameters and the minimum scaled distance per delay. From the regression analysis, the curves of upper bounds for peak particle vibration parameters and charge weight were developed. The dominant frequencies of the blast vibration were also addressed in this project. The regression curves and near-field vibration model guided the blast design to control blast vibration for maximizing the recovery of coal and maintaining mine productivity.

Jan 1, 2008

By Ron Frye, Carl Liibbe, Wayne Curtis, Julie Pecori, Dan Leach

Test work comparing the performance of a Low Density Porous Ammonium Nitrate Prill to regular Porous Ammonium Nitrate conducted in Pennsylvania and New York showed that less ammonium nitrate was required to perform the same work and that improved sensitization of an emulsion/ammonium nitrate blend reduced “orange fumes”. Fragmentation was similar in all tests with improved heave and throw experienced.

Jan 1, 1997

By Anthony J. Konya

"This paper was written during part of the author’s student co-op with Cargill Salt at its Avery Islandunderground salt mine in Louisiana. Blasting salt is a unique type of blasting that is different than blasting other rock types. The plastic nature of salt, along with its large swell factor make salt a challenge to blast. The Cargill salt mines use and have tested a variety of different methods for breaking salt in an efficient manner, however these blasting methods are rarely used in other operations nor talked about today."

Jan 1, 2016

By W. J. Birch, R. Farnfield

The use of electronic detonators to control blast vibrations has been previously established by many authors. This is performed by determining the optimum delay period between the blast holes for a particular pattern that can accurately control the firing frequency of the blast, which in turn has a direct bearing on the frequency composition of the ground vibrations recorded at a particular location. This was established by Pedgen, Birch, Hosein & Farnfield (2006) whereby like-for-like comparison tests between non-electric and electronic blasts were carried out in a limestone quarry in northern England. They demonstrated that resulting peak particle velocity values recorded at near and mid-field distances were primarily a product of the firing frequency of the electronically initiated blasts.

Jan 1, 2009

By Randall M. Wheeler

Using Computer software to analyze and interpret blast vibration effects has never been so practical. Fully digital seismographs and powerful desktop and portable computers have led to the development of fast and easy to use analysis software. This workshop will focus on new Microsoft Windows-based blast vibration analysis programs developed by White Industrial Seismology, Inc. The Windows point and click graphical environment is ideal for developing full-featured and yet intuitive software.

Jan 1, 1994

By Douglas Bartley, Brian Wingfield, Robert McClure

Recent studies and limited tests indicate favorable results utilizing high accuracy electronic detonator technology over conventional non-electric pyrotechnic systems. This study discusses the application of this technology using the Daveytronic programmable system in an on-going production basis. The study quantifies the performance as it relates to fragmentation, excavation, vibration and productivity in an eastern U.S. aggregate mining operation.

Jan 1, 2001