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By Ruilin Yang

Blast vibration in the highwall from a cast blast in open pit mines or in the hanging walls from a stope blast in underground mines is a common concern. Vibration in such cases is a typical near-field situation where the distance from a blasthole to a point of interest varies significantly compared to the distance between the blast as a whole and the point of interest. Most existing blast vibration models are designed for far-field vibration using a single seed wave to represent all blastholes within a blast and do not simulate wave shape change over the distance. Using the site parameters from the analysis of signature hole vibrations, the present blast vibration model yields reasonable agreement with field measurements in terms of vibration amplitude and frequency. Case studies show that the model has been used successfully to assist field vibration control.

Jan 1, 2010

By Enver Alan, MerkeziYapı

People are migrating because of economic, social, natural and political reasons. These natural and humane factors effects the distribution of populations. The need for tunnels has grown in order to provide a comfortable life and reduce losses such as waste of time, labor, energy, efficiency and so on. It is inevitable to carry out excavations in rock tunnels (shears, platforms, lines, connections, wastewater, distribution, energy, transportation etc.), that will be built by excavating with conventional method, by controlled blasting regarding with constrains. In this study of applied explosives engineering the blasting applications are evaluated, which were carried out for research and development purposes at Yenisahra Station tunnels in Kartal Formation which was built with the aim of solving İstanbul's transportation problem within the framework of the Kadıköy-Kartal Metro Project. Twenty-four shots were made by using explosives in 60 blastholes that were drilled in the tunnel faces, which were located between and outside of two different faults. Six microphones were used to measure the air shock and eight geophones were used to measure the parameter values of the vibrations (particle velocity, frequency, displacement, acceleration, amplitude, wavelength etc.), which were placed at predetermined points of the surface, occurred during the blasting applications. Data from the geophone and microphones were recorded on six seismographs. The coordinates and the distances between the shot points and the measurement stations are determined by an electronic theodolite. The total number of seismic records, recorded in seismographs, is 118. The number of records of vibrations that crossed the faults is 42 and the number of records of vibrations that did not cross the fault is 76. The particle velocity, frequency, amplitude, acceleration, displacement and wavelength were measured in transverse, longitudinal and vertical directions. The total number of measurements is 354. By evaluating all seismic records, the effect of delay intervals, faults and scaled distances on the particle velocity, frequency, amplitude, displacement, acceleration, wavelength and air shock were investigated. When the vibrations formed during the Research & Development (R&D) blasts were examined, it was determined that the parameter values of vibrations that crossed the faults are lower than the ones that did not cross the faults. In addition, when the particle velocity values of all vibrations are examined according to the present circumstances, it is determined that the waves did not cross the fault in all delay intervals are superposed in all directions, and that the least superposing occurred in the 50 ms delay range.

By Ron Stewart, Richard Youmaran, Andy Adler

In the current context of heightened concerns with explosives security, there is significant interest in technological controls to improve security. It is important to be able to control what is fired, by whom, where and when. This paper describes research Orica has performed to investigate and test biometric systems to address the question of "by whom". The goal of this research is to incorporate the most suitable biometric system onto the 'blaster' unit of an electronic initiation system. This approach will ensure that only authorized personnel can initiate a blast involving electronic detonators. Requirements analysis: we initially explored many different biometric technologies to evaluate them against the requirements, including security, usability, ruggedness, size, form factor, privacy, and operational temperature range, This analysis identified chip based fingerprint sensors as the best candidate. Development of prototype units: in order to test the identified sensors, we modified standard, commercially-available, electronic blast initiation units ("blaster") to incorporate a fingerprint reader. Testing and evaluation: Biometric We conducted a biometric scenario evaluation in order to determine: 1) security level (measured by false accept rate (FAR)); 2) usability (measured by failure to enroll (FTE) and false reject rates (FRR)), and to 3) discover environment specific issues and challenges (such as temperature, humidity, dirt, or those related to the usage patterns of the user group). Tests were conducted at quarry sites in eastern Ontario, Canada. Results show rates of: FAR= 0%, FTE= 1.67%, FRR= 28.81%. Overall, these results suggest that this fingerprint biometric technology has a good level of usability in this application of electronic blast initiation control.

Jan 1, 2007

I had the opportunity recently to visit a magazine site of a major explosives company. It was fun to see the storage areas again and it was really interesting to see one of the old magazines that probably dated back before my time. Now that’s an old one. As son Tom says, “When Dad was young the Dead Sea was just sick.” While the magazine has been upgraded with a modern lock to match today’s standards it still has the old tumbler lock that is opened with the large bronze key. Those old tumbler locks were just about standard on magazines years ago. Those bronze keys were heavy and would make a good display item today or maybe a substitute for a blackjack. I don’t think the old locks would stop the modern criminal but then in those days we were all less sophisticated. And maybe I shouldn’t say this but honesty was a bit more prevalent then. Maybe ‘cause old fashioned police brutality still prevailed.

Jan 1, 2004

By Robert Hopler

DESCENT INTO A COAL MINE From “The Playbook of Metals, including Personal Narratives of Visits to Coal, Lead, Copper, and Tin Mines,” by John Henry Pepper. Published by Routledge, Wa rne, and Routledge, London, 1862 ENGINEERING NEWS New Yor k January 22, 1903 THE BEGINNING OF THE END OF DYNAMITE. In another part of this issue we have reported the results of some test results made upon one of the safety powders. It will pay every c o n t r a c t o r, miner, or user of explosives in any form to carefully re a d the article re f e r red to. Dynamite has done a gre a t work in the service of man, as did black powder before it; but its i n h e rent dangers are admitted by all and are proved by the long list of deaths and injuries, and destruction to property which annually occur through its use. Why should we continue to use an explosive that annually kills and maims hund reds of men, when others are available which are equally powerful, no more expensive and far less liable to accidental discharg e ? Dynamite when first manufacture d is pure and comparatively safe; but most unfortunately it does not always stay pure; it “rots,” and then it is exceedingly dangerous. More than this, the explosive part of dynamite is a liquid, nitro - g l y c e rine, which is absorbed or soaked up by sawdust, wood pulp or the like. So long as this liquid nitro - glycerine remains pure and remains “soaked up,” or absorbed t h e re is little danger. It has been found, however, that the nitro - g l y cerine leaks under certain conditions. During thawing it fre q u e n t l y leaks out of the stick, or if it becomes wet the water causes the n i t ro-glycerine to leak out. In either case free liquid nitro - g l y c e r i n e escapes, and in that free state it may be exploded by any very slight shock. Nor is this all, if a stick of frozen dynamite be bro k e n a c ross it has been found by tests that the frozen nitro - g l y c e r i n e w h e re thus broken is very sensitive to shocks afterward .

Jan 1, 2004

By B. Papillon

There has been a veritable increase in the adoption of electronic detonators in the last few years. Electronic detonators offer several distinctive features over electric and non-el (shock tube) detonators including better timing accuracy resulting in excellent fragmentation and vibration control, certainly key mining parameters. The field programmability also helps in reducing the on-site magazine storage of detonators with diverse fixed delays. A typical electronic detonator may consist of a logic core, a communication interface, storage capacitor(s) and the ignition element. Being electronic components, the electronic detonators may be susceptible to RF or electromagnetic interference (EMI). RF sources are virtually everywhere: cellular phones/towers, radio transmission, microwaves, walkie-talkies, high voltage (HV) transmission cables and wireless networks with their characteristic frequency emissions. Safety issues prevail; e.g., whether the RF interference can cause premature or inadvertent firing whether directly or indirectly. From a reliability perspective, the RF interference may also impact on bus communications, e.g., during the logging, verifying, charging and firing phases. The deleterious communications disturbance may result in a misfire (non-firing of one or more of the detonators) which is terribly inconvenient for the mine operators and even pose a safety hazard.

Jan 1, 2009

By Ed Billington, Mike Shields

The trail blaster is faced with a wide range of workrelated challenges, not the least being the work setting itself. It is usually remote, being anywhere from 5 to 30 or more miles (8 to 50 km) from any road. It may be in mountains, high rock desert, or coastal rain forest, and can range from sea level to over 12,000 feet (3700 m) in elevation. The blaster may be part of a 2-person clearing crew, a 4-person maintenance crew, or a 10-person construction crew. The crew will usually be mobile, moving and working up to 10 miles (16 km) or more per day, relying mostly on their own backpacks to move camp, tools and supplies from site to site. Periodic resupply may be by helicopter, aird rop, or even “sherpa” groups, but most often will be by packstrings of horses and mules. The crew goes into the backcountry a n y w h e re from two weeks to three months at a time, and while there, its members “live the job” 24 hours a day, enjoying baking heat, torrential rain or mid-July s n o w s t o rms along with the truly glorious weather that c o m p e n s a t e s . So who is this blaster? Well, “he” may be she, since some of the top trail blasters are women. He/she will also be more than a blaster: Crews are small, so experienced members must be capable of handling the full range of trail work. Thus this blaster is also a driller, and usually also a bucker, snag faller, rigger, dry-stone mason, log and timber carpenter, bridge builder, mule p a c k e r, small-engine mechanic and, not least, camp cook capable of putting out a hot meal from a campfire , in a downpour, in the dark. Being in remote locations, often without reliable communication to the outside world, trail crews enjoy a remarkable degree of independence from “supervision.” With that comes the responsibility to make sound decisions which expedite the work, while promoting crew safety and welfare .

Jan 1, 2004

By Peter Moser, Mark Ganster, Andreas Gaich

Surveying of a bench face before blasting is a pre-requisite for a proper blast planning and for a satisfying blasting result both in terms of safety and fragmentation. When surveying a bench face, preferably a large amount of measurement points are required in order to determine the geometry and especially the irregularities with sufficient accuracy. Only contact-free measuring systems allow evenly distributed measurements over the whole bench surface. Existing systems such as total station, laser profiler, or laser scanner show significant drawbacks such as that surveying results are just isolated values of the bench geometry such as heights or profiles, that borehole positions have to be defined in advance in order to know where to take profile measurements and that systems require special surveying skills and that they are expensive too. In order to overcome these difficulties and to provide the blasters a simple tool for bench surveying, blast design and layout and the subsequent back-transfer of the blast plan into the quarry, the Department of Mineral Resources& Petroleum Engineering of the University of Leoben, 3G Software & Measurement company and Mineral AB, one of the largest producers of aggregates in Europe formed a joint venture to develop a new system. Based on an existing stereophotogrammetric system for rock surface surveying and joint analysis (JointMetrix), a new tool was developed within a year. Apart from several mines and quarries using that new tool already today in the daily work, both the Department of Mineral Resources& Petroleum Engineering at the University of Leoben and Austin Powder GmbH Blasting Service did a lot of studies to determine the reliability of the new stereophotogrammetric blast surveying and planning system and its precision in comparison to classical laser surveying equipment. After 1 year of testing and comparison with laser based surveying instruments, it can be concluded, that the new technology of blast surveying& design systems based on stereophotogrammetry is suitable for being used in the daily work routine in quarries and mines. The comparison of the precision of laser based systems and stereophotogrammetric systems has shown, that the deviation between these two types of systems is less than 10 cm, in many cases even lower.

Jan 1, 2007

By Robert Lee, Jeff Corace, Rob Cyr

Blasting in the heart of the historic Byward Market District of Canada’s capital, Ottawa, presents a unique set of challenges. The obvious difficulties arising on projects requiring blasting within 3 m (10 ft) of 125 year old buildings in various states of disrepair have been encountered and successfully dealt with countless times before. The complexities increase exponentially when tenuous property boundaries, unknown structural details, litigious histories and the need for encroachment agreements lead to individuals with competing interests all able to impact the same operation. Blasting on three projects in the Market was started in early 2005 after months of negotiation. Ultimately, the potential for the projects to proceed hinged on the ability to successfully disseminate blast data to the various stakeholders. As part of the agreements drawn up, property owners demanded immediate notification of the measured vibration levels with contract provisions including clauses such that any exceedance of the USBM criteria immediately triggered project shut down and complete blasting program redesign, and approval by all parties. With stakeholders located in various cities and, in some instances, on various continents, a conventional attended monitoring strategy would not satisfy the requirements. In response to the critical reporting need, Explotech Engineering Ltd. installed unattended monitoring stations around the sites, all incorporating wireless telemetry. After each blast, data was automatically transferred from the monitoring stations to a web-linked server via the wireless network, where it was immediately available to project stakeholders through a password protected website. The solution required a unique blend of data acquisition, telemetry, database, and security technologies, all married to produce a reliable system that was easy to maintain and use. While these types of systems were originally developed for use as permanent monitoring networks in operating mines and quarries, monitoring professionals are increasingly benefiting from the technology on temporary building projects that have typically been the realm of attended monitoring strategies. Globally, this has emerged as a solution to provide more timely access to data for stakeholders, and to minimize the legal exposure from multiple violations of vibration limits. As this trend is likely to continue, the regulated vibration control industry is likely to see a continued shift in technology development to leverage wireless networks and the Internet to continue to improve data transfer, archiving and distribution.

Jan 1, 2006

By N. Powell, P. Hunt, A. Wetherelt

This paper considers the current methods of analysis employed, the validity of assumptions made and the reliability of results and predictions derived; where appropriate, alternative methods are proposed which are more accurate and can be applied with greater confidence. In regard to data collection, new local blasting data has been analysed and conclusions drawn but, due to the restricted amount of space available, reference to data set A only has been made in the text. The problem of mathematical model choice is considered and results for two and three parameter power laws are compared. The very important matter of parameter determination is discussed fully, with major emphasis being placed on the comparative merits of log-log linear, log-log planar and direct power law regression. Supporting data analysis examples are included. Assumptions regarding the normality of ‘best-fit’ regression model residual distributions are questioned and the reliability of associated safety limit determinations is discussed.

Jan 1, 2003

By Chen Jianping, Wu Li, Wei Banyun, Chen Canchang

Liquified petroleum gas mixed with oxygen has been used as a new type of mixed gas source for gas detonating system. The experimental studies have been done on the detonation feature of gas detonating transmission in a long and thin tube, the transmitting reliability for detonating network, the design on gas exploder and test devices. The results of the study show that (1 )Liquified petroleum mixed with oxygen can be used as a new type of regular gas source. (2)The transmission of detonating wave is reliable for new type of mixed gas in a 500-meter long plastic tube with 3mm inner diameter and the detonating velocity is up to 2500m/s. The detonating wave can surely initiate and transmit several branched gas detonating cap and explosive through the end of detonating network, the tubes inner diameter for the detonating quenching is 0. I’mm. (3)The gas exploder designed by authors can be used for gas propotional distribution,strong turbulence-mixing,initiating by reflex shock wave and safety control purposes. The developed double flowmeter can be used together or seperately in responsible for main testing in the system.

Jan 1, 1999

By A T. Spathis

The 11th International Symposium on Rock Fragmentation by Blasting (FRAGBLAST 11) was held in Sydney, Australia, between 24-26 August, 2015. The 93 papers, including six keynote presentations, covered exciting and practical topics in 20 sessions within 12 themes. Just fewer than 300 delegates from 27 countries attended. Four workshops were conducted on the weekend prior to the symposium, with three field visits after the symposium to Sydney region quarries, the Hunter Valley coal mining region, and the Kalgoorlie gold mining region. Delegates had the opportunity to visit the exhibition areas that showcased the latest products, software, hardware and systems in blasting technology. The keynote addresses were held in plenary sessions and set the tone for the parallel sessions that followed. They spanned the dynamics of the mining industry, the detonics of explosives, the interaction of stress waves and fracture mechanics in fragmentation, wall control blasting, and the importance of education and engineering for full process optimisation.

Jan 1, 2015

By Santiago Gómez, Pablo Segarra, José A. Sanchidrián

In-hole detonation pressure measurements are unusual in the production environment of a mining operation, partly owing to the hostile conditions to which recording equipment and pertinent probes must be subjected and, partly by the constraints of the production cycle. In recent decades, detonation pressure measurement techniques have been developed using low carbon resistors (LCR)-based gauges. They are cheap, relatively easy-to-operate, robust and with a high percentage of success in both open-pit and underground mining. Detonation pressure measurements are extremely important when carrying out numerical modelling to simulate explosive induced vibrations, since simulation results are highly dependent on the pressure-time history applied on the blasthole wall. Analytical equations have typically been used to model the pressure-time history; however, they usually do not adequately represent the behaviour of the explosive in terms of: peak pressure reached, rise time, mean frequency, decay and shape of the signal. Experimental records may be directly used instead of utilizing synthetic signals if they are available. In this work, (LCR)-based gauges are used to measure detonation pressure inside a production blasthole. The operation principle of the gauges utilized and the instrumentation layout is described in detail. A flexible resolution USB oscilloscope with high sampling rate has been used to catch the elusive pressure peak event. Measurements were carried out in production blasts fired with ANFO (0.86 g/cm3) in an underground mine––this also includes velocity of detonation (VOD) records––. A procedure based on the shock impedance matching has been developed to calculate the detonation pressure due to the characteristics of the gauges prevent its direct measurement. Detonation pressures obtained range from 1.71 to 2.97 GPa (248.01 to 430.76 ksi) which are in line with pressures calculated from the VOD records. Mean frequency and rise time analysis shows that 2 of 3 signals cannot be described using typical analytical equations.

Feb 6, 2023

By David G. Borg

"Although researchers have realized varying degrees of success in numerics modeling, computer blast simulations and small scale in-situ testing, most will agree that the greatest uncertainty in total success stems from the uncontrollable field variables. Given the diverse nature of field conditiorencountered, no reliable and proven method of evaluating fragmentation quantitatively, and the lack of adequate field controls found in many operations, it is unlikely that a universal plug-in model will be developed for all blasting in the imediate future. This does not imply that all research devoted to modeling should cease, for it is precisely here where more research efforts are desperately needed."

Jan 1, 1989

By R. F. Favreau, Patrice Favreau

In many quarries and construction sites visited by the authors over the last 50 years, the latter have observed muck piles from blasting with explosives, which included numerous large blocks, in some cases of dimensions larger than the input to the crusher. The names of these sites cannot be given in the article because the owners insist that data obtained on such visits be kept confidential. Often the blasters felt that the natural fissures in the rock would compensate for the use of a low powder factor, and they asked the authors to explain why such blocks were present. A detailed analysis of the situation often indicated that the cause of the blocks is that explained by figures such as 6 and 7 below in the article.

Jan 1, 2018

By Rachel Bauer, Jacob Henderson, Dr. Catherine Johnson

Capital Quarries in Owensville, Missouri faces several challenges when designing a blast that allows for ease of movement while maintaining controlled throw and compliant air over pressure. The primary challenge is the nearest non-owned structure (NNOS) is a residential home located 250 feet from the quarry. Another challenge is a production bench which is 100 feet tall and separated from the NNOS by Pennsylvanian fire clay that filters out high frequency waves from the blast. Material from the blast must also be less than 5 inches in order to be processed by the crusher in the quarry. To provide as much relief as possible, production shots will consist of a single row with the minimum required burden. To design the shot, signature hole analysis was used to determine the optimal timing between powder columns. Electronic detonators provided an accurately timed shot to minimize the amplitude of the vibrations while maximizing the frequencies. Boretraking and 3D profiling with Renishaw laser profiler and Strayos drone photogrammetry provided an accurate burden measurement. Powder factor was kept at 1.3 tons/lb using bulk emulsion. The boreholes were split into 5 powder columns with the top of the hole firing first in order to blast to floor grade. The resulting shot produced good fragmentation and shot to floor grade. Seismograph readings showed air over pressure vibrations within legal limits. Due to this success, multiple shots will be designed using the process described.

Feb 6, 2023

By John H. Weigand, Stephen V. Crum

"VIBRONICS, INC. instrumented and monitored a residential structure for response to,blasting at aMidwestern surface coal operation. The residence was owned by the mining company and was extremely close to the operation. Blasting was conducted within 120 feet (36.5 meters) of the test structure. Up to seventeen (17), four (4)-channel seismographs were used during the monitoring period. The basement walls and floor were monitored. VIBRONICS, INC. also monitored a brick chimney in the basement and attic. Structural responses were then compared to outside vibration measurements taken in the soil near the foundation."

Jan 1, 1998

By Steve Dillingham

In every aspect of conduct, on the blast site or off, the issue of credibility is raised. Promises are made, commitments are satisfied, safe practices are obeyed, communication is maintained, and proven procedures followed. Only by fulfilling these objectives, are we deemed trustworthy and reliable - in other words - credible. Unfortunately, at times, we fall short of achieving our goals. Whether intentionally or accidentally, everything is not completed according to plan or accuracy. On the blast site, falling short of achieving such goals may contribute significantly to a chain of events that can potentially produce accidents. At the very least, a blaster’s credibility will be jeopardized. The fact remains that the blaster that continuously conducts business in a professional manner will less likely find him or herself as a defendant in future claims.

Jan 1, 2003

By Riaan Van Wyk, Gys Landman

In today’s mining environment the use of radio communications in the form of two-way radios, cellular phones and even automated mining, form a vital part of the daily operations of a mining site. The radio transmissions that are used are a form of energy and as with all other types of energy it can have an influence on blasting equipment.

Jan 1, 2011

By Steve Dillingham

Whenever misfired holes or portions of misfired holes remain after a blast is fired, a hazardous situation exists until the unfired explosive materials have been disposed of properly. Yet, there are so many factors that can contribute to misfires that it is impossible to give blanket instructions on how to handle them. To complicate matters, misfires today are rare due to reliable blasting products. As such, it isn’t very surprising that many blasters have never had to deal with a misf i re condition. While the likelihood of a misfire occurrence is minimal, you should always be pre p a red to handle a misfire should you be involved in such an event. To begin, every blaster and blasting org a n i z a t i o n should develop a misfire policy which contains the company’s safe operating pro c e d u res, emergency contact list, as well as any regulatory compliance re q u i re m e n t s . Tailgate and/or company-wide safety meetings should communicate the company’s contingent misfire pro c ed u res and any special site-specific precautions BEFORE the start of any project.

Jan 1, 2004