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By M. Araos

Non-ideal explosives can be characterised by different methods like velocity of detonation measurement, double pipe tests, underwater tests, aquarium tests, etc., to name a few. Both aquarium and velocity of detonation tests were selected to characterise a non-ideal explosive that is based on hydrogen peroxide, fuel, and void sensitisation. The detonation process in an aquarium of this sensitised explosive was captured at 80,000 frames per second using a high-speed camera. The explosive product was detonated using 51mm (2inches) diameter acrylic pipe charges. The product was detonated at different densities in an aquarium (cube box containing water). An aquarium provides a homogenous confinement for the detonation of explosives and more importantly, allows observing the shock wave as it changes the refraction index of water. The analysis of the video footage allowed the calculation of the velocity of detonation, pressure, gas rate release, and how the shock wave's shape in water changes with densities. It is suggested that the calculation of the rate of gas release could be related to the bubble data obtained from underwater tests.

Jan 1, 2024

By A. S. Tawadrous

Fines are produced in any blasting application. Depending on the application, fines may or may not be a desirable product of the blast. In most quarry and construction applications, fines are considered an undesirable product since it does not constitute a sellable product and there are costs to the operation for disposal. On the other hand, in most open pits fines do not represent as much of a problem since the ore has to be crushed and ground after being blasted. Therefore, fines in such operations may reduce the energy consumed in the downstream operations.

Jan 1, 2012

By Bruce B. Redpath, Doug Crice, Rob Huggins

Over the last decade, instrumentation has been developed that allows the application of seismic reflection methods to groundwater and engineering problems. At the Geological Survey of Canada, we have been developing and testing shallow reflection techniques for mapping the bedrock topography and structure within the overburden. We have attempted to develop methods which can be implemented with a minimum investment in equipment and computing capabilities. The data are recorded on a l&channel engineering seismograph, using a single high-frequency geophone per channel, and a hammer or in-hole shotgun (“Buffalo gun”) as the seismic source. Processing and display of the data can be accomplished on an Apple II+ or IIe microcomputer and an Epson wide-track dot-matrix printer.

Jan 1, 1991

By A. Torrance

A better understanding of the detonation performance of an explosive charge can be gained by directly measuring pressure, temperature and velocity of detonation (VOD). This is particularly important with commercial explosives because their performance is directly influenced by the degree of confinement given by the borehole diameter and the surrounding rock mass. A project funded by the Australian Coal Association Research Program (ACARP) was initiated in early 2009 with the view to design and build cost effective prototype instrumentation to measure the relative differences in detonation pressures and temperatures of commercial mining explosives. The project’s primary focus was on low density explosives. Low density (also referred to as low shock) explosives have been available in various forms for nearly 20 years. Identifying the pressure release patterns of both conventional and low density explosives under different geotechnical conditions should provide the necessary information to both validate detonation codes and better define input parameters for breakage and fragmentation models. This paper gives a general description of the prototype instrumentation developed and reports on the results obtained to date in testing the proposed instrumentation in laboratory scale conditions.

Jan 1, 2011

By Steve Dillingham

Here in the United States, as well as around the world, pose a daily dilemma - to wash or not to wash. Let’s face it, all trucks, especially our industry work horses - bulk trucks - get dirty. We all know that these units can be very expensive and washing them keeps your business investment looking new, improves public relations, fuels company pride, and facilitates equipment safety and preventative maintenance inspections.

Jan 1, 2001

By N. Rouse

Underground raises and slots are a vital part of underground blasting operations. Raises and slots are vertical shafts or openings used for ventilation, ore passes, or creating voids in stopes. In the author’s experience, raise and slot designs can vary significantly from operation to operation or even within a single operation, sometimes for reasons unknown. The results of the various designs can differ depending on drilling accuracy, geology, and the explosives used in the design. The purpose of this paper is to summarize the recommendations found in published literature on raise and slot design in one document, while incorporating some of the author’s own experience with optimizing raise and slot designs in underground operations. Some inspiration is also included from burn round designs; small versions of raises drilled horizontally in development blasting rounds. This document includes discussion points on drillhole diameter and depth, pattern design and relief requirements, explosive types and loading recommendations, and timing. Ultimately, this document can be useful to those looking to design a raise or slot blast for the first time or for those looking to improve on the results from the raise and slot blasts used at their operations.

Jan 1, 2024

By C E. Johnson, S Hosein

Previous researchers have put forward two different theories as to the origin of air overpressure from quarry blasting. In 1980, Siskind et al postulated that the initial face movement gave rise to the displacement of air and that this resulted in the air overpressure pulse. However in 1990 McKenzie et al carried out research that indicated that the air overpressure pulse came into being as a consequence of the shock wave created by the detention of the explosive charge in a blast hole. In an attempt to evaluate these hypotheses, an investigation was undertaken over a 4-year period with the aim of determining the precise origin of air overpressure. The research was carried out at a chalk quarry in the North of England.

Jan 1, 2017

By Jorge Cárdenas, Piero Mejía, Diego Gamarra

The present case study details the solution to a complex situation in a mining operation, involving the challenge of expanding the tailings storage facility in high-criticality areas adjacent to electrical rooms that provide continuous power to the entire mining process, including water pumping and drainage systems. For this purpose, blasting is required to prepare the construction areas for the new expansion facilities. Upon deciding to proceed with blasting, a comprehensive engineering assessment was conducted to ensure operational continuity without impacting the process, while generating sufficient fracturing in the rock mass to allow extraction with auxiliary equipment. Support from specialists through the Technical Assistance area was requested, and a detailed evaluation was carried out through advanced studies. Field vibration studies were conducted to define attenuation models and characterize the rock mass in the sector. With this information, simulations were carried out using predictive and probabilistic models with Monte Carlo methods to select delay charges and optimal timing for reducing vibration levels and increasing frequency levels. With these measures, the three blasts conducted near the Gas Insulated Substation room, which had distances ranging from 30 to 100 meters, produced the following results: • Vibrations; The three blasts conducted at distances of 100, 30, and 50 meters recorded vibration values of 5.3, 40.2, and 9.5 mm/s, all of which were below the maximum vibration level of 50 mm/s set by the projects area. According to the USBM RI8507-OSMRE standard, all values for Peak Particle Velocity (PPV) and frequency were below the permissible limits. • Flyrock; Through filming and post-blast inspection, it was confirmed that the ejections were within the safety zone. • Fragmentation; The results obtained showed a maximum overbreak size of 1.5 meters, allowing the broken material to be moved effectively.

Jan 21, 2025

By S B. Richardson, D Mead, N T. Moxon

The use of air-decks to reduce explosive costs has become very topical in recent years. The majority of the research in this area has been arried out between the Soviet Union where reductions in explosive consumption of between 10-30% have been claimed with apparent benefits being gained in both fragmentation and movement. Work carried out by the University of Maryland using thick plexiglass blocks has supported these findings and indicated that air-decks in measetbe duration of action of the shock wave on the surrounding material by a factor of 2 to 5 (see Figure 1). Although the fracture network resulting from this mechanism is not as intense as that produced adjacent to the explosive charge it does appear to act over a larger volume of material. Although the mechanism attributed to air-decking has been studied in some detail the effect of this mechanism on the size distribution of material produced during a blast does not appear tot have attracted much attention.

Jan 1, 1991

By Nikolaos Petropoulos, Ulf Nyberg, Ulf Stenman, 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.

Feb 1, 2020

By John C. Brulia

The IME member companies, the ISEE along with its chapter organizations, the Federal, state and municipal regulatory agencies, and the industry consultants and suppliers have developed safety equipment, provided safety guidelines, promulgated safety-oriented regulations, and conducted safety training for blasting personnel in an effort to reduce explosives-related accidents.

Jan 1, 1994

By K. Best, D. Conn

The US Army Corps of Engineers KY Lock Project in western Kentucky presented the blasters and vibration consultants with a set of unique challenges. The blasters on this project were faced with difficult geology and joint set orientation and sequencing of blasts opposite from what the explosive engineer/blasting specialist had recommended. Combining these issues with strict vibration and air overpressure specifications, blasting as close as 7 feet (2.1 meters) from a new lock wall, site topography that influenced the air overpressure, limitations on seismograph geophone placement that led to anomalies in seismograph recordings; surprising lessons were learned by everyone involved in the project and it is the authors’ goal to share this valuable information with everyone in the blasting industry.

Jan 1, 2024

By Manuel Villalobos Calderón

This paper presents the Enaex group approach to addressing the blasting challenges and outlines the solutions created. Aspects such as rock mass damage occurrence as a function of blast vibration frequency content has been studied, as well as the development of blasting methodologies for guaranteeing the full 100% extraction of all infrastructure blasts, including the all-important drawbell volumes. The development of such infrastructure volumes in one single event using electronic detonators and the associated achievement of ambitious productivity goals, are described as a critical part of the successful construction of one of the most ambitious UG projects currently present on the world.

Feb 1, 2020

By Manuel Calderón

Chile is responsible for 30% of the global copper production; the world ́s largest. However, significant challenges are faced in this industry; declining grades (1.13% in 2002 to 0.61% in 2015), high cost of energy, scarcity of water, and environmental concerns. Mining trends suggest the future of the industry will be focused in the underground space, specifically due to the depletion of economically viable surface mineral deposits. For example, the largest block cave mineat Codelco ́s Chuquicamata mine is expected to reduce energy costs by 50% and dust emissions by 97%compared to the open cut mine. To access these underground deposits, critical infrastructure is required; horizontal tunnel developments, extraction levels, vertical raises, and ore passes with the on-time delivery of the highest quality outcomes being a requisite for successful project delivery (Lift 1 of 3 at Chuquicamata Underground has over 1000drawbells).One aspect that makes this scenario even more challenging for deeper underground operations is the increased risk profile (people, equipment, and geotechnical) that forms part of the general environment. Furthermore geotechnical risks should be considered and they include rock burst and windblast. The safe interaction with this environment must be sustainable throughout the full life of the project. This paper presents the Enaex group approach to addressing the blasting challenges and outlines the solutions created. Aspects such as rock mass damage occurrence as a function of blast vibration frequency content has been studied, as well as the development of blasting methodologies for guaranteeing the full 100% extraction of all infrastructure blasts, including the all-important draw bell volumes. The development of such infrastructure volumes in one single event using electronic detonators and the associated achievement of ambitious productivity goals, are described as a critical part of the successful construction of one of the most ambitious UG projects currently present on the world.

By Pavel A. Torres, Darwin Torres, Sandro Huaman

Given the limited efficiency of blast-induced ground vibrations prediction empirical models, due to the complex geological system from a Peruvian mine. An artificial neural network was built in order to get better results. More accurate and precise predictions allowed the generation of blasting domains for future designs and decision making.

Feb 1, 2020

By Paulo Couceiro, Juan Navarro

The impact of rock blasting fragmentation and heave on digging performance in open-pit mining operations is usually the first true indicator of blasting outcomes. Within the typical excavation cycle, the bucket loading time or instantaneous digging rate are the ones that present the strongest correlation with rock fragmentation size distribution, swelling, and shape of the muckpile, a part of rock mass hardness, equipment size, power, and others. As the efficiency of unit operations becomes increasingly important for long-term mining strategies, cost-effective approaches are needed to increase mine productivity. In this line, the performance of downstream operations, such as digging, hauling, and comminution, may be affected by the energy input in blasting. This requires a better understanding of the explosive’s energy role in such unit operations in order to drive consistent improvements. Therefore, this paper examines the impact of the explosive’s energy distribution on shovel diggability from production shots carried out with different explosives in an open pit gold mine, with the aim of modelling the interface between blasting and excavation.

Jan 21, 2025

By Daniel Richards, Dr Rob Farnfield, Dr Geoff Adderley

The 8-millisecond rule has been in use for many years as a basic technique to help minimize vibration levels from surface blasting operations. The rule was based on work carried out in the 1960’s by the USBM by recording the vibration levels from a series of test blasts in a quarry over a range of distances. This work included the firing of a series of single hole blasts and a number of single row production blasts using a variety of inter-hole delay times. The delay times employed were limited by the technology available at that time to instantaneous, 9, 17 and 34 milliseconds. There have been several papers in recent years suggesting that the use of the 8-millisecond rule is no longer required, when using electronic detonators, due to their enhanced accuracy and greater initiation pattern design flexibility. This paper examines this proposition by revisiting the original work and employing the linear superposition technique to reprocess some of the original recordings. Similar techniques are then applied to a large database of single hole vibration recordings for a range of rock types, distances, and number of decks, with calculated reinforcements compared to the minimum separations in typical patterns. The results suggest that there is some validity to the 8-millisecond rule when applied to electronic detonators but not in the way it is traditionally applied. Simple guidance is suggested for those designing blasts with electronic detonators to minimize vibration levels even if the benefits of linear superposition trials are not available.

Jan 21, 2025

By Harry Verakis, Thomas Lobb

Blasting accident data over a 30-year period (1980-2010) are summarized and presented for all types of surface and underground mining operations in the USA. The historical record of injuries from blasting accidents in all types of mines continues to show a significant decline. The overall decline in mine blasting injuries in the U.S.A. has resulted from advancements in blasting technology, training and improvements in blasting products and blasting processes. Some of the technology advancements such as safer blasting agents and computerized bulk vehicle loading, electronic detonators and remote operated blasting systems, and computerized blast design have and continue to significantly contribute to improvements in the historical blasting safety record. Also, the progress of significantly improving the safety of mine blasting has resulted from the combined efforts of miners, mine companies and operators, miners, unions, explosive and blasting product manufacturers, associations such as the International Society of Explosives Engineers and the Institute of Makers of Explosives and various government agencies.

Jan 1, 2012

By Shazad Hosein, William J. Birch, Robert Farnfield, David Jameson, Catherine E. Johnson

The current and consented quarry workings at a slate quarry in North Wales {UK} intersect old long abandoned underground slate mine workings. The old underground slate mine contains the remains of World War II buildings used to house artworks to protect them from war damage. Over the past 20 years, there have been a number of roof falls in the old underground slate mine, which have damaged the buildings and make general access unsafe. From observation of the timing of these falls, they occurred in the mid 2000’s. The purpose of the exercise was to determine the possible relationship between blast vibrations experienced on the surface and those experienced on the roof of the abandoned mine caverns. Thus preventing the need to regularly monitor in the old mine workings. In order to achieve this, a rigorous geotechnical assessment of the stability of the caverns was undertaken by a fully qualified Geotechnical Engineer. Once it had been determined that it was safe to do so, 3 “MEMs based” blasting seismographs were attached to the roof, in accordance with the instruction of the geotechnical engineer. In addition, 8 “MEMs based” blasting seismographs were deployed at various locations on the surface. The trial blast comprised of 51 blastholes, with charges varying between 46kg [101lbs] and 124kg [273lbs] of bulk emulsion explosive. The blastholes were in 4 rows of holes. The blast was connected using shock tube 25ms, 33ms and 65ms delay period relay detonators. The minimum distances from the blast to the surface and underground monitoring points were 78.1m [256 ft] and 114 m [374 ft] respectively. The results from the three underground monitoring locations in terms of resultant peak particle velocity was 4.42 mm/s [0.174in/s], 3.47 mm/s [0.137in/s], and 4.69 mm/s [0.185in/s]. In line with previous research, it was determined that the underground results [when compared on a “like for like” basis in terms of scaled distance] were lower in amplitude than the surface results. In this case by a factor between 0.47 and 0.87, averaging 0.68.

Jan 21, 2025

By C. Liley

Open cut blasting at the Ernest Henry mine has the potential to cause damage to nearby underground workings. This paper is a case study of the blast vibration management project which was conducted to ensure pit blasting did not adversely affect the stability of upper production levels or cause damage to the underground primary fan units.

Jan 1, 2012