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By Stephen John Brace

Increasingly, electronic blast initiation systems are being made available to the mining and construction community, both in South Africa and internationally. Indeed, in some parts of the world, perhaps half a dozen electronic products are being used, with a choice also of shock tube, electric and fuse and igniter cord systems. As these developments have taken place, improvements have been made in safety, reliability and accuracy, so much so that high performances in all these areas are now expected. However, disadvantages often seen by customers, other than : higher price, are decreased user-friendliness and loss of flexibility.

Jan 1, 1998

By Minoru Kawamura, Shinya Tanaka

In Japan, a cartridged emulsion explosive is generally used for tunneling. The workers are compelled to approach the face on charging the explosives into the drill hole with the tamping rod. Therefore, the workers are exposed to the risk of the disaster with the cave-in and the falling rock. The mechanization of the tunnel work has been advancing gradually. Especially, the development of the mechanization for charging work is desired in order to avoid the risk of disaster on workers. Recently, some charging machines such as the bulk emulsion explosives have been evaluated. However, a universal method has not been established yet, because the evaluated machines were not adequately suited from the point of the regulations and the consumption style of explosives.

Jan 1, 2008

By Martin Langenderfer, Catherine Johnson, Phillip Mulligan, Kelly Williams

The physical geometry of a charge has a direct correlation to the geometry of the shock wave. This relationship appears strongest within the boundaries of the visible fireball. As the shock wave propagates outward past the limits of the fireball, the theory states that the geometry of the shock wave should even out and become more spherical. This paper investigates pressure vs. time at two distances, one ‘Near Field’ at the extent of the fireball and one ‘Far Field.' The two Fields were instrumented with three free-Field pressure probes from PCB oriented at 0, 45, and 90 degrees to the front face of the charge, in the same horizontal plane as the charge. This orientation allows for the comparison of the shock wave from the face and vertices of the charge. All the pressure sensors were connected to a Data Acquisition System (DAS) recording at 2 million samples per second (2MS/s). Two high-speed cameras, a Phantom and an MREL Ranger II, recorded the detonations for qualitative examination of the fireball, and the shock wave. Three charge geometries were used and compared to the shock propagation of a sphere. The other geometries tested are cylinders, cubes, and tetrahedrons. Charges were made from a PETN based sheet explosive. In the Near Field, a lower pressure is observed along charge vertices with highest pressures from each face. In the Far Field, vertices record a higher pressure, possibly due to the shock waves from the adjacent faces intersecting, indicating that shock pressures do not always even out in the Far Field. This paper will describe the methodology and findings of this experiment and attempt to determine causality for trends in the data gathered.

Jan 1, 2018

By Lawrence W. Gubbe

Air blast associated with detonation of explosives in mining, construction or military applications is often responsible for complaints by people who live or work in the vicinity of the activity. Most often, the complaints are based on the perception that vibration caused by the airblast damaged one or more residential buildings that may be located within several hundred feet or several miles from the blast site. The potential for airblast to cause damage is related to the amplitude and frequency of the airblast overpressure wave at the receptor. Amplitude and frequency of the overpressure wave are, in turn, dependent upon the type and amount of explosive detonated; the degree of confinement; the distance the wave travels; the topography between the blast site and the receptor; and, atmospheric conditions. It is well known that, as the result of atmospheric focusing, the amplitude of airblast overpressure that exists relatively far from the blast site may be substantially higher than the amplitude associated with the attenuated wave in an isotropic atmosphere. Two methods are available to predict baseline overpressures 1) the Sandia Laboratories, Atomic Energy Commission method as extended by the Naval Ordinance Laboratory (NOL method) and the Ballistic Research Laboratory method (BRL method). These methods are developed by different techniques, are based on different idealized atmospheres and predict widely different results. The amplification factor applied to account for the effect of focusing must be consistent with the method used to predict the baseline overpressure. Theoretically, the amplitude of the overpressure at distances several miles from the blast site could be more than 25 to 100 times the amplitude of the attenuated wave predicted by the BRL method. However, based on comparisons with measured overpressure data is probably less than approximately 3 times the amplitude of the attenuated wave as predicted by the NOL method. This paper is based on research conducted as part of investigations of airblast damage complaints associated with an accidental explosion near Eveleth, Minnesota and with the disposal of military explosives by detonation at the Sierra Army Depot near Herlong, California. The techniques available for estimating the airblast overpressure that might be generated at various distances from the blast site and criteria for evaluating the potential for damage are examined.

Jan 1, 2004

By John Platt, Mark Stephens

"When blasting is required in critical areas and anticipated shot movement and quick cleanup areessential to the success of the project it is extremely important to use the best technology available to achieve the goals expected by the customer. Wampum Hardware was given such a challenge in 2014-2015 when the PA Turnpike and New Enterprise Stone and Lime hired the company to do presplit blasting along the PA Turnpike. The face height averaged 45 feet (13.72m) and the shots had to be controlled to stop within 60-75 feet (18.29-22.86m) of the face or in this situation before they entered the travel lanes on the PA turnpike. In many if not most blasting environments, it is essential in controlling the movement of a blast, to make certain that the face holes are drilled at exactly the right place, with the proper amount and type of burden in front of and to the sides of the borehole. Profiling is an important first step to insure that the holes are drilled at exactly the right place and showing us the correct amount of burden in front of each and every drill hole."

Jan 1, 2016

By Gunnar Persson

The borehole pressure/time history of blasting practice is simulated in a twin pendulum apparatus, where the expanding shotfiring gases force two steel slab swingers apart. A pilot installation built at SveDeFo is described. The relevant factors, that govern the use of this test method as a means of classifying explosives with respect to their toxic fume potential, are described.

Jan 1, 1996

By Kfw Eick

The paper describes the use of the Nonel millisecond delay blasting system in narrow, deep, tabular ore bodies and briefly describes the standard stoping method as used on Harmony Gold Mine and compares this with the new Nonel short panel system.

Jan 1, 1990

By Robert Hopler

Although electrical instruments were being widely introduced into the study of seismic tremors, attempts to understand and quantify shocks from blasting continued to use rather primitive methods well into the 19th century.

Jan 1, 2007

By Robert L. Brooks

Blasting liability problems are frequently compounded by a company's inability to effectively communicate with concerned property owners and the lack of adequate complaint documentation. Often, by the time the insurance carrier becomes involved in a blasting claim, the situation has deteriorated to the point that a solution agreeable to both parties is virtually impossible to reach. The insurance carrier, wishing to minimize their lose potential may decide to pay on a somewhat questionable blasting claim rather than be drawn into lengthy civil proceedings that would ultimately end up in front of a jury with little chance for a successful outcome.

Jan 1, 1992

By J Brent Gilion, Gary Eck, O Machacek

The research presented herein is the result of internal efforts as well as efforts under subcontract to United Technologies Chemical Systems Division San Jose, California . The efforts were focused on investigating the feasibility of using excess energetic materials from the Department of Defense and Aerospace Industries as ingredients in commercial explosives. The management of the excess energetic materials inventory in this country has become a serious problem facing the Department of Defense and its contractors, the Aerospace Industry and both state and federal regulatory agencies.

Jan 1, 1994

By Jesús V. Saccsa, Kenji B. Loayza, Erick M. Condori, Jorge A. Velásquez

This research investigates how to reduce manufacturing costs of a safety fuse composed of black powder, replacing its ingredient NO3K by NO3Na for processing, and contributing to minimize costs per blasting.

Jan 1, 2017

By Piet Halliday, Ellina Kharatyan

Conventionally, emulsion matrices (unsensitized) need to be sensitized to become detonable explosives. This is done either chemically or mechanically. Both methods have their advantages and disadvantages. Mechanical sensitization involves the addition of microballoons (plastic or glass) to the emulsion matrix, in order to create hot spots during detonation. This is usually done at the manufacturing site and poses a safety risk in terms of the storage, transportation and handling of a 1.1 type explosive. Many countries throughout the world make use of chemical sensitization as opposed to mechanical sensitization as this allows for the storage, handling and transportation of two 5.1 type products rather than the 1.1 type explosive. Chemical sensitization involves the addition of a small amount of a chemical that reacts with a component of the emulsion matrix causing the formation of gas bubbles that act as hot spots during detonation. The disadvantage of this is the lack of accurate density control (due to various factors affecting the reaction) and the lack of comprehensive understanding of the operators of the reaction. This can easily result in poor blast performance. Due to these disadvantages a pumpable, non-detonable (5.1 type) mechanical sensitizer was researched and developed. This product allows for pumping at a 50:50 volume ratio with the emulsion matrix, when loading into blast holes. The significance of this is that a 1.1 type explosive is formed in the blast hole. As such, the security and logistical issues of the transportation and storage of the 1.1 type explosive are eliminated. Another advantage is accurate density control of the final product, specifically in small diameter long hole applications. A cost effective, unique mini pumping system has been developed for the loading of this product. Moreover, this system can easily be used for secondary blasting applications and the on-site packaging of cartridged explosive products.

Jan 1, 2015

By Terra Dinamica, Frank Lucca

This paper discusses blast design for vibration control in tight construction blasting. Topics include blast pattern geometry, blast design formulas, loading, explosives & initiation selection, and utilizing borehole deviation equipment and lasers, and rules of thumb. The paper will also explore vibration prediction, neighbor relations, and related topics, such as blast plan submittal. Various projects from metropolitan construction blasting operations will be used as examples. Examples include blasting in the inner city, next to pipelines, and in housing developments.

Jan 1, 2005

By Tristan Worsey, John Henchion, Nathan Rouse, Yannick Lauras

"This paper presents an approach used to plan and evaluate drill and blast trials for a mine that currently mechanically excavates in-situ rock. The document presents the approach used to plan the trials, the key performance indicators (KPIs) that were necessary to evaluate the mining methods, the test matrix used during the trials, and the results of the trials. The trials, which occurred as part of an overall drill to mill optimization project at this site, helped to evaluate various blast designs using fragmentation results,drilling and blasting costs, and downstream costs. This project was unique in that (1) drill and blast methods were trialed on multiple rock types and various bench heights using a range of blasthole diameters and powder factors and (2) the load and haul costs were evaluated using a range of loading equipment, from 66 tonne (73 ton) excavators up to 250 tonne (276 ton) excavators. A ten year net cost financial evaluation of the material extraction alternatives was also prepared for the site management. Ultimately, the process of evaluating the drill and blast trials helped the management decide whether to continue extracting using mechanical methods or to introduce drill and blast methods to extract the rock."

Jan 1, 2017

By Robert B. Hopler

Emplacing explosives in the borehole by bulk methods is utilized today for about 35% of all of the explosives used in the United States. Although different from today's methods, some bulk emplacement has been utilized throughout the history of explosives. This paper provides an overview of the evolution of the industry from primarily packaged to primarily bulk materials and methods.

Jan 1, 1992

By G. A. Walsh, M. Timm, S. M. Geerts

This paper will discuss the effectiveness and the general use of improvised shaped charges. Testing was conducted by the New Mexico Tech Student Chapter of ISEE and held at EMRTC. The first series of tests conducted was to illustrate the performance of different features of the shaped charge. A PVC pipe filled with C4 with no cavity, PVC with an unlined conical cavity, PVC with a copper lined conical cavity and no standoff, and lastly a PVC pipe with a copper lined cavity and a 1.5 cone diameter standoff.

Jan 1, 2010

By Stephen Mansfield

In metalliferous mining operations, subdrill is that portion of the blast hole that is drilled below the target grade elevation, and in most cases loaded with explosives. Its primary aim is to enable efficient excavation down to the target floor level. Subdrill is often described as being expensive and that excessive subdrill should be avoided, as it can result in damage to the subsequent floor, lead to difficult drilling conditions and higher vibration levels. As a result, many operations aim to apply the bare minimum amount of subdrill in order to excavate to the target floor

Feb 1, 2020

By Mark A. Williams, James D. Humphrey

Without question, draglines are one if not the most effective tools available to the surface mining industry for overburden handling. With few moving parts and a two- or threeman crew, this machine silently sits and chews into millions of yards of overburden annually. A 100 cubic yard machine operating for 30 years will excavate three-quarters of a billion yards of material during that time. That is 750,000,OOO yards of material!

Jan 1, 1990

By Johan Gjødvad, Catherine Aimone-Martin, Charles Dowding, Mathias Jern

A residential structure adjacent to a quarry in Ohio was instrumented to record structure motions, resulting wall strains and existing crack displacements in response to close-in blasting within 82 m (270 ft). The project is a cooperative effort among international experts representing the European Federation of Explosives Engineers (EFEE) and ISEE supported by more than 21 persons from eight different countries to compliment prior work performed at the Aitik Mine in northern Sweden. The focus of this study is to compare blast-induced vibration measurements relative to regulatory compliance limits as a percentage of allowable velocities among eight different countries for a one-story residential wood-frame structure with a brick-and-mortar exterior and full basement. Participating counties included Austria, France, Germany, Norway, Sweden, Switzerland, the United Kingdom (UK) and the United States (US). Geophones were placed on the foundation and in the ground in accordance with each country’s regulations to record peak velocities as a function of frequency or distance to blasting. This study extends the work performed at the Aitik Mine to include interior corner geophones to calculate global wall strains and micro-m (micro-in) displacement gauges mounted over an existing drywall crack to measure blast-induced dynamic crack responses and climatological influences on daily opening and closing of a crack. Structure responses were documented for 68 blasts conducted north of the structure from February through September 2023 of which 17 blasts were selected for detailed analyses. The highest in-ground PPVs recorded were 43 mm/s and 59 mm/s at the NE and SW corners, respectively. Measurements from these blasts plotted within each country’s limits provided a comparison of stringency among the counties. The percentage of compliance limits among counties ranged from an average of 114% for the US, UK, and Austria limits to the highest of 585% for Switzerland. Despite these high percentages of compliance for all countries, the global tensile strains induced by these blasts were at most only 12 μ-strains and occurred with the highest velocity blast that exceeded each county’s limit. This high percentage of compliance and low strain level demonstrates the restrictive nature of the regulations studied. Peak dynamic crack opening and closing during blasting averaged 20 -m (0.0008 in) while the 12-hour weather-induced crack displacement during the time period over which blasting occurred averaged 200 -m (0.008 in) and the largest 12-hr change in crack width was 356 -m. This low level of crack response validates the observation that the studied regulations have highly conservative limits for cracking potential of standard building materials.

Jan 21, 2025

By Ery Wardhana, Stefanus Jagad, Relinda Sanistya, Hasucita Tausi, Rido Situmorang

The blasting process is one of the most high-risk activities in mining operations. Shotfirers and blasting crews face hazards from slope failure, toxic gas and fumes, or unstable ground condition every day of the blast. But on the other hand, to ensure all of the holes are detonated, shotfirers are required to reenter the location to check. With advances in technology, nowadays the use of drone in mining is not something that is rarely seen. It has been used for mapping and slope-monitoring. This paper will discuss the application of drone for blasting process in a mining pit in East Kalimantan, Indonesia. By using drones, it is not only safety factor which can be improved but also operational efficiency and technical analysis. The duration it takes for post blasting process can be reduced because the drone can directly enter the location after blast. The technical analysis for the blast can also become more comprehensive, as the before-after photos and video documentation can be taken with wider view. It helps with fly rock calculation and fragmentation analysis too.

Feb 6, 2023