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By Fumihiko Sumiya, Yukio Kato, Yoshikazu Hirosaki

Secluential blasting is one of the most popular methods in blasting. tiowever, it is well known that an emulsion explosive can be dead-pressed by dynamic pressure generated by the previous detonation. It is difficult to gain the expected blasting performance due to tb.e malfunction of explosive caused by deadpressing and shock desensitization. Such malfunction of an explosive is undesirable for safety blasting operation. Voids in the emulsion explosives will considerably affect the performance of explosives such as sensitivity, detonation velocity (DV), pressure-resistance and so on. To clarify the detonability and the performance of precompressed emulsion explosives, the DV was measured. Three types of microballoon or micro bubble ; two types of glass microballoon(GMB), resin microballoon@MB) and chemical gas bubble ; were used as sensitizers for the sample emulsion expiosives. The underwater explosion test was carried out to load dynamic pressure into the sample explosives. The dynamic pressure was generated by the detonation of a donor explosive, and the DV of the sample explosives as acceptor was measured by ionized gap terminals. The dynamic pressure level and initiation interval for the donor and the acceptor were chosen as experimental factors. The detonability was carefully investigated at short initiation intervals taking into consideration the interaction between same delays caused by the deviation of the ignition time of the electric detonators. From these experiments, the following results were obtained ; A) The DV of precompressed emulsion explosives was low compared with that of uncompressed emulsion explosives in all pressure conditions. B) The decrease of DV in the sample explosives sensitized by GMB s was larger than that of DV in the sample explosives sensitized by RMBs or chemical gas bubbles. C) The recovery of the detonability occurred rapidly in the sample explosives sensitized by RMBs and chemical gas bubbles. However, a long period was needed for the recovery of detonability in the sample explosives sensitized by GME! s. It was concluded that the type of microballoon and micro bubble significantly influenced the detonability of precompressed emulsion explosives.

Jan 1, 2002

By Owen Collins

In surface mining, designing patterns to reduce the probability of flyrock and optimizing fragmentation through powder factor calculations are important for safe, efficient blasts. The designed powder factor is established for the blast once parameters such as burden, spacing, stemming, and powder column height are determined. In practice, these parameters are usually constant throughout a production blast with row-to-row burden and spacing. However, challenges can arise with the introduction of an open face. Many variables could necessitate the adjustment of the face row to optimize blast results. Variables include drill accessibility, challenges with toes, overhangs, and geology. The approach is often, but not exclusively, determining how to keep a consistent powder factor from the open face through the body of the blast. However, the solutions used vary case-by-case and rarely are two blasts the same. Technology has improved the ability to deal with challenging face conditions. 3D modeling with the aid of drones allows the application of angled holes to be more effective and simpler. This is just one instance where technology has improved blast results. This paper will present solutions to challenging face conditions. Thoroughly analyzing instances where challenging open-face variables were met with an effective blast solution could help provide insight as to what yields consistent blast results.

Jan 26, 2026

By Christodoulos Xiouris, Ali Reza, James Karnesky

A rocket parachute signal flare is often used to signal a maritime emergency. In the general operation of these devices, a solid rocket motor propels a metal body to an altitude of approximately 1000 ft(305m).At the end of the rocket motor, a propelling charge drives a signal flare and parachute out of the metal body and ignites the flare, which then burns for approximately 40 seconds as it falls to earth. In this paper, we describe an engineering investigation of an accidental ignition of a rocket parachute signal flare, which caused injury to the user. The components of the flare involved in the accident were inspected via x-ray and microscopic imaging techniques, and compared with those of unfired flares recovered from the same vessel. Chemical analysis of residue on recovered components from the accident flare was also performed. These comparisons were used to determine the likelihood that the actuation mechanism had been deliberately manipulated. In the subject model of the flare, ignition of the rocket motor is accomplished through a percussion cap which is struck by a firing pin. Prior to activation, the firing pin holds down a pre-compressed spring. We present a comparison of the ignition system of the incident flare with those of other rocket parachute flares, which do not incorporate any stored mechanical energy.

By Joshua Hoffman

The recruitment and retention of future talent into the explosives industry is becoming increasingly important. Student chapters help with this effort but what are they doing and are there things they could learn from each other? This paper discusses the University of Kentucky Student Chapter's efforts to grow membership, retain its recruits, and integrate them into the explosives industry. Several social and professional events during which the students are able to meet and network with members of their future industry are introduced. The special relationship that has been fostered between the University of Kentucky and Missouri University of Science and Technology is discussed. Professional development initiatives which are critical for a student to become vested in the industry are shared in this paper. These opportunities which range from internships to research positions allow a person to get a better understanding of the explosives industry and find the niche that best suits them. Many of the student chapters are closely connected with engineering programs. While this makes sense and both entities benefit from these arrangements there is a trend of job placement primarily in the engineering industry. By providing these students with the chance to learn more about the explosives industry and get hands on experience more of these future engineers and professionals can be retained after their graduation.

Jan 1, 2013

By Corry Goumans

The job location is at Bear Lake Hydro Project located north of the town of Sechelt, British Columbia, Canada

Jan 1, 2013

By María Virginia Ramírez, Alejandro Alarcón, Alea Reyes

Reactive grounds (presence of FeS2, CuFeS2) can create hazards in a mine; misfires to premature deflagration or detonation of loaded blast holes. This occurs because some minerals can react to ANFObased explosives. Due to a high potential event that occurred in The Mine in 2013, The Mine and the Explosive Provider (“The Company”) are conducting a soil characterization of the areas containing reactive sulfides. This study was planned along with The Mine and it is being developed by a multidisciplinary team.

Jan 1, 2018

By Valeri Mitkov

Studena Quarry is one of the main suppliers of inert materials for concretes production in Sofia. It is characterized by massif heterogeneity in density and fissuration. Failure to take into consideration this fact during the planning of the blasting works recently had unsatisfying results in their carrying out – obtaining of materials with too small dimensions or high percentage of outsize material. Series of test blasting were carried out to find the relations for calculation of the main parameters of the drilling and blasting works. The blasting network was enlarged to 6 x 6 m, the diameter of the shot-boreholes was changed from 110 to 152 mm, the stem of the boreholes was significantly reduced and the relative consumption of blasting agents as a whole was reduced to 0,37 ?g/m3.

Jan 1, 2010

By Paul Worsey, Braden Lusk

Differences exist between public perception of construction blasting and quarry blasting. In general, people are able to tolerate short term inconveniences much better than long term ones. The paper focuses on the public perception of quarry blasting in St. Charles County, MO. This expanding urban environment has seen new legislation targeting preexisting quarry operations that have been in place for many years. A survey was made comprising interviews conducted to gauge perceptions of persons with varying demographics. Interviews covered topics involved with quarry blasting and its reporting methods. The purpose of the interviews was to determine public perception of blasting and how best to report results of vibration measurements. The use of different, less technically complicated measurement scales for vibration and airblast was considered as an alternative reporting system. The question for the industry is, “Has our past haste in adopting complex scientific scales and units been detrimental to us?” In other words, are we reporting the correct things? For airblast, the decibel scale was evaluated against millibar in the public eye. Peak Particle Velocity was also compared to that for displacement. Current legislation in the county is based on complaint levels rather than damage criteria. The complaints most likely not only come from ignorance to the affects of blasting on structures, but also sparse understanding of the units used to report these affects. The past practice of treading softly as an industry has been proven to be a poor choice, and education of the public as well as lawmakers on all levels is necessary. The Mississippi Valley Chapter of ISEE has begun to conduct seminars to this end. One educational seminar has taken place for officials and lawmakers in the St. Louis area, and others are in the planning stages. The focus of this paper is to gauge perception of the damage criteria reported today, and locate focal points for future education of the public in rapidly expanding suburban environments.

Jan 1, 2005

By R. Narendrula, S. P. Singh

The productivity of a loading machine is affected by several factors. One of the most significant is the characteristic of the muck being loaded. A study was conducted to examine the effects of the looseness, angle of repose, size distribution and moisture content of the blasted material on the efficiency of the loading machine. The study was conducted in the following stages: (a) controlled experiments in the lab, (b) tests with loader simulator and (c) field work in an operating mine. It was found that looseness (%void) in the muck increases with the increase in the value of the mean particle size and index of uniformity of the fragmented rock. Looseness and angle of repose affect the fill factor and the digging cycle time of a loader and in turn the productivity of the equipment. Moisture content affects the angle of repose as well as the stickiness of the material to the loader’s bucket. It was observed that the angle of repose increased with the increase in the mean particle size and the moisture content of the muck. It was also found that the bucket full factor and rate of scooping decrease with the increase in the values of mean particle size and index of uniformity. This was also conformed during fieldwork that bucket fill factor decreases with the increase in the mean particle size as well as the index of uniformity.

Jan 1, 2005

By Robert Hopler

SECTION 9.---BORING AND BLASTING.*155. Blasting is the operation of bringing down and detaching from its bed or position masses of material by means of explosives.

Jan 1, 2011

By Johan Finsteen Gjødvad, Mathias Jern

The paper is part of the ongoing work of the Environmental committee of EFEE. To assist the European experts working with explosives one of the aims is to improve the common knowledge of similarities and differences between national legislation, standards or guidelines on vibration monitoring and other environmental monitoring during blasting in Europe and abroad. This has been done by use of an online survey through the most of 2018. Questions have been raised on vibration monitoring during blasting. The existence of norms, guidelines or standards and how they are used. Even though the questions have been kept at a high level they are formed to try to map the different national standards use of such things as frequency, guidance on monitoring position, distinction between different types of structures, requirement to the equipment and more. Furthermore a few initial questions have been raised on other environmental monitoring relevant for blasting. The respondents are national, cooperate or individual members of EFEE. The answers are experts in the use of explosives and vibration-monitoring in their respective countries. More than 60 have answered the questionnaire from 29 different countries. Mainly European as well as other nations including India, Israel, Nigeria, Saudi Arabia, UAE, USA, Greenland and Hong Kong. By analysing the incoming answers, the differences and similarities in vibration monitoring of the respondents has been clarified and mapped. Where possible other environmental monitoring has also been analysed. Where needed the different guidelines, standards and regulations have been visited to verify the answers and further elaborate on the comparison.

By Neal Lee

Reduced relief horizontally means an increase in energy expended vertically into the rock surrounding the stemming column, and potentially through the stemming column. The vast majority of holes in any surface blasting operation are afforded two horizontal relief faces at the moment of firing, whether by existing relief faces in front of and to one side, or previously blasted hole(s) in front of and to one side of the holes in question. When the energy expended in any hole on the blast pattern has less than two Horizontal Relief Planes or faces (referred to moving forward here as “HRPs”) available to it at the moment of firing, a higher percentage of the available energy is directed vertically. In the analysis of recorded videos by the author, one will note the fact that stemming ejection/flyrock is observed to a much greater degree from the center of almost all patterns when they are timed to “pull out of the middle” (“box cut" timed patterns). This is because the first hole to fire in each row has only one Horizontal Relief Plane, which significantly decreases horizontal avenue for energy release for these holes. This of course results in an increase in the amount of energy expended vertically. This paper proposes a novel methodology to modify the stemming to better use the explosives energy of each hole, while controlling side effects such as flyrock and airblast.

Feb 6, 2023

By M. K. Ameen, R. El-Hacha

This paper presents the analytical results obtained from numerical simulation of reinforced concrete slabs strengthened with various FRP systems and subjected to blast loading. A three-dimensional finite element model using AUTODYN software was used to predict the overall behavior of the slabs. The numerical results were validated by comparing with experimental results from a program carried out to investigate the efficiency of different strengthening systems on the blast resistance improvement of small-scale reinforced concrete (RC) slabs. The experimental program consisted of testing nine RC slabs strengthened with three different externally bonded (EB) FRP systems attached at the bottom side of the slabs and one RC slab tested without strengthening for comparison purposes. The EB FRP strengthening systems investigated included two layers of Carbon Fiber Reinforced Polymer (CFRP) sheets, two layers of Glass Fiber Reinforced Polymer (GFRP) sheets, and one layer of Glass-Fiber Resin Polymer (GRP) sheet. Different epoxy resin, patching mortars and impregnating epoxy adhesives were used for the slab surface preparation and FRP system application of the strengthening layers. The aim was to evaluate the residual strength of the test specimens after exposure to blast loads. The blast loading parameters were evaluated for each test using AUTODYN simulation and compared with the computer program CONWEP. All specimens were subjected to same spherical TNT charge weight and stand-off distance with the respect to the slab top surface. Extensive comparison is made between the experimental results and the AUTODYN simulations for the control unstrengthened slab and the strengthened slabs including time history records of the bottom steel strain and mid-span acceleration and the peak dynamic deflection of the slabs.

Jan 1, 2010

By Thomas Palangio, Blessing Taiwo

Image-based fragmentation analysis is increasingly utilized in blasting operations to evaluate particle size distribution in a non-intrusive and efficient manner. However, the accuracy of optical granulometry systems can vary significantly with particle size. Higher precision is typically achieved for larger fragments, generally those greater than golf ball size when using drone-based orthomosaic analysis. In contrast, the detection and delineation of fine particles become less reliable due to constraints such as pixel resolution, particle overlap, and partial burial within the muck pile. This variability does not undermine the value of image analysis but rather highlights the need for a deeper understanding of its operational thresholds and the integration of complementary methods or calibration approaches to improve its reliability across the entire particle size distribution. Technologies such as WipFrag, originally developed in the 1980s, are designed to conduct in-situ fragmentation analysis within complex blast environments, where fines are often obscured by larger fragments. The challenge becomes more significant in blast rounds exhibiting wide gradation ranges and increased fines, particularly resulting from excessive energy concentration in high-pressure zones near the borehole. Previously, this issue was addressed through methods such as analytical correction, zoom-merge correction, and empirical calibration using Rosin-Rammler and Swebrec distribution models. However, these traditional empirical calibration approaches, particularly those tied to distribution functions like Rosin-Rammler have shown limitations, especially in accurately representing the fine region of the fragmentation curve. In contrast, the recently developed xP-fan model, which incorporates the relationship between powder factor and fragment size, introduces the fragmentation energy fan principle which Kuz-Ram model does not entail. This paper presents a study on the application of the novel xP-fan calibration to enhance the accuracy of optical granulometry systems. The findings demonstrate how xP-fan help calibrate the fine region of the PSD without deflecting the maximum size.

Jan 26, 2026

By Andrew F. McKown

Overbreak and damage to rock walls at the perimeter of rock excavation can lead to safety problems due to rock falls and additional costs due to a] extra mucking, b] extra concrete or shotcrete to backfill overbreak, c] additional rock reinforcement, d] additional water inflow and e] additional maintenance of rock walls. To minimize these undesirable effects, there are several perimeter control techniques available (i.e. line drilling, cushion blasting, pre-splitting, smooth blasting, and fracture control blasting) which control perimeter hole spacing, burden and loading to provide a smooth, stable excavation contour. Conventional perimeter control loading and hole spacing is satisfactory for massive, homogeneous formations, but when blasting in weathered or fractured rock closer spacing and very light loading is required.

Jan 1, 1984

By P. Lozada

The objective currently demanded from controlled blasting techniques is to minimize damage to the remaining rock mass while protecting the integrity of mine walls and ensuring the quality of the fragmented material for easier extraction. Finding this balance represents one of the three main challenges faced by large open-pit mines. They must achieve mine stability by complying with slope designs while also maintaining good results in terms of fragmentation and equipment productivity. The main constraints are related to unfavorable geological conditions, water presence, limited drilling diameters and available explosive products, as well as managing drilling times and blast scheduling, among others. For slope control, in addition to presplitting, blasting designs generally include buffered rows, drilled with smaller diameters, and loaded with fewer kilograms of explosives than production holes. The objective is to reduce the powder factor (kg/t) to minimize the energetic influence on the walls and attenuate damage. However, this often requires using very short charge lengths compared to the bench height (one-third or less) and reducing the pattern geometry, which increases the number of holes per ton and drilling costs. This traditional technique of reducing powder factor in the buffered rows has the main limitation of not being able to distribute the explosive energy throughout the entire column, leading to fragmentation issues mainly in the steaming area. Measurements conducted by Orica in their operations indicate at least a 30% increase in P80 particle size in the buffer zone associated with this condition. To improve energy distribution, techniques such as decking, or vertically decoupled charges can be employed. However, these techniques cannot be applied under wet conditions, and strict control over implementation quality is required to avoid deviations, which increases loading operational times and resource required. In this sense, the use of less energetic and lower-density explosives is a better alternative. On one hand, they allow for complete charge columns in the buffered rows, ensuring homogeneous fragmentation, and on the other hand, they reduce the energetic influence on the slopes, significantly decreasing vibration levels. With less energy per kilogram of explosive (MJ/kg) and less charge per linear meter (kg/m), it becomes possible to handle higher specific charges and longer explosive columns, providing flexibility in drilling and loading design options without compromising slope stability.

Jan 1, 2024

By Karl Christopherson, Vanessa de Viterbo

Trim blasting is an integral part of the mining processes at the Morenci Mine, a Freeport-McMoRan Copper & Gold Inc. property. Trim blasting near high-walls or Finals blasting requires a tighter distribution of energy but a reduction in total energy factor near the wall. Recent Finals blasting in Morenci Mine was allowing the shovel to dig to the final design limit, but causing high-wall instability due to excessive energy or production of energy (blast design and timing). Slope instability events reduced production in two of the three operating pits in Morenci over 2009. In order to avoid high-wall instability from Finals blasting, a new method was required. The new method utilizes air-decks, unconventional row timing, and blast design based on the geology predicted. Many different geologic structures and rock types exist in Morenci, and different strategies were needed for the many predicted geologies. Drill penetration rate and core mapping were the primary tools for determining the blast design. Patterns were designed within a consistent geology; with weaker rock types receiving a lighter load than the stronger rock types. Penetration rate returned by the drill would be the determining factor on the actual rock hardness. Maintaining the pattern geometry on Finals designs should not be an issue as long as the lb/hole is adjusted to reduce powder factor close to the high-wall. One requirement of Finals blasting should be that the powder factor matches the geology as closely as possible. A softer, fractured zone should use approximately one-half to two-thirds the explosive charge of a competent, sound geological zone. This has been incorporated into the final Trim blast design. It is impossible to protect every high-wall from close-in blasting, especially those with crossing prominent joint sets inclined toward wedge failure, but this new design has provided protection on walls where the mine was encountering problems.

Jan 1, 2011

By Gordon M. Matheson, David K. Miller

Sinkhole development in karst terrains is a serious problem and risk to facilities built in these areas. The potential for sinkholes are a function of many things including the chemistry of the underlying rock, the location of water conductive fractures and fissures in the rock, the natural fluctuation of the ground water table, vibrations from various sources and surface regrading activities. When sinkhole open near quarry operations the occurrence of these features is occasionally attributed to vibrations from quarry blasting. The purpose of this paper is to review the evidence regarding the development of sinkholes as a result of quarry blasting. In general, it has been found that sinkholes result from collapse or piping of overburden soils into cavities or caverns developed within underlying carbonate rocks that have been in existence for many thousands of years. The overburden soils in karst areas are typically clayey and as a result are not subject to densification or liquefaction as a result of vibrations. The primary cause of an increased rate of sinkhole development can be attributed to changes in the ground water table or local surface water drainage. These changes may be caused by seasonal fluctuations, ground water level lowering in drought periods, dewatering of excavations or quarries, or local changes in surface drainage resulting from grading activities.

Jan 1, 1998

By James G. Stuart, Tassilo N. Baur

We will discuss the kind of procedure that we use to predict the no-fire (for safety) and all-fire (for reliability) current levels for any given type electric detonator. The basic idea is to expose several detonators to different levels of electric current, so we can estimate the probability of firing as a function of current. We call this a statistical firing test. But what about the uncertainty in measuring the current? Suppose we are not quite sure what stimulus level we apply? This is the question that we will consider here. This relates to both safety and reliability. Surprisingly enough, we will find that some uncertainty in measuring the levels during our statistical firing test improves our long-term safety and reliability

Jan 1, 2019

By Ulf Nyberg, Changping Yi, Daniel Johansson, Håkan Schunnesson

To investigate the non-ideal detonation properties of aluminized emulsion explosive, a series of tests for an emulsion explosive with 5% aluminum powder additive were carried out with mortar confinement. The velocity of detonation (VoD) and the curvature of the detonation front for different charge diameters were obtained from the tests with a high-speed camera. The burning process of the aluminized emulsion explosive has been modelled with the ignition and growth (I&G) flow model in the LS-DYNA code. A routine based on the optimization program LS-OPT code was developed to identify the parameters in the burning rate function with the detonation velocities and the front curvature radii from two tests. A Perl code was implemented in the routine and was used to calculate the VoD, fit the detonation front and obtain the detonation front curvature radii. The calibrated parameters were used to predict the VoDs and the detonation front curvature radii for the rest cases. The results indicate that both the VoDs and the detonation front curvature radii from the numerical modelling are in good agreement with the experimental results. The numerical results also indicate that the variety of the burn fraction and the peak pressure with the change of charge diameters is reasonable with the calibrated parameters.