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By M R. Hettigner, J Nawrocki, C E. Johnson, P G. Cahill

This study evaluates the effects of both short inter-hole and intra-hole delay times on rock fragmentation and throw. Full-scale test blasts were analyzed at a granite quarry in Talbotton, GA. This analysis provides a representative understanding of timing effects on fragmentation in the field, different from previous lab scale studies that negate the effect of geology. Inter-hole delay times between 0 ms and 25 ms were tested on a series of 4 bench blasts and subsequently examined using photographic fragmentation analysis methods.

Jan 1, 2017

By John Manka

Emulsion explosives consist of an aqueous oxidizer phase, a fuel phase, and an emulsifier. The ability to use lower-cost sources for any of these raw materials presents an obvious economic advantage to emulsion manufacturers. This paper focuses on using low cost waste drain oils as the fuel phase in emulsion explosive applications. Laboratory studies showed that emulsions made from waste drain oils and agricultural ammonium nitrate prills were usable for emulsion explosives though their shear stability was weak. Customer field results proved that waste crankcase drain oil could replace half of the virgin diesel fuel in emulsion explosives to make an effective emulsion explosive product with a very low cost.

Jan 1, 2003

By Tom Snyder, John Brulia

Part I is the first of a series of articles by the authors on hazardous materials (HM) transportation safety and compliance for shippers and carriers who offer and transport commercial explosives in commerce on public highways in the U.S.

Jan 1, 2014

By K Taylor

Small scale tests have been conducted in blasting vessels in the laboratory, where the effects of explosive composition, charge diameter, explosive confinement as well as additives to the explosive were examined on NO, NO2, CO and CO2 production. Fumes were analyzed continuously using a flue analyzer, providing analysis every 15 seconds. The results were compared to previous work conducted in the laboratory and to literature findings. It was found that the type of the explosive was the most dominant factor with emulsion explosives producing significantly less amounts of toxic gases. ANFO was shown to always produce nitrogen oxides, even when fuel rich. Tests were also conducted by detonating explosives in broken rock, simulating the release of products of detonation during the formation of a muckpile. Products of detonation were affected by the presence of atmospheric air or rock around the charge. Gaseous products of detonation migrated through the rock piles at different rates, resulting in a change of toxicity values over time. In the small scale experiments, CO appeared to travel faster than CO2 while NOX was not identified. Analysis of the gases that were released during digging, several hours after the blast, resulted in high temporary concentrations of toxic fumes.

Jan 1, 2014

By Ken Schei, Martin Reed, Samuel Bowser, John Wright

From October 18 through October 21, 2001, United States Antarctic Program blasters opened ten access holes for research divers in 11-ft. thick sea ice at Explorers Cove, McMurdo Sound, Antarctica. During this project, a blasting seismograph with a hydrophone accessory was used to monitor the underwater shock waves associated with the blasting technique. Shock wave values averaged 42.3 psi for initial (cratering) shots and 5.9 for subsequent clearing shots, indicating that the ice absorbs most of the shock wave. The results also provide data for refining safety protocols for divers and for the protection of marine biota.

Jan 1, 2003

By H. Wallin, I. G. Wallace, J. Akhavan, E. Nilsson

Over the past three years the UK together with Sweden, Norway, Finland, Italy have been taking part in a EU funded Leonardo da Vinci programme. More recently EFEE have participated in the project known as the EU15/10/200715/10/2007Excert project which is aimed at addressing the perceived loss of explosives expertise in several EU nations. This could have implications for explosives safety and industrial competitiveness. The paper outlines the work that has so far been done in phase 1 and describes the work planned for the second phase of the project. The paper will describe work in the UK to develop competencies for all explosives workers in both the civil and defence sectors. These competencies in the form of National Occupational Standards have now been approved in the UK and are accompanied by a range of 24 new National Vocational Qualifications launched in May 2006. The paper will show how the standards define knowledge and skills and how these form the basis for vocational qualifications as well as higher education awards and professional qualifications. This UK initiative is now being considered in other EU countries and the project has now been extended to also include Germany, France, Portugal, Czech Republic, Lithuania and Estonia. To support the occupational standards and qualifications work is also being carried out to improve learning provision in the explosives area. In addition to formal educational and conventional training courses a series of workplace learning initiatives are being pursued as well as internet learning packages. Examples of these initiatives will be given.

Jan 1, 2008

By Jerry Newton

The bulk explosives industry is relatively young compared to how long explosives have been in use. It's been around for about forty years, about the length of a person's career. This period of explosives history has seen constant change. The type of product, the manufacture and the trucks that haul it have changed a great deal over the years.

Jan 1, 1997

By Stephen Mansfield

In open-pit mining operations, the drill and blast processes have a significant impact on the downstream operational performance of crushing and grinding of ores and recovery of metal. The blast pattern parameters, combined with the material properties, defines the run of mine fragmentation, which in turn drives the subsequent energy requirements for further processing and mill throughput. A common parameter used to describe a single hole or collection of holes is powder factor, the ratio of explosives to the quantity of material blasted. One often-neglected aspect of calculating powder factor is the explosives contained within the length of hole drilled into the top of the bench from the previous bench, known as subdrill. Explosives in the subdrill directly affect the bench below and thus do not contribute significantly to the results of the upper bench, even though they are traditionally included in the powder factor calculation. This paper presents geospatial data modelling methods that link individual holes from an upper bench to the bench below. This enables a new method for the calculation of powder factor, whereby the explosives in the subdrill from the bench above are included in the powder factor calculation of the bench below. This method allows for a clearer understanding of the impact of subdrill on fragmentation, and how variations in blast designs in the upper bench, i.e. hole diameter, burden, spacing, subdrill length, explosive type, primer position, etc., and accuracy of implementation, i.e. actual hole depths and explosive mass per hole, affect the powder factor and blasting results in lower benches.

Feb 6, 2023

By Walter Voglauer, Elisabeth Zechmeister

Five serial photos show the first second of the demolition of a 75 m high, reinforced concrete tower in the 23rd District of Vienna, Austria. The tower demolition with high explosives was necessary because a 175t excavator could not finalize the destruction with mechanical tools. All mechanical works in preparation of the blast, such as the borehole drilling, were done by civil companies under the responsibility of the contracted demolition company PRAJO. The blasting itself was planned and executed by the engineer corps of the Austrian Armed Forces, Sunday, May 26, 2013. Nearly 800 boreholes filled with more than 100 kg of military plastic explosives were initiated with about 1,600 Austin electric delay detonators in exactly 1,000 ms and 30 steps of delay. The 10,000 tons of reinforced concrete tower fell as planned without any damage to the environment. Photo 5. The rest of the detonators initiate the water pools filled with high explosives forming a bizarre white water front to fight the following strong development of dust. The first 1,000 milliseconds are over.

Jan 1, 2015

By Daniel Johansson, Markus Danielsson, Håkan Schunnesson

In sublevel caving, blasted material flows gravitationally into the drawpoint from above in a periodical manner. This type of flow behavior entails muck pile conditions that are variable along the course of extraction. The effect of this variability on the LHD (Load-Haul-Dump) operation in terms of loading efficiency and ability to undermine the blasted ring is not fully understood as of today. This paper presents results from a field test in LKABs Malmberget mine in Sweden, where the influence of fragmentation on the loading operation has been studied in detail. Drawpoint filming was conducted for extraction of two rings equivalent of roughly 10000 metric tons (~9842 long tons) of material each. The analysis includes fragmentation measurements, muck pile classification, and general estimations in terms of loadability. Further, an evaluation of LHD machines from two different manufacturers was conducted to identify and highlight differences. The results show that fragmentation, muck pile compactness, and flow characteristics are all interdependent. Flow disturbances and the subsequent loading of compacted fine material in the back of the ring have been identified as the main reason for occurring problems and prolonged digging times. However, the ability to sufficiently undermine the blasted ring has been identified to primarily depend on digging depth which is only observed to be high during flow disturbances. An absence of flow disturbances seem to promote high loading efficiency but simultaneously limit the maximum digging depth. A mid-range particle size distribution with a low amount of fines has proven beneficial for overall loading efficiency. The various LHDs employed showed significant variations in terms of ability to handle difficult loading situations (e.g. compactness, boulders, etc.).

Jan 1, 2018

By Keith Maki

This paper details a simple substitution of precise electronic timing in the holes for standard pyrotechnic delays. In addition, we wanted to use two electronics in bottom and top to test the colliding shock wave theory. It also discusses the difficult loading conditions on the Iron Range of Northern Minnesota. No preliminary analysis (Signature Hole waveform analysis) was done to determine the most favorable blast timing for fragmentation increase or vibration reduction.

Jan 1, 2007

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 Hector O. Romero, Paulo C. Fernández A, Christian Rees Prado, Claudio C. Gajardo

In open-pit mining, estimating post blasting displacement and spillage accurately is essential to guarantee operational efficiency, ensure alignment with production plans and their associated key performance indicators. The absence of predictive modeling tools on blasting operations results in several critical challenges, including operational reworks due to deviations in material displacement, significant discrepancies between mine and plant (ore grade dilution included), misalignment with the reported production plan, and increased operational costs due to inefficient use of resources. This study, conducted at Los Bronces Mine operated by Angloamerican, Chile, addresses the application of a three-dimensional simulation tool that, through numerical modeling, is capable of predicting post blast rock displacement. The implementation was carried out in a pit phase characterized by blasts near the pit boundaries, with a high risk of material spillage and potential blockage of the only access ramp to the extraction levels. By the integration of key design parameters, such as blast pattern geometry, detonating time, explosive charge distribution and pre and post blast survey, an optimal calibration was achieved and validated in seven blasting events to date, reaching an accuracy greater than 80% in estimating post-blast rock displacement and spillage volumes. Furthermore, this study allowed the evaluation of different pattern alternatives with and without spillage mitigation measures (use of air decks near the free face), obtaining a high correlation and accuracy exceeding 95% in predicting the selected design outcome, supporting optimal design selections. The result highlights the usefulness of the model as a decision-support tool for blasting engineers and short-term planning, by reducing the need for unnecessary operational reworks, improving geological and operational reconciliation, and ensuring the alignment of the extracting plan with production targets. The current average deviation is 15%, with higher deviations observed in blasts with smaller volumes of spill or where the simulated sequence was changed before blasting. The use of this type of three-dimensional numerical modeling represents a significant advancement for blast engineering and the optimization of key performance indicators in open-pit mining operations.

Jan 26, 2026

By B Mohanty, M Alam, F Gauthuer

A series of eleven full-scale production blasts has been earned out in a limestone quarry to study the effect of delay interval and its precision on overall blasting performance. The quarry employed ANFO and cartridged aluminized emulsion in 75 mm diameter boreholes with 2.6 m burden and 2.9 m spacing on a 6.7 m bench. Both V-cut and echelon designs were studied. The types of detonators tested were regular short period electric detonators with expanding delay intervals, a more precise pyrotechnic-based electric detonator (EXADET) with a fixed (25 ms) delay interval, and the ultra-high precision electronic delay detonator (EDD) with constant (but site-selectable) delay interval. The various techniques employed to assess the blast results are described, and the performance of the three types of detonators compared. The use of both EXADET and EDD lead to improved blast results in echelon design. Of the three delay intervals (25 ms, 38 ms, and 50 ms) studied, the best results were obtained with EDD with a 38 ms delay interval, which translates into a delay of 38 ms/m of effective burden. The results also show the need for modification of current V-cut delay designs to derive full benefits from these high precision detonators.

Jan 1, 1991

By Benoît Pinier, Jason Furtney, Gustavo Sampaio Lopes, Jorge Valencia, Johan Hawinkel

This paper describes a numerical modeling study on the effect of airdecking on vibrations, fragmentation, and movement in mining-related rock blasting. Practice has shown that air gaps reduce blast vibrations and damage while maintaining the required fragmentation and movement, yielding similar blast outcomes with less explosive mass per hole. Given that the premise of “replacing explosives with air” for better blast results is counterintuitive, this paper aims to shed light on the physical mechanisms and processes occurring in a blast with airdecks. It is hypothesized that airdecks are effective and beneficial because they load the rock at pressures lower than what is required to crush the rock. In the airdeck, the explosive gasses directly fracture rock and avoid energy loss due to crushing. In essence, the airgap allows similar outcomes in fragmentation and throw with less total explosive product, as the lower pressure gasses in the airdeck are still effective at breaking and moving the rock. This is distinct from only having less explosive and more stemming, as the stemming reduces the pressure more than an airdeck at the same position. This study uses the blastFoam software (for modeling of single and multiphase flows) to accurately calculate the pressure history throughout a blasthole and air gap. The pressure and gas loading are coupled to numerical models of vibration, fragmentation, and blast movement. Using this modeling technique, a suite of blast scenarios for typical configurations in a range of commodities is assessed with and without airdecks. Rock blasting practitioners have a responsibility to protect communities, infrastructure, and heritage — demystifying airdecks through a better understanding of the physics provides another tool in the blasting engineering toolkit to serve this goal.

Jan 21, 2025

By Adrian J. Moore, Alan B. Richards

Responsible blasting requires that rock throw be controlled to ensure that no danger will result to people and property. This paper describes the development and testing of empirical field calibrated formulae that can be used to evaluate rock throw, provide an early warning of when reduced burden will endanger people and property, and prevent flyrock incidents. Inputs to the formulae are charge mass, burden or stemming height, and a site constant that lies within a general range that can be tightened by site calibration. The output is the distance that rock will be thrown, and this ‘design your own flyrock’ quantification can be used to establish both safe clearance distances, and the critical range of burdens and stemming heights where the situation changes rapidly from safe to hazardous. Examples are given of the use of the model to control flyrock in open-pit mining and quarry operations, in situations which are controlled by both burden and stemming height.

Jan 1, 2004

Explosive manufacture, handling and transportation is hazardous and special precautions should be taken while manufacture, handling and transportation. Various regulations and rules defined in explosive act and factories act of India are discussed in this communication. General process control measures during the manufacturing of different types of explosives are also dealt in detail. Various processes hazardous in manufacture of various explosives like slurry explosives, PETN, detonators, styphnic acid, lead azide and lead styphnate and special precautions to be taken during the manufacture of the above explosives are also discussed.

Jan 1, 2007

By Melvin A. Sannes

The Pinson Mine has several different rock formations, running throughout the pits. The main types of material found are Alluvium, Shale and Limestone. In some instances, all three can be found within one blast pattern. Several areas have broken material, which makes it very hard to drill and to shoot. If not timed and loaded correctly a lot of the explosive energy is lost through the broken material.

Jan 1, 1998

By E Novikov, D Johansson, U Nyberg, A Beyglou, N Petropoulos

Fragmentation is an important factor for improving downstream processes in mine operations. Six trials have been conducted at the Aitik copper mine to investigate the effect of ultra-short inter-hole delay times, i.e. smaller than 1 ms/m of burden, on fragmentation. Swelling, MWD data, and crusher efficiency were also evaluated for trials. According to the results, the effect of examined short inter-hole delay times, i.e. 0.14 to 0.86 ms/m of burden, on fragmentation was found to be marginal. Delay time of 0.43 ms/m of burden resulted in slightly finer fragmentation and larger swell; however, the effect of short delays was overshadowed by the effect of small variations in specific charge.

Jan 1, 2014

By B S. Petri, N T. Rouse

Underground limestone mines generally lack air pressure monitoring procedures and instrumentation guidelines. The blasting industry also lacks an applicable source for air overpressure levels that are produced by blasting operations in underground mines. This became apparent during the development of a new underground limestone mine, where overpressure levels from production blasting needed to be estimated. During the development phase of the mine, it was imperative that newly constructed underground structures be capable of withstanding the overpressure produced by blasting. Therefore, a study was conducted to (1) identify and review any published studies for data that may be applicable, (2) identify the appropriate equipment required to record the overpressure levels, (3) determine the proper procedures for setting up the equipment and recording overpressure, and (4) provide an understanding of the nature of the air overpressure in a developing mine.

Jan 1, 2014