Search Documents

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

By Lizbeth A. Escobar, Phol M. Llanos, Maritza Y. Avila

The present research develops the estimation of critical parameters such as the distances and times between holes to avoid failure due to dynamic pressure in electronic detonators based on the near-field ground vibration model of Holmberg & Persson and the hydrodynamic model of Neyman.

Feb 1, 2020

By Tyler Rockley, Cara Rosen

Blasting at a granite quarry in eastern Maryland produces elevated air blast readings that can fall into the cautionary zone for the state of Maryland environmental regulations on a semi-regular basis. When designing blast patterns in this quarry, challenging geology creates rough and uneven blast faces that can be difficult to capture with 2D laser profiling fully. Utilizing several methods known to manage high air blast results like pattern adjustments, decking, and timing changes have not achieved consistent outcomes.

Feb 1, 2020

By Tyler Rockley, Cara Rosen

Blasting at a granite quarry in eastern Maryland produces elevated air blast readings that can fall into the cautionary zone for the state of Maryland environmental regulations on a semi-regular basis. When designing blast patterns in this quarry, challenging geology creates rough and uneven blast faces that can be difficult to capture with 2D laser profiling fully. Utilizing several methods known to manage high air blast results like pattern adjustments, decking, and timing changes have not achieved consistent outcomes. Accurately capturing and modeling this geology is the key to controlling high air blast. 3D modeling and profiling by drone is the solution to understanding accurate face profiles and real minimum burdens. Using 18 months of blasting data and air blast results to establish a baseline, the comparisons between blasts designed with 2D profiling and blasts designed with drone 3D profiling show improvement in air blast levels. Additionally, shots with completed drilling were drone profiled to understand precise amounts of burden for each borehole. This 'audit' of a blast allows for custom loading of explosives, accommodating the amount of burden present on the blast face. 3Dprofiling is not a new tool in the blasting industry, but a drone alleviates some of the restrictions ground systems face. Controlling and managing air blast, as it pertains to face burdens, requires an understanding of those burdens from all angles. A drone provides that distinct level of insight. The results of this study indicate that drone profiling is managing the customer's air blast readings, allowing the customer to maintain their license to operate within the community.

By Norman Paley

A blasting project was undertaken at the Teck Alaska Red Dog Mine in 2005 to 2007 to determine the extent that using electronic detonators could increase Semi-Autogenous Grinding (SAG) mill throughput. The results of that project were reported at the 2010 ISEE Annual Conference. This paper is a postscript to that project and provides the fragmentation resulting from the implementation of a 15% pattern expansion using electronic detonators.

Jan 1, 2012

By Frederick B. Kuhnow

Harmonic energetic delamination of T2 building is being considered for demolition at a formerly known atomic lab. The T2 building is within a containment structure that is under a negative pressure of -49 Pa (-0.2 inches of WC) so that no remaining radioactive material is leaked out. The T2 containment enclosure is a portal frame-type system that spans east/west over 35.05 m (114’-11 7/8”) and spaced 2.9 m (9’-6”) apart. The west side of the portal frames is supported by a 64 cm (2’-1”)thick concrete wall which is backfilled to the west and open to the T2 basement to the east. The east side of the portal frames is supported by a 61 cm (2’-0”) thick concrete wall that is backfilled to the east and open to the tank farm vaults to the west. A concrete slab-type footing supports both the east and west walls. Transverse walls provide lateral support for the walls as part of the original design. The west wall has an elevated slab that provides further stiffening of the concrete wall between the transverse walls.

Jan 1, 2017

By N. Skopak, W. Birch, A. Douglas, C. Johnson

Determining the origins of air overpressure has been a long-debated topic within the explosives engineering community. Historically, it has been accepted that the initial face movement gave rise to air displacement, resulting in an air overpressure pulse. Later research proposed that the air overpressure pulse resulted from the shockwave rapidly propagating through and impacting the quarry face. Most recently, researchers have derived that air overpressure is associated with the gas phase from which a gaseous product from explosives rapidly pours out the quarry face under high pressure. Significant research has strongly indicated that the time at which the air overpressure pulse exits the face fails to coincide with either the arrival of the shockwave at the free face or the initial face movement. Research has consistently shown that the shockwave arrival at the face occurs before the air overpressure pulse leaves the face. Therefore, to best determine which blast mechanism contributed to the initial air overpressure pulse, testing was aimed at verifying the precise time at which the air overpressure exited the faces compared to when the face first moved. This research describes tests using scaled concrete blocks, which provided the ability to control the key parameters necessary for the research to be successfully concluded. Black powder was selected as the energetic material to eliminate the production of the detonation wave while still inducing other gas-producing effects. The components evaluated were air blast arrival times in front of the face, the initial movement of the blast face, the precise initiation time of the blast hole, timing of pressurization within the rock mass (between borehole and face, or adjacent borehole), and the speed of sound in the air. A detailed timeline was created which portrays the actions within the blast to promote an understanding of the sequencing of events. The results showed that the initial face movement occurred at 17.57 milliseconds (ms) while the calculated time at which the air overpressure exited the face occurred at 7.07 ms. The large disparity continues to reaffirm the premise that the origin fails to coincide with the air pressure pulse. Average pressurization through the block occurred at a rate of 341.23 feet per second (104.15 meters per second) which resulted in the gas release pulse being calculated to exit the face between 4.41 and 6.21 ms. This pulse correlates more accurately with the air overpressure origin timing which will be the focus of continued research. Knowing the precise origin of blast-induced air overpressure will assist in being able to better control it through appropriate blast design.

Jan 1, 2024

By Tyler Rockley, J. P. Remi Proulx, Ruilin Yang

A highwall blast vibration project was carried out to quantify the level of blast vibrations produced from a trim blast in soft rock and a combined production and trim blast in hard rock. Combining production and trim blasts could be performed without exceeding the mine’s vibration limits.

Feb 1, 2020

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 Behrouz Ohadi, Kamran Esmaeili, Bibhu Mohanty

In most metalliferrous open pit mines with heterogeneous orebodies, blast-induced rock movement is a crucial outcome that has unfavorable impact on ore and waste segregation in the post-blast muck pile, resulting in either ore loss (the ore is misclassified as waste and sent to the waste rock dump) and/or ore dilution (waste is misclassified as ore and sent to the processing plant). While many studies have been carried out to assess the influence of blast design parameters on blast-induced rock movement, the influence of rock mass characteristics in these studies have been overlooked.

Jan 1, 2018

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 S. Hosein, W. Birch, C. Johnson

The widespread adoption of electronic detonators has given rise to the development of linear superposition to control the environmental impact on both third-party properties and residents resulting from blast induced vibrations. Linear superposition has become a very effective tool in the hands of blasting engineers and has enabled aggregate reserves to be accessed that once had to be abandoned. This in turn has resulted in more and more complex blasting pattern to be developed that contain multiple rows and multiple decks all with different maximum instantaneous charge weights of explosives. This is then made more complex by having to consider multiple sensitive locations often with different Peak Particle Velocity vibration limits. This paper is a case study of what did happen when a blast was designed that “pushed the boundaries” of environmental blast vibration design and control, without taking fully into account the fundamental geophysical properties of seismic waves. The resulting blast design caused a greatly enhanced s-wave to be created in a critical direction from the blast pattern. The root cause being the s-waves from earlier detonating decks in the blast pattern arriving within 2 milliseconds of decks detonating later in the blast pattern. 209 individual decks were fired in the blast pattern of which 41 pairs of decks arrived at the observation location less than 2 milliseconds apart when taking into account the s-wave speed and direction. The lesson to be learned when using electronic detonators to limit ground vibrations from complex blasting patterns, is that it is just not good enough to look at the planned firing times, a professional blasting engineer must also understand the likely interaction of the various seismic wave types created and their combined impact on any given monitoring location.

Jan 1, 2024

By W. Sharkey Bowers

This study was undertaken in order to determine a conservative estimate of the attenuation rate of vibrations through the shallow limestone in South Florida due to quarry blasting.

Feb 1, 2020

By T Duff

This paper describes results from small scale tests conducted to determine the distribution of pressure on target plates when subjected to loading due to the detonation of a buried mine in various media. The tests are conducted by using saturated sand, dry sand, and water as the loading media. Different stand-off distances are investigated. Kolsky bars and pressure sensors are used to determine the free-field pressure - time profile of the output of the charge at any location on the vehicle bottom. For verification of the pressure results at certain distances, the specific impulse measured by utilizing different size round plates are employed. In order to investigate the loading mechanisms, high speed cameras are applied. The small-scale test results can be scaled to full scale by using verified scaling laws.

Jan 1, 2014

By G. Geremia, M. I. Serrano, L. Costa, Strohaecker

The advances in electronics and the development of more efficient algorithms, allow for the designing of more complex and sophisticated automated systems. The new devices include lighter, faster, reliable, and stronger robot manipulators. One available technology, with relatively low cost, is a simple robot manipulator controlled by remote control. The device has been designed to be used in both mining and law enforcement, where it can be useful for inspection, rescue, gas analysis, and even to manipulate dangerous objects, such as explosives. The applications may even include the rescue of trapped miners in risky environments. The major advantage is the fact that the robot can be controlled with a remote and monitored through a video camera, minimizing human exposure to hazardous areas, where robots can perform tasks in an aggressive atmosphere and confined spaces. This article presents a mining robot manipulator controlled by remote control, using video cameras for positioning and sensors for movements, which are located on the operator's arm. With this system, it is possible to create a sensation of virtual reality, allowing easy operation for anyone trained in dealing with explosives, rescues, or other dangerous tasks. Blasting and mining are becoming perfect applications for robots, and its use should increase very soon. The results are discussed and presented for the brand new Xiru 01 robot manipulator.

Jan 1, 2010

By Robert Hopler

Blasting powder is a slow-acting, black, granular explosive made of sulphur, charcoal and either potassium nitrate (saltpetre) or sodium nitrate. The blasting powder containing potassium nitrate is known as “A” blasting powder; that containing sodium nitrate, as “B” blasting powder. “A” blasting powder is a little denser, a little stronger and a little less hygroscopic than “B” blasting powder.

Jan 1, 2014

By Michael Laing

Blasting regulation and restrictions are tougher today than ever before. When blasting in population centers, strict limitations are often placed on the environmental effects caused by blasting, more specifically vibration and overpressure. Blast-induced vibration can be a tricky thing to manage at times, but there are a variety of options at our disposal to help optimize and manage vibration. This paper focuses on the application of rudimentary signature hole analysis to optimize blasting vibration in localized areas surrounding a mine.

Jan 1, 2017

By Robert Boehnke, Bernd Mueller

This contribution presents an innovative, statistically supported method to predict blast vibrations in rock mass. For modelling the processes during and after detonation, a theory is employed which is based on linear momentum (so-called momentum theory), strongly supported by new measurement methods. During the course of the investigations, the following parameters have been found to dominantly influence vibrations: ! charge WB, includes geometrical factors such as borehole length and diameter (kg) ! detonation velocity cd of the explosives used (m/s) ! distance r between the points of emission and immission (m) and the statistically determined negative exponent n ! factor RM or RS of the rock mass which is related to the specific blast momentum and the drilling and blasting technique used and is statistically determined together with the exponent m (mm/kg or mms/kgm)

Jan 1, 2004

By Steven Richardson, E A. Cameron, Reza "Ray" Jambakhsh

This paper outlines the design and implementation of a method to use Long hole Carbide drilling to blast an "Upper Blind Slot Raise" in the range of 12m (40 ft).

Jan 1, 1992

By Huang Daguang, Paulo Couceiro, Juan Navarro

Mining is typically conducted through a set of interdependent unit-operations, which commonly include drilling, blasting, digging and hauling, in order to deliver the required ore material into the comminution circuit and to remove waste rock with minimum impact in the operation. In such complex environment, the identification of critical paths, and respective interfaces between different unit-operations, are necessary to determine a sustainable long-term operational program. Facing this challenge, adaptive cost optimization strategies are required to increase productivity and revenue while minimizing potential environmental impacts. Since the overall mining efficiency can be strongly impacted by blasting outcomes, an operating method based on the searching of the ideal blast design is required in order to minimize the mine total cost of ownership. The implementation of a consistent continuous improvement program requires specific care in terms of design, control and execution of the different stages of blasting. For that, the application of the most advanced technologies for rock characterization, based on drill monitoring systems, and smart explosive products, allows the improvement and control of blast results by adapting the explosive energy distribution to the rock condition, so as to optimize the performance of downstream stages such as digging, hauling and comminution. This paper describes the application of a heuristic optimization approach, where blast parameters are used as decision variables to evaluate the potential impact of several blasting scenarios on subsequent unit operations, under the continuous ability of modelling, measuring and calibrating operational performances along of the mine cycle.

Feb 6, 2023