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By Winfried Rosenstock

AEBT has been available for a couple of years and is successfully applied in Australia. Up to now it was mainly used in coal surface mining at the Australian East- Coast. Presently, the proved results reach ~ 50 % reduction of Drilling & Blasting costs and a productivity increase of between 10 and 20 %. In 2003 it was for the first time used in surface metal-mining. The mine features for the time being an extremely difficult geological environment and had above to be carried out in the transition level waste/ore. Reductions of wall control, powder factor and vibrations were the main target.

Jan 1, 2004

By J Silva Castro, Braden Lusk

Information management is important in all disciplines. In mining; collection and analysis of information before, during and even after mining is a keystone to performance. During mining, information is useful to optimize the resources and make appropriate decisions. Current technologies allow for collecting information in real time. Records of blasting activity at the mine are common practice in surface coal mining operations. The most common blast information recorded contains the location of the blast, scaled distance, geometry of the blast, weight of explosive used and quantity of blasted rock. Sometimes due to the proximity of protected structures, seismograph evidence of the particle velocity and airblast levels is required. However, in the majority of cases, the seismograph information is not linked to the blast information. Blast related information is recorded separately from the seismograph information and seismograms are little more than an attachment to the blast record. This fact makes simultaneous visualization and analysis of the technical details of the blast with the vibration and airblast information difficult.

Jan 1, 2012

By Cathy Aimone-Martin, Frank Achuff

The New Mexico Department of Transportation (NMDOT) and the Federal Highway Administration (FHWA) have let a contract to Sierra Blanca Constructors for a design / build contract along 38 miles US 70 in Lincoln County, New Mexico. The project will improve safety of travel along the corridor and facilitate the adopted economic development goals of the state. Proposed improvements include widening the existing highway from two lanes to four lanes, providing left turn lane options at selected locations, improving access for businesses and residences, aesthetically enhancing retaining walls, improving storm drainage and replacing the existing pavement with a 30 year mechanistic imperialistic perpetual pavement design. The US 70 Hondo Valley highway project is situated in a narrow valley with steep limestone walls, passes along a Scenic Byway and numerous historic ranching communities with structures that date back three centuries. The scope of work included requirements to monitor and mitigate blasting, noise, and vibrations. The contract was very presumptive with regard to blasting design and procedures. These included visual impact mitigation to treat and stabilize slope cuts, the Migratory Bird Treaty Act protecting roosting and nesting birds from airblast, and the protection of historic and cultural features such as acequias, wells, and structures. Public involvement affecting the rock blasting design has come from citizen task forces and committees concerned with highwall aesthetics and preserving the scenic byway and cultural resources. Constraints placed on the blasting program from agencies and the communities are often at odds. For instance, blasting must produce stable yet natural-looking walls to preserve aesthetics. Restrictions have been placed on pre-splitting and smooth-wall blasting yet safe slope are of the highest priority. This paper presents details of the design/build process undertaken by the contractors to conduct blast rock in an environmentally sensitive region. Blast designs consistent with good construction practices and used to comply with the many federal and state highway stipulations are described.

Jan 1, 2004

By Hans-Peter Rossmanith

Fracture mechanics (Atkinson 1987, Broek 1988, Rossmanith 1978-2002, 1983, 1997, Kanninen & Popelar 1985) and wave propagation (Graf 1975, Rinehart 1975) form the main ingredients in the new electronic detonator based blasting technology. The full potential of using short delay initiation timing in bench and underground blasting can only be exploited if the underlying physical processes are properly understood. From a structural geology point of view, in many open pit mine operations, blasting is performed in incompetent and/or loose rock. Under such conditions the stress waves produced by blasting very quickly dissipate in the rock mass and often their energy cannot effectively be put to work. This contribution shows the effect of open and closed joints – and to some degree also faulting – on the blast wave field and shows the influence of structural geology on the blasting result. A simple engineering method which combines wave propagation and impact mechanics is developed in order to assist the non-scientifically trained blaster in understanding blasting in blocky rock formations. Extensive use will be made of the so-called Lagrange diagram which was introduced in detail in the author’s previous lecture at ISEE 2003 (Rossmanith 2003). This presentation can be considered a continuation of the 2003 presentation.

Jan 1, 2004

By L. M. Lopez, J. A. Sanchidrian

This work investigates the performance of some of the measurement techniques used in vibrations from blasting monitoring. Two tri-axial geophones with cases of different size, shape and mass were tested in a shaker table. The geophone cases were mounted in three different ways on a granite slab fixed to the plate of the shaker: freely placed, sandbagged, and anchored. A known horizontal periodic motion of constant amplitude, and frequency from 16 to 200 Hz, was applied to the slab. Two amplitude levels of 5 and 20 mm/s (0.2 and 0.79 in/s) were applied when the sensors were sandbagged or anchored and only 5 mm/s when no holding force was applied. The transmissibility of vibrations from the rock to the longitudinal geophone as function of the frequency (i.e. ratio of response of the geophone to the slab motion) has been obtained for each measuring condition tested. The transmissibility is considered a composition of the transmissibility of the rock-to-sensor coupling and the transmissibility of the sensor’s mechanics and electronics. The transmissibility of the coupling is obtained normalizing the total transmissibility with the transmissibility of the seismographs, obtained by a suitable test to which a coupling transmissibility of 1 is assigned. Geophone-to-rock coupling is a resonant phenomenon that may alter the amplitude of the measured waveforms by a factor of 1.2 to less than 0.6. The most accurate and precise measurements are obtained with geophones anchored to rock. On the contrary, freely placed or sandbagged sensors are non-predictable planting conditions that lead to high amplification or damping in most of the frequency band analyzed. It is also shown that existing acceleration criteria to select coupling methods do not necessary lead to good quality (accurate and precise) vibration data.

Jan 1, 2014

By Jim Peterson, Ricardo Freire, Mason Biernat

Variable nature of rock and face conditions, varying execution and changing nature of blasting are making ongoing optimization challenging. Intelligent planning and on-going analytics are required to mitigate variability and convert blasting into a predictable outcome by use of technology. Blasting operations generate a huge amount of data which can be used intelligently for optimization. In this paper, details are provided of a system which is used for blasting data collection in the field – Key details around blast parameters, explosives, initiating system details, video, photographs, vibration and fragmentation are collected in a cloud-based platform. Data can also be collected through a mobility device in the field (even without internet connectivity) and synchronized with cloud-based system. Also, data from various sources can be imported in excel formats in the software including from upstream and downstream processes from blasting. App also gives indication about exceeding of vibration, air blast overpressure, fragment size etc. Thus, making it possible to perform QA-QC before charging and deciding initiation timing and sequence at the blasting site. The data can be processed and analyzed to spot trends, help predict events, and formulate strategies at the design and execution stage. Data gathering of blast parameters, explosive used processing and analysis can be used to optimize operational efficiency, improve safety and environmental controls.

Jan 1, 2019

By Advanced Initiation Systems Inc

10 years in R&D Last 5 years available commercially Worldwide Met strict approvals for manufacturing and use

Jan 1, 2004

By Harley Cheema, Brandon Fryman, John Tatom

A new magazine propagation model has been proposed by the IMESAFR Science Panel for eventual implementation into the IMESAFR QRA program. Initial results from this QRA propagation model are now available.

Feb 1, 2020

By Estefania Aramayo, Jhon Silva, Todor Petrov

Blasting is one of the most critical activities in a mining operation. Nowadays, many quarries have to follow a considerable quantity of environmental restrictions that drive the need to improve the conceptualization, design, procedures, and execution of the blast to comply with all regulations. Airblast is one of the variables required to control when blasting. Airblast is an unwanted side effect of blasting. Airblast is defined as an airborne shock wave resulting from the detonation of explosives. Traditional methodologies used for assessing the overpressure produced by the airblast are based on empirical approximations that require the collection of a series of produced airblasts before they can be used as a predicting tool. Once the data is available, regression analysis methodologies are used to find the constants of empirical laws that, in most cases, establish the relationship between the distance and the weight of explosives used in the shot (scaled distances laws). If using the traditional methodologies, the quality, and representativity of the scaled law established for a particular project are determined in terms of the correlation coefficient; in most cases, the models and their use as a predicting tool are questionable (very low correlation values).

Feb 6, 2023

By S D. Cummings

"CRACKS CONCERN CORPORATION" Was the headline on the front page of the Terre Haute Tribune Star, March 1994. Having spent several years following up on blast-induced damage allegations made this article especially interesting. Knowing that there were no operating mines within 30 miles of this newly built, yet to be occupied building, also made the reading more enjoyable. The article went on to read, "Vigo County school officials have asked architects to find out whether some cracks in walls at the new school are due to NORMAL settling or if they indicate serious structural problems." It is obvious that if there were a mine within "Feeling" distance, blasting and the operator would have immediately become suspect as at least one of the potential causes. More alarming is that the investigation may have stopped there.

Jan 1, 1995

By Mauritz Kotze, Jason Furtney, Ewan Sellers, Sandy Etchells, Tom Szendrei

The development of a simple model for gas flow and burden movement has driven the need to improve our understanding of burden breakage mechanisms for single hole blasts and the interaction between multiple holes in solid and jointed rock masses. Conventional analytical understandings of the burden breakout using the elastic-tensile fracture model were studied and found to provide a breakout angle that is independent of burden in contradiction to experimental data. By considering rock fracture in terms of Mohr-Coulomb plasticity using analytical expressions from the field of cavity expansion analysis an improved relationship between breakout angle and burden is derived until the point of critical breakout at which the angle of breakout suddenly changes from between 90 degree and 100 degrees to zero. This suggests that the critical burden occurs at about 0.6 times the radial fracture zone calculated from the analytical solutions.

Jan 1, 2013

By L. Muñoz, L. Steffen, W. Vilas

The emission of particulate material is one of the several parameters related to environmental control in mining operations near communities. Blasting is an event that generates and leaves a large amount of dust in suspension, which can cause discomfort to communities, generating complaints that can compromise the operational continuity of the mine. The proper management of these environmental impacts is a key factor to ensure a good relationship with the neighborhoods, making a responsible mining in harmony with the environment, giving sustainability to the mining business in the medium and long term. The main goal of this work is to present different techniques and technologies applied in a large-scale open pit mine in Brazil, with operations close to a community, to minimize the emissions of particulate material into the atmosphere. For this, different technical solutions were implemented. First, a non-conventional blasting technique was introduced that incorporates special charging and timing configurations, generating a first upper layer that serves as a blanket to contain a second, higher-energy lower layer. An optimal stemming was also defined in order to minimize ejections and maximize cratering, using the scaled depth of burial theory as well as video and fragmentation analysis. In addition, changes were made in the timing between decks (to guarantee a minimum time between layers) and between holes (changing the initiation point opposite to the free face). Finally, additional measures such as humidification of the bench, use of a wind vane to identify wind direction and the construction of a physical barrier between the mine and the community were implemented as additional mitigation measures. By applying the above techniques together, in some specific zones of the mine, it was possible to considerably reduce the ejections generated by blasting versus conventional blasting without the above measures, which was demonstrated in the field with dual blasts trials. Additionally, it was possible to achieve a vibration reduction in the community of ~30%. This work demonstrates how, by applying these technical solutions, it was possible to minimize the dust and vibrations generated by blasting allowing this operation to do sustainable mining

Jan 1, 2024

By David Jones, Jeff Bregar, Damien Bell

We have analyzed overpressure and ground vibration measurements for construction blasting for a large pipeline project. These field-measured levels have been compared to existing prediction curves in the literature and new curves have been proposed for overpressure and ground vibration for pipeline construction blasting activities.

Feb 1, 2020

By Robert B. Hopler

"The story of packaged explosives begins with the use of black powder (also called gunpowder) in mining. Although discovered in the 13th century, it was not until 1627 that the first records of use in mining is recorded. It took until the early 1800's before its use began in underground coal. Althougha free-running, granular material, its recommended (and safest) manner of use was for the miner to pour it into ready-made or onsite formed paper bags prior to insertion into the borehole. This was absolutely necessary in horizontal or upward-slanting holes."

Jan 1, 1991

By Lance McAnnuff

Whatever system is devised to control noise and ground vibration from blasting operations must present an effective compromise between the rights of the individual to be undisturbed by the actions of others, and the necessity for society, the whole of the population individually and collectively, to have the services and the products of commerce, industry and transportation along with the relaxation of recreational and cultural pursuits, all at a price within the means of the same society. One of the first jurisdictions in North America to attempt to quantify acceptable environmental limits for specific blasting operations was Ontario, Canada’s largest and most populous province. A process for development of guidelines applicable only to quarries and strip-mining operations was begun in 1974 and culminated with their inclusion in a “Model By-Law” published by the Ontario Ministry of the Environment in August 1978. This paper examines the process of development of the final guideline document and its application over the last 25 years. While acknowledging that the published guidelines for air blast and ground vibration control have provided a useful and generally workable framework for the purposes of land use planning and complaint or damage claim reduction, a number of flaws, weaknesses and misinterpretations connected with their application are identified. Recommendations for amendment of the controversial items are submitted with a view to making these and potentially similar guidelines in other jurisdictions, more acceptable to both government and industry.

Jan 1, 2004

By Dale Preece, Joergen Pilz, Zavis Zavodni

An overland conveyor was constructed at a surface coal mine to reduce the truck haul distance and make the operation more efficient. An important element in this system is a truck dump facility to transfer coal from truck to conveyor. Mechanically stabilized earth retaining walls were employed to accommodate the coal processing equipment, including the crusher, in this facility. These retaining walls are close enough to the pits being mined that blasting induced vibrations must be considered in analyses of the wall structural stability.

Jan 1, 2010

By Armin Iravani, Changping Yi, Matthias Wimmer, Daniel Johansson, Santiago Gómez, Håkan Schunnesson

Sublevel caving (SLC) is a mass mining method based upon the utilization of gravity flow of blasted ore and caved waste rock. Drilling and blasting are the initial and the major impact on primary fragmentation and later material flow characteristics. The heterogeneity of rock mass has a great impact on materials’ mechanical properties and plays a significant role in rock fragmentation by blasting. In this work, a numerical model for sublevel caving based on 3D Voronoi tessellations was developed to section rock mass into arbitrarily shaped regions for modelling the heterogeneous rock mass. A coupled finite element and discrete element method was employed to investigate both the fragmentation due to blasting and the gravity flow of ore in a heterogeneous orebody. In the coupled model, the caved waste rock was modelled with loose discrete particles while the orebody to be blasted was simulated with bonded particles. The detonation of explosives was described with a particle blast method and a finite element model was used to model the remaining orebody. The results indicated that the fragmentation at the upper part of the ring is coarse while it is fine at the lower part of the ring. The heterogeneity of rock mass induced some boulders after blasting.

Feb 6, 2023

By Ashwani Jain, D K. Soni

Compressive strength of rocks is often required by mining engineers and quarrying authorities for blasting operations. Uniaxial compressive strength of rocks can be predicted with reasonable accuracy with the help of point load strength tests which can be easily conducted at site by the field staff, simultaneously as the cores are recovered from drilling operations. A number of diametral point load tests and uniaxial compressive strength tests have been conducted on the specimens of different rock types under air dried, and saturated condition as well to study the effect of ground water saturation on strength. It has been observed that due to saturation uniaxial compressive strength and point load strength get reduced to a maximum of 32 and 29 per cent respectively. It has also been observed that uniaxial strength is sixteen times the point load strength in air dried as well as saturated condition. However, this factor used for calculating uniaxial compressive strength may be reduced to a lower value for the safety of miners in field blasting operations.

Jan 1, 1994

By Robert Hopler

CHAPTER I. DEFINITIONS AND CLASSIFICATIONS. Definition of Explosives. SECTION 1. The term “Explosive” or “Explosives” whenever used in this ordinance, shall be held to mean and include any chemical compound or mechanical mixture that contains any oxidizing and combustible units, or other ingredients, in such proportions, quantities or packing that an ignition by fire, by friction, by concussion, by percussion or by detonator of any part of the compound or mixture may cause such a sudden generation of highly heated gases that the resultant gaseous pressures are capable of producing destructive effects on contiguous objects or of destroying life or limb, and includes all the articles specifically mentioned in Section 3 herein, and all other similar articles

Jan 1, 2013

By Natalie Zeleznik, Brian Hawkins, David Bradley, Rachel Gooding, Patrick Wilson

"An Event Tree Analysis (ETA) is an established approach for logically deconstructing and assessing scenarios for probabilistic risk assessment. This deconstruction into a series of understandable eventsfacilitates probability estimation for explicitly defined explosive terrorism scenarios with consideration of modes of possible failure during execution (a scenario is defined through selection of a target, selection of an explosive material, and interdiction prior to arriving at general target location, etc.). Further, each event is decomposed into a range of possible outcomes. The physical action or reality ofthe outcome is statistically represented by “branches” of the event tree (e.g., the terrorist may choose totarget a stadium, hotel, or subway; terrorists may be successful or unsuccessful in acquiring the material)."

Jan 1, 2017