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By John Brennan

The Avalauncher has been an integral tool for avalanche mitigation work for close to 50 years. With their ability to place a kilogram of high explosives up to two thousand meters away, they routinely serve as a short range alternative to military artillery. The Avalauncher’s roots can be traced to a pneumatic baseball pitching machine used by Major League Baseball teams in the United States in the late 1950s. Throughout the decades, many modifications have been made to both the launcher and its projectiles. Current technology has allowed the Avalauncher to attain greater accuracies and operational range. In this paper I plan to cover not only the history of the Avalauncher but also explore its potential future.

Jan 1, 2009

By Hung Tran, Qian Liu, Patrick Andrieux, Dave Counter

Blast damage in open stope mining has been an important concern in controlling ore dilution. Severe damage to the surrounding rock mass can result in the caving of waste rock and/or backfill materials, as well as general instability of the ground. The blast damage study conducted at Kidd Mining Division in 1995 was aimed at measuring the damage zone around blastholes and at identifying other factors which influence the damage. An approach and methodology developed mainly by Blastronics, together with Noranda under a project with the Mining Research Directorate, was adopted for this project. The principle was to combine vibration measurement results with borehole camera observations to derive the blast damage criteria at the specific site. The Holmberg-Persson Equation was used for the regression of near-field vibration data. The damage criteria was examined with both borehole camera observation results and rock elastic and mechanical properties. Details of this methodology, including instrumentation, are reviewed in this paper and an implementation case study of the blast damage evaluation is presented.

Jan 1, 1998

By William A. Travnik

For more than 60 years, ESSO RESOURCES CANADA LIMITED has been producing and refining oil at a small refinery in Norman Wells, Northwest Territories, and supplying diesel fuel and other oil products to northern markets. In 1982,ESSOwas granted governmental approval to expend production from the oil field from 475 cubic metres a day to 4400 cubic metres a day. This $800,000,000projectproceeded ahead of schedule for a start up in 1985.

Jan 1, 1986

By Stephan Iversan, Janae Singer

High resolution seismic refraction tomography has proved to be a useful tool to effectively estimate depth of blast induced damage in rock. Excavation blast damage can be as shallow as 1 to 2m (3 to 7ft) and requires resolution at a fraction of a meter for effective imaging. We used an accelerometer with flat frequency response to 1000Hz to record data at spacings of approximately 0.25 to 0.5m (0.8 to 1.6ft) along mine walls. The resulting tomograms of P-wave velocity show low velocity zones which we interpret as residual fracturing from blasting. Experiments on a concrete test block and at two underground mine locations give results that are consistent with fractured rock transitioning to competent rock.

Jan 1, 2009

By Paul Worsey, Ron Ecklecamp, Scott G. Giltner, Ronnie Inman, Terry Drechsler

A blast monitoring program conducted at Chemical Lime Companys new lime calcining facility near Ste. Genevieve, Missouri is discussed. The purpose was to develop blasting criteria for the construction and operation of the lime plant within the quarry operated by Tower Rock Stone. Further, it was imperative to accommodate production requirements into the blasting criteria. The major concern was the effect of blasting on the curing of green concrete during the construction of the storage silos and kiln stacks. In addition to discussing the susceptibility of curing concrete to blast vibrations, the paper also details how this varies with time.

Jan 1, 1996

By Richard H. Granhom

Detonation pressure, or Chapman-Jouguet pressure, is an intrinsic property of an explosive, and like detonation velocity, is an indicator of explosive performance. Pressure and velocity are also important for calibrating computer codes and for other calculations such as the stress imparted to rock or metal by an explosive. The detonation pressures, P~cj, of many "ideal" explosives have been measured indirectly by recording some hydrodynamic flow variable other than pressure, with P~cj being inferred from hydrodynamics and the assumed Chapman-Jouguet equations. One such method is the difficult and expensive "aquarium technique''.] Commercial explosive manufacturers generally rely on estimates of P~cj generated by computer codes not explicitly designed for non-ideal explosives typically used in commercial applications. Over the last decade, U.S. national and government laboratories have developed in-situ gauge techniques such as the manganin gauge, for direct measurement of detonation pressure. Manganin is an alloy of copper, manganese and nickel, and is ideally suited for use as a pressure transducer because its electrical resistance changes with pressure, but is nearly constant with changes in temperature. A simplified manganin gauge technique adapted for use at a commercial test site is described and some initial results from measurements on commercial emulsion explosives are presented.

Jan 1, 1991

By Virgil J. Stachura, Calvin L. Cumerlato

The Bureau of Mines conducted a series of tests to develop a blasting method that would reduce overbreak and rockfall hazards at a limestone quarry in northeastern Wisconsin. Reductions in overbreak were achieved by shortening the main explosive column and reducing the explosive load in shortened stemming zones in shotholes which were to form the highwalls. Two blasthole diameters, 3 and 4 inches, were used with 7 by 7 foot and 9 by 12 foot burdens and spacings respectively. ANFO, Comsol 300, or PowerAN were used in the body of the shots and Gelmax or 40 pct extra dynamite cartridges were used in the reduced load zones. Smoother highwalls were visually apparent, however further analysis by seismic refraction techniques were performed as an aid to studying overbreak within the rock mass.

Jan 1, 1989

By Dieter Froelich, Giles Turcotte

In the near future, Bong Mining Company (BMC) will start mining a new deposit known as Zaweah II which is a narrow iron orebody requiring multiple row blasts with the bench floor as a free face. This called for the development of a new blasting technique. The article delineates the problem and its restrictions related to blasting. It also describes the approach which was taken for developing this new blasting technique which is essentially an application of the cratering theory with near spherical charges. Basic crater tests were conducted using various combinations of hole sizes, explosive strengths and delay patterns. From the results obtained, several alternatives were considered for production blasts and the most promising ones were evaluated.

Jan 1, 1980

By B Mohanty

Full-face blasting rounds have been used to excavate a 4.6-mdiameter shaft at Atomic Energy of Canada Limited's Underground Research Laboratory near Pinawa, Manitoba. Both standard pyrotechnic delay detonators and the newly developed electronic delay detonators (EDD) were used on the project. The full-face blasting technique, employing 89-mm-diameter relief holes and 38-mm diameter blast holes, NG-based explosives, and the regular long period delay detonators, has been standard practice at the site, giving excellent wall control and fragmentation results. The comparison blasts using pyrotechnic detonators and EDDs were carried out to test the operational logistics, timing accuracy and blast results obtained with the latter. The long period pyrotechnic delays ranged from O to 18, with the nominal delay varying between 350 ms and 800 ms. The EDD blasts used the same number of periods, with the respective delay interval between successive periods set precisely at 190 ms and 210 ms for the two blasts. Based on a broad range of critically assessed parameters, the EDD blast results proved to be signficantly superior to those obtained with regular pyrotechnic detonators. The results have been analyzed in detail and the relative merits of the two delay systems have been determined. Alternative designs to derive maximum benefits from EDDs in shaft and tunnel blasts have also been suggested.

Jan 1, 1990

By Robert C. Brown

During a research period lasting over three years, a vast number of seismograms were collected and analyzed. From this data, other than obtaining a host of new information pertaining to the effects of surface mine blast on underground mines, it was found that by mounting seismograph velocity transducers at the center of crosscuts in underground mines, seismograms can be obtained which give fairly accurate information about the maximum levels of vibration, and the associated Of stresses and strains, misfiring of blast holes, delay accuracy and delay overlap. The technique of analysis is a simple one; it involves matching of the frequency of wave or wave groups with the shot card information such as rows of holes, number of holes and the cumulative milliseconds of delays used in the blast holes. Any discrepancy that might exist between the frequency of waves and the expected cumulative millisecond delay for a given row or hole eventually will show up as a mismatch in the analysis. This simple technique enables the seismographer to be involved not only in the monitoring of blast peak vibration, but also in making recommendations as to the choice of millisecond delays, reducing the possibility of delay overlaps and reducing the hazards of blast hole cutoffs.

Jan 1, 1980

By Z X. Zhang

In sublevel caving mines, eyebrow break usually gives rise to lower ore recovery and worse safety in the field. Eyebrow break is caused mainly by two tensile stress waves: one from the front surface of a blasting ring, and the other from the roof of the drift. In order to reduce the two waves and finally to reduce eyebrow break at Malmberget mine, we employed two methods: (1) cartridge charge, and (2) double-primers in each blasthole. The two methods were tested in one ore body called ViRi. A total of 10 rings with the cartridge charge and 25 rings with the double-primers were blasted. At the same time a total of 34 ordinary rings were blasted in the same ore body. The result shows that the eyebrow break is 3.0 m for the ordinary rings, 2.3 m for the cartridge charge rings, and 2.1 m for the double-primer rings, respectively. In addition, the ore recovery for the double-primer rings is increased by 3% on the level of ViRi930, compared with that for the ordinary rings.

Jan 1, 2011

By Miie Shields, Ed Billington

Trail blasters for the National Park Service (NPS) live and work in remote mountain terrain throughout the western states, where any support or resupply may be sporadic and ditlicult and mountain weather affects every activity. Mechanical “aids” are the pick, shovel, rock-bar, wheelbarrow, and a Pionjar or Cobra dritl. The blaster is usually faced with an extraordinary range of work, t?om delay blasts in weathered rock using driiole depths of 18” (46cm) to as little as 4” (1 Ocm), through reducing boulders and talus fields to useable tread, blasting stumps, snags and log-jams, to the explosive disintegration and casting of animal czcasses. One day he/she might provide a 500cf (14 cu meter) anchor excavation for a suspension bridge, the next day directionally fall 60” (1.5m) diameter snags in a camp area, and the following day blast a 3-foot-wide (1 meter) tread bench across a steep bedrock slope. To be effective, the blaster must design each and every blast around desired end result, crew and public safety, maximizing effective use of limited quantities of explosive, and the minimnation of environmental effects. Since almost all drillhole blasting occurs in the weathered zone of the rock, blasting is more the art than the science of judging rock density, hardness, cohesion and prefracturing, and selecting explosives, drill and delay patterns, and loading techniques responsive to those conditions. For these reasons the NPS issues its own Blaster’s License, with a basic requirement of at least 40 hours of NPS blaster training and 3 years of supervised Blaster in-Training experience. The focus of this pre-license requirement is on safety and using explosives as a precision tool, versus just “blowing things up”.

Jan 1, 2002

By Paul Worsey, Richard P. Ayres, Mark F. C. Schmidt

A new alternative technique designed to reduce rock scatter and flyrock during boulder blasting is being developed at UMR. The method uses small explosive charges and is designed for shooting in close proximity, while utilizing common blasting products found on the operators’ site. This ongoing work is being conducted internally as graduate and undergraduate level research. A paper describing the general technique was published in last year’s proceedings. This particular portion of the work was performed as an undergraduate research project as part of the requirements for the explosives emphasis degree option at UMR. Previous model work was performed using cubes of concrete. However, in real life boulders are often flat and irregular rather than perfect cubes. The purpose of this work was to determine how to deal with flatter boulders. The work comprised using different geometry blocks (simulated boulders) of the same volume (1 cubic ft.). Square concrete boulders using an 8.5bag concrete mix were cast using different width to height ratios (varying from 1: 1 to 3.7:1). Single 5/8 inch holes were drilled to 2/3 the depth of the blocks, charges placed approximately l/2 way in to the holes and the holes filled with water. The explosive charges comprised ICI Masterdets containing a OSg High Explosive base charge and incremental added weights of C4 explosive. In the experiments, the block height was progressively reduced and to compensate the charge weight was increased until acceptable fragmentation was achieved. It was found that a significant increase in charge wt is required to achieve the same fragmentation as the width to height ratio increases (the boulder becomes flatter). Furthermore, the increase in charge weight required is proportional to the width to height ratio. Basically, you have to use a higher powder factor for flatter boulders.

Jan 1, 2000

By Paulo Couceiro, Manuel Lopez Cano, Carlos Rodgriguez Calvo

Apart from its difficult execution, underwater blasting is one of the most critical operations of the blasting techniques; mainly because of the ground vibrations - normally associated with low frequencies -, destructive hydraulic shock waves, the difficult coordination, and high costs. To solve these challenges during the underwater blasting on the expansion program for the Panama Canal “Widening and Deepening of the Pacific Entrance and the South approach Channel to the Third set of Locks of the Panama Canal”, a new method to blast using bulk explosive, developed by MAXAM, was used. The project was successfully executed, and more than 800.000m3 were blasted in less than 5 months, jointly with the biggest underwater drilling platform ever build, the Yuan Dong 007, with ten hydraulic drills on board guaranteeing a high production, excellent fragmentation result, total control of the vibration levels, no complain of the neighborhood surrounding the area of the project and simple local logistic due to the classification of the main product used (an oxidizer classified as 5.1). That was finally sensitized down in the hole.

Jan 1, 2011

By Pierre Auger, Benoit Levesque, Richard Martel, Guy Sanfacon, Louis-Charles Boutin, Marc-Andre Lavigne, Patrick Brousseau, Luc Trepanier, Louise Galarneau

Explosives used for blasting operations in civil engineering works, like construction of piping systems under roads, of pools, of houses and buildings can generate large volumes of carbon monoxide (CO). Carbon monoxide can represent between 1 to 3% of the gases produced by usual explosives. The production of 10 to 24 1 of CO by kg of explosives blasted is theoretically anticipated. CO is a gas that has no characteristic colour, smell or taste. It can migrate in the fractured rock of the blasted areas on fair distances, and then infiltrate in closed spaces like sewage systems, manholes, but also in basements of houses. In Quebec, in the last 10 years, 7 people were poisoned by CO in their houses to the point that they had to be treated in hyperbaric chambers. In the USA, many accidents have occurred and one worker died in a manhole. From the review of intoxication cases, the distance of migration of CO may reach 55 m if a conduit is present underground. Underground conduits broken by blast, tilling around underground conduits in road or house trenches, or fractured rock created by blasts between houses or between a house and a road, are the different pathways identified in the Quebec incidents. Field tests were performed at sites close to CO intoxication locations in order to evaluate the behaviour of CO in fractured rock following blasting operations. From these tests, the following conclusions may be drawn. The structural geology of the rock formation (schistosity, family of joints, fractures) plays a role in the direction and extent of gas migration in fractures generated when rock is blasted with explosives. The confinement of the rock can affect the quantity of gas migrating in the fractured rock. Significant concentrations of CO may persist in the fractured rock even 7 days after a blast. Advection is the initial mechanism of CO migration in fractured rock generated by the blasts or naturally occurring before the blast. The distance of migration with this mechanism is short (5 to 8 m). In trenches of muck (equivalent to tills under roads) the distance of CO migration by advection is 12 to 20 m. In the 2 to 3 days following the blasts, further CO migration up to 15 m is made by diffusion in the induced fractures, or up to 30 m in the trenches. To minimise CO production and migration in the fractured rock during blasting, special procedures can be applied by the blasting contractors: (1) do the complete excavation of the overburden before drilling and put mats for each blast; (2) do the complete excavation of the muck after each blast; (3) the last blasting should be the one for the private services entrance of the house and the excavation of the muck should begin at the junction between the road trench and the services entrance trench. Another technique consists in the pumping of interstitial air in the muck with a vacuum truck immediately after each blast.

Jan 1, 2002

By W. L. Saunders, Richard T. Dana

The dynamites are graded according to the percentage of nitroglycerin that they contain. Thus a “40% powder” would be one in which the sticks, weighing one-half pound each, would include one-fifth of a pound of pure nitroglycerin. Dynamite is usually packed in paper cartridges weighing about one-half pound each which will vary in diameter. When ordering, it is customary to specify a size of cartridge that will as nearly as possible fill the drill hole, the commonest size being 1 ¼” in diameter by 8” in length. It is nearly always shipped in 50-lb. boxes, which have a volumetric capacity of 3/4 cu.ft.

Jan 1, 2013

By Ronald Ticona

Generally, the drilling and blasting operation are managed independently to the processing plant outcomes. Therefore, the technical segmentation to determinate the ore drill and blast designs do not include processing plant rock properties such as Bond Work Index, Axb, Drop Weight Index or other. This work describes the case study of a copper mine in Peru, which, together with its strategic partner ORICA, have implemented projects focused on optimizing mine fragmentation. The year 2021, mine operation according to its mine plan would have a significantly increased SAG mill hardness, which would impact directly on copper concentrated production. An integrated strategy from mine to plant has become necessary to maintain the production levels.

Feb 6, 2023

By Joshua Hoffman, Braden Lusk, David McLane, John Rathbun

The research conducted previously on Shock-Tunnel Waveform Analysis gave a brief insight into the propagation of a shockwave within a shock-tunnel compared to that of an open air arena test. As a refresher, a shock-tunnel is an energy channeling device used to simulate the effects of a large scale detonation with significantly smaller charge weights; having the ability to conduct tests in this fashion can greatly reduce the costs of testing products.

Jan 1, 2012

By Thierry Bernard

It was in the 1980s that USBM published one of the first regulations to protect constructions from the effects of vibrations caused by mine blasts. Several countries have made their own regulations or recommendations since then with vibration limits that are often lower. However, on many sites, operators choose vibration limits that are lower than those of the existing standards, in order to limit the number of complaints received. The real question is how can we know what level of vibration is susceptible to create or worsen an existing crack in a construction. MCM, to the north of Quebec, is working a deposit on the periphery of the town of Malartic. Within the scope of its environmental monitoring programme, together with the joint monitoring committee, MCM has equipped four sample houses for over 18 months, in order to learn if there is a relationship between the evolution of damage to existing constructions and the seismic levels of vibrations created by mine blasts. The publication presents the results of this unique study that has analyzed millions of measurements (seismic, extensometric, and temperature) to define what relationship exists between the levels of vibration and the movement of cracks. Some surprising results versus some published previously (see ref) might change our perception of the subject.

Jan 1, 2018

By Sushil Bhandari, Amit Bhandari

In this paper, a case study is presented of a large global cement company using a cloud and mobile based platform across 17 of their mines consistently over a large number of users over a period of over two years. The use of a blast platform is detailed which include blast designs, blast data collection and the trends in terms of results.

Feb 1, 2020