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By Terri Jordan, Kenneth Hollingshead, Mary Jo Barkaszi

The Port of Miami, Miami-Dade County, Florida (Port) is the largest container port in the State of Florida. However, it is located in the center of a diverse ecosystem. Biscayne Bay surrounds the Port and portions of the bay have been designated as a National Park, a Florida Aquatic Preserve and a state Critical Wildlife Area. The bay is home to many protected, threatened and endangered species including the Florida manatee, five sea turtle species, American crocodile and bottlenose dolphin, in addition to important recreational and commercial fish species.

Jan 1, 2007

By R L. Keller

Hong Kong has some of the most restrictive practices regarding blasting than any place in the world. Regulations regarding vibration limitations are 1 in/sec for structures and 0.5 in/sec (or even less) for most utilities; with no recognition of frequency response or adjustment. The Hong Kong Geotechnical Engineering Office has one of the most conservative approaches and protective guidelines for pre-blast assessment of slopes subjected to blast vibration (SEE paper '96). The protective measures to control flyrock generally required by the Mines Division are additionally very stringent. It is not uncommon for the costs associated with protective measures or methods which must be employed to exceed the cost of the drilling and blasting itself - or to waiver blasting application unfeasible altogether. From these restrictions it can easily be imagined how blasting in this urban environment would be most challenging.

Jan 1, 1997

By K. Dufresne

Blasting in geothermally high temperature ground and/or extremely reactive ground is an increasing common challenge for surface and underground mines. Many current PETN based non-electric and electronic detonators have manufacturer published in-hole temperature limits ranging from 55°C to 65°C (131°F to 150°F). When confronting blasthole temperatures above the manufacturer published limits, operations may request site-specific guidance and qualification for use. The advised safe loading window for in-hole PETN based detonators is often too short to be practicable for production blasting. To overcome limitations of PETN based initiation systems, surface mines with high temperature ground and/or reactive ground are known to load blastholes with a qualified high temperature bulk emulsion that are top primed with a cartridge of temperature qualified detonator sensitive emulsion plus an RDX detonating cord downline. As there is no in-hole delay detonator in this system, blasthole timing is accomplished with surface delays. Although this system is safe, top priming and surface delaying does influence floor quality and top size fragmentation, and safe loading windows times reduce blast block size and increase blasting frequency. A mining company with a site characterized by geothermally high temperature ground plus highly reactive ground employed a blasting system like the one described above. The site desires to improve blasting performance by moving to an in-hole delay initiation system that can withstand the site ground conditions. At the request of the mining house, DynaEnergetics (hereafter “the company”) developed an electronic initiation system for application in geothermally high temperature ground and/or extremely reactive ground conditions. The DynaEnergetics IGNEO high temperature electronic initiation system is rated for in-hole use in ground up to 150°C (302°F) for 48 hours. The detonator consists of a high strength detonator with an HMX base charge and thermally resistant downline. To make up a primer, the detonator is inserted into a booster charge assembly that is fitted with a small HMX shape charge. This high energy primer is designed to be compatible and reliable for firing bulk emulsions, including those with high percentages of urea inhibition to combat reactive ground. Up to 1000 detonators may be programmed in 1ms increments up to 1500ms. The system is controlled by a digital firing panel that can be used with either a wired or wireless trigger. The system enables high temperature and/or reactive ground sites to utilize in-hole delay initiation and realize the associated performance benefits

Jan 1, 2024

By Peter Cameron, Tom BoBo

Comminution, being the energy intensive part of a mining operation receives much scrutiny by cost controllers, CEO’s, investors and others as the mining industry goes “back to basics” to reverse the decline in productivity which occurred during the mining super cycle.

Jan 1, 2019

By M. Khaled, K. Abdel Rahman, M. Khattab

Helwan limestone quarry is located at a distance of 35 km (21.7 miles) to the south of Cairo downtown. Drilling and blasting operations are used to extract the limestone for the Helwan Cement Company (HCC). In 1980’s a new urban community was constructed adjacent to the quarry. This situation led to shifting of the old quarry 5.0 km (3.1 miles) to its current location, to avoid causing blasting problems to the new community. Unfortunately, the new quarry is opened in a highly faulted area, with weak zones of brittle materials. The drilling and blasting crew is facing many difficulties due to the geological complexity along these zones. Moreover, the extension of this community towards the new quarry makes the control of ground vibrations is very important.

Jan 1, 2008

By Karl Peterson, Bibhu Mohanty, Chanakya Nariseti

The mechanism of crack formation in two target rocks (Kuru granite and Flamboro Limestone) is studied experimentally by simulating the impact action of a percussive drilling bit. Rock samples are dynamically loaded using a custom made impacting bit (8 mm, 12 mm and 15 mm diameter bits). The target rocks are impacted at velocities 8, 10, and 12 m/s. The resulting crack patterns are visualized by three techniques, Dye penetration, CAT scans and Optical scans. Mapping of the crack patterns is manually done with Photoshop. For 3D damage visualization, the crack patterns are mapped in two planes (impact surface and longitudinal sections). The three techniques are compared to determine an optimum technique for better damage visualization. The evolution of crack pattern with impact velocity and bit diameter is discussed.

Jan 1, 2015

By K Lombardo

Numerous small- and intermediate-size cratering experiments have been conducted in Piceance Creek Basin oil shale at the Colony and Anvil Points oil shale mines near Rifle, Colorado. The purpose of these experiments was to evaluate scaling as a tool to infer the behavior of large-scale tests from small-scale experiments, to calibrate the hydrodynamic computer codes used to model explosive fragmentation of oil shale, and to investigate the influence of bedding plane orientation, natural joints, fractures, and the grade of oil shale on rock fragmentation.

Jan 1, 1983

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.

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

Feb 1, 2020

By Mathias Jern, Ruilin Yang

A blast vibration model has been developed that simulates effects of almost all blast design parameters on the blast vibration peak particle velocity (PPV) from a production blast with multiple blastholes at a given point of interest in the rock. The velocity of detonation (VoD), initiation points, explosive types (density, VoD, energy), charge decoupling, and decking in each blasthole are simulated along with other blast design parameters. The information from signature hole blast vibration and the blast design are the input to the model. The model can be used to assess blast damage in proximity of blastholes as well as far field vibration PPV.

Jan 1, 2019

By Dave Weymer

Falling timber in BC has always been a hazardous job. Huge, often rotting trees and steep, rugged terrain combine to create difficult and dangerous conditions. Death and injury rates are among the highest of any occupation in North America. In BC, the men that head out, saw in hand, are called fallers.

Jan 1, 2013

By John W. Kopp, David E. Siskind

Over 4 billion pounds of commercial explosives are used by the U.S. mining industry every year with an excellent and improving safety record. However, accidents involving explosives are seldom minor. They produce a disproportionate amount of fatalities compared to other mining activities, as reflected in the relatively high severity rates. The U.S. Bureau of Mines (USBM) has been analyzing blasting accident data obtained from the Mine Safety and Health Administration (MSHA) to determine the most frequent causes of mine blasting accidents, examining trends in these accidents, and identifying areas of needed research. This paper is an update of three previous blasting accident studies conducted on 4-year intervals by the USBM and published in 1983, 1987, and 1991, and is based on a total of 869 blasting accidents.

Jan 1, 1995

By Michael S. Wieland

"This report investigates whether it is tractable and thereupon reasonable to remove the boosterinfluences when ranking the toxic fumes of non-cap-sensitive mining explosives. The hazard potential is represented by relative fume toxicity RFT, the resultant influence computed from a formulated rule with a restricted set (tally) of fume components and multiplying constants. The RFT result is compared to the rule criterion that represents the worst case tolerable toxicity stipulated by regulations or otherwise. The typical nonstoichiometric booster composition can render notable unwanted influence on the RFT ranking results. Historically, the remedy was to shoot the booster separately and reduce the trial concentrations by the relevant subtractions. Unreal negative concentration results were noted on rare occasions, revealing the faulty nature of the reduction procedure. With thermodynamic reaction chemistry codes TDRC, on the other hand, the booster ingredients can be retained in or removed from the reactant tabulation, yielding reduction factors taken as the concentration ratios for the two circumstances. The underlying presumption regarding reduction factors is that the ratios of component concentrations with and without the booster ingredients when resolved theoretically ought to equal those rendered experimentally, when tractable. Upon rearranging the presumed relationship, the unadjusted fume concentrations divided by theoretical reduction factors yield the wanted readjusted fume concentrations, thereby removing the booster influence without generating unreal negative concentrations."

Jan 1, 1999

By Calvin J. Konya

There have been many different brands of high precision caps introduced on the US market in the last five years. High precision timing definitely effects the performance of the blast. One should be able to optimize fragmentation and minimize environmental effects with the use of high precision caps and selection of the proper time period. The consumer who purchases the caps may not be fully aware of the tolerances in firing times of caps used in the field. This paper will discuss results of field tests of cap tolerances from an independent study conducted by Precision Blasting Services.

Jan 1, 1989

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 Thomas H. Kleine, Alan R. Cameron, William W. Forsyth

In general the software required by a blast designer includes tools that graphically present blast designs (surface & underground), can analyze a design or predict its result, and can assess blasting results. As computers develop and computer literacy continues to rise the development of and use of such tools will spread.

Jan 1, 1995

By Paulo Couciero

Since explosives are the source of all energy used for rock blast fragmentation and heave, multidimensional effects in the detonation driving zone become essential to better describe the detonation process. In order to use the explosive as an energy source-information for more realist blasting performance simulations, a simple and effective modelling strategy is desirable. Facing this challenge, an engineering approach to two-dimensional unconfined non-ideal detonation is proposed. Based on the elliptical construction of the shock locus, the model combines the axial cylindrical stick Q1D solution with some additional limiting conditions to determine the sonic edge of the charge. For a given set of rate law parameters and velocity of detonation, a complete axial solution is firstly computed through the Q1D model. From this solution, a vital relationship between the axial shock curvature with the shock shape parameters can be stablished. Once this relationship is found, the problem simply reduces in finding the shock shape parameters subject to the sonic edge condition. As a result of this calculation, the corresponding charge diameter can be found. Consequently, the proposed model can map the diametereffect curve by relating the unconfined velocity of detonation with its corresponding diameter. Finally, because of its low computation cost, the proposed engineering approach can be also used for characterizing the rate law parameters by fitting to data from unconfined detonation experiments

Jan 1, 2019

By Julia Creasey, Natalie Hodgson, Claire Ward, Craig Davies, Helen Sarginson

"Emulsion explosive producers are attempting to lower the cost of emulsion production by using lowquality ammonium nitrate in emulsion formulations. Low quality ammonium nitrate contains additivessuch as anti-caking agents and crystal modifiers which contaminate the emulsions causing instability. This presents a need for an effective emulsifier that will maintain emulsion stability under thesechallenging conditions."

Jan 1, 2017

By F. Malek

An extensive blast monitoring program has been carried out to study explosive performance and the effectiveness of blast designs in production blasts in a deep underground mine. Comprehensive monitoring of blasting vibrations through multi-station high-capacity high-frequency accelerometers, and borehole deformation history have been the main tools of such analysis. The mining activity involves relatively unstressed stopes as well as highly stressed stopes. More than 30 production blasts have been monitored, and the respective vibrations from close-range as well as distant seismic stations have been analyzed, and the vibration parameters (amplitude and frequency) have been correlated with explosive charge weight in the holes. It is found that the correlation between blasting rounds and the corresponding vibration amplitudes often have poor correlation for a very significant portion of the blasts. These point to either explosive charge malfunction in those specific blast holes, or inadequate blast design, or the effect of high in-situ stresses, or any combination thereof. This paper analyzes these variables and their effect on the overall blasting operation at the mine.

Jan 1, 2013

By Tyler Acorn, Tristan Worsey

A dozer operator at a surface gold mine accidentally drove a D10 off the side of a highwall. The blade of the dozer caught on the lip of a catch bench 60 ft. (18.3 m), down stopping its descent. The operator scrambled to safety in fear that the dozer would not hold.

Jan 1, 2014