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By Michael E. Curtis

This paper outlines a study performed to analyze the advantages of utilizing a blasting agent with a velocity of detonation that is 1.3 to 1.4 times the P-wave velocity of sedimentary shales and sandstones at a major Midwest coal operation.

Jan 1, 1997

By J. Meissner

In this paper vibratory crack response is compared to that produced by volumetric changes in foundation soils induced by natural events. These natural phenomena include changes in the water table, changes in soil moisture, and formation of ice lenses to name a few. Previous papers have compared vibratory responses of cracks to atmospheric effects such as those produced by the passage of weather fronts and daily changes in temperature and humidity. Periodicity of these atmospheric effects is on the order of a day to half a dozen days. Thus it is possible to observe atmospheric effects with measurement over a period of weeks to several months. On the other hand, crack response produced by volumetric changes in foundation soils occurs over a period of many months and/or may be seasonal in nature if not longer in the case of drought. Thus its measurement requires long periods of observation (many months to significant fractions of a year) or observation during critical seasons. Since it occurs over long periods of time, its observation may be obscured by climatologically induced crack response. These soil volume changes are compared with climatic data to describe the correlative nature of crack response in time with the soil volume change phenomena and likely climatic causes.

Jan 1, 2009

By Albert van Niekerk, Mick Lownds

Overview of the UNI Tronic™ Electronic Blasting System

Jan 1, 2004

By Serge V. Krasvin

The excavation of large amounts of ferrous and non ferrous metals, coal, shale, and other minerals - requires intensification of blasting techniques. In the late 80s in the USSR, the annual consumption of explosives reached more than 2.7 ml t., the great bulk of which consisted of granulated and powdery explosives. Nevertheless, slurry explosives, due to lower costs and better blasting characteristics, are gaining a stronger position in the explosives market.

Jan 1, 1992

By Chantale Doucet, Yves Lizotte, Alan Cameron

A joint Federal Government-Industry research project on the effect of geology on the fragmentation of rock excavated by blasting in underground developments was conducted at the CANMET Experimental Mine, near Val d’Or, Quebec. A total of thirteen (13) blasts were studied from November 1994 to February 1995. The analysis of each blast was divided into three stages: pre-blast characterization, including structural mapping, assessment of Rock Mass Ratings (RMR), Tunneling Quality Indices (Q), blast design documentation; blast characterization comprising blast vibration monitoring and analysis; and post-blast assessment comprising fragmentation assessment by digital photoanalysis, calculation of half cast factors and measurements of bootlegs.

Jan 1, 1996

By G Alan Foster

Many complaints generated from blasting operations result from the marked human response to ground transmitted vibrations and air blast effects and so many authorities have considered the regulation of blasting in terms of human response rather than, as previously, in terms of preventing damage to structures.

Jan 1, 1981

By Roger L. Keller

This paper covers the design and test blast procedures for several drop shafts and edits leading to the completion of a recent Rochester Pure Waters Expansion Project . Due to the projects "in-town" presence, and its close proximity to many sensitive vibration sites, very stringent ground vibration limitations and guidelines for blasting were places on each site.

Jan 1, 1991

By Dennis Dobson, Keith M. Henderson

Lone Star Industries, Inc. in Cape Girardeau, Missouri operates an open pit mine to produce limestone for its portland cement manufacturing plant. The present mining method, for safety and legal reasons, requires a set back from the property line, a berm, sloped overburden, and vertical rock walls with catch benches.

Jan 1, 1997

By Thomas E. Ricketts

An important part of underground mine planning and operations involves the reclamation of working areas after blasting before the mining cycle can continue. This is especially true for mining that must use large blasting operations in the vicinity of extensive underground workings. In an effort to develop a rational procedure for estimating mine damage produced by blasting, underground rock fall has been assessed for a large-scale blasting operation in oil shale. The amount of mine damage has been quantified in terms of manshifts of effort required to reclaim underground working areas after blasting. This has been further broken down into the three main phases of reclamation, i.e., scaling and excavation, rockbolting, and miscellaneous repairs on ventilation, utilities, etc. Different types of openings have also been assessed including level tunnels, incline drifts and rooms. The effect of repeated blasting on mine damage has also been documented with initial blasts producing more damage than subsequent blasts.

Jan 1, 1988

By Jeff Friedman

This paper addresses certain problems to be encountered when a blasting contractor agrees to provide indemnification. Nearly 100% of all blasting work is performed pursuant to a contractual agreement. Whether the explosives engineering firm works directly for the property owner, or for a general contractor by way of subcontract, indemnification agreements are generally required to protect owners, operators, general contractors, and other interested parties in the event there is subsequent litigation. These contractual requirements are typically referred to as indemnification and “additional insured” agreements. We will address the ramifications of contractual indemnification as well as “additional insured” agreements in this presentation. Some of the aspects of this paper will include:

Jan 1, 2004

By E Castelli, M Fomaro, R Mancini, M Cardu

The economic return of rock blasting is not provided by brute volume of broken rock, rather by the amount of marketable product. That is the case of the porphyry quarries of Trento district, whose output is mainly absorbed by road paving and building facing elements production.

Jan 1, 1995

By U Nyberg

Peak particle velocity (PPV) and distance measurements from a single-charge blast test conducted by Swedish researchers in iron ore at the Kiruna Mine in northern Sweden are presented. They are used along with theoretical PPVs calculated using an equation based on hydrodynamics to determine a damage distance range caused by a single charge. This equation, which relates PPV to explosive properties, charge geometry, and distance from a charge, was then applied to a charge of different geometry that was used in drift rounds. A comparison between calculated and measured PPVs suggests that the stoping holes likely damage the easer hole locations, and the easer holes produce damage to the perimeter hole locations. The practical effect is that typical damage limit predictions based on measurements conducted in fresh or undamaged rock are conservative. This suggests that even when perimeter control is not exercised in drifting (i.e., the perimeter holes are fully loaded), the resulting damage may be less than normally expected due to the wave damping effect of the pre-damaged rock. Due to the damping effect, poor perimeter blasting practices are somewhat self correcting. However, it must be strongly emphasized that well-engineered blast designs with perimeter control are highly beneficial in relation to both economic and safety aspects.

Jan 1, 2011

By Robert E. Miller

Mass blasting of open stopes and pillars is a normal operating practice at Isa Mine. Three main parameters are used to classify the types of mass blasts. These are type of explosive used, blasthole diameter and system of initiation. Both electric and non-electric initiating systems are currently employed. The advantages gained by large firings are many. More efficient utilization of manpower, due to the concentrated and continuous charging, is achieved. There is no requirement for men to re-enter areas where localised ground conditions may have deteriorated and exposure of ringfirers to stope voids is reduced.

Jan 1, 1980

By Ruilin Lang

This paper presents an application of 3-D plots and non-linear regressions to define a sitespecific form of the charge weight scaled distance. The PPV (PPA) of single hole blasts is normally considered as a function of two independent variables - the charge weight and the distance. It is of great importance to obtain the relationship of the function accurately for a concerned site in terms of blast vibration analysis and modeling. However, in pre-computer time it was difficult to plot 3-D graphs. Consequently, a charge weight scaled distance was used to plot the PPV (or PPA) against the scaled distance as 2-D graphs. Blast vibration investigators use several forms of the charge weight scaled distances to plot data. We can exemplify them with the cube root of charge weight scaled distance, the square root of charge weight scaled distance, and other forms (Hossaini and Sen, 2004). Each of these scaled distances assumes relative contributions of the charge weight and the distance to the vibration attenuation. For example, the charge weight is assumed to have a less contribution to vibration in the cube root scaled distance than it is assumed in the square-root scaled distance. In reality, for different sites the relative contribution of the charge weight and the distance may be different and site-specific. This may explain that in some cases, the blast vibration data plots using these charge weight scaled distances are scattered. This could be largely due to the fact that the definition of the form of the charge weight scaled distance is not adequate for the particular site condition.

Jan 1, 2006

By Michael S. Wieland

This report discusses measurement techniques utilized in and trend results obtained from research on delay blasting malfunctions in underground coal shots at the U.S. Bureau of Mines. Charge malfunctions occur during delay blasting in underground or surface mines, rendering the explosive operations more hazardous and less productive. Modern instrumentation techniques reveal several types of reduced charge performance, resulting from cross-hole interactions. Two receptor (wave-target) charge malfunctions were detected in fourteen shots that were undeniable. There were other receptor charges that exhibited under-performance by registering out-of-tolerance or noticeably reduced detonation rates. Delay blasting generates tremendous shock waves and rifting forces that fracture and heave the surrounding stratum and unfortunately damage remaining unfired charges. This report contains two graphs, representing roughly 1% of total records, that show donor (wave-source) charge shock waves and rift (reaction-to-heave) compressions. These debilitating wave impacts precipitate modes of reduced charge performance ranging from weak detonations or misfires to sympathetic detonations. As recognized from previous research, impaired charges react poorly, perform less useful work, and yield fumes with atypical higher toxicity.

Jan 1, 1995

By M Lemieux, R Mason

The SABREX blast modeling program was introduced to I.O.C.C.'s Carol Lake Iron Ore Project in December 1987. As part of CIL's Technical Services, SABREX was used to implement an optimization program designed to analyze and introduce various grades of MAGNAFRAC at a constant pattern while maintaining acceptable blast results.

Jan 1, 1989

By Brian Stump, D. Craig Pearson

This work quantifies seismic coupling as a function of charge weight for single-fired (simultaneously detonated) explosions observed in the mine and at regional distances. These single-fired explosions are contrasted to standard production shots from the same mine. Production shots include cast blasts to remove overburden and coal shots for fragmentation. The blasts were conducted in a mine in NE Wyoming. The data sets consist of measurements in the mine (100-10,000 m) and at regional distance (360 km) using a seismic array near Pinedale, Wyoming (PDAR). The single-fired explosions ranged in designed size from 5,500 to 50,000 lbs. Peak amplitudes measured at a single element of the regional array are modeled by a power law relation dependent on explosive weight. Scaling constants were determined for each of the dominant regional phases: b(Pn) = 0.84±0.14; b(Pg) = 0.84±0.09; b(Lg) = 0.91±.08. Spectral ratios of observations from different explosions observed at the same station illustrate the frequency dependnce of the source scaling relations. Spectral ratios of in-mine observations are consistent with those of regional data. The observed single-fired ratios are well replicated by Mueller-Murphy source model ratios. The data and model illustrate both the increase in long-period spectral level and the accompanying decrease in source corner frequency with increasing charge weight. The coal and cast blasts that make up the production shots ranged in size from 77,000 to 4,738,230 lbs. The peak amplitude (1-20 Hz) for the largest delay-fired production shot (4,738,230 lbs.) is comparable to that of the largest single-fired explosion (50,000 lbs.). This comparison can be explained in terms of destructive interference between waveforms from individual boreholes introduced by delay firing. Shot specific models of delay firing suggest that peak amplitudes in this same frequency band for the production shots are insensitive to the total amount of explosives in the blast. Peak amplitude data at regional distances supports his modeling result.

Jan 1, 2002

By Michael Noy

Current image based systems used to measure fragmentation are measuring the two dimensional presentation of a set of three dimensional objects. A two dimensional measurement of fragmentation restricts both sampling and particle size classification and hence provides a different evaluation of the fragmentation to that of a conventional sieve analysis of the same sampled material. Many modern image based fragmentation measurement systems attempt to convert this two dimensional analysis to a three dimensional analysis in order to deliver a "real" measurement of the fragmentation distribution. This paper questions the necessity and validity of this transformation and lays down the framework for the establishment of a standard in fragmentation measurement based on a two dimensional analysis. The results of image based measurements of laboratory prepared samples indicate that differences in mass distributions (3D distribution) can be mapped by an appropriate image based analysis which provides area versus particle size information.

Jan 1, 1997

By Y. Hirosaki, H. Hamashima, Y. Itoh Kato, S. Tanaka

The emulsion explosives show non- ideal detonation behavior, and its detonation velocity can be controled by selecting the size and adjusting the quantity of voids involved. To establish the technology to control the detonation characteristics of the emulsion explosives, some experiments have been carried out using resin balloons of five different sizes ranged from O.OSmm to 2.42mm in the average diameter. Detonation velocities of the emulsion explosives containing resin balloons of different size and quantity were determined for the charge diameter of 20-50mm. The detonation velocity at infinite charge diameter was compared with calculated ideal detonation velocity. The emulsion explosives containing large (0.5mm or larger) balloons showed big discrepancy between the measured and calculated detonation velocities, and the fraction of ammonium nitrate reacted in the reaction zone was estimated to be significantly low. It was shown that the reaction zone length was proportional to the size of voids involved. The critical charge diameter was determined for the emulsion explosives containing different resin balloons at the various explosive densities. It is large for the emulsion explosives containing large voids, and it was shown that the critical diameter is proportional to the distance between the void surfaces, not to the void spacing, the distance between the centers of the voids. The reaction rate of the bulk emulsion matrix seems to be the major factor that affects the critical diameter than the specific surface of voids. Good relationship between the critical diameter and the reaction zone length was observed.

Jan 1, 2000

By G Alan Foster

The presence of approximately 600,000 attorneys in the U.S.A. and the determination by the courts that blasting is considered an 'ultra hazardous' activity makes every practical blaster aware that at some time during his working life he will probably be faced with defending himself in court.

Jan 1, 1982