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By Dale S. Preece, Stephen H. Chung

Electronic detonators and the attendant precise detonation timing that they facilitate are having a measurable effect on rock blasting in terms of improved fragmentation and vibration control. These improvements are increasingly well documented which is driving the expanding use of electronic detonators. In spite of the growing body of positive evidence concerning the benefits of precise delay timing, very little work has been done to document the impact of electronic detonators on the movement of rock. In this study 3-D computer programs, used to predict blasting induced rock heave, including the effects of detonation timing, are used to simulate the effect of precise timing on rock movement. Implementation includes quick, precise timing between blastholes going down a row and then much longer delays between rows of blastholes. For example an effective blast design might call for precise 3 ms delays between blastholes along a row and then 60 or 72 ms between rows. Several options are studied in this paper using computer simulations to draw some conclusions about the underlying physics affecting the process and how precise timing might have a positive impact on blasting induced rock motion.

Jan 1, 2005

By Robert Martin, Brian W. Stump, David P. Anderson, W Scott Philips

Since 1994, various mines in the US have cooperated with research scientists at the Los Alamos and Lawrence Livermore National Laboratories to address issues related to verification of the Comprehensive Test Ban Treaty (CTBT). The .CTBT requires that no country may conduct any nuclear explosion in the future. While the CTBT is a significant step toward reducing the global nuclear danger, verifying compliance with the treaty requires that the monitoring system be able to detect, locate and identify much larger numbers of smaller amplitude seismic events than had been required previously. Large mining blasts conducted world-wide will be of sufficient amplitude to trigger the monitoring system at the lower threshold. It is therefore imperative that research into the range various blasting practices employed, the relationship of yield to seismic magnitude, and identification of anomalous blasting results be performed. This paper will describe a suite of experiments funded by the Department of Energy and conducted by the Los Alamos and Lawrence Livermore National Laboratories in cooperation with the US mining industry. Observations of cast blasting, underground long wall generated coal bumps, stoping, and explosively induced collapse of room and pillar panels will be presented. Results of these dual use experiments which are of interest to the mining community will be discussed. These include 1) variation of amplitude of seismic energy at various azimuths from cast blasts, 2) identification of the extent of back failure following explosive removal of pillars, and 3) the use of single fired shots for calibration of the monitoring system. The wealth of information and discovery described in this paper is a direct result of mutual cooperation between the US Government and the US Mining Industry.

Jan 1, 1997

By Richard R. Marston, Scott Herr, Steve Pries, Donald L. Jr Ewart

The purpose of this paper is to identify and examine alternative methods (other than shovel/truck stripping) of effecting the pre-stripping of consolidated overburden, in conjunction with dragline stripping operations, at surface coal mines. The analysis will be case study oriented with practical mining considerations and comparative economics being evaluated. Alternatives that will be examined include blast casting, dozer push, and multiple pass dragline sequences.

Jan 1, 1992

By Robert Boehnke, Bernd Mueller

Despite enormous efforts over the last decades there are still many unanswered questions with respect to calculation and modeling of the blast process using appropriate physical laws. Most calculations of explosive charges of a blast design are based on experience, empirical observations or blasting theories with serious shortcomings. This paper presents a new theory for the design and calculation of a rock blast that is based on the momentum. It offers a clear-cut method for the calculation of blast processes. The theoretical results will be compared with on-site measurements by means of a newly developed strain sensor and further measuring equipment. The momentum theory helps better to explain physically the processes of a blast. On the basis of long-term statistical investigations a momentum balance can be carried out with the volume-based blasting momentum and the measurable momentum associated with the muckpile and the remaining rock mass. This type of consideration requires a complex procedure which includes the blastability of the rock masses. Realis tic strain measurements open a new interpretation possibility and judgment criteria for the most probable building damage, the dynamic impact on general types of buildings and also for the blast process itself. The blast-induced stress and the momentum generated could be back-calculated using a geophone profile and the strain sensor. The strain owing to a dynamic impact can be influenced by the changing of the drill-, blast- and shotfiring technique like the until now measured vibration velocity. In this way it is possible today to make a complex preparation, calculation and evaluation of blasts. The new techniques of measuring in connection with the momentum theory bring about an increase of the safety and a clearcut method of improving the blast processes. This procedure offers new possibilities for the precise calculation, simulation and modelling of blasts and resulting vibrations and leads to an increase of the safety as well as economic adaptation of the drill-, blast- and shotfiring techniques to a pre-determined blasting result.

Jan 1, 2003

By Tom Short

"Construction blasting covers a very extensive variety of explosive applications. I will discussseveral of these with you and then show slides from my collection, starting in 1956, which will betterillustrate the types of blasting under discussion."

Jan 1, 1991

By William Hustrulid

Pre-split blasting is a primary technique for creating slopes with a minimum amount of unwanted damage to the remaining rock mass. Rock slopes created in such a way have both safety-related and economic advantages. The applications extend from road cuts to rock quarries to large open pit mines. For example, as deep open pit mines approach the end of their operating lives, slope steepening is one option to be considered. To be able to safely achieve and maintain steepened final slopes, good blast design techniques must be available and applied together with close operational control. Pre-split blasting is an important element in this slope creation process.

Jan 1, 2007

By A B. Opperman

For many years explosives energy has been utilized in mining and construction as well as many other applications which are vital to our way of life. Many types of explosives have made their contribution as technology has moved forward. One of the best known was dynamite, which for many years was the mainstay of explosives users. Although dynamite had many advantages over its predecessors, it had the principal shortcomings of being somewhat hazardous to handle and was known as a headache producer.

Jan 1, 1975

By J Deen, P Sterk, W Forsyth

Homestake Mining Company has made a firm commitment to develop a functional and cost effective perimeter blasting program. The goal of the program is to develop smooth, sound walls in all development ends. A good perimeter blasting method will improve safety, reduce waste rock handling, allow easier support installation and reduce scaling time. All the benefits will contribute to an overall reduction in total development costs.

Jan 1, 1997

By Fumihiko Sumiya, Hideki Hamashima, Shigeru Itoh, Shinya Tanaka

The detonation characteristics of non-ideal explosives, especially the emulsion explosives, are critically affected by the confinement of case. In this study, we focused the shock wave propagating in case as confinement factor. Therefore, the objective of this study was to obtain a better understanding of the influence of shock wave propagating in case on the detonation characteristics of explosives in laboratory scale.

Jan 1, 2007

By Yoshikazu Hirosaki

How big or small is the Japanese explosive market? Who are the major explosive customers? Is there any big construction project in which a large amount of explosives is expected? What is the future of the explosives industry in Japan? Is it true that there are no ANFO trucks? What is the licensing system for blasters? Is there any education system for blasters?

Jan 1, 2001

By James W. Reil, Douglas A. Anderson, Steven L. Burchell

A total of 26 full-scale production blasts at three sites were extensively monitored with sophisticated instrumentation systems to determine the benefits of "ore. accurate detonators. The new and "ore accurate MS electric Masterdet detonator was tested against conventional detonators to determine any increase in productivity outputs. All blast design parameters between paired blasts were kept as constant as possible with the only difference being the inherent accuracy of both detonator systems.

Jan 1, 1989

By Don W. Lake

Of all the blast monitor& instrumentation systems and techniques av&able today, highspeed photography and videography remain as the most valuable, stand alone, diagnostic techniques to evaluate full scale blasts in the mining and explosives industries. Highspeed image data, coupled with information from other instrumentation systems, such as continuous VOD records, seismographs, laser surveying systems, refraction seismographs, etc. can eIiminate many assumptions about what actually took place in a blast. Thus, diagnostic confidence in evaluating both good and bad blasts is increased, and optimum blast designs are achieved considerably faster when compared to the trial and error approach or relying on just the experience factor.

Jan 1, 1992

By John Watson, Jay Rodgers

The world of blasting and explosive use continues to evolve into one which relies heavily on measurement, quantification, process control, and information feedback as a means of contributing to operational improvements. More than ever good blast performance, once thought to be a result of someone’s “artistic ability”, is giving way to “hard science” and measurement techniques. Variability in product performance and process control is becoming less tolerable with increasing environmental issues, regulatory pressure and public awareness.

Jan 1, 1998

By Wang Hong Qu

This paper observes the shape of throw explosion crater its ejecta locus of internal medium and the process of distance along with slope's angle developing. It was discovered that initial velocity is inversely proportional to slope's angle. The velocity of surface distribution at the lower half crater of explosion is larger than at upper one. It carries the relevant calculated formula and physical process of explosion crater forming under the inclined boundary conditions, and some important law. It proved that the gravity influence is very distinct for the blast action in the little resistance line.

Jan 1, 1991

By M. Hagfors

Underwater explosions have been used several decades for the determination energy content of explosives. It’s the only test method by which shock and gas heave energy values can be determined separately. The total energy is a sum of these two partial energies. This test method enables us to develop explosives for different purposes; the military high explosives should contain more shock energy whereas the gas heave energy is a very important feature for the blasting explosives. The method also enables us to observe the changes and to adjust the energy content of an explosive as a function of increments of one or more energetic component.

Jan 1, 2006

By Randall M. Wheeler

"Fourier analysis is a very powerful frequency analysis tool. However, it is frequently misunderstood and sometimes used inappropriately. Part of this workshop will involve the basics of Fourier series, the Fourier integral and finally the Fourier transform. Included will be a brief discussion of analysiswindows, including the box and Hamring windows."

Jan 1, 1998

By V. A. Akinbinua

This work is intended to examine the relationship between rock fragments produced during compression tests using a soft testing machine, e.g. hydraulic press (the machine used in this work is Amlser rock testing machine), and the rock fragments size distribution produced by fragmentation of the same rock through application of explosive. The rocks tested are fine grained marble, medium grained tonalite and fine-medium grained granite, medium grained norite and medium grained gabbro. The rocks types are prepared according to ISRM methods to be tested for strength determination. The rocks are loaded at constant load until failure. The fragments resulting from the failure of each of the rocks types are collected for size characterization by sieve analysis. The same rocks tested under soft testing machine are also prepared into blocks of dimension 150 mm length x 100 mm width x 100 mm height for blasting by explosive application. Each block of the different rocks are drilled through with an 8 mm diameter drill to a depth of 80 mm. Each of the holes on the blocks is spaced from each other at 44.7 mm and with a burden of 28 mm. The holes therefore formed a rectangular blasting pattern. Each of the holes was charged with a 720 mg electronic detonator and fired instantaneously inside a cylindrical blasting chamber. After each shot, the fragments are collected for size characterization. The sizes distributions from blasting are compared with sizes distributions resulting from rock testing using the parameter Xc of the Rosin-Rammler distribution function (RR) and 75% cumulative percentage passing. The analysis and finding from this work is presented in this paper.

Jan 1, 2014

By C. Pelley, S. Kelebek, P. D. Katsabanish, M. Pollanen

A series of small scale tests have been conducted to evaluate the effect of blasting on the grinding resistance of rocks. The samples consisted of homogeneous blocks of granodiorite and limestone while blasting was performed using single and multi hole configurations. Grinding resistance was evaluated using relative ball mill tests, rod mill tests and the SAG Performance Index test (SPI) developed by Minnovex. It was shown that the grinding resistance was affected by blasting. However the effect depended on the final product size. In the case of the coarse grained granodiorite, a negligible effect was observed for grinding below the natural grain size of the rock, while the fine grained limestone exhibited more significant changes, in the range of 13-16%. Grinding of granodiorite in the coarse size range indicated a general reduction of its work indices, as evidenced by the results obtained from the ball mill, the rod mill and the SPI tests.

Jan 1, 2004

By Quentin Rhoton

To benefit two endangered fish species, waterfowl and other wildlife, and water quality in the lake and downstream, the decision was made to remove levees that had been in place since the 1950s. Because the levee material was mainly dredged up lake bottom peat, it was decided to pare down the sites chosen for breaching with dozers and trackhoes. This material was spread out onsite instead of expensive removal by dumping elsewhere. Because of the instability of the final pared down levees and the lake level being at a ten-year low, it was decided to use explosives to breach four of the sites. After over five months of earthmoving and two weeks of loading holes, the levees were detonated the day before Halloween, 2007. Somehow pumpkins showed up to be part of the explosive activities.

Jan 1, 2009

By Douglas Anderson

Even though there is always a feeling of anticipation before a blast is detonated, most blasts are part of a day’s work. Once in a while there is an event that impresses even the most jaded blaster. Few blasts have had the impact of the Kingdome implosion in March of this year. Fortunately for both the Seattle area and the explosives community, the “impact” of the implosion was far less than many local residents had feared. This outcome, of course, was not by chance, but the result of careful planning and design. An urban implosion requires a mix of engineering, logistics, and public relations. Unique challenges on this project tested the resourcefulness of the entire team.

Jan 1, 2001