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By Koichi Kurokawa, Takeo Ueda, Yoji Tasaki, Masashi Nakano

We have developed a new firing system which simplifies the handling and extensively increases the safety in electric blasting operations. Based on the principle of the transformer, this system is operated as follows: When a high frequency alternating current pulse (70-110 kHz) is applied to the lead wire and connecting wire (primary circuit), magnetic flux is generated in the transcore, and an induced current flows through the looped leg wire of the detonator (secondary circuit). Then the detonators are ignited by the induced current.

Jan 1, 1986

By Shazad Hosein, Rob Farnfield, Bill Birch, Liam Bermingham

The propagation of a shock wave through air as a result of quarry blasting consists only of one type of wave, the compression wave. This is in marked contrast to seismic waves where a number of different types of wave are generated by the one blasting event. Even so the interaction of the burn time of a single hole and the resulting air overpressure is still too complicated to be able to be accurately modelled from first principles. It is considered that the best way forward is to monitor an individual single hole to obtain a signature wave form that has resulted from this complex interaction. Once this wave form is known, the variation in geometry of a mutli-hole blast and the timings of the successive detonations can be modelled to give a sufficient degree of accuracy to recreate the likely magnitude, duration and wave form of a multi-hole quarry type blast. This can then be directly compared with actual air overpressure wave forms from quarry blast to verify the model.

Jan 1, 2012

By James E. Jr Hargroves

With the ever-increasing population growth and modern trend to urban development, the expansion of utilities is a stable, mad or, and constant source of income for many. Blasting is a "necessary evil" to the utility contractor. It can make or break even the most solvent. Housing development expansion and higher treatment of effluents are causing utilities to appear in more congested areas. This paper discusses some of the aspects of utility blasting in the State of Virginia. Consideration is given to bid procedures, pre-blast surveys, record-keeping and practical application.

Jan 1, 1977

By G Dean Barrett

Just one year ago at the 1986 Annual Meeting of the Society of Explosives Engineers, Dr. Calvin J. Konya presented a paper entitled "Presplitting Granite Using Pyrodex, A Propellant.'' Since that time more evidence has been developed to support the concept that "...gas energy can be the principal splitting force and that the stress wave or shock wave is not necessary to cause the presplitting action to occur." Work done in Vermont and Georgia is presented, and the ability to split granite without causing radial cracking of the bore holes is demonstrated.

Jan 1, 1987

By Shih Wen Wang, Ronald R. Rollins

A blast casting model is proposed to predict the burden velocity in bench blasting. This blast casting model is the first theoretical model that 1) explains the throwing procedures and mechanisms, 2) uses the explosion pressure as the primary source in throwing rock fragments, 3) applies them to field conditions successfully. Also the predicted burden velocities are based on the rock properties, the explosive properties, and the drilling and initiation patterns. This blast casting model is programmed into a computer software "ROCKFRAG". The comparisons between "ROCKFRAG" predicted values and two field test data are in good agreement.

Jan 1, 1992

By Bruce B. Redpath, Thomas E. Ricketts

Scaling laws commonly used for describing or predicting blast motions generated by conventional arrays of blastholes are dimensionally incorrect. The scaling of distance by the cube root of charge weight is correct only for spherical charges, and scaling by the square root of charge weight is incorrect for any charge configuration, although both approaches may result in empirically useful formulas for a limited range of charge sizes. Analysis of motions generated by a large set of underground blasts shows that scaling distance by the square root of the linear charge density, which is dimensionally correct for a cylindrical borehole, yields much more consistent results than the traditional scaling rules. Further, this scaling law is valid right up to the free face of the burden. A significant result of this work is that the peak particle velocity for an array of blastholes is primarily dependent on blasthole diameter and not on total charge weight or maximum explosive weight per delay, which are the commonly used parameters for scaling seismic amplitudes generated by conventional blasting arrays.

Jan 1, 1987

By Rahim G. Haghighi, Calvin J. Konya

Fragmentation is the fundamental concern of rock blasting and it measures the effectiveness of blasting. Fragmentation is sensitive to not only the interrelationship among the design variables, but also is sensitive to local geology. Local geologic conditions have a significant impact on the success of a blasting operation.

Jan 1, 1986

By Changa-Ha Ryu, Hae-Moon Choi, Sang-Don Lee

The rock mass to be excavated is classified using data obtained from the initial site investigation, and the design of excavation and support is then made based on the rock class. Rock classification provides an empirical design with guidelines for tunnel support compatible with rock mass quality and the method of excavation. Although most clients provide standard patterns corresponding to each rock class, the patterns of drilling and blasting have only been used in estimating the excavation cost and not used in the construction stage. The purpose of the study presented in this paper is to establish a standard blast pattern to yield optimum blasting performance along with an attempt to reduce a difference between design and construction. A series of test blasts were carried out at two tunneling sites of Central Inland Highway crossing the country. Long hole blasting was tested in rock mass whose RMR value is over 60. The blasting results were evaluated by measuring degree of fragmentation, advance rate, muckpile distribution, overbreak, etc. Based on the results of test blast, several patterns were proposed for a twolane highway tunnel.

Jan 1, 2005

By Michael A. Barbaglia, Mark William Withey

The lift shot is an essential blast design in the execution of mine creation and expansion plans. Whether it be opening a new quarry, creating a new level in an existing operation, or for control of water, lift shots are utilized to create the desired results. Lift shots by their nature differ from conventional production blasts because they have no free faces for relief of the blast. Due to this fully confined state, the primary direction of the rock movement is vertical, and the potential for excessive vibration and fly rock generation is great.

Jan 1, 1994

By Bruce B. Redpath

This paper reviews empirical and analytical information about window breakage due to airblast. As is the case with damage to structures caused by ground vibrations, a fixed break/no break threshold is inapplicable and window damage must be expressed in terms of a statistical probability. The information is summarized in a graph showing the probability of windows being broken by a given level of overpressure.

Jan 1, 1976

By Joshua Micah Hoffman, Catherine E. Johnson

The recruitment and retention of future talent into the explosives industry is becoming increasingly important. One potential area from which future talent can be recruited is local student chapters. Many of the student chapters are closely connected with engineering programs. While this makes sense and both entities benefit from these arrangements, there is a trend of job placement primarily in the engineering industry. Before the explosives industry can begin to compete with other industries, it should be determined what is drawing the students into these other fields. The work presented in this paper sought to better understand the collegiate student population from which a portion of future explosives professionals will emerge. This was done through the use of an anonymous online survey distributed to the student members of the International Society of Explosives Engineers, as well as, members of SEE student chapters. The survey contained questions about future job and career plans, ideal job placement, and expectations of salary. The purpose of the survey was to determine what these students expect or require from a career in the explosives industry. This information can help steer recruitment activities and job offers. Through understanding what is incentivizing these students who have accepted or plan to accept jobs in other industries the explosives industry can better posture itself to be more competitive in recruiting from the collegiate talent pool.

Jan 1, 2014

By H. Bilgin, Sedat Esen

In this paper, the ground vibrations induced by blasting for stripping work at Sekkoy Open Cast Coal Mine belonging to TKI Yenikoy Lignite Mine (YLI) are investigated and the procedures for monitoring and control of ground vibrations are presented. Ground vibration measurements are conducted in the direction of Turkish Electricity Authorities’ Yenikoy Establishment and social facilities because of the complaints and annoyance arising from this site. Forty ground vibration records are taken in this direction and the vibrations are measured in transverse, vertical, longitudinal components together with peak vector sum. After then the scaled distance relationship is determined at 95% confidence value. Further, Fast Fourier Transform analyses are carried out to determine dominant frequencies for both ground and the structures and amplification factors. When the records taken at four different structures together with the ground are evaluated, it is observed that one of the apartment buildings is amplified the amplitude of longitudinal component 4.3 times. The maximum allowable amount of explosive that can be fired safely at this mine is calculated and recommended on. In the determination of safe amount, 95% confidence line, USBM RI8507 and OSMRE criteria, the dominant frequencies of both ground and the structure, amplification factor and the human response are taken into account.

Jan 1, 2001

By L. O. Souza, J. F. Gewher, M. P. Scussiatto, C. S. Mendonca, R. A. McClure, B. T. Kuckartz, J. Kloeckner

Blasting is the most effective and economical tool available to fragment and move rock for most applications. If properly executed, it can improve down-stream operations such as loading, hauling and crushing. It is not possible, however, to have full control over the energy released by the explosives when a poorly designed blast pattern is used. A poorly designed blast can produce serious damage to equipment and create a potentially hazardous condition to people. Advanced mining technology has been developed to address these potential hazards and optimize the blast pattern. This profiling technology can assist with blast planning and provide quick, precise data about the condition of the rock structure to be blasted. The 3G BlastMetrix system presented here uses three-dimensional (3D) stereo photogrammetry to model the rock mass in a fast, practical and safe manner. Through the image overlapping method, a 3D model is created with thousands of points that provide a significant amount of data regarding geology, geometry and topography conditions. The blasting plan can then be made in a way to optimize the rock fragmentation and avoid areas that could create flyrock. This paper is a case study concerning usage of stereo photogrammic surveying and borehole survey systems in a blasting operation at the Brazilian Quarry, Incopel. One 3D image of a drilled bench was generated using photogrammetry survey technology and the borehole survey data collected using the rodded Boretrak borehole survey system. Utilizing the minimum burden profile reports, explosive loading could be done accurately, resulting in an optimized blast with good heave and fragmentation as well as increased safety.

Jan 1, 2013

By L. Russell Payne

The use of shock tube in the blasting industry is relatively well characterized and understood within the realms to which it is used. Non-conventional uses of shock tube within the EOD and the Aerospace Industry however has not been as widely researched and published. Characteristics of shock tube such as its reliability, simplicity and its non-electric nature make it ideal for functioning or driving mechanical mechanisms, detonators, and timing devices. Outlined in the text are the performance characteristics of shock tube in an array of atmospheric environments including pressures ranging from ambient to 100,000 ft equivalent atmosphere. In addition the useful exit work energy or impulse of the shock tube for driving these various EOD and Aerospace mechanisms is published as a function of tube lengths and atmospheric pressures. Of particular interest to these devices is the required length of shock tube needed to produce the steady state detonation energies and the accompanying properties of the shock tube at these lengths. Various sources publish an arbitrary run distance for steady state detonation and output some where between 20 cm and 1.0 meter. Statistical and experimental evidence with in the text show these numbers to be low and provides an updated reference for shock tubes usage in nonconventional situations.

Jan 1, 2008

By Calvin J. Konya

Many controversies and differences of opinion exist in blasting technology. The primer location in small diameter dynamite columns is an example of one of these controversial areas. It is generally agreed that in rotation firing of small diameter blastholes, primer placement near the bottom of the borehole is beneficial since it reduces the likelihood of cutoffs. The controversy results in the actual location of the primer in the bottom of the blasthole. Some references indicate that the primer cartridge should be the first cartridge in the bottom of the hole, with the cap pointed toward the collar of the hole. Others indicate that performance is improved with no sacrifice in safety by placing a tamped cartridge first in the hole, and the second cartridge being the primer. The following investigation provides some factual data for consideration.

Jan 1, 1980

By S. J. Dillingham

One of the primary goals of every blaster is to achieve the optimum blast design. Too much focus on efficient design, however, can cloud certain issues and exposures that must be addressed if the entire project is to be considered .successful.. Due to the known human response to blast effects and inherent dangers present in the use of explosives, the potential for the project being delayed or shutdown, or the blaster and associated company being named as a defendant in a lawsuit, is always a possibility. Therefore, the blast design and associated project bid must incorporate sound safety contingences and procedures that address those .what-if. Scenarios that may arise as a result of vibration, flyrock, public relations, and job-site personal safety.

Jan 1, 2002

By O E. Jr Crenwelge

Recently promulgated regulations governing blast induced ground vibrations in the mining industry contain a frequency criterion as one option for verifying compliance. This criterion is based upon an oversimplified method which assigns the entire peak particle velocity amplitude to one frequency. Depending upon the nature of the vibration time history, it is possible that this frequency may not even be one of the predominant frequencies of the signal. In addition, the criterion does not specifically define the data analysis approach to be used by the industry for obtaining either the amplitudes or the frequencies of the vibration components. And because personnel in this industry generally have little understanding of vibration phenomena, a number of different approaches are currently being used for satisfying the criterion. This paper presents a method for obtaining both the Fourier amplitude-frequency spectrum and the integrated predominant amplitude-frequency components for the vibration record. The method is both physically and mathematically correct and is in common use in a number of other industries. Therefore, it should be of help to regulators, blasters, and consultants charged with developing, enforcing, or implementing ground vibration criteria.

Jan 1, 1988

By Karl E. Burgher

Accidental explosions occur throughout the world. They can happen at chemical plants, fireworks plants, grain depots, or as a result of collisions involving volatile or hazardous chemicals. It is interesting, as we know as blasters, that we can take two very harmless products and mix them under certain conditions and produce a violent explosion. It is often very difficult for the investigator to determine the magnitudes of blasts after the fact. However, an estimate must be made to settle vibration and airblast damage claims. The blasting consultant or technical representative is often called upon to act as an expert to mitigate these claims.

Jan 1, 1993

By Lon D. Santis

This paper reports on an evaluation of the safety characteristics of short lead, 5 centimeter (cm), Magnadet1 detonators. The Magnadet initiation system uses magnetic induction principles to transfer electric energy from the firing line to the detonator without a physical connection. This study was initiated because the Magnadet initiation system represents a new technology and the Bureau is interested in ensuring that no potential safety hazards are introduced into the nation's mining environment. The Magnadet system and its proper use are described along with a discussion of how it works. The potential hazards examined are: stray current from mine service power, lightning, DC current, static electricity, and radio frequency transmissions. Tip strength is also evaluated. Experiments were conducted to evaluate some hazards and theoretical methods were used to evaluate others. The results showed that the Magnadet short lead initiation system does not exhibit any unusual safety hazards. The new system is at least six times as resistant to common hazards as currently used electric initiation systems, so long as the insulation is intact.

Jan 1, 1992

By Duane Skidmore, Calvin Konya

The supply crunch and cost rise for ammonium nitrate (AN) over the past year have been influenced by a number of factors. These include a general inflationary tendency, particularly great cost rises in fuel, and by a market condition in which demand for ammonium nitrate is great and supply is limited. Demand is largely confined to agricultural and explosives uses with explosives subdivided into mining, construction, and quarrying. The projections show that demand may be expected to increase markedly for the indefinite future in the agricultural and mining sectors of the ammonium nitrate market while fluctuating with indicators of economic activity for the construction and the quarrying sectors. Supply is projected to increase with plants being designed and built due to high need levels and commensurately high profit potential but not enough are planned to provide an equilibrium market. Constraints upon supply increases to match demand increases include shortages in the raw material, natural gas, high cost of investment capital, high equipment costs and long construction delays. The result should be, even under optimistic conditions, considerable shortage and resultant pressure for higher prices through 1979 for ammonium nitrate. The best hope for relief in the intervening years appears to be conservation. In blasting operations, the earliest and best proven route to conservation seems to be improved utilization available from application of highest available technology and most efficient current blasting practice.

Jan 1, 1975