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By Salah A. Taqieddin

The blast casting technique of removing overburden is an innovative technique which was successfully used in the mining of certain surface coal and quarries. This method was found to be efficient in minimizing the labor and equipment cost while accelerating mining operation with safety. This method was successfully applied to horizontal as well as to dipping coal seams. Also it was practically applied to single as well as to multiple ore bodies

Jan 1, 1992

By G Alan Foster

This paper discusses the cause of air blast and modern techniques to reduce this at the source. In addition it raises the problem of their marked variability due to prevailing weather conditions and how weather data can be obtained and used in the control of air blast.

Jan 1, 1975

By G J. Kulbieda

The Empire Mine initiated production in 1963. Since then the unit operations of drilling and blasting have evolved continually in order to meet the increased mining requirements demanded by plant expansions in 1968, 1973 and 1980. Additionally, advance mine planning has become an integral part of proper pit development and is necessary to insure uniform blending of the distinct ore horizons contained within the mine area. Blasting practices have been modified to facilitate the autogenous grinding system utilized at Empire and pioneered in the Iron Ore Industry. Technical innovations in the explosives industry, as well as, progress regarding on site blast engineering methods have substantially increased the use of ammonium nitrate explosives and helped to establish efficient charging procedures. In addition, the recent introduction and use of ammonium nitrate fueled with nitropropane and methanol indicates that it is a viable substitute for aluminized ANFO.

Jan 1, 1981

By Mark S. Stagg, Steven V. Crum, Stephen A. Rholl

As part of its ongoing research concerning rock fragmentation by blasting, the Bureau of Mines has undertaken a series of test blasts where six cylinder-shaped pieces of granite rock were fragmented using high explosives. The tests were intended to: 1) Establish a dataset that could be used in the development and verification of theoretical models that simulate rock blasting and 2) To add to the fragmentation data currently being collected by Bureau researchers. The cylindrical geometry was chosen so that the fragmentation could be directly compared to two-dimensional computer simulations that assume an axisymmetric configuration as well as more sophisticated three-dimensional models. The granite cylinders, Carnelian granite and Charcoal granite, ranged in size from about 0.46 meters (18 inches) to 0.58 meters (23 inches) in diameter by 0.91 meters (36 inches) to 1.52 meters (60 inches) in length. Physical rock properties tests performed on the Charcoal granite cylinders indicated that the rocks did in fact have similar physical characteristics. PETN-based detonating cord and dynamite were used as the explosive charges and estimates of the values of some important physical properties are given. For the first five tests, the blasted rock was contained by a heavy rope mat suspended inside the Twin Cities Research Center's blasting shelter. The fragments from each of these shots were sorted and weighed to determine the corresponding fragment-size distributions. Even though different types of granite and cylinder sizes were used, similar fragment distributions were produced from shots that used a similar explosive, in this case the PETN-based detonating cord, and comparable burden-to-charge diameter ratios. Significantly coarser fragmentation was produced from a blast that used dynamite as the explosive charge. Fragment velocities were calculated using photographic data from the sixth test which was shot unrestrained in a quarry and filmed with high-speed cameras.

Jan 1, 1990

By D G. Dressler, Paul Yeager

A previously little-known facet of seismic frequency spectrum analysis is gaining significance. The frequency spectrum of seismic waves promulgated from blasting is a significant factor in causing blasting complaints and threshold (architectural type) damages.

Jan 1, 1987

By Kamal Wadhwa

Ever since the introduction of Liquid oxygen explosives in India in 1927, these explosives are being extensively used in the various mining industries such as coal, ironore, limestone, bauxite, magnesite etc. The earlier LOX compositions were based on cellulosic material of Weberlox series of French origin. They contained the basic ingredients of saw dust with an admixture of cork dust, some hydrocarbons and some metallic powders. However, there were some inherent defects in the soaking characteristics of these compositions, in as much as, absorption and retention of liquid oxygen in the cartridges were not properly regulated in the fine pores and in the inter-granular spaces inside the ingredients in a uniform manner.

Jan 1, 1989

By Jaki M. Wilson, Neville T. Moxon

The detonation pressure of ANFO can be significantly reduced by the addition of low density materials such as polystyrene, bagasse, sawdust or perlite. Laboratory and field test results have shown that homogeneous mixtures of these low density explosives can be produced in a bowl truck and loaded into a blasthole without segregation. The detonation pressure of the mixture can be altered to be more compatible with the material in which it is being used by varying the quantity of low density additive incorporated into the mixture. Field results have shown that these low density explosives can lead to significant cost savings without compromising fragmentation or production.

Jan 1, 1989

By Dwayne Tannant, Jeffrey Loeb

Blasting techniques and protective measures exist that can mitigate risks associated with flyrock and the nuisance of vibration, and overpressure. However, these are often misused or not used because there are no prescriptive regulatory requirements and typically urban blasting guidelines do not exist. The relationship between the increasingly negative publicity that the urban blasting industry receives and the existing state of regulatory control on blasting in urban environments is presented.

Jan 1, 2012

By H. Frank Murati, D. S. "Sax" Saxena

The presence of a mobile home park with drinking water wells created a unique geoenvironmental deterrent to the developer’s plans for effective rock blasting, excavation, and development of water management areas (lakes) in connection with the construction of Crown Colony Resort, a residential cum golf course community in southwest Fort Myers, Lee County, Florida, USA.

Jan 1, 2002

By Paul Worsey, Gerald Rupert, Mark Kirkbride

The realignment of Highway H in the proximity of Crystal Cave (Springfield MO.) required the development of a blasting program that was both economical and efficient for construction, yet ecologically safe for the cave. Three component seismographs were strategically placed underground near prominent and sensitive cave features and the vibration levels from the construction blasting continuously monitored. Peak particle velocity (PPV) values were found to obey the square root scaling law and a peak particle velocity value of 0.3 in/sec was chosen as the safe maximum limit. This value proved adequate in preserving the integrity of the cave and its features. Scaled distances for the maximum and lower values enabled blasting personnel to select explosive charge weights per delay for given distance to the cave. Delays were determined from the dominant frequencies recorded underground.

Jan 1, 1997

By Clifton W. Livingston

This paper is the first of a series in which evidence suggesting a quantum mechanical behavior of materials in blasting and high energy impact loading is presented. Such evidence relates the mechanical behavior of materials to their electro-magnetic behavior at successive stages in the development of the electric and magnetic fields as the disturbance proceeds outward from the borehole in blasting.

Jan 1, 1981

By Joshua Hoffman, Catherine Johnson, Braden Lusk

The practice of dual initiation using precise timing from electronic detonators in boreholes is thought to be beneficial for increasing fragmentation at a desired location in the rock strata. This increased capacity for fragmentation is understood to be a product of both the collision of detonation waves in the explosive column and an increased energy liberation rate, each resulting from dual initiation. In addition, the collision of shock waves from two adjacent blast holes is suggested to improve fragmentation at the location the two shock waves meet, which can be controlled with precise timing. This paper presents the results from scaled laboratory experiments where converging detonation waves and shock waves were studied.

Jan 1, 2014

By Donald J. Westmaas, Fred C. Drury

The factors affecting the selection and use of exploisves have changed radically in the past three decades. The objective of this paper is to point out considerations which should now be employed by the Explosives Engineer in his selection and use of modern chemical explosives.

Jan 1, 1978

By Lina Lopez, Jose Sanchidrian, Manuel Lopez, Pablo Segarra

Previous work in which rock properties and blasting parameters (geometry, charging and timing) were reported together with truck filling times, is taken as a starting point for a thorough analysis of the influence of the former on the mucking velocity. The experimental set was composed by 11 blasts made in an open pit mine. Non-parametric, distribution-free statistics is applied. The mucking rates (in bank cubic meters per unit of bucket volume and per hour) appear to be clearly dependent on the explosive energy and powder factor, both magnitudes combined as energetic powder factor (energy per unit of rock volume). The mucking rate is a non-monotonic function of such factor in the range of the blasts analyzed. The determination of the function is optimum when the fraction of the explosive below grade is not considered and when the explosive energy is qualified as that delivered at a partial detonation regime. Different types of loaders seem appropriate for different energy levels. At low levels both front loaders and rope shovels obtain small productivities without a statistically significant difference in their performance. At high energy levels, front loaders qualify higher than rope shovels. Mucking velocities can be equally small at low energy powder factors and at high ones if rope shovels are involved.

Jan 1, 2008

By Michael S. Wieland

The stress waves generated during delay blasting in underground or surface mines not only fracture the surrounding coal, rock, or other strata, but also impact delayed charges remaining in neighboring boreholes. This crossing wave interaction is a ubiquitous fundamental damage mechanism, ultimately responsible for numerous occurrences of misfires and flyrock. The hazards and waste from wave-induced malfunctions are Just the recognized tip of the iceberg. Undetected marginal performance of damaged delay detonators and desensitized charges poses a tremendous unresolved problem, resulting in the reduction of mining profits and the certain retention of unwanted risks.

Jan 1, 1988

By Selwyn Pearton

Pumpable emulsion explosives have been available to surface and underground massive mining operations for decades and through their unique properties offer significant advantages through improved safety, reliability and performance. Despite their advantageous properties, the benefits of pumpable emulsions have been unavailable to narrow reef mining operations due to the void in technology necessary for their successful implementation within the challenging environment. Despite efforts to promote and enhance the safety and performance of bulk emulsions for narrow reef stoping, little research has been undertaken to advance the pump technologies required for their implementation. This has resulted in a gap in knowledge and technology and as a consequence the successful implementation of a pumpable emulsion system has consistently eluded the narrow reef environment.

Jan 1, 2015

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 P D. Katsabanis, L Liu

Numerical modelling of fragmentation and throw is used to provide information on practical blast design parameters. The function of airdecking and its practical implications, the importance of the initiation point and aspect ratio of cratering charges and the timing between adjacent blastholes are investigated. Accuracy requirements for detonators are discussed with emphasis placed on the volume and fragmentation of the blasted rock, and compared to experimental results. Practical guidelines which have been based on intuition are examined using the model. Some of the predictions have been tested and correlate well with experimental results, obtained in the laboratory. Findings show that a minimum airdeck length is needed to realize any benefit from the application of airdecking in production blasting while the process can enhance the shock energy provided by non-ideal explosives significantly, bottom initiation of charges is beneficial to fragmentation and the aspect ratio for cratering charges can exceed the traditionally accepted ratio of 6. Regarding timing, in the ease of cratering charges, true simultaneous initiation shows beneficial results for the volume of blasted rock; however the accuracy required for practical detonators is very high. Fragmentation improves after a certain delay time while the optimum can be achieved at a range of delays. Timing affects muckpile shape; however it appears that subtle differences in delay times do not have a significant effect.

Jan 1, 1997

By Donald D. Eilers, Pharis E. Williams, Thomas O. McKnown

The Continuous Reflectometry for Radius vs. Time Experiment (CORRTEX) system was developed by the Los Alamos National Laboratory for determining the energy released in a nuclear explosion by measuring the position of its shock front as a function of time. The CORRTEX system, fielding techniques, and the methods and software for data reduction and analysis were developed over a 15 year period with hundreds of measurements made on nuclear tests and high explosive experiments. CORRTEX is a compact, portable, fast-sampling, microprocessor-controlled system, based on time domain reflectometry, requiring only a 24 volt power source and a sensing element. Only the sensing element (a length of 50 ohm coaxial cable) is expended during the detonation.

Jan 1, 1995

By Greg Mclellan, Mark Johnson, John Pepper

Several large quarrying projects recently occurred in Miramar, Florida. These were closely monitored by the Seismologist of Record and Broward County in accordance with County and City regulations. In addition to this monitoring, the City of Miramar employed The Pepper Engineering Group, Inc., to provide additional spot check monitoring and to review the records of the other two parties on a routine basis. Broward County ordinances require that the location of each shot and the nearest protected structure be recorded along with seismograph measurement of each shot at the nearest protected structure. The positions of the blasts and nearest protected structures were determined using GPS. The blast vibrations were measured by seismograph. Over 600 shots, which are the subject of this study, were measured both by the County, the Seismologist and, on many occasions, The Pepper Engineering Group. As such, the vibration data was constantly cross-checked for consistency. The blasting contractor also provided blast designs for each shot. In this paper, the measured vibrations are plotted in terms of Resultant Peak Particle Velocity (RPPV) versus Scaled Distance (SD) on logarithmic scales. The data curves are fitted with least squares and upper 95% and 99% prediction limits are provided. Equations are presented to predict the RPPV based on scaled distance and prediction level using power fits. Statistical information concerning the derivation of the various limits is presented. The raw data used to develop this paper, along with other information concerning the shots, will be posted on the Internet for use by other researchers.

Jan 1, 2000