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By Douglas Bartley, Jay Elkin

The state of Pennsylvania was at one time one of the leading coal producing states in the east. However, legislation and industry trends over the last 10 years have adversely affected the amount of bituminous coal mined in Pennsylvania and the whole eastern United States. The application for and approval of a new mining permit is a very costly and arduous task. When a new mining operation is established it is crucial that nothing within the operator’s control causes the operation to stop producing. This paper discusses the action taken by a small mine in Pennsylvania when their blast induced vibrations rose to levels that typically would have resulted in a total mine shut down by the regulatory body governing such operations.

Jan 1, 2003

By Neal Lee, Braden T. Lusk, Jhon Silva-Castro, Patrick J. Jenks

"Timing and charge sequence are very important for optimized blast design. Traditional nonelectricinitiation systems have moved the industry toward a system of delays consisting of hole-to-hole androw-to-row timing sequences that mimic the application of nonelectric surface delays or dual delayinitiator systems that have been prevalent in the blasting industry for many years. The increasedutilization of electronic detonators allows for the use of Regular Rhythmic Timing (RRT) utilizing onlyone delay between charges and a selected charge firing sequence. The hole to hole and row to row (HHRR) timing method has been utilized for blasting optimization and allows for simplistic changes to the tie in phase of the blasting sequence. When using this traditional timing methodology, for some specific cases related to the number holes and rows, crowding occurs in the delay between charges with subsequent increase in the peak particle velocity (PPV) produced by the blast. This is in contrast to RRT where the timing between the delays remains constant."

Jan 1, 2016

By W. J. Birch, D. Leckenby, R. Farnfield

The use of electronic detonators to improve fragmentation is becoming universally accepted. However their use in limiting peak particle vibrations levels is still in its infancy. Most of which is anecdotal, in that few actual scientific studies have been carried and published. This paper details the research work carried out at a limestone quarry in the County of North Yorkshire in Northern England. Here a series of blasts were carried out some used non-electric detonators whilst others used electronic detonators. The majority of blasts were carried out at the same burden, spacing and deck charge weight loadings. Initially, the key variable was the difference in detonator type and then leading on to using the electronic detonators at specific exact different detonator timing intervals. Later the study was extended to include double row as well as single row blasts.

Jan 1, 2007

By Michael S. Wieland

Toxic fumes cause fatal and nonfatal incidents in underground mining, where the working environment tends to trap the fumes, hindering the restoration of nonharmful conditions. Workers can underestimate the residual fume toxicity and return to the work site too quickly. The toxic fumes from charge explosions depend upon a number things: formulation ingredients, mixture uniformity, water resistance, hole contaminates, rock hardness, and dust interactions. Hole-to-hole shock waves and rift compressions can partially desensitize charges, ruin the reaction kinetics, and worsen the fume toxicity. Traditionally the fume hazards for candidate explosives are resolved for a restricted set or tally of theoretical or measured fume components, transformed to standard reference conditions. The relative fume toxicity RFT is the resultant influence reckoned from a formulated sum of concentrations within the tally that are unweighted or weighted with chosen multiplying constants. The RFT result is compared to a rule criterion that represents the worst case tolerable fume toxicity stipulated by regulations or otherwise. The ranking and comparison of different hazard potentials that would otherwise remain unwieldy is rendered tractable by the common format of the RFT notation.

Jan 1, 1998

By William Reisz

Over the years as surface mining operations have become more sophisticated, angle drilling has become a more popular blast design technique, especially in areas where overburden and stripping ratios have increased. Another method of blast design is the staggered pattern, which greatly improves explosives distribution within the blast. While both methods present some engineering challenges, this paper will discuss how the two methods can be combined to enhance fragmentation, improve cast percentage, drill production ratios and highwall control. A practical engineering approach will be presented as well as a discussion on the discipline required to maintain a quality blasting plan.

Jan 1, 2002

By Douglas Bartley, Brian Wingfield, Robert McClure

Recent studies and limited tests indicate favorable results utilizing high accuracy electronic detonator technology over conventional non-electric pyrotechnic systems. This study discusses the application of this technology using the Daveytronic programmable system in an on-going production basis. The study quantifies the performance as it relates to fragmentation, excavation, vibration and productivity in an eastern U.S. aggregate mining operation.

Jan 1, 2001

By Steven Putt

Seismic While Drilling (SWD) is a newly developed technology in the mining industry. Improving upon Measurement While Drilling (MWD) systems, SWD measures mechanical properties of the rock at incremental depths down a blast hole at a much higher resolution. SWD is also immune to common failures and inconsistencies of MWD such as operator and drill specific variation. Seismic While Drilling records the velocity and elastic modulus of the rock with centimeter accuracy in real-time. These properties measured while drilling blastholes are then used as a proxy for density which can be used for: • High resolution geologic modeling • 3D ore control • Drill and blast optimization • Drill to mill tracking One of the distinct challenges with SWD systems is the sheer volume of information acquired. With thousands of measurements per blasthole, the data can be overwhelming for even an experienced engineer. To overcome this complex challenge, the latest cloud computing and analytics models have been simplifying and organizing the data. These newer technologies can amplify an engineer’s capability by delivering actionable insights into their drilling and blasting workflows. The paper presents new results from Datacloud during recent Seismic While Drilling trials in iron ore, metallurgical coal, and hard rock mines around the world. The measurements are compared with wireline geophysical logs, core data, drill cuttings, and conventional measurement while drilling (MWD) systems to validate the technology and show how the data can be used.

By Paul Worsey, Larry Frost, Braden Lusk, Seok Bin Lim

For certification of blast resistant windows, current tests consist of arena tests or large air gun tests. Arena tests involve the detonation of more than 1000 pounds of explosives with windows placed in the range of hundreds of feet. The result of an arena test is a loading on a window consistent with an expected industrial or terrorist blast. Due to the nature of this type of test, only a limited number of facilities are available and operational costs can be extremely high. Air gun tests involve the use of compressed air and a failing diaphragm fired through a large tube. Although this test is more cost effective and easier to administer with lower environmental impacts, it is not an explosive loading and does not create a negative phase on the tail of the pressure pulse. Simply using a small charge in close proximity to the window is not a viable option either. The pressure peak can be reached using this method, but the duration of the pressure pulse is such that the positive phase impulse is on the order of ten times less than that for an arena test.

Jan 1, 2006

By Takuya Taguchi, Toshihiro Ogata, Atsuio Inoue, Shigeyuki Sasaki

Highly improved drilling machines and mucking machines have been used for the underground construction. To have rapid construction, the roles of blasting operation ha ve been growing more important. At the most tunneling of present, cartridged emulsion explosives have been used for a blasting in Japan. Under this circumstance, a blasting system of ANFO explosives using loading machine has been used recently for a tunnel blasting. However, ANFO has some problems, such as a useless explosives in wet boreholes, bad blasting fumes and the ammonia gas due to the decomposition of ammonium nitrate in contact with the sprayed concrete in tunnel.

Jan 1, 2005

By Charlie Brumbaugh

Antarctica with its diverse conditions such as severe cold, high winds, rock and ice structure and limited explosives available posed many obstacles. This paper will give an overall view of the methods used to overcome these obstacles on a daily basis on the highest, driest, coldest continent on earth.

Jan 1, 2000

By Randall M. Wheeler

The measurement and analysis of blast-induced ground vibrations are more complex than ever before. This is primarily due to the advancements made in microchip technology, mass storage utilities and the computer, which have allowed us to reduce and analyze data in a matter of moments instead of days. Terminologies such as Fourier transform, response spectra, cross-correlation, convolution, deconvolution and half-length frequency, etc. mean little to anyone except those who are experts in the field. A little understanding of the basic concepts behind vibration effects can help a beleaguered end-user feel more confident about what their measurements really mean.

Jan 1, 1992

By Robert Hivick, Frank Sames

The control of environmental effects, especially blast vibration and airblast, has become a dominating planning criterion for most surface blasting operations. Compliance with existing regulations is generally achieved through constraints in the blast design, or monitoring programs. Commonly, blast vibration and airblast signals are rated and compared by their maximum amplitude and the associated principal frequency. However, this data reduction limits the interpretation of the influence of varying blast design parameters on the vibration and airblast.

Jan 1, 1999

By Yasunori Kosaka, Junya Tokita, Aramaki Shosaku, Inoue Junji

Light ANFO that satisfies blasters and customers who want to reduce the amount of explosive consumption without changing blasting effects and designs and passes Cap sensitivity test regulated by law. The reduced loading density of light ANFO reduces the amount of explosive consumption. The loading density of conventional ANFO is 0.X-0.9g/ml, while the loading density of light ANFO is 0.7-OXgiml. The detonation velocity of light ANFO is maintained not to reduce blasting effects. Detonation velocity of conventional and light ANFO using steel tube of inside diameter 36 mm are 3200 - 37OOms. detonation velocities are the same though the loading density of light ANFO is reduced by O.lg/ml. This suggests that the reactivity of light ANFO improves.

Jan 1, 2002

By David Siskind

The authors studied small seismic exploration blasts for vibration characteristics and effects on structures in Mexico. Obtained were 267 three-component recordings of ground vibrations and structure responses from 62 test blasts at six single-story masonry structures. Charges were 4.55 kg (10 lb) of Vibrogel expolsive at depths of 20 and 30 meters. Initial blasts were 240 meters distant and proceeded towards the structures to as close as 5 meters. All blasts were in soil media in two basic types of terrain, low saturated areas and upland dry areas. Structural inspections were before, during, and after the test blasts.

Jan 1, 2002

By Jackson R. Pressley, Bruce Vandenberg

The knowledge of how and when your explosives go off can help you make intelligent decisions regarding future application of explosives thus removing some of the black magic associated with blasting. The net result will be intelligently set-up shots with timing, explosive charges, and placement more accurately done. Lower operational costs can be achieved when the correct combinations are applied.

Jan 1, 1992

In all the industries that require blasting operations using explosives, there exists numerous unwanted side effects of the blast which may pose as environmental hazards. These hazards face prominence, especially in India, where there are very stringent rules and regulations governing the use of explosives. The environmental hazards associated with blasting operations as a whole can be tacked successfully to a certain extent depending upon the ultimate expectations of ,the post-blast effects and the limitations of the environmental obligations as specified by the authorities from time to time and from place to place. The main parameters which require attention to limit the post-blast results to the optimum level are ground vibrations, dust pollution, gas pollution, air blast effects, noise pollution & fly rocks etc.

Jan 1, 1995

By Chris Breeds, Larry Leone, Jerry Wallace

Project Owners typically require General and Detailed Blast Plans when blasting close to important structures and specify the maximum allowable peak particle velocity for each potentially affected structure. Low, residential level PPV limits may be specified which significantly restricts the potential for blasting to be effectively used. Contractor’s responding to these contract conditions typically cite historic case studies which may, or may not, apply to the specific situation and/or types of structures for which limits have been set. A long submittal cycle typically follows.

Jan 1, 2010

By Jay Rodgers

There has been a longstanding acceptance that burden plays a major role in the magnitude of ground vibration amplitudes generated from surface blasting. Much of the data that this belief is based upon is empirical in nature and may or may not represent an example of false inference. Recent published reports have rightly questioned the influence of burden and confinement on blast vibration amplitude, suggesting that the fracture condition of the rock mass is a better indicator. The increased investment in electronic detonators as a tool to control ground vibration amplitudes demands an understanding of vibration production detailed enough to make use of the vastly improved timing accuracy that they provide. A more accurate relationship may be found if we strip away the assumptions of the past and search for the underlying mechanism of vibration production in surface blasting. We must answer the question: What happens at or near the borehole when an explosive charge detonates that produces ground vibrations?

Jan 1, 2003

By Darren Thorton, David Sprott, Ian Brunton

Blasting causes movement of the rock and can be detrimental to the accurate delineation of the ore and waste regions within the resulting muck pile. The consequences can be ore loss and dilution. However, ore loss and dilution can be minimized and significant increases in profit can be realized if the movement can be accurately measured. Various methods have been used to measure muck pile movement including poly-pipe, chain and sandbags but these have been either inaccurate or impractical. The Julius Kruttschnitt Mineral Research Centre, JKMRC, has developed an electronic blast movement monitor that provides accurate three-dimensional movement vectors following a production blast. From this information, the ore block boundaries in the blasted bench can be adjusted to compensate for the measured movement and then ore recovery can be optimised. Following initial development of the prototype technology, the JKMRC further developed and demonstrated the system in actual production blasts at an open pit gold mine operated by Placer Dome Inc.

Jan 1, 2005

By Bruce Vandenberg, R. Frank Chiappetta, John Foley

Recent advances in solid-state, field portable, fast framing compact video camera systems and PC based frame capture hardware now allow blast imaging up to 1000 frames per second. Up to 4.1 seconds of data can be captured directly into the unit, downloaded to a PC or archived to a standard VCR without data compression. Since no film processing is involved, motion analysis can be performed instantly and on-site within a few minutes. This paper will describe the design features and applications of the MotionMeter system and compare these with the analogous aspects of film-based cameras and other systems. Of all blast monitoring systems and techniques available today, high-speed motion picture photography and videography still remain as the most valuable, stand alone, diagnostic techniques for troubleshooting and evaluating full scale blasts in the mining and explosives industries. High-speed image data, coupled with information obtained from other instrumentation systems, such as continuous velocity of detonation recorders, laser surveying systems, refraction and ground vibration recording seismographs, etc., can eliminate many assumptions about what actually took place in a blast. Thus, diagnostic confidence in evaluating both excellent and poorly designed blasts is increased, and optimum blast results, (which are application dependent), are achieved considerably faster when compared to the trial and error approach of relying on strictly the experience factor. Applications include developing site-specific blast designs, decay equations relating burden, burden velocity and explosive energy, determining ground response times, reducing coal damage, quantifying backbreak, evaluating the effectiveness of sternming, checking delay detonator firing times, evaluating air decks and for studying general dynamics. Motion analysis is performed with a 2D and 3D software package developed specifically for video analysis, but is also directly applicable to film analysis when using a digitizer. Dimensional controls, lens aberration, field set-ups and camera orientation are all automatically corrected for with matrix analysis.

Jan 1, 2000