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By Robert Martin, Brian W. Stump

As part of a series of seismic experiments designed to improve the understanding of the impact of mining blasts on verifying a Comprehensive Test Ban Treaty, a sixteen station network of three-component seismic sensors were deployed around a large cast shot in the Black Thunder Mine. The seismic stations were placed, where possible, at a range of 2.5 kilometers with a constant inter-station spacing of 22.5 degrees. All of the data were recorded with the seismometers oriented such that the radial component pointed to the middle point of the approximately 2 kilometer long shot. High quality data were recorded at each station. Data were scaled to a range of 2.5 kilometers and the sum of the absolute value of the vertical, radial, and transverse channels computed. These observations were used to construct radiation patterns of the seismic energy propagating from the cast shot. It is obvious that cast shots do not radiate seismic energy isotropically. Most of the vertical motion occurs behind the highwall while radial and transverse components of motion are enhanced in directions parallel to the highwall.

Jan 1, 1997

By Lyall Workman, Jack Eloranta

Blasting has an important impact on mining and milling well beyond the necessary ability to dig and load the ore efficiently. There is an increasing body of blasting research indicating significant impacts in crushing and grinding. These include increased production through higher output and fewer delays for bridging and jamming by oversize. In addition, fragmentation better suited to the crushing and grinding system is indicated to lead to reduce energy consumption by these activities, an important result in today’s environment. An important component of optimum fragmentation for this purpose appears to be micro-fracturing within individual fragments. This differs from fragmentation criteria for loading which focus mostly on fragment size. Therefore, one must analyze blasting broadly to obtain satisfactory results throughout the operation.

Jan 1, 2003

By Alfred Osborne

Progressive cavity type pumps are widely used by commercial explosive manufacturers for pumping water gel, emulsion and emulsion / ANFO blend explosives. Tests by explosives companies and investigations into incidents have shown that this type of pump can develop dangerously high temperatures when operated deadheaded or dry. [i.e. with no flow of product through the pump.] In some tests and incidents, explosion or detonation of the explosive (or residual explosive) in the pump has resulted.

Jan 1, 2002

By Jeff Gore, Jack Dermody, David Gribble, Brett Macaulay, Bart Sharpe, Paul Klaric, Paul Thornley, Ben DeVries

Optimal Fragmentation in Block Caving is difficult to achieve as it is generally defined by the rock mass itself and the way in which the cave is initiated. The lower portion of the cave has even less chance as the material has little time for self comminution. Blast Preconditioning of the Block Cave is designed to engineer the lower section of the rock mass to produce material of a suitable size to assist in the initial cave propagation and improve initial drawbell productivity. At Cadia East a plan was developed to drill 150-metre long, vertical up-holes from the undercut level and blast them fully confined to produce fractures in the rock mass. The blast itself was a simple undertaking. However, in the year preceding the first production blast, all aspects of the process were designed, tested and refined across multiple trials. As this type of challenging application had not previously been encountered in Australia there were many unique situations to address. Products and systems had to be developed and adapted to overcome these challenges. These included: Formulating and manufacturing an explosive that is robust and of a high VoD; designing and manufacturing easy to use electronic initiation systems; and, designing pumping systems to combat high head pressures to allow for successful and safe loading of the holes. Close collaboration with the customer ensured that the trials culminated in successfully blasting a hole containing almost 3.3t of explosive. These trials have since led to the blasting of four holes instantaneously, which contain almost 13t of explosive. This paper describes the various components of the system, the challenges and the final result.

Jan 1, 2013

By Douglas A. Bartley, Davey Bickford, Raphael Trousselle

The long awaited arrival of a high accuracy detonator to reach the explosives end user will provide new opportunities the blasting community to become better equipped and able to improve upon the current approaches and methodologies used in blast design as they apply to the mitigation of adverse effects from blasting. This paper will detail the approach and findings throughout a several month research project to quantify the high accuracy detonator benefits and to mitigate a long standing vibration problem at a hard rock stone quarry in the state of New York. The tests conducted in this study were designed to provide important information as to the relationship between the use of high accuracy detonators and overall blast performance in terms of ground vibration prediction, control and improved rock fragmentation.

Jan 1, 1998

By N. Skopak, C. Aimone-Martin, J. Redyke, B. O. Meins

PipeBlast is a spreadsheet-based calculator based on research conducted by Southwest Research Institute (SwRI), used by the pipeline industry to determine if proposed blasting planned near existing pipelines can be safely executed. The two factors determining “safe” are blast-induced pipe wall hoop stresses and predicted peak particle velocity (PPV) at the pipeline. Although methodology used to predict hoop stresses is somewhat sound, predicted PPV amplitudes are highly exaggerated based on inappropriate attenuation models developed using spherical explosive charges of limited charge weights, placed in soil adjacent to model pipelines that do not represent rock blasting. Hence, pipeline companies readily reject well-design blasts and limit scaled distances far beyond what is reasonable and cost-effective to pipeline owners. Full-scale trench blasting in rock was conducted near a 24in (711mm) diameter operating API 5L X70 grade steel pipeline in Texas to compare PipeBlast model predictions with a Ground Strain Model (GSM) based on field measurements of ground motions on the surface and at the pipeline springline. Results of the GSM were compared with pipeline strains measured using wire gauges mounted on the Springline. The comparative results showed that a site-specific velocity propagation model provided good estimates of ground strains that are replicated on the pipeline walls in terms of hoop and longitudinal strains. Trench blasting 28ft (8.5m) from the pipeline produced ground motions of 7.6in/s (193mm/s). At this ground motion amplitude, the factor of safety defined as the allowable stress divided by the combined operating and blasting hoop stresses was reduce from 3.04 in the absence of blasting to 2.98. This paper explains the research and findings on which PipeBlast is based and presents an alternative approach to predicting blast-induced pipe wall stresses based on site-specific velocity propagation measurements and a ground strain model.

Jan 1, 2024

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 Zvonimir Ester

The course of motorway tunnel under construction was set only 2 m away from the main motorway. The thickness of the tunnel overburden rock was 9 m. During the tunnel construction the traffic on the motorway was not supposed to be interrupted. The tunneling was carried out by NATM with classical drilling of blastholes and by blasting.

Jan 1, 1998

By Michael Wieland

The thermodynamics work-principle was used to develop the rupture-fracture-throw (RFT) model for ranking the performance of reduced-density explosives when shot in rock or other stratum. The RFT model revises techniques used for the rock-water-jelly (RWJ) model, where the reaction-zone remains trapped within the rock/stratum. Therein, ranking of performance refers to trends for the two resolved components of the total expansion work: the reversible mechanical work taken as the heave and the residual irreversible portion, taken as the undissipated shock. For numeric tractability, the RFT and RWJ thermodynamic efficiency were taken equal, while the RWJ late-stage confinement was replaced with restrained venting through the rock, to render the RFT inefficient heave. The transfer of heat from the reaction-zone was neglected and the root-power formula was used to render the gas-covolume. Ranking trends were found for a generic charge formulation over a wide ranging density, with underwater results noted for comparison. Realistic compositions, some with natural resource materials, were treated for just typical and reduced density. Rock characteristics, ranging from hard rock to weak stratum, were represented by their density and rupture compression strength. Quantitative test results for shock or heave in rock remain difficult, so qualitative guidelines remain helpful when reviewing the graphic trends. Theoretical refinements for rock fragment size-distribution remain under development, though some relationships are touched upon to gain insight.

Jan 1, 2011

By Robert Pumpelly

During my nearly 30 years with ATF, (Bureau of Alcohol, Tobacco, Firearms & Explosives), I conducted hundreds of inspections. In many cases hours of time were wasted because the licensee or permittee, who had basically done everything right, was not prepared for the audit. In these cases, required documents were scattered, personnel were unprepared and no plan was in place. This paper will provide some simple steps to avoid these embarrassing delays. A list of common violations is also provided.

Jan 1, 2010

By Ethan Steward, Kyle Perry

To test the effects of impact on mine seals, a projectile generator and two seals have been constructed. The projectile generator is a 12-inch (30.5 cm) inner diameter steel pipe with a 4-inch (10 cm) wall, is 8.5 feet (2.6 m) in length, and sealed on one end. Projectiles are propelled by a charge of black powder with a wooden wad and are held in place by foam sabots in the bore. This system, combined with the large bore, allows firing of many different potential projectiles that may be found in an underground mine at a high velocity into the seals.

Feb 1, 2020

By Deepesh Yadav, B. S. Choudhary

Underwater drilling and blasting is conducted for deepening of sea channels for port berths, lake or reservoirs for water supply etc. so that rock dredging becomes easier. During this process there are several associated unwanted effects having potential to cause damage to surrounding structures and the environment, flora and fauna. Though all these ill effects can’t be completely eliminated but adopting controlled blasting techniques can minimize these to tolerable levels. It is recognized that ground vibrations resulting from rock blasting below water near dam may endanger the safety of earthen dams. Therefore, controlled blasting technique was used to ensure the safety of dam and its efficacy was established by monitoring of blast vibrations. The usage of small quantity of explosives confined in blast holes, non-electrical delay detonators and initiating each hole with a separate delay helped to minimize the ground vibration effects on surrounding structures.

Jan 1, 2018

By Mark D. Kirkbride

This paper outlines the process for designing a hard rock blast in an underground coal mine. The coal mine is located in Western Kentucky and operates four continuous miner units at 7 unit-shifts per day. The mine operates in the Western Kentucky No. 11 Seam with local variations from 4.5 - 5.5 feet seam thickness. The seam has sporadic siderite deposits. Usually these deposits do not significantly interfere with the mining process. When previous siderite deposits were encountered they were small enough to drop an entry for a couple of crosscuts. The blasting plan was called for after a siderite deposit was encountered in the belt entry at about one third of the panel length. The other sides of the panel had been previously mined and sealed so the decision was made to mine through the siderite deposit with the continuous miner instead of abandoning the panel. The deposit was approximately 300 feet in length down the belt entry. Mining through the deposit with the continuous miner was expensive in both terms of production and of wear and tear on the continuous miner. A blasting plan for the siderite deposits was designed to minimize damage to the continuous miner should a similar situation occur.

Jan 1, 1999

By Douglas R. Burns

Complying with SARA-Title III and the Emergency Planning and Community Right-To-Know Act as a Non-Manufacturing Facility. As of August 23, 1988 non-manufacturing facilities storing end using chemicals which require MSDS (Materia1 Safety Data Sheets) must fi1e with SERC (State Emergency Response Commission), the LEPC (Loca1 Emergency Planning Commission), and the loca1 Fire Department a list or copies of all MSDS sheets with the Tier I and Tier II forms completed.

Jan 1, 1989

By Jeffrey N. Deisher, H Y. Fang, Richard P. Scheller, Robert M. Koerner

The need to adequately quantify cracking in structures in the vicinity of blasting activity becomes more important each year. This urgency comes about through a growing number of complaints and lawsuits between the various parties involved, i.e., operator/owner, government, and complaintant. It is felt that existing rules and regulations (mainly based on peak particle velocity of the soil or rock adjacent to the structure in question) fall short of such quantification and lead to confusion in adequately assessing structural damage.

Jan 1, 1977

By Lee Wehner, Daryl Kin, John Bolger

The Maumee Quarry, located in the city of Maumee, Ohio, has large in-situ cavities, ranging in size from 3 ft (.91 m) in diameter to over 15 ft (4.5 m). The drill/blast team challenge is to drill, load and shoot the geologically disturbed rock in a safe, cost efficient manner, while in close proximity to a commercial area. A continuous improvement process, managed by a Blast Optimization Team (BOT), was implemented to quantify the innovative explosive loading techniques that have been implemented. Borehole camera monitoring, modified loading practices, the need for accurate drill hole logging and open communications between the drill and blast crew proves critical to the success of the operation. Safe Standard Operating Procedures (SSOPs) have been developed and are strictly enforced for the drill/blast cycle. All blasts are monitored with seismographs and recorded on video to provide detailed information as part of the Blast Management Plan. Despite the geological challenges, the measurement of rock fragmentation index versus loader dig rates has provided near optimal crusher throughput.

Jan 1, 2007

By Brian Stump, Rong-Mao Zhou

A series of single-fired (simultaneously detonated) explosions were conducted in an Arizona copper mine. The explosions spanned yields from 1700 to 13600 lbs (773 to 6169 kg) and were all detonated in an approximate 100 m by 100 m area. In order to quantify the effect of the mine free-face, the individual explosions were also detonated under three different emplacement conditions including at the free-face of the mine under normal burden, twice normal burden and fully contained. The purposes of these experiments were to investigate: (1) Generation of in-mine and regional phases such as Pg, Pn, and Lg from mining explosions; (2) Quantification of the relationship between yield and seismic amplitudes; (3) Quantification of the effect of confinement; and (4) Similarities and differences between single-fired waveforms and those from delay-fired explosions. Instrumentation was deployed at near-source (100-700 m) and in mine (1-5km) distances. Empirical scaling relations for the different shots in this test series were developed in order to quantify the effects of yield and confinement.

Jan 1, 2006

By Timothy Stark

Blasters are usually strictly liable for injury or damage caused by flyrock (trespassory invasion) and blast-induced vibrations (non-trespassory invasion). The application of strict liability to non-trespassory invasions has resulted in significant litigation that has hampered the use of blasting and the blasting industry. Stark (2002) proposes that blasters should not be held strictly liable for non-trespassory invasions but should be liable only if their conduct is proven to be negligent. This change in legal standard was proposed because improvements in blasting technology over the last thirty years allow blasting to be conducted without substantial risk of harm to property and thus the amount of harm imposed by a blast can be related to the level of care exercised by the blaster. It is anticipated that a negligence standard will reduce the amount of litigation because a plaintiff will have a greater burden to overcome. To facilitate the acceptance of a negligence standard by a court of law, this paper summarizes the standard of care using the 1977 Surface Mining Control and Reclamation Act, extensive U.S. Bureau of Mines research, and current blasting techniques, such as blasting mats. It is important for the blasting industry to promulgate a standard of care so a judge can feel confident that blasting can be routinely and systematically controlled and if the legal standard is changed from strict liability to negligence a subsequent judge or jury will be able to evaluate the level of care exercised by the blaster. This paper also suggests that the industry and/or ISEE develop and disseminate a comprehensive standard of care that courts can use to further justify a change from strict liability to negligence and evaluate the standard of care.

Jan 1, 2003

By Advanced Initiation Systems Inc

10 years in R&D Last 5 years available commercially Worldwide Met strict approvals for manufacturing and use

Jan 1, 2004

By Stephen Mansfield

In open-pit mining operations, the drill and blast processes have a significant impact on the downstream operational performance of crushing and grinding of ores and recovery of metal. The blast pattern parameters, combined with the material properties, defines the run of mine fragmentation, which in turn drives the subsequent energy requirements for further processing and mill throughput. A common parameter used to describe a single hole or collection of holes is powder factor, the ratio of explosives to the quantity of material blasted. One often-neglected aspect of calculating powder factor is the explosives contained within the length of hole drilled into the top of the bench from the previous bench, known as subdrill. Explosives in the subdrill directly affect the bench below and thus do not contribute significantly to the results of the upper bench, even though they are traditionally included in the powder factor calculation. This paper presents geospatial data modelling methods that link individual holes from an upper bench to the bench below. This enables a new method for the calculation of powder factor, whereby the explosives in the subdrill from the bench above are included in the powder factor calculation of the bench below. This method allows for a clearer understanding of the impact of subdrill on fragmentation, and how variations in blast designs in the upper bench, i.e. hole diameter, burden, spacing, subdrill length, explosive type, primer position, etc., and accuracy of implementation, i.e. actual hole depths and explosive mass per hole, affect the powder factor and blasting results in lower benches.

Feb 6, 2023