Search Documents

By Tapan Goswami

This paper discusses the importance of coal mapping, the rock properties of the roof and floor interface of the coal seam, and the significance of loading and initiating designs in minimising coal damage. Furthermore, the importance of using electronic initiators cannot be emphasised enough. This paper also discusses how a cast blast can be initiated from many locations by mitigating geological abnormalities and thereby avoiding spatial movement of rock shearing in a plane above the coal seam.

Feb 1, 2020

By N. Rouse

Underground raises and slots are a vital part of underground blasting operations. Raises and slots are vertical shafts or openings used for ventilation, ore passes, or creating voids in stopes. In the author’s experience, raise and slot designs can vary significantly from operation to operation or even within a single operation, sometimes for reasons unknown. The results of the various designs can differ depending on drilling accuracy, geology, and the explosives used in the design. The purpose of this paper is to summarize the recommendations found in published literature on raise and slot design in one document, while incorporating some of the author’s own experience with optimizing raise and slot designs in underground operations. Some inspiration is also included from burn round designs; small versions of raises drilled horizontally in development blasting rounds. This document includes discussion points on drillhole diameter and depth, pattern design and relief requirements, explosive types and loading recommendations, and timing. Ultimately, this document can be useful to those looking to design a raise or slot blast for the first time or for those looking to improve on the results from the raise and slot blasts used at their operations.

Jan 1, 2024

By John C. Brulia

The IME member companies, the ISEE along with its chapter organizations, the Federal, state and municipal regulatory agencies, and the industry consultants and suppliers have developed safety equipment, provided safety guidelines, promulgated safety-oriented regulations, and conducted safety training for blasting personnel in an effort to reduce explosives-related accidents.

Jan 1, 1994

By W. L. Saunders, Richard T. Dana

The dynamites are graded according to the percentage of nitroglycerin that they contain. Thus a “40% powder” would be one in which the sticks, weighing one-half pound each, would include one-fifth of a pound of pure nitroglycerin. Dynamite is usually packed in paper cartridges weighing about one-half pound each which will vary in diameter. When ordering, it is customary to specify a size of cartridge that will as nearly as possible fill the drill hole, the commonest size being 1 ¼” in diameter by 8” in length. It is nearly always shipped in 50-lb. boxes, which have a volumetric capacity of 3/4 cu.ft.

Jan 1, 2013

By Emily Johnson, Catherine Johnson, Rachel Bauer, Paul Pitzel

Demolition projects involving explosives may incorporate cutting charges to sever columns in collaboration with kicker charges that “move” the columns out of alignment. Traditional kicker charges often involve the use of dynamite secured to the column above the cutting charge. Nitroglycerine, the main component of dynamite, causes medical problems and can be a hazard to workers on site. Dynamite can also cause fragmentation of the column and structures, resulting in potential injuries to people or leading to the possibility of cutoffs in neighboring charges. This study investigates the use of water-cased kicker charges to reduce the amount of dynamite in demolition. Water charges, traditional charges, and detonating cord charges were placed on hanging steel columns and analyzed for the fragmentation of the column and velocity of the column. A W 10 X 22 beam was hung in an underground limestone test area and allowed to swing freely acting as a severed column. Charges were attached to the bottom of the column with tape and initiated using electric detonators. Explosive charges of dynamite or detonating cord were placed in the center of a water container or directly on the column for use as the kicker charge. Tests were recorded with high-speed video and velocity was calculated using Phantom Camera Control software. Velocity and time were then used to calculate force, kinetic energy, impulse, and pressure exerted by the explosive on the column. The water charge transferred energy to the column over a larger area with no direct contact of explosive and the column. Water charges moved the column faster and with more power than traditional charges. After preliminary tests, water charges were also used as the primary kicker charges in a full-scale demolition project as a case study using 118 charges. The kicker charges successfully moved building members without creating fragmentation while using less dynamite than traditional kicker charges. Due to the success, multiple full-scale projects are being designed using water charges to show success and repeatability.

Feb 6, 2023

By M R. Hettigner, J Nawrocki, C E. Johnson, P G. Cahill

This study evaluates the effects of both short inter-hole and intra-hole delay times on rock fragmentation and throw. Full-scale test blasts were analyzed at a granite quarry in Talbotton, GA. This analysis provides a representative understanding of timing effects on fragmentation in the field, different from previous lab scale studies that negate the effect of geology. Inter-hole delay times between 0 ms and 25 ms were tested on a series of 4 bench blasts and subsequently examined using photographic fragmentation analysis methods.

Jan 1, 2017

By Lon Santis, Michael Swisdak, David Leidel, John Tatom

The Institute of Makers of Explosives (IME) and A-P-T Research, Inc (APT) have developed and released a quantitative risk management tool, IMESAFR (IME Safety Analysis For Risk), for the commercial explosives industry. Consequence algorithms in IMESAFR are considered state-of-the-art. Generally, they mirror those in SAFER (US Department of Defense Explosives Safety Board quantitative risk management software). The science behind the software has now been assessed for its maturity. Results have identified areas where additional test consequence data could improve predictions. To address these areas, full-scale testing programs to provide the needed data have been formulated. Proposed testing efforts include work to: (1) improve characterization of explosive articles now absent from SAFER, and (2) refine modeling of the Potential Explosion Site (PES) types, particularly small metal structures, also not found in SAFER. Goals of each program as well as requirements for conducting the tests have been established. Testing results are to be used to improve the algorithms and to further the state-of-the-art in risk-based explosives safety.

Jan 1, 2012

By Thomas E. Ricketts

Occidental Oil Shale Inc. has spent the last eight years at its Logan Wash. mine near DeBeque, Colorado, developing its modified in-situ oil shale process for obtaining oil from oil shale. Modified in-situ technology involves large underground chambers, or retorts, which are formed by mining out a minimal volume of rock to allow explosive expansion of the surrounding rock into tile mined void volumes. The resulting rubblized retort volume must contain a fairly uniform particle size distribution and void distribution to permit maximum oil recovery during subsequent in-situ processing operations. The more uniform the rubblized volume of particles, the more oil recovery obtained during processing. The processing involves first igniting the top of the retort and then. injecting air into the top of the retort to drive the combustion front downward through the entire rubblized volume. The oil is continuously collected at the bottom of the retort during the processing.

Jan 1, 1981

By Greg Quinn

After a long week of work in Colorado Springs this past July, I was looking forward to flying home to start a long anticipated family vacation. As I grabbed my seat on the plane, a man sitting next to me innocently inquired, to the row as a whole and not to me in particular, “I wonder what the weather will be like in Phoenix”? To most people, this is a common (maybe the most common) topic of casual conversation. To a meteorologist that just dealt with six thunderstorm delays at a major golf event over 4 days, well, lets just say the smirk on my face said it all. After giving my flight mate a detailed forecast and a short explanation on why I would know such information, I sensed, correctly, the inevitable follow up question was coming. “Why would you need a meteorologist at a golf tournament?”

Jan 1, 2012

By Robert B. Hopler

The history of bulk loaded explosives begins with the loading of black powder and RRP (Railroad Powder) into vertical boreholes. The early air place, net of black powder and nitrostarch dynamites is covered, as are the brands and formulas of the nitroglycerinsensitized "Bagged" powders.

Jan 1, 1993

By Leslie Taylor, Uli Leiste

In this paper, results from small scale testing conducted to determine pressure time profi les acting on a plate (taken to represent the bottom of a vehicle) at any given distance from the center of the plate will be presented. These results will be discussed in relation to visual observations of the upward moving sand.

Jan 1, 2008

By Eric Grigoryan, Wade Hutchison

An engineering study of 2,250 blasting damage claims from 1999 to 2008 in Tennessee, Kentucky, Virginia, Nevada, California, Georgia, South Carolina, North Carolina, Alabama, Arizona and Utah were investigated over the last decade and these investigations determine that blasting ground vibrations damage claims are valid less than 1.3 percent of the time. This study determined that valid blasting damage occurred as a result of impact damage associated with fly rock, air concussion stressing, instantaneous reverse stressing associated with ground vibration and crater zone soil shifting related stressing.

Jan 1, 2009

By D Anonby

The Fox Pit at EKATI Diamond Mine is designed with 11 m wide benches excavated using a double benching technique leaving 30 m high faces. Blasting tests were conducted to increase the percentage of benches that meet an 11 m catch width. The subdrill depth for the lower bench trim blasts and the blasthole diameter for the upper bench trim blasts were reduced to maintain the bench crests. Raising the lower trim blastholes by 0.5 m decreases the depth of broken rock below the final bench elevation, and consequently reduces damage to rock that forms the bench crest below. The use of smaller diameter (165 mm vs. 270 mm) blastholes in the A and B rows for the upper trim blast reduces the charge per delay during detonation, reduces the powder factor slightly, and reduces the energy affecting the final pit wall and crest.

Jan 1, 2007

By Michael Wieland

Sharp transient stress waves generated during the delay blasting of underground coal can damage unfired borehole charges remaining in the delay pattern. These tremendous stress pulses in coal bear a strong resemblance to underwater shock waves, despite differences in rise times, damping rates, and scaling relations. "Shock wave" terminology is adopted to distinguish the sharp transient waveforms propagating through the coal from the gas-driven stresses that rift the coal. Reported waveform characteristics of shock waves through underground coal were utilized to design a simulator test for rating the impact resistance of cap-sensitive explosives. Theoretical minimum borehole separations were determined for each cap-sensitive explosive from the requirement that worst-case waves hitting an unfired charge would not exceed its impact resistance rating. Rugged explosives have higher impact resistance and will function properly at smaller borehole separations. Additional work is required to verify the findings from the simulator technique and modeling relations reported here.

Jan 1, 1990

By Ron J. Elliott, Corry Coumans

The following is a detailed description of the blasting procedures used in the successful demolition of the Stave River bridge, Mission, British Columbia, Canada. This highway bridge spans a highly sensitive salmon-spawning river. Demolition of the bridge took place in a high liability situation in close proximity to sensitive structures. The new highway bridge carrying an exposed 150mm diameter gas line was located only 1.5 meters away. The bridge piers were blasted only seven meters from overhead power lines. Control of blast vibration, flyrock, and underwater overpressure was critical to the success of the operation. Electrical sequential blasting was used to ensure that blast vibration on the new bridge structure was kept below 50mm per second.

Jan 1, 1998

This paper is written in response to a request from the UTRC Committee on Perimeter Control Blasting. That Committee is conducting "follow-on" research on the selection of appropriate blasting designs and products for perimeter control of rock excavations. This paper will deal with the rock mechanics principles which affect the outcome of such blasting, and explain to the reader how to apply techniques which will modify the typical site response one would expect for conventional blasting methods. For convenience of reference, and to emphasize the important concept that the application of this technique is site specific, that is it must be custom-designed for each site, the technique is being called "Modified Site Response Blasting".

Jan 1, 1984

By Ankit Jha, Sudarshan Rajagopal, Purushotham Tukkaraja

Geologic structures are one of the crucial parameters in blast design. Structural geology and rock properties influence drilling patterns, blast layout, and initiation systems. A comprehensive understanding of structural characteristics is essential to achieve the desired blasting objectives. This paper aims to identify geologic features in a bench using images obtained from the drone. Images obtained from mine site are annotated for geological features such as faults and joints. Semantic segmentation of images is achieved using an encoder and decoder structure available in the machine-learning pipeline. The encoder consists of initial convolution and pooling layers to capture essential features of the geology and rock patterns from two-dimensional RGB images. Batch normalization is used to put all the features on the same scale. These images are then inputted as training data for the machine-learning algorithm. Machine learning model is trained on sub-section of interest to achieve reasonable accuracy. Initially, 1000 best annotations were used to train the model and additional samples were added later to achieve more accuracy and avoid iteration of machine learning model in wrong convergence. After the model achieves reasonable accuracy, it is used to recognize geological features on new data. Geological features identified on the new data can be used by the blasting crew in blast design and keeps the geological maps updated that can help the geotechnical team.

By Anders Nordqvist

LKAB operates an underground iron ore mine in Malmberget in the northern part of Sweden. Twelve different orebodies are mined today using both longitudinal and transversal sublevel caving as mining method. The town of Malmberget is located close to the mining area. The need for urban transformation, moving people and houses, is evident for many reasons. The mining methods used have inherent subsidence issues and there are also vibrations from blasting and mine induced seismic events.

Jan 1, 2018

By Bob de Raadt

For a long time industrial underwater blasting has stood in need of a calculation method, for the determination of shockwave-proof as well as shockwave-effective charge distances to objects in water. After a brief discussion of the physical background of the shockwave mechanism in water, the author discusses an empirical theoretical computing method based on the "Bubble boundary" concept. The practical application of this model is finally shown in an account of a few underwater blasting operations in which charge weights of c.1-1000 kg were involved.

Jan 1, 1980

By J. Meissner

In this paper vibratory crack response is compared to that produced by volumetric changes in foundation soils induced by natural events. These natural phenomena include changes in the water table, changes in soil moisture, and formation of ice lenses to name a few. Previous papers have compared vibratory responses of cracks to atmospheric effects such as those produced by the passage of weather fronts and daily changes in temperature and humidity. Periodicity of these atmospheric effects is on the order of a day to half a dozen days. Thus it is possible to observe atmospheric effects with measurement over a period of weeks to several months. On the other hand, crack response produced by volumetric changes in foundation soils occurs over a period of many months and/or may be seasonal in nature if not longer in the case of drought. Thus its measurement requires long periods of observation (many months to significant fractions of a year) or observation during critical seasons. Since it occurs over long periods of time, its observation may be obscured by climatologically induced crack response. These soil volume changes are compared with climatic data to describe the correlative nature of crack response in time with the soil volume change phenomena and likely climatic causes.

Jan 1, 2009