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By Tacio Ferreira

How state-of-the-art software, data analysis and communication applied to drilling and blasting techniques have have allowed quarries in the Midwest of the United States to improve results downstream

Feb 1, 2020

By David Scutt, David Noon

Blast crews are exposed to a number of major hazards including explosives and chemicals, ground conditions, machinery, unique work environments and specific blasting hazards such as fly rock and misfires. Unfortunately, injuries caused by sudden and/or unexpected movement of ground are continuing to occur. Blast crews are not equipped with the knowledge or tools to understand whether a high wall that they are planning to work under is safe.

Jan 1, 2011

By Jon Hurt, Brent Meins, David Vardiman

"Two test blasts were conducted at the Sanford Underground Research Facility to establish optimum blast designs and to limit blast effects on existing research rooms and equipment in preparation for the largest deep underground excavation in North America. Located on the 4850 Level (4,850 ft below the surface)at the former Homestake Mine in Lead, SD, this excavation is part of the U.S. Department of Energy’sLong-Baseline Neutrino Facility that will house particle detectors for the international Deep Underground Neutrino Experiment hosted by Fermilab. A large array of seismographs was deployedthroughout the 4850 Level to measure ground vibrations and airblast pressures in tunnel drifts and in lab spaces."

Jan 1, 2017

By D. Lee Petersen, Travis Davidsavor

The 2003-2004 expansion of a Duluth medical center required rock blasting adjacent to the existing structures, a Mn/DOT retaining wall and other urban structures. This case history describes the methods of a blast damage assessment, based on blast parameters, excavation locations, and critical vibration receptors (including surgical suites, a linear accelerator and a major retaining wall). The assessment concluded that blast vibrations could be controlled, by limiting charge weight, to eliminate impact at the critical receptors. Prior to construction, we conducted preconstruction surveys on structures susceptible to vibration damage. During construction, we reviewed submittals, observed test blasts, reviewed blasting logs and monitored blasting vibrations. Up to 13 seismographs were used simultaneously. Close coordination with medical center operations personnel was necessary to prevent impacts to critical medical procedures. Measured vibrations were clustered around the predicted values, and attenuated at the predicted rate. High-frequency blast induced ground vibrations induced low-frequency vibration of an adjacent MnDOT retaining wall. Medical center structures were observed to significantly attenuate the ground-borne vibrations. This paper was first published in the Proceedings of the 56th Annual Geotechnical Engineering Conference, 2008, at the University of Minnesota.

Jan 1, 2010

By A. S. Tawadrous

This paper is an evaluation of Artificial Neural Networks (ANN) as a tool in the design of the geometry of surface blast patterns. The built model uses eight different parameters, which affect the design of the pattern. Those parameters are rock type, stratification, blasthole diameter, bench height, type of explosive, priming position, powder factor and fragmentation size required. The network was trained to predict burden and spacing of the blast pattern. The model was built and trained (back-propagation technique) using 43 case histories collected from the literature. The model has then been validated using 16 cases from operational quarries.

Jan 1, 2006

By Ruilin Yang

This paper provides a theoretical analysis of shockwaves in an air-deck induced by detonation of an explosive charge and shows that the initial shock pressure in the air-deck at the interface with the explosive charge is only about 1% of the detonation pressure. A rarefaction wave with the low pressure travels back into the explosion detonation products greatly reducing the post-CJ detonation pressure. Additionally, AUTODYN modelling shows that the pressure attenuates further during shockwave propagation along the air-deck. Although the pressure increases at the bottom of the blasthole due to shock reflection, the overall pressure in an air-deck does not increase and is still around 1% of the detonation pressure which is too low to break most rock.

Jan 1, 2016

By Dale S. Preece, Ruilin Yang

Shock wave physics is an important part of air-deck behavior since the bulk explosives in the column impart a shock into the air-deck where the air shock then passes through the air-deck at a rapidly attenuating velocity. Through both high-fidelity modeling and shock physics theory it is shown that the resulting pressure in the air-deck is two orders of magnitude less than the detonation pressure of the explosive. The induced air blast reflects from the bottom of the borehole and this reflected pressure, even though doubled, is still approximately two orders of magnitude less than the detonation pressure. Air-shocks will ring back and forth in the air-deck for a few tens of milliseconds while the adjacent explosive column(s) are detonating. Transmission of the initial shock through the air along with reflections is an intensive energy consuming process. Energy balance results in shock heating of the air and a temperature increase. However, the increased temperature of the air is also orders of magnitude less than that of the explosive detonation products immediately behind the detonation front. Replacing high energy explosives with zero energy air-decks in a blasthole will always have a negative impact on the adjacent rock fragmentation and movement.

Jan 1, 2016

By Braden Lusk

Vibrations as a result of blasting practices in mining engineering are a complex phenomenon controlled by many variables. Mine blast vibration modeling and prediction is becoming more important as a consequence of interactions by mining activity with an ever closer public. Many communities (all over the world) close to mining activity often complain about airblast and vibrations produced from blasting activity. It is important for the mining industry to have tools and understandable methodologies to model and predict blast vibration. These tools can then be used to predict and control vibration at neighboring structures.

Jan 1, 2013

By Wang Hao

"Demolition of reinforced concrete frame structures in building crowded cities is a hardproblem in control blasting. Any mistakes, e.g. wrong toppling direction of multi-storeybuilding or incompleted blasting of structures will all cause terrible accidents.To demolishframe structures safely, various disciplines including structural mechanics, explosionmechanics, rock engineering, etc. are involved"

Jan 1, 1993

By William D. Hissem

The purpose of this paper is to advise people about the methods, use, and possible applications of current "personal computer" hardware and software with regard to the economic cost analysis of percussion drilling equipment. The material content and orientation of this paper is toward those people who have just begun "PC" (personal computer) operations, and (or) those who are considering their use.

Jan 1, 1986

By Karl Peterson, Bibhu Mohanty, Chanakya Nariseti

The mechanism of crack formation in two target rocks (Kuru granite and Flamboro Limestone) is studied experimentally by simulating the impact action of a percussive drilling bit. Rock samples are dynamically loaded using a custom made impacting bit (8 mm, 12 mm and 15 mm diameter bits). The target rocks are impacted at velocities 8, 10, and 12 m/s. The resulting crack patterns are visualized by three techniques, Dye penetration, CAT scans and Optical scans. Mapping of the crack patterns is manually done with Photoshop. For 3D damage visualization, the crack patterns are mapped in two planes (impact surface and longitudinal sections). The three techniques are compared to determine an optimum technique for better damage visualization. The evolution of crack pattern with impact velocity and bit diameter is discussed.

Jan 1, 2015

By Syed M. Tariq, Paul N. Worsey

Pre-splitting is now widely used to minimize overbreak and to protect final surface rock excavation profiles in large scale civil construction projects, open pit mining and quarrying. Jointing has been shown to affect the success of pre-splitting and the smoothness and integrity of the resulting rock face. Many facets of jointing have been investigated in detail, including the inclination of joints with respect to the desired pre-split plane, the effects of various filling materials, etc. However, the effects of joint frequency and spatial positioning has been paid little attention. The paper addresses this issue.

Jan 1, 1995

This case history refers to the detonation of the two largest chemical explosions on the Australian continent. An important element of feasibility studies and construction guidance included prediction of fragmentation results and ground vibration effects for the detonation of two very large "coyote" blasts, consisting of mined tunnels filled with explosives. The larger of the two blasts contained nearly 1 1/4 million pounds of explosives detonated instantaneously. The explosives were placed in specially designed tunnels under a quartzite mountain for the purpose of generating rock fill for the main dam on the project.

Jan 1, 1995

By Frank Barker

Mining operations present a very different environment to the suppliers of explosives, initiating systems and services, both on surface and underground. Typical hazards include underground movement, air quality, ground stability, moving equipment, and the use of explosives. As contractors to the mining industry we do not have management control over the environment in which our people operate. The hazards and consequent level of risk that our people are exposed to in some mining operations are significantly higher by orders of magnitude than in a normal factory environment. Orica Explosives (and other Explosives suppliers) are continually and increasingly identifying opportunities to partner with customers by adding value through the provision of services leading to a reduction in total mining costs. These services include the provision of a bulk underground loading services, delivery of product into underground magazines, magazine management, value added blasting, conversions, rock-on-ground contracts, and blast management programs.

Jan 1, 2000

By Michael S. Wieland

Delay detonators that are damaged by cross-hole wave interactions degrade blasting work and raise the risk of incidents. Damaged detonators impose risk, because they can retain sensitive explosives that respond to stray energy during recovery, inspection or disposal. Laboratory techniques were developed to rank the ruggedness of delay detonators under replicated field-shooting conditions. The hazards are tremendously magnified if trial detonators are installed directly in secondary explosives to rank initiation strength. Therefore indirect ranking techniques were sought that mitigate the risks without compromising the worthiness of the method. Four types of hardware fixtures, referred to as simulators, were developed to yield distinct forms of transient compression. The shock and rift versions generate compression pulses representative of in situ waveform components. The waiting time, until the trial detonator functions, duplicates typical delay periods. The trial detonator is mounted within water, which has a density and inertial resistance comparable to most blasting explosives. The work output from the trial detonator explosion is registered as fixture wall-expansion. This work output determines malfunction results, regardless of which type of simulator is used.

Jan 1, 1997

By M Sampara, W Comeau

The introduction of large-diameter holes to underground mining has made possible the development of new mining methods such as the Vertical Crater Retreat (V.C.R.) method. It is not only the safest underground excavation system but also provides mass production at a lower cost than any conventional mining method (1, 2, 3, 4, 5).

Jan 1, 1981

By Jack Eloranta

This paper compares energy requirements for blasting, crushing and grinding. By tracking electrical consumption for various powder factors, a general trend has appeared. This study involves over 100 million tons of ore and powder factors ranging from .5 lbs/LT to .8 lbs/LT. Actual energy usage is compared to predicted energy based on the Bond equation.

Jan 1, 1997

By Rolf Koenig

After the Dynatronic firing system was demonstrated for the first time at the SEE conference in Miami in 1987, it was officially approved in Germany at the beginning of 1993. Dynatronic has now been on the market for 5 years. At present, it is used in several European countries and successful test series have been running in Australia.

Jan 1, 1998

By Ken Eltschlager, J Silva Castro, J. M. Hoffman, Braden Lusk

This case study focuses on analysis of sounds inside a house induced by blasts as result of surface mining coal in West Virginia and how to better communicate technical information to the public. The field study included a house wide vibration and sound monitoring system installed in a home which was subjected to blasts at varied distances and direction. The structure response was separated into ground vibration and airblast induced movement due to the differences in their times of arrival. This signal was then compared to the sounds recorded to determine which component of blast (ground vibration or airblast) induced the maximum sound. Findings shows that blasts at distances less than 762 meters (2,500 feet) had maximum sound responses from both ground vibration and airblast. While for blasts beyond this distance the maximum sound response was caused by ground vibration without exception. The kitchen generally created the most sound. The second phase of the study was to gauge the public’s response or preference to technical information. Three hundred and forty eight (348) telephone surveys were conducted in Logan and Boone counties West Virginia. Based on the survey, the public prefers units of pounds per square inch (psi) for airblast and millimeters of displacement for ground vibration. Ultimately a public relations plan was developed based on the results.

Jan 1, 2012

By Robert Hopler

On June 13, 1912, the final decree of dissolution of the DuPont explosives trust was handed down, and the resulting new companies began operating at the beginning of the new year. The property assets granted to (or retained by) the companies were as follows:

Jan 1, 2014