Search Documents

By F. Schott, M. James, G. May, E. Baker, C. Johnson, R. Bauer

Explosive demolition typically utilizes cutting charges to sever columns, detonating cord to time charges and provide an initiation path, and dynamite as a kicker charge. The kicker charges of dynamite are used to “move” columns out of alignment, causing collapse. Demolition projects involving dynamite can pose significant health and safety risks to workers and the public. Nitroglycerin in dynamite can cause dizziness, fainting, and other health problems. Moreover, dynamite placed directly on columns can result in fragmentation and cutoffs, preventing other charges from being initiated and resulting in incomplete demolition. Fragmentation can occur from columns and travel significant distances from the initiation point, sometimes reaching hundreds of meters away. This fragmentation can pose serious dangers to anyone in the vicinity, including workers and members of the public, as the debris can cause severe injuries and property damage. The force and velocity of the fragmented material can be unpredictable and difficult to control, making it important to take proper safety precautions and consider alternative demolition methods that minimize the risk of fragmentation. Previous work concluded that casing charges in water showed that a reduced dynamite charge mass could still successfully kick the charge out of alignment. This study aims to investigate the use of Pentolite boosters in water-cased charges as a safer alternative to dynamite-based demolition. The research involved testing various amounts of dynamite and pentolite boosters in water to compare their effectiveness in moving a hanging W-beam, which swung freely like a ballistic pendulum. Water-cased charges consistently move the column at a higher velocity than the traditional dynamite charge placed directly on the column. The method of water-casing increased the area of impact and impulse felt by the column, improving demolition efficiency when compared to traditional demolition methods as found in previous studies. Pentolite water-cased charges moved the column at 7.8 meters/second (m/s) while the dynamite water charge moved the column at 5.9 m/s. The increased strength and explosive properties of the pentolite contributed to this increase in velocity. This study showed that it is feasible to remove dynamite from demolition projects by utilizing pentolite boosters and that when considering safety, explosive properties, and effectiveness, pentolite boosters can be cost effective as well.

Jan 1, 2024

By Lon Santis, David Leidel, John Tatom, Meredith Hardwick

This paper describes the development and methodology of the Institute of Makers of Explosives’ Safety Analysis for Risk (IMESAFR), a risk analysis software program for commercial explosives operations. IME is a nonprofit safety and security association devoted to the safe and secure manufacture, transportation, storage, and use or disposal of commercial explosives in the US and Canada since 1913. The software methodology’s basis is the U.S. Department of Defense Risk Based Explosives Safety Criteria Team’s Safety Assessment for Explosives Risk (SAFER) software. A diverse group of industry and government experts contributed to modifications to SAFER that reflect commercial operations. IMESAFR is intended to supplement the American Table of Distances (ATD) and offer standardized methods of managing risk from a wide variety of commercial explosives operations where the ATD does not apply. The modifications made to SAFER primarily involved the addition of commercial activities and potential explosives sites (PES). A review of commercial explosives accidents and operations over the last 20 years served as the basis for establishing probability of event values. An industry survey of commercial PES types in the U.S. and Canada was conducted to identify and address critical differences in commercial structures as compared to the military structures in SAFER. The paper concludes with discussion of the potential uses for quantitative risk analysis (QRA) and a description of other explosion effects software

Jan 1, 2007

By W. Jiao, Y. Yongqi, R. Shan

Soft rock mines are distributed through out P.R.C. And drilling and blasting is still the main method of driving a tunnel in these mines. Traditional smooth blasting has been widely and deeply studied and put into practice in P.C.R since 1970s. But the cartridge and blast hole are both columns, the stress field in the rock around blast hole at the beginning is symmetry around hole axis, and the original cracks in the rock can be activated randomly. So serious overbreak and underbreak at the boundary of an excavation occur often, especially when the excavation is in soft rockmass, and the rates of half-hole marks are generally about 50% in medium rock, and 20-30% in soft rock in Chinese coal mines. For the sake of overcoming the situation, we have been studying directed crack blasting since ten years, and have got some obvious achievements in this respect. Slotted cartridge control blasting in soft rock is studied in this paper. Through model experiments, reasonable decouple coefficient range and slot width are gotten, and unsymmetrical dynamic strain field is analyzed. Through underground test in soft rock with a strength lower than 1OMpa in Dayan Mining Bureau, The results of which the rates of half-hole marks and the nonsmooth grades of the cut contours are 83.3% and 1OOmm respectively have been achieved.

Jan 1, 2000

By Adrian J. Moore, Alan B. Richards

Airblast overpressure levels can commonly be increased by up to 20 decibels (dBL) by the effects of meteorology, due to inversions and wind shear. Existing atmospheric refraction models can provide a good evaluation of the effects of meteorology, but have been limited in the accuracy of their outputs by the accuracy of the meteorological data that is available for input. This paper uses case histories from open-pit coal mine blasting in the Hunter Valley area of Australia to provide examples of increases in airblast due to inversions, wind shear, and a combination of both. It gives details of our experience of the accuracy with which predictions and assessments can be made using meteorological data of various levels of accuracy, and on the design buffer that is required to prevent the exceedence of airblast limits. The accuracy of meteorological prediction and assessment will shortly be improved by the use of sounding equipment that gives continuous measurements of temperature and wind velocity at significant levels above the ground. The paper also gives details of an industry funded research project that aims to permit the effective use of this data at distances many kilometres (km) (miles) from the location of the sounding equipment, and to develop a short term predictive model that will permit the amount of meteorological reinforcement that will occur at firing time to be determined before a decision is made to tie up a shot.

Jan 1, 2005

By Ray Jambakhsh, Gabrielle Bourget

In the summer of 1998, Ontario Hydro awarded a contract to demolish an obsolete and inefficient chimney by blasting. The Ontario Hydro Thunder Bay Thermal Generating Station (T.G.S.), is a fully operational hydro thermal generating station located in Thunder Bay, Ontario, Canada. The Chimney was a 356 ft (108 m) high freestanding structure constructed of reinforced concrete with a brick liner. Falling the chimney required careful planning due to the highly sensitive structures and equipment which surrounded it. Damage either sustained to the existing systems through ground vibrations or direct contact would have resulted in expensive power outage and/or lost production. The role of Explotech Engineering Ltd. on this project was to provide and evaluation of the proposed demolition procedure, defme the predicted and maximum seismic vibrations at sensitive structures including underground services, conduct pre-blast / post-blast inspections and recommend various safety precautions. The general contractor for the project, LeBrun Northern Contracting Ltd., of Thunder Bay, Ontario was responsible for all site preparations and post-blast clean up. All demolition blasting calculations and operations were conducted by Dykon demolition experts from Tulsa, Oklahoma. On September 13, 1999, the chimney was successfully demolished. Extensive analysis of the vibration records and visual post-blast inspections of the surrounding structures concluded that the demolition event induced no damage to any of the Ontario Hydro facilities.

Jan 1, 2000

By Zou Dingxiang

Rock blasting in the project of “Site Formation and Associated Infrastructure Works at Choi Wan Road and Jordan Valley” is the largest urban blasting project in the history of Hong Kong and also is rare in the world. More than 6.2 million of in-situ rock has to be excavated by blasting. The site is located in the center area of eastern Kowloon peninsula, surrounded by highways, registered cut slopes, high-rise residential buildings, MTR subways and the public utilities. The complex situations bring great difficulties and risks to the blasting works. A bird-view photo of the site is shown on Picture 1.

Jan 1, 2007

By Enrique Munaretti, Cathy Aimone-Martin, Vitor Rosenhaim, Jair Koppe

Production blasts at one of Copelmi’s coal mine operations will be carried out 100 m (330 ft) from a neighborhood located in the town of Butiá, southern Brazil. Mine management is concerned about the possibility of damages and complaints due to blasting operations at close distances to structures of substandard construction. Blasting in the area is characterized by the use of very low powder factor resulting in confined shots in which movement is restricted to a point of almost undershooting the rock. Over the past year, tests were conducted mainly in the overburden area to determine the best approach to be implemented when blasts move closer to the town. Mine management wants vibration levels to be reduced lower than the damage limits proposed by Brazilian regulations to ensure a safety margin and mitigate perception by the community hoping to reduce the number of complaints.

Jan 1, 2013

By Khushaal Popli, Vanessa Roeland, Brian Hall, Carl Diederichs

Highland Valley Copper (HVC) has embraced an integrated Mine to Mill approach to comminution since the late 1990s. Previous blasting optimization was carried out through adjustments to blast pattern geometry (i.e., reduction of burden and spacing). This approach proved very effective and HVC reduced the burden and spacing of high energy ore blast patterns to what was considered the practical limit that still allowed for efficient drilling and bulk truck loading operations. While mining in the bottom of the Valley pit near the end of the previous pushback, HVC encountered high static groundwater conditions which enabled the transmission of elevated inter-blasthole pressures that had the potential to exceed safe operating limits for initiation products. This risk was mitigated through an expansion of burden and spacing for the high energy ore patterns, reducing the application of blasting energy and increasing the average particle size in Mill feed.

Feb 6, 2023

By Ricardo Dr. Chavez, Mathieu Lachamp, Rob Dr. Farnfield

Pueblo Viejo is an open pit gold mine in the Dominican Republic which is always looking forward to implement the newest technology in the industry to improve all processes. Focusing on one of the pillars of the department and our company, digitalization, we’ve been looking for the technologies that allow us the automation of data generation, supervision and process innovation. That’s where a new Drill and Blast software takes place, helping to integrate the process from the beginning to end, right after the pattern is designed until it’s blasted, allowing us to track results like vibration, fragmentation, performance, cost and inventory of each blast in a single platform. The software helps engineers to generate back analysis by blast, bench, pit, month and many other ways, in a timely friendly manner. Therefore, we can catch business opportunities and improvement for the drilling and blasting process.

Jan 1, 2019

By Dale Preece, Stephen Chung

Mining and quarrying industries recognize blasting as the most effective method for breaking and removing large volumes of rock. However, the economics of blasting are often offset by the costly trial-and-error approach. Researchers in the field of blasting therefore design models to help eliminate the number of trials before finding the best feasible solution. Because of the complexity of blasting, a capable model would allow the designer to look at more than one variable at a time so that the most critical factor can be tackled.

Jan 1, 2002

By Ed Jr Smith, Calvin J. Konya

The purpose of this paper is to describe the case history of a blasting project conducted jointly by Precision Blasting Services and Cherokee Explosives. It is the intent of the authors to show how blasting could be done in controlled fashion near very expensive computer controlled machinery. The job was done in minimal time with no complaints or allegations of damage in spite of the fact that blasting was conducted within five feet of the equipment and with the 32 acre plant fully operational, with machine operators working within 10 feet of the blasting site.

Jan 1, 1986

By Calvin J. Konya

The Woodville Lime and Chemical Company Limestone Quarry is located in Sandusky County, Ohio. Fifty years ago, when quarrying began, it was situated approximately two miles from the town of Woodville. Today new houses border the quarry property within 1,500 feet of one of the working faces. During the past two years, the operation has systematically changed the blasting program to achieve better fragmentation, lower costs, and to maintain good relations with the local property owners. This paper will discuss systematic changes made in the blasting program to increase productivity and reduce costs.

Jan 1, 1977

By RR Vandebeek, A W. Bauer

The Canadian Explosives Research Laboratory regularly evaluates the properties of commercial explosives for authorization under the Canada Explosives Act. Propagation sensitivity is normally measured using small scale tests. Relating the results in actual mining practice is difficult. In the mining industry, the propagation sensitivity is a measure of the ability of one cartridge to propagate to an adjacent cartridge in a borehole. They may be separated by a gap of in-filling material. As well the propagation sensitivity will be affected by the explosive type, temperature, degree of coupling, cartridge diameter and other factors.

Jan 1, 1987

By Greg Mclellan, Mark Johnson, John Pepper

In this paper, the measured vibrations are plotted in terms of the individual PPV components versus Scaled Distance (SD) on logarithmic scales. The maximum PPV is pIotted on a separate graph and equations are presented to predict the maximum PPV based on sealed distance and prediction level usmg power fits. The prediction levels include a 99.9% curve, which encompasses the data points and provides an envelope formula for determining the maximum PPV at South Florida sites. The dominant frequency distribution is established for the PPV components.

Jan 1, 2001

By Courtney W. Shea, Dennis Clark

Reckless blasting can have tragic consequences: The death of an innocent traveler, the financial demise of a coal company, and even criminal prosecution. In June 1993, a Tennessee coal mining company was blasting to loosen overburden at its surface mine. The mine was located immediately adjacent to the right-of-way of the northbound lane of Interstate 75. The approved permit included special precautions to be taken when blasting in the area closest to the interstate, including monitoring traffic so as to blast when the northbound lane was clear.

Jan 1, 1998

By Ingvar Hansson, Bjorn A. Jonsson, Bernt Larsson

In the Kiruna Research Mine, Sweden, four large open stopes have been mined, leaving intermediate piIlars and crown pillars. At the final stage of mining mass blasting of the crown pillars above two of the stopes was carried out. The crown pillars contained some 290,000 tons of iron ore. In the mass blast a new initiation technique was used, utilizing the new non-electric system NONEL ? UNIDET. The blasting technique including vibration control is described. The mass blast resulted in high recovery, good fragmentation and low vibration levels.

Jan 1, 1986

By R Holmberg, C Sjoberg, B Larsson

This paper describes the excavation of an underground naphta storage facility at Stenungsund in Sweden. The main purpose with this paper is to give an overall view of how the excavation was carried out and in what type of bedrock the storage was built. Emphasis has been done to highlight the importance of using cautious blasting to avoid blast damage in the remaining rock. Attempts has also been done in order to evaluate what the degree of Swedish cautious blasting has meant for the rock support costs during the construction period.

Jan 1, 1984

By David Hersey

The Paseo Bridge was located at the I-29/I-35/US-71 Missouri River Highway Crossing. It was built between 1952 and 1954 by Massman Construction Company. The 1,232 foot long, self-anchored suspension bridge was the longest of its type when built. On Jan. 22, 2003, a connector pin designed to allow the bridge to expand and contract during temperature cycles seized and caused a portion of the bridge deck to raise up and block traffic. This marked the beginning of the end for the old Paseo Bridge.

Jan 1, 2013

By Cathy Aimone-Martin, Frank Achuff

The New Mexico Department of Transportation (NMDOT) and the Federal Highway Administration (FHWA) have let a contract to Sierra Blanca Constructors for a design / build contract along 38 miles US 70 in Lincoln County, New Mexico. The project will improve safety of travel along the corridor and facilitate the adopted economic development goals of the state. Proposed improvements include widening the existing highway from two lanes to four lanes, providing left turn lane options at selected locations, improving access for businesses and residences, aesthetically enhancing retaining walls, improving storm drainage and replacing the existing pavement with a 30 year mechanistic imperialistic perpetual pavement design. The US 70 Hondo Valley highway project is situated in a narrow valley with steep limestone walls, passes along a Scenic Byway and numerous historic ranching communities with structures that date back three centuries. The scope of work included requirements to monitor and mitigate blasting, noise, and vibrations. The contract was very presumptive with regard to blasting design and procedures. These included visual impact mitigation to treat and stabilize slope cuts, the Migratory Bird Treaty Act protecting roosting and nesting birds from airblast, and the protection of historic and cultural features such as acequias, wells, and structures. Public involvement affecting the rock blasting design has come from citizen task forces and committees concerned with highwall aesthetics and preserving the scenic byway and cultural resources. Constraints placed on the blasting program from agencies and the communities are often at odds. For instance, blasting must produce stable yet natural-looking walls to preserve aesthetics. Restrictions have been placed on pre-splitting and smooth-wall blasting yet safe slope are of the highest priority. This paper presents details of the design/build process undertaken by the contractors to conduct blast rock in an environmentally sensitive region. Blast designs consistent with good construction practices and used to comply with the many federal and state highway stipulations are described.

Jan 1, 2004

By Jair Alarcón, Lucas Steffen, Leopoldo Muñoz

Flyrock is one of the most significant hazards associated with blasting in open pit mining, especially for blasting operations near communities. Flyrock can lead to severe injuries, fatalities, and property damage, compromising the license to operate. For this reason, defining exclusion zones is critical to ensure the safety of people and equipment. A very large radius will reduce the risk of flyrock; however, excessive exclusion zones can significantly impact the productivity of the operation and, in some cases, compromise the extraction of ore in critical sectors. Many mine sites use distances derived from pre-established standards, experiences from other mines, or still use simple methods for analysis, like recording blasts with a terrestrial camera and performing deterministic calculations to determine exclusion areas, applying an arbitrarily safety factor for people and equipment. In this paper we present a new approach that allows the calculation of the exclusion zone by measuring critical flyrock parameters with a high degree of accuracy through a new video analytics technology, this data then is used as input to calibrate probabilistic flyrock models to have more robust calculations, allowing optimized and safe exclusion zones. The proposed methodology leverages high-accuracy data and continuous monitoring to dynamically adjust D&B designs and exclusion zones, ensuring maximum safety without unnecessarily restricting operational efficiency. A case study is presented where the application of these new digital technologies allows precise prediction and control of flyrock trajectories, enhancing the accuracy of exclusion zone boundaries. In this case we successfully reduced the exclusion zone radius to 100m, allowing the ore extraction in a critical region close to the community safely. The study shows notable improvements in safety and productivity, including zero flyrock incidents and enhanced protection for nearby communities. The adaptive nature of these digital tools offers scalable solutions for various blasting environments. The paper concludes by recommending the integration of these tools into standard blasting protocols, highlighting the potential for widespread adoption in the industry to mitigate flyrock risks effectively.

Jan 21, 2025