Search Documents

By Michael Weaver, Dale L. Ramsey

The Pinkerton Tunnel open cut project is part of the National Gateway Clearance Initiative improvement project to achieve a minimum of 21 feet of vertical clearance along CSX Transportation rail corridor so that double-stacked intermodal railcars can be transported between mid-Atlantic states and their ports to midwest markets in the U.S. This project involved drilling and blasting of 1.2 million bank cubic yards of rock over a 14 month period while maintaining rail traffic of two passenger and 38 freight trains daily. See story and photos, page 6.

Jan 1, 2015

By Mark S. Stagg, Stephen A. Rholl

The U.S. Bureau of Mines has developed computer software which uses fast Fourier transform (FFT) techniques to evaluate blasting data. The software is useful because it allows blasters to evaluate 1) the frequency content of ground vibration time history data; 2) the effects of initiator scatter on the frequency spectra of ground vibrations; and 3) the fragmentation distribution of rock muckpiles from photographs. A one-dimensional version of the software was used in the first two cases. Monte Carlo techniques were used to simulate the scatter of initiators.

Jan 1, 1995

By Gregg R. Gitschlag

There are more than 4,000 oil and gas structures present in the U. S. Gulf of Mexico. Approximately 100 structure removals occur each year and 66% of these are removed with explosives. From 1993-1995 an intensive study was conducted on the fish kill resulting from the explosive removal of 6 platforms off the Louisiana coast in water depths from 14-28 m (45-92 ft). After explosives were detonated, all floating fish and a sample of the dead fish which sank to the sea floor were collected.

Jan 1, 1997

By H. S. Venkatesh R. Balachander, G. C. Naveen

During the construction of a 1020 MW underground hydroelectric project in Bhutan a huge rock fall took place in the Downstream Surge Chamber (DSC) during March 2016. The total quantity of rock in the fall area is estimated to be about 1,50,000m3 (2.6 billion cubic feet), out of which about 25,000m3 (0.44 billion cubic feet) of muck was removed. The removal of muck was stopped apprehending that the cavity formed due to the rock fall may get further aggravated leading to widening and destabilising the adjacent transformer hall cavern or it might day light as the top cover was about 190m (623 feet). As the fall has virtually blocked the 314m (1030 feet) long cavern and divided it into two different chambers (south and north), and that the muck cannot be disturbed, it was decided to erect concrete wall on either side of the fall up to the cavern roof and then later address the filling of the cavity with appropriate fill material. As the access to the DSC was there for the southern side it was decided to extend a cable tunnel which was terminated at a distance on the north side of the cavern by D&B so that once it gets punctured into the north wall of the DSC it can be used to access the fall from this front too. This is a unique situation where in every blast approaching the DSC, the parting between them is diminishing and hence the tunnel blast will be exerting axial load on the parting wall leading to dynamic transient loading conditions and buckling may take place on the northern wall of DSC. This paper describes the various drill blast combinations adopted for successful excavation of this tunnel.

Jan 1, 2019

By Jamie Delgado, Marco Arelano

The changes of bench angles in an Open pit mine has a strong economical impact in the “mining business”, particularly in its cash flow related both to the decrease as well as to the increase of the global bench angle or the inter-ramp angle. The global vision of bench optimization process currently developed by Compafila Minera Zaldivar (CMZ), includes the interconnection of different processes driving to the completion of the designs. Thus five very influential areas are recognised such as: (1) The physical Surrounding terrain, (2) the strength parameters, (3) the observational model, (4) the acceptability criteria and (5) the operational considerations. One of the important variables affecting this process is Drilling and Blasting (D&B). Increasing the bench angle requires to optimisation of D&B. To achieve this efficiently controlled sub processes must be defined. Three (3) steps can be defined: (a) design parameters, (b) explosive energy distribution and (c) operation results. To control and improve said steps quantitative evaluations of D&B must be performed. One valid evaluation is the “near field vibration monitoring technique” (at bench level). With the application of damage criteria, measurements and modelling of particle velocity a proper definition and optimisation of stages (a), (b) and (c) was achieved, The use of this methodology has enabled to CMZ to successfully increase the inter-ramp angle in three degrees thus obtaining a saving of US$ 36 million in the waste material removed. Also, the efficient control of the bench slopes has resulted in the improvement of the fragmentation operational results. This has resulted in a 26Oh increase in the ore processing by saving energy in the primary crusher due to its performance improvement.

Jan 1, 2001

By Catherine T. Aimone

A series of experiments have been performed to characterize fragmentation and microcracking in quartz monzonite copper porphyry. The flyer plate impact method was used to generate plane shock waves in rock specimens for impact pressures between 1.6 and 7.3 GPa and impact pulse durations between 1.1 and 7.0 µs. The effects of pressures up to 4.8 GPa and pulse duration on fragment size distributions and microcrack densities were studied. The results show that pressures effect particle sizes to a greater extent at higher pulse durations. However, changes in pressure and pulse duration show little influence on the density of microcracks induced during explosive loading. These results indicate that the nucleation and growth of microcracks in rock subjected to shock waves occur uniformly throughout. A substantial decrease in particle sizes for high pulse durations is attributed to more time allowed for microcracks to grow and coalesce, forming individual particles.

Jan 1, 1985

By M Dandeneau, P I. Rajic, K D. Murphy, M B. Johnson, T J. Tope

"Manufacturers and users of energetic material [i.e., propellants, explosives, pyrotechnics (PEP)] generate unserviceable, obsolete, off-specification, and damaged items that are characterized as reactive waste. These items must be safely treated and disposed of or reclaimed/recycled, thereby controlling existing waste inventories at manageable levels. The most commonly used disposal and treatment method, particularly at U.S. Department of Defense (DoD) installations, is open burning/open detonation (OB/OD). However, regulatory constraints and the inability of operators toobtain permits required for treating these waste has led to the recent reductions and limited use of OB/OD treatment at many installations."

Jan 1, 1995

By Frank Wilder, Mark Ferrero

One of the challenges currently facing the explosives industry is how to transition its workforce and its business systems to respond to the increasing pressures for improved inventory and records management. The pressures applied by many U.S. federal and state agencies, such as the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF) and the Department of Environmental Protection (DEP), as well as regulatory agencies around the world, are increasing the need for accurate inventory accounting of explosive materials and blast documentation. With blasting companies now facing regular documentation audits, potential liability issues may arise due to the inconsistent or missing documentation.

Jan 1, 2006

By MacDonald B. Johnson, Douglass P. Bacon

With the advance of science, rise of public interest in environmental matters, and continuing erosion of air quality, Federal and state regulators are demanding an increasing complex array of data concerning emissions produced by burning and detonating energetic materials. The U.S. Department of Defense, one of the world's largest consumers of energetic materials, now must characterize combustion products resulting from open burning/open detonation disposal operations. The catch-all phrase "below detection limits" no longer satisfies the regulators who now want testing to delve into the ppt level for volatile organic compounds and ppt level for semivolatile organic compounds.

Jan 1, 1995

By Eugene Baker

President George Bush signed the Safe Explosives Act (SEA), which amended the Organized Crime Control Act (OCCA) of 1970, into Law on November 24, 2002. As a result of this legislation, new restrictions on who could legally receive or possess explosives in the United States went into effect, resulting in a profound impact on the commercial explosives industry. The law went into effect in two key phases. The first phase, which went into effect on January 24, 2003, resulted in additions to the categories of persons who are prohibited from receiving or possessing explosive materials in the U.S.

Jan 1, 2004

By Robert B. Hopler

This paper reviews, from the historical standpoint, the development of the commonly-used terms such as "No. 6 and No. 8" with regard to detonator strengths. The origin of the strength terminology is reviewed, and the many methods developed to compare the strength of one detonator to another are described, with the good and bad points of each method outlined. The "miniature cartridge test," very highly regarded by both the U.S. Bureau of Mines and Institute of Makers of Explosives in the 1930's and early 1940's, is described in detail, as is a test developed and used by IRECO.

Jan 1, 1992

By Steve Dillingham

The origin of the written blasting log or shot report can likely be traced back to the earliest annals of blasting and record keeping. These records were, for the most part, a way of checking inventory, production progress, or billing, and not necessarily designed with the intention of being used as a legal document in a court of law. As our litigious society has evolved to include far reaching regulatory requirements, however, the blasting log has developed to support and aid in the defense of the common blaster from blasting lawsuits by providing a comprehensive written report of his or her actions.

Jan 1, 2002

By Catherine T. Aimone-Martin, Brent Meins

Blast vibration monitoring for buried pipelines is typically conducted at the ground surface with a shallowly buried geophone. In many jurisdictions across the U.S., blast-related vibration limits set for pipelines are dictated by surface measurements and do not consider the significant reduction of PPV amplitudes acting on the pipe at depth. This study involved a vertical array of geophones deployed in drilled holes at two blasting sites of the Loop 202 South Mountain Freeway construction project in Phoenix, Arizona. City of Phoenix pipeline engineers were concerned that blasting would damage an aged 48-inch (122 cm) prestressed concrete cylinder pipe (PCCP) that serviced water for South Phoenix

Jan 1, 2019

By Dave Weymer

Falling timber in BC has always been a hazardous job. Huge, often rotting trees and steep, rugged terrain combine to create difficult and dangerous conditions. Death and injury rates are among the highest of any occupation in North America. In BC, the men that head out, saw in hand, are called fallers.

Jan 1, 2013

By Michael A. Peltier, Dennis V. D'Andreal, Larry R. Fletcher

Accident data obtained from the Mine Safety and Health Administration (MSHA) were analyzed by the Bureau of Mines to determine the most frequent causes of blasting accidents in U.S. mining and to examine trends in blasting accidents. This accident analysis is an update of a similar blasting accident study conducted by the Bureau and published in 1983. The analysis shows that there has been a recent reduction in mine blasting accidents: The annual average number of nonfatal injuries has decreased from 107 for 1978-81 to 46 for 1982-85. The annual average number of fatal injuries was reduced from 11.3 to 5.0 during that time.

Jan 1, 1987

By Larry R. Fletcher, John W. Kopp

The safety record for explosives in U. S. mining is excellent considering that over 4 billion pounds of explosives are now being used each year. However, blasting accidents remain one of the most serious concerns based on the number of injuries, the injury severity rate and the disaster potential. The Bureau of Mines has been analyzing blasting accident data obtained from the Mine Health and Safety Administration (MSHA) to determine the most frequent causes of mine blasting accidents and to examine trends in blasting accidents. This accident analysis is an update of two previous blasting accident studies conducted by the Bureau and published in 1983 and 1987.

Jan 1, 1991

By Bill Birch, Toby White, Ian Brown

costs/benefits of electronic detonators and measure their effects on primary crusher productivity. 9 blasts (3 shock tube blasts, 6 electronic blasts). Measured electricity consumption & primary crusher throughput. Change to Electronic Detonators resulted in a 7% reduction in primary electricity costs and a 15% increase in primary crusher productivity.

Feb 1, 2020

By Mark S. Stagg, Rolfe E. Otterness, Farrokh Djahanguiri

The U.S. Bureau of Mines (USBM) evaluated empirical equations that predict fragmentation from underground stope rounds. Controlled blasting is necessary for creating leaching stopes that maximize the recovery and minimize backbreak of the perimeter wall. This paper presents the fragmentation results from one of the three drop-raise blasts used to develop a reduced-scale cylindrical stope, 1.8 m in diameter and 6 m in height. The stope is located in the Colorado School of Mines Experimental Mine (Edgar Mine) in Idaho Springs, Colorado. This stope is part of a USBM research effort to determine the feasibility of incorporating in situ leaching of rubblized stopes into active underground metal and nonmetal mines.

Jan 1, 1994

By Donald H. Matthews

I wish to preface my remarks with the warning that I, in no way profess to be an authority on the U. S. Department of Transportation, Hazardous Materials Regulations, 49CFR Parts 100-199, nor attempt to advise any one on the regulations or how they should conduct their business in relation to the regulations. I merely wish to convey my interpretations of the regulations and some of the procedures adopted by my company to comply with these regulations, with the hope that this information may help others to better understand the regulations and help them formulate their own procedures for compliance. I will cover nine problem areas and furnish sources of information for anyone concerned with explosives transportation.

Jan 1, 1977

By Ravi Sahu, 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.

Feb 1, 2020