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By James H. Redyke

In August, 1980, while finishing construction of the new stack, one of the flues mysteriously collapsed, killing three people and injuring several others. Several months later a British international steeple-jack company was hired to demolish the remaining portion and make a detailed inspection of the balance of the chimney. During this contract almost one hundred core samples were taken from all parts of the structure including the 32-inch thick base. As the result of these tests and the investigation, the Power Company decided to demolish the complete structure. Because of the critical time element, the decision was made to use explosives in the removal of the structure. To give you some perspective as to the size and dimension of the stack, it was 900 feet tall, 80 feet in diameter at the base, and 70 feet in diameter at the top. The two remaining flues were 25 feet in diameter and extended 30 feet beyond the top slab of the chimney. The outside of the structure was referred to as a wind shield. The lower 120 feet were 32 inches thick and the remaining 780 feet were 12 inches thick. The decision was made to prepare and shoot the chimney at the 120-foot elevation because the debris from the collapsed flue was confined in the base section and could not be easily removed. After extensive and costly engineering, we determined it was necessary to construct steel columns to bear on the lower 120-foot section, which would act as a hinge and guide during the dropping of the structure.

Jan 1, 1982

By Richard A. Dick

Few topics in the blasting industry are more controversial than the proper riming procedure for large-diameter ammonium nitrate-fuel oil (AN-FO) charges, despite the considerable amount of research that has been done both in the laboratory and in the field. The January, April, and June 1975 issues of Emphasis on Blasting contain interesting discussions on priming (5). An ideal primer is one that will surely and efficiently initiate the AN-FO column at the correct location to assure optimum blasting performance. During the 20 years of AN-FO's existence, singlepoint priming, axial priming, multiple-point priming, thermal priming, and shock riming have all been advocated as the "optimum" method. This is not surprising because blasting specialists have often differed on even the most fundamental concepts. To define the optimum primer, we must know what detonation characteristics in the AN-FO column are most desirable. Again, authorities disagree. This paper will discuss conclusions of various studies in an attempt to clear up some of the confusion.

Jan 1, 1976

By T Davids, O J. Jordaan, M D. J Bonneau

As in most other parts of the world, the surface coal mining industry in South Africa is introducing emulsion explosives as the primary bulk blasting agent for use in wet borehole conditions where AN/FO cannot be used. Most of the emulsion products presently in use are gassed to provide sensitivity. The intimate mix between the fuel and oxidizer in the emulsion has been shown to produce a highly efficient explosive. However, a major difference between emulsion and the previous slurry products is its relatively low physical strength. This prompted Rand Mines' Duvha Opencast Mine, a major South African Escom power colliery, to conduct test work to illustrate the effect of emulsion physical consistency on blasthole loading. This paper presents the results of test work conducted at Duvha to investigate the problems associated with loading both AN/FO and emulsion in water filled holes, stemming emulsion holes, and in particular, to illustrate the difficulty in correctly introducing a stemming deck into the emulsion column. Time dependent behavior of the loaded emulsion holes is investigated. Velocity of detonation measurements for freshly manufactured emulsion, and for emulsion after loading through water with sleep times of up to 10 days, are presented.

Jan 1, 1987

By Robert S. Mayo

Tunneling, for transportation, began in France with the Milpass Tunnel on the Lanquedoc Canal in 1680. Of course, the ancient miners had been driving tunnels in search of minerals since the dawn of history but this Milpas Tunnel was the first tunnel exclusively for transportation. In England in 1760, the Duke of Bridgewater opened a canal from his coal mines to Manchester, 10 1/2 miles away. At the mine, he drove a tunnel into the mountain so that the miners could shovel the coal directly into canal boats. James Brindley, an untutored genius, was his engineer and this whole transportation system was an instant success and very profitable through the years. Within a dozen years the Duke, again with James Brindley, opened up the Grand Trunk Canal, 139 miles in length with five tunnels. There was one major tunnel on this system, the First Harecastle Tunnel, 1 1/2 miles in length. But this tunnel was too small. It was only large enough for one 7-ft wide boat which had to be "legged" through by boatmen laying on their backs. By 1824 a second tunnel was driven parallel to the first one, but it had a towpath through it for horse haulage. This was the beginning of the " Industrial Age" and tunnels became a very important part of that era.

Jan 1, 1979

By D VanDoorselaere

"Image analysis techniques are widely used for blast fragmentation measurement, and various commercial packages are available for this purpose. These packages are very versatile and serve as a useful tool for optimization of blasting practice. But many times, the results provided by image analysis techniques do not match with sieved and predicted data. This leads to the suggestion that understanding the limitations of this technology is as important as understanding its usefulness and versatility.A study was conducted in two stages:(a) Comparison between the results of image analysis and screened data using laboratory scale muck piles.(b) Comparison between predicted (Kuz-Ram) and measured (Image analysis) blast fragmentation results for several bench blasts.During laboratory work, muck piles with known size distributions were analyzed with the help of image analysis technique. A disparity was observed between the sieved and measured results because the image analysis techniques cannot accurately determine the % of fi nes in the muck. During fi eld work about fourteen blasts were monitored. It was observed that predicted (Kuz-Ram) results rarely matched with measured (Image analysis) results. The Kuz-Ram curves were modifi ed by changing the rock factor so that the Kuz-Ram and Image analysis curves match in the vicinity of the 50% passing size. The pairs of curves (modifi ed Kuz-Ram and Image analysis) were divided into three categories depending upon their differences in the coarse and fi nes ranges. The blast design parameters affecting the difference between the pair of curves have been outlined. The suggestions have been made to better utilize the image analysis system."

Jan 1, 2007

By Abdulkadir Karadogan, Zikri Keti, Umit Ozer, Mehmet Aksoy, Ulku Kalayci

This paper presents an investigation about how the motions of blast induced vibration waves were affected by the presence of the fault planes. This study was carried out at Espey Open- Pit Boron (Colemanite) Mine in Turkey. Within the scope of the study, ground vibration components were measured for 8 shots using 9 vibration monitors, considering the direction of the fault. Measurement stations were located around the fault line that intersects the open-pit mine in the north-south direction and on different benches along the fault plane. Then, the data of the vibration components obtained from the 77 recorded events were analyzed and the results were presented.

Jan 1, 2012

By Brian Sandhuas, Robert McClure

All flyrock incidents have the potential to result in injuries or fatalities that can result in loss of company reputation, license to operate with clients, and bear the exposure to high cost liability. From 2007 to 2009, one North American Quarry and Construction Business experienced a series of flyrock incidents. In the spring of 2009, this business declared that the frequency and severity of Flyrock Incidents had reached an unacceptable level. A Flyrock Elimination Program was launched.

Jan 1, 2012

By Tuan Nguyen, Dirk Hummel, Ruilin Yang

In a tunnelling site in Japan, it was found that detonators failed to initiate with their shells and primary explosive intact. Their capacitors, however, were discharged due to some damage on the application-specific integrated circuits (ASICs). These detonators are distinctly different from other commonly observed failures, where the shells are rather crashed due to excessive dynamic pressure received from neighbouring blastholes which fired earlier. Such incident has not been reported elsewhere. Detonator failures during a blast are deemed not safe and can cause disruption on the project productivity. It is therefore desirable to understand the origin of such event. Various measurements were conducted to diagnose the problem, but the root cause had yet to be identified. This paper applies a discovery from a 60-year-prior-laboratory experiment and formulates a theory that could explain the observed detonator failure and predicts the measurements and observations.

Feb 6, 2023

By Benjamin Cebrian

Metallurgical testing at Cobre Las Cruces prior to production at the mill was done with overburden gossan. Some of that test gossan was a very fine material, wet by the water conditions at the bottom of the pit. When processed and stored wet at the fines material 3000 tonne (3307 tons) silo, this material cemented in a very unusual manner.

Jan 1, 2010

By John Petty, John Loviza

Single sentence describing content-- "The best ally an Explosives Engineer can have in a court of law is a regulations enforcer stating all codes and standards were met on a jobsite".

Jan 1, 1996

By Thierry Bernard

Today, experimental measurement of the shock energy/gas energy pair, or pool test, has now become virtually standard. But pool" energy per m(exp 3) of bedrock has no significance for explosives used in any medium other than water.

Jan 1, 1994

By Eduardo Gonzalez Fernandez, Jaime Rios Vazquez

This report substantiates the connection that always exists between explosives and vibrations and draws attention to low frequency vibrations, which are the moat dangerous for the structures affected.

Jan 1, 1986

By Gerard O'Brien, Douglas Comstock

"The construction of the Third Harbor Tunnel is the first major portion of the Central ArteryProject. The tunnel is designed to connect South Boston to East Boston to alleviateautomobile congestion through the downtown area. The 4000' long tunnel traversesBoston harbor as a cut and cover tunnel as opposed to a bored tunnel."

Jan 1, 1993

By R D. Skaggs

A good blast is dependent on a well engineered design. However, a good design's performance depends on the control of the drilling and loading of the blast holes. The key stone to good blasting is the drilling of straight holes of the correct orientation in the required positions.

Jan 1, 1991

By Jim Daley

This case history discusses a pre-split test conducted at BHP Mineralss Navajo Mine in Fruitland, New Mexico. The test was an extension of earlier pre-split testing conducted by Virgil Stachura of the U.S. Bureau of Mines in conjunction with Navajo Mine and WESCO Inc. which tested low-density product in 10.625 diameter holes.

Jan 1, 1996

By Cam B. Grundstrom

This paper will describe blast design modifications that have been made at the Island Copper Mine, near Port Hardy, British Columbia. To date, two additional designs have been implemented in an effort to reduce final wall damage and increase productivity. The typical blast patterns in use at Island Copper were monitored in an effort to build up data to which new designs could be compared.

Jan 1, 1994

By A N: Zditovetsky Shishov, M G. Menzhulin

At present in a building industry demand for products from granite, gabbro and other rocks, steady to erosion, natural and chemical weathering, was essentially increased. It has caused the enlargement of exploitation of stone block deposits and necessity of creation of new technologies of hard stone cut.

Jan 1, 1996

By H J. MacDonald

An Exploding Bridgewire Detonator (EBW) is an explosive initiator which contains only secondary explosives such as PETN and RDX. It is safer than the normal blasting cap because it requires both high electrical energy and a very fast application of that energy to function

Jan 1, 1981

By Thad M. Jones

This paper considers the sampling, digitizing and reconstruction of seismic signals. A sampling frequency range is proposed and a minimum limit is suggested. Digitizing precision criteria for both peak velocity and analysis applications are given. Several methods for reconstructing signals from sampled data are presented.

Jan 1, 1985

By E E. Cloete, R I. McCrindle

Permitted explosives were previously nitroglycerine based and cap sensitive. Due to safety, health and environmental requirements, water-containing explosives, such as watergels and emulsions, were used instead. However, in order for these explosives to perform at their designed level during blasting, a more powerful stimulus than is delivered by detonators on their own is required.

Jan 1, 1999