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By R. F. Favreau, Patrice Favreau, Dennis Mahan

Cast blasting is becoming more and more popular, not only in coal mines but also in other operations which require excavation of an upper layer of waste rock to uncover temporarily and excavate a layer of ore, which may for example be material for the fertilizer industry.

Jan 1, 2014

By Dennis L. Paisley, Thomas P. Turner

Laser slapper detonators are the next generation detonator under development at the Detonations Systems Group at Los Alamos National Laboratory and function very similarly to an electrical slapper. A fiber optic transmits a laser pulse to ablate a thin metal film. This film, or flyer as it is commonly called, is launched through a short barrel to km/s speeds. The flyer shock loads or slaps a high density pressing of secondary explosive, setting off a detonation therein. Laser slapper detonators afford a number of safety advantages over other conventional detonators. Most important they require very high peak laser powers to operate, orders of magnitude larger than possible sources of natural or man-made accidental stimulus. Because light is transported over fiber optics, laser slappers avoid many of the electrical hazards associated with detonators. Use of insensitive, secondary explosives makes these detonators safer to handle, manufacture, transport, and deploy.

Jan 1, 1994

By Jean-Guy Levaque, Robert Ethier, Ron J. Elliot

This paper presents data gathered during a comprehensive study on the impact of improvements to fragmentation in a major Limestone quarrying operation. The full impacts of gains in fragmentation are tracked through the mucking, crushing, and grinding phases of the operation.

Jan 1, 1999

By Robert Morgan

With improved methods for designing and detonating shots the potential for flyrock can be significantly decreased, but there are few absolutes in blasting; therefore blasters must learn from the mistakes of others. Blasters must conscientiously employ control measures to minimize the risk of flyrock. The worst case incidents which tend to be widely reported by the media, should serve as a reminder to us all that minimizing the risk of flyrock must be incorporated into the design of the drill pattern and blast design.

Jan 1, 2001

By Martti Hagfors

The Finnish Defence Forces Technical Research Centre (PVTT) studied the effect of shape of boost-er to its ability to ignite insensitive (IM) plastic bonded explosive (PBX). Therefore an explosive fac-tory produced 20 insensitive (IM) plastic bonded explosive (PBX) charges for the tests. The mass of each of the charges was exactly 9.2 kg (20.3 lb). The charges were equipped by two different type of boosters; RDX and PETN. Both the explosives contained some parts of plasticizers. The weight of all the boosters was exactly 300 g (0.66lb). On the bases of their shape, the boosters were also divid-ed into two different groups, cylindrical and “pancake”. In the middle of the “pancakes” there was also shaped a small cone in such away that the detonation could accelerate to its full speed after the charge was ignited. The following shots were exploded;

Jan 1, 2013

By Scott Orenstein

Construction blasting has allegedly been the cause of property damage in the following situations: (1) When the detonation of the shot hurls rock and debris into the air that causes property damage upon impact; and (2) When property owners notice cracks in their walls and foundations after they experience the momentary vibrations that coincide with the detonation of the shot. The current state of the law for both these situations is firmly established. Blasting is classified as an abnormally dangerous activity, for which the blaster is held strictly liable, whether the damage is the result of flying debris or vibrations and concussions generated by the blast. It is when the alleged blasting damage is supposedly from concussions and vibrations, however, that the courts usually reach the wrong result. The typical scenario involves property owners that thoroughly investigate their property after feeling blast generated vibrations, and find cracks that they believe did not exist beforehand. Most often the truth is that the property owners have never noticed these cracks before because they have never looked that closely before. Any structure has a certain number of cracks due to a variety of causes, such as settlement overtime and temperature and humidity changes.

Jan 1, 2004

By Ali Kahriman, Alper Celtikc, Serdar Celik, Tuncer Gungor

This paper presents the results of ground vibration measurements carried out in Gülyali Hisarcik Basalt open pit mine located on the north side of the Anatolia near Ordu province in Turkey. Within the scope of this study in order to predict peak particle velocity level for this site, ground vibration components were measured for 5 shots during bench blasting. In blasting operations; ANFO (blasting agent), gelatin dynamite (priming) and delay electric detonators (firing) were used as explosives. Parameters of scaled distance (charge quantity per delay and the distance between the source and the station) were recorded carefully and the ground vibration components were measured for all blast events using 5 different vibration monitors (4 White Mini-Seis and 1 Instantel Minimate Plus Models). The absolute distances between shot points and monitor stations were determined using GPS. The equation of square root scaled distance extensively used in the literature was taken into consideration for the prediction of peak particle velocity.

Jan 1, 2013

By C. Pelley, S. Kelebek, P. D. Katsabanish, M. Pollanen

A series of small scale tests have been conducted to evaluate the effect of blasting on the grinding resistance of rocks. The samples consisted of homogeneous blocks of granodiorite and limestone while blasting was performed using single and multi hole configurations. Grinding resistance was evaluated using relative ball mill tests, rod mill tests and the SAG Performance Index test (SPI) developed by Minnovex. It was shown that the grinding resistance was affected by blasting. However the effect depended on the final product size. In the case of the coarse grained granodiorite, a negligible effect was observed for grinding below the natural grain size of the rock, while the fine grained limestone exhibited more significant changes, in the range of 13-16%. Grinding of granodiorite in the coarse size range indicated a general reduction of its work indices, as evidenced by the results obtained from the ball mill, the rod mill and the SPI tests.

Jan 1, 2004

By A. Karadogan, G. Tuncer, A. Kahriman

Determination of optimal blast parameters have been the priority act for blasters on the field due to financial and technical properties of the operation. Therefore many researchs were done to establish a general formula for many years. These intends could reach some empirical and numerical design frames consisting the rock, geology and explosives properties. Blasting parameters have to be adjusted according to the desired fragmentation rate especially on the mines where particle size distrubition after blasting has a great importance. Therefore the blast designs have to be evaluated considering the particle size distribution after the blasts. The Kuz-Ram model which was modified by Cunningham is one of the tools for estimating the particle size. Although it doesn’t give an accurate result, it can be very succesful on modifying the blasting design parameters by establishing a back correlation between the blasting parameters and the exact particle size distribution results which can be easily achieved by digital image processing system. Within the scope of this study, the particle size distribution after blasting was assessed by Split-Desktop digital image processing system and bench blasting parameters were studied considering the desired particle size distribution at Espey colemanite mine using Kuz-Ram and digital image processing system combination to determine the specific blasting parameters for this site.

Jan 1, 2005

By E. Contestabile, R. von Rosen, R. Guilbeault, R. Fouchard, P. Lightfoot

In August 1998, a truck loaded with 18 tons of blasting explosives, including over 13 tons of ANFO, left the road near Walden, Ontario. The crash caused a fire; approximately 30 minutes later a large detonation occurred, causing substantial damage to the roadway and local property. Although nobody was injured in the explosion, the consequences of a similar incident in a heavily populated area could have been catastrophic. Following the Walden incident, Transport Canada and Natural Resources Canada embarked on an extensive experimental program to determine the cause of the detonation. This paper describes part of that experimental program, designed to understand better the thermal decomposition of ANFO.

Jan 1, 2003

By Dale S. Preece

The computer program. DMC Qistinct Motion &de), which w&s developed for simulating the rock motion associated with blasting, has been used to study the intluence of row delay timing On rock mOtiOn. The munerical simulations correspond with field observations in that vmy short delays (< 5Oms) and vety long delays(> 3oOms) produce a lower percent-cast thao a medium delay (100 to ZOO ms). The DMC predicted relatio&lp between row delay timing and percent-cast is more complex than expected with a dip in the auve where the optimum timing might be expected. More study is required to gain a full undasranding of this phenomenoo.

Jan 1, 1994

By Nils Heinke, Stephen M. Collinsorth

To anyone who is responsible for the production of blast holes, who is looked to on a daily basis for drill maintenance and performance, whose bottom line may depend on the survival of the mine itself.. How much awareness should one have on such things that truly impact production, maintenance and overall job cost? Do you know your drill’s maximum capacity?

Jan 1, 1998

By Gungor Tuncer, Ali Kahriman, Abdulkadir Karadogan, Umit Ozer, Kagan Ozdemir

In the condition that drilling and blasting technique is inevitable depending on the rock mass and material characteristics on mining activities, the fragmentation rate and particle size distribution of the muckpile after blasting has important influences on the performance of subsequent mining activities such as loading, hauling, crushing, grinding etc. and the total costs of that mine. Drilling and blasting is an important step in this process chain and it's results such as fragmentation, muckpile shape and looseness, dilution, damage and rock softening effect the efficiency of downstream processes. There is an increasing body of blasting research indicating significant impacts in these downstream processes.

Jan 1, 2007

By Roberto Folcht

The obligations of the European Directive 96/82/EC on the control of major accident hazards, the so-called Seveso II Directive, became mandatory within the E u ropean Member States February 3, 1999. Explosive products have been included within the Seveso II Directive, in the categories of substances capable of generating a major accident. In addition to taking “all measures necessary to prevent major accidents,” explosive manufacturers are also obliged “to limit their consequences for man and the environment.” However, for explosives in particular, no pro c e d u res, nor specific re f e rence values for damage calculation, are given either in the Directive or in the corresponding Italian Legislation, “Ministry of the Environment decree of 20 Oct. 1998.” This article presents a simplified but scientifically rigorous approach for the first approximation calculation of the effects on the surrounding area following an accidental explosion. As an example of the method of calculation, the damage areas in a hypothetical explosives manufacturing facility, as shown in F i g u re 1, will be anal y z e d . The method proposed in this article can also be used for the analysis of explosions of gas in tanks or pipelines,

Jan 1, 2004

By Joseph Daly

An investigation into inaccurate scatter of pyrotechnic detonators led to the innovation of utilising existing (every day) equipment in a manner to accurately determine the true scatter of detonators. This can then be utilised to determine the accuracy of a particular batch of detonators.

Jan 1, 2014

By B Mohanty, G Yamin

A number of parameters, aside from blast design and pre-existing rock conditions, can change the performance of the explosives system in actual blasting practice. Sympathetic pressures caused by detonation of preceding holes have been identified as a major contributor to explosive system malfunctions, leading to uneven blasting performance. These effects can occur both within a hole or across several holes. These can consist of high transient pressures related to the shock phase of the explosion or the relatively longer or quasi-static pressures associated with the explosion gas expansion phase. This study presents the findings from an on- going investigation on measurement and analysis of these pressures between donor and receptor holes in a granitic outcrop for representative inter-hole distances and borehole conditions, employing single cartridges of emulsion explosive in 45 mm diameter holes. The results, despite wide scatter in the measured values, show the very short duration pressures to range up to 7 MPa and arriving within a few milliseconds after detonation, whereas the much lower amplitude pressures arrive after tens of milliseconds. Both have the potential to seriously affect the performance of an explosives system.

Jan 1, 2005

By Dave Otto, Ron Elliot, Ed Hatch

This paper is a summary of the work carried out by an international team of specialists in the successful explosive compaction of the sand fill core of the Molikpaq offshore oil production structure. The sand fill core is an essential element for the stability of the structure. The sand core must resist liquefaction forces caused by heavy wave action, ice loading, and earthquakes. Explosive compaction methods were used to improve the stability of 220,000 cubic meters of coarse dredged sand placed in the core area. This project was challenging for a number of reasons. It was performed offshore in Russia, seven kilometers off the East Coast of Sakhalin Island. Logistics were a challenge, not just in getting the men and materials to the site, but also working with restricted headroom inside an operating oil drilling platform. This project called for the use of specialty explosives, strict blast vibration controls requiring a complex sequential blast design, and use of custom designed drill rigs. As Russian equivalent explosives were not available, the project involved getting approval for use of North American explosives in Russia, and use of a combined Russian - Canadian blasting crew. The blasting program was carried out successfully, meeting the required densification target _in a safe, effective manner, with no damage to the structure.

Jan 1, 2000

By Stanton Johnson

Africa has a long history of mining and has been one’of the world’s greatest sources of gold and other mineral resources since the days of the Egyptian pharaohs. Mining in Africa has been dominated by South Africa since World War II. However, in the past 10 to 15 years, other African countries are beginning to slowly catch up with South Africa. Ghana, formerly called the “Gold Coast” is located on the West Coast of Africa. Ghana has been involved in mining activities for well over 100 years. Most of the mining activities centered on the mining of gold and were to a large extent limited to underground mining methods. With a more liberal economic policy regarding the exploration and exploitation of Ghana’s mineral resources, mining activities are beginning to evolve to a much larger scale. Drilling and blasting which is an important aspect of this evolution is also changing due to the involvement of foreign-based mining and explosives companies.

Jan 1, 1998

By Catherine Aimone-Martin, Mary-Alena Martell

Whole-structure and mid-wall responses of 33 non-traditional structures to surface coal mine blasting were characterized. Eighty-nine blasts were conducted at 11 mine sites throughout the U.S. to measure blastgenerated dynamic response of structures typically found in the proximity of surface coal mining. Structures selected for this study include log-type, manufactured (single- and double-wide trailers), “mine camp”-type, adobe, and stone. Traditional acoustic microphones, t&axial (ground) and single component (structure) velocity transducers were used to record airblast, ground motions, and structures response time histories with a common time base. Wall crack displacement gages were used to record static and dynamic movement of existing drywall cracks. The relative responses of selected “atypical” structures to blast vibrations and nonblasting causes of structural stress, including natural forces, environmental effects, and human habitation, are compared. The purpose of this study is to document and compare vibration characteristics of structures that were not included in previous studies conducted by the U.S. Bureau of Mines and others in establishing the widely adopted safe level blast vibration criteria in the U.S. An important objective of this study is to outline an evaluation process including structure uniqueness relative to cracking susceptibility.

Jan 1, 2002

By Rennie Kaunda, David Streeter, John Kemeny

This paper describes a field/laboratory study that was conducted in cooperation with a mine in Arizona. The primary purpose of the study was to investigate the effect of blasting energy on the crushability and grindability of the post-blast rock fragments. The crushability and grindability of the rock fragments were evaluated through laboratory comminution tests. A secondary purpose of the study was to investigate different laboratory methods for estimating the comminution properties of the rock fragments. In particular, a number of standard rock mechanics tests were conducted and compared with the comminution test results. Finally, the study was used to evaluate new technologies for estimating insitu rock mass strength and for assessing post-blast fragmentation. To estimate in-situ rock mass strength, the specific energy of drilling (SE) was calculated during blast hole drilling utilizing a continuous drill monitoring system. Post-blast fragmentation was estimated using the Split image processing system. Results from the study support the idea that increases in blast energy can enhance crushing and grinding. Also, several simple rock mechanics tests were found to correlate well with the results from standard comminution tests, which could prove to be useful in practice.

Jan 1, 2003