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By Robert Morgan

The mind-set that only blasters and their helpers need training in explosives can result in risk to other employees working at mine or construction sites where blasting is conducted. Misfires are not always immediately obvious during postblast examinations performed by the certified blaster in charge; the presence of undetonated explosives may not appear until well within the muckpile as was the case in the photo, right. To avoid accidents involving misfires, follow safety procedures specified in mine safety regulations, and the ISEE Blaster’s Handbook that include the following:

Jan 1, 2004

By Peter Moser

The average annual consumption of raw minerals in Europe is 10 ton per person. About 50 % is produced by blasting. For a population of 450 million (including the population from the countries of the new member states) this makes 2.25 billion tons of blasted rock, 80 % being building industry aggregates and industrial minerals. In aggregate quarries 10-15 % of the rock blasted can’t be sold, as the material is too fine, i.e. smaller than 4 mm. This ‘fines problem’ is worse in the quarries of limestone and cement producers where up to 30 % of the material is useless. Thus about 450 million tons of useless rock fines are produced and put on waste dumps every year, i.e. 1 ton/person. This problem is addressed by the research project LESS FINES - “Less Fines production in aggregate and industrial minerals industry” which is funded by the European Union under the project contract G1RD-CT-2000-00438. The project consortium, formed of nine partners from 5 EU countries, works on the following two main research subjects: 1. The determination of the natural breakage behavior (NBC) of the rock mass, which is defined as the particle size distribution curve for a certain rock mass with the maximum uniformity and thus for a given maximum particle size that fragmentation curve which gives the minimum amount of unusable fine material. The comparison between the NBC and an actual blast fragmentation curve allows to quantify the fines reduction potential. 2. The adaptation of explosives properties, charging techniques and timing in order to produce only the minimum, inherently unavoidable percentage of fines. With about 15 full time working persons the project is estimated to be one of the largest blast related research activities in Europe at the time of the project period. The project is coordinated by the Department of Mining Engineering& Mineral Economics of the University of Leoben.

Jan 1, 2004

By Richard J. Mainiero, Marcia L. Harris, James H. Rowland

In the past several years, there have been a number of blasting-related carbon monoxide migration incidents. In each case, there have been some common factors that appear to be related to carbon monoxide migration. Geology, heavy confinement of the blast, close proximity to the affected structure, and open pathways into the affected structure are just a few. Prince William County, VA is an area undergoing a boom in suburban development. In the year 2001, more than 4,050 new homes were constructed within the county.1 In the new housing development located in Bristow, VA, trench blasting was utilized to excavate proposed sewage and utility lines. On November 8, 2002, a trench blast was conducted for the installation of utility lines. Later that evening a carbon monoxide detector alarmed in a nearby house. The gas company and fire department sampled for carbon monoxide and measured 100 ppm and more than 200 ppm on the first floor and in the basement respectively. Subsequent efforts to prevent migration of CO into the nearby homes met with mixed results. The only reliable technique for protecting neighbors from CO appears to be the placement of CO monitors in the homes. The events are presented and discussed.

Jan 1, 2004

By Sam Kangwa, Thomson Sinkala

In the mining industry, drilling accuracy has a significant effect on the economy of operations. In this paper, results from the Nkana Division of the former Zambia Consolidated Copper Mines are presented. For the stope investigated, it was found that the extra operational costs alone were 462% of the planned costs! Clearly, there is more than good reason to pay attention to drilling of good quality holes.

Jan 1, 2004

By Fred Baldassare, Marcia Harris, Kenneth K. Eltschlager

Surface mine blasting was recently investigated as a potential source of high concentrations of stray gases found in nearby residences of western Pennsylvania. In one incident carbon monoxide was detected in a home and in the other, high concentrations of carbon dioxide were found in a home. Both carbon monoxide and carbon dioxide are by-products of blasting. However, other potential sources of these gases may also exist in a residential setting. In each case, gas chromatography (GC) and carbon isotopic analyses were used to define atmospheric concentrations inside the homes, and to determine the source of a stray gas. Molecular and isotopic analyses provide geochemical evidence as to the origin and source of the stray gas. This paper discusses elements of a stray gas investigation and the analyses necessary to identify the source of a stray gas.

Jan 1, 2004

Computational techniques in determining particle size distributions after blasting is getting wide acceptance. A well known approach to extract this kind of information from digital images is edge detection. The number of edge points on a given image increase proportional to the increase of the particles on the image. By selecting a conveniently smooth threshold, counting the signed edge pixels may be a suitable metric further used to quantify the number of particles in the image. Here we propose an image processing algorithm together with Adaptive Neuro Fuzzy Inference System (ANFIS) to efficiently count the rock particles with various sizes on a given surface. To determine a suitable approximation for a mapping between the number of edge pixels and the number of particles, ANFIS is a suitable tool. As a trainable classifier ANFIS proved itself as being better efficient approach than other well known multilayer perceptron classifiers. ANFIS is trained by using convenient training data pairs previously experienced from empirically counted sample images. When given a new image containing the particle information of selected surface, the hybrid neuro fuzzy image processing approach provides satisfying performance on counting the correct number of particles up to the given scale of sizes. In this paper an experimantal study for assessment of particle size using ANFIS is presented.

Jan 1, 2004

By Dale S. Preece, Vanessa S. Berg

Shaped charges are being utilized in defense applications against a wider variety of targets including concrete, rock, and soil. This work was motivated by a heightened interest in characterizing the effect of shaped charge attack on brittle, non-homogenous materials, in particular, concrete damage and penetration predictions resulting from a TOW-2a conical shaped charge (CSC). This paper presents a multi-stage approach for accurately predicting the high explosive detonation and subsequent jet formation due to the collapse of shaped charge liner, the changes in jet length and diameter as a function of standoff distance, and the jet-target impact dynamics. The first part of the analysis approach employs the commercial 3-D Eulerian-Lagrangian hydro-code AUTODYN to predict the shaped charge jet formation. 2-D finite difference Eulerian subgrids represent the explosive and casings components, while thin components like the liner are modeled with Shell subgrids. The Pugh, Eichelberger & Rostoker (PER) jetting theory option is invoked to obtain the jet and slug masses and associated velocities. The jetting data is post processed where the jet velocity gradient and jet mass is used to solve for the new jet length and diameter gradient at a desired standoff. The final computation involves a 2-D fully Lagrangian model in which the jet and velocity gradient is represented by a string of Lagrangian segments and the concrete target is defined as Lagrangian with the newly developed RHT (Riedel, Hiermaier, Thoma) constitutive model. This model has a third invariant dependency that accounts for failure mechanisms in brittle materials.

Jan 1, 2004

By Winfried Rosenstock

AEBT has been available for a couple of years and is successfully applied in Australia. Up to now it was mainly used in coal surface mining at the Australian East- Coast. Presently, the proved results reach ~ 50 % reduction of Drilling & Blasting costs and a productivity increase of between 10 and 20 %. In 2003 it was for the first time used in surface metal-mining. The mine features for the time being an extremely difficult geological environment and had above to be carried out in the transition level waste/ore. Reductions of wall control, powder factor and vibrations were the main target.

Jan 1, 2004

I was lucky to land a job in the powder business. I was looking for some way to support my wife and first child to be when I saw an ad in the Hercules magazine, “Explosives Engineer” for technical representatives. I answered the ad in hopes that a geologist might find something else to do besides sit oil wells or “doodlebug” for oil. Both of these occupations I had tried and while the money was good the life was a bit erratic. The Army also wasn’t made for a guy who asked too many questions although my two plus years in uniform were interesting and in a few cases fun.

Jan 1, 2004

By Frank Sames, Brad Terhune

In many construction projects and in most quarrying operations drilling and blasting remains the only feasible method of loosening rock in the removal of rock or overburden, the development of the quarry and in the production process of crushed stone. Often, a blasting plan is required for the project or the quarry’s permit with primary concerns over safety and site security, and compliance with environmental regulations or standards. From this plan, a blasting program has to be developed considering the varying requirements of production, the advance of the mineral extraction and the environmental impact. The actual blast design requires a planning and optimization process. This optimization process is driven by the blasting technicians/engineers, project or mine management and often by community concerns. The blast design process comprises the selection of blast parameters, including the explosives, and the actual layout of the blast. Design tools and controls range from conventional methods based on established blasting practices to advanced design tools or computer models. Blast monitoring and evaluation can also range from empirical to advanced blast assessment. The data and information from each blast or a series of blasts can further be used in the optimization process. Its success depends upon recording the data, the timely transformation of the data to relevant information, and the development of process oriented knowledge. The elements of the blast design process are summarized and described with examples of state-of-the art engineering controls. The reporting and monitoring of individual blasts is discussed with respect to data management and information systems. A conceptual overview of the components and interfaces of a blasting program is given and discussed on the background of technical, management and community concerns.

Jan 1, 2004

By Jesus Pascual, Benjamin Cebrian

A new Convention Center is going to be built in the millenary city of Toledo, right in the old city limits. The workings will need to excavate some 80.000 cubic meters of granite, which has, a trench-like structure already blasted for the construction (60 years ago) of a parking lot and a shopping area. Surrounding this trench, some few feet away, there are structures and buildings from the 16th century and remainings from previous times that need to be preserved from any damage caused by blasting. Because of this, a vibration analysis was designed according to the special characteristics of this work. Structures to monitor were located at several levels. It considered three different directions of study in order to evaluate the impact of vibrations of the structures located at three different heights of the granite trench. On top, the historical convent of Santa Fe, with some remaining from the 8th century (Muslim domination of the Iberian Peninsula), on the bottom, the Justice Hall of Toledo with 16th century walls, and, in the middle, a wall and a tower from times of the king Phillip II (16th century, the time of the Spanish Empire).

Jan 1, 2004

By Satish Kate

Mining of Iron Ore in India is done by Surface Mining methods and most of the deposits are massive and are occurring in Hills, surrounded by green forest cover. While majority of iron ore produced are from mechanized mining systems, some quantities are also produced from semimechanised mines. In mechanized mines, apart from state-of-the-art level of mechanization, the Run-off-Mine ore is subjected to multi-stage crushing, screening and washing/beneficiation, for improving the grade and ensure segregating of different size range. The steel plants within the country have been operating their own captive mines, where both lumps and fines are used in their furnaces. In case of mines, which exclusively supply ores to export market, the lumps produced yield very high price and thus efforts are being made to maximize lumps recovery. The mine, where the author had been associated, is an export-oriented mine which supplies iron-ore to Japanese steel plants.

Jan 1, 2004

By P. R. Mohanty, Kaushik Dey

Blast-induced tunnel overbreak prediction in the past has been based on peak particle velocity measured far from the blast site with necessary extrapolation. This has often resulted in suggesting higher damage threshold levels of Acceleration/PPV for overbreak prediction (Bogdanhoff, 1995, Holmberg and Persson, 1997, Murthy and Dey, 2002). These, site-specific far-field blast vibration studies, have also revealed that predicted PPV levels for overbreak could lie in the range of 700-5000 mm/s, an extremely wide range to generalize. Experimental blasts were conducted, in an underground metal mine located in eastern India, with an objective to study the level of acceleration /peak particle velocity generated in tunnel blasting. Accelerometers and tri-axial geophones with measuring ranges upto 500 g, 254 mm/s respectively, were mounted on the tunnel floor close to the blast face, with sensor distances varying from 15.25m to 36.10m. Due to straight faces the measuring distance could not be reduced further anticipating, in particular, cable damage. The equipment used was of M/s Instantel Inc., Canada. The blast pattern used was burn cut with large dia relief holes providing the required free face. The blast hole depth was 1.8m. Tunnel overbreak was measured using a telescopic offset rod fabricated at Indian School of Mines, Dhanbad, India.

Jan 1, 2004

By Peter Reinders, Dirk Hummel

This paper describes a new digital Centralized Blasting System (CBS), which is currently being introduced into underground applications. The CBS makes use of the field-proven detonator and equipment technology of an electronic detonator system and existing mine radio communication networks. Therefore no capital investment for additional mine infrastructure networks is required for the deployment of the digital CBS. Components of the new system are a Remote Blasting Box for use at the actual blast site and a Master control unit ‘Lockbox’ which is located at the central blasting location of the mine. The system is operated via a PC based centralized blasting software. Several sophisticated safety devices guarantee the highest safety standards are maintained with the application of the new digital CBS.

Jan 1, 2004

By Bob Turnbull

The dictionary definition of calibration is: to determine by measurement or comparison with a standard, the corre c t value for each scale reading on a device.1 As a consultant or blast contractor, you assess risk every day. But, have you considered the importance of, and the risks associated with the calibration of your seismograph and the accuracy that is p rovided? Can your calibration pro v i d e r back you up in times of trouble and provide documented evidence that the equipment was functioning within specification? Can their calibration pro c e d u res withstand independent scrutiny and be shown to be traceable to a National Standards for accuracy of measurement? These are important documents that in court provide tremendous support that blasting and monitoring activities are conducted professionally and competently.

Jan 1, 2004

By Ann Barron, Mark Abernethy

Along with the immense benefit of modern explosives seismic and acoustic effects caused by their detonation can be disruptive and alarming to many people. Claims range from affecting sexual performance to outright demolition of a residential structure. Regardless of the quality of the blast design and other precautionary measures, the inherent danger posed by the use of explosives often leaves residents searching for restitution. Consequently, many blasting companies today find themselves at the center of litigation. In the event that a blasting complaint proceeds to litigation your case will not be decided on “reasonable doubt” as in criminal trials. Instead, the jury will be instructed to decide guilt or innocence on a “preponderance of the evidence” presented. Even if you are able to present the best and most complete evidence that you have not caused the claim, the jury may rule in the favor

Jan 1, 2004

By William McFerren, Pragasen Moodley

In contrast to global trends, African, especially South African, surface mining operations have shown a significant rate of adoption of Electronic Detonators (ED’s) over the last few years. Proven benefits of converting to ED’s from pyrotechnic initiation systems have aided this market conversion. These benefits are experienced throughout the mining operation. Benchmarking exercises, prior to the introduction of ED’s, form part of the conversion process and allow for quantifying improvements. Extensive work has been done on quantifying the benefits of converting to ED’s and have shown that results can be reproducible. Improvements have been experienced in many applications and include environmental impact control, improved mining efficiencies, increased cast benefit and improved size distribution. These step changes in blasting results, in conjunction with the adoption of ED technology have aided the rapid conversion of the African surface market.

Jan 1, 2004

By H. R. Maggard, C. M. Bollinger

Solving the problem of detecting underwater explosions from "dynamite fishing" can be done by using a system of sonobuoys programmed to detect the acoustic waves from underwater explosions. The system includes three anchored sonobuoys, which have radio communication to a central station. Each sonobuoy will detect the direction the blast occurred, and then send the magnitude of the acoustic waves and the blast direction to the central station where the blast distance will be calculated. The central station can the send the coordinates to the authorities who can find the location using GPS systems onboard their boats.

Jan 1, 2004

By E. Contestabile, B. von Rosen

Recently, the Canadian Explosives Research Laboratory (CERL) completed its investigation of a truck accident, which involved 18,000 kg of commercial explosives, 13,000 kg of which was ANFO. Over the three years of the investigation unconfined burns of piles of ANFO were performed. In its final phase of the investigation, two burn trials were performed in an attempt to recreate the accident and the ensuing fire, to identify probable mechanisms that led from burning to detonation. Two full-scale tests were performed using complete tractor-trailers. In each test, the trucks were placed in a jack-knifed position with the majority of the explosives located on the ground in front of the trailer. The explosives were placed in a manner to provide maximum confinement and to maximize the possibility of explosion/detonation while remaining as faithful as possible to the perceived accident geometry. The tests were instrumented using thermocouples and video cameras and observations were made on the burning characteristics of the explosives, tractor-trailer and tractor-trailer components. In each test the explosives burned calmly for approximately 80 minutes. There was no evidence of explosion or of unstable burning. The heat caused several truck components to rupture violently. These included the tires, some engine components, the spring brake chambers and possibly the fuel tanks. Of these, the most violent were the truck tires. Although no quantitative data was gathered on rupture violence or fragment velocity, it is speculated that several truck components might produce fragments with sufficient energy to initiate heat-sensitised explosives under favourable circumstances.

Jan 1, 2004

By Dale Preece, Vanessa Berg

This paper presents a two-pronged vulnerability analysis approach for treating minimally reinforced concrete (RC) structures subjected to explosive events. This work was motivated by a heightened interest in homeland protection involving both malevolent and accidental explosions and the need for assessment of critical facilities subjected to an explosive detonation. The first part of the analysis approach employs the commercial 3-D Eulerian-Lagrangian hydro-code AUTODYN, while the second part of the analysis employs Single-Degree-of-Freedom (SDOF) methods, each predicting the dynamic response of the minimally RC walls, slabs and columns to explosive loading. The concrete is treated with the newly developed RHT (Riedel, Hiermaier, Thoma) constitutive model, which accounts for failure mechanisms in brittle materials. Predictions from AUTODYN are verified using the equivalent SDOF reinforced concrete code, SPAn32, developed by the US Army Corp of Engineers and agreement between the results indicates a high level of accuracy in both methods of analysis, allowing for accurate predications of airblast-structure interactions and failure mechanisms.

Jan 1, 2004