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By Joe Strobbe, Kevin Joe

The U.S. Bureau of Reclamation awarded PCL Civil Constructors the project to build a new visitor's center and parking lot structure at the Hoover Dam. The excavations for these structures present many blast design challenges. The visitor center, a 30 foot deep excavation was blasted in the Nevada side of the canyon wall, 600 feet above the existing power plant. This excavation also included a through-cut underneath the existing road that carries the traffic over the Dam between Nevada and Arizona.

Jan 1, 1993

By Kirk Yeager

All explosive formulations display some sensitivity to heat. A common technique utilized to measure an explosive’s response to thermal stimulation is differential scanning calorimetry (DSC). As DSC analysis is run on quantities of material easily handled in a laboratory setting, and is relatively inexpensive, it tends to be one of the more predominant tools utilized to determine potential thermal hazards of energetic materials. The analysis of energetic materials via DSC provides unique challenges, as both large energy outputs and significant production of gaseous products result from their decompositions. In addition, the unique thermal decomposition characteristics of ammonium nitrate (AN) based materials have also created difficulties in DSC analyses. A wide variety of techniques have been developed to study the decomposition of explosives. Traditionally, sealed glass capillaries were utilized to house samples. Recently, the introduction of specialty cells designed to withstand high pressures has enabled new sampling techniques to be developed. Analyses of explosives with both traditional and “high-pressure” cells will be compared and contrasted. Lessons learned about the application of both techniques towards analyzing thermal hazards such as incompatibilities will be presented. Inconsistencies in the results displayed during analyses of AN-based explosives will be highlighted. Recommendations on the best approach for analyzing the more problematic AN formulations will be given.

Jan 1, 2000

By Romel B. Villanueva

At the Yanacocha gold mine, in the Andes of northern Perú, the first instrumental tests were carried out in October 2019 to detect the initiation sequence of a production blast by detecting the EMF signal produced by the detonation from each blast hole in the sequence. Several experimental tests were carried out to choose the correct antenna and find the best setup of the high-speed Data Acquisition device (DAD) to detect these electromagnetic waves. Finally, the first measurement was obtained. With the instrument recording at a rate of 1 million samples per second, the initiation sequence was detected with 99.5% accuracy. It was found that it corresponded, without a doubt, to the designed scheme. The main result is that these tests provide us with a method and instrumentation to verify if the planned initiation sequence is carried out correctly in the field. In this way we can find operational deviations and detect possible misfires. This method has proven to be accurate, fast and easy to implement, mainly requiring an EMF signal capture equipment that can record at very high speed, something that is increasingly easier to satisfy with the development of microcontrollers. On the other hand, the type of antennas used in this method are low cost and very commercial. These tests have improved our understanding of the nature of detonation and have marked a new milestone in the development of blasting instrumentation in Peru.

Jan 21, 2025

By David Kennedy, Noel Hsu, Miguel Araos

The use of bulk explosive for mining applications started in the 50’s. Since then millions of tons of that material have been transported by road. However during that time, there have been several road incidents involving them. This type of incident has forced the explosives manufacturers as well as regulatory organizations to look for a better classification of explosives in order to regulate the industry as well as to mitigate community concerns over the classification of mixtures of substances that are regarded as precursors to explosives.

Jan 1, 2006

By Robert B. Hopler

The Hercudet ? Nonelectric Delay Blasting Cap System has undergone significant changes since the last paper on the subject was presented at the 1978 S.E.E. Conference. The changes have been made to improve reliability of the blasting machine at low temperatures, and to improve efficiency and economy in usage in surface mining. The paper includes examples of the blast design process, details of use of the new in-hole connected cap, and delay patterns which have found use in quarrying and coal stripping.

Jan 1, 1980

By J. -P. Tshibangu, E. Lefebvre

ABSTRACT : The Tournai’s region in Belgium is characterized by outcrops of limestone that were mined out long ago by different companies for cement and crushed materials. The region is densely populated and the vibrations generated by blasts in the quarries are of big concern. The occurrence of electronic detonators and development of computer sciences brought a new expectation in controlling the vibration level and, hence, carry out bigger blast operations. In this paper we present the results of two experimental blast programs that have been carried out by the Nobel explosive Belgium Company on the Gaurain-Ramecroix quarry to understand the effect of the delay on the vibrations generated in the neighborhood. The first program has been implemented during the early use of electronic caps in Belgium (1996) by performing some unit shots. An attempt to model the effect of the production blasts by the hybrid method (Hinzen 1988) gave promising but poor results compared to infield measurements. A new program (more than ten blasts) has been implemented in 2006 in which the delay and blast firing sequence (i.e. the order in firing adjacent holes in a row) have been changed; a new attempt is made to build unit signals by deconvolution and then try to model production ones. A comparison of the two approaches is made.

Jan 1, 2008

By Stephen Hamilton

This case history details the issues surrounding the rock drilling industry’s growing demand for straight holes, the importance of straight holes and the introduction of a new production drilling systems that can effectively and economically drill a true bore hole. Since the introduction of the hydraulic rock drill, the rock drilling industry has asked for a drilling system that would provide the fast penetration and low operating costs of Top Hammer drilling systems combined, with the directional control of Tube or DTH drilling techniques.

Jan 1, 1999

By D. Bartley, R. McClure, W. Reisz

Ever since the 8ms criterion was developed in the early 60’s there has been an ongoing debate among many blasters as to its actual value in controlling ground vibration. The perpetuation of the myth surrounding the 8ms window can be partly attributed to its simplicity and convenience as a means for regulatory compliance. Unfortunately, the mindset that many blasters have adopted has hindered the development and use of more effective techniques and in many cases can actually be counter productive to vibration control.

Jan 1, 2006

By Douglas Anderson

In the early 1980s, a method for controlling blast vibrations other than by modifying the Scaled Distance came into use. Research studies had indicated that blast vibration could be simulated by detonating a signature hole with the vibration monitored at critical locations, and then using a computer to superpose the waveforms with varying delays. By choosing delay times that create destructive interference at frequencies that are favored by the local geology, the “ringing” vibration that excites structural elements in houses and annoys neighbors could be reduced.

Jan 1, 2008

By W. De Graaf, C. Mkumbo

Bulyanhulu Gold Mine Limited (BGML) commissioned a project of sinking a Bulk Air Cooling Shaft during its programme to improve the ventilation system on the mine. As part of this project, a ventilation drift had to be developed and holed into the Main Shaft at 4920 Level. AEL Mining Services (AEL) were requested to provide a technical solution, which included monitoring of blast induced vibrations and to design drilling and timing plans to ensure blasting activities on the vent drift were conducted without disrupting the main shaft’s infrastructure.

Jan 1, 2011

By Larry R. Fletcher

The Bureau of Mines obtained blasting accident data from the Mine Safety ant Health Administration (MSHA), U. S. Department of Labor. These data were analyzed to determine the most frequent causes of accidents in mine blasting. Accident totals for 1971 through 1981 are tabulated for metal-nonmetal and coal mines both surface and underground. In the past 11 years (1971-1981, inclusive) there has been an annual average of 9 fatal and 121 nonfatal blasting accident victims. Underground mining averaged 6 fatal and 93 nonfatal injuries each year.

Jan 1, 1983

By Charles E. Joachim, Christo V. Lunderman, Charles R. Wdch

The U.S. Army Engineer Waterways Experiment Station (WES) recently conducted a series of precision-scale water shock experiments which consisted of the detonation of several 8-gram, 10-gram, and 12-gram spherical explosive charges. The charges were fabricated from NAX 2000 Primasheet explosive and were center-detonated. Commercial tourmaline crystal water shock sensors were used to measure the induced pressure fields in the water. The measured water shock waveforms and related parameters from the precision-scale experiments were in general agreement with data from larger-scale experiments.

Jan 1, 1998

By Sergio Segovia Parra, Victor Hernan Sheen Uriol

This contribution of the concept of mass blasting both closing and production allows breaking paradigms, to limit the number of tons to thunder. The areas of geotechnical different mining large mining companies worldwide and especially from the National Copper Corporation (CODELCO, Chile) has been declining volumes closing blasting and production, with the misconception to protect the end walls of the pit, before any geotechnical risks caused by various types of faults; especially the circular faults. A blasting of small tonnage can do more damage to a wall when it is not properly sequenced, leading to the coupling of the wave train and therefore the exponential damage in/s (peak particle velocity, PPV) on the wall of the Tagus. Blasting closing mass production and contribute technically and operationally in the dynamics of the following operations: loading, hauling, crushing, processing and preparation of the final product; eliminating delays to return to thunder small volumes where one must stop all mine equipment, incurring high costs and especially losing valuable time in the continuity of the following unit activities.

Jan 1, 2015

By Q Liu, P D. Katsabanis

The energy output of crushed AN/FO, crushed AN/FO mixed with Aluminum (5%, 6.4% and 9.4% A1 by mass) and a commercial emulsion explosive has been measured using a detonation calorimeter. The charges had a diameter of 10 mm and were heavily confined by a 11 mm thick copper shell. In order to achieve stable detonation glass microballoons were used in the explosives so that the density of the AN/FO charges would be around 1.1 g/cc. The charges were detonated in vacuum and the detonation products were analyzed using gas chromatography. It was found that energy values were very close to calculated values obtained by ideal detonation codes.

Jan 1, 1993

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 Michael S. Wieland

This report discusses the U.S. Bureau of Mines research regarding the desensitization and malfunction of cap-sensitive explosives deployed in underground coal mines. Delay blasting in underground coal generates severe shock waves and rifting forces that fracture and heave coal. These dynamic interactions can damage other charges still remaining in the delay pattern. The debilitating impacts precipitate degrees of reduced charge performance ranging from misfires to weak detonations or out-of-sequence firings. Damaged charges react poorly, perform less useful work, and/or generate atypical fumes with higher toxicity.

Jan 1, 1993

By Claude Cunningham

AEL has been developing electronic detonators continuously since 1986. It launched its first system for opencast mining in 1993, and now has two distinct product lines. The path has not been without great difficulty, but the determination to persevere was always buoyed by the strong encouragement of customers who experienced the transformed blasting results, as well as a clear vision of the enormous intrinsic value of the concept. The path of growth to dominant global supplier is traced through the separate application channels of coal stripping, quarrying, massive mining, opencast mining and narrow reef mining, to the first allelectronic detonator demolition blast in June 2001. Reasons for the slow coming to market of this highly desirable concept, which often coincide with reasons for the demise of various other systems, include the difficulty of safely mating electronics and explosives in a low cost environment; the extreme difficulties of achieving proper connection under mining conditions; the rapid rate of evolution of the technology, and the safety concerns raised by various accidents and incidents along the way. ED.s are now established as the way forward and are set to displace other systems in all serious applications. There is place for both programmable and pre-set delay systems.

Jan 1, 2002

By Stephan Iversan, Janae Singer

High resolution seismic refraction tomography has proved to be a useful tool to effectively estimate depth of blast induced damage in rock. Excavation blast damage can be as shallow as 1 to 2m (3 to 7ft) and requires resolution at a fraction of a meter for effective imaging. We used an accelerometer with flat frequency response to 1000Hz to record data at spacings of approximately 0.25 to 0.5m (0.8 to 1.6ft) along mine walls. The resulting tomograms of P-wave velocity show low velocity zones which we interpret as residual fracturing from blasting. Experiments on a concrete test block and at two underground mine locations give results that are consistent with fractured rock transitioning to competent rock.

Jan 1, 2009

By Sami Kara, Marsel Nabium

As a mining project is developed from conceptual to production phases, there exists a variety of uncertainties and difficulties that affect the operation’s designs and economic values. A notable design parameter to be taken into account is the factor of dilution. Dilution is the waste material not separated from the ore in the stages of mining and is sent to the processing plant. It is defined at the ratio of tonnage waste mined and sent for processing over the combined ore and waste tonnage milled. Dilution reduction is one of the areas that offer metal mines an opportunity to increase revenue and reduce costs, resulting in enhanced profits. Effective dilution control programs require interaction on a multidisciplinary level. This paper outlines recent initiatives undertaken at Polysmetal Silver Magadam Mine to reduce dilution and increase revenue. This paper provides an overview of the solution applied in underground Silver mine in Russia. The paper reviews the dilution problem throughout the entire mining process, and provides a rational approach to underground mine Blast design in order to minimize dilution. The mining companies put a lot of effort into extracting lower grade while minimizing cost. The dilution control assists with achieving this goal. In Polymetal Silver Magadam Mine we succeeded to control more than 20 blasts by keeping almost the same grade measured in the face. The results indicated that using the adequate blasting timing design can help to separate the ore from the adjacent waste in drift blasting with different ore body configuration.

The underwater explosions have been used for several decades for the determination of energy content of explosives. This test method is the only one by which shock, fly rock and total energy can be measured separately. It enables to develop the energy content of explosives for different purposes; the military high explosives should contain more shock energy whereas the fly rock energy is very important feature for the blasting explosives. The purpose of this study was to establish a test place for the underwater experiments in an old water filled open pit, to estimate the repeatability of the energy measurements, to calculate the standard deviations and to compare the total energy content of commercial explosives to the theoretical values calculated by the thermo dynamical program. The test method seems to work quite well especially for the homogeneous explosives. The difference between the energy content of theoretically calculated and measured values for the homogeneous emulsion explosives was about -3% and for the dynamite about -5%. The energy difference for the unhomogeneous ANFO was detected to be -19%. The diameter of the charge was 15 cm and it was obviously too small for ANFO to detonate ideally. On the basis of the test results this test method seems to fit best for the cap sensitive, completely homogeneous, spherical charges whose masses are big enough and which are initiated from the centre of the charge. The underwater explosions as a test method is the only one which can separate shock, bubble and total energies from each other and therefore makes it possible to develop the properties of explosives for different purposes which is very important feature of this method.

Jan 1, 2005