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By James Stuart

A man died when the primed charge he was holding against his chest exploded. He was doing legitimate explosive work, and he was following all the safety procedures he had been taught. He and his colleagues had done this, thousands of times previously, with no ill effects.

Jan 1, 2007

By Otto E. Jr Crenwelge, Timothy A. Peterson

We have developed a site-specific method for analysis, prediction, and control of ground vibrations induced by overburden blasting operations in surface coal mines. Field tests conducted at R&F Coal Company have verified our approach for obtaining signatures of the overburden vibration characteristics at locations of interest near the mine, selecting the optimum excitation frequency for minimizing vibrations, measuring and synthesizing multiple-charge excitation signals for minimizing vibration amplitude and duration and controlling frequency, accurately predicting the multiple-charge vibration response in both the time and frequency domains, and accurately controlling the blast detonation to achieve the predicted vibration control. Initial field studies also indicate that by minimizing the vibrational energy radiated from the blast zone, and by optimizing the number of charges detonated per delay period as allowed by this technique, more effective use of the explosive energy is obtained within the blast zone itself for improving overburden fragmentation, swell, and cast. In all of the phases of this technique, including actual blast detonation, personal computer hardware and software have been verified for use in either field or office environments.

Jan 1, 1986

By John Arrell, James Stuart

We have developed a tester that is uniquely able to measure the no-fire power level of certain types of electro explosive devices (EEDs). In the past, it has been difficult to establish a no-fire power level for nonlinear conductors, such as semiconductor-bridge (SCB) EEDs, and conductive-mix EEDs.

Jan 1, 2011

By Kunihisa Katsuyama, Yuji Ogata, Yuji Wada

Test blasting was carried out to study the flying characteristics of rock mass caused in bench blasting. The quantity of explosives was increased from 7.6kg to 9.1kg and the Minimum burden was changed from 131mm to 451mm. The effect of condition for the characteristics of fly rock were considered. The fly rock was observed using the high-speed camera and video to study the flying characteristics of the rock mass caused in the bench blasting. Numerical simulation of fly rock was carried out using DDA (Discontinuous Deformation Analysis) method. It was clear that the DDA method can be applied in the simulation of fly rock caused in bench blasting.

Jan 1, 1997

By Lyall Workman, P D. Katsabanis

Energy released by the explosive is typically partitioned in brisance, heave and losses. The fact that energy released in the P-V expansion curve below a certain point is lost has resulted in the concept of available energy. Through simple calculations it is shown that energy released at pressure levels thought to be low, amounts to a significant proportion of the total energy value. Furthermore, throw calculations indicate that the assumed loss of that part of energy does not justify practical results. Loss of energy at the low pressure levels may also not be justified from the fragmentation point of view as pressure levels below 1 kbar are enough to extend radial fractures around a borehole. Finally the equation used for the P-V behaviour of the explosive gases is important in throw calculations. Simplified approaches may not reproduce the performance of the explosive which is not characterized only by its energy content.

Jan 1, 1998

By A. Ribeiro

The effective utilization of resources and process optimization play a crucial role in the sustaining and growth of overall businesses. This principle holds true in the mining sector, where particular attention is required during the comminution steps. This necessity arises from the fact that mining operations often consume substantial amounts of energy in mineral processing. Therefore, it becomes imperative to thoroughly study the integration of comminution steps. In many instances, an approach to be studied is the operation commencing with the drill and blast phase and culminating in the grinding product process. Nevertheless, establishing an optimal integration between drill and blast operations and the grinding phase is a complex undertaking due to the direct influence of rock characteristics on this process. And in many cases, the complexity and variability of such physical characteristics makes mining operations to ignore such influence. Consequently, Enaex Mining Technical Solutions (EMTS), in collaboration with Lundin Mining's Chapada Mine engineering team, and with the assistance of Hatch Consulting and Technology, has undertaken a comprehensive study aimed at enhancing mill throughput at the Chapada operation. The basis of this study lies in characterizing the rock masses present in the Chapada Mine to gain a deep understanding of the material that needs to be comminuted. Subsequently, the mineral processing team determined the most suitable size distribution for the Run-of-Mine (ROM) material. With this information, the drilling and blasting team built a site-specific blast fragmentation model, able to simulate various blast design scenarios. This approach enabled to optimize the utilization of available drilling and blasting resources while striving to achieve the optimum ROM characteristics. Since 2021, the Mine to Mill methodology has been progressively implemented at the Chapada Mine. As a result, the blasting engineering team now utilizes the blast plans generated by the fragmentation model simulations as a foundation for designing blast plans that align with the operational and financial capacities of the mine. Overall, it was predicted that this implementation could lead to an average increase in mill throughput of 13-22 % depending on blend feed, once all recommendations are implemented. Even with partial implementation, plant results demonstrate a 5 % increase compared to the period before the Mineto-Mill project, without any coarsening of the associated grinding product size.

Jan 1, 2024

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

By María Virginia Ramírez, Alejandro Alarcón, Alea Reyes

Reactive grounds (presence of FeS2, CuFeS2) can create hazards in a mine; misfires to premature deflagration or detonation of loaded blast holes. This occurs because some minerals can react to ANFObased explosives. Due to a high potential event that occurred in The Mine in 2013, The Mine and the Explosive Provider (“The Company”) are conducting a soil characterization of the areas containing reactive sulfides. This study was planned along with The Mine and it is being developed by a multidisciplinary team.

Jan 1, 2018

By Jhon Silva

"Signature Hole and Waveform Superposition techniques used to predict and control mine blast ground vibrations require a clearly defined information collection configuration. The collection of this information determines the scope and success of the ground vibration prediction. Application of the Improved Signature Hole technique using the Silva-Lusk equation requires the collection of at least two informational elements from any specific production shot. The first required element is a signature waveform, and the second element is the overall production blast waveform. The signature waveform depends on detonated charge variables such as the amount of explosive in use, use of decking, the possible detonation of several holes at the same delay, and many others. The production blast waveform is beneficial to the Improved Signature Hole methodology when used to calibrate the model, and toobtain accurate vibration predictions for different timing configurations."

Jan 1, 2017

By William Adamson

Precise and data driven methods of predicting and modelling blast induced vibration intensity are created and applied under field conditions on a routine basis today. These models are fed with controlled field measurements of vibration pulses generated by controlled charges under known geometric conditions. With such models blasting and geomechanical engineers can estimate vibration intensity at established critical points in mine bench geometry (surface mining) as well as within semi-permanent crown and rib pillars (in underground mining).Damage to bench walls and destabilization of large-scale geomechanical structures can be partially attributed to high intensity blast induced stresses on the rock mass and structures that define important features such as safety catch berms and haul roads. In the underground environment, weakening of critical pillars in block caving or Long Hole Open Stoping(LHOS) operations may lead to ore sterilisation. Blast vibration intensity can be linked with physical alteration in critical rock mass volumes within themine. Often the potential for vibration damage is estimated by the calculation of a critical value of vibration intensity, derived from a consideration of laboratory measured rock matrix properties. Efforts to confirm the accuracy of these estimates of critical vibration level include post blast excavation photography as well as the visual examination of rock mass, pre-and post-blast, using video camera observation of the walls of purpose drilled observation holes. These methods clearly indicate a change in fracture state due to the blast induced vibration, however further modelling of geomechanical stability will benefit if seismic measurement data can be interpreted in terms of geomechanically relevant strength parameters. This paper describes some of the results of previously unpublished research studies conducted in underground operations in Chile and Australia, where cross-hole seismic measurement profiles were interpreted in terms of dynamic modulus. This work dates from a period between 1987 and 1990 and the Author suggests that 30 years on, applying modern day technology, instrumentation and modelling methods, more meaningful, practical and applicable results may be obtained.

By D P. Proudfoot, S G. Keith, D P. Onagi

A number of aspects of the Canadian concept for nuclear fuel waste disposal are being assessed by Atomic Energy of Canada Limited (AECL) in a series of experiments at its Underground Research Laboratory (URL) near Lac du Bonnet, Manitoba, Canada. One of the major objectives of the work being carried out at the URL is to develop and evaluate the methods and technology to ensure safe, permanent disposal of Canada's nuclear fuel waste.

Jan 1, 1996

By Serge V. Krasvin

The excavation of large amounts of ferrous and non ferrous metals, coal, shale, and other minerals - requires intensification of blasting techniques. In the late 80s in the USSR, the annual consumption of explosives reached more than 2.7 ml t., the great bulk of which consisted of granulated and powdery explosives. Nevertheless, slurry explosives, due to lower costs and better blasting characteristics, are gaining a stronger position in the explosives market.

Jan 1, 1992

By Paul Worsey, Richard P. Ayres, Mark F. C. Schmidt

A new alternative technique designed to reduce rock scatter and flyrock during boulder blasting is being developed at UMR. The method uses small explosive charges and is designed for shooting in close proximity, while utilizing common blasting products found on the operators’ site. This ongoing work is being conducted internally as graduate and undergraduate level research. A paper describing the general technique was published in last year’s proceedings. This particular portion of the work was performed as an undergraduate research project as part of the requirements for the explosives emphasis degree option at UMR. Previous model work was performed using cubes of concrete. However, in real life boulders are often flat and irregular rather than perfect cubes. The purpose of this work was to determine how to deal with flatter boulders. The work comprised using different geometry blocks (simulated boulders) of the same volume (1 cubic ft.). Square concrete boulders using an 8.5bag concrete mix were cast using different width to height ratios (varying from 1: 1 to 3.7:1). Single 5/8 inch holes were drilled to 2/3 the depth of the blocks, charges placed approximately l/2 way in to the holes and the holes filled with water. The explosive charges comprised ICI Masterdets containing a OSg High Explosive base charge and incremental added weights of C4 explosive. In the experiments, the block height was progressively reduced and to compensate the charge weight was increased until acceptable fragmentation was achieved. It was found that a significant increase in charge wt is required to achieve the same fragmentation as the width to height ratio increases (the boulder becomes flatter). Furthermore, the increase in charge weight required is proportional to the width to height ratio. Basically, you have to use a higher powder factor for flatter boulders.

Jan 1, 2000

By William R. Adamson

This paper describes some of the results of previously unpublished research studies conducted in underground operations in Chile and Australia, where cross-hole seismic measurement profiles were interpreted in terms of dynamic modulus. This work dates from a period between 1987 and 1990 and the Author suggests that 30 years on, applying modern day technology, instrumentation and modelling methods, more meaningful, practical and applicable results may be obtained.

Feb 1, 2020

By Wendell W. Harris, Stanley J. Vitton

In the United States each year it has been estimated that expansive soils cause approximately $9.0 billion in damage to buildings, roads, airports, and other facilities. This figure alone exceeds the damage estimate for earthquakes, floods, tornadoes, and hurricanes combined. Unfortunately, some cases of expansive soil damage (swelling) are blamed on rock blasting operations if the blasting operations are located within the immediate area. While simple tests, such as the Atterberg limits test, can characterize a soil as expansive, it does not necessarily answer the question whether the foundation soils are causing distresses to a structure. In particular, it appears that once a soil has been labeled as nonexpansive it is no longer considered as a problem soil, in which case blast vibrations become the prime suspect.

Jan 1, 1996

By C. Pelley, S. Kelebek, G. Kunzel, P. Katsabanis

Small blocks of granodiorite have been subjected to blast loads from a single borehole and from a series of boreholes detonating at various timing intervals. The damage of the blocks was assessed through P-wave velocity monitoring, measuring the change of the point load strength index of the rock after dividing the large blocks into smaller ones and measuring the work index of the material at different distances away from the blasthole. Numerical modelling with the AutodynTM code enabled visualization of damage. It was shown that damage is optimum at a small delay time between successive holes while it drops rather drastically after this point.

Jan 1, 2003

Dear All, I am looking for information about vibrations and effects on fish in pools. A tunnel blast is planned to be carried out as close as 300 meters to a freshwater fish growing plant. What is the vibration criteria for fishes in pools? Your comments will be highly appreciated.

Jan 1, 2012

By John Cory, David Lily, Bill Hissem

The Lafarge granite quarry in Cumming, Georgia is using Principal Component Analysis (PCA) and Biplot charting to identify important variables and control air blast and vibration. Every blasting situation is unique and PCA and Biplot charting help to clarify the major variables determining air blast and vibration.

Jan 1, 2010

By Jikai Rong Changai Liu

The dig instrument by blasting is a,new product we developed(See Fig. 1) It is an apparatus to dig hole at the ground. It is composed of combustor A, combustor B, charge pipe and shock head. Work characteristics of Combustor A are that combustion time is 1. 5 seconds, driving force is 725kg. Work characteristics of combustor B are that the combustion time is 1. 3 seconds, driving force is 460kg. After the combustor is ignited, the charge pipe is drived into ground immediately. Then, whole dig instrument is threw out automatically, but explosive in charge pipe is left in ground and blast in the twinkling. The diameter of vertical hole formed by blasting is 3cm to 60cm which is controlled according to engineering requirement. The maximum depth of the hole diged by using the dig instrument is 2M. It applies to blindage of single solidier in military affairs, and hole planting pole as well as sewer in civil use and so on. The two shots are charged in combustors to dig a hole. The maximum weight of shot is 490g, minimum is 130g. The whole process diging hole is completed automatically in about ten seconds.

Jan 1, 1998

By T. Palangio

Most blasters wouldn’t think of initiating a shot without a seismograph to record vibration and air blast results. Some might even measure the velocity of detonation but few surprisingly record the event on video, photo document loading conditions or take pictures before and after the shot. This paper discusses digital imaging, the equipment, methods, techniques and information that can be learned from digital pictures taken in the field during blasting operations. The guy who said “a picture is worth a thousand words” probably understated it.

Jan 1, 2008