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By Bengt Ljung

Manual charging of long upward drilled holes in mines is a heavy and risky job today. Mechanization of this work has been requested for some time by miners, their supervisors, industrial safety organizations and the trade unions, all of whom are interested in improving the working environment. This paper presents newly-developed charging systems intended primarily for charging in connection with sublevel caving and sloping. These systems have been field-tested during 1977 in the LKAB mines in northern Sweden. The results of these field tests and the results of laboratory work conducted to help eliminate the risks involved in charging explosives are also discussed. The equipment being tested (see fig. 1 and 2) consists of a charging vehicle with articulated steering, the PT-60, which has been equipped with a hose feed system mounted on the hydraulic extension boom. From a sheltered position, the operator brings the detonator and primer to the hole opening, after which the hose is pushed in mechanically to the end of the hole. Measuring equipment indicates when and if the end of the blasthole is reached. The operator then withdraws the hose mechanically as charging takes place.

Jan 1, 1978

By Robert Hopler

The 1800’s were a time of tremendous advancements in science and experimentation, and earthquakes were a subject of great interest. The meetings of the British Association for the Advancement of Science in 1853 and 1854 are good examples of this. The proceedings of the Association for the 1854 meeting includes a table entitled “Catalogue of Recorded Earthquakes from 1784 to 1850” which takes up 326 pages, and lists available information on approximately 3000 earthquakes. The 1853 proceedings have a similar table for earthquakes recorded from 1606 B.C. to 1783. In the 1854 volume there is a “Report of the Committee on Earthquakes,” which provides us with a view of the general state of the science. Excerpts from that report follow:

Jan 1, 2006

By David Lilly, Robert Ethier, David Bremer

The Lafarge Ravena Cement Plant in Ravena, New York demonstrated continuous and extraordinary improvement in productivity during the past several years. The factors driving continuous improvement at the Lafarge Ravena Plant include: 1) Management techniques including regular scheduled and effective Blasting Optimization Team meetings. 2) A real time blasting database to guide blasting product and procedure decisions. Key decisions involved all levels of quarry and blasting supplier personnel and a close working relationship between production and blasting areas of expertise was demonstrated. 3) Blast optimization and optimization of quarry operating parameters such as blast location relative to crusher location, hours worked, etc.

Jan 1, 2007

By Mark S. Stagg, Rolfe E. Otterness, Stephen A. Rholl

The Bureau of Mines has developed computer software to study the effects of initiator scatter on all aspects of the blasting process. The software is useful because it is difficult to obtain actual initiator data, particularly the standard deviation which is needed to express initiator scatter. The new software is structured to allow blasters to answer the question: how precise must initiators be to insure a successful blast? Successful is defined statistically in terms of a confidence level. The software can be used with any possible design since there are no restrictions due to size or complexity.

Jan 1, 1992

By Mike Wheat, Catherine Aimone-Martin, Brandon Pease

The Kneeling Nun rock pinnacle is a prominent landmark, 90 ft in height and 35 ft in width, that resides on a bluff overlooking the Santa Rita pit at the Chino Mines Co. operations near Silver City, New Mexico. The company plans to expand the current pit limits, resulting in a change in direction and distance of hard rock mine blasting operations in relation to the pinnacle. Concerns about the stability of the pinnacle adjacent to mining activity has prompted company personnel to enhance the seismic monitoring program both on the pinnacle and along the current open pit highwall that forms the base support below the pinnacle foundation. This paper presents the vibration response characteristics of the pinnacle, in terms of amplitude and natural frequencies of motions and damping characteristics, for measurements recorded at the top and base of the pinnacle. The influence that blasthole initiation timing and sequence of hole detonations have on vibration response is discussed. A simple analysis is made to estimate factors of safety against cracking of the landmark as well as blast-induced slope instabilities within the foundation rock.

Jan 1, 2000

By Thomas P. Dowling

Since the 1950's, blasting practices have undergone many revolutionary changes. Some of the more radical departures have involved, in addition to high speed drilling equipment, a myriad of new explosives, blasting agents, boosters, initiators, initiating systems and delay devices. The introduction of ANFO in the mid 1950's as a blasting agent seems to have instigated a trend toward the development and use of less sensitive blasting agents. The evolution of slurries or water gels has produced dense, high strength, water resistant products which has further promoted this trend away from the more sensitive, conventional explosives.

Jan 1, 1975

By Braden Lusk, Kyle Perry

Recent events and MSHA actions have resulted in discussion and reevaluation of the practice of sealing abandoned coal mine workings. In the past, MSHA has approved alternative seals based on a pass/fail system that required minimal engineering. Disasters involving fatalities led MSHA to impose higher seal pressure requirements based on research and experiments. Impending new MSHA seal regulations will force manufacturers and industry to obtain a high level of engineering expertise. The expertise necessary is in the field of blast resistant design, which is not easily accessible due to the limited number of experienced individuals within the mining industry.

Jan 1, 2008

By Lewis L. Oriard

The purpose of this paper is to provide an overview of close-in blasting effects on various types of structures and building materials, as encountered in this writer's professional practice. Structures range from old, deteriorated historical monuments to new, heavily reinforced buildings. Materials range from clay adobe to concrete and steel. Site locations range from tropical to arctic. Blasting ranges from sculpture blasting inside buildings to "coyote" blasting and large surface blasting operations. Space limitations permit a brief discussion of only 25-30 specific cases, but they have been selected to be typical of conditions found on hundreds of similar cases. The writer was asked to present a discussion of representative cases where relatively high vibration intensities were experienced. Virtually all of these cases were free of damage, but the few damage cases provide valuable insight to the mechanisms involved. Observations of such damage and non-damage cases have served as the basis of this writer's criteria for various structures and materials, as well as the technology to conduct blasting operations within those criteria. A sampling of these experiences is gladly shared with the reader.

Jan 1, 1991

By Dennis G. Wright

The Minister of Fisheries and Oceans for Canada is responsible, under the Fisheries Act, for the protection of all marine organisms and their habitats. The detonation of explosives in or adjacent to fish habitat has been demonstrated to cause disturbance, injury and/or death to aquatic organisms, and/or disturbance, destruction or alteration of their habitats. The Department of Fisheries and Oceans recognizes that the use of explosives may be the most practical or cost effective method by which to complete a project and has undertaken the development of a set of guidelines that will prevent or minimize the destruction of or disturbance to aquatic organisms and their habitats while at the same time allowing scientific and industrial users of explosives to proceed with their projects.

Jan 1, 1997

By Cristian Rodriquez, Fernando Fernandez, Rodrigo Fuentealba, Tom BoBo, Maria Rocha, John Kemeny

This paper describes a case study that was conducted at a new mine in South America. This mine has significant geologic variations that will result in different distributions of hard and soft ore being mined at different periods of time over the mine life. A study was conducted to determine the optimum blast design that will meet the mill throughput requirement of 95,000 tonnes (104,720 tons) per day for the first 10 years of the mine life. As part of this study, field rock mass characterization and laboratory tests were conducted. This includes standard rock mechanics tests as well as rock breakage tests used in mill simulations. The geology of the ore body was broken up into four Geologic Units, and statistical variations in the properties were determined for each unit. Using this data along with the data on the occurrence of the different geologic units over time, simulations were made of the run-of-mine (ROM) fragmentation due to different blast designs, and these results were used in simulating the resulting throughput after crushing and grinding. Four blast designs were considered with powder factors of 0.44, 0.54, 0.64 and 0.94 kg/t. The results of this study show that determining the proper blast design is important in ensuring that the mill throughput requirement will be met over the mine life.

Jan 1, 2015

By Gregory Lorsbach, Wade Hutchison, Earnest Grigoryan

Comparing measurements from multiple seismographs, particularly when the instruments are deployed in a “side-by-side” situation, is often problematic. Measurements often differ by as much as a factor of two. These differences are attributed to issues related to calibration, geophone coupling, and differences in geology over very short distances. Unfortunately, these explanations are often purely qualitative, but are accepted as factual. Shake table testing often demonstrates that those seismographs that indicate large differences for a particular vibration event, may correlate within a few percent of each other and the known shake table input. Geophone coupling also does not fully explain the difference in measurements since geophones in side-by-side measurements are deployed identically. Differences in geology do not explain the difference in measurements since it would be unrealistic to expect significant differences in distances less than one meter in a normal monitoring situation. Utilizing a new technological approach to vibration measurement and analyzing numerous side-by-side measurements, it has become clear that a significant portion of the observed differences between seismograph measurements are instrumentation induced. This study examines and describes some of the most significant sources of the seismograph error budget.

Jan 1, 2005

By Martin Langenderfer, Sergii Chertopalov, Catherine Johnson, Vadym Mochalin, William Fahrenholtz

The high temperature and high pressure of an explosive detonation can be used for the production of nanomaterials. The controlled detonation of explosive compositions along with the collection and characterization of reaction products encompasses a process known as detonation synthesis. The primary advantage of the method of detonation synthesis is the possibility for producing monocrystalline nanoparticles with diameters of less than 10 nm. In order to successfully synthesize nanomaterials via the detonation process, it is necessary that the explosive detonation is conducted in a sealed environment. This environment when pulled to a vacuum or purged with inert gas such as argon will reduce the oxidation of detonation reaction products. Detonation synthesis testing is currently being conducted in a 1.8 cubic meters (m3) (64.3 cubic feet (ft3)) ellipsoidal pressure vessel consisting of two interlocking half shells. The testing involves the controlled detonation of cast mixtures of Cyclotrimethylene-trinitramine (RDX) and 2,4,6-Trinitrotoluene (TNT) in conjunction with siliceous compounds to produce nanocrystalline diamond and silicon carbide. Alternative detonation environments including the presence of a cooling medium such as water or dry ice to absorb residual, post detonation, thermal energy and enhance the stability of the materials being produced have improved yield. Modifications to the explosive charge composition have an effect on the type and quantity of materials that can be produced. Doping of explosive charges with various organic and inorganic compounds has shown promise in the synthesis of materials that are difficult or uneconomical to produce through other methods. This paper outlines the process development of detonation synthesis facilities. Preparation of the pressure vessel to create a suitable detonation environment for the production of nanomaterials is examined. Formulation of explosive charge compositions and considerations involving test charge initiation are discussed in detail. Experimental results and analysis from initial testing as well as plans for future research are also evaluated.

Jan 1, 2018

By Benjamin Cebrian

The new technology presented in this paper is a patented system that is installed on board excavators (backhoe or front shovel types). Several control points are set along ore/waste contacts and their position is uploaded on the corresponding shovel. The operator proceeds on mucking until he is alerted when reaching any of the several control points previously located in the blast patterns and that have moved with the muckpile. A case study is presented at a high grade copper mine, were unique 3D shapes are showing as a result of using an on-board excavator dilution control system. Both ore-loss or dilution cost of opportunities are analyzed.

Feb 1, 2020

By Sam Oaks, David A. Smith

The new Corridor "G" Federal Highway Project in Logan County, West Virginia is the largest mass excavation highway project currently being built in the United States. Seven sections covering 14 miles of four lane highway and two connector roads will require over 30 million cubic yards of excavation. Construction is on a fast track schedule requiring the contractors to complete excavation and pavement placement in a little over 19 months. The two different general contractors have implemented several innovative Blasting and Excavation Programs to complete this project within the tight completion schedule. The paper expands on some of these unique programs that made the project a reality.

Jan 1, 1994

By William A. Travnik

For more than 60 years, ESSO RESOURCES CANADA LIMITED has been producing and refining oil at a small refinery in Norman Wells, Northwest Territories, and supplying diesel fuel and other oil products to northern markets. In 1982,ESSOwas granted governmental approval to expend production from the oil field from 475 cubic metres a day to 4400 cubic metres a day. This $800,000,000projectproceeded ahead of schedule for a start up in 1985.

Jan 1, 1986

By Leslie Taylor, Kevin Genson

This paper reports on an experimental study of the effect that bottom shaping might have on the impulse delivered to a light armored vehicle due to a buried mine detonating beneath the center of it. The study was restricted to explosives buried in saturated sand and three parameters were varied within the study: bottom angle (0 degrees to 21 degrees), depth of burial of the explosive (1.02 mm to 12.7 mm), and stand off distance (0 mm to 38.1 mm). Six hundred and thirty six milligrams of explosive was used as the explosive load. It has been shown in previously published work [1,2] that Hopkinson scaling works well for the determination of impulse loading on a semi-rigid target plates. Therefore in terms of a full scale test using 4.54 Kilograms of explosive the parameters investigated would cover a DOB of from 19.56 mm to 243.84 mm and a Stand off distance from 0 to 734.06 millimeters. These values nicely cover those of interest to the Marines with regard to the AAV (amphibious assault vehicle). Four angles were investigated at all DOB’s and Stand off distances – 0 degrees, 7 degrees, 13 degrees, and 20 degrees. The results show that reduction in impulse delivered to the target is achieved with an angled bottom on the target plate with a major reduction occurring before the 13 degree angle is reached. Hence vehicles with quite modest bottom angles could help greatly in load reduction with very little loss in utility.

Jan 1, 2008

In the March/April 2006 issue of the Journal, we published an ethical dilemma called “Blowing the Whistle.” We received many interesting responses to the article as requested. Some of the responses are printed here. We’ve also included “Blowing the Whistle” again in this issue as a refresher on page 37. Dear Editor, It is in my own personal belief that it would be extremely important if I were the blaster to take the following steps. 1. Hold an immediate emergency meeting with the contractor to convince them to stop work at this point.2. This meeting would need to be held with all powers that be in this construction company. This helps eliminate the hearsay (excluding the farmer). 3. Explain the entire situation to the contractors as it has been presented to the blaster by the farmer. 4. Recommend calling in an engineering or geological firm with the expertise to investigate this matter immediately, and take all immediate action based on findings. 5. Follow up with farmer allow him to speak, (a.k.a. vent) and assure him proper steps are being taken to come to resolve this matter. 6. Be a good listener, and communicator with the farmer while investigation is being conducted. 7. Should the contractor not want, or take any of these recommendations, the blaster himself and his company should question even working for this company ever again. This in itself would not be the class of people we would want to be associated with EVER.

Jan 1, 2007

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 Dale Preece, Stephen Chung

The DMC-BLAST (Distinct Motion Code) has been developed for modeling bench blasting to one or two free faces such as choked blasting in surface gold operation and cast blasting in coal mining, respectively. This computer code has been used to assist the analysis of rock mass displacement after a blast was initiated in an orderly delay sequence. Applications of this feature can be found in the studies of dilution control in surface mining of gold as well as coal involving complex rock structures. Recently, DMC-BLAST has been modified to include a designated delay firing order coupled with variable rock strengths in the blasted media. This newly added feature allows the investigation of the effects of delay firing order on rock displacement in blasting a complex interbedded ore-waste structure. Examples of blasting a steeply dipping coal seams and bedded rock structure, especially in coal mining operations will be addressed and the comparison of efficiency in blasting in an up-dip as opposed to blasting in a down-dip direction will be discussed. Also covered in the paper is a new application of DMC-Blast to simulate a stope blasting underground. Simulations of blasting in a few selected types of timing/structure combinations will be presented in this paper.

Jan 1, 2000

By Amanda Verno, Danilo Coppe, Andrea Reggiani, Adolfo Bacci

The methodological example that comes from the demolition of the Genoa grain silos, should not been considered as an auto-celebration of a difficult project successfully executed, but should serve as an example of a new generation of demolitions where different technologies, often in competition, come together to obtain the optimal solution of a problem. Dynamite, diamond wire and hydraulic excavators overcame the most impressive building in town, working in very little spaces and on a geotechnically difficult site; moreover, a study on the dynamics and the effects of the impact of the structure, an analysis of the presence of potentially explosive dusts and an extensive vibrometric monitoring supported the design and the development of the operations.

Jan 1, 2005