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By : D. Lawrence

Certain blasting applications are more prone to the generation of significant levels of nitrogen dioxide post blast fumes, more commonly referred to as after blast smoke, generally ranging in color from dark yellow to bright red. This paper reviews basic background chemistry defining the observed fumes and attempts to correlate geology, blast design, and explosive composition effects on the level of nitrogen dioxide that can be observed in various blasting conditions. Additionally, a test setting for evaluating the generation of post blast fumes is presented with pertinent test data detailing generic explosive formulation modifications which effect the overall level of post detonation generation of nitrogen dioxide.

Jan 1, 1996

By Marcello Crispi, Valdir Silva, Juarez Moraes

Companhia Vale do Rio Dote - CVRD is the largest mining company in Brazil and the largest iron ore producer in the world. Serra Geral Mine (SGM) is located at Iron Quadrangle of the State of Minas Gerais, approximately 80 kilometers from Belo Horizonte. Hematite and Itabirite are the two main minerals. A blasting with a spherical charge has been introduced at Serra Geral Mine, an iron ore producer in Brazil, belongs to the CVRD (51%) Kawasaki Steel Corporation (24.5%) others (24.5%), in order to improve fragmentation, as well, load, transportation and crushing productivity. This paper will present the results of a successful blast design with a spherical charge carried out by Serra Geral Mine, the Department of Mining Engineering at Escola de Minas - Federal University of Ouro Preto-UFOP associated to a Blasting Engineering Consultant. The results obtained in the field tests and how it was possible to increase the blast pattern in 53%, which allowed one reduction around 31% in the cost of blasting operation in the Serra Geral Mine, will be discussed in details.

Jan 1, 2002

By John Brown

Let’s talk about things that you, the driIl boss, the pit boss and the driller can do to eliminate the trend in drilling related accidents that have come to plague our industry in recent years. My paper will focus on reaI issues, problems and solutions that will affect our everyday outlook and attitudes about our jobs and lives. There are some real hard facts we must address if we are going to reverse this terrible killing trend.

Jan 1, 2000

By X Meng, W. A. Hustrulid, M. K. McCarter

Rock excavation in both surface and underground mining is largely accomplished using the drill and blast technique. At the perimeter of such excavations, cautious blasting procedures are often employed to minimize unwanted damage to the remaining rock. Of the several different techniques available, the use of explosive charges with a diameter smaller than the holes in which they are introduced (so-called decoupled charges) is the most common. In spite of the long and widespread use of the technique, a technically sound basis for relating the borehole wall pressure to the explosion pressure is still lacking. Such a relationship is required for optimal design

Jan 1, 2005

By Thomas Leonard, Philip R. Berger, Bryan E. Papillon

Bardon Trimount Inc., a large producer of aggregate, crushed stone, and concrete, was experiencing significant public opposition to its five quarries in the Boston area. It was believed by the authors that this opposition could be significantly lessened if the total number of blasts per week were reduced. Although the blasting company at these quarries, Austin Powder Company, contended that this could easily and safely be accomplished by increasing the size of the blasts, regulations precluded this alternative by limiting the total amount of explosives that could be used per blast.

Jan 1, 1996

When a company has an effective hearing loss prevention program, everyone wins-the employers, the employees, and the safety and health professionals who implement the program. This guidebook is not about minimal programs that meet only the letter of the law. It is concerned with programs that are effective as well as efficient: those optimizing program elements that succeed in preventing hearing loss in a practical and cost effective manner.

Jan 1, 2006

By Dong-Hyun Kim Kim, Tai-Ro Lee, Young-Hwa Seo

Overbreak occurred inevitably in a tunnel excavation, is the main factor for increasing cost and period in tunnel projects. Furthermore the damage to the remaining rock mass related to the overbreak can give rise to a serious safety problem in tunnels. As a rule of thumb, causes for the overbreak are inaccuracy in drilling, the wrong design of blasting and selection of explosives, and heterogeneity in rock mass. Specially, the geological features of the rock mass around the periphery of an excavation are very important factors, so a lot of research has been conducted to describe this phenomena. But the geological rockmass classification for the overbreak and the method for decreasing the overbreak have not been fully established. Besides, the technical improvement of the charge method is needed as explosives for the smooth blasting have not functioned efficiently. In this study, the working face around periphery of an excavation has been continuously sectionalized to 5~ 6 parts, and the new Blastability Index for the overbreak based on 6 factors of RMD(Rock Mass Description), UCS(Uniaxial Compressive Strength) JPS(Joint Plane Spacing), JPO(Joint Plane Orientation), JPA(Joint Plane Aperture) and FM(Filling Material) is proposed to classify sections of the working face. On the basis of this classification, the distance between contour holes and the charging density are determined to minimize the overbreak. For controlling the charging density and improving the function of explosives, the New Deck Charge(N.D.C) method utilizing the deck charge effect and detonation transmission in hole has been developed.

Jan 1, 2003

By Lee B. Paterson

Mining Engineers throughout the world have an appreciation for the importance of the role of the Blasthole Drill in one of the primary elements of the mining process. This paper highlights areas that could influence the overall cost effectiveness of that process of breaking rock and the associated downstream mining and ore recovery activities - and how the drill is designed and configured to meet that challenge. Factors influencing drill productivity and overall cost effectiveness are addressed, particularly regarding the benefits which are not necessarily reflected in the drilling process and therefore more difficult to quantify. This paper explores some of the downstream benefits of what we do to the drilling process.

Jan 1, 2000

By Billy J. Thorne

The damage model in PRONTO simulates the dynamic fracture behavior of brittle rock. It is based on work started by Kipp and Grady, [lg] continued by Taylor, Chcn and Kuszmaul [I91 [20] and recently.modified by B. J. Thorne (first documented here). The essential feature of this model is the treatment of the dynamic fracture process in rock as a continuous accrual of damage in tension, where the damage mechanism is attributed to microcracking in the rock medium. The fundamental assumption of the damage model is that the material is permeated by an array of randomly distributed microcracks which grow and interact with one another under tensile loading.

Jan 1, 1989

By Pertti Paavola, Hikki Rasanen

This paper describes a very exacting tunneling project. Planning and technical realization of this service and transportation tunnel was especially difficult as a matter of vibration control, because the tunnel is situated only a few meters under Maria Hospital, which is one of the most busiest hospitals in Helsinki. In this hospital there are many departments for bedpatients, research and treatment with high-tech equipment, operational surgery and a big laboratory. Besides access tunnels are situated near several apartment buildings. The functionality of the tunnel required the placement of the access tunnels to be straight towards these apartment buildings for which special care for blast induced air pressure had to be taken.

Jan 1, 1997

By Richard Brummer, John Hadjigeorgiou, Patrick Andrieux

Some of the major challenges associated with underground mining at depth and/or under high extraction ratios are related to the resulting high stress levels, which can lead to the failure and collapse of the rock mass surrounding the excavations. Sudden and violent failures, which can have severe consequences, represent the highest degree of difficulty in terms of underground personnel exposure, erratic and unpredictable production, ground rehabilitation requirements, possible reserve losses and overall mining costs.

Jan 1, 2012

By Bruce Vandenberg, R F. Chiappetta

"The High Speed 2D Analysis program allows the user to bring in data from several different sources. Of course, keyboard entry is included as a source. Other data is inputted through the serial port (X-2321 of the PC. Two types of data are transferred via the serial port. The first is the tablet digitizer data. The three types supported presently are the GTCO, tablet digitizers. and the Calcomp 2500 and 9100 series To transfer digitized data turn on the selected digitizer and place the cursor on the tablet. Enter the High Speed pmg.ram and select from the Input Program menu the Digitize Inputs(20) option and follow the instructions. TO exit the session, either a keyboard entry or a cursor button is pressed. The second type of serial port input Is from the collectors of the listed survey systems. Typically a file transfer program will be used to send the data from the collector to the PC. This topic will not be addressed at this time."

Jan 1, 1989

By William H. Snyer

A relatively inexpensive, very fast response photo-optic/fiberoptic system has been conceived, constructed and employed by Denver Research Institute (DRI) to measure charge breakout uniformity on the surface of a very large ANFO detonation. The new equipment and technique was coined OWL (observation without leads). Its unique design provides the ability to monitor or measure detonation velocities and/or detonation breakout characteristics without fiberoptic or any other direct contact with the explosive. This system has proven to be versatile and has been used to measure surface breakout simultaneity on large ANFO detonations, munition case breakout times and velocity of detonation (VOD).

Jan 1, 1990

By H. Rossmanith

This contribution introduces the fundamental concepts of wave propagation and fracture mechanics which form the basis of electronic blasting, i.e. precise initiation timing using electronic detonators. The concept of Lagrange diagrams will be frequently used for the calculation of the delay time between blast-holes in a row and rows of blast-holes. The effect of burden and structural geology will be briefly touched. It is found that the advanced blasting technology based on the use of electronic detonators introduces a change of paradigm. It will be shown that knowledge in wave propagation and fracture mechanics is essential for the successful application of the new blasting technique in industry. In particular, the delay time, the wave speeds in the rock mass, the shape of the wave pulse and the acoustic impedance mismatch have become decisive parameters in advanced blasting. Utilizing the wave speed and wave shapes of detonations, large scale tests Utilizing the wave speed and wave shapes of detonations, large scale tests in various countries (Australia, Chile, etc.) have shown that optimal delay timing requires shorter delay times in conjunction with allowing for a wider drilling pattern and the use of a reduced amount of explosives, i.e. a lower powder factor. This seemingly contradictory arrangement is fully justified by using scientific principles in blasting, and converting blasting from an art to a scientific discipline.

Jan 1, 2003

By Catherine T. Aimone-Martin, Meyers Joseph A.

A new strain-based criteria is being adopted for rock blasting in New York City (NYC). This criteria is based on several years of research involving vibration measurements of tall structures during blasting within several feet from buildings designated historic and Landmarked. This research has demonstrated that tall, heavy structures show little upper-structure vibratory response during hard-rock, urban blasting carried out in NYC. The Fire Department of New York City (FDNY) permits rock blasting and regulated limits for ground vibrations using the U.S. Bureau of Mines (USBM) safe blasting criteria. However, these regulations are often superseded by a 0.5 in/s (12.7 mm/s) limit imposed by the New York City Department of Buildings for historic and Landmarked buildings that are adjacent to the majority of blasting projects in the City. This onerous limit is often exceeded resulting in frequent stop work orders that increase the cost and time of rock excavation projects. The

Jan 1, 2019

By Kwang-Tae Kim, Yong-Kun Choi, Jeong-Soo Chong, Yun-Jae Lee

An annex building at the former Agency for National Security Planning(NSP) complex located in downtown Seoul was demolished by progressive collapse method. This work was done as a part of efforts to restore the landscape of Namsan Mountain which lies in the Center of Seoul. The five-story reinforced concrete structure was razed in 5.5 seconds by the 29kg of high powered explosives which were placed in some 320 holes in the building with floor area of 2,577 m². The asbetos and all the other finishing materials in the building were removed before the demolition and the specially coated wrap minimized the spread of blasting dust. Seismic and air overpressure waves were monitored at 8 points, which were below safety limits and the continuous communication with neighborhood prevented any complaint.

Jan 1, 1998

By Eduardo Lozano, Vilem Petr

The use of explosives bring countless benefits to our everyday lives in areas such as mining, oil and gas exploration, demolition or avalanche control. However, because of the potential destructive power of explosives, strict safety procedures must be an integral part of any explosives operation. The goal of this paper is to provide a solution against the hazards which unfortunately accompany the use of explosives. For this reason, a blast shield is specifically designed and tested for protecting personnel against these unpredictable effects. This document will develop a complete analysis answering the following questions: what are the potential hazards from an air blast; what are their effects; and how can we be protected against them. In order to answer these questions, theoretical, analytical, and numerical calculations are performed. Finally, a full blast shield prototype is tested under blasting conditions proving its effectiveness as a safety device while explosives are used.

Jan 1, 2015

By Karl E. Burgher

Since World War II, the need for the use of explosives with testing, construction, demolition, mining and quarrying near urban areas has increased dramatically. Once remote, testing areas have been encroached upon by commercial and residential areas. Evidence has been found that overpressure levels near these areas can be estimated using meteorological conditions. This paper reviews a study where 205 test shots were fired, meteorological conditions recorded, and over-pressure levels estimated using multiple regression techniques.

Jan 1, 1988

By Roger Scarr, Richard A. Walker

Interactive video is the combination of computer and laser disc -technologies that allows for the storing of 54,000 single images or 30 minutes of video with the ability to access any segment or single image within a half a second. This capability combined with the use of a graphics overlay on the video and accessed through a keyboard or touchscreen creates a very powerful and versatile marketing or training tool.

Jan 1, 1990

By Bill Williamson, Doug Richmond, Kerri Kuntz, Gus Gilman, Larry Heywood

This was a description by the poet of what occurred over two centuries earlier to Hannibal’s troops as he passed through the Alps. Interestingly, the pass that many feel is the route that Hannibal chose, Col de la Traversette, is the sight of possibly the earliest avalanche mitigation known. Monastery records describe a tunnel built in 1470, near the top of the pass designed to protect pilgrims from the upper slopes. For the next several centuries, avoidance and reinforced structures were the primary tactics to defend from avalanches

Jan 1, 2009