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By R. J. Cefalo

Blast and mining spillover between phases or critical areas of the pit is a continuing problem in the mining industry and a safety concern for operating mines. The challenge for many mines is to produce the highest value in the shortest amount of time for any project. For any project, the top priority of any mine is producing ore as fast as possible. The next challenge is to keep that ore feed continuous. To achieve continuous ore feed, pits are designed with multiple phases that are connected and are mined at different elevations. This difference in elevation causes dangers with spillover between the phases during mining, drilling, and blasting. This paper covers an incident that occurred at an active mine and the work completed in creating a spillover control program over an active mining phase. The drill and blast technical group was responsible for creating blast patterns to reduce spillover between these phases. Unrealistic goals and expectations were initially set for the area of the pit. The drill and blast technical group needed to figure blast objectives and work with the geotechnical team to align with these goals. This paper will go over the executed example of setting up spillover targets and expectations for multiple sections of an operating mine. Different sections of the pit had different control measures and blast objectives due to narrow laybacks and double benching. The use and value of blast objectives and goals were beneficial in setting expectations and measuring design success. Having unrealistic blast goals can set up the operations to fail or get frustrated in trying to work on an impossible task. The problems and risks of phase interactions for many open pit operations need to be considered in the design process, along with designed controls that minimize the probability of any safety incident. Mine designs are being created in the industry and do not consider phase-to-phase mining interaction and the impact it would have on safety or production. The best future for safer mines is blast patterns that reduce spillover between phases of mining and pit designs that might account for spillover interaction.

Jan 1, 2024

By Calvin J. Konya

When blasts are designed, we normally assume the best case situation. We assume that all burdens and spacings will be properly drilled, holes will be properly loaded, initiators will fire at the nominal time and the explosives will release their full energy. This type of precision can be obtained at a machine shop where precision equipment is available to do machining, however, in the field, no matter how well a blast is designed on paper, it most likely will not be done in the exact manner in the field.

Jan 1, 1990

By Frank Lucca

This study is based on a six month study performed for Lee County, Florida. The study was based on blasting for land development and how this type of blasting affects structures. The study is investigates peak particle velocities and the relationship to other environmental and manmade forces that affect structures. The study also explores the effect of geology on blast vibration. After completion in Lee County, the study was then continued in the quarry environment in Vermont and extremely tight blasting environment of New York City. Charge diameters were 127mm (5 inches) or less.

Jan 1, 2006

By Ralph E. Burnham, J. Kelly Ratliff

"The words “dynamite,” “TNT,” “explosives,” and “blasting” typically cause the general public, andjurors, apprehension and fear. Although blasting operations conducted by well-trained, skilled, andexperienced blasters rarely cause damage or injury, the public’s perception of blasting is that it isdangerous, disruptive, and results in damage to nearby properties. As a result, blasting operations have always resulted in complaints, claims, and lawsuits. However, in recent years, the public perception combined with an increase in public opposition, social media, more stringent regulations, predatory plaintiffs’ attorneys, and the application of strict liability to blasting claims has resulted in an increased threat of litigation to blasting companies and individual blasters. Consequently, many blasting companies find themselves receiving more complaints, involved in more litigation, and facing an alarming number of frivolous claims, which can result in increased insurance costs and other financial tolls. Accordingly, today’s blasting companies must be prepared for litigation and take steps to eliminate accidents and claims before the first shot is detonated on a job. The best way to accomplish this is standard operating procedures that incorporate best management practices, industry standards, and regulations in daily operations. This paper outlines some of the considerations that a blasting company should incorporate into its standard operating procedures before, during, and after the shot."

Jan 1, 2016

By Donald C. Clark

The Blasting Contractor as an Insurance Risk involves a discussion of changing times in the insurance market and changing methods of operation in the construction industry. Since the advent of Internal Revenue Service~1 and Occupational Safety and Health Act~2 regulations by the Federal Government in the early 1970's, operations have changed. Many small users of explosives have discontinued any use in favor of subcontracting the drilling and blasting to specialists. This change in operations along with the change in the insurance market has created coverage problems which is the subject of discussion of this paper. Although no definite conclusions are reached, it is an attempt to promote understanding and further the efforts toward equitable solutions.

Jan 1, 1977

It has been common practice for many years to predict and control underwater blasting effects on the basis of certain simplified theories related to the pressures generated by underwater detonations. Unfortunately, two of the most commonly applied concepts in many instances do not provide an accurate modeling of typical field conditions nor the potential for damage. One of these concepts is that the damage potential is related directly to the peak pressure generated by an underwater detonation, without regard to the time history of the pressure pulse. This belief has led to the widespread use of air bubble curtains to reduce peak pressures, without considering the effect that air curtains have on the time history of the pressure pulse. At times, this procedure can be unwise. The other concept is based on the premise that pressure pulses in solids (such as rock) will always be transmitted to nearby water bodies in agreement with the theories of the transmission of plane waves across normal (perpendicular) boundaries. In reality, such conditions are quite rare.

Jan 1, 1985

By J Edmund Hay

Previous work by the Bureau of Mines to develop a test for determining the initiating strength of commercial detonators has been modified and extended. Recently reported results by the Bureau used a homogeneous liquid explosive to avoid the complicating effects of inhomogeneities; however, due to the belief that there may be essential differences between the initiation mechanisms of simple liquids and multi-phase mixtures and the fact that almost all commercial explosives are in the latter category, the experiments have been modified accordingly. The acceptor explosive is now a mixture of explosive-grade ammonium nitrate (AN) prills, methanol (MeOH) and nitromethane (NM). An additional change has been the use of the United Nations (UN) cap sensitivity test configuration in which the detonation witness is the degree of compression of a lead block, which is a quantitative measure of the response of the explosive. Results indicate that this mixture has sufficient range of sensitivities to be useful in comparing the strength of commercial electric detonators.

Jan 1, 1993

By Ray Heater, Qian Liu, Alan Bauer

The channel effect is a phenomenon that takes place with decoupling explosive charges; an air shock wave propagating ahead of the detonation wave in the annular space around the explosive charge compresses the charge so that the process of detonation is modified and even stopped. For commercial explosives, such as AN/FO slurries and emulsions, the channel effect causes partial detonation under certain conditions. To simulate and evaluate the phenomenon, a hydrodynamic model was developed based on the assumption that the pre-shock wave is produced by Mach reflection at the tube walls. Based on instrumented experimental studies with the above explosives in diameters ranging from 25 to 90 mm in pipe sizes ranging from 35 to 127 mm, it has been possible to demonstrate that a criterion for failure based on a critical impulse concept fits the experimental data well. Critical impulse values for the various explosives tested are presented along with the necessary correlations between charge and borehole diameter required to produce this.

Jan 1, 1988

By Paulo Couceiro

Highly non-ideal explosives usually tend to react expressively below their ideal detonation velocities. In these cases, dimensional effects and product heterogeneities become important to proper model the detonation state. Although Direct Numerical Simulation (DNS) techniques can provide a complete and exact solution for this problem, its actual computation cost is still not practical for industrial applications. In order to minimize these constrains, a simplified two-dimensional steady non-ideal detonation model for cylindrical stick explosives is developed.

Feb 1, 2020

By Ruilin Yang

Techniques for the study of blast vibrations, such as monitoring, analysis, and modeling are often misused between near field and far field blast vibrations. This paper discusses the differences between near-field and far-field blast vibrations in terms of these techniques. A typical example of a near-field blast vibration problem is a blast vibration in the crest of a new highwall behind a cast blast. In such a case, the blast can be a couple of hundred feet long and the distance from the blast holes to a monitoring station may only be 100 feet or less. In this situation, the size or spatial geometry of the blast is not negligible compared to the distance from the blast to the vibration monitoring point. On the other hand, a typical example of a far-field blast vibration problem can be a quarry blast with a nearby residence house. In this case, the distance from the blast to the house may be several thousand feet. The size of the blast is less than a couple hundred feet long and negligible compared to the distance from the blast to the vibration monitoring point.

Jan 1, 2007

By R D. Skaggs

A good blast is dependent on a well engineered design. However, a good design's performance depends on the control of the drilling and loading of the blast holes. The key stone to good blasting is the drilling of straight holes of the correct orientation in the required positions.

Jan 1, 1991

By Hans Perlid

In the handling of emulsion explosives pumping is a key operation. A number of serious accidents has shown that pumping can be a risky operation and should be care&lIy considered and investigated. This is the background behind a series of pump tests carried out by NTTRO NOBEL.

Jan 1, 1996

By Dal Sun Kim, Michael K. McCarter

"Comminution (crushing and grinding) of rock materials is energy-intensive and expensive. Mucheffort has been directed to improve the efficiency of conventional milling practice, but relatively littleattention has been given to the potential benefits of blast-induced damage on comminution processes. To help assess this effect, research has been conducted at the IRECO Laboratory and the Generic Center for Comminution at the University of Utah. The objective of this research is to investigate the effect of shockinduced “crack-like” damage on rock properties and subsequent breakage efficiency for three petrologically different rock materials under laboratory conditions. In order to evaluate the effect of shockinduced damage, a quantitative measure of rock damage is needed. For this purpose, a scalar variable (0) is proposed."

Jan 1, 1993

By K. Ram Chandar, Vedala Rama Sastry

Fragmentation and muck pile profile together play an important role in optimizing the excavation costs for given geo-mining conditions. Initiation system is one of the vital parameters influencing the fragmentation and muck pile throw (profile). An attempt is made through this paper to study the characteristics of muck pile produced in addition to fragmentation. Two new parameters namely “throwburden ratio” and “muck pile ratio” are proposed for assessing fragmentation and movement of material. Field investigations were carried out in a limestone mine in southern India with shock tube and detonating cord initiation, using four initiation patterns, keeping other parameters like burden, spacing,delay timing etc. same.

Jan 1, 2008

By G Dean Barrett

Just one year ago at the 1986 Annual Meeting of the Society of Explosives Engineers, Dr. Calvin J. Konya presented a paper entitled "Presplitting Granite Using Pyrodex, A Propellant.'' Since that time more evidence has been developed to support the concept that "...gas energy can be the principal splitting force and that the stress wave or shock wave is not necessary to cause the presplitting action to occur." Work done in Vermont and Georgia is presented, and the ability to split granite without causing radial cracking of the bore holes is demonstrated.

Jan 1, 1987

By Gordon M. Matheson, David K. Miller

Sinkhole development in karst terrains is a serious problem and risk to facilities built in these areas. The potential for sinkholes are a function of many things including the chemistry of the underlying rock, the location of water conductive fractures and fissures in the rock, the natural fluctuation of the ground water table, vibrations from various sources and surface regrading activities. When sinkhole open near quarry operations the occurrence of these features is occasionally attributed to vibrations from quarry blasting. The purpose of this paper is to review the evidence regarding the development of sinkholes as a result of quarry blasting. In general, it has been found that sinkholes result from collapse or piping of overburden soils into cavities or caverns developed within underlying carbonate rocks that have been in existence for many thousands of years. The overburden soils in karst areas are typically clayey and as a result are not subject to densification or liquefaction as a result of vibrations. The primary cause of an increased rate of sinkhole development can be attributed to changes in the ground water table or local surface water drainage. These changes may be caused by seasonal fluctuations, ground water level lowering in drought periods, dewatering of excavations or quarries, or local changes in surface drainage resulting from grading activities.

Jan 1, 1998

By Claude Cunningham, Szendrei

The partitioning of blasting energy into “Shock” and “Heave” components is a popular concept for attempting to match explosives to particular ground conditions and blasting results. The issue is complex, as it affects both the detonation process and the immediate response of the rock skin. However, the fundamental process of energy transfer from the explosive to the rock through the blasthole wall is not well defined. Clues to the “Shock” phase of blasthole expansion are given by cratering behaviour of materials subject to high velocity penetrators. The final cavity volume defines both the energy used to achieve this and the resistance of the confining material. Attention is being given to the link between penetration of a solid target and expansion of a readymade hole, both producing the same outcome. The benefit of this work is that it leads to clearer understanding of how explosives will impact upon the blasting results and helps to explain the energy consumption in blasting.

Jan 1, 2004

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 N K. Jain

"The idea of writing this article is to give correct picture about the technique in blastingindustries based on the safety aspect, basically without effecting the results thereof.Like many other sciences, blasting is rapidly advancing and research scientists are dailycreating new devices which are very reliable and efficient.The theory of explosion and all the respective changes caused by the explosives takingplace during the detonation has been brought up to the level enabling a mathematicalexpression of detonation characteristics even in comparative complex cases."

Jan 1, 1993

By John L. Floyd

A personal computer is a valuable tool for blast design and analysis. Programs designed for the personal computer, such as the electronic spreadsheet, can be used for a wide range of applications. The spreadsheet formats discussed in this paper are used for explosive comparison, inventory/shot records, and timing design analysis. Each template can be adapted to fit the individual needs of the end user. An example of a graphically orientated blast design program, written in the BASIC programming language, is also discussed.

Jan 1, 1987