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By Dennis R. Jr Bell

Before beginning any site development or mineral extraction activity, it has been well documented that it is first prudent to gain an understanding of the prevailing geologic conditions.Whether it’s identifying the depth to type of bedrock, or determining the quality and quantity of the in place mineral deposit, these factors should always be considered in a project’s fatal flaw analysis. In situations where there is limited subsurface information, geologic models have been proven to be one of the most valuable and cost-effective tools used by the developer and/or his consultant.

Jan 1, 1997

By Chris Breeds, Larry Leone, Jerry Wallace

Project Owners typically require General and Detailed Blast Plans when blasting close to important structures and specify the maximum allowable peak particle velocity for each potentially affected structure. Low, residential level PPV limits may be specified which significantly restricts the potential for blasting to be effectively used. Contractor’s responding to these contract conditions typically cite historic case studies which may, or may not, apply to the specific situation and/or types of structures for which limits have been set. A long submittal cycle typically follows.

Jan 1, 2010

By Alastair C. Torrance

"A brief review of the Australian mining industry is given followed by a more detailed treatment of a study of the influence of primer Size on explosive performance. This is based on a joint research programme conducted by BHP Central Research Laboratories and Dyno Wesfarmers Ltd and examined the effect of the size of cast primers on the run up and steady state detonation velocitiesof ammonium nitrate based explosives as a function of blasthole diameter. The field trials examined a numter of the Dynamo 'Westfarmers HDF series of primers in conjunction with ANFO, emulsion and watergel explosives. Results indicate that the iun up velocity of 187 mm diameter ANFO charges is negligible using cast primers as small as 150g. However, emulsion and watergel explosives did exhibit run up in both 187 and 3:1mm diameter blastholes, independent of the size of primer. This could last from 7 to 10 blashole diameters"

Jan 1, 1991

By James A. McGrath

"The predominant key word associated with all commercial blasting methods is “safety”. Safetyshould take precedent over all other aspects of the entire explosives industry which on a wholehas had an excellent track record as to number of injuries per unit of hours worked at all blastsites throughout our country."

Jan 1, 1999

By B Brown, P J. Hommert, B J. Thorne

"Early attempts at estimation of stress wave damage in blasting by use of finite element analysis met with limited success due to numerical instabilities that prevented calculations from being carried to late times. A"" improved damage model based on microcrack growth in tension allows finite elementcalculations which remain stable at late times. Estimation of crater profiles for blasting experiments in granite demonstrate successful simulations with this model."

Jan 1, 1990

By Dale S. Preece, Lee M. Taylor

Accurate computer prediction of the muck pile produced by a conventional blast requires modeling of the physics that occurs during the rock motion phase of a blast. The ability to predict the motion and the subsequent muck pile can have a significant economic impact on the mining industry.

Jan 1, 1990

By M. Hagfors

On the underwater testing of explosives, the measuring system consists of water filled test pond, tourmaline based pressure sensor, measuring cable and measuring unit, which supplies the DC current to the pressure sensor. Depending on the length of the measuring cable, it is always possible that some signal damping may occur in case the measurements are carried out without the signal amplifier to keep the measuring system as simple as possible. Therefore the length of the measuring cable should always be as short as possible.

Jan 1, 2006

By Choon Sunwoo, Chang-Ha Ryu

There are various methods available for the recovery of dimensional stone in open pit quarries. Explosive blasting has more advantages in the economic point of view over the other methods but was not widely used in Korea because owner was concerned about much economic loss when it failed. Several years of efforts have been made in order to develop more effective cutting methods and to spread to the quarries for strengthening the competitiveness in the market. Rock cutting by jet flame and black powder was generally used in the early stage. Black powder was applied to cut the last horizontal plane after forming other vertical planes using the jet flame. Jet flame operation, however, is time consuming and produces excessive noise, and as the result, brings adverse effects on the operator as well as the complaints from the residence adjacent to the quarry. Some mechanical methods such as the slot drill, diamond wire saw or in-situ scale of diamond saw cutting were introduced. Most effective cutting methods using the explosive blasting were developed and applied successfully. Black powder was replaced with the detonating cord. A new air decking technique where plug was not used was developed. This paper reviews the technology for dimensional stone cutting and case study in Korea.

Jan 1, 2003

By Rob Farnfield, William Birch, Douglas A. Anderson

In the blasting industry, even to the most safety conscious shotfirer, misfires are a constant source of concern. In the United Kingdom, there are two types of misfire, as classified by the Health & Safety Executive. Type A occurs when testing a shot before firing reveals broken continuity that cannot be rectified. However, due to the fact that a majority of quarries use non-electric initiation [i.e. shock tube] that cannot be tested, this type of misfire is very unusual.

Jan 1, 2016

By P D. Katsabanis

This chapter describes the principles for the derivation of the equations for a detonation wave. The importance of the equation of state for the detonation products is demonstrated and commonly used equations of state are discussed. Furthermore a brief introduction to the TIGER code is presented.

Jan 1, 1991

By Michael S. Wieland

This report focuses on the U.S. Bureau of Mines research regarding desensitization and malfunction of delay detonators and cap-sensitive explosives. Delay blasting in underground coal generates tremendous shock waves and rifting forces that fracture and heave coal. The shock waves from charge explosions radiate outward in all directions through the coal, impacting neighboring charges with later delays. The impact phenomena have debilitating effects, causing degrees of reduced charge performance ranging from misfires or weak detonations to out-of-sequence detonations. Impaired charges react poorly, fracture less coal, and produce fumes with higher toxicity. Coal-mine, underwater, and simulator tests were conducted to more thoroughly understand the shock damage mechanism. Recently the U.S. Bureau of Mines partially resolved the malfunction problem by demonstrating the feasibility of formulating a rugged explosive. This rugged cap-sensitive candidate passed the requisite tests for certifying an underground coal-mine explosive. With natural aging the formulation rapidly lost initiation sensitivity. The charge formulation had to be rebatched to finish the testing and therefore could not be certified.

Jan 1, 1992

By W. J. Birch, R. Farnfield, L. Bermingham

Whilst a significant body of research has been carried into air overpressure levels that arise as a result of the use of explosives, few published studies have actually tried to relate the movement of a quarry face to the resulting air overpressure produced. The aim of this preliminary investigation was to monitor a number of quarry blasts at two different limestone quarries. The first using multiple separately initiated deck charges in a multi borehole blast, the second using single column charges in a multi borehole blast.

Jan 1, 2008

By W B. Gregg

The rock blasting and mining industries use a system of detonators and explosives for mining operations. Many detonators use small metal bridgewires, which are heated by passing a current through the wire, heating and igniting the pyrotechnic powder in contact with the wire. Typical bridgewires require a current of at least 3 amps, applied for a few milliseconds, for an explosive output. The semiconductor bridge (SCB), in comparison, initiates an explosive in 0.01 to 0.1 of a millisecond.

Jan 1, 1994

By Rudi Toba

Several areas at the DOZ haulage were observed for the crusher’s location. Initially the new crusher designed position was west of the crusher 1, but due to concerns of the mine crack zone (deep MLZ) the crusher position moved to the south. The new crusher location is situated in a diorite rock massive between 3053 – 3079 levels, with the overall excavation of 2500 cum and dimension of 14m long, 14 m wide and 14 m high. Main Crusher chamber itself excavated by development jumbo in three lifts. Development of access to the bottom crusher was developing the same time as chambering the top crusher. The pocket of the crusher mined with vertical crater retreat system which is initiated in one time after middle slot raise. Collaboration between production and perimeter blast holes to be obtaining in control the actual cuts as per the design shape.

Jan 1, 2007

By A N. Gupta, C Joginadham, P Shiva Shankar

Cast boosters made with pentaerythritol tetranitrate(PETN) and trinitro toluene(TNT) give high velocities of detonation and are sensitive to initiation even under high pressures. However, the manufacture of the same involves heating of TNT to its melting temperature and mixing of dry PETN in it.

Jan 1, 1996

By Randy Wheeler

One of the more difficult topics to address concerns the effects of vibration on historic structures. Not only blast induced vibration, but also vibration from other transient and semi-continuous sources like, traffic, human activity, and environment forces. A common question might be, “What level of blast-re l a ted PPV is considered safe?” A review of some of the papers available from the ISEE Explosives Reference Database on CD ROM shows that 0.50 inch per second was often used. It was not clear on what basis this value was selected except that it represents the low frequency limit for plaster developed by the United States Bureau of Mines in RI 8507. In another case, a limit of 0.20 inch per second was mentioned, apparently simply because it was ten times less than 2.00 inches per second.

Jan 1, 2004

By E. McCullough, D. Preece, M. Ortel

Geophysical explosive charges are used in mineral resource exploration. They are detonated subsurface and radiate sonic waves into ground monitors, which detect the vibration waves and their interaction with underlying geologic strata. Geophysicists perform computer analyses of the waves reflected from the strata to determine their depth and thickness (Strobel, Berger & Schaefer, 2012). The purpose of this research is to determine how the detonating explosive charge interacts with the adjacent ground and how the induced waves propagate through the surrounding medium. Furthermore, it is necessary to optimize the location of the initiation point within the charge. Establishing both the direction and intensity of the waves will allow geoscientists to refine and optimize geophysical studies that employ explosive charges.

Jan 1, 2013

By Rob Famlield, Gavin Yuill, William Birch

The Blasting Research Group at the University of Leeds, in the United Kingdom, continues to be highly active in the area of the environmental impact of blasting. In recent years a major part of this research has been concerned with the use of linear superposition. This technique relies upon the assumption that all the holes in a blast produce identical vibration signals. Previous work at the University has shown that this assumption is not sufficiently robust to be generally applicable. This is due to a number of factors of which the key variable appears to be dynamic confinement

Jan 1, 2002

By Braden T. Lusk, Rex A. Meyr, Kyle A. Perry

Following three major mining accidents in 2006, the MINER Act of 2006 was enacted by MSHA and required every underground coal mine to install refuge alternatives to help prevent future fatalities of trapped miners in the event of a disaster. A polycarbonate safe haven wall for use in underground coal mines was designed and modeled using finite element modeling in ANSYS Explicit Dynamics to withstand the MSHA required 15 psi (103.4 kPa) blast loading spanning 200 milliseconds. The successful design was constructed in both half-scale and small scales in the University of Kentucky Explosives Research Team’s (UKERT) explosives driven shock tube. The constructed polycarbonate walls were tested multiple times to determine the walls resistance to blast pressure. The results for each test were analyzed and averaged to create one pressure versus time waveform which was then imported into the finite element program and modeled to compare deflections of each part to that was measured during testing for model validation. This paper summarizes the results.

Jan 1, 2014

By P D. Kasbanis, Lyall Workman

"The energy output of an explosive is typically calculated using an equation of state and computerapplications. Results are reported as weight and bulk strength, either in absolute terms or relative toANFO. The effect of the equation of state selected and the assumptions regarding the energy calculation are considered and interpreted for the purpose of blast design. It appears that variations in the heat of detonation which result from the selection of the equation of state and parameters associated with it are not sufficient to significantly affect blast patterns, explosive consumption and costs. However variations stemming from the use of “available energy” associated with a cut-off pressure are significant, suggesting in many cases large pattern expansions. The validity of the various approaches is discussed and blast design results based on the energy calculated by the different approaches are presented and evaluated."

Jan 1, 1996