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By K. Hausmann, W. Whelchel

The properties of ethylene Ionomer resins for the inner layer of non-electric shock tubes will be discussed in detail, and opportunities for property enhancement will be pointed out. A stiffness program for prediction of shock tube stiffness, as determined by the stiffness of the individual layers, will be presented and discussed.

Jan 1, 2010

By Michael Wieland

The thrust of this report is to overcome some of the technical deficiency in the scientific methodology that correlates the work output during a charge explosion to the resulting toxic fumes. Thermodynamic work-principle models yield (undissipated) shock and heave results for shooting underwater and in rock stratum with related toxic fumes. Underwater circumstances yield reliable test data for the work process, though questionable or no fume results. Work-output measurements in rock shots remain difficult if not intractable, though some fume reports exist. Underground tests with thick-wall metal pipe bombs yield consistent toxic fumes trapped within the test chamber. The work output, rendered as fragment kinetic energy, can be inferred from the well-tested theory of R. W. Gurney, originally designed for military ordinance. Therefore a work-principle model for cylindrical pipe bombs was developed to predict fragmentation work output and reaction-zone fumes, permitting the double comparisons to reported and inferred results.

Jan 1, 2010

By Wayne Rogers, Sarma Kanchibotla, Alan Tordoir, Bryon Bisiauz, Seth Ako, Eric Engmann

Blast induced rock mass displacement can have a significant impact on ore loss & dilution. The mischaracterization of the grade boundaries both prior to, as well as a result of blasting can lead to significant financial losses on account of ore loss and dilution. Ore dilution occurs when waste material is miscategorised as ore and sent for processing diluting the run of mine head grade and recovery. Ore loss takes place when valuable mineral is miscategorised as waste and sent to the waste dumps, thus never being processed and recovered.

Jan 1, 2012

By C W. "Mickey" Bradley

Thunder strikes terror in the hearts of man and has since the advent of time. We all fear the unknown; even the Greeks created a god, THOR, to be responsible for the thunder and rain. Thunder, by itself, can't hurt anyone; it is simply hot air moving very fast. Thunder, however, is caused by lightning and lightning is what we need to fear and rightfully so. Annually, lightning kills hundreds of Americans, injures another 2,000, damages or destroys approximately 30,000 structures, 1 starts thousands of forest fires and strikes mine properties over 100,000 times.

Jan 1, 1992

By M E. Hanson, K Chong, R H. Jacobson, S C. Way

To create conditions for economic rates of mineral recovery in a deep, hard rock mass, enhancement of naturally occurring permeability is necessary, and may be achieved through explosives detonated in boreholes. Previous theories of explosively created permeability are reviewed and found to relate permeability solely to the degree of fracturing, neglecting porosity. A theory is presented that includes both fracture density and porosity, and its results are applied, together with a knowledge of explosive behavior, to derive design parameters for in-situ mining.

Jan 1, 1983

By Francisco Sena Leite, Raquel Sobral, Vinicius Gouveia de Miranda, Céu Jesus

"This document investigates a newly developed technique with the objective of improving terrain triangulation models (horizontal/sub-horizontal and vertical/sub-vertical terrains), mainly blast free faces. The algorithm uses multi-linear regressions to generate the best point cloud projection plane by applying the residues modulus minimization so as to create the finest 3D triangulation model. A change of base is required to create a new set of coordinate axis and generate completely new projection planes. The projection plane residue analysis is inferred in order to avoid or reduce the outlier points. The dataset is composed of 12 terrain models obtained from photogrammetry and a 3D Laser equipment thatgenerates georeferenced cloud points. This new technique is validated by the analysis of the obtainedcritical burden by the improvement of the general aspect view of the terrains and the capacity of outlier’s detection. The result and the quality of the algorithm demonstrates the improvement in the triangulation mesh, reducing errors in the calculation of over/under burden, free face volumes, cavities and, therefore, in the estimations of clearance/safety distances."

Jan 1, 2017

By Dale S. Preece, Ruilin Yang

"Air-decking has been used frequently in blasting for many decades. It has been asserted that an air-deckcan alleviate excessive shock pressure from the detonation of a charge thereby producing better energy distribution in a blast overburden, for example. Research on air-decking has been active and various theories have been postulated that mostly support the effectiveness of air-decking for improved blast efficiency."

Jan 1, 2017

By Terri Jordan, Kenneth Hollingshead, Mary Jo Barkaszi

The Port of Miami, Miami-Dade County, Florida (Port) is the largest container port in the State of Florida. However, it is located in the center of a diverse ecosystem. Biscayne Bay surrounds the Port and portions of the bay have been designated as a National Park, a Florida Aquatic Preserve and a state Critical Wildlife Area. The bay is home to many protected, threatened and endangered species including the Florida manatee, five sea turtle species, American crocodile and bottlenose dolphin, in addition to important recreational and commercial fish species.

Jan 1, 2007

By Roger Favreau, Patrice Favreau

Without blasting there can be no roads, no hospitals, no factories, not even foundations for homes. Yet in 1960 the only way to design a blast was by trial/error. By comparison, bridges were already designed by calculations before being actually built. This was possible because equations based on the fundamental principles of science existed with which all the stresses in the bridge could be calculated. In 1960 no equations based on the fundamental principles of science existed with which the mechanisms that take place inside the rock mass during a blast could be calculated. Since then the main author made it the objective of his research to seek such equations, and to validate that they gave accurate answers by means of experiments in the field, experiments made in co-operation with mines, quarries and the explosives industry; results have been reported in some 90 publications.These equations now deal with essentially all aspects of a bench blast: the intensity of the shock wave and the fragmentation size distribution throughout the rock mass; the movement of all the fragments into the muck pile; the fly rock and vibrations from the blast; etc.; are presented examples of such equations. They are now assembled into a computer simulator called Blaspa accessible on the Web, with which one can design a blast just as a bridge is designed. An example is presented. The reason to design a blast by simulations rather than solely by trial/error is that if it leads to damage, it is only after the actual blast that the blast design is realized to cause damage. If however the blast design had been simulated before the blast, then the risk of damage is identified before the blast and is prevented by redesigning the blast. Examples of such situations are presented. The need to a void damage is very necessary because the public is becoming opposed to blasting. When a blast does cause damage, and people learn that the blast was designed solely by trial/error even though simulation was available and would have prevented damage, they become even more strongly against blasting; they may succeed in getting a quarry closed. Their objections to unchecked blasting are not unreasonable, especially as simulating a blast with Blaspa on the Web is a very simple procedure.

Jan 1, 2013

By A K. Raina, P B. Chourdhury

Flyrock is the unwanted throw of rock fragments to excessive distances in opencast blasting. The incidence is relative in nature incorporating the distance of objects of concern like structures within and outside the mine, equipment within the mine & near the blast and persons within and off the mine. Several attempts to predict and defi ne fl yrock made worldwide could not address the problem since the phenomenon is not a regular feature in blasting. This probabilistic nature of fl yrock allows for risk calculation. CIMFR, India developed a Factor of Safety based risk criterion (10, 14) for evaluation of throw/ fl yrock in opencast mines that incorporates all the above in terms of distance and allowable limit of throw – which in turn determines the risk. The criterion provides the blaster a tool for mathematical evaluation of fl yrock risk in terms of a Factor of Safety and threat ratio (defi ned for the 1st time), thereby enhancing confidence when blasting. The method is easy to use and has been applied to several mines in India and the results are signifi cant. This paper details the evolution of the concept and its application in three limestone mines of India and the results obtained. The application of the method for defi ning a fl exible danger zone is also discussed.

Jan 1, 2008

By Emily Johnson, Catherine Johnson, Ben Sonpon, Kelly Williams

The effect of length to diameter of the detonator is compared using Ansys/Autodyn 2-D simulations, the results of which are validated experimentally. It was found that higher pressure comes with a larger diameter, because it will result in more explosive energy being allocated out the end of the detonator.

Feb 1, 2020

By Kinross Paracatu, Victor Morais, Luis Marinho, Rolando Fuentes, Lucas Steffen, Leopoldo Muñoz, Washington Vilas

Nowadays, mining operations close to communities face increasingly challenges, especially in their drilling and blasting operations. One of the critical effects are the ground vibrations produced in its surroundings. The impact on the community must be minimized to guarantee the license to operate and, on the other hand, costs must be optimized, and an adequate fragmentation must be achieved to ensure the efficiency of subsequent processes and, consequently, to give sustainability to the business. In this regard, it is necessary that some controlled blasting technique to be performed and the utilization of advanced vibrations models. Currently, it is common in the industry either use of the double decking technique, where very low explosive charges are applied, making it necessary to use smaller drill patterns in order to keep powder factor as per design, which strongly increases the demand for drilling and a consequent impact negative on costs.

Feb 6, 2023

By Jennifer Paukula, Steven Lindsay, S. Joon Kim

String loading is the placement of a bead or ‘string’ of emulsion along the lower edge of a development drill hole. The loading hose extraction rate controls the amount of emulsion placed in each drill hole. This allows a controlled distribution of explosive energy throughout the development round. Center holes are loaded using the slowest extraction rate causing the majority of the explosive energy to be placed in the center of the round. The loading hose is extracted successively faster for the buffer and perimeter holes causing less explosive energy to be placed near the edge of the blast. This causes less damage to the rock mass that remains in place after the development blast.

Jan 1, 2012

The underwater explosions have been used for several decades for the determination of energy content of explosives. This test method is the only one by which shock, fly rock and total energy can be measured separately. It enables to develop the energy content of explosives for different purposes; the military high explosives should contain more shock energy whereas the fly rock energy is very important feature for the blasting explosives. The purpose of this study was to establish a test place for the underwater experiments in an old water filled open pit, to estimate the repeatability of the energy measurements, to calculate the standard deviations and to compare the total energy content of commercial explosives to the theoretical values calculated by the thermo dynamical program. The test method seems to work quite well especially for the homogeneous explosives. The difference between the energy content of theoretically calculated and measured values for the homogeneous emulsion explosives was about -3% and for the dynamite about -5%. The energy difference for the unhomogeneous ANFO was detected to be -19%. The diameter of the charge was 15 cm and it was obviously too small for ANFO to detonate ideally. On the basis of the test results this test method seems to fit best for the cap sensitive, completely homogeneous, spherical charges whose masses are big enough and which are initiated from the centre of the charge. The underwater explosions as a test method is the only one which can separate shock, bubble and total energies from each other and therefore makes it possible to develop the properties of explosives for different purposes which is very important feature of this method.

Jan 1, 2005

By D. Goodings, W. L. Fourney, Bonenberger, R., Uli Leiste

The problem of the maximum depth at which a mine buried in the surf zone or beach zone is a threat to landing vehicles is being studied by Naval Surface Warfare Center (NSWC), Indian Head Division, Naval Research Laboratory (NRL), and The University of Maryland Dynamic Effects Laboratory. The problem was divided into two parts: The first part involves determining how deep a pressure plate mine can be and still detect a vehicle passing over it. This requires determining the distribution of stress within dry and saturated sand when a vehicle passes over a buried mine. The results obtained from that study are presented in a related paper (1). This paper will cover the second part, which entails determining the impulse delivered to the vehicle. This is equivalent to determining the impulse delivered to a plate suspended above the detonating explosive charge and includes an investigation of the distribution of the impulse over the plate. The purpose of the research is to develop a scaling law and/or computational capability which will permit predicting impulse to be expected in the field from tests conducted in the lab. The computational effort is aimed at the development of and confidence in computer codes that can be used to predict stresses and strains in plates due to the detonation of buried mines.

Jan 1, 2004

By J. -P. Tshibangu, E. Lefebvre

ABSTRACT : The Tournai’s region in Belgium is characterized by outcrops of limestone that were mined out long ago by different companies for cement and crushed materials. The region is densely populated and the vibrations generated by blasts in the quarries are of big concern. The occurrence of electronic detonators and development of computer sciences brought a new expectation in controlling the vibration level and, hence, carry out bigger blast operations. In this paper we present the results of two experimental blast programs that have been carried out by the Nobel explosive Belgium Company on the Gaurain-Ramecroix quarry to understand the effect of the delay on the vibrations generated in the neighborhood. The first program has been implemented during the early use of electronic caps in Belgium (1996) by performing some unit shots. An attempt to model the effect of the production blasts by the hybrid method (Hinzen 1988) gave promising but poor results compared to infield measurements. A new program (more than ten blasts) has been implemented in 2006 in which the delay and blast firing sequence (i.e. the order in firing adjacent holes in a row) have been changed; a new attempt is made to build unit signals by deconvolution and then try to model production ones. A comparison of the two approaches is made.

Jan 1, 2008

By Jason Rock, Rob Thompson, Lee Julian

Reactive ground is ground that undergoes a spontaneous exothermic reaction after it comes into contact with nitrates. This is commonly caused by inert rock hosting sulphide minerals, such as pyrites that act as the reagent. The presence and subsequent rate of reaction with nitrate based bulk explosives can be difficult to predict. Once identified, only explosives that are tested and proven to be compatible with the reactive ground may only be used. These typically take the form of inhibited ammonium nitrate emulsion blended with a limited volume of ANFO or porous prilled ammonium nitrate (PPAN) to ensure that all AN prills in the blend are wholly encapsulated and thus protected from the reactive ground. The requirement for high emulsion content bulk products limits the suite of products available for use to high energy, and high expense products. Further, if chemically sensitised products are used, charged holes must be left unstemmed to allow for gassing to occur, adding delay and exposing the blast crew to an unconfined charge in reactive ground. A range of inhibited products has been developed that are solid sensitised and can be bulked to as low as 0.9 g/cc (56.2 lb/ft3). The use of a solid sensitiser enables stemming to occur immediately after each hole is charged, confining any unplanned detonation more safely within the rock mass. The effective and precise manufacture of bulked inhibited products required a new and innovative Mobile Processing Unit (MPU) design. This MPU required the ability to blend two solid raw materials (AN prill & sensitiser) along with two liquid ingredients (AN emulsion and process fuel). This MPU has been designed, manufactured and has used successfully to manufacture low density inhibited explosives. This paper presents an innovative shift in inhibited bulk products with specific reference to their manufacture and application.

By Andrew F. McKown

Overbreak and damage to rock walls at the perimeter of rock excavation can lead to safety problems due to rock falls and additional costs due to a] extra mucking, b] extra concrete or shotcrete to backfill overbreak, c] additional rock reinforcement, d] additional water inflow and e] additional maintenance of rock walls. To minimize these undesirable effects, there are several perimeter control techniques available (i.e. line drilling, cushion blasting, pre-splitting, smooth blasting, and fracture control blasting) which control perimeter hole spacing, burden and loading to provide a smooth, stable excavation contour. Conventional perimeter control loading and hole spacing is satisfactory for massive, homogeneous formations, but when blasting in weathered or fractured rock closer spacing and very light loading is required.

Jan 1, 1984

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

The mining and oil industries employ techniques such as geologic mapping, core drilling and electromagnetic field techniques to explore for new deposits. New discoveries of major near-surface ore bodies are becoming progressively rare and traditional exploration methods are unable to resolve ore bodies deeper than about 500 m (1640.4 ft). Consequently high-resolution seismic reflection techniques show great potential for exploration to much greater depths down to almost 3 km (1.9 mi).

Jan 1, 2013

By Kevin Phelps, Jason Baird, Philip Mulligan, Dominique Nolan

The basic metric for linear shaped charge performance is the amount of cutting distance that the charge can effectively yield given a specific standoff and target. Due to its size and restricted production runs the 10,500 grain/foot (2,232.25 grams/meter) linear shaped charge has had only limited studies that examine cutting performance and standoff. This article covers research regarding cutting performance verses standoff as the charge is applied to common structural steel. Specifically this study uses A36 mild carbon structural steel blocks of 10.16 cm by 11.80 cm by 35.56 cm and standoff distances of 0.5, 1.0, 1.5, and 2.0 charge diameters. Data presented includes the presentation of actual cutting performance numbers, comparison of that data to projected performance based on currently recognized industry guidelines, and a discussion of what may contribute to the performance found in this study.

Jan 1, 2013