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By Michael Wieland

Work-principle computations for explosions underwater or in rock reveal the way the thermodynamic characteristics of surrounding material influence the resulting shock and heave. To reach total thermodynamic equilibrium under such transitory dynamic circumstances, reactions must quickly readjust to changing circumstances, which works for molecular (military) explosives where the fuel and oxidizer type atoms are originally in close proximity. For non-molecular mixtures with their dispersed zones of oxidizer or fuel, in particle or droplet form, there are numerous unproductive collisions, increasing the wait time required to reach chemical equilibrium. Underwater test data for molecular explosives compare rather well with the shock and heave resolved from the work-principal model, while the non-molecular explosives normally used in mining tend to yield a noticeable discrepancy. Years ago, it was recognized that the underwater shock was lower than expected and the heave was higher than expected for ammonium nitrate fuel oil (ANFO), though their resultant sum for the total work was roughly what was expected. When the readjustment of thermodynamic equilibrium warrants quicker chemistry than occurs in underwater or rock shooting, the time-retarded chemistry reduces the shock and raises the heave within the surrounding material without reducing the total work, unless the reaction retardation is quite severe. This technical complication in reality is a nonequilibrium issue that is difficult to resolve with just thermodynamics, though a rational set of transformation factors is formulated herein to represent those circumstances.

Jan 1, 2008

By Ravi Sahu, Ankit Jha, Sudarshan Rajagopal, Purushotham Tukkaraja

Geologic structures are one of the crucial parameters in blast design. Structural geology and rock properties influence drilling patterns, blast layout, and initiation systems. A comprehensive understanding of structural characteristics is essential to achieve the desired blasting objectives. This paper aims to identify geologic features in a bench using images obtained from the drone.

Feb 1, 2020

By Emily Johnson, Catherine Johnson, Rachel Bauer, Paul Pitzel

Demolition projects involving explosives may incorporate cutting charges to sever columns in collaboration with kicker charges that “move” the columns out of alignment. Traditional kicker charges often involve the use of dynamite secured to the column above the cutting charge. Nitroglycerine, the main component of dynamite, causes medical problems and can be a hazard to workers on site. Dynamite can also cause fragmentation of the column and structures, resulting in potential injuries to people or leading to the possibility of cutoffs in neighboring charges. This study investigates the use of water-cased kicker charges to reduce the amount of dynamite in demolition. Water charges, traditional charges, and detonating cord charges were placed on hanging steel columns and analyzed for the fragmentation of the column and velocity of the column. A W 10 X 22 beam was hung in an underground limestone test area and allowed to swing freely acting as a severed column. Charges were attached to the bottom of the column with tape and initiated using electric detonators. Explosive charges of dynamite or detonating cord were placed in the center of a water container or directly on the column for use as the kicker charge. Tests were recorded with high-speed video and velocity was calculated using Phantom Camera Control software. Velocity and time were then used to calculate force, kinetic energy, impulse, and pressure exerted by the explosive on the column. The water charge transferred energy to the column over a larger area with no direct contact of explosive and the column. Water charges moved the column faster and with more power than traditional charges. After preliminary tests, water charges were also used as the primary kicker charges in a full-scale demolition project as a case study using 118 charges. The kicker charges successfully moved building members without creating fragmentation while using less dynamite than traditional kicker charges. Due to the success, multiple full-scale projects are being designed using water charges to show success and repeatability.

Feb 6, 2023

By Jerry W. Schweiker

An extensive computer program has been developed which will store and analyze pertinent blast related parameters such as date, time, shot coordinates, charge, delay times, etc. In conjunction with these blast parameters, measured ground vibration information can be stored. In addition to actual seismograph data, predicted ground vibration in terms of velocity (inches/sec) can be generated for selected receiver locations. The magnitude of the blast generated ground vibration is based on scale distance relationships. The program can be used for planning blasts, to satisfy local environmental regulations and for insurance and/or legal purposes.

Jan 1, 1984

Blasting in a development heading or breasting operations starts from a cut. The void created by the cut provides a free face for the remainder of the round. It is the most critical part of the round because the later firing charges cannot pull to the desired depth unless the cut comes out as planned. The Burn cut is most commonly used in Canadian mines.

Jan 1, 1995

By Zoltan Susanszky

The total available energy in an explosive charge is seldom fully utilized in industrial operations. For this reason more explosive is normally used to perform a job than we would calculate. In an explosive detonation some energy is generated as waste energy which can not be efficiently used. This results in added expense and possible environmental damage. This waste energy can create problems in metal forming with explosives and during commercial underwater blasting operations.

Jan 1, 1976

By Leslie C. Taylor, Scott A. Yamada, William L. Fourney

Previous studies have shown that the pressure load on a target by a buried explosive charge is not smoothly distributed. The effort reported here was undertaken to explore the mechanisms believed to cause this uneven pressure distribution: jets from the surface originating in instabilities caused by the explosive shockwave interacting with surface irregularities. Small-scale tests using conical, hemispherical, and cylindrical indentations in the sand surface above a buried charge were conducted to identify trends in the velocity and form of the resulting jets. In these tests, the most important factor affecting the resulting jets was the distance between the bottom of the indentation and the top of the charge. Cylindrical indentations resulted in higher jet velocities than those from comparable hemispherical and conical indentations.

Jan 1, 2012

By Richard A. Dick

Few topics in the blasting industry are more controversial than the proper riming procedure for large-diameter ammonium nitrate-fuel oil (AN-FO) charges, despite the considerable amount of research that has been done both in the laboratory and in the field. The January, April, and June 1975 issues of Emphasis on Blasting contain interesting discussions on priming (5). An ideal primer is one that will surely and efficiently initiate the AN-FO column at the correct location to assure optimum blasting performance. During the 20 years of AN-FO's existence, singlepoint priming, axial priming, multiple-point priming, thermal priming, and shock riming have all been advocated as the "optimum" method. This is not surprising because blasting specialists have often differed on even the most fundamental concepts. To define the optimum primer, we must know what detonation characteristics in the AN-FO column are most desirable. Again, authorities disagree. This paper will discuss conclusions of various studies in an attempt to clear up some of the confusion.

Jan 1, 1976

By Karl Ingmarsson

A model for drilling productivity and total drilling cost is presented. It specifically addresses down-thehole drilling, but also covers other drilling methods. The important factors are: 1, productivity in tons drilled; and 2, total cost per drill ton. For non-blasthole applications these factors are measured in drill feet and cost per foot. The model focuses on the entire system and allows the operator to optimize the system based on individual drilling conditions.

Jan 1, 1998

By Roger L. Keller

This paper covers the design and test blast procedures for several drop shafts and edits leading to the completion of a recent Rochester Pure Waters Expansion Project . Due to the projects "in-town" presence, and its close proximity to many sensitive vibration sites, very stringent ground vibration limitations and guidelines for blasting were places on each site.

Jan 1, 1991

By Robert C. Fouchard, Gordon Chalmers, David E. G. Jones, Ivana Alilovic, Phillip D. Lightfoot

There have been numerous international instances over the last several years in which pumping emulsion explosives has resulted in accidents, apparently as a result of increased thermal sensitivity under these conditions. The key questions for the explosive industry are (1) what are the parameters that influence the sensitivity of emulsion explosives and, (2) how do these various parameters interact. To address the sensitivity of emulsion explosives to various parameters, a study was undertaken using an accelerating rate calorimeter (ARC) and a heat flux calorimeter (HFC). The effects ofthe addition of ammonium nitrate (AN) prills and different grades of aluminum (Al) on the thermal behaviour of emulsion explosives were determined. Additionally, changes in pressure, atmosphere (inert or oxidizing) and sample vessel material were assessed for their impact on thermal sensitivity. Addition of AN prills, fine granular Al or atomized Al did not affect the onset temperature for exothermic decomposition, so that the maximum “safe” temperatures for emulsions containing these additives will be similar. There were differences in the rates of self heating, however: AN prills decreased the rate of self heating, whereas atomized Al increased it. The emulsion formulations containing atomized Al produced small holes in titanium vessels. This phenomenon did not occur in Hastelloy C vessels, providing a reminder that materials of construction need to be carefully considered for equipment used to manufacture or handle emulsion explosives.. Both ARC and HFC experiments gave lower onset temperatures in air than in argon. We attribute this to oxidation of the oil phase by air. This result is significant for dry-running pumping conditions, where emulsion is heated in the presence of excess air.

Jan 1, 2000

By Allan King

Ammonium Nitrate (AN) is most commonly encountered as either a prilled solid or a highly concentrated aqueous solution, with or without organic ( e.g amine) nitrates. Under certain conditions of fire exposure involving prilled or solid AN, the molten state can be formed. The shock sensitivity of the molten material at temperatures greater than 220 Celsius has been found to be much higher than that of the prilled or solid form. Molten AN can be a precursor to events leading up to explosion of a bulk prill storage pile as a result of fire exposure. The explosion hazards presented by molten AN are a function of two factors; 1) its shock sensitivity and the deflagration to detonation ( DDT ) properties of the molten material, and: 2) the ability of large masses of unfueled prilled AN to be initiated and detonate. This paper presents the results of tests designed to determine the shock initiation and DDT properties of the solid ( prilled ) and molten AN.

Jan 1, 2008

By Gimtong Teowee

SDI has launched the Electronic Detonator Blasting System containing a set of robust serial protocol and hardware exhibiting great ease in field usability and deployment. Programmable delay time with increments of 1 ms up to 10s is possible with excellent timing accuracy. Bus length of up to 2 km containing 1600 EIMs can be employed. A key feature of the SDI Electronic Blasting System has been its high tolerance towards current leakage in the bus line.

Jan 1, 2007

By Yessica Idrogo, Omar Gómez, Francisco Pérez, Eduardo Yrigoyen

Rock blasting is one of the most important operations in the mining cycle value chain, requiring optimized explosives mixtures to get good results. A new and better strategy, and that which is discussed herein, is to design a new emulsion explosive, which can provide improved characteristics and benefits over and above general types of emulsion explosives. It is therefore critical that this product is functional over a wide range of conditions

Jan 1, 2019

By W. Fourney

In the late 70’s and early 80’s in conjunction with other oil and gas well stimulation studies, personnel from the Dynamic Effects Lab performed model testing to demonstrate the effectiveness of utilizing an open section of borehole just before a plug. We called the process stem induced fracturing. The open section beneath the stem was used to increase the pressure magnitude and spread out the duration of the pressure pulse. This technique was later utilized to by Frank Chiapetta (1) in the fracture and fragmentation of rock in quarry blasting situations. He called his technique air deck blasting. In fact, Frank found that the Russians had previously discovered the same technique. There is currently interest in utilizing air deck blasting with an open section of hole beneath the explosive at the bottom of the bore hole to better remove the toe in a fragmentation shot. This paper reviews the development of stem induced fracturing and then describes a series of model tests conducted to measure borehole pressure at points along a borehole when an explosive charge is detonated at the midpoint of the borehole. Tests were conducted in both stiff boreholes (aluminum) and less rigid boreholes (PMMA-Plexiglas). Pressure time profiles were measured at the charge site, midway between the charge and the bottom of the hole, at the stemming at the top of the borehole, and at the bottom of the borehole. Crack initiation sites and crack propagation were also determined in the PMMA models. Some high speed pictures were taken of the event in the PMMA.

Jan 1, 2006

By Per-Anders Persson

TIGERWIN, now on CD, is a user-friendly personal computer code (running under Windows) which determines the detonation and expansion state of an explosive from its known chemical composition. TIGERWIN is intended for users in the mining and commercial explosives industry who do not routinely program or run Fortran codes. The code allows the user to open a window on the computer screen and enter the initial density and the weight percentage composition of an explosive, ingredient by ingredient. Alternatively, the code can balance the composition with one or more ingredient percentages fixed, while proportionally adjusting the others automatically to give a total of 100%. The equation of state and its parameters can be user-selected from several proven and tested versions of the BKW, the JCZ, and the ideal gas equations of state. TIGERWIN allows the user to select several options for different additional calculations, such as determining the constant volume explosion, the Chapman-Jouguet (C-J) point, the detonation Hugoniot, the expansion isentrope from the C-J point, and point calculations with selectable specific volume and temperature. Additional options include calculations of detonation data with one or more ingredients partially reacted, assuming either temperature equilibrium between reaction products and unreacted material, or keeping the unreacted material “cold” at the initial temperature. Thus the code can run both ideal and non-ideal detonation calculations. The code automatically saves the input and output files in a separate directory for future reference. The output from several calculations can be displayed and printed in the form of a comparison table. In it, the key results of up to five calculations with different explosive compositions can be compared. The results from an individual calculation can be displayed graphically and printed with expansion work, pressure, or temperature as functions of specific volume. A complete listing of the details of the calculation results, similar to those from the original Fortran Tiger calculations, can also be displayed and printed. No computer experience is required to run the code and workshop participants are encouraged to bring in their own formulations to try out on TIGERWIN

Jan 1, 2000

By Brad Johnson

Homestake Mining Corporations' open cut operation at Lead SD. experienced a highwall failure in October of 1993. The failure released a 75' section of rock wall at the 5280' level. It came to rest on the 5200' safety bench. Since work was in progress below the failure, this rock had to be removed for safety.

Jan 1, 1995

By John R. Schuring, Walter Konon

The 2.0 in./sec. peak particle velocity criterion traditionally used to protect structures from blast induced vibration damage is non-conservative for landmark structures. Various factors which must be considered in establishing vibration criteria for landmark structures are discussed. Existing criteria by past investigators for this class of structure are presented.

Jan 1, 1984

By Isaac E. "Chip" Harris

Any contractor who agrees to supply materials or to perform services for a sum, is well aware of the importance of proper pre-bid information. Being able to properly plan costs and methods results in profits that allow the contractor to prosper. The paper discusses procedures used in estimating pre-bid cost; in particular, drilling and blasting cost for highways, dams and general construction projects. It breaks cost down into five categories and relates them to a total estimate used in bidding and budgeting a construction project.

Jan 1, 1975

By Dieter Froelich, Giles Turcotte

In the near future, Bong Mining Company (BMC) will start mining a new deposit known as Zaweah II which is a narrow iron orebody requiring multiple row blasts with the bench floor as a free face. This called for the development of a new blasting technique. The article delineates the problem and its restrictions related to blasting. It also describes the approach which was taken for developing this new blasting technique which is essentially an application of the cratering theory with near spherical charges. Basic crater tests were conducted using various combinations of hole sizes, explosive strengths and delay patterns. From the results obtained, several alternatives were considered for production blasts and the most promising ones were evaluated.

Jan 1, 1980