Search Documents

By Miles Huntly

This paper will discuss the ideas and actions that led to the development of a Drill Improvement Team at an open cut coal mine in Australia. It will show significant cost savings can be attained by forming a focused Team derived from all the participants that go into drilling a blast hole

Jan 1, 1999

By John Eloranta

This paper is a case study showing the assembly of available rock property parameters for the purpose of blast design. Blast optimization now includes subsequent milling and requires a full knowledge of the rock mass. Individual blast holes should be designed using all available data. The parameters include: geologic layer from diamond drilling, shovel performance, crushing plant experience from that area, drill monitoring, magnetic susceptibility from a downhole probe, size analysis history from digital image analysis, compressive strength tests of problem areas and cross hole sonic testing. Bedding thickness observed from drill core appear to have a strong influence on fragmentation.

Jan 1, 1996

By D T. Froedge

The state of Kentucky is making some changes in it's blasting program namely instituting a training program for blasters and instituting a new classification of blaster titled "Class A Kentucky Blaster". These changes will take place within the next year and are felt to be of great interest and benefit to those in the blasting industry.

Jan 1, 1978

By M Oldenburg, P J. Digby, L Nilsson

A constitutive model for the simulation of fracture and fragmentation processes in rapidly loaded rocks is studied. The model was included in a wave propagation finite element code. The results obtained from two different configurations of explosive charge and reflecting surfaces in a plane strain problem were studied. The evolution of the time-dependent fracture pattern is presented.

Jan 1, 1985

By John C. Brulia

Blasting is both an art and a science with the primary objectives being safety and performance. Safety, the paramount objective, is a process that has limitless opportunities for improvement. Quality, a concept espoused by world-class corporations to competitively meet the needs of customers for goods and services, can be adapted to the explosives industry to improve blasting safety.

Jan 1, 1993

By Larry Mirabelli, Gerard J. O'Brien

"The construction of the Third Harbor Tunnel is a key element of the Central Artery TunnelProject. The tunnel is to traverse Boston Harbor directly linking South Boston to EastBoston. The tunnel is a cut and cover tunnel as opposed to a bored tunnel. The cutdimensions are 95' wide, 110' deep and approximately 4000' in overall length."

Jan 1, 1993

By Guang-Xin Li, Rui-Ping Guo

Based on the analysis of factors affecting the cracking performance of Silently Cracking Agent (SCA), a new SCA structural model is built and a study on the swelling mechanism of SCA and a method to increase swelling thrust by adding the swelling agent are presented. The reason for blow-out and the theory for avoiding blow-out are put forward. The new model improves the SCA theory and provides new method for developing effective SCA. Based on experiments made in laboratory, two types of SCA are developed. A Temperature Control Meter (TCM) has been developed to solve the alltemperature- crack problem after studying the suitable temperature scope of SCA.

Jan 1, 2000

By Larry R. Fletcher, Virgil J. Stachural, Matthew N. Plis

The Bureau of Mines is conducting research on blasting methods that reduce highwall overbreak and the associated rockfall hazards. This paper presents the results of a series of tests to improve presplitting at a western surface coal mine. Reductions in overbreak were achieved by decoupling and/or repositioning the main explosive charge in the 10-5/8 inch presplit blastholes that formed the highwall. Blast designs are presented by the authors for 1) repositioning the explosive charge from a weak rock layer to a stronger rock layer, 2) decoupling with cardboard tubes in the toe region, and 3) suspending bagged powder at intervals along the length of the blasthole. About the same total quantity of explosives was used in all three test designs. It was readily apparent from periodic visual examination and photographic surveys of the highwalls that the amount of rockfall was reduced, and with a longer delay before rockfalls began, in all test areas.

Jan 1, 1991

By William Clark, Rick Taylor

"Ajax Contracting was awarded the project to drill, blast and crush 100,000 tons of quarryrock for the Forest Service In Elk City, Idaho, during the summer of 1992. This projecttakes place in an area where environmental groups opposing any development in NorthernIdaho forced the Forest Service to look for road rock In any place they could get it. Theresult was that a quarry could not be developed. It was decided that rock would be takenfrom a road cut (under the guise of straightening the road) on the main artery of Elk City,Idaho making the drilling and blasting a very sensitive issue to the local truckers haulingtrees and lumber to and from a mill."

Jan 1, 1993

By James Camp

"During the 1950's a cement plant was rebuilt along a Missouri River bluff. The escarpmentwas composed of inter_bedded shale and limestone, typical to western Missouri. All of theraw materials needed to produce cement had been mined via room and pillar at the plantsite since the late 1800's. Portions of the mine began to fail in the late 60's., and by the mid70's M.S.H.A. declared all the areas where the lower Winterset limestone had beenremoved from the back to be ""unsafe"". M.S.H.A. explained that no work could beperformed in or above these unsafe areas unless the work itself was to render the area safe."

Jan 1, 1993

By F Hunyadi

The seismic effects resulting from blasting are still a problem today although a great deal of research has been conducted in this field. A great amount of data defining the seismic effects can be collected with the proper instrumentation, however because of the difference in building materials, construction methods and foundations the characteristics of the seismic wave can not be directly correlated to the building response and possible damage.

Jan 1, 1975

By R Yang, P D. Katsabanis, W F. Bawden

Understanding the mechanisms which are taking place during the propagation of a stress wave generated by an explosive charge is of high importance in the detection, characterization and prediction of blast induced damage to the rock. Vibrations caused by the detonation of an explosive are suspected to contribute significantly to the extension of the damage zone. Vibration monitoring close to a blasthole is a relatively new field of research, the hindrance being the scarcity of transducers capable of sustaining extreme accelerations without damage. This paper focuses on the vibration monitoring aspect of a blast induced damage study; the experiment took place at Queen's test site and was meant to record near-field vibration as close as 1 m from 100 mm diameter blastholes.

Jan 1, 1993

By Pierre Mousset-Jones, Geraint W. Harris, Robert Karlin, Jaak Daemen

In order to minimize the ore dilution induced by blast movement in surface mines it is necessary to quantify such movement. This will make it possible to more accurately locate the grade boundaries on the surface of a blasted rockpile prior to excavation. This paper describes the development and testing of a method to accurately measure the direction and magnitude of sub-surface blast movement. The technique involves the use of magnetic "radiometry, using a cesium vapor "radiometer and real-time differentially corrected, GPS system, to locate the post-blast position of magnetically enhanced target objects, whose pre-blast locations are known, without disturbance of the blasted rock. The objective is to design an accurate and efficient technique which can be integrated into a mines production cycle.

Jan 1, 1997

By P. D. Lightfoot, C. Badeen, R. Turcotte, D. E. C. Jones

Following localized (i.e. hot-spot) ignition, there is a minimum pressure required for combustion to propagate in water-based commercial explosives. The latter is usually referred to as the ‘Minimum Burning Pressure’ (MBP) of the explosive. In the present work, both an apparatus based on hot-wire ignition and an associated methodology were developed to measure the MBP of water-based explosives. It was demonstrated that the MBP constitutes a sharp pressure threshold below which the probability of inducing sustained burning in these explosives becomes very small. It was found that each emulsion explosive tested has a distinct MBP value, which depends critically on its formulation. It appears that this test may offer a firm basis for the classification of emulsion explosives for regulatory purposes.

Jan 1, 2004

By Adrian J. Moore, Alan B. Richards, Rob Evans

Air and ground vibration from blasting is influenced by the delay pattern that is used. Wavefronts from blastholes fired in a blasting pattern can combine in certain circumstances to give increased blast vibration levels. A simple computer model has been developed which shows the combined effect of wavefronts from a multi-hole blast and identifies if wavefront reinforcement occurs, and permits delay patterns to be designed which will avoid or reduce wavefront reinforcement.

Jan 1, 1994

By Chad Ducey

The proper utilization of energy in an explosive column is of paramount importance to the success of any blast. Historically, Powder Factor (the weight of explosive per mass or volume of material to be blasted or its inverse), has dictated the blast design. The concept of Energy Factor is a more effective method to design a blast. In order to utilize explosives efficiently, the energy contained in any given product must be quantified. The Powder Factor method, although historically successful, assumes that a pound of cast pentolite affects the material to be blasted the same as a pound of ammonium nitrate / me1 oil (ANFO.) Years of experience and scientific testing have led the blaster in the field to believe otherwise. The next logical technological step is Energy Factor. The Energy Factor method that will be discussed in this paper takes into consideration not only the weight of the explosive, but also the weight strength (Cal/g) and the density (g/cc) to yield a constant relative Energy Factor. The result of such a method is a factor that can be used in the field exactly the same as Powder Factor, but that reflects the relative energy of any given product in terms that will reflect the relative cost benefit of that explosive selection. The Energy Factors associated with different available explosives make it possible to compare the difference in the amount of energy per loaded pound in each unit length of borehole. This paper will examine the concept of Energy Factor in an in depth manner and also compare this quantification method to that of Powder Factor. It will also demonstrate the value of using Energy Factor and how it can improve the efficiency of a blast design. The misconceptions that come along with using Powder Factor will be examined and comparisons will be made between boreholes loaded using Powder Factor and those that are loaded using Energy Factor. This paper will clearly define the differences between these blast design methods and allow the reader to realize the production, quality, and economic advantages of using the Energy Factor method.

Jan 1, 2000

By Deane Boddorff

A 440 Volt AC power line is a typical power source for energizing electric blasting cap circuits in driving hard rock tunnels. A common misconception exists that the caps actually see 440 Volts. This paper describes an analysis of the entire blasting circuit determining the current flowing and the voltage drops through each component. If, from such an analysis, one determines that the current to the caps is too low or too high, the components that require changing are easily recognized.

Jan 1, 1975

By Robert C. Friend

On-the-job and "hands-on" training programs which attempt to train newcomers to blasting with instructors whose only qualification is their experience can easily miss the boat. Organized training programs which utilize competent instructors and a well developed format are necessary if we wish to provide a meaningful program of instruction, But, let's not go overboard and attempt to provide a level of training which goes far beyond the scope of the worker's duties and responsibilities, and "need to know",

Jan 1, 1980

By Richard Dooley

The purpose of this paper is to give a description of a controlled blasting program and why Georgia Power now has one; mainly because of the Spillway Project.

Jan 1, 1981

By J J. Mullay, G W. Anderson, C J. McFinley, J F. VanNorman, C J. Kefer

Previous work has shown that testing of precompression effects conducted on a small scale under simulated field conditions in actual rock provides a reasonable model for the evaluation of explosives and initiators under the adverse conditions encountered in production blasting. Using this methodology can result in greater understanding of the phenomena as well as the ability to predict performance. This effort has been extended to evaluate various parameters not previously studied in a controlled fashion. The present paper describes the use of this technique to study the effects of delay timing on precompression effects. Intervals from 25 to 150 milliseconds are included in the study. Both VOD measurements and damage estimates are utilized in the evaluation. The results demonstrate that timing delay between holes is quite important in determining the overall effectiveness of a blasting program.

Jan 1, 1994