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By Don Thompson

The Minntac Mine drills and blasts approximately 75 million long tons of taconite per year. This requires drilling one million feet of 1 6-inch diameter holes. We are in the process of replacing our old generation rotary blasthole drills (Gardner-Denver 120's and Bucyrus-Erie 61R's) with new generation rotary blasthole drills (Bucyrus-Erie 59R's and P&H 120A's).

Jan 1, 1998

By Michael Karmis, Syed Muhammad Tariq, Zeshan Hyder

This paper analyzes the blast design for lime stone quarries of two major cement plants in Pakistan. The production blast of these quarries was resulting in excessive boulders production. At some instances, the rate of boulders production was approximately 10%-15% of the main production blast i.e. if a round of main blast gave around 4000 tons of material; almost 400 to 500 tons of that material was in the shape of massive boulders. This gave rise to increased operating costs requiring boulders collection, drilling and secondary blast.

Jan 1, 2012

By Paul Schmiesing, Matt Higgins

Central Oregon is a fast growing resort community centered in Bend, Oregon. Bend is bordered by the Cascade Mountains to the west and the high dessert to the east. Central Oregon is blanketed with lava rock with little topsoil. Ditch blasting is a staple in the area. Almost all utilities excavation (gas lines, sewer lines, water lines, and electrical lines) requires blasting. There is also a considerable amount of blasting required for site excavations and drywells. On average, there are over 500 blasts per year in Bend alone. All of this blasting is done using small holes, generally 2.5 inches in diameter. Typical ditches will have 200 holes, between 2-3 rows wide, with an average depth of 8 feet, and on 36 inch centers. Almost all shots are dry. Successful blasting requires careful control of drilling and loading. The vesicular basalt contains numerous lava tubes and caves making drilling and loading difficult. The rock conditions vary greatly from one side of town to the other requiring different powder factors and different scale of distances for vibration control. Caret%1 calculations of vibration predictions and use of site-specific seismic info is necessary. Marry shots will require deck loading and careful timing to ensure one-charge per delay. It is an every day occurrence to be blasting near residential and commercial structures or high pressure gas lines. Many times ditch blasting will incorporate excavation blasting. The different hole patterns used for the ditches and the excavation shots presents challenging timing sequences.

Jan 1, 2000

By Ethan Steward, Robert Eades, Kyle Perry

Shock tubes, either gas or explosively driven, are often used for physical modeling of free field explosions or arena testing. The use of shock tubes often requires less setup time of subjects and smaller driving forces to create pressure versus time waveforms similar to that of arena testing. However, the effects of the shock tube cross sectional geometry on waveform properties is uncertain while free field explosion wave propagation and estimation is well studied.

Jan 1, 2018

By Jack Eloranta

Building on previous work, this paper expands the template for modeling the economic relationship between blasting and grinding. The actual efficacy of various blasting enhancements is not addressed, however, placing costs and potential benefits in proper context should aid in designing mine/mill optimization trials.

Jan 1, 2014

By William Reisz

Managing the blast site at almost any operation can be a daunting task. There are so many details that must be observed, understood, and acted upon. It goes without saying that there are no two locations that have the exact same challenges and concerns. The level and the extent of these challenges can vary widely.

Jan 1, 2014

By Finn Ouchterlony, Gert Bjarnholt, Robert Holmberg

A system for contour blasting with a linear shape charge principle has been studied /10/. In one operation the charge creates two notches along the bore hole wall and breaks the rock mass. The built in notching capability makes it possible to reduce the specific charge and the bore hole pressure to 1/3 of what is used in conventional contour blasting and to ensure that cracks are initiated and propagated only at the notches and nowhere else. The notching capability of linear shape charges has been studied experimentally and the bore hole pressure calculated to aid in optimization of a charge for future field experiments in bore holes with a diameter of about 50 mm.

Jan 1, 1983

By Josephine Bones, Robb Larson, Daniel Miler

Avalanches are commonly mitigated through the use of explosives at ski resorts and above transportation corridors. Surprisingly, very little research has been conducted on snowpack response to explosive inputs, and efforts to model this response have been limited. The purpose of this ongoing research project is to ascertain an understanding of the dynamic snowpack response in relation to explosive size and height above the snowpack, coupled with snow conditions, to enhance avalanche control. A system of sensors and computer-controlled data acquisition components has been created to record the movement of snow resulting from the charge detonation. The system records acceleration vertically and radially within the snowpack at two distances from the point of detonation as well as blast air pressure at one location during explosive events. The data at two locations allows inferences to be made about the transmittance and attenuation of shock waves through the snowpack radially as well as vertically. The data shows that raising charges above the surface results in increased snowpack dynamic response when compared to surface detonations. Applying power function regression to accelerations for individual charge elevations, it was determined that both radial and vertical rates of attenuation were not dependant on charge elevation. Additionally, raising the charge also resulted in increased dynamic response at depth within the snowpack

Jan 1, 2012

By Yu Yalun, He Jun

Wavelet Analysis is very effective for processing the high-varying signals by its good localization properties. We studied its feasibility of application in the field of blasting seismic signals processing, found the basic representation wavelet for blasting seismic signals analysis, and analyzed a concrete engineering example with analyzing wavelet.

Jan 1, 1997

By William Reisz

The explosives and blasting industry has a commendable safety and security record, especially over the last several decades. This is due in large part to our newer technologies, better training and education, engineering practices, corporate initiatives, our professional organizations, and whether we like to admit it or not - our regulatory agencies.

Jan 1, 2012

By Thomas L. Barkley

This paper describes an unusual design for a 12 foot diameter, 30 foot deep circular shaft shot in a close in urban environment less than 100 feet from occupied structures. It uses diagrams, video footage, and vibration results to describe a 3 deck, 17 hole burn round used to pull 17 feet in one lift.

Jan 1, 1994

By Ashwani Jain, D K. Soni

Compressive strength of rocks is often required by mining engineers and quarrying authorities for blasting operations. Uniaxial compressive strength of rocks can be predicted with reasonable accuracy with the help of point load strength tests which can be easily conducted at site by the field staff, simultaneously as the cores are recovered from drilling operations. A number of diametral point load tests and uniaxial compressive strength tests have been conducted on the specimens of different rock types under air dried, and saturated condition as well to study the effect of ground water saturation on strength. It has been observed that due to saturation uniaxial compressive strength and point load strength get reduced to a maximum of 32 and 29 per cent respectively. It has also been observed that uniaxial strength is sixteen times the point load strength in air dried as well as saturated condition. However, this factor used for calculating uniaxial compressive strength may be reduced to a lower value for the safety of miners in field blasting operations.

Jan 1, 1994

By Lon D. Santis

This paper reports on an evaluation of the safety characteristics of short lead, 5 centimeter (cm), Magnadet1 detonators. The Magnadet initiation system uses magnetic induction principles to transfer electric energy from the firing line to the detonator without a physical connection. This study was initiated because the Magnadet initiation system represents a new technology and the Bureau is interested in ensuring that no potential safety hazards are introduced into the nation's mining environment. The Magnadet system and its proper use are described along with a discussion of how it works. The potential hazards examined are: stray current from mine service power, lightning, DC current, static electricity, and radio frequency transmissions. Tip strength is also evaluated. Experiments were conducted to evaluate some hazards and theoretical methods were used to evaluate others. The results showed that the Magnadet short lead initiation system does not exhibit any unusual safety hazards. The new system is at least six times as resistant to common hazards as currently used electric initiation systems, so long as the insulation is intact.

Jan 1, 1992

By Tristan Worsey, Nathan Rouse, Daykin Schnell

The authors were retained by a proposed underground metals mine operation to evaluate the potential blast vibration amplitudes that could be generated at surface structures above the proposed mine. Literature reviews of published blasting documentation gave little information, data, or models on surface blast vibrations produced by underground mines. At the client’s request, the authors contacted a number of underground mining operations to evaluate interest in sharing blast vibration data with the authors so that the authors could develop an underground-to-surface blast vibration regression equation. The authors worked with three underground metals mining operations to collect surface blast vibration data produced by heading blasts and stope blasts. The data included blast vibration amplitude values, seismograph records, blast design geometry, charge weights, and detonator delay and sequence designs. The total amount of information was used to produce a regression equation and summary dataset that could be used by the proposed underground mining operation to evaluate blast vibration amplitudes that will be generated on the surface. This work is published and presented so that operations with proposed underground mines or proposed underground mine extensions can use these equations to predict vibration amplitudes on the surface above the mine workings before any blasting occurs.

By David Davison, Richard Johnson

Metal-oxidant blends are ordinarily unsuitable as diiect replacements for explosives, because the reaction occurs too slowly. Oxide coatings protect metals, preventing or delaying reaction. By contrast, the electrically-activated reactive composites described below are configured as metal fibers or foils in close proximity to oxidants, with continuous electrical paths from one end to the other. By quickly vaporizing the metal component with an electrical pulse, a reactive composite will be activated, and the reaction will occur rapidly.

Jan 1, 1999

By Kim Henley, Chris Batten

This paper discusses the use of the Orica WildFireTM flyrock model to help mining operations in Australia and Asia minimise blast exclusion zones for equipment, increasing utilisation and productivity and delivering downstream value

Feb 1, 2020

By Charles Joyce, William C. Burkle, Dan Murphy

Rare indeed has a major cross country natural gas pipeline met and surmounted such obstacles as the Iroquois Gas Transmission Line from Canada to Long Island, New York. Of the 370 miles long length a fair estimate has been that 1/3 or 122 miles were across rock country. Spread One, Four and Five were particularly difficult. If is estimated that over 75% of the required blasting was on those three spreads. The term "spread" goes back to the old term of describing a ranch.

Jan 1, 1992

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 R Mancini, G Borla

This paper analyses the first results of a part of an EEC research project ("Blasting control for underground mining"). This research that involves three universities (Paris, Torino and Leoben) has been carried out at the Eisenerz test mine in Austria. In the experimental campaign here reviewed, parallel holes rounds have been fired "decomposed", which means with enough delay between the explosions of the successive blastholes groups to allow for a separate evaluation of their effects on the rock. The seismic effects have been recorded by geophones placed at small distance from the blast, the aim being to find out correlations between the features of the seismogram and the good or poor performance of the single blastholes, or of the groups pertaining to the same delay. Indeed, the seismogram is the only safe and cheaply obtainable description of what happens during the blast. The seismogram should be transformed in a diagnostic tool in the round 'calibration' stage, and in a routine control device during excavation.

Jan 1, 1995

By A N: Zditovetsky Shishov, M G. Menzhulin

At present in a building industry demand for products from granite, gabbro and other rocks, steady to erosion, natural and chemical weathering, was essentially increased. It has caused the enlargement of exploitation of stone block deposits and necessity of creation of new technologies of hard stone cut.

Jan 1, 1996