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By R. J. Cefalo

Blast and mining spillover between phases or critical areas of the pit is a continuing problem in the mining industry and a safety concern for operating mines. The challenge for many mines is to produce the highest value in the shortest amount of time for any project. For any project, the top priority of any mine is producing ore as fast as possible. The next challenge is to keep that ore feed continuous. To achieve continuous ore feed, pits are designed with multiple phases that are connected and are mined at different elevations. This difference in elevation causes dangers with spillover between the phases during mining, drilling, and blasting. This paper covers an incident that occurred at an active mine and the work completed in creating a spillover control program over an active mining phase. The drill and blast technical group was responsible for creating blast patterns to reduce spillover between these phases. Unrealistic goals and expectations were initially set for the area of the pit. The drill and blast technical group needed to figure blast objectives and work with the geotechnical team to align with these goals. This paper will go over the executed example of setting up spillover targets and expectations for multiple sections of an operating mine. Different sections of the pit had different control measures and blast objectives due to narrow laybacks and double benching. The use and value of blast objectives and goals were beneficial in setting expectations and measuring design success. Having unrealistic blast goals can set up the operations to fail or get frustrated in trying to work on an impossible task. The problems and risks of phase interactions for many open pit operations need to be considered in the design process, along with designed controls that minimize the probability of any safety incident. Mine designs are being created in the industry and do not consider phase-to-phase mining interaction and the impact it would have on safety or production. The best future for safer mines is blast patterns that reduce spillover between phases of mining and pit designs that might account for spillover interaction.

Jan 1, 2024

By Thierry Bernard, J. M. Laboz

2000 HIGH-TECH SEMINAR Blasting Technology, Instrumentation and Explosives Applications

Jan 1, 2000

By Cathy Aimone-Martin, Caitlin Woznick, Brent Meins

This study is a continuation of previous work in which the responses of tall structures to close-in construction blasting at two rock excavation sites are evaluated. A total of eight buildings were instrumented to calculate blast-induced wall strains. Of these structures, five high-rise buildings measuring 166 ft (51 m) to 294 ft (90 m) in height (15 to 24 stories), were included for this study and compared with the results of previous studies that included one to three story residential structures and mid-rise structures (four to six stories). All five structures were built between 1908 and 1940 with interior walls comprising aged plaster. Three of the structures are designated Landmark, subject to a 0.5 in/s (12.7 mm/s) regulated peak particle velocity (PPV) limit. The regulated PPV limit for the two other structures was 2.0 in/s (50.8 mm/s). To date, a total of 450 close-in construction blasts have taken place over six months at the two adjacent projects, blasting three to six times per day at each site. Seismograph instrumentation included tri-axial geophones in the ground and bi-axial geophones (horizontal components only) mounted on structure exteriors at the corners closest to blasting. Peak global wall tensile strains were calculated from time-correlated differential structure displacements in two horizontal directions as measured by upper and lower geophones mounted near the roof and at street levels. Wall strains were correlated with ground excitations to establish a stiffness factor for each structure defined as the upper bound linear regression slope for strain as a function of ground displacement. In addition, a structure-specific regression best-fit function was established to relate horizontal components of displacement to velocity. These two functions were used to determine the maximum ground motion velocity for a desired limit placed on wall strain. A 25 ?-strain limit was suggested for both projects to protect interior plaster walls. To date, global wall strains have not exceeded 0.53 ?-strains (or 47 times the project limit) for peak particle velocities up to 3.49 in/s (88.6 mm/s). This demonstrates the low strain response of tall structures to ground velocities well above regulated limits. The stiffness factor computed for the most flexible high-rise building was 688 in-1 (17475 mm-1). In comparison, stiffness factors for the most flexible residential and mid-rise structures previously studied were 8651 in-1 (219735 mm-1) and 4387 in-1 (111430 mm-1), respectively. Based on a large number of measurements made at these study structures, the maximum horizontal ground velocity needed to achieve 25 ?-strains in walls ranged from 36 in/s (914 mm/s) to 192 in/s (4877 mm/s) because of the high stiffness of these buildings. Such high amplitudes of ground vibrations can never be safely achieved during close-in blasting in urban environments. These excessive values stand to show how unfounded the current limits of 0.5 in/s (12.7 mm/s) and 2.0 in/s (50.8 mm/s) are when applied to massive, tall structures. This study demonstrated that upper structure motions are highly attenuated from the lower (street-level) motions because of the long travel distances up the buildings. High-rise structures are far stiffer than mid-rise and residential structures and can withstand ground vibration amplitudes far greater than the currently enforced blasting limits in New York City.

Jan 1, 2015

By Cam Thomas, Steve Bernard

Various types of blasting instrumentation can be used in the field to analyze conditions before, during and after a blast, and to indicate what changes need to be made. When different types of measurements are combined together, the blaster can end up with useful data that can pinpoint the source or sources of problems and what changes have to be made. This paper outlines two case examples where blasting instrumentation was used to overcome problems in separate quarry operations. Extensive measurements with different systems led to significantly improved blasting results.

Jan 1, 2012

By Weyman CT Ngain, Brian J. Kennedy

Innovative chemically sensitised bulk emulsion explosives and pump delivery systems have provided contractors participating in the highly competitive Hong Kong underground construction market with a safer and more cost effective approach to loading explosives.

Jan 1, 1997

By Gunnar Persson

The borehole pressure/time history of blasting practice is simulated in a twin pendulum apparatus, where the expanding shotfiring gases force two steel slab swingers apart. A pilot installation built at SveDeFo is described. The relevant factors, that govern the use of this test method as a means of classifying explosives with respect to their toxic fume potential, are described.

Jan 1, 1996

By Robert G. Lundquist

This paper is a brief summary of work done on mining applications of high energy projectiles. Full scale field testing already completed has used cannons to drive a tunnel, drill large diameter holes, do secondary breakage in an open pit mine, and scale loose rock from inaccessible pit walls. Other applications are suggested in driving development openings, particularly raises. The method will be economically feasible only if cheap liquid propellants are developed.

Jan 1, 1977

By Joshua Micah Hoffman, Jhon Silva-Castro, Kylie Larson-Robl

A coal mine impoundment failure has the potential to be environmentally devastating and life-threatening. It is well documented that after seismic events slope failures in impoundments can occur. It has been concluded that often the main driven factor of the failure is the increase in excess pore pressure due to ground vibration. A small amount of research has been done regarding the stability of coal mine impoundments under natural seismic events; however no research has been done considering vibrations from mine blasts. If it is taken into account that current environmental restrictions oblige to increase the capacity of coal mine impoundments, thus increasing the hazard of such structures, it is necessary to evaluate the effects of near-by mine blasting on the stability of the coal mine impoundments in order to mitigate and control the potential of slope failures. To study the behavior of excess pore pressure under blasting conditions, scaled simulations of production blasting events were set up inside of a controlled sand tank. The research was divided in two stages. The first one was done, using dry conditions, while in the second part, the same set of tests were performed under saturated conditions. This document shows the partial results for stage one (dry conditions). For the tests, explosive charges were set off within the sand tank at various distances to simulate different blasting distances. Information was collected from geophones, accelerometers, microphones and high speed video camera for dry and saturated scenarios and additionally from piezometers under saturated conditions to assess the behavior of the material under blasting conditions.

Jan 1, 2015

By Roy McKinstry

In March of 2001, Barrick Goldstrike became the first surface gold operation in North America to evaluate the advantages of electronic detonators. A detailed study was conducted to quantify the benefits of the use of electronic detonators to the downstream excavation, crushing and ore processing operations. The following methods were used to quantify blast performance: High speed film and video monitoring Firing time and rock response analysis of the high-speed films Digital fragmentation analysis of the post blast muckpile Vibration waveform analysis (including Fast Fourier Transforms and seed waveform modeling) Excavator performance quantification Crusher, SAG mill and ball mill performance evaluation Ore recovery analysis Cost/benefit analysis

Jan 1, 2002

By Peter Moser, G. Reihholf

Holcim, one of the world's leading suppliers of cement, aggregates and concrete, has set up a few years ago a working group “Quarry” in order to optimize the performance of its central European quarry operations in terms of work safety, environmental standards and economic performance. One of the activities of this working group "Quarry" addresses the subject of blast fragmentation in the quarries. A benchmark study of the blast work in all quarries has shown substantial differences for the various operations in terms of drill& blast costs. Especially big differences were found with respect to the drilling patterns as a function of the borehole diameters and with respect to the utilization of the borehole volume for charging the explosives.

Jan 1, 2006

By Joshua Hoffman, Braden Lusk, Kyle Perry

This study explores how different geometries affect the shock tunnel’s performance and is broken down into three phases. Phase 1: Open arena testing in which theoretical energies produced by the detonation of small (<1.0 kg) charges are compared to actual experimental values. Phase 2: Shock Tunnel testing in which realized energies are experimentally recorded for the UK and S&T shock tunnels. Phase 3: Analysis of the data to begin building a pressure-forecasting tool for the UK shock tunnel given the explosive characteristics, sample size and desired pressure and impulse.

Jan 1, 2009

By Elliott Giles

"Measuring a blast’s performance based on the bucket fill time or “diggability” has always been achallenge due to the subjectivity generally involved. The diggability of a blast is often based onopinions and speculation without the data to properly support the claim. This paper focuses howthe blast design can impact diggability and how it can be properly measured."

Jan 1, 2016

By John Cory, David Lily, Bill Hissem

The Lafarge granite quarry in Cumming, Georgia is using Principal Component Analysis (PCA) and Biplot charting to identify important variables and control air blast and vibration. Every blasting situation is unique and PCA and Biplot charting help to clarify the major variables determining air blast and vibration.

Jan 1, 2010

By Dale S. Preece, J Paul Tidman, Stephen H. Chung

"A discrete element computer program named DMC-BLAST (Distinct Motion code) has been under. development since 1987 for modeling rock blasting (Preece & Taylor, 1989). This program employsexplicit time integration and uses spherical or cylindrical elements that are represented as circles in2-D. DMC-BLAST calculations compare favorably with data from actual bench blasts (Preece et al,1993)."

Jan 1, 1997

By Randall M. Wheeler

Many of us have used a seismograph to measure peak particle velocity and frequency. But do we really understand why? Also, why do we measure particle velocity instead of displacement and/or acceleration? What is the vector sum? How do these items relate? Where does frequency fit in? This workshop will attempt to answer these and other questions. Some of the answers may surprise you, others may not.

Jan 1, 1997

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 James Tarr, Matthew Eichler, Brent Tardif

ANFO was being used as one of the blasting agents on a construction site in New England. Groundwater was encountered in numerous blast holes. The blasting contractor was employing typical explosives loading procedures for wet conditions. An abutter to the project complained that blasting caused her well water to have an odd taste and smell. Through testing, it was determined that there were hydrocarbons and nitrates in the well water. Several days later a second neighbor complained of foul tasting water; again it was determined that hydrocarbons and nitrates were present.

Jan 1, 2003

By A. Karadogan, G. Tuncer, A. Kahriman, S. Gorgun

This paper presents the results of ground vibration measurements induced by blasting operations at five different sites located close to the residential areas. Within the scope of this study, ground vibration components were measured for all blast events over a long period of time in order to predict peak particle velocity and determine the slope of the attenuation curve for five sites. During the study, while the parameters of scaled distance were being recorded carefully, suitable monitors for all blast events of five blasting sites measured the ground vibration components. At the end of evaluation of the data pairs, an empirical relation, which gives an average line at 95% confidence level, and upper bound 95% prediction line with a good correlation coefficient was established and suggested for each site

Jan 1, 2003

By John Brennan

OK, I’ll admit it: I’ve always been a big Monty Atwater fan. Not only is the man credited with being the father of modern avalanche forecasting and safety in the United States, but he is also responsible for developing the avalauncher. Through its more than 40-year history, the avalauncher has gone through many changes yet continues to prove its worth in avalanche mitigation work.

Jan 1, 2007

By Paul Downing

When was the last time the documents and paperwork were cleaned out of the glove boxes, door pockets, under the seats and above the visors in your company vehicles? Insurance cards that expired three years ago and vehicle registrations from 1999 through 2003, for instance, don’t do any good and just take up space

Jan 1, 2008