Search Documents

By Yasunori Kosaka, Junya Tokita, Aramaki Shosaku, Inoue Junji

Light ANFO that satisfies blasters and customers who want to reduce the amount of explosive consumption without changing blasting effects and designs and passes Cap sensitivity test regulated by law. The reduced loading density of light ANFO reduces the amount of explosive consumption. The loading density of conventional ANFO is 0.X-0.9g/ml, while the loading density of light ANFO is 0.7-OXgiml. The detonation velocity of light ANFO is maintained not to reduce blasting effects. Detonation velocity of conventional and light ANFO using steel tube of inside diameter 36 mm are 3200 - 37OOms. detonation velocities are the same though the loading density of light ANFO is reduced by O.lg/ml. This suggests that the reactivity of light ANFO improves.

Jan 1, 2002

By Robert B. Hopler

The hazards which naturally prevail in underground coal mines, always severe and unpredictable due to the loosely-consolidated strata in which coal is frequently found, are increased by the commonly-occurring combination of coal dust, methane, and explosives. It was recognized by the mid-nineteenth century that coal dust was the basic factor contributing to disastrous explosions killing hundreds of miners, and that the ignition of methane gas was often the source of the coal dust explosions. It was apparent that preventing the ignition of methane was a critical part of avoiding these disasters, and it was also apparent that one cause of such ignitions was the firing of explosives. In addition, it was found that dust explosions were often initiated by blown-out shots of explosives in the absence of methane.

Jan 1, 1996

By William Reisz

Over the years as surface mining operations have become more sophisticated, angle drilling has become a more popular blast design technique, especially in areas where overburden and stripping ratios have increased. Another method of blast design is the staggered pattern, which greatly improves explosives distribution within the blast. While both methods present some engineering challenges, this paper will discuss how the two methods can be combined to enhance fragmentation, improve cast percentage, drill production ratios and highwall control. A practical engineering approach will be presented as well as a discussion on the discipline required to maintain a quality blasting plan.

Jan 1, 2002

By Richard Goodridge, Stephen Thomsqn, S Rodgers, D Tunaley

The mining, quarry and construction industries are facing’new challenges everyday. These challenges can be imposed by economic objectives or through external factors such as extreme geological conditions. Simultaneously, all mines, quarries and construction sites are facing more and more stringent environmental requirements.

Jan 1, 1998

By Jon Hurt, Brent Meins, David Vardiman

"Two test blasts were conducted at the Sanford Underground Research Facility to establish optimum blast designs and to limit blast effects on existing research rooms and equipment in preparation for the largest deep underground excavation in North America. Located on the 4850 Level (4,850 ft below the surface)at the former Homestake Mine in Lead, SD, this excavation is part of the U.S. Department of Energy’sLong-Baseline Neutrino Facility that will house particle detectors for the international Deep Underground Neutrino Experiment hosted by Fermilab. A large array of seismographs was deployedthroughout the 4850 Level to measure ground vibrations and airblast pressures in tunnel drifts and in lab spaces."

Jan 1, 2017

By A R. Cameron

"The number of commercial explosive products available to the mining industry has been steadilyincreasing and associated with this there has been an increase in the range of characteristics or properties of them. This has lead to increased difficulties in selecting the most appropriate explosive for a particular blasting situation. Techniques are available that can be used to evaluate and compare the characteristics of explosives under a range of conditions. Also, the techniques are used to assess the variability in the characteristics between batches."

Jan 1, 1994

By Neal Lee, Braden T. Lusk, Jhon Silva-Castro, Patrick J. Jenks

"Timing and charge sequence are very important for optimized blast design. Traditional nonelectricinitiation systems have moved the industry toward a system of delays consisting of hole-to-hole androw-to-row timing sequences that mimic the application of nonelectric surface delays or dual delayinitiator systems that have been prevalent in the blasting industry for many years. The increasedutilization of electronic detonators allows for the use of Regular Rhythmic Timing (RRT) utilizing onlyone delay between charges and a selected charge firing sequence. The hole to hole and row to row (HHRR) timing method has been utilized for blasting optimization and allows for simplistic changes to the tie in phase of the blasting sequence. When using this traditional timing methodology, for some specific cases related to the number holes and rows, crowding occurs in the delay between charges with subsequent increase in the peak particle velocity (PPV) produced by the blast. This is in contrast to RRT where the timing between the delays remains constant."

Jan 1, 2016

By Ken Cross

This paper aims to demonstrate that explosives organizations and workers have a legal, moral and financial duty to be able to demonstrate their competence when required, and how that may be achieved at any level from explosives storekeeper to senior explosives engineer on a major project. The concept of competence is outlined, as are the benefits to members of staff, management and the organization, particularly in a regulatory regime that includes competence management as a key performance indicator.

Jan 1, 2013

By Mark S. Rayson, Jessy Lee, David O. Johnson, Matthew R. Rawls

The ability to manipulate the structure of liquid chemicals in an explosive is important in mining applications, where precision blasting is crucial for the safe, reliable, economical and eco-friendly extraction of ores. Static mixers allow explosives, emulsion-based in particular, to be custom-made as they offer precise and reproducible mixing without the need for moving mechanical parts. In this paper, we perform numerical simulations on the laminar mixing of two nitrate-based fluids in a Kenics static mixer unit for various mixer parameters. Two numerical methods were investigated in the study of the mixing pattern: solving the mass transfer equation and using particle tracking. The former introduces artificial numerical diffusion which can lead to spurious smearing of the component boundaries, a problem that can be avoided with the latter technique. We have also demonstrated that the particle tracing method is capable of qualitatively predicting the blending patterns under the conditions studied.

Jan 1, 2014

By Don W. Lake

Of all the blast monitor& instrumentation systems and techniques av&able today, highspeed photography and videography remain as the most valuable, stand alone, diagnostic techniques to evaluate full scale blasts in the mining and explosives industries. Highspeed image data, coupled with information from other instrumentation systems, such as continuous VOD records, seismographs, laser surveying systems, refraction seismographs, etc. can eIiminate many assumptions about what actually took place in a blast. Thus, diagnostic confidence in evaluating both good and bad blasts is increased, and optimum blast designs are achieved considerably faster when compared to the trial and error approach or relying on just the experience factor.

Jan 1, 1992

By Lon D. Santis

This paper summarizes explosives transportation incident and accident data collected by the U.S. Department of Transportation (DOT) from 1993 to 1998. The paper briefly describes the legislation and regulations that cover hazardous materials transportation. The multimodal incident data collected by the Research and Special Programs Administration (RSPA) contained 86 incidents involving Class 1 materials during transit. Thirty-two occurred on public highways. The Federal Highway Administration (FHWA) data showed there were 8 1 motor-vehicle accidents involving explosives. The FHWA Crash datafile extract contained 649 records categorized as involving Class 1 materials although closer analysis revealed that nearly 90% of these did not involve explosives. In both databases, there were no fatalities caused by the explosive materials although 7 fatalities were the result of injuries suffered during the motorvehicle accident. There were also no serious explosions during any of these incidents or accidents. The paper concludes with an analysis of the risk involved with transportation of commercial Class 1 materials on the highway.

Jan 1, 2000

By Bibhu Mohanty, Sheng Huang

Accurate measure of fragment size distribution is a key objective in all blasting and crushing operations. Several generic distribution functions have been devised to describe the degree of fragmentation for the representative range of fragments from selected measurements. The application of four distribution functions, i.e. Rosin-Rammler, Swebrec, Grady and Gilvarry, in describing fragment size distribution of impact-induced fragmentation of a limestone rock has been investigated. A modified Hopkinson Pressure Bar experimental set-up is used to control both impact velocity and energy input into the target rock. The feed size in the sample holder is varied from 6.35mm to 15.88mm in three ranges and the impact velocity up to 14m/s. The size distribution in the product is determined by sieve analysis for a range of impacts. The experimental results are fitted to the four distribution functions to examine their relative accuracy and reliability.

Jan 1, 2016

By Sven-Erik Johansson, Gosta Rundqvist, Donald Jonson

In Stockholm a new road traffic system called Södra Länken (Southern Link) will be in operation in late 2004. The total length of the road system is 6 kilometres of which 4,5 kilometres run through tunnels under suburbs immediately south of Stockholm inner City. The new traffic tunnels together with existing Metro tunnels, which mostly are in rock, will be the determining factor for blast design for many projects in the future. To set reasonable and safe permitted vibration levels the Swedish National Road Administration, Stockholm Region and Stockholm Transport Rail System have together financed a project to determine guide levels for blast-induced vibrations in traffic tunnels in rock. The purpose of the project has been to establish guide levels that are appropriate for different types of rock tunnels.

Jan 1, 2004

By John Tatom, Michelle Crull, Robert Conway

The US Department of Defense Explosives Safety Board is sponsoring the development of a risk-based explosives safety siting program, SAFER. The fragment and debris hazard generated at the potential explosion site (PES) is critical at an exposed site (ES) over a significant range of standoff distances. The Science Panel Impact Debris Evaluation and Review (SPIDER) test program has been planned to develop improved predictions for the hazards inside an ES by fragments and debris. Data will include the mass and velocity required for perforation of the test cross-section and the characteristics of all debris produced inside the ES.

Jan 1, 2010

By Theirry Bernard

The era of non-electric systems as an initiating system has revolutionised the blasting world by introducing a very safe initiating system that is reliable, with initiation sequence possibilities that are superior to those of purely pyrotechnical or electric systems. Electronic initiation has brought with it accuracy, programming and controls that were lacking in the non-electric systems. However, it has also led to a certain degree of complexity, which works against user-friendliness, sometimes introducing a few constraints that are balancing out the intrinsic performance of electronic detonators. The introduction of a hybrid initiation system, Electronic and Non Electric, offers accuracy, and flexibility that were lacking in non-electric systems, whilst removing the inherent complexity of electronic systems. This paper endeavours to summarise the advantages and disadvantages of non-electric and electronic initiation systems that have been recorded after years of experience on site. The paper will then describe how a hybrid system only keeps the advantages whilst eradicating the disadvantages, via a case study.

Jan 1, 2007

By W. J. Birch, R. Farnfield

The use of electronic detonators to control blast vibrations has been previously established by many authors. This is performed by determining the optimum delay period between the blast holes for a particular pattern that can accurately control the firing frequency of the blast, which in turn has a direct bearing on the frequency composition of the ground vibrations recorded at a particular location. This was established by Pedgen, Birch, Hosein & Farnfield (2006) whereby like-for-like comparison tests between non-electric and electronic blasts were carried out in a limestone quarry in northern England. They demonstrated that resulting peak particle velocity values recorded at near and mid-field distances were primarily a product of the firing frequency of the electronically initiated blasts.

Jan 1, 2009

By Lon D. Santis

This paper describes a lightning warning system (LWS) in operation at the U.S. Bureau of Mines' (USBM) Pittsburgh Research Center (PRC) from December, 1989 to April, 1991. An electric field mill measured the DC atmospheric electrostatic field. Also, an economical on-line weather data service provided lightning location maps and other weather information. A system such as this can significantly improve the safety of explosive handling. The use of these two methods addresses the detection of thunderclouds building overhead and the prediction and tracking of developed storms. Warning reliability of the system was very good when data from both sources were considered. Experience showed, however, that use of either system alone would not provide adequate reliability in most situations. Some problems occurred with the field mill and there is some question whether the instrument is compatible with harsh mining environments or could be made portable. Another method ' of measuring electric field based on fiber optics is discussed. This technology may be able to overcome the problems with field mills.

Jan 1, 1993

By Ray Slavin, Remi Proulx

The Meikle Mine is a mature underground gold mine utilizing primary and secondary longhole open stoping method with delayed backfill. Combined production with the newly developed Rodeo Mine is 4700 tons per day (4265 tonnes per day) of ore. The vast majority of Meikle Mine production comes from secondary and remnant stope blocks. Remnant stopes are ore blocks that were left behind in the initial mining sequence due to various reasons. Mining of these remnant blocks has created many challenging blasting situations. The application of electronic initiation to blast remnant stopes has proven extremely beneficial. Electronic initiation has provided the blasting engineer with a high degree of flexibility with respect to timing to successfully extract these difficult stopes. Post blast assessment of the remnant stopes using the mine’s cavity monitoring system (CMS) demonstrates that the mine is maximizing ore recovery and minimizing waste dilution. The largest remnant stope blast to date required 54 holes and produced 6700 tons (6075 tonnes) of ore. Another area where the application of electronic detonators has proved successful is in the extraction of slots in which ground conditions are extremely poor. Taking the slot blasts in one shot with double-decked holes as opposed to two single-decked shots has eliminated the need to clean and or re-drill holes. The ability to open the slots in one blast has helped reduce the total mining cost. This concept has recently been expanded to blast complete stopes in one shot. This reduces the stope cycle time considerably and allows the mine to bring ore forward. Current plans for 2004 are to excavate 50% of mine wide stope production using electronic initiation technology.

Jan 1, 2004

By Ken Eltschlager, J Silva Castro, J. M. Hoffman, Braden Lusk

This case study focuses on analysis of sounds inside a house induced by blasts as result of surface mining coal in West Virginia and how to better communicate technical information to the public. The field study included a house wide vibration and sound monitoring system installed in a home which was subjected to blasts at varied distances and direction. The structure response was separated into ground vibration and airblast induced movement due to the differences in their times of arrival. This signal was then compared to the sounds recorded to determine which component of blast (ground vibration or airblast) induced the maximum sound. Findings shows that blasts at distances less than 762 meters (2,500 feet) had maximum sound responses from both ground vibration and airblast. While for blasts beyond this distance the maximum sound response was caused by ground vibration without exception. The kitchen generally created the most sound. The second phase of the study was to gauge the public’s response or preference to technical information. Three hundred and forty eight (348) telephone surveys were conducted in Logan and Boone counties West Virginia. Based on the survey, the public prefers units of pounds per square inch (psi) for airblast and millimeters of displacement for ground vibration. Ultimately a public relations plan was developed based on the results.

Jan 1, 2012

By W. Sharkey Bowers

This study was undertaken in order to determine a conservative estimate of the attenuation rate of vibrations through the shallow limestone in South Florida due to quarry blasting.

Feb 1, 2020