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By Ajoy K. Singh, B Mohanty, P K. Singh

A study was conducted to investigate the damage potential to underground multiseam openings caused due to vibration generated by open-pit coal mine blasting. The objective was to recommend optimal explosives weight per delay to be detonated in open-pit blasts to ensure the safety and stability of underground openings. Sixteen blasts with varying charge weights and initiation sequences were conducted at Samleshawari open-pit mine and eighty four blast vibration data were recorded in the Hingir Rampur underground colliery in India. Analysis of vibration data showed that roof of the underground openings vibrated with much higher amplitudes compared to those in pillars and floors. The amplifications of vibration in the roof at the junction were upto 4.3 times the pillar vibration. It was observed that coal chips detached from roof when the peak particle velocity reached 131 mm/s or higher. The vibration magnitude recorded was higher in upper-seam openings than in belowseam openings. Rapid attenuation of vibration was recorded in below-seam openings at similar locations. Appropriate particle velocity-charge weight-distance equations were established to calculate the safe explosive weight per delay to be detonated in open-pit mine for the safety of multi-seams workings of underground mine. The support for the galleries and junctions were further modified for the working seams to ensure greater safety.

Jan 1, 2011

By N T. Moxon, L W. Armstrong

Explosive manufacturers have for many years provided a service to the mining industry which has,until recently, been unchallenged by mine operators. Today mine operators are more aware of the properties of explosives required to perform particular tasks within their operations. These properties can be reliably quantified using the test procedures described in this paper for emulsion adn ANFO based explosives. Details of an end-user sampling programme desgined to provide quality checks on explosives supplied to a mine site are also discussed.

Jan 1, 1991

By Thomas C. Palangio

Since the advent of explosives, people have been trying to mechanize the process of loading it into long, narrow holes. Automated loading frees manpower from the arduous task of charging granular, cartridged and slurry explosives. An unexpected bonus of the automation process has been the realization of some valuable side effects such as high throughputs which speed up the loading process and higher loading densities which enhance explosive performance and permit hole patterns to be expanded.

Jan 1, 1990

By Braden T. Lusk, Rex A. Meyr, Kyle A. Perry

Following three major mining accidents in 2006, the MINER Act of 2006 was enacted by MSHA and required every underground coal mine to install refuge alternatives to help prevent future fatalities of trapped miners in the event of a disaster. A polycarbonate safe haven wall for use in underground coal mines was designed and modeled using finite element modeling in ANSYS Explicit Dynamics to withstand the MSHA required 15 psi (103.4 kPa) blast loading spanning 200 milliseconds. The successful design was constructed in both half-scale and small scales in the University of Kentucky Explosives Research Team’s (UKERT) explosives driven shock tube. The constructed polycarbonate walls were tested multiple times to determine the walls resistance to blast pressure. The results for each test were analyzed and averaged to create one pressure versus time waveform which was then imported into the finite element program and modeled to compare deflections of each part to that was measured during testing for model validation. This paper summarizes the results.

Jan 1, 2014

By T Goswami

The conventional practice in open cut coal strip mining has been to blast the overburden or coal layers in separate blast events. This is done in order to maximise the benefits from throw blasting and also to limit coal losses. Each blast event usually has a particular design of hole diameters, burdens and spacings, explosive charges and blast timing in order to achieve the required blast outcome for either the overburden or coal. This means that each blast has to be separately cleaned on the surface after excavation of the previous blast. Hole locations then have to be individually surveyed and marked, holes drilled, explosives and initiators loaded and the blast fired. Each of these actions takes considerable time and resources and therefore impacts on mine productivity. The mine has to be cleared for each blast event and every blast presents a new potential source for noise, dust or vibration disturbance to the neighbouring population. Exposed highwalls are also subjected to vibration and damage from each subsequent blast event

Jan 1, 2006

By Roberto Folchi, Hans Wallin

Having so many norms and technical content of legislation to deal with is a problem that an explo-sives engineer has to face, especially when working at an international level. Each country has its own norms and legislation, sometimes even each other region or state, as if the physics of explo-sions, rock, concrete, and masonry characteristics would change across the borders. Both norms and laws are frequently out of date, being mainly developed at the beginning of the previous century and adjusted, piece by piece, to a technical and political context that is constantly changing, with adjustment being frequently adopted in a hurry, due to a problem arising such as that of internation-al terrorism. Sometime also, norms are not harmonized with those they intend to amend, so required explanations and new adjustments lead to a vicious circle that increases confusion, complexity and depresses the explosive industry.

Jan 1, 2015

By Steve Collinsworth, Nils Heinke

In 1989, I realized the definite need for change in the Blast Hole Drilling Industry. With over 25 years of experience in dealing with the industry, I am well inGormed and educated concerning the problems that occur in Blast Hole Drilling. After continues interaction with the Drill & Blast Superintendents, Drillers, Purchasing Agents, Mechanics, and others in the field, a basic understanding was developed as to the origins of the main problems that the industry f&s with their drillings programs.

Jan 1, 1997

By Kurt Oakes, Paul Worsey, Braden Lusk, Tony Brasier, Jerry Chambers, Scott Crabtree, Randy Wheeler

Destructive wave interference has been studied in theory for many years. In application however, limited information can be found. Recently, circumstances have enabled a multidisciplinary team to utilize electronic detonators and seismograph analysis to create destructive wave interference in an underground production blasting application. Springfield Underground, located in Springfield, MO, in conjunction with Orica, ETI, White Industrial Seismology, and the University of Missouri – Rolla has shown the ability to use destructive wave interference in underground blasting to reduce ground vibrations directly above.

Jan 1, 2006

By Brian Stump, David Anderson, D. Craig Pearson, Robert Martin

Mining explosions designed to move, bulk or fracture rock are often composed of a number of explosions arranged in a complex spatial and temporal pattern. The effects of the explosions are strongly dependent upon the design and implementation of this blasting pattern. This paper describes the collection, combination and visual display of multiple types of data from these explosions for the purposes of understanding the relationships between the blast design, implementation, and observations. Data sets consist of three-component ground motion, acoustic, video and high speed film, three-dimensional topography, geological and geophysical properties, design blast pattern and timing, and velocity of detonation in the explosive for individual borehole detonation times. The explosions studied include simple single-fired contained explosions, ones designed to bulk and fracture rocks and those that cast material.

Jan 1, 2000

The objective in controlled blasting is to reduce overbreak to control the final pit wall slope, shaft, drift ditch, bench, etc. to the final planned excavation limit. The six main types of controlled blasting utilized today are: 1) Line Drilling 2) Cushion Blasting 3 Smooth Wall Blasting 4) Buffer Blasting 5) Presplitting or Preshearing 6) Air Deck Presplitting

Jan 1, 1992

By Carl Lubbe, Ron Frye, Wayne Curtis, Julie Pecori, Dan Leach

Blasting conducted in the USA using the new Electronic Initiation System developed by Altech has shown that an accurate delay system will benefit the customer. Results from test work clearly showed that improved fragmentation was effected and blast vibration was at least similar to that currently found at the test venue with improvements possible.

Jan 1, 1997

By W. J. Birch, R. Farnfield, L. Bermingham

Whilst a significant body of research has been carried into air overpressure levels that arise as a result of the use of explosives, few published studies have actually tried to relate the movement of a quarry face to the resulting air overpressure produced. The aim of this preliminary investigation was to monitor a number of quarry blasts at two different limestone quarries. The first using multiple separately initiated deck charges in a multi borehole blast, the second using single column charges in a multi borehole blast.

Jan 1, 2008

By Randall Wheeler, R. Frank Chiappetta

2000 HIGH-TECH SEMINAR Blasting Technology, Instrumentation. and Explosives Applications - Orlando, Florida, USA July 24 - 27,200O 2000 BAI - PROTECTION AGAINST LITIGATION WITH GOOD PRE-BLAST SURVEYS, DAMAGE INSPECTIONS AND RECORD KEEPING 1 of 65 Good Record Keeping is Essential for: 1 ) Compliance with any prevailing Local, State or Federal Regulations, ordinances and permits. 2 ) Protection against potential litigation. 3 ) Balancing explosive consumption, use & costs. 4 ) Use in blast designs.5 ) Blast diagnostics & troubleshooting good/bad shots.

Jan 1, 2000

By Bruce Vandenberg, Andy Battfay, Don Lake, Steve Conway, Jeff Yorsz

"High-speed motion pictures are an invaluable resource for blasting analysis. Whether processed by the human eye or a computer, this imagery can provide important insight into a blast and its effects.While certainly popular, traditional high-speed film cameras hamper this process. Instant feedback is not available since film requires developing and, relevant in the case of automated analysis, film isnot immediately compatible with a computer. With these facts in mind, a new high-speed video camera system, the SVCSOO, has been developed. The SVC500 combines the capabilities of a high-speed film camera, the convenience of a solid-state digital video camcorder, and the computing power of a ‘486 PC to provide a complete, standalone platform for high-speed image acquisition and analysis. This paper will describe the design, features, and use of the SVCSOO andcompare these with the analogous aspects of film cameras."

Jan 1, 1994

By Gregory B. Poole

As part of a $3.5 billion program to improve the antiquated waste water system in the city of Atlanta, the Nancy Creek Tunnel is being constructed across the northwest portion of the city. This tunnel is over eight miles long and is being constructed using Tunnel Boring Machines (TBM) for the majority of the tunnel and conventional drilling and blasting for three shafts, starter and tail tunnels and four connecting tunnels, totaling 2400 feet in length. An extensive public relations program was developed for this project. A group effort by the owner, engineer and contractor produced a public relations program that both informed and educated the public of the anticipated perceptions and effects of the blasting and TBM activities.

Jan 1, 2005

"The objective in controlled blasting is to reduce overbreak to control the final pit wall slope, shaft, drift ditch, bench, etc. to the final planned excavation limit. The six main types of controlled blasting utilized today are:1. Line Drilling2. Cushion Blasting3. Smooth Wall Blasting4. Buffer Blasting5. Presplitting or Preshearing6. Air Deck Presplitting"

Jan 1, 1994

By Stephen Mansfield

In metalliferous mining operations, subdrill is that portion of the blast hole that is drilled below the target grade elevation, and in most cases loaded with explosives. Its primary aim is to enable efficient excavation down to the target floor level. Subdrill is often described as being expensive and that excessive subdrill should be avoided, as it can result in damage to the subsequent floor, lead to difficult drilling conditions and higher vibration levels. As a result, many operations aim to apply the bare minimum amount of subdrill in order to excavate to the target floor. At a large open cut copper operation, challenging geological structure resulted in slabby and blocky fragmentation in the stemming region, resulting in poor crusher throughput due to bridging. To overcome the poor fragmentation in the top of the bench, longer than conventional subdrill was used to precondition the top third of the bench. The technique significantly improved the run of mine fragmentation and resulted in feed to the in-pit crushers that is more consistent, which produced less crusher downtime due to bridging. A new method of quantifying the energy in a blast has been created. Termed the linear powder factor, or energy factor, the calculation considers the energy contributed by the subdrill of the upper bench and its impact on the energy in the lower bench. The technique enables blast designs to be optimised to deliver finer fragmentation and more consistent blast outcomes. To support the layer of preconditioned rock at the top of the bench, an innovative new device was developed. The device is inserted into the drill collar immediately after drilling and remains in position throughout the subsequent steps of hole depth measurement, priming, loading and removed prior to stemming. The device not only supports the broken rock at the top of the bench, but also minimises the amount of drill cuttings that fall back into the hole. Furthermore, the device helps protect the hole from damage by external factors such as weather events, drill tracks, vehicle tyres and movement around the collar during measurement and loading of the blast hole.

By W. J. Birch, D. Leckenby, R. Farnfield

The use of electronic detonators to improve fragmentation is becoming universally accepted. However their use in limiting peak particle vibrations levels is still in its infancy. Most of which is anecdotal, in that few actual scientific studies have been carried and published. This paper details the research work carried out at a limestone quarry in the County of North Yorkshire in Northern England. Here a series of blasts were carried out some used non-electric detonators whilst others used electronic detonators. The majority of blasts were carried out at the same burden, spacing and deck charge weight loadings. Initially, the key variable was the difference in detonator type and then leading on to using the electronic detonators at specific exact different detonator timing intervals. Later the study was extended to include double row as well as single row blasts.

Jan 1, 2007

By John E. Wiegand

"We will attempt to explain the basic workings of a modern seismograph and how the recorded data can be interpreted, not only for determining compliance to the regulations, but also in determining whether or not a seismograph record is accurate and valid. We will discuss some parameters that should be included in all seismographic recordings. We will give examples and use overhead slidesto show examples of both accurate and valid recordings, and tampered and inaccurate seismograph recordings. Much of the information presented will be basic in nature, and will reflect the opinions and personal experiences of the author. We ho'pe the listener will gain valuable information concerning the use and interpretation of seismographic data, as well as find interest and sometimes humor in the examples shown."

Jan 1, 1992

By Ron J. Elliott, Dylan Wedgewood

A series of five signature holes were blasted at the Highvale Mine and the resultant seismic data was analyzed to make recommendations on how best to address neighbour complaints regarding blast vibrations. From an analysis of peak vibration levels measured at the closest neighbour for blasting during 2016, it was determined that the blast vibration intensity varied between 1.4 to 4.3 mm/sec (0.06-0.17 ins./sec.), well below the level of concern for the onset of minor damage to residential structures, however, the frequency of the blast vibrations was between 2.2 and 9.7 Hz, which is within the range of the natural resonant frequency for a single story home. This was determined to be the cause of the neighbour complaints, as the home would be responding to the blast vibrations.

Jan 1, 2018