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By Norman Paley

A blasting project was undertaken at the Teck Alaska Red Dog Mine to determine the extent that Semi-Autogenous Grinding (SAG) mill throughput could be increased by using electronic detonators. The Julius Kruttschnitt Mineral Research Centre (JKMRC) blast fragmentation, jaw crusher, and SAG mill breakage models were used to relate changes in the blast fragmentation measured with the SPLIT image analysis system to the SAG mill performance. For optimum performance a SAG mill requires a particular size distribution; a number of large rocks to facilitate breakage by impact, as few as possible middle size rocks that become critical size, and the maximum fines which will pass quickly through an open-circuit mill. Physical constraints of drill and charging equipment size limit the extent that pattern geometry can be changed, and the powder factor increased, to maximize fines. However, a growing number of studies have shown that the use of electronic detonators can lead to increased fragmentation and greater muckpile uniformity, providing an alternate means of increasing primary breakage by blasting. Unfortunately results in the literature rarely quantified the changes to the fragmentation distribution. The measured gyratory crusher fragmentation of 2,750,000t of ore was used to compare stockpiles constructed from shots using pyrotechnic detonators to those using Orica i-kon electronic detonators. In the first stage of the study, stockpiles shot using 25 ms inter-hole timing with pyrotechnic detonators were compared to stockpiles shot using the same inter-hole timing with electronic detonators. In the second stage of the study, stockpiles shot using 17 ms inter-hole timing with pyrotechnic detonators were compared to stockpiles shot using 8 ms inter-hole timing with electronic detonators. When electronic detonators were used with the inter-hole timing kept constant, fragmentation uniformity was slightly increased, but mean fragment size increased by 20%. When electronic detonators were used with faster inter-hole timing, fragmentation uniformity was slightly reduced, but mean fragment size decreased by 30%. Modeling was used to determine the SAG mill throughput which could be expected from this change in fragmentation to determine the pairs of pyrotechnic and electronic blast pattern geometries that would provide similar throughput. The economic benefit from the electronic detonator shots was calculated to assist in determining the optimum blast designs for their use.

Jan 1, 2010

By Elliott A. Pood, Ron Gilbert

Recent advances in digital recording technology have allowed frame rate increases in video recording equipment that provide the capability for super slow motion playback of commercial explosives shots. Such slow motion playback allows for the analysis of shot patterns, cap scatter, pattern failures, etc. In addition, the availability of such materials on video tape enables commercial blasters to provide a means for training current and future staff.

Jan 1, 1996

Explosive manufacture, handling and transportation is hazardous and special precautions should be taken while manufacture, handling and transportation. Various regulations and rules defined in explosive act and factories act of India are discussed in this communication. General process control measures during the manufacturing of different types of explosives are also dealt in detail. Various processes hazardous in manufacture of various explosives like slurry explosives, PETN, detonators, styphnic acid, lead azide and lead styphnate and special precautions to be taken during the manufacture of the above explosives are also discussed.

Jan 1, 2007

By L D. Lawrence

Certain blasting applications are more prone to the generation of significant levels of nitrogen dioxide post blast fumes, more commonly referred to as after blast smoke, generally ranging in color from dark yellow to bright red. This paper reviews basic background chemistry defining the observed fumes and attempts to correlate geology, blast design, and explosive composition effects on the level of nitrogen dioxide that can be observed in various blasting conditions. Additionally, a test setting for evaluating the generation of post blast fumes is presented with pertinent test data detailing generic explosive formulation modifications which effect the overall level of post detonation generation of nitrogen dioxide.

Jan 1, 1996

By Lynn Long

We have seen many new developments in the explosive and blasting accessory category, but one of the most useful items is the blast control plug. Blast control plugs are cone shaped units that are placed in the stemming just above the explosive load. They are placed about 8 to 12 inches up into the stemming material.

Jan 1, 1996

By Viktor Aranovich, Thomas E. Brown

The Almalyk Integrated Mining and Metallurgical Plant is located near Tashkant in Uzbekistan and is one of the former Soviet Union's largest copper producers. Almalyk consumes about 10,000 metric tonnes of explosives annually and expects this requirement to double by the end of the century as they implement a program to boost mine output.

Jan 1, 1998

By Jerry Wallace

Two recent-release boulders posed serious threats to public transportation and utilities in Washington State. Both required challenging drilling and blasting solutions.

Jan 1, 1997

By Luke Thornton, Jack Janssen

An unconventional drill pattern is used in an aggregate quarry to reduce pioneering costs. The site is the Iron Mountain Quarry, Granite Falls, WA., an aggregate quarry with an annual production of in excess of 1,000,000 tons. The problem is to pioneer a forty acre addition of on top of Iron Mountain. The entire area had a vertical relief of fifty to one hundred feet with no level surfaces. How does one achieve the minimum cost?

Jan 1, 1997

By Wilfrid Comeau

Vibrograms, which last significantly longer than the actual blast (say 10 to 15 cycles or more), may be signalling an elastic response, which is not uniquely blast related. For example, geophones mounted on a part of a structure, which can elastically resonate at a frequency included in the seismogram, may not show the structure’s real reaction to the blast. This resonance usually amplifies the ground vibration. This contribution examines one particular case where blasting excited and amplified a resonant ground response, and the method used to significantly reduce or eliminate this undesirable condition.

Jan 1, 2007

By John Petty, John Loviza

As a blaster, have you ever had that uneasy feeing in the pit of your stomach as a codes enforcement official drives onto your jobsite? Have you ever needed an ally in a court of law against an unjust damage claim? Have you ever wished for a better and more open relationship with the guys who wear the badges?

Jan 1, 1996

By J E. (Boet) Coetzee

SAFEX International, as the name suggests, is a global organisation, which has the fundamental objective of improving the safety of operations concerned with the manufacture, storage, transport, and use of commercial and military explosives and pyrotechnic products throughout the world. It is a nonprofit making organisation of manufacturers of explosives from all parts of the world, founded in 1954 with the aim of exchanging experiences within the explosives industry. Every third year SAFEX organises a Congress during which members present papers on selected themes and discuss reports of significant incidents that occurred since the previous Congress. Admission is for SAFEX members only, thereby creating a safe environment for discussing problems “within the family”. The XV Congress will celebrate the Association’s 50th anniversary in Geneva where it was founded. An overview of the Congress indicates its structure and covers aspects such as the training event, technical seminars and the themes for the plenary sessions and associated workshops. The paper also highlights the special event for the chief executives of member companies and the review of incidents that occurred in the industry since the last Congress. The Congress concludes with a social programme for delegates and their partners on the last day.

Jan 1, 2005

By T N. Hagan

Where explosion energy moves rock from the in-situ to its desired location without considerable assistance from digging and/or hauling equipment, good fragmentation is of minor importance. Maximum displacement must remain uppermost in the mind of the blast design engineer.

Jan 1, 1979

By A Lance McAnuff, Andrew Curic

Until relatively recently, underwater blasting operations for channel deepening, dock construction and pipeline crossings of lakes, rivers and streams were conducted without much regard for the potential side-effects on aquatic organisms.

Jan 1, 1997

By Koichi Kurokawa, Takeo Ueda, Masahi Nakano, Yoji Tasaki

A lightning strike generates several 10kA and several billion volts, and earth currents generated by lightning is dangerous to some underground and all surface blasting operations. In order to evaluate the safety against lightning in conventional electric firing method and electromagnetic induction blasting system, a test is conducted by connecting a wire with an impulse generator. Frequency of impulse current used in the test is 17kHz and the waveform is a vibration type and the duration time is 250 ~usec. The results of the test show that induced current increases with the increasing of impulse current. In the case of MBS connection, when maximum primary current is 1700A, Maximum secondary current is 11.8A and the electric detonator is fired at this condition.

Jan 1, 1988

By J Edmund Hay

Previous work by the Bureau of Mines to develop a test for determining the initiating strength of commercial detonators has been modified and extended. Recently reported results by the Bureau used a homogeneous liquid explosive to avoid the complicating effects of inhomogeneities; however, due to the belief that there may be essential differences between the initiation mechanisms of simple liquids and multi-phase mixtures and the fact that almost all commercial explosives are in the latter category, the experiments have been modified accordingly. The acceptor explosive is now a mixture of explosive-grade ammonium nitrate (AN) prills, methanol (MeOH) and nitromethane (NM). An additional change has been the use of the United Nations (UN) cap sensitivity test configuration in which the detonation witness is the degree of compression of a lead block, which is a quantitative measure of the response of the explosive. Results indicate that this mixture has sufficient range of sensitivities to be useful in comparing the strength of commercial electric detonators.

Jan 1, 1993

By Paul Worsey, Matthew K. Coy

New blasting mat designs are currently tested in the field on actual blasting jobs and only undergo qualitative rather than quantitative assessment. The majority of matted blasting occurs in trenching in which the blast designs and field conditions vary considerably. In order to assess a new blasting mat material and design, a new standard test was devised.

Jan 1, 2015

By Gary Kahn

In this document the VODR is discussed from a technical point of view and is intended to give the reader a feel for the design of the instrument, its technical specifications, and its limitations. It is not intended as a tutorial on the use of the instrument in the field.

Jan 1, 1989

By Mark Svinkin

To save time for construction of coal pits, the contractor decided to combine erection of the tower pitheads with digging of skip shafts to the depth necessary for placing proper coal pit equipment. It was obvious that blasts used in shaft faces and lifting machines installed at a lower part of the pithead could excite vibrations of an upper part of the pithead with curing concrete. The contractor was concerned about vibrations of pithead concrete structures and the disturbance of freshly poured concrete in forms at a top of the pithead as a consequence of structure vibrations. The results of a study of the tower pithead structure vibrations from blasting and operating machinery, and effects of structural vibrations on curing concrete are presented. Structural vibrations were measured at the tower pitheads of two coal pits from twelve blasts. Records of horizontal and vertical displacements were superposition of harmonic low-frequency damped vibrations and sporadic high-frequency damped vibrations with a variable frequency. Low frequency vibrations attenuated during 8-13 s after the last delayed blast. Measured values of the natural frequencies of pithead horizontal vibrations coincided with the calculated frequencies of horizontal bend vibrations. An increase of a face depth from 18 to 50 m diminished 16 times horizontal bending vibration displacements of concrete structures. Measurements of vertical structural vibrations from blasting demonstrated increasing of vertical pithead displacements with the rising of structure elevations. This is evidence of the pithead longitudinal tension. The holes with charges were not properly condensed for one blast. As a result of incompact stemming, the blast substantially increased the energy of airborne pressure waves, which triggered natural vertical vibrations of the pithead with high displacements.

Jan 1, 2004

By Kaushik Dey

Bord and pillar is the most predominant method of wining of coal in Indian underground coal mines. Development heading in coal mines often encounters roof stability problem and results in roof overbreak. Research on this reveals that the blast-induced ground vibration may have significant contribution in roof overbreak, especially, when solid blasting is carried out in the bord and pillar method. Solid blasting, in general, is associated with higher charge confinement due to lack of free face and generates higher ground vibration, which in turn results in excess overbreak.

Jan 1, 2008

By A. Ravi Kumar

A trench is a structure to accommodate fluid carrying pipelines for water, gas, petroleum products etc. Trench serves the purpose to haul the fluids in bulk over long distances safely and economically. Use of pipeline for moving oil and gas was essentially a post World War II development, but now it has acquired its own importance.

Jan 1, 2008