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By K R. Sharpe, A Davitt

CXA is currently evaluating, in co-operation with Inco Metals, a new idea in small diameter hole blasting - the Unidelay Nonel initiation system. In concept, the Unidelay system is a hybrid of the conventional multi-period Nonel system and the safety fuse assembly/igniter cord system. It combines the operational advantages of the latter, simplicity and flexibility, with those of the former, safety and compatibility with all commercial explosives.

Jan 1, 1982

By John A. Huber

At an underground limestone mine in the Central United States; there were plans for the installation of a limestone processing plant. The special design and layout of the plant called for the installation of a tunnel from the underground mine to the surface above. The dimensions of the tunnel would be 10 feet high, 20 feet wide, and would be 500 feet long on a 17 degree incline. The tunnel would be used for the transportation of raw stone to the surface by a conveyor. A second conveyor would transport processed limestone into the mine for storage, that would be loaded out for shipment later.

Jan 1, 1995

By R. K. Wharton

A European Directive requires that an explosive which is sold or transported within Europe must meet certain essential safety requirements from 1 January 2003. The assessment and certification of such an explosive is undertaken by an Explosives Notified Body and if the explosive meets the requirements a certificate is issued that allows the affixation of a CE mark. The presence of a CE mark ensures the product free access to European markets. The paper examines the requirements of the Directive, identifies those explosives that come within its scope, considers the role of an Explosives Notified Body, and explains the process of applying for certification.

Jan 1, 2002

By Albert van Niekerk, Mick Lownds

Overview of the UNI Tronic™ Electronic Blasting System

Jan 1, 2004

By Pierre Allard, Wilfrid Comeau

Near-field and close-in blasting can be safe and efficient, near engineered structures, if the dynamic reaction of structural members to blasting vibrations are considered. Safe particle velocity criteria can be derived from allowable safe static flexural deflections and critical frequencies. Control of close-in blasting can be accomplished using low-pass filtering of the particle velocity signal at the critical frequency. The CETE Mediterranee laboratory at Aix-en-Provence, France, a branch of the Ministry of Roads and Bridges has -pioneered this approach and successfully applied it to major road cuts and tunnels in built-up areas, as well as a major powerhouse expansion project in Africa. This approach is presently being used for a spillway rehabilitation project in Quebec, Canada. This paper exposes- the theoretical aspects and gives case histories of its use. The SCS-15 an automated, peak reading, data acquisition device is described.

Jan 1, 1991

By John L. Floyd

One of the key factors that controls the overall profitability of surface operations is the required volume of excavated material. If the overall angle of final walls can be maximized the amount of material excavated will be reduced. However, as the slope angle becomes steeper the wall's factor of safety decreases. As a result, the development and implementation of efficient wall control blast designs becomes critical to achieving stable walls. Many site specific conditions should be taken into account when defining the methods that will be used to lessen blast induced wall damage. This paper will discuss the steps needed to properly evaluate the site and develop efficient designs. Four variations of wall control blast designs will be evaluated in terms of cost and performance. In addition, the paper will include the quality controls needed to successfully implement and refine the blast design.

Jan 1, 1998

By L D. Lawrence, R S. Day, Gordon Coleman

Commercial emulsion explosives are typically characterized by their relatively high detonation velocities due to the intimacy of oxidizer and fuel and to their sensitization with glass microballoons. However, numerous blasting operations in softer, more porous rock formations are better fragmented with slower shooting explosives. Although mixtures of emulsions with large amounts of ANFO (60-80%) can considerably reduce the high velocities, little water resistance is achieved with low levels of emulsion blended with ANFO. "Water proof" blends containing typically 50 percent of emulsion become quite costly due to escalating powder factors in ANFO patterns. Blends of sensitized emulsions with 20-30 percent ANFO retain the high velocity characteristics of the emulsions as well as increased densities which can also adversely affect blasting results in softer rock formations. The introduction of a reliable and predictable on-site gassing process for sensitization and density control of repumpable emulsions, with or without added ANFO, offers the end user the option of supplying a final product more suited to his blasting needs. The capability to widely vary final product loading densities and consequently product detonation rates better tailors the final explosive to different rock characteristics. The beneficial advantages of this system in softer rock formations have been well documented. Overall comparison between these variable density products with typical repump emulsions containing solid density control will be reviewed. Besides the obvious cost advantages and safety advantages of these systems the end user is provided more definitive control of his blasting operation.

Jan 1, 1990

This paper examines the hypothesis that the fragment size distribution of blasted rock contains information about the changes in fragment sizes with distance from the borehole, and that this information can be interpreted and used to predict the effect of powder factor on fragmentation. A set of simple relationships between the fragment size distribution curve and the dependence of fragmentation on powder factor is proposed. The equations derived are compared with published data on fragmentation in small scale blasting. Two data sets were analyzed, and the results confirm the hypothesis.

Jan 1, 1997

By D. Bartley, R. McClure, W. Reisz

Ever since the 8ms criterion was developed in the early 60’s there has been an ongoing debate among many blasters as to its actual value in controlling ground vibration. The perpetuation of the myth surrounding the 8ms window can be partly attributed to its simplicity and convenience as a means for regulatory compliance. Unfortunately, the mindset that many blasters have adopted has hindered the development and use of more effective techniques and in many cases can actually be counter productive to vibration control.

Jan 1, 2006

By Tim A. Beattie, John R. Grant, David L. Kennedy

After many years of research, ICI staff have developed a numerical modelling system for the study of detonator/primer/explosive configurations. Results from this work clearly identified that current primer designs were not as effective in delivering their energy potential as needed. Alternative designs were evaluated and several prototypes, all essentially spherical in shape, were built for testing. Results have shown a significant improvement in various aspects of primer performance, including omni-directional pressure transferral and increased energy release rates. Reliable, high performance priming of explosives is now achievable for a much wider application range.

Jan 1, 1991

By W. J. Birch

The recording of information is critical to the blasting process, whether it be for planning purposes, statutory requirements or environmental compliance. The review and analysis of past data can play a key part in a blast.s design. Statutory records must be held to preserve operational licenses and well-maintained monitoring records are a vital defence for today.s litigious society. However a single blasting event can be responsible for generating vast amounts of data. This information maybe collected pre or post-blast and in their individual ways may have a requirement to be logged, processed, analysed, reviewed and reported before eventually being archived.

Jan 1, 2002

By D T. Froedge

The state of Kentucky is making some changes in it's blasting program namely instituting a training program for blasters and instituting a new classification of blaster titled "Class A Kentucky Blaster". These changes will take place within the next year and are felt to be of great interest and benefit to those in the blasting industry.

Jan 1, 1978

By Elias Poulakidas, Marco Arellano

The impact of a higher copper price on the open pit metal mining sector has derived in a faster and safer way in which the mining operation of broken and mineralised material is carried out. In this regard, a good control of bench stability allows a lesser extra removal of material and so more safety to get the planned ore. The stability is ensured through an efficient drilling and blasting, applying the current technology and available know-how. An efficient use of energy through low-density explosives which are the most adequate for the existing solid rock releasing energy in a smoother way through a deterministic detonation sequence which is the application experience presented here. This application experience has two main technological factors; the adequate type of explosive for the kind of rock, in terms of velocity of propagation (Vp) together with the use of a determined detonation sequence and the appropriate designs, which allow to reduce the level of damage to the walls and to maintain a minor backbreaking through quantification with vibration modelling carried out at the near field. The reductions achieved were 30% lower in peak particle velocity.

Jan 1, 2008

By Karl Dufresne

Blasting in geothermally high temperature ground and/or extremely reactive ground is an increasing common challenge for surface and underground mines. Many current PETN based non-electric and electronic detonators have manufacturer published in-hole temperature limits ranging from 55°C to 65°C (131°F to 150°F) and prescribed in-hole residence times on the order of days. When confronting blasthole temperatures above the manufacturer published limits, operations may request site-specific guidance and qualification for use. The advised safe loading window for in-hole PETN based detonators is often too short to be practicable for production blasting. To overcome limitations of PETN based initiation systems, surface mines with high temperature ground and/or reactive ground are known to load blastholes with a qualified high temperature bulk emulsion that are top primed with a cartridge of temperature qualified detonator sensitive emulsion plus an RDX detonating cord downline. As there is no in-hole delay detonator in this system, blasthole timing is accomplished with surface delays. Although this system is safe, top priming and surface delaying does influence floor quality and top size fragmentation, and safe loading windows times reduce blast block size and increase blasting frequency. The DynaEnergetics IGNEO high temperature electronic initiation system is rated for in-hole use in ground up to 150°C (302°F) for 48 hours. The detonator consists of a high strength detonator with an HMX base charge and thermally resistant downline. To make up a primer, the detonator is inserted into a booster charge assembly that is fitted with a small HMX shape charge. This high energy primer is designed to be compatible and reliable for firing bulk emulsions, including those with high percentages of urea inhibition to combat reactive ground. Up to 1000 detonators may be programmed in 1ms increments up to 1500ms. The system is controlled by a digital firing panel that can be used with either a wired or wireless trigger. The system enables high temperature and/or reactive ground sites to utilize in-hole delay initiation and realize the associated performance benefits. An underground mine in Western USA has several areas in their development heading with very high temperature, in view of this, they decided to use the IGNEO detonators in order to evaluate the effectiveness and performance of the system.

Jan 21, 2025

By John T. Day, Lex L. Udy, Mark L. Thomas

When we consider that the purpose of blasting is to fragment rock or ore so it can be subsequently handled and processed, we can see that the cost of blasting, in reality, affects all downstream steps of the mining (and in some cases) production processes. The productivity of all subsequent operations is influenced by the degree of fragmentation of the primary blast.

Jan 1, 1987

By D T. Froedge

A new system for acquiring blast vibration data and a method for presenting that data in such a way that there can be an extraordinarily enhanced insight into the understanding of vibrations produced by blasting is described in this paper.

Jan 1, 1989

By Zoltan Susanszky

Technical development in blasting requires improvement of industrial explosion techniques in two fields. One is to apply increasingly exact and economical solutions with more effective explosives, the other is to restrict as much as possible the environmental effect of explosions.

Jan 1, 1978

By Kazuyoshi Kawami, Fumihiko Sumiya, Kunihisa Katsuyama, Yuji Ogata, Koichi Kurokawa, Yuji Wada

When explosives are detonated in the borehole where there is an air gap between the explosive charge and the borehole of inner wall, the shock cave in an air gap travelling ahead of the detonation front sill be generated. This shock wave is called the precursor air shock wave (PAS). The explosive is precompressed by the PAS, and as a result of that the detonation failure occur on occasion. This phenomenon is well known as channel effect.

Jan 1, 1994

By Tom Hanke, Joe Strobbe

The 80 year old Theodore Roosevelt Dam built in a scenic canyon near Globe, Arizona is currently undergoing a major renovation. The old stone dam, built by hundreds of skilled stonemasons, is being covered with a new concrete face that will increase the dam height by 77 feet. The renovated dam will improve flood control and provide increased electrical power and recreation area. The contractor, J.A. Jones is constructing the new dam and powerhouse for the Bureau of Reclamation.

Jan 1, 1993

By A B. Andrews

The use of sequential blasting techniques that combine surface and in-thehole delays has provided blasters with increased flexibility in blast design to promote good rock fragmentation and displacement while minimizing offsite blast effects such as air blast, flyrock, and ground vibration.

Jan 1, 1981