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By Scott Giltner, Allan Koski

Blasting is one of the lowest cost yet most critical parts of the mining cycle. This paper discusses the findings of an audit conducted on the blasting operation at an iron ore mine. The purpose of the audit was to review current blasting practices in order to identify opportunities for production/cost improvements. The approach taken in the audit was to observe general blasting practices, their related downstream effects and to compare current procedures to established best practices.

Jan 1, 2009

By Calvin J. Konya

Many controversies and differences of opinion exist in blasting technology. The primer location in small diameter dynamite columns is an example of one of these controversial areas. It is generally agreed that in rotation firing of small diameter blastholes, primer placement near the bottom of the borehole is beneficial since it reduces the likelihood of cutoffs. The controversy results in the actual location of the primer in the bottom of the blasthole. Some references indicate that the primer cartridge should be the first cartridge in the bottom of the hole, with the cap pointed toward the collar of the hole. Others indicate that performance is improved with no sacrifice in safety by placing a tamped cartridge first in the hole, and the second cartridge being the primer. The following investigation provides some factual data for consideration.

Jan 1, 1980

By D G. Dressler, Paul Yeager

A previously little-known facet of seismic frequency spectrum analysis is gaining significance. The frequency spectrum of seismic waves promulgated from blasting is a significant factor in causing blasting complaints and threshold (architectural type) damages.

Jan 1, 1987

By He Guangyi

During rock blasting in extending deep cutting from Jiu Li Mountain to Dong Zhuang Village in Jiao Zhi Railway line, we have drilled deep hole with large scale diving drilling machine and successfully carried on controlled blasting. This has provided new experiences for rock blasting in extending existing cutting. The aim of this article is to provide an introduction to bench height, blast holes arrangement, powder charge calculation, and detonating technique during blasting.

Jan 1, 1997

By Lewis L. Oriard

Ground vibrations associated with blasting are generally in a higher frequency range and of shorter duration than those generated by earthquakes, and the intensity scales for earthquakes cannot be applied directly to blasting vibrations without modification. Further, the profession does not need an intensity scale merely to estimate vibration intensity. If the blasting in question was not monitored instrumentally, it is a simple matter to estimate the range of intensities based on published prediction formulae or data from various sources such as Oriard (1), Nicholls et al (2), Hendron and Oriard (3), Siskind et al (4), and others. However, the profession has a serious need, for purposes of evaluating damage claims, to understand the relationships between vibration intensities and the levels of observed effects. The criteria for threshold damage do not apply to typical cases which usually involve structural damage. If the damage in question would have required ground vibration with a particle velocity of, say, 20-120 ips, damage is not verified by showing that the vibration merely approached a suggested limit to avoid threshold damage. That is not the question. This paper provides some guidelines for comparing severity of damage to intensity of vibration which would be required to cause such damage, much as is done when determining earthquake intensities. In addition, this paper includes a discussion of strain amplitudes induced by environmental forces, the predominant causes of damage to structures. Also, certain popular myths regarding blasting damage are discussed in the paper. Due to space limitations, the paper will not include a discussion of airblast effects.

Jan 1, 1989

By William H. Snyer, Victor A. Sterner

A cache of buried explosives was discovered by ICI Explosives, USA Inc. at one of their sites near Gillette, Wyoming. An intensive investigation conducted by ICI management indicated that nitroglycerin sensitized dynamite might be present. Information also indicated that up to 20,000 pounds of explosives may have been buried.

Jan 1, 1997

By Fumihiko Sumiya, Yuji Ogata, Masahiro Seto, Yukio Kato, Yuji Wada, Kunihisa Utsuyama, Yoshikazu Hirosaki

It is well known that emulsion explosives can be dead-pressed especially in underground blasting. Voids in emulsion explosives will affect such malfunction of explosives. To clarify the factors that affect the dead-pressing phenomena, the characteristics of the pressure wave propagation in emulsion explosives were investigated. Three types of microballoons .or microbubbles, glass microballoons(GMB), resin microballoons(RMB) and chemical gas bubbles, were used as sensitizers for emulsion explosives. The pressure profiles inside the explosives were measured to determine the effects of the microballoons or microbubbles contained. The underwater explosion test and the large-scale drop hammer test were carried out to load the explosives with a dynamic pressure and a quasi-dynamic pressure respectively. In the underwater explosion test, the pressure profiles in the emulsion explosives were measured by a piezo-electric pressure gauge inserted to the center of the explosive cartridge which had a diameter of 30mm. In the large-scale drop hammer test, the same type of pressure gauge was placed at the bottom of the explosives. From these experiments, the following results were obtained ; A) The pressure profiles in the sample explosives sensitized by RMB or chemical gases were sharp, while in the sample explosives sensitized by GMB the profile was broad. B) The peak pressure levels in the sample explosives sensitized by RMB or chemical gases were twice as high as that in the sample explosives sensitized by GMB in the underwater explosion test. However in the large-scale drop hammer test, the amplification of the peak pressure is low compared with in the underwater explosion test. C) The impulse value was independent of the types of the microballoons or microbubbles in both tests. It was concluded that the type of the microballoons or microbubbles significantly influenced the characteristics of the pressure wave propagation in emulsion explosives.

Jan 1, 2001

By Thomas A. Gelormino, Ulrich La Fosse

"Deep blasting was used to densify foundation soils for a large manufacturing facility inChicopee,Massachusetts. A 360,000 square foot building, whose construction began inthe summer of 1990, is founded on alluvial deposits up to 90 feet in depth. These deposits are comprised of saturated very loose to loose fine to medium grained sands with traces of silt and gravel. During the building foundation design it was found that to withstand earthquake forces without soil liquefaction, it would be necessary to improve portions of the alluvial deposits by densification. The zone in need of densification extended from approximate depths of 20 to 50 feet. Several conventional densification methods, including vibrocompaction and deep dynamic compaction, were evaluated along with deep blasting. Detonation of 1-3/4 inch diameter charges of 65 percent gelatin dynamite (Atlas Power Primer) installed inside 2-inch diameter PVC casings to a depth of up to 40 feet, was used to achieve the desired densification. This method was selected over others due to its lower cost and decreased construction time. Although used in New England once in1940 for a dam and once in 1960 for a transmission line tower to improve foundation soils, there is no precedent found in the literature for densification by blasting to improve liquefiable soils below a proposed building. Details of a test program and the production blasting, including vibration data are presented. Pre-and post-blasting data conclusely shows an increase in the density of the sand deposit after blasting."

Jan 1, 1991

By O E. Crenwelge

Seismograph measurements are usually made near blasting operations solely for the purpose of monitoring compliance with governmental regulations. However, recordings of seismograph signals have far greater potential than this, if the proper procedures are used for analyzing the transient data.

Jan 1, 1991

By Zoltan Susanszky

This paper discusses problems encountered when blasting under rivers for pipeline crossings. Many pipelines have recently been laid under the Danube River. Great care had to be taken to determine limits of detonation impulses from blasting operations in order that no damage would occur to structures at the water's edge, boats, and swimmers. Equations were derived from the results of this study which enable prediction of impulse levels.

Jan 1, 1977

By Jack Elorenta

A recent forum of mine operators revealed a continuing strong interest in alternative methods of freeing rock. A Rand Corporation report lists a continuous mechanical machine that would replace drilling and blasting as a priority for mine operators. Meanwhile, mounting evidence documents a dramatic cost benefit in processing where increased blast energy is available. The reasons for this dichotomy may be due to a number of factors.

Jan 1, 2002

By T J. Wilton, K A. Broadhurst

The United Kingdom, although a relatively small island, has a wealth of mineral deposits, coal, granite, limestone, gypsum, lead, florspar, etc. Coal is a major source of energy with 71 opencast coal sites, 52 using explosives. Many of these sites are in rural areas, the average area worked being 250 acres. The smallest is 35 acres, the largest 2,000 acres, but only 600 acres can be operated at any one time.

Jan 1, 1981

By T Guiliani, F Ottuonye

Explosives casting is gaining increasing popularity as an overburden removal method in strip mining because the coats of using explosives to cast a percentage of the overburden to the spoil are lower than the costs of using stripping shovels or draglines to do all the overburden removal. This is due to the rising capital and operating costs of draglines and shovels.

Jan 1, 1989

By Stuart Brashear, Lee Schettler

"The effect of water on several ANFO/emulsion blend ratios is documented by both physicalobservations and analytical testing to demonstrate the effect even small quantities of water canhave on water resistant blends."

Jan 1, 1996

By Carlos Agreda

"In the present article a case study of ammonium nitrate in mine water is briefly analized and discussed. Causes of mine water pollution from AN are very well identified and emphasized.Some preventative measures, as well as, some methods of monitoring and control to minimize, mitigate and/or avoid mine water pollution are recommended."

Jan 1, 1999

By C De La Cruz

The use of a thin-film piezoelectric stress gauge to determine the pressure profile in a detonating explosive has been demonstrated. These PVDF gauges have measured, in the borehole, the Chapman-Jouget pressure and the release adiabat of the detonation products for several explosives including ANFO and ANFO/emulsion mixtures. The technique can provide: (1) a direct measure of the blasting stimulus, (2) a sensitive QA tool for the blaster, and (3) a means to examine the magnitude and effects of preshock from adjacent bore holes. The PVDF pressure gauge is self powered, can measure pressure from a few bars to 400 kbars, has high time resolution (0.05 µsec), and is easy and economical to use.

Jan 1, 1997

By Lawrence Mirabelli, William Hissem, Gary Veltrop

Capital Quarries Company, Inc., Jefferson City MO produces aggregate products for road base, asphalt, concrete and concrete block. With their production quantities small in comparison to those produced by the goliaths of the aggregate industry, they find it necessary to constantly stay on the leading edge of best practices for cost control, process and production improvement to sustain a successful business. In the words of Eric Strope, President, “The safety of our employees is foremost. They all work hard each day. They are focused on keeping our cost to manufacture down. As I see it, we cannot work any harder so we must work smarter!”

Jan 1, 2009

By Patricia Mendoza Watson, Lundquist Robert G

The velocity with which the burden moves after blasting is of concern for safety and economic reasons. Models developed for motion velocity by various researchers were reviewed and likely model parameters were used to develop statistically significant models. Regression analysis and residual analysis were used to determine the model coefficients and the accuracy of the models.

Jan 1, 1990

By Joseph Meyers

Explosives techniques and technology are constantly evolving and improving, yet basic communication and business skills are not being used regularly. Many potential blasting projects never occur due to simplistic, basic factors, such as a lack of communication. Articulate communication is the key component in the blast approval process, which has changed remarkably from how business was conducted fifty years ago. Imperative to the approval process is communication outlining the safety and benefits of the blasting project. Information and transparency with the stakeholders and the Authority Having Jurisdiction (AHJ) will greatly improve the chances of having a blasting project approved. This open communication starts at the inception of the project when the memorandum of understanding (MOU) is obtained, and involves the AHJ through all steps of the approval process. The blasting industry and regulators must work collaboratively to improve safety, security, regulations and licensing. Implementing state of the art blasting techniques, security, safety measures, vibration monitoring and strict licensing allows the AHJ and all stakeholders to remain integrated and informed, contributing to process approval. Regulatory operators should strive to achieve success thru communication, cooperation and compliance which is accomplished thru continued education and transparency. These steps, combined with regular meetings, has proven to be a benefit to both industry and regulators. Relationships are built through trust, teamwork, transparency and communication –including the take holders and AHJ in the approval process from the inception solidifies these relationships and improves teamwork

By Rolly Thorpe

Bulk emulsion explosives have been used at surface mines and quarries for many years. Recently, this technology has been adapted for underground use in relatively confined work areas and in smaller diameter blastholes.

Jan 1, 1994