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By Joshua Hoffman, William Chad Wedding, Braden Lusk

The emergence of electronic detonators as viable products for use in production mine blasting has enabled mining professionals to rethink the traditional blast design methodologies that pertain to timing. In many ways, electronic detonators can allow great advances in productivity, cost effectiveness, fragmentation, and safety. There are a number of commercially available systems that enable users to program delay times, usually in one-millisecond intervals, according to design decisions. While manufacturers have performed internal studies pertaining to the accuracy of these systems, an independent study quantifying the accuracy of the systems has not been completed to date. The mining industry is in the business of production and any quality control endeavors to independently confirm the accuracy studies performed by the manufacturers would only detract from their bottom lines. Furthermore, limited information is available concerning the accuracy of modern pyrotechnic delay based detonators. In 1985, the Bureau of mines completed a study of three manufacturers’ electric millisecond delay detonators (Bajpayee, 1985). This was the most recent extensive independent study performed on detonators, which unitized pyrotechnic delays, from numerous manufacturers. Advances in the manufacturing process for pyrotechnic delays may have increased the accuracy of detonators using these technologies in recent years. It is commonly accepted that electronic detonators are more accurate than both shock tube type non-electric as well as electric detonators, but the relative accuracy was not objectively and adequately quantified.

Jan 1, 2011

By Wang Xuguang, Kang Tingzhang, Zhang Xiaozhi, Wang Guoli, Li Ziqianga

Emulsion powder and granule explosive is produced through airflow fluidization technology by using W/O emulsion. Maintaining the microstructure of W/O emulsion, it has the advantages of both emulsion explosives, such as good water-resistance and detonation properties and powder explosives, such as low cost and east handling. The basic theory of emulsion powder and granular explosive, choices of constituents and formulation, technology for preparation, equipment and relevant parameters, product property as well as technology for safe use have been illustrated in this essay. Based on the above illustration, related factors influencing property and use result have been analyzed.

Jan 1, 2000

By Robert B. Hopler

This paper reviews, from the historical standpoint, the development of the commonly-used terms such as "No. 6 and No. 8" with regard to detonator strengths. The origin of the strength terminology is reviewed, and the many methods developed to compare the strength of one detonator to another are described, with the good and bad points of each method outlined. The "miniature cartridge test," very highly regarded by both the U.S. Bureau of Mines and Institute of Makers of Explosives in the 1930's and early 1940's, is described in detail, as is a test developed and used by IRECO.

Jan 1, 1992

By Clara Godoy, Álvaro Dapía, Paulo Couceiro, Pablo Segarra, José Ángel Sanchidrián, Juan Navarro

This paper applies geostatistical tools in Measure While Drilling (MWD) data to estimate the probability distribution of values in all the points of the studied domain in order to assess the continuity of rock classes between boreholes. The analyses carried out by Ghosh et al. (2018) and Navarro et al. (2019) have been used as starting point of this work to classify the geotechnical rock condition in four classes: solid rock, fractured rock, cave- in rock and cavity. From it, an application for the geotechnical rock condition of orebodies have been developed, aiming at characterizing the rock before the charging the holes to minimize unexpected rock conditions and to address issues associated with charging and blasting operations. Such problems are closely related with non-optimal rock fragmentation after blasting.

Feb 1, 2020

By Othmar Mueller

Cable charges are theoretically endless. Practically,they are composed of very long sausage like explosive charges. They are primarily used for excavating ditches in soils. Blasted ditches are necessary in agriculture for irrigation purposes and for canals. Horizontal cable charges can be made by using a single or double strand of detonating cord. They can be placed into the mud at the bottom of ditches and used to clean or deepen the already existing ditch. They can also be used for soil compaction. Cable charges have been used for blasting soil in the Soviet Union, Czechoslovakia, Poland, the German Democratic Republic and Hungary. Their use was first mentioned in the first edition of Weichelt's handbook on blasting (German Democratic Republic, 1949).

Jan 1, 1976

By Lon Santis, David Leidel, John Tatom, Meredith Hardwick

This paper describes the development and methodology of the Institute of Makers of Explosives’ Safety Analysis for Risk (IMESAFR), a risk analysis software program for commercial explosives operations. IME is a nonprofit safety and security association devoted to the safe and secure manufacture, transportation, storage, and use or disposal of commercial explosives in the US and Canada since 1913. The software methodology’s basis is the U.S. Department of Defense Risk Based Explosives Safety Criteria Team’s Safety Assessment for Explosives Risk (SAFER) software. A diverse group of industry and government experts contributed to modifications to SAFER that reflect commercial operations. IMESAFR is intended to supplement the American Table of Distances (ATD) and offer standardized methods of managing risk from a wide variety of commercial explosives operations where the ATD does not apply. The modifications made to SAFER primarily involved the addition of commercial activities and potential explosives sites (PES). A review of commercial explosives accidents and operations over the last 20 years served as the basis for establishing probability of event values. An industry survey of commercial PES types in the U.S. and Canada was conducted to identify and address critical differences in commercial structures as compared to the military structures in SAFER. The paper concludes with discussion of the potential uses for quantitative risk analysis (QRA) and a description of other explosion effects software

Jan 1, 2007

By P. Ross, O. Rielo, P. Katsabanis

Selection of delay times to optimize fragmentation has been a controversial topic among researchers and blasting practitioners. The paper reviews all available experimental information, ranging from small and medium scale tests in geologic materials to small scale tests at the laboratory and synthetic materials, simulating rock. Tests have been re-analyzed and discussed in terms of the information they present and the limitation of the testing environment in representing actual conditions. New results obtained from blasting experiments in specimens made of a grout have provided a clear picture of the effect of delay on fragmentation. The grout used has a strength of 60 MPa (8700 psi), density of 2.5 g/cm3 and P-wave velocity of 4000 m/s (13100 ft/s). Each block was placed in a yoke to eliminate unwanted reflections and the desired delay was obtained using the appropriate length of detonating cord between holes or sub-millisecond electronic detonators. Delays ranged from 0.1 ms/m (0.03 ms/ft) of burden to 16 ms/m (4.9 ms/ft) of burden. Fragmentation was obtained using screen analysis of the collected fragments. Delay time has been shown to be a significant parameter affecting fragmentation and back break. Generally larger fragments and less back break was observed at short values, while fragmentation somewhat deteriorated at significant delay times, compared to what was observed at intermediate delay times. The work is now extended to include the effect of energy partition on fragmentation as well as the effect of initiation point and coupling ratio.

Jan 1, 2014

By Shih Wen Wang, Ronald R. Rollins

A blast casting model is proposed to predict the burden velocity in bench blasting. This blast casting model is the first theoretical model that 1) explains the throwing procedures and mechanisms, 2) uses the explosion pressure as the primary source in throwing rock fragments, 3) applies them to field conditions successfully. Also the predicted burden velocities are based on the rock properties, the explosive properties, and the drilling and initiation patterns. This blast casting model is programmed into a computer software "ROCKFRAG". The comparisons between "ROCKFRAG" predicted values and two field test data are in good agreement.

Jan 1, 1992

By Minoru Kawamora, Koichi Kurokawa, Kenji Hashimoto

We developed concentrated remote control blasting system to blasting simultaneously at a large number of sites in a mine of large scale. This system is consisted of three parts, the first part is a control station with high voltage power source units, the second part is a relay terminal with relaying and branching units, and the third part is a blasting machine with charging and discharging units. The control station is connected with the blasting machine by mean of control bus wire. The blasting machine adopts MBS(electromagnetic induction blasting system) for the reason of safety and good handling.

Jan 1, 1990

By Scott G. Giltner, Alex Schwenk

An iron operation sought to extend the life of the mine by conducting a major pit pushback in an area close to several public structures and the neighboring town. The result of the pushback would make millions of tonnes of ore available for mining allowing many additional years of taconite mining. This paper discusses the initial development blasts conducted for the pit pushback. For the development blasts, it was determined that no fly rock should leave the mine site and that the blast vibrations should be as low as possible, but specifically under 19 mm/s (0.75 in/s) at a nearby sewage treatment plant. One issue complicating the blast design was the variation in hole depth within any given blast. For the initial sinking shot, the hole depths varied from 6.4 m (21 ft) to 12.5 m (41 ft). In the subsequent blasts the hole depths within each blast could vary up to 5.8 m (19 ft). Various tools were employed to design the blasts to ensure there was no fly rock and that the blast vibrations were as low as possible. UAV surveys of the blast areas were conducted to provide a 3-D representation of the free faces and bench surface. The 3-D point cloud produced from this was used to measure the shape of the free faces. Once the shape of the free faces was quantified, it was possible to establish proper placement of the crest holes and develop a custom explosive load for each blast hole. In addition, signature hole analysis was performed for each blast to determine the optimum delay time that balanced the need for minimal vibration, prevent fly rock, and a well fragmented muck pile. Electronic detonators were applied to achieve the necessary control of the blast that balances these three concerns. The results of the seven blasts conducted to date provided the desired results. The peak vibration level at the sewage treatment plant for the seven blasts was 10 mm/s (0.40 in/s). The only fly rock occurred when there was a miscommunication in the blast design resulting in under burdened holes on the front row. To date, the mine has been able to safely expand the pit into an area that will add many years to the mine life. The muck piles have been well fragmented with reports from the shovel that they have all dug well.

Jan 21, 2025

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

This is the story of a blast - not a large blast by todays standards as it only involved a total of approximately 50 cubic yards of rock. Nor did this blast involve any new or revolutionary blasting technique or require involved analysis or the applications of rock mechanics theories. Instead, it was a blast that involved the tried-and-true principles of good blasting: precise alignment of blastholes; selection of explosives and detonators designed for the conditions encountered; extreme care in loading and hooking up and the use of several ingenious devices and techniques to achieve the proper loading and firing of the blast

Jan 1, 1976

By Randall M. Wheeler

Many blasting companies are using simulated production ground vibration waveforms to aid them in the control of their vibration effects. The simulations are typically produced by using a seismograph to record a signature waveform from a single hole shot and subsequently applying the various delays to be used in a proposed production design. The ability of this simulation method to give good results usually depends on three primary factors. These are: 1) the homogeneity of the seismic travel path from hole to hole; 2) the consistency of the seismic energy release per unit of explosive from hole to hole; and 3) whether or not the delays fire as planned.

Jan 1, 1991

By Jorge Flores, Dean Nichols

Some view quantitative risk assessment (QRA) as difficult to understand and complicated to use. They are comfortable with the proven reliability of quantity distance (QD) and question the benefits of applying QRA principles to explosive safety. In response to such questions, a review of the history of the American Table of Distances (ATD) provides insight to the strengths and weaknesses of the concepts behind QD tables. Additionally, a closer look at QRA features that are available today will reveal stunning capabilities and improved user friendliness not available previously. This paper looks at the early days of explosive safety, the use and limitations of QD, the meaning of risk in the context of QRA and discusses recent developments that knock down barriers previously hindering acceptance of QRA among regulatory agencies.

Jan 1, 2015

By John L. Didlinger

We all hate the paper work in keeping accurate blasting records. Nevertheless, have you ever thought what those records could show you? Think about it. Those records could show you vibrations, noise, and safety problems. They could show you the ratio of powder used and tons produced, the cost per foot, even help negotiations for pricing.

Jan 1, 1997

By James Rowland, Richard Mainiero

When most people think of explosives transport they think of a hazardous operation. We all know that we aren’t allowed to transport explosives through tunnels and are discouraged from traveling through heavily populated areas. Popular opinion suggests that explosives transport is a very risky operation. The authors decided to look into this a little more thoroughly and found just the opposite to be true.

Jan 1, 2008

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 Walt Meglasson

The Kaiser Aluminum Company Smelter, one of several in the Pacific Northwest, was built in 1942 and operated by the Olin Company during World War II and then purchased by Kaiser Aluminum after the war. At its height, the facility employed over 350 workers and was capable of producing 73,000 tons of aluminum per year. It was closed in 2000 through a combination of rising electrical and labor costs, and the inability to compete with more up-to-date foreign facilities.

Jan 1, 2008

Prepare ATF Report of Theft or Loss (ATF Form 5400.5). A Report of Theft or Loss - Explosives Materials must be prepared when it is discovered that explosive materials are missing from inventory. Submit the original to the U.S. Bomb Data Center and keep a copy for your records. The form can be obtained from the ATF Distribution Center or from www.atf.gov. Although the U.S. Bomb Data Center should be notified as soon as possible, Federal law requires notification within 24 hours of the discovery. A full inventory check is also highly recommended (but not required) to locate missing explosives and to prevent future losses.

Jan 1, 2008

By Mark S. Stagg, David E. Siskind

Five major environmental effects of rock blasting are ground vibrations, airblast, flyrock, dust and fumes. What makes them "environmental" as opposed to occupational health and safety issues is that their impacts are felt off the mine, quarry or construction site. For some impacts, safe zones are defined through experience, flyrock being a good example. Flyrock at a mine can be 1) rock thrown beyond the blast area or expected hazard zone, 2) rock thrown beyond the permit area, or 3) rock thrown more than 1/2 the distance to the nearest non-mine structure (OSM rule for surface coal mines). Rock throw of less than the "flyrock" range is then a safety issue.

Jan 1, 1997