Search Documents

By Jeff Peterson, Alastair Grogan

During the winter of 2001/2002, a number of seismic exploration projects were carried out in the Mackenzie River Delta area of the Northwest Territories, in Canada. The purpose of the seismic projects was to identify potential drilling targets for subsequent drilling programs, using explosives as a seismic source. Recent changes to fisheries regulations meant that blasting under lakes, the Mackenzie River and offshore from the delta, was not allowed to induce water overpressures in excess of 100 kPa in these water bodies, and that a water overpressure monitoring program had to be conducted to confirm that this requirement was being met. This paper describes the water overpressure monitoring program on one of the exploration projects, presents the results of the monitoring, and discusses the challenges of carrying out this work in the middle of an arctic winter.

Jan 1, 2003

By R E. Otterness, M S. Stagg

The U. S. Bureau of Mines conducted 22 full-scale blasts to determine the effects of delay and explosive type on fragmentation. The shots were conducted over a period of 7 years in three limestone quarries and one granite quarry. Hole diameters, bench heights, and number of holes varied from 6.4- to 14-cm, 6.7- to 14-m, and 4- to 24-holes, respectively. Explosive performance and actual firing times were measured and screening was used to assess the fragmentation.

Jan 1, 1995

By Romel Villanueva, Juan Vasquez

We present the results of our field research on the variation of the density of the gassed explosives and their influence on the blasting results in the Peruvian mines: Yanacocha, Toquepala and Antamina. Currently, 90% of Peruvian mines uses gassed explosives, for their economic and technical benefits. But new practices and design criteria have had to be adopted, and the most important a careful control of the in-hole density, whose variation in the depth of the hole strongly affects the detonation process. For gassed explosives the density varies gradually according to the depth in the hole, due to the pressure on the bubbles by its own weight. The density at the bottom of the hole can reach critical values, which directly affects the start of the detonation in the booster zone with a high probability of nitrous fumes formation. On the other hand, density translates into the amount of explosive and energy available. Therefore, for the optimum performance of the explosive, the minimum and maximum values of the in-hole density must be determined. For the cases studied, the maximum in-hole density and the maximum charge length have been determined. When the charge length is greater than 7.0 m [ 23 ft.] special care must be taken with the cup density, which as a general rule should not exceed the value of 1.15 g/cm3 [71.8 lb/ft3] at the risk of losing the sensitivity at the bottom, also increasing the probability of nitrous fumes, bad fragmentation and finding intact explosive after blasting. In the large holes in Toquepala and Antamina mines, where the charge length can be greater than 9.0 m [29.53 ft]. If the cup density is greater than 1.15 g/cm3 [71.8 lb/ft3] the in-hole density can easily reach a high value of 1.30 g/cm3 [81.16 lb/ft3].

By Natalie Zeleznik, Brian Hawkins, David Bradley, Rachel Gooding, Patrick Wilson, Brian Somes, Kevin Wegman

"To perform a probabilistic risk assessment (PRA), a method of quantifying the risks associated withinfrequent high consequence events, consequence models that generate representative estimates of human health consequences for a wide variety of representative scenarios are commonly used. Criteria that suitable models must possess include: (1) input requirements necessary to generate large volumes ofprobabilistic simulations; (2) the capability to output injuries with the necessary details and resolution;(3) the ability to capture the variety of different scenarios inherent in an assessment; (4) acceptable cost and computational requirements; and (5) sufficient stakeholder buy-in for community acceptance."

Jan 1, 2017

By Robert Hopler

GEO. M. MOWBRAY’S REFRIGERATOR CAR FOR THE SAFE CONVEYANCE OF EXPLOSIVES. It is a fact well known to all miners who have used nitro-glycerin, or any of its adulterations, commonly known as dynamite, rendrock, Hercules’ powder, dualin, vigorite, etc., that when congealed, these compounds cannot be exploded, and in this congealed state — say at temperatures below 40° F. — they can be handled with no more danger than a box of soap or a can of lard. If, then, the atmosphere by which this class of explosives is surrounded, during transportation, be maintained below 40° F., explosion is practically annihilated. Therefore, I constructed a refrigerator car, with cells for every box of the explosive; and two years of railroad transportation confirms our ten years’ experience in teaming in wagons, that this class of explosives can be transported in perfect safety, as above described.

Jan 1, 2011

By Alejandro Rosario, Ricardo Dumuihual, Guillermo Silva, be nito Danial Valde, Carlos Scherpenisse

A monitoring campaign to record dynamic pressures generated by detonation of a single blasthole was implemented at Barrick Gold´s Pueblo Viejo Open Pit mine (PVDC), located in the Dominican Republic. Pressure amplitudes beyond the dynamic compressive strength of the electronic detonator´s capsules have the potential to damage these electronic devices, generating misfires along with all the associated risks and entailed safety implications. In most instances, misfires generated from high dynamic pressures are a direct consequence of drilling deviations resulting in blasthole distances smaller than originally designed. Tourmaline Crystal Sensors specifically designed for high dynamic pressure measurements in aqueous media were selected to address the challenge. These sensors are custom-made and require additional instrumentation for proper operation, including signal conditioners and recording equipment capable of capturing simultaneous events, both in their amplitude and frequency components. Field-testing comprised detonation of a single blasthole using current explosive loading practices along with an arrangement of sensors positioned within water-filled drillholes in a spiral configuration. Distances, explosive weights and all 23 dynamic pressure record amplitudes are included along with additional data regarding arrival time and P-Wave velocity estimations. As with typical vibration models, the Scaled Distance concept (D/W1/2) was used to construct an attenuation model relating Dynamic Pressure as a function of Distance (D) and explosive Weight (W). The resulting model, adjusted to a 95% statistical confidence limit (covering 100% of the recorded data) was used to generate a series of curves (Abacus) estimating dynamic pressure as a function of distance for different explosive charges. These curves, in association with permissible pressure limits defined at 50% (FOS = 2) of the dynamic pressure strength reported by manufacturers for both, the 1000bar (Al) and the 1400bar (Cu) capsules; allow for the determination of critical (safe) distances between blastholes. Tests were implemented to cover a variety of field scenarios, accounting for different rock mass types, qualities and water conditions; however, preliminary analysis indicate the convenience of developing a unique trend that considers said variability. This approach allowed construction of a single, simple, unambiguous and operationally applicable design tool to address entailed safety issues.

By William Gates, Gabe McClain, Thomas Pallua, Joe Schrank

The Tennessee Capitol Corridor connects the Cordell Hull Building (CHB) to the State Capitol, which isa 232-foot-by-124-foot (71 x 38 m) structure in Nashville that includes porticoes built from local massive limestone. This connection was affected by the Capitol Connector Pedestrian Tunnel (CCPT) project, which is part of the overall Cordell Hull State Office Building and Central Services Demolition, New Construction and Renovation Project (Cordell Hull Renovation Project). To construct this connection, the two existing elevator shafts and a new emergency stairwell in the State Capitol were extended down to anew lobby area—the elevators by about 50 feet (15.2 m) and the stairwell by about 60 feet (18.3 m). This lobby was connected to the CHB by a 435-foot-long (133 m) pedestrian tunnel. It was predicted that most of the tunnel would be excavated in a relatively strong limestone; therefore, considering the project features and constraints, drill-and-blast techniques were selected as the primary excavation method. Because of restrictions on blasting in urban areas and, more importantly, the proximity of this construction to national historic landmarks, blasting operations were extensively monitored to measure and correlate ground vibrations as peak particle velocity (PPV), frequency, and strain—these being the major factors that would impact the surrounding buildings. As a result, copious amounts of data were gathered and interpreted within a short time to estimate blasting parameters and optimize the subsequent blast rounds. To calculate the ground response factor, the scaled distance of each shot was compared to the ground vibration as PPV, generating a subsequent regression curve with an R2value of about 0.7. Using the best fit curve equation, the estimated ground response factor was about 150 for the best fit line. Other than some cases with relatively high (> 2 in./sec [51 mm/sec]) recorded PPV values, the blasting operation was successfully conducted as planned and the observed strain on the monitored buildings was very low, mainly within ±2 με (0.0002% elongation). (In general, the recorded PPV was lower than 2 in./sec at frequencies of more than 50 Hz.). The strain gauges at key locations (cold joints and old fractures) in the Capitol and on other critical structures demonstrated strain was insignificant in relationship to ground vibrations from the blasting operations. The apparently small vibration-induced strains were related to the massive limestone construction of the Capitol and ancillary buildings, as the induced strain plus the existing strain did not exceed the critical strain of the massive structures.

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 Tianrui Xu, Chaohong Liu, Bangqing Ding

The authors were responsible for a series of large scale multiple chamber charge blasts conducted in the granite mountain area for making construction space on the southeast sea coast in China during 1993-1996. This paper describes the blast design and damage control of one mountain blast 320m in length and 280m in width in the vicinity of two wharfs and a dam. In order to obtain better rock fragmentation and muckpile, the explosive charge should be well-distributed in the mountain. The charge pattern, therefore, was designed with mainly 5 rows of tunnel charge in regular terrain in combination with a chamber charge in irregular topography area and the maximum burden was limited to be less than 38m. In order to protect the dam and wharfs the firing sequence was carefully arranged in 29 intervals and the distance between different charges of the same delay to the dam or wharf was taken into account as an additional delay interval based on the difference of p-wave propagating times. The maximum charge fired in an interval was also limited to less than 34t explosives through dividing the larger charge by a stemming deck.

Jan 1, 1998

By Kyle Apple

The following is a case study of how LuckStone Corporation improved their blast monitoring and documentation program. A number of resources already at their disposal have been utilized to improve the body of data collected from each blast. The tools being used include GPS, aerial photos, and a user-friendly push button format excel spreadsheet. The data collected include product by product records of materials used, distances to all concerned neighbors, seismograph data, etc: The spreadsheet has been designed to perform an ongoing analysis of blasting trends. The program has been carried out at a corporate level and is in use by blasters at each location. This paper addresses the advantages and drawbacks of this program. It also addresses the ways in which the various tools were integrated, Discussed as well is the need for simplicity when bringing “new” technology to the field and the steps taken in familiarizing the end user to changes.

Jan 1, 2001

By Park Yun-Seok, Jung Seung-Won, Hwang Nam-Sun, Song Jin-hyuk, Kim Young-ho

This study proposes a new blasting vibration estimation formula that reflects the vibration reduction characteristics of electronic detonators, which are not considered in the current MOLIT blasting vibration estimation formula. Test blasts were conducted across six types of Korean open-pit blasting designs. The results of the test blasts showed that the K value for electronic detonators decreased by approximately 30% compared to electric detonators. Predicted Peak Particle Velocity (PPV) analysis indicated a reduction effect ranging from 30% to 31% across various types. By incorporating this reduction in the K value into the MOLIT blasting vibration estimation formula (K=200), a new electronic detonator blasting vibration estimation formula (K=140) was proposed. Using this new formula, the blasting damage range (R) was calculated under various vibration limits to evaluate constructability improvement. On average, the R value for electronic detonators decreased by about 17%, with significant reductions of around 41% observed for TYPE I under certain vibration limits. In conclusion, the adoption of electronic detonators in open-pit blasting operations improves blasting efficiency, reduces economic costs, and significantly enhances constructability. Electronic detonators have demonstrated superior performance in minimizing damage to safety facilities compared to traditional electric detonators, thereby proving their practicality and effectiveness in blasting operations.

Jan 21, 2025

I attended a funeral in West Monroe, Louisiana, for one of the best powder peddlers I’ve ever known. He started work in 1948 for Dixie Dynamite, a seismograph explosive distributor. His first job was as a truck driver, then magazine keeper and then sales re p re s e n t a t i v e . When Dixie Dynamite quit, he acted as an explosives sales agent for sometime before moving on to Kansas to be a sales rep for a distributor there. We called him the “ragin cajun” long before James Carville came on the national scene messing up things. While he was born in G e o rgia, he was a Cajun at heart. I don’t believe the old saying, “Build a better mousetrap and the world will beat a path to your door.” To me, the best products in the world need to be sold. Two examples of this are the Beta system for TV and the Apple Macintosh computers. Beta is the best system but VHS took over because the Beta people fell down on the selling job. Windows 98 is Macintosh ‘86 but again the engineers were not salesmen. Marion “Johnny” Johnson who was buried only about a half mile from his first magazine site proved that good selling is good citizenship. He could have sold any firstclass product, for he wouldn’t tolerate inferior items, and made a successful career of it, but he chose dynamite and the industry benefited from his talents.

Jan 1, 2004

By Alan Hooper

This paper and slide presentation is a brief rundown on what is probably the worst natural devastation I have ever witnessed. The epicenter of the quake that so violently shook Mexico City occurred 230 miles away near Mexico's west coast. The first calculation placed the quake at 7.8 on the Richter scale. This was later upgraded to 8.1. Each unit increase on the Richter scale indicates about a 30 fold increase in energy released. The quake was felt in much of Mexico and south Texas and damage occurred in many other Mexican cities. On the morning of September 19, 1985, at 7:18 A.M., the ground went into motion and shook for approximately 2 to 4 minutes. During this period most of the devastation occurred. At 7:38 P.M. the following day, the second quake hit and more buildings fell from this 7.5 quake. The ground in Mexico City moves like jello since it is a dry lake bed 7,350 feet above sea level.\

Jan 1, 1986

By Elliott Giles

"Measuring a blast’s performance based on the bucket fill time or “diggability” has always been achallenge due to the subjectivity generally involved. The diggability of a blast is often based onopinions and speculation without the data to properly support the claim. This paper focuses howthe blast design can impact diggability and how it can be properly measured."

Jan 1, 2016

By Robert Hopler

Although electrical instruments were being widely introduced into the study of seismic tremors, attempts to understand and quantify shocks from blasting continued to use rather primitive methods well into the 19th century.

Jan 1, 2007

By Steve Dillingham

PHYSICAL BLAST DATA Pattern Description All measurements related to the description of the physical blast pattern must be made with the mind-set that it has to tell a powerful factual story enabling a future accurate reconstruction of the event. A case has never been lost because too much factual information was available to assist investigators. An accurate physical description of the pattern must be provided based on the blaster’s observations of the pattern actually loaded. The blaster must measure the pattern size, depth, face heights, etc., recording only accurate results. All too often, a blaster records simple pattern sizes and information relayed to him or her from the driller, or from a phone call into the office the night before for powder pre-load inventory purposes. If a pattern was actually measured on the job site by the blaster to be 8.5 x 9.5’, it may, in fact, originally have been ordered at 9’x9’, 8’x9’, or 9’x l0’. In a claim situation, particularly flyrock, recording a “generalization” of what was loaded could result in an interpretation of a blaster’s negligence due to “not knowing or caring” what the actual pattern was, and not loading appropriately for conditions. It is important to remember that other documentation exists such as a drill log from a contract driller or mine records that may provide a different interpretation of the loaded pattern.

Jan 1, 2002

By James A. McGrath

"The predominant key word associated with all commercial blasting methods is “safety”. Safetyshould take precedent over all other aspects of the entire explosives industry which on a wholehas had an excellent track record as to number of injuries per unit of hours worked at all blastsites throughout our country."

Jan 1, 1999

By Dale Ramsey

Emulsion explosives have become the product of choice for many blasting applications and are not limited to just extreme wet hole conditions or special application environments as in the past. Today’s novel emulsion technology has evolved over many decades, allowing a great diversity of formulations, Emulsion explosives can be effectively designed to produce very high energies, cap sensitive high explosive cartridges to bulk blasting agents, with varying viscosities, stable VOD’s, excellent water resistance, long shelf life and sleep time. They are also conducive to the mixture of emulsion, An/F0 blends in varying proportions and are amenable to any type of sensitizer. The key to a stable, reliable and consistent emulsion formulation is the careful mixing of the internal phase, which consists of a solution of oxidizer salts suspended as microscopically fine droplets, with the surrounding continuous fuel phase. There are few blasting applications today where some form of an emulsion explosive cannot fit the application. In massive, hard rock, dense, tightly jointed and fine grained rock types, the emulsion explosives are the best choices in creating new fracture networks for good fragmentation with a few alternatives. In such environments, emulsions with expanded drill patterns often result in better economics than the use of straight AnLFo. This paper will cover emulsion formulations, sensitizing options, product testing, material handling, and blast optimization, Emulsion explosives characteristics have also proven to reduce adverse environmental effects such as noxious fumes, ground vibration, and airblast while still remaining cost effective.

Jan 1, 2000

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 Douglas R. Burns

In New England, an area of the country where 3 ½" holes are considered large diameter,we are starting to experiment with 5" and 6" holes. The results are excellent in some areas and poor in others. The geology of rock is the major consideration to account for the blasting results.

Jan 1, 1997