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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 L. M. Lopez, J. A. Sanchidrian

This work investigates the performance of some of the measurement techniques used in vibrations from blasting monitoring. Two tri-axial geophones with cases of different size, shape and mass were tested in a shaker table. The geophone cases were mounted in three different ways on a granite slab fixed to the plate of the shaker: freely placed, sandbagged, and anchored. A known horizontal periodic motion of constant amplitude, and frequency from 16 to 200 Hz, was applied to the slab. Two amplitude levels of 5 and 20 mm/s (0.2 and 0.79 in/s) were applied when the sensors were sandbagged or anchored and only 5 mm/s when no holding force was applied. The transmissibility of vibrations from the rock to the longitudinal geophone as function of the frequency (i.e. ratio of response of the geophone to the slab motion) has been obtained for each measuring condition tested. The transmissibility is considered a composition of the transmissibility of the rock-to-sensor coupling and the transmissibility of the sensor’s mechanics and electronics. The transmissibility of the coupling is obtained normalizing the total transmissibility with the transmissibility of the seismographs, obtained by a suitable test to which a coupling transmissibility of 1 is assigned. Geophone-to-rock coupling is a resonant phenomenon that may alter the amplitude of the measured waveforms by a factor of 1.2 to less than 0.6. The most accurate and precise measurements are obtained with geophones anchored to rock. On the contrary, freely placed or sandbagged sensors are non-predictable planting conditions that lead to high amplification or damping in most of the frequency band analyzed. It is also shown that existing acceleration criteria to select coupling methods do not necessary lead to good quality (accurate and precise) vibration data.

Jan 1, 2014

By Robert Hopler

RBH Note: At the time of this price list the handwriting was already on the wall regarding the ultimate breakup of the company under the Sherman Anti-Trust Act. The brand names Atlas and Hercules, noted on page 3 of this pricelist, would become the names of the new companies created from du Pont.

Jan 1, 2012

By R H. Stevenson

This paper deals with a new variation of the cast blasting technique, where-in the object is to cast the economic deposit out front under the overburden, while avoiding dilution from the floor material. To date, the technique has been successfully applied at two cement quarries in Iowa and at a granite quarry in Minnesota.

Jan 1, 1991

By Ravi Sahu, Kris Jeremiah

This paper aims to study the benefits of using Post Processed Kinematics(PPK) surveying methodology combined with Drone photogrammetry to achieve highly precise positioning (X, Y, Z) of drill holes based on the drill pattern and to highlight innovative workflow of transmitting the drill plan to smart drills for accurate drilling.

Feb 1, 2020

By Aiden Carey, Jim Kennedy

During December 2007, Lake Cowal Gold Mine located in New South Wales, Australia experienced a significant pit wall failure. The wall failure resulted in the deposition of a large quantity of saprolite consisting largely of clays and lake bed sediments to the bottom of the Phase 1 open pit mine. This wall failure ultimately buried two loaded blast patterns.

Jan 1, 2011

By M Sampara, W Comeau

The introduction of large-diameter holes to underground mining has made possible the development of new mining methods such as the Vertical Crater Retreat (V.C.R.) method. It is not only the safest underground excavation system but also provides mass production at a lower cost than any conventional mining method (1, 2, 3, 4, 5).

Jan 1, 1981

By Timothy D. Stark

Blasters are usually strictly liable for injury or damage caused by flyrock (trespassory invasion) and blast-induced vibrations (non-trespassory invasion). The application of strict liability to non-trespassory invasions has resulted in significant litigation that has hampered the use of blasting and the blasting industry. Stark (2002) proposes that blasters should not be held strictly liable for non-trespassory invasions but should be liable only if their conduct is proven to be negligent. This change in legal standard was proposed because improvements in blasting technology over the last thirty years allow blasting to be conducted without substantial risk of harm to property and thus the amount of harm imposed by a blast can be related to the level of care exercised by the blaster. It is anticipated that negligence standard will reduce the amount of litigation because a plaintiff will have a greater burden to overcome. To facilitate the acceptance of negligence standard by a court of law, this paper illustrates the application of the negligence and strict tort liability frameworks using actual cases in which a decision was rendered. It is evident from these cases that some of the successful claims under the strict liability framework would not have been successful, and probably not litigated, under a negligence framework, which could result in substantial cost savings to the blasting industry and consumers.

Jan 1, 2004

By Lazar Kricak, Zoran Teodorovis, Dragan Bogunovic

Scattering of delay interval around nominal value is an important issue in blasting practice. The scatter interval, as becomes wider, increases a probability of time delay overlapping adjacent blastholes. An excessive flyrock, ground vibrations, air blast and poor fragmentation are the symptoms for scattering related problems. Utilization of the short delays in the blastholes and longer delays on the surface are recommended solution to overcome mentioned problems. In contrast to global trends manifested through the application of electronic detonators and non-electric shock tube systems, revitalization of inexpensive electric detonators in combination with an accurate initiation system may be an acceptable solution. An extensive work was carried out at the Blasting Center Laboratory at the College of Mining and Geology, University of Belgrade, to develop a precise initiation system. As a result, Sequential Blasting Initiation System – Radio Frequency (SBIS-RF) was developed. It is expected that this system will increase blasting productivity, and reduce negative environmental impacts and total blasting costs.

Jan 1, 2008

By Nicholas Matthews, Vilem Petr

This project will report findings on the establishment of a new surface test site at the Colorado School of Mines Edgar Mine. Concerns over the blast effects on site neighbors prompted the study to be conducted. The current maximum charge weight of 20-lb was studied to ensure that all environmental effects were within the range prescribed by state and federal regulations. Geophone locations were surveyed using GPS and monitored using Instantel Minimate Plus instruments. Distances and orientation of measurement sites to the test site were varied according to the local geography and geology. Weather conditions were also observed and recorded during all tests. Neighbor complaints were recorded and taken into account during analysis. Current results show that the current charge limit results in a safety factor of over 200 for all blasting activities at the site. Data collection is ongoing and a review is to be conducted annually. These results will be presented in the future. Results are presented and discussed in the following paper. Copyright

Jan 1, 2010

By Jim Daley

This case history discusses a pre-split test conducted at BHP Mineralss Navajo Mine in Fruitland, New Mexico. The test was an extension of earlier pre-split testing conducted by Virgil Stachura of the U.S. Bureau of Mines in conjunction with Navajo Mine and WESCO Inc. which tested low-density product in 10.625 diameter holes.

Jan 1, 1996

By Italo Onederra, Miguel Araos

"In order to characterize non-ideal explosives, the explosives industry rely on unconfined velocity ofdetonation tests and where possible underwater pond tests. The information obtained from such tests isquite helpful, however it cannot tell us much about the dynamics of the detonation reaction process. The detonation process has been studied for ideal explosives and the reaction zone length have been measured. However, for non-ideal explosives, that type of information is not available. Therefore, the primary aim of this work was to capture the detonation process of a non-ideal explosive using high speed video camera to determine the zone length."

Jan 1, 2017

By N. Paley

An engineering project was undertaken at the Cominco Alaska Red Dog Mine to determine the extent that Semi-Autogenous Grinding (SAG) mill throughput could be increased by blasting differently. The Julius Kruttschnitt Mineral Research Center (JKMRC) blast fragmentation, jaw crusher, and SAG mill breakage models were used to relate changes in the blast design 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, JKMRC research had shown that it appeared possible to increase primary breakage by blasting to such an extent that SAG mill throughput could reach a plateau or even begin to decrease. Modeling was carried out on a range of blast pattern geometries and emulsion explosive blends to determine if a plateau existed and at what powder factor it would be reached. It was found that the relationship between powder factor and grinding throughput was nonlinear. Modeling was also used to compare the SAG mill throughput which could be expected from different emulsion explosive blends to determine which blends should be used in dry and wet holes to provide similar fragmentation. For heavy-ANFO mixtures, the highest modeled throughput was at a ratio of 30/70, with ratios on either side indicating lower throughput. For emulsion blends, the highest modeled throughput was at a ratio of 80/20; however, ratios from 80/20 to lOO/O were similar. Crusher product size distributions were obtained from belt cuts early in the analysis to confirm model predictions. At later stages, actual SAG mill throughput was compared to predicted. The economic benetit from the different blast designs was calculated by accounting for the reduction in recovery due to the higher throughput and the additional drilling and blasting costs. Increasing the powder factor by 150% from the 0.29kg/t {0.58lb/st] being used to 0.72kg/t { 1.44lb/st}, the maximum feasible with mine equipment, could provide a sign&ant net benefit of $3OWyr due to the increased concentrate production. However, because the relationship between throughput and recovery is affected by other factors which were not modeled, a more conservative approach was taken. The powder factor was instead increased by 50°h, providing 45% of the gain. This was possible because the relationship between powder factor and grinding throughput was nonlinear.

Jan 1, 2001

By Jonathan D. Aubertin

The unique nature of rock salt blasting is compared to traditional hard rock practices. Rock salt geomechanical nature is discussed in the context of rock blasting events. A cratering mechanism prevalent in soft rocks is presented and exemplified through a series of single hole blast tests performed in salt deposits.

Feb 1, 2020

By Sebastián Seria, Jorge Álvarez, Diego Cáceres

The capacity to break the rock into adequate size fragments and in a cost-effective way is one of the main challenges in large open pit copper mines in Chile. That capacity is often compromised by the accuracy of geological estimations and the resources allocated by the mine site to update those models, making the blasting design highly dependent on that input and in consequence, blasting results. Given these opportunities, having an alternative method to input estimated key geological parameters allows blast designers to modify their designs and apply the appropriate energy to achieve the desired results. By using measurement-while-drilling data from boreholes and a few samples of actual, widespread, hardness measurements on site, we can deliver an updated cost-effective hardness estimation that is used as an input to improve the blasting design and its results on fragmentation. This estimation is delivered as a hardness interval – often in MPa units- related to the position of actual drilling measurements. In addition, having a sufficiently large drilling dataset allows us to predict hardness in new, undrilled areas near already measured boreholes, serving as a prior estimation available before pattern design. The use of these estimations, applied to several copper mines in Chile, allow us to more accurately determine explosive amounts and borehole drilling, which directly contributes to more productivity and efficiency in mine site operations. The results are often related to narrowing the gap for fragmentation results, even so, in some cases that will be related to direct savings in Drilling & Blasting process in a range 5-10% of the budget, due to powder factor changes.

Jan 26, 2026

By Tom Watts

This paper will focus on the design, manufacture and use of pump safety systems on MMUs (Mobile Manufacturing Units – Bulk Trucks) with progressive cavity pumps. The practice of pumping bulk blasting agents is highly regulated and the explosives manufactures have done an excellent job of hazard and operability studies allowing criteria to be established for the safe pumping.

Jan 1, 2009

By C. Zuniga, S. Combrinck, C. Peters

Agnico Eagle Gold have partnered with Enaex Australia at their Fosterville gold mine to leverage a combination of drill and blast technologies to optimise underground development mining. The mine is the first site globally to collaboratively develop and trial Enaex SWIFT electronic development detonators, which utilise a novel approach to the user interface, simplifying implementation and enabling the benefits of electronic initiation without the complexity of a conventional system. This has been combined with the use of a Sandvik 422i smart jumbo, and the Enaex underground emulsion charging unit with the capability to tailor the delivery of explosives as required and report on a hole-by-hole basis. The combination of these technologies enables full engineering oversight of the development cycle, in turn enabling optimisation of this process in a historically conservative application. The methodology for leveraging these technologies is to bore a controlled and defined blast pattern through using a smart jumbo, load the blast holes utilising lace loading to deliver a desired quantity of ammonium nitrate emulsion per hole, with the ability to reduce chargeweight for perimeter control, and utilising Enaex SWIFT electronic detonators with flexible template type pre-defined delays to initiate the blast holes. Subsequent to firing and excavation the performance of the blast in fragmentation, advance efficiency, and overbreak and underbreak is measured and reviewed. This is then used to optimise the development cycle and apply to other parts of the mine.

Feb 6, 2023

By NA NA

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Feb 6, 2023

By Cristian Castro, Patricio Gomez, Jason Furtney, Augusto Lucarelli

Understanding the effect of blast-induced damage on wall stability is critical to safe and economical operation of a large open pit mine. In this paper, a numerical modeling methodology is used to investigate damage to rock at distances of greater than 10 m (30 ft) from a blast. Two applications of the model are demonstrated. First, the method is applied at a zinc mine to investigate the effects of pit blasting on underground stopes. The model predictions are compared with the scaled distance formula. Next, the model is used to investigate a common problem in which unfavorable jointing creates a rock wedge on the bench above a blast. The numerical predictions of wedge stability are compared to the wedge energy model described by Wong & Pang (1992).

By Cristian Castro, Patricio Gomez, Jason Furtney, Augusto Lucarelli

Understanding the effect of blast-induced damage on wall stability is critical to safe and economical operation of a large open pit mine. In this paper, a numerical modeling methodology is used to investigate damage to rock at distances of greater than 10 m (30 ft) from a blast. Two applications of the model are demonstrated. First, the method is applied at a zinc mine to investigate the effects of pit blasting on underground stopes. The model predictions are compared with the scaled distance formula. Next, the model is used to investigate a common problem in which unfavorable jointing creates a rock wedge on the bench above a blast. The numerical predictions of wedge stability are compared to the wedge energy model described by Wong & Pang (1992).

Feb 1, 2020