Search Documents

By Robert B. Hopler

"The story of packaged explosives begins with the use of black powder (also called gunpowder) in mining. Although discovered in the 13th century, it was not until 1627 that the first records of use in mining is recorded. It took until the early 1800's before its use began in underground coal. Althougha free-running, granular material, its recommended (and safest) manner of use was for the miner to pour it into ready-made or onsite formed paper bags prior to insertion into the borehole. This was absolutely necessary in horizontal or upward-slanting holes."

Jan 1, 1991

By C. T. Aimone-Martin, B. M. Meins

This paper compares response of large urban structures to small charge weight, ultra-high frequency rock blast excitation from contiguous excavation to that of houses to more distant, larger charge weight blasts. Time correlated responses were measured for both structures at the corners, top and bottom of the structures as well as in the foundation rock below the bottom. The comparison allowed the following conclusions: Close-in blasting with direct rock to building wave transmission imposes short wave length excitation which fails to excite the large, massive structures synchronously whereas the more distant blasts do synchronously excite houses. The larger urban structures respond predominantly in wave transmission mode where there is a noticeable difference in time, frequency, phase and amplitude of motions measured at the bottom and top corners of the structure. Excitation motions along the base of the larger urban structures also differs in time, frequency, phase and ampli-tude. The short wave length of the excitation motions leads to attenuation of the peak particle veloc-ity along the base. Ultra-high excitation frequencies, which are much higher than the expected struc-tural natural frequencies, lead to deamplification for all events for the large urban structures.

Jan 1, 2018

By C W. "Mickey" Bradley

Thunder strikes terror in the hearts of man and has since the advent of time. We all fear the unknown; even the Greeks created a god, THOR, to be responsible for the thunder and rain. Thunder, by itself, can't hurt anyone; it is simply hot air moving very fast. Thunder, however, is caused by lightning and lightning is what we need to fear and rightfully so. Annually, lightning kills hundreds of Americans, injures another 2,000, damages or destroys approximately 30,000 structures, 1 starts thousands of forest fires and strikes mine properties over 100,000 times.

Jan 1, 1992

By B de Raadt

After discussing mechanisms of collapse for the explosive demolition of towers in general and cooling towers in particular, author comments upon a blasting operation in which four cooling towers were involved. The intention of this paper is to present reliable parameters, generally valid for the explosive demolition of reinforced concrete cooling towers.

Jan 1, 1978

By A. Ribeiro

The effective utilization of resources and process optimization play a crucial role in the sustaining and growth of overall businesses. This principle holds true in the mining sector, where particular attention is required during the comminution steps. This necessity arises from the fact that mining operations often consume substantial amounts of energy in mineral processing. Therefore, it becomes imperative to thoroughly study the integration of comminution steps. In many instances, an approach to be studied is the operation commencing with the drill and blast phase and culminating in the grinding product process. Nevertheless, establishing an optimal integration between drill and blast operations and the grinding phase is a complex undertaking due to the direct influence of rock characteristics on this process. And in many cases, the complexity and variability of such physical characteristics makes mining operations to ignore such influence. Consequently, Enaex Mining Technical Solutions (EMTS), in collaboration with Lundin Mining's Chapada Mine engineering team, and with the assistance of Hatch Consulting and Technology, has undertaken a comprehensive study aimed at enhancing mill throughput at the Chapada operation. The basis of this study lies in characterizing the rock masses present in the Chapada Mine to gain a deep understanding of the material that needs to be comminuted. Subsequently, the mineral processing team determined the most suitable size distribution for the Run-of-Mine (ROM) material. With this information, the drilling and blasting team built a site-specific blast fragmentation model, able to simulate various blast design scenarios. This approach enabled to optimize the utilization of available drilling and blasting resources while striving to achieve the optimum ROM characteristics. Since 2021, the Mine to Mill methodology has been progressively implemented at the Chapada Mine. As a result, the blasting engineering team now utilizes the blast plans generated by the fragmentation model simulations as a foundation for designing blast plans that align with the operational and financial capacities of the mine. Overall, it was predicted that this implementation could lead to an average increase in mill throughput of 13-22 % depending on blend feed, once all recommendations are implemented. Even with partial implementation, plant results demonstrate a 5 % increase compared to the period before the Mineto-Mill project, without any coarsening of the associated grinding product size.

Jan 1, 2024

By Dworzak, Andrzej Biessikirski, Jozef Pyra

During the detonation process 20-30% of the energy is being consumed only on the quarrying pro-cess. The remaining amount of the energy generates harmful effects such as: shock wave, acoustic wave, fly rocks and ground vibrations. The ground vibrations effect is the most dangerous especially to structures which are situated nearby an open pit mine.

Jan 1, 2015

By Stephen P. Case, Stephen Castellucci, William Parsons

In this paper, the authors present a step-by-step discussion of dimension stone production at a New England granite quarry. The quarry mines a rare pink granite which is used for facings and panels in the construction of high rise buildings around the world. The discussion includes geological considerations, block layout, drilling, explosives loading, block handling, and mobile equipment utilization.

Jan 1, 1990

By Radhe Krishna, Mutale William Chanda, Timothy Mwale

Blasting as a process is the emplacement of industrial explosives into blast holes suitably located to a free surface and detonated. Every blast hole containing a certain amount of explosive charge undergoes impulsive loading when detonated and results in the dynamic transfer of a powerful shock wave to the surrounding rock. It is the shock wave that brings about rock breakage when the tensile stress produced upon reflecting from the change in material density or free face overcomes that of rock material tensile strength. However, this shock wave comes along with unwanted destructive consequences such as damage to remaining rock, ground vibration, noise and fly rock. The above mentioned consequences pose a great threat to the Community of Wusakile, Kitwe as Mopani Copper Mines Plc wishes to increase its production by expanding the pit towards the community that lies within 150 m (164 yd) from the pit rim. As a requirement from the Zambia Environmental Management Agency (ZEMA), all blasting operations close to the community must maintain at least below the maximum vibration threshold of 10 mm/s (0.3937 in/s) PPV-Peak Particle Velocity or else risk closure of the mine (AMC,2009). In order to satisfy the above statement, a good understanding of explosives is required. This paper therefore presents the phenomenology of rock breakage by explosives with much emphasis on electronic blasting and how best this process can be controlled in densely populated communities. Factors affecting maximum projection distance such as, size of the fragment, shape of the fragment, angle of projection, the state of confinement of an explosive charge, were also studied. In addition, design faults, deviation in implementation and unforeseen geological conditions were also considered. The paper discusses the above facts based on research.

Jan 1, 2015

By Ken Tunnel

In the spring of 2005, the Lake Superior Chapter of the ISEE invited me to speak about raw materials used for blasting, anhydrous ammonia and the effect of this important feedstock on the cost of ammonium nitrate.The invitation was extended because our company is involved in trading ammonia and the production of ammonium nitrate. In a response to a request to update that presentation, it struck me how events such as hurricanes Katrina and Rita can change the landscape of our businesses.

Jan 1, 2007

By Robert A. Cummings, Francis S. Kendorski, Charles H. Dowding

During the summer of 1980, a field project was carried out to determine the stability of the beautiful and dramatic natural limestone pinnacles (locally termed "Hoodoos") at Bryce Canyon National Park, Utah, when subjected to ground motions and airblasts resulting from proposed strip coal mine blasting. The concern arose from environmental considerations associated with the proposed development of a large coal strip mine which would approach within 4 miles of the park. The pinnacles range up to 150 ft in height and are quite slender, producing a fragile appearance. The remoteness and ruggedness of the area required a field camp, and 4-wheel drive vehicles, helicopters, and snowcats for support. Portable magazines were necessary to store the more than 7 tons of blasting agents and explosives required. In conducting the blasting, great attention was paid to environmental impacts. In the field, a target pinnacle was selected and instrumented with mechanical strain gages, and research seismographs that required helicopter placement.

Jan 1, 1982

By Gary Anderson, J. P. Remi Proulx

Rio Tinto’s Colowyo Coal Mine produces 2.1 million tons per year in northwest Colorado. Colowyo uses the terrace mining method to recover up to seven coal seams ranging in thickness from 5 to 20 feet. Coal recovery in the 6 foot thick high grade C-seam has recently been challenged due to large variations in the pitch and roll of the seam. As well, some coal damage was seen due to an increased thickness of the overburden consisting of a hard sandstone channel.

Jan 1, 2012

By Julia Creasey, Natalie Hodgson, Claire Ward, Craig Davies, Helen Sarginson

"Emulsion explosive producers are attempting to lower the cost of emulsion production by using lowquality ammonium nitrate in emulsion formulations. Low quality ammonium nitrate contains additivessuch as anti-caking agents and crystal modifiers which contaminate the emulsions causing instability. This presents a need for an effective emulsifier that will maintain emulsion stability under thesechallenging conditions."

Jan 1, 2017

By Thierry Bernard

Considering rock fragmentation by explosive as the ultimate goal in mines and quarries, vibrations are definitely one of the main drawbacks faced by the Industry. If we can accurately predict vibrations level and frequencies, taking into account the whole set of the involved parameters, this will bring a major benefit to each of us, in our daily production process optimization effort. The model presented in this paper answers to this need thanks to a "holistic" approach of the vibration mechanism. By holistic, we mean that we approach the vibration effect (wave propagation) as a whole, by understanding all of the mechanisms that contributes to the process and comprehending how they are connected.

Jan 1, 2009

By Dale Preece, Mike Stern, Steve Piercey, Ayman Tawadrous, GC Zhao

The McArthur River uranium mine in Saskatchewan, Canada is the world’s largest high-grade uranium mine. It has employed a freeze-wall system consisting of multiple freeze pipes to control the large quantities of water encountered during mining.

Jan 1, 2011

By Andrew F. McKown

This paper will discuss the mechanisms of potential damage from close-in construction blasting, concentrating on two mechanisms: elastic ground vibrations and non-elastic (permanent) ground deformations. The latter will be shown to be the most dangerous for close-in blasting. With respect to elastic ground vibrations, discussion will center on the differences in vibration frequencies and impacts between typical close-in construction blasting and typical mine and quarry blasts, and how using vibration criteria derived for residential structures near mines can lead to very conservative criteria for close-in construction blasting. The effects of high frequency vibrations seen in close-in blasting will be commented on. Factors affecting the magnitude of ground motions will be discussed. Simple, practical techniques will be presented to minimize the potential for damage from close-in blasting, by minimizing the potential for rock block movement or ground heave. Case histories will be presented to illustrate some of the techniques discussed, and give examples of successful close-in blasting projects.

Jan 1, 1991

By AJ Rorke

Blasting trials using Daveytronic Electronic Delay Detonator systems (EDD’s) were conducted at the Alpha Ferro Quany (Pretoria) and the Eikeboom Colliery near Witbank in November 1999. The objectives of the trials were to determine the influence of accurate hole firing on rock fragmentation, blast-induced vibration and blast throw. This paper provides an outline of the trials and an analysis of the results. The results were compared with a normal shock tube initiation system. Fragmentation was measured using video-imaging techniques at the hard rock Ferro Quarry for one conventional shock tube blast and two EDD blasts. No significant difference was measured in the fragmentation between the shock tube blast and the two electronic detonator blasts. Joint planes mostly defme the fragments at Ferro Quarry. The fragment sizing was therefore controlled mainly by the rock structure and the blast timing appeared to have no influence. Vibration measurements made at Ferro Quarry indicate that electronic detonators have a marked effect on vibration frequencies compared to shock tube systems. The more accurate detonators resulted in a narrower f+equency band at lower amplitude with similar timing. By modifying the blast timing, the dominant frequencies were changed. The electronic detonators had a significant positive influence, therefore on blast vibration and its control. The timing scatter measured from the shock tube blast was considerable, with measured inhole detonator scatter at 48 ms over a sample of 19 units. Surface delay periods less than 42 ms would therefore not be able to provide effective sequential firing. The scatter of the Daveytronic units was below the 2 ms resolution of the high-speed camera used to film the blasts. Reliable sequential firing, even at very short delay intervals was considered the main reason for notable improved throw in an overburden blast at Eikeboom Colliery. Blast throw was improved by 25% for the test blast.

Jan 1, 2000

By Greg Rappard, Francois Holowenczak, James Rickard

The King George V (KGV) Shaft forms part of MTR Corporation Limited (MTRCL) Works Contract 703 extension of the underground West Island Line on Hong Kong Island. The Shaft and the associated adit was the sole access to excavate the running tunnels. Originally during the Detailed Design stage, it was concluded that blasting was not feasible at the KGV Shaft due to the close proximity of sensitive receivers in the form of residential buildings, electrical cables and hospitals. As a result, the Contractor planned to excavate the Shaft using mechanical means with a programme time of seven months. The Contractor appointed a Sub-contractor to analyse the feasibility of excavating the Shaft by blasting. The Sub-contractor reviewed the proposal and recommended the use of an innovative blasting technique that had never been previously employed in Hong Kong. The Sub-contractor recommended the Shaft be blasted using DetNet electronic delay detonator technology, manufactured by AEL Mining Services in South Africa, with an initial 1.5m depth of water ballast covering the blast face. The electronic delay detonators provided initiation accuracy to ensure there would be no overlap between sequentially detonating blastholes. The water ballast makes use of the effect of energy lost through the shock front causing the water to break up into droplets creating a spray dome resulting in the attenuation of the energy imparted into the surrounding rock mass. Various tests have demonstrated that both the maximum overpressure and impulse density are significantly reduced when water of a minimum depth is in direct contact with detonating explosives. This innovative blasting technique reduced the excavation programme by three months, saved HK$5 million in direct costs and totally mitigated the impacts on the public and other stakeholders nearby the KGV Shaft. Peak Particle Velocities (vibrations) rarely exceeded 2-3mm/sec (0.08-0.12in/sec) at a distance of 30-40m (98-131ft) from the blast location and air overpressure levels were reduced below the Hong Kong target level of 120dBL. In total, 24 blasts were fired with an average advance of 1.6m (5.25ft) with an average powder factor of 2.03kg/m3 (0.127lb/ft3) to 1.84 kg/m3 (0.114lb/ft3). The initiation pattern had 5ms between sequentially detonating blastholes and 20ms between adjoining rings.

Jan 1, 2013

By Saeed Karimifard, Saman Nouranian, Shahram Tafazoli, Bahram Sameti, Frank Chu, Caitlin McKinnon, Tetiana Konstantynivska, Glen Turner

We propose a particle size analysis solution for haul trucks that does not impact current operational workflows. Using artificial intelligence (AI) and 3D imaging technology, our solution reliably localizes and identifies haul trucks as they drive by, then accurately calculates the particle size distribution of the visible material in each truck load. In this paper, we identify the challenges of designing and implementing the proposed solution and explain the strategies we employ to overcome these. We also discuss a method for boulder detection that leverages the existing deep learning architecture to significantly reduce crusher downtime caused by oversized rocks

Feb 1, 2020

By M. Szumny, P. Mertuszka, K. Fuławka

Mining-induced seismicity is one of the adverse side effects of mining with the use of explosives at great depths. Disturbance of the primary stress state by the development of the network of excavations combined with the continuous generation of dynamic loads by the detonation of explosives in mining faces has a negative impact on the level of safety of crew and machines. To ensure the stability of excavations it is necessary to identify in detail the nature of the seismic hazard by means of continuous seismic measurements. Unfortunately, the technologies used so far are characterized by high costs of installation and further maintenance, which clearly limits the possibility of using a large number of stations in a small area. A breakthrough in this matter may be the technology of microelectromechanical systems, which is several times cheaper than standard solutions used in mining seismology. This technology, with the appropriate configuration of devices, can be successfully used to monitor dynamic phenomena generated by mining activities. As part of this study, the assumptions and configurations of a prototype 42-channel accelerometer network using MEMS technology have been presented. The network was installed in the Lubin underground copper mine in Poland in a seismically active area, where multi-face destress blasting are conducted regularly. As a result, 14 tri-axial accelerometers were installed in the immediate vicinity of the active mining front at a distance of about 1,000–4,000 ft (300–1,200 meters) from the closest faces. Highfrequency recordings are collected based on algorithms that trigger the system when the Peak Particle Acceleration set value is exceeded or on the basis of a manual external triggering device connected to the blasting machine. During the measurement period, several high-energy seismic tremors and several dozen of waveforms generated by blasting were recorded. The obtained results are the basis for assessing the effectiveness of the destressing measures and for the analysis of geomechanical risk based on periodic analysis of the velocity of seismic wave propagation

Jan 1, 2024

By Alejandro Ferrada Vergara, María Jesús Barros Godoy

The need for a basic method for selecting explosives based on rock mass or intact rock properties for mining and construction arises from the limited consideration given to these factors when choosing among products and also an implicit overestimation of the explosive power to fragment the rock. This study highlights the importance of evaluating different properties such as rock strength, deformation, fracturing, detonation velocity and energy release when selecting explosives. The concept of characteristic impedance, which considers rock strength against shock waves generated by explosive detonation, is introduced. Understanding this concept is crucial for assessing explosive behavior according to various rock types. The study concludes with a practical guide table that categorizes rock properties and provides recommendations for selecting explosives based on rock mass and rock properties. However, it is important to consider other relevant factors, such as the presence of water or nearby instabilities, which can influence the final choice of explosives.

Jan 21, 2025