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By J. A. Sanchidrián, P. Segarra, S. Gómez

Blasting is a common activity in mining that can cause significant damage in the remaining rock mass. The most commonly used method for predicting vibrations is the Swedish or Holmberg-Persson approach. It is a simple and fast method that uses empirical formulation to estimate the vibration levels based on the explosive charge weight, distance to the source, and other parameters. However, it has limited accuracy and does not consider the effect of free surfaces or other boundary conditions. On the other hand, recently developed methods as the full-field solution (FFS) can provide more accurate predictions of vibrations due to excitations provoked by cylindrical columns of explosive, but the inclusion of free surfaces in analytical methods is a challenging problem. This paper presents a new approach that includes free surfaces in the FFS to predict vibrations analytically in the near-field. The main obstacle to including free surfaces in the FFS was the belief that the solution was non-decoupleable in P- and SV-waves separately. The Heelan's approach was previously used to decouple them, but it only provides valid radiation patterns in the far-field and does not account for intrinsic attenuation. In this paper, we address this problem successfully, allowing for the inclusion of free surfaces in the FFS.

Jan 1, 2024

By Francisco Sena Leite, Vincius Miranda, PhD Machado Leite, PhD Pinto, Raquel Carvalhinha, Alexandre Julio, Dorival de Carvalho

Rock blasting, in particularly the drilling process, is one of the first processes in the stage of rock fragmentation and plays a fundamental role by influencing all the following stages. Given its importance, some proposals to optimize this process have been presented over the last few years. These proposals, while having different approaches, aim (in a large part) to minimize the costs of drilling and blasting respecting the limits of fragmentation required by primary crushing. Reviewing some recent articles leads us to an enriching experience, since the authors of these articles clearly model the problem, but do not address the mathematical solution of these models, which in turn, given their non-linear nature, have no directly and easy solution. Simple and even robust optimizers present in the market show different results and often do not converge to a single solution. To address this problem, an adapted gradient heuristicbased model was developed to try to find optimum values. Heuristics search for values of stemming, subdrilling, burden and spacing that minimize the costs of blasting and drilling. This search, which by the nature of the heuristic moves the solution in the direction of the gradient with maximum decrease to find optimal solution, found values that in turn, when compared with values presented by market solutions not only equaled them as, in some situations, even improved the proposed solution. The algorithm was tested and validated on the field, and although the results have already been presented in papers published in the last year by the authors of this paper, it is now presented with its mathematical formulation and comparison with the other solutions. This approach is expected to be able to improve (and even demystify) the process of pattern expansion and be the basis for future work in the continuation of the optimization process.

Jan 1, 2019

By Samir Garcia, Alain Mestanza

This technical work was carried out in an open pit copper mining unit, located in central Peru, which has a daily production of 440 thousand tons per day. Currently the pit consists of three mining phases, however, in phase 05 north, there is the construction of a shaft with a height of 375 meters, the function of this structure is to collect and drain the water coming from the pit, there is the importance of preserving its stability and keeping it operational, guaranteeing the sustainability of the operation. For this, a controlled blasting plan was developed that goes from level 4530 to level 4455 to place the central well on a bench, reactivating the pools.

Jan 21, 2025

By Daniel Johansson, Markus Danielsson, Håkan Schunnesson

In sublevel caving, blasted material flows gravitationally into the drawpoint from above in a periodical manner. This type of flow behavior entails muck pile conditions that are variable along the course of extraction. The effect of this variability on the LHD (Load-Haul-Dump) operation in terms of loading efficiency and ability to undermine the blasted ring is not fully understood as of today. This paper presents results from a field test in LKABs Malmberget mine in Sweden, where the influence of fragmentation on the loading operation has been studied in detail. Drawpoint filming was conducted for extraction of two rings equivalent of roughly 10000 metric tons (~9842 long tons) of material each. The analysis includes fragmentation measurements, muck pile classification, and general estimations in terms of loadability. Further, an evaluation of LHD machines from two different manufacturers was conducted to identify and highlight differences. The results show that fragmentation, muck pile compactness, and flow characteristics are all interdependent. Flow disturbances and the subsequent loading of compacted fine material in the back of the ring have been identified as the main reason for occurring problems and prolonged digging times. However, the ability to sufficiently undermine the blasted ring has been identified to primarily depend on digging depth which is only observed to be high during flow disturbances. An absence of flow disturbances seem to promote high loading efficiency but simultaneously limit the maximum digging depth. A mid-range particle size distribution with a low amount of fines has proven beneficial for overall loading efficiency. The various LHDs employed showed significant variations in terms of ability to handle difficult loading situations (e.g. compactness, boulders, etc.).

Jan 1, 2018

Controlled Blasting, Inc. (CBI) located in Norcross, Georgia recently teamed with the Dekalb county fire marshals office to stage a mock disaster to test new trainees of Community Emergency Response Team (CERT). It as an interesting example in which industry can help out the community and government through the use of explosives.

Jan 1, 2010

By Thad M. Jones

This paper considers the sampling, digitizing and reconstruction of seismic signals. A sampling frequency range is proposed and a minimum limit is suggested. Digitizing precision criteria for both peak velocity and analysis applications are given. Several methods for reconstructing signals from sampled data are presented.

Jan 1, 1985

By Thomas Kovalchuk, Kenneth Eltschlager, William Shuss

In April of 2000, two adults and their newborn infant, were poisoned by carbon monoxide in their home and received medical treatment at a Pennsylvania hospital. Carboxyhemoglobin levels were; child - 3 1%, father - 28Oh, and mother - 17%. Initially the furnace was blamed but after further review, blasting at a nearby coal mine was determined to be the source. All other sources of carbon monoxide were ruled out. The blasting was about 400 feet from the house. The conditions that led to the migration of gas include: the blasts were highly confined, the geologic structure contained fractures that served as conduits for the carbon monoxide to reach a hand-dug well outside the house, and the well was atmospherically connected to the basement floor drains.

Jan 1, 2001

By Gloria Contreras

The study aims to optimize the density of holes per tunnel section. The energy distribution, the one with the highest density, is used in the center of the diagram and is distributed homogeneously towards the contours with the lowest energies up to the contours to produce a perimeter control.

Feb 1, 2020

By Roy McKinstry

In March of 2001, Barrick Goldstrike became the first surface gold operation in North America to evaluate the advantages of electronic detonators. A detailed study was conducted to quantify the benefits of the use of electronic detonators to the downstream excavation, crushing and ore processing operations. The following methods were used to quantify blast performance: High speed film and video monitoring Firing time and rock response analysis of the high-speed films Digital fragmentation analysis of the post blast muckpile Vibration waveform analysis (including Fast Fourier Transforms and seed waveform modeling) Excavator performance quantification Crusher, SAG mill and ball mill performance evaluation Ore recovery analysis Cost/benefit analysis

Jan 1, 2002

By Joshua Hofman, Braden Lusk, Erin Morris

Explosions in urban environments, whether of accidental or malicious cause, often result in extensive injuries, loss of life, and property damage. The ability to predict the damage inflicted by these events is highly sought after; in order to predict damage, the behavior of blast waves within these environments must be quantified and understood. Urban constructs such as buildings and roadway intersections affect the natural propagation of a blast wave, intensifying or rarefying the wave depending on their arrangement.

Jan 1, 2012

By Blair Jackson, Tjaart Louw

Martha Mine, owned by Newmont Mining, Australia appointed Macmahon Contractors (NZ) Ltd as the mining contractor to drill, blast, and crush and convey ore for processing, followed by construction of a tails dam facility from the waste material. The open pit is located 140km(90miles) south east of Auckland, New Zealand in the middle of the township of Waihi (the main street of the town with a population of 3,500 is 90m from the perimeter of the open pit mine). Mining must proceed at 325,000m3 (of which involves blasting approximately 11,000 holes per month, in order to ensure continued ore supply.

Jan 1, 2003

By Bethany Witter, Dyno Nobel

In the past decades, a technological explosion has caused generational shifts. First, millennials experienced a technological shift to computers and cellphones. Next, Generation Z experienced a shift to smart phones and social media. These two generations are immersed in technology and are accustomed to constant connectivity. How do the extractive and construction industries gain the interest of younger generations and integrate them into the industry?

Feb 1, 2020

By Bethany Witter

In the past decades, a technological explosion has caused generational shifts. First, millennials experienced a technological shift to computers and cellphones. Next, Generation Z experienced a shift to smart phones and social media. These two generations are immersed in technology and are accustomed to constant connectivity. How do the extractive and construction industries gain the interest of younger generations and integrate them into the industry? The Virginia Tech Student Chapter of the International Society of Explosives Engineers handled this same issue with its recruitment efforts and event planning from 2017-2019. The first critical component of integrating Generation Z college students into the extractive industries is clear and frequent communication via email. Next, Generation Z often values the motivation behind work when choosing a career, so advertising technological advancements, benefits, and ways people can contribute to improving the industry also helps attract young generations. Similarly, advertising opportunities for people to work outside with their hands, travel, and secure stable careers can attract students. At Virginia Tech, the most effective way to attract and maintain the interest of students in extractive industries is to put the students in the field. Field trips to mines and factories experienced the most stable attendance and highest survey reviews of all other chapter events. Guest presentations from industry professionals were often well attended, but attendance tapered off as the academic year progressed and students grew busier. Periodic trips throughout the year maintained student engagement and often supplemented their curriculum. The student chapter was relatively successful in attracting students, but it struggled to maintain attendance levels in the latter portion of the academic year. In the future, the industry can increase its recruitment of Generation Z and Millennials into the workforce by working more closely with university programs to provide resources and opportunities for hands-on experiences for students.

By P. R. Mohanty, Kaushik Dey

Blast-induced tunnel overbreak prediction in the past has been based on peak particle velocity measured far from the blast site with necessary extrapolation. This has often resulted in suggesting higher damage threshold levels of Acceleration/PPV for overbreak prediction (Bogdanhoff, 1995, Holmberg and Persson, 1997, Murthy and Dey, 2002). These, site-specific far-field blast vibration studies, have also revealed that predicted PPV levels for overbreak could lie in the range of 700-5000 mm/s, an extremely wide range to generalize. Experimental blasts were conducted, in an underground metal mine located in eastern India, with an objective to study the level of acceleration /peak particle velocity generated in tunnel blasting. Accelerometers and tri-axial geophones with measuring ranges upto 500 g, 254 mm/s respectively, were mounted on the tunnel floor close to the blast face, with sensor distances varying from 15.25m to 36.10m. Due to straight faces the measuring distance could not be reduced further anticipating, in particular, cable damage. The equipment used was of M/s Instantel Inc., Canada. The blast pattern used was burn cut with large dia relief holes providing the required free face. The blast hole depth was 1.8m. Tunnel overbreak was measured using a telescopic offset rod fabricated at Indian School of Mines, Dhanbad, India.

Jan 1, 2004

By Andrew Wetherelt

Blast vibrations are of paramount importance in a society where ever increasing development is putting more stringent requirements on their control. Increasing civil development and more complex extraction scenarios make the trade off between proficient vibration control and productivity difficult to ascertain. Historically, reduction of induced vibrations levels was achieved through a reduction of MIC’s leading to smaller but more frequent blasts in order to meet extraction targets.

Jan 1, 2007

By Felipe França Sitonio

Parameter’s control of explosives used in blasting operations have become more relevant over the years, bringing a better understanding of detonation performance. Giving into consideration that bulk emulsion density’s variation reflects directly on blasting results due to its importance in product sensitivity and velocity of detonation (VOD), blast designs are conducted assuming that cup density measurements are reliable and explosives gassing agents will perform as per specifications. Nevertheless, confinement conditions in boreholes like temperature, presence of water and surrounding circumstances of rock mass are often neglected on predictive modelling and off-site measurements. This paper describes the assembly of a device equipped with pressure sensors and its utilization in confined boreholes of an open pit mining operation, aiming to obtain in situ monitoring of density variation in several explosive columns. After we developed a software to get and process data of a hardware prototype and the device functionality was validated in water, oil and quarry mining experimental trials, 7 of 291 boreholes in a gold mine operation were chosen to be monitored with two probes each, placed at the top and at the bottom of the explosive column profile. The results obtained enabled a comparison between the bulk emulsion density variation when acting in different environments, since we selected boreholes with diameter of 101.6 mm (4 in) and 139.7 mm (5.5 in) and some with presence of water. Besides the increase of explosive density with depth related to hydrostatic pressure increase, we found an overall error of 6% in cup density measurements when compared with sensors placed at the bottom of boreholes and 2% when compared with sensors placed at the top of explosive column. These findings provide detailed insights into how bulk emulsion explosives behave in different circumstances including depth and borehole diameter, giving the opportunity to re-evaluate blast design parameters such as its geometry, sequence pattern, charging profile and explosive composition.

Feb 2, 2020

By Sérgio Augusto Ferreira, Alan Gerson Diaz Butron, Carlos E. Arroyo, Marcus Neves, Jorhs Enrique Casimiro Huayhua, Dieggo Santos, Eventomar Junior

The presence of natural underground cavities is normally a characteristic of iron ore deposits, specifically in tropical deposits. Brazil and the United States are the only countries that have a legislation to protect these structures, but in Brazil this legislation is very specific for the existing cavities in the federal territory. These cavities are classified by their level of relevance as high, medium, and low. From this perspective, its preservation becomes mandatory, especially, for those of high relevance in order to protect the species (flora and fauna) that live in them. When these structures are within the production phases, it becomes a challenge to exploit these reserves with the use of commercial explosives, since these structures condition and may restrict the use and amount of explosive charge. This paper presents the methodology of controlled blasting associated with predictability via realistic simulation in production polygons, applied in a Brazilian iron ore mine where there is a presence of high relevance natural cavities with restrictions in relation to the limits of Peak Particle Velocity (PPV), which is product of detonation.

Feb 6, 2023

By S. Mansfield, A. Sharma

At a large open cut copper mine, in pit crushing and conveying is used to shorten haul routes and minimise stockpiling of ore. This strategy decreases capital expenditure by reducing the number of haul trucks and excavators required and reduces the need to rehandle ore from stockpiles with a secondary load and haul fleet, with an overall goal of lowering operating costs and carbon emissions. As the mine has developed and expanded, it was necessary to extend the conveying network and install a fourth, semi-mobile crusher to increase the output of the operation, while maintaining the operational efficiencies. This required the blasting of a new tipping bench and pocket for the installation of one of the largest and most powerful semi-mobile, crushing plants. Fed by 360 tonne (396 ton) ultra-heavy class haul trucks, the KB 63-130 Pro gyratory crusher is the highest capacity available in the market. This paper describes the holistic process that was applied to model, design and execute the blasts required to create the pocket for the semi-mobile crusher, the surrounding tipping bench, plus the conveyor corridor and access ramp used by the ultra-heavy class trucks.

Jan 1, 2024

By Steve Dillingham

A blast site incident has just occurred. Tensions are high, and, as the blaster, you’re in charge of the crisis at hand. Your mind is reeling, your thoughts frantic. The main areas of concern for you at the scene are to deal with immediate problems...aid the injured, take a head count, assess the damage, call emergency response, contact company headquarters, calm the neighbors, update your customer, and respond to the press on site. You feel as if all the bases have been covered...but, then again, have they? One of the biggest mistakes blasters and their companies can make is not including their Insurance carrier in the critical on-site accident procedures and emergency call list. Unfortunately, many companies believe that they are immune to the perils that can often, within a matter of minutes, create chaos that only happens to someone else.

Jan 1, 2002

The common approach of designing blasts on a trial and error basis is quickly coming to an end. When utilizing the full scale blast environment, trial and error can quickly become cost prohibitive and leaves much to be desired in terms of true blast diagnostics. In these situations testing is usually only continued until a perceived improvement is achieved and when the gross undesirables in blast results are removed. This does does not preclude, however, that further improvements of up to 100% or more can not be obtained.

Jan 1, 1991