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By Martti Hagfors, Mervi Hokkanen

The Finnish Defence Forces has destroyed obsolete and spoiled ammunition in open surface mass detonations at Hukkakero fell, in municipality of Kittilä, in Lapland since 1988. The de-struction method was learned from Sweden in 1987. The disposal camp is organized every au-tumn and it lasts four to six weeks. A gross weight of an average charge varies from 150 to 250 tons and the net weight of explosives from 15 to 25 tons. As a booster there have been used 2 to 3 tons of emulsion explosives. The explosives mainly consist of trinitrotoluene (TNT) containing smaller a mounts of amatol and hexotol. The Finnish Defence Forces Tech-nical Research Centre (PVTT) has studied the environmental effects of these mass detona-tions since they began in 1988.

Jan 1, 2011

By NA NA

Copyright © 2020 International Society of Explosives Engineers

Feb 1, 2020

By Guy Bridges

Site formation works requiring excavation of rock at the Queen Mary Hospital redevelopment site was restricted due to extremely low ground vibration limits. Non-Explosive excavation method called Electro Power Impactor (EPI), sometimes called Plasma Blasting, was utilised to help ensure the rock excavation rate could meet the required programme.

Feb 1, 2020

By Mick Lownds, Ruilin Yang

The potential advantages of electronic detonators with accurate timing have been increasingly recognized by the blasting community. However, in comparative blasts the results with pyrotechnic timing are sometimes comparable to those from electronic timing. Statistical variation in blast results is a plausible cause of these observations.

Jan 1, 2011

By Frederick B. Kuhnow

Harmonic energetic delamination a building is being considered for demolition at a formerly known atomic power lab. The building is within a containment structure under a negative pressure, so that no radioactive material is leaked out to the environment. A new approach was developed to make this work possible.

Feb 1, 2020

By O. Rielo, A. Pascoal, P. Katsabanis

The dynamic parameters of two different granites have been obtained using Hopkinson bar experiments. One series of experiments were conducted using a Hopkinson pressure bar apparatus with an explosive source to provide the compressional wave. This wave would travel along the granite bar and would be reflected at the free end. Strains were obtained along the bar to examine the process. Using relatively long bars of rock, approximately 300mm long and 18mm in diameter, the separation of the compressive and the reflected tensile pulses was possible. If the net tension exceeds the strength of the material, spalling is witnessed. By properly selecting attenuation materials and explosive sources, single spalls were created, making results easier to interpret. Numerical modelling enabled the calculation of the propagation of the stress wave along the bar and its reflection at the free end. Knowing the location of the spalls, critical stress levels for rock failure under tension were obtained. Dynamic tensile strengths were also obtained, at different strain rates, using a Split Hopkinson Bar Apparatus. The results provide a measure of the increase of the dynamic strength at high strain rates, relevant to blasting applications. They are useful for the calibration of blasting models and the characterization of rocks for blast modelling, but also provide answers to the basic question of what is the rock strength for blasting applications.

Jan 1, 2011

By Santiago Gómez, Pablo Segarra, José A. Sanchidrián

In this paper, differences between the industry-standard Holmberg-Persson (H-P) approach and a semi-analytical vibration prediction model called full-field solution (FFS) are analized. The analysis is conducted at two levels: vibrations and rock damage.

Feb 1, 2020

By S. Geerts, J Davidson

The purpose of the experiment was to determine detonation characteristics of various improvised explosives. The test consisted of detonating a pipe filled with an explosive compound inside of a plywood arena. The pipe will be located in the center of the arena to ensure even distribution on the witness panels. Details on pipe dimensions, weights of the pipe and explosive, and the density were recorded prior to testing for use in the model calculations. The same size pipes were used throughout to minimize the variables inherent in testing. The plywood witness panels will capture the fragments so that penetration data was obtained, primarily the surface area of impact and depth of penetration. Through the use of the penetration data in conjunction with a mathematical model the original fragment velocity was determined. The mathematical model was developed to measure lethality of fragments from explosives and was modified to determine the original fragment velocity instead. From this model other variables such as the Gurney velocity were calculated. This test was done with an explosive compound that was commonly found, and numerous improvised compounds. In order to guarantee accurate data all of the explosives used for testing were cap sensitive, to eliminate the need for a booster charge which would introduce many unknown variables. The one common explosive compound that was used was C-4 which has known data in order to show accuracy of the model and calculations. The other 5 compounds chosen will not have this data as they will primarily be improvised mixtures.

Jan 1, 2011

By Gungor Tuncer, Ali Kahriman, Abdulkadir Karadogan

In the bench blasting, the realisation of an economic, and safe blasting is only possible with a reliable blasting design on condition that considering all sequential activities such as drillingblasting, excavation-loading, haulage, crushing (especially primer crushing). Here what we mean with a good, and reliable design is that ensures an almost displaced, adequately swelled muckpile with desired fragmentation degree for the loaders effectivity, and succesive usage. Meanwhile it must also has no environmental problems such as ground vibration, air blast, and rock flyings, or at least these matters have to be minimised. Two main parameters which have generally being questioned to achieve a safe and economic design on any rock conditions, are specific charge, and burden. In the condition of determining these elements, the other blasting parameters could be calculated according to them, and the blasting design could be completed. Within the scope of this study, it was aimed to determine the optimal blasting conditions of gypsum which is major rock unit of overburden at Sivas Celestine open pit mine. First of all, the engineering (mass, and material) and digging difficulty classifications of gypsum were done according to the current classification systems by using the results of field and laboratory studies. Then the blasting system which was being used on all rock units, was considered, and the necessary data were obtained. After previewing the site properties, predesigns were done, and applied by adopting Langefors design model. The necessary adjustments were done before, during, and after the shots, and the applications were observed. In order to determine, and record the data from each shots properly, a practical form was developed, and all data were transfered to these forms which give information about the blasting results such as muckpile displacement, and height, average particle size, back break, and rock fly existence, number of boulders etc. The blasting parameters such as burden, hole diameter, hole inclination, the amount and position of primers, bench height, delay sequence, and blasting geometry were considered for the iteration of each shots. During the applications, ANFO, gelatine dynamite, and electric delay detonators were used as explosives.

Jan 1, 2004

"In this work a blasting seismograph was tested on a vibration shaker controlled by a single-point laser Doppler vibrometer (LDV). A total of 43 tests were made to measure the transfer properties(transmissibility and phase shift) of the basic elements of the full monitoring chain and investigate theperformance of the full system. The main elements of the seismograph are described by second ordertransfer functions with typical parameters calibrated through nonlinear fit of the measured responses. The resulting transfer function is used to compare the behavior of the tested seismograph with fourtheoretical seismographs representative of those used in blasting. Fifteen theoretical inputs are runthrough the transfer function of each seismograph to assess their steady-response. The error (expressed as gain) in the peak velocity has been assessed. It varies from -1.5 to 2.3 dB (equivalent to atransmissibility of 0.84 to 1.3, respectively) depending on the seismograph and frequencies of the input.The largest errors occurred for input signals with frequencies in the low (<32 Hz) or high ranges (>125Hz), where the mechanical, electronics and digital parts of the seismograph modify the signals. Seismographs with the nominal transfer function described by DIN 45669:1:2010 are ranked with the smallest errors. Monitoring devices with transmissibility around one in a narrow bandwidth, in line with ISEE suggested criteria for amplitude response, involve large phase shifts at low and high frequencies, resulting in a worst performance."

Jan 1, 2017

By Jianping Li, Ernesto Villaescusa, Kelly Fleetwood

During blasting, stress waves propagate through a rock mass, inducing stress and strain changes. This applied deformation affects intact rock, existing discontinuities, mine excavations, and engineered structures in the proximity of the blast. Traditionally in blasting, stress waves are quantified in terms of peak particle velocity (PPV) or peak particle acceleration (PPA), based on the method of measurement and the specified allowable tolerances. During analysis, the peak particle motion is coupled with an explosive source through various scaling laws to develop rock-specific attenuation relationships. Some studies have expanded this practice to the development of damage threshold values based on measured or predicted peak particle velocities. PPV-related thresholds are generally based on empirical models, where observation of overbreak, cracking, or fall-off are used to quantify damage. This method is often paired with the application of elastic plane wave equations to calculate the blast induced strain or the PPV threshold for tensile rock failure. Other factors that must be viewed critically in such models are the methods used to collect and analyse blast vibration data and the application of inappropriate vibration attenuation relationships.

Jan 1, 2009

By Nikolaos Petropoulos, Changping Yi, Daniel Johansson, Håkan Schunnesson

The effect of jointing on fragmentation by blasting was investigated experimentally and numerically. Firstly the experimental results were presented. Then the numerical modelling based on the experiments was performed. The same conclusions can be obtained based on both experiments and numerical modelling.

Feb 1, 2020

By P. Couceiro, J. Navarro

A new methodology to perform selective blast designs by adapting the explosive energy, hole by hole (or in the hole), to the rock properties as a combination of their strength properties through the X-Rock model has been developed based on drill-monitoring data from both autonomous and manual rotary drilling modes. For that, a thorough normalization process has been developed to minimize external influences in the data induced by the different rig system and the operator interventions during manual drilling operation. Principal component analysis has been used to combine drill monitoring information. Data from 48,385 blastholes, comprised in 102 production blasts at 7 different levels in one expansion of the mine have been used for the analysis. The methodology, called X-Energy, combines the X-Rock model outputs with actual blast design parameters (drill pattern, stemming and borehole length, explosive mass/density and others) and a constant variable obtained from a machine learning algorithm, to estimate size distribution and percentage of fines and coarse material, hole by hole, by combining and recalibrating the Kuznetsov (Cunningham, 1987) based equation. From it, a new shovel-independent diggability model has been developed as combination of the P80 size, the rock properties (from the X-Rock) and a constant variable obtained from a machine learning algorithm. The X-Energy application presented in this study have been implemented in Minera Escondida Limitada (MEL), to design and operate production blasts with the goal of varying the explosive density to the rock properties to obtain a more uniform size distribution and digging rates, hole by hole, based on a target size and rate, and improving slope care, preventing active faults to fail. The methodology has been applied and validated in 17 production blast (8,277 blasthole), unlocking an average of 12.8% reduction in explosives costs (explosive consumption), by combining a pattern expansion strategy and a better distribution of the explosive density within the blast. The results demonstrate how a better distribution of the explosive energy by varying its density in the hole according to the rock and blast geometry variables can reduce powder factor (explosive consumption) while improving or maintaining blasting and digging results.

Jan 1, 2024

By Gregory B. Poole

Data collected with 16K sampling at a variety of blasting sites (construction, quarry, trench, mine) and monitoring locations was analyzed to effectively show the 16 different 1K readings all based on the microsecond that the unit went into monitoring.

Feb 1, 2020

By Matthew Clay, Colin Chambers, Susan Hookham

Opencast (quarries) and underground mines around the world use blasting methods to mine valuable ore. Traditional blasting systems use technologies such as electric delay detonator systems (developed in the 1950s) and non-electric detonator systems (developed in the 1970s) to initiate a detonation train to blast rock more effectively, and so retrieve valuable product more efficiently. However, the lack of precise control over blast timings with these approaches can result in undesirable outcomes such as significant flyrock, excessive ground vibration, uneven grade of rock and misfires (in which sections of the blast can remain unfired). The development of Electronic Initiation Systems (EIS), first used in the 1990s, introduced a higher level of control over the blast. These systems greatly reduce the negative issues associated with blasting. However, this precision introduces complexity, and with this complexity comes difficulty in demonstrating the predictability, safety and reliability of such systems.

Jan 1, 2017

By Brad Bockey

Whether you are a driver, blaster, or are in charge of filing, you must recognize the importance associated with DOT-required recordkeeping. As various agencies become intertwined with rules governing the explosives industry, the records we produce must be as accurate as possible. The time is right for reviewing your paperwork process from start to finish.

Jan 1, 2011

By William Reisz

In our line of work,like many other professions, there may be times when circumstances or a series of events may arise, contributing toward unacceptable risk. When multiple parties are involved, there will almost inevitably be differences on how best to deal with these situations. Unless approached in an intelligent and these differences may often have the potential for costly and unexpected results.

Jan 1, 2014

By Bill Birch, Toby White, Ian Brown

costs/benefits of electronic detonators and measure their effects on primary crusher productivity. 9 blasts (3 shock tube blasts, 6 electronic blasts). Measured electricity consumption & primary crusher throughput. Change to Electronic Detonators resulted in a 7% reduction in primary electricity costs and a 15% increase in primary crusher productivity.

Feb 1, 2020

By Ian Bell, Saman Nouranian, Shahram Tafazoli, Bahram Sameti, Mahdi Ramezani

"Image-based rock fragmentation sensing in mining and quarry applications includes an important rock boundary delineation step, which is commonly referred to as rock segmentation. This paper presents a novel approach to solve this problem, using artificial intelligence. In the proposed technique, priorknowledge of previously analyzed images is encoded into mathematical/statistical models. A set of human labeled images are used as training inputs. These images are used to train neural networksthrough an optimization process. The networks can then be used in real time for rock delineation. "

Jan 1, 2017

By Frederick Kuhnow

In open pit blasting, energy is released and transmitted through the geology. Negative effects can impact operations and can affect mine production. This paper presents recommendations for blast design to prevent damage due to ground motion from blasting on adjacent concrete structures of underground operations. It includes a case study describing a problem regarding an open pit mine expansion and asks whether production blasting will damage concrete shaft structures due to blast stress waves and blast-induced ground motion.

Jan 1, 2014