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By Stuart Brashear, Eddie Colburn

The Birmingham Coal and Coke – Knight Mine is a single seam coal mine in central Alabama. As pit development progressed in 2013, concerns over increasing vibration levels resulted in modifications to the blasting program that inhibited shot size and coal recovery. By January 2014, while still over 1,400 feet (427 m) from the regulatory seismograph, vibration levels climbed above 70% of the mine permit limit, even with triple decking of holes and reduced burden and spacing. At this time the decision was made to commit to the use of signature waveform analysis and precision programmable electronic detonators to minimize vibration and maximize the amount of coal that could be recovered before vibration levels reached permit limits.

Jan 1, 2015

By Wilfred G. Comeao

Close-in blasting occurs every time the use o f explosives for excavation or demolition requires the surpassing of the commonly accepted cosmetic damage criteriain order to arrive at reasonable and practical explosive weights per delay. One of the many effective blast design procedures consists in establishing a reasonable charge weight per delay with respect to scale, geometry, costs, requirements and constraints of the project. Once this reasonable charge weight per delay is determined, it’s environmental effects have to be estimated with respect to the surroundings.

Jan 1, 1991

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 not preclude, however, that further improvements of up to 100% or more can not be obtained.

Jan 1, 1994

By Thomas Barkley

Recent developments in hardware and software have made accurate measurement of Underground Face (Development) Drilling a reality. New and compact laser profiling equipment makes it possible to measure drilled material left on the face as well as the actual tracks of the holes drilled in the rounds. Utilization of these available technologies makes it possible to correctly define the drilling accuracy and the blasting pull. Through the use of actual face round measurements, I will show the level of definition and amount of information that can be collected.

Jan 1, 2003

By Francisco Sena Leite, Pedro Brito, Auã Kiahla, Raquel Carvalhinha, Tomi Kouvonen, Vinicius Miranda

Shockwaves that generate vibration in the surrounding environment of a blast, are one of the most important factors to control drill & blasting works near delicate buildings as well as in sensitive structures (wall control). On top of the damage to the buildings themselves, sensitive equipment such as computers, measurement apparatus and medical devices can be also compromised. The most commonly measured values from vibration are PPV (peak particle velocity), acceleration and displacement. Some devices and techniques have been developed in the last decades to measure the impacts of these vibratory phenomena. This information can be used to predict levels of vibration for future blasts and improve their quality of design using the attenuation law. From traditional studies to modern seismographs, a range of solutions are used for this propose. The main problem of applying this kind of technology is the high cost associated with each measurement device. In order to measure the ground vibration using new technologies while lowering the cost, a device has been developed using a microcontroller and electronic sensors commonly found on the market. This new equipment was tested side by side with traditional seismographs and the results were sent to a server for analysis. After several blasts, the necessary data was generated for the validation of the prototype. Through numerical mathematical processing (Taylor’s approach and numerical derivation) the original data supplied by the accelerometer’s sensors was transformed into velocity and, after the data mining, a statistics residue analysis was applied in order to evaluate if the data from the prototype and from the traditional seismographs were similar. The data from each system was used to estimate the attenuation law and the results are shown in this paper.

By Tamara Whitaker, James Gunderson, Ruilin Yang

This paper presents the results of a vibration control project conducted in soft overburden at a surface coal mine located in the western United States. The study uses near-field blast vibration monitoring, analysis and modeling techniques developed in house. Accelerometer-equipped seismographs were utilized for near-field vibration monitoring and analysis. Vibration control was achieved through field data regression as well as vibration modeling using the multiple seed near-field blast vibration model (Yang and Scovira, 2007). The regression was conducted between peak particle vibration parameters and the minimum scaled distance per delay. From the regression analysis, the curves of upper bounds for peak particle vibration parameters and charge weight were developed. The dominant frequencies of the blast vibration were also addressed in this project. The regression curves and near-field vibration model guided the blast design to control blast vibration for maximizing the recovery of coal and maintaining mine productivity.

Jan 1, 2008

By Benjamin Cebrian

Wall control blasting is an expensive and labor intensive operation. Obtaining a good design is a first step that is not enough to ensure desired results. Experience shows that designs are not always well implemented, not only in the contour blast itself, but also in surrounding production blasts that can affect the final pit wall. In this paper techniques and reference indicators are described in order to audit and evaluate if correct implementation of designs have been done.

Jan 1, 2013

By David G. Borg, John Bussey

The new AIRDEK (tm) technique for pre-splitting in surface coal mines produces highwall conditions that have greater safety with lower costs for explosives, labor, and drilling. Successful applications have been made in highwalls ranging from 20 to 100 feet or more and in blasthole diameters from 3-1/2 inches to 12 inches.

Jan 1, 1988

By Randall M. Wheeler

"Fourier analysis is a very powerful frequency analysis tool. However, it is frequently misunderstood and sometimes used inappropriately. Part of this workshop will involve the basics of Fourier series, the Fourier integral and finally the Fourier transform. Included will be a brief discussion of analysiswindows, including the box and Hamring windows."

Jan 1, 1998

By Barend Botha, Trevor Davids

The presence of an extensive soft siltstone layer in the middle of the inter-burden sequence of rocks at Syferfontein Colliery in the Republic of South Africa prompted tests to determine the effect of different mid-column decks of inert material in the siltstone layer. The objective was to achieve significant cost savings in explosives use whilst not degrading dragline productivity. An important factor that had to be considered was that the initiation systems available in South Africa are not accurate enough to ensure simultaneous initiation of explosives decks in a blasthole. A number of inert materials were tested including ash, drill cuttings, river sand and crushed stone. It was found that the ash, drill cuttings and river sand did not effectively attenuate the shock wave and that the risks of sympathetic detonation or partial disruption of one or the other explosives deck in a blasthole was high. This became much worse when the inert material was saturated with water. Crushed rock was the most effective in attenuating the shock wave, but this material was very expensive to use because it had to be imported onto the mine.

Jan 1, 2000

By Erkan Bayrak, Serkan Erkara, Ozkan Duzgun, Ekin Gungor

This paper presents part of the outcomes of the drill and blast optimization project carried out at Kisladag Gold Mine in Turkey. Kisladag Gold Mine is the largest gold mine in Turkey with a low-grade, bulk-tonnage, open pit operation that uses heap leaching for gold recovery. After blasting, the ore is fed to a three-stage crushing circuit which prepares crushed ore approximately -10 mm (0.39 in) for heap leaching. Crusher downtime analysis showed that blocky material and insufficient feed are causing significant downtimes with the primary crusher. This was supported by the fragmentation data collected to date. It was decided to initiate a fragmentation project to understand the variation in the run-of-mine (ROM) size with a view to provide a consistent feed to the crushing circuit. The study includes the analyses of the ore strength and structure, image analysis of the fragmentation pictures acquired from blasts, blast auditing and quality assurance and quality control (QA/QC) analyses. During this project, over 200 fragmentation pictures were acquired from 47 blasts to optimize ore and waste blasts. Ore strength varies between 30 and 120 MPa and rock quality designation (RQD) ranges between 30 and 100. A site-specific fragmentation model was used to calibrate the fragmentation for blast domains formed. In addition, alternative cases were simulated to achieve blasts designs with consistent ROM fragmentation size distribution. Alternative blast designs that include stemming length and powder factor changes were suggested. Long stemming length, drill cuttings use, free faced blasts, small shot sizes and poor stemming length control were some of the key issues causing coarse fragmentation.

Jan 1, 2015

By Italo Onederra, Jason Furtney, Ewan Sellers

The detonation reactions occurring during rock blasting result in high pressure gas phase products from the condensed explosives typically used in mining applications. After detonation and the initial fracturing, the work done by the expansion of this gas contributes to burden movement and further rock fracturing. Before all of the energy in the reaction product can do useful work on the rock, some of this energy is lost to crushing and possibly to gas venting to the atmosphere. Borehole gas pressure decreases by three principle mechanisms: (i) expansion of the borehole cavity, (ii) flow into the fracture network, and (iii) flow through the stemming. To simplify the problem and to get a better understanding of the interaction of these mechanisms, a simple model for each of these mechanisms is developed. A comparison is made of the time-scales and the influence on burden movement for each. A comparison of gas flow behavior is made between typical ANFO and emulsion products.

Jan 1, 2012

By Alastair Torrance, Mitchell Nipperess, Andrew Olsson, Italo Onederra, Gary Cavanough

Components of bulk explosive products include ammonium nitrate, water, fuel, stabilizers, and calcium nitrate. The physical attributes include prill/emulsion ratio, density, and viscosity and in the case of prilled ammonium nitrate, hardness, size distribution and fuel oil absorption. These components and attributes in conjunction with ground conditions determine all aspects of explosive performance including the risk of fume. This paper presents a fume risk assessment matrix of explosives components and physical attributes as a function of a simple description of ground conditions. Instrumentation to provide a measure of the quality of the explosive product are also described and these include both “on bench” physical measurements and laboratory analysis. “On bench” methods include “in hole “density, velocity of detonation (VOD), detonation pressure and detonation temperature. Part of the quality control process involves a mobile laboratory unit which at this stage can provide measurements of water content, ammonium nitrate content, calcium nitrate content, fuel content, prill characteristics and prill/emulsion ratio. This unit can be taken to sites to enable the testing of bulk and sensitized products at site rather than after transportation.

Jan 1, 2015

By Ewan Selers, Gary Cavanough

Drilling automation technology is well advanced and automated drill rigs are in use at a number of operating mines. This is not the case for the other drill and blast processes due to significant technical challenges to overcome. These challenges, with regard to the current “on bench” practices, include placing the initiators, loading the explosive and connecting up the initiation system. Although difficult, these challenges will be solved with engineering advances.

Jan 1, 2016

By R Castedo, L. M. Lopez, J. A. Sanchidrian

In 2014 the authors presented results from 13 tests made with two blasting seismographs on a vibration exciter. They measured coupling transmissibility as function of frequency (i.e. ratio of the velocity of the sensor mount to the velocity of the ground motion) from 16 to 200 Hz at one or two vibrations levels (5 mm/s or 0.2 in/s, and 20 mm/s or 0.79 in/s) with mounts freely placed, sandbagged, and anchored to a granite slab firmly attached to the plate of a vibration exciter. As the memory capacity of one of the seismographs prevented to cover low frequencies, e.g. 4-16 Hz, a new measuring campaign has been recently made to extend the study down to 2 Hz. In this campaign, two more techniques, in which the sensor mounts were fixed with thermal adhesive or a combination of duct tape and gypsum plaster, have been also investigated from 2 to 200 Hz at 5 and 20 mm/s. Free and sandbagged mounts lead to a weak coupling of the mounts to rock, so that transmissibility depends on the characteristics of the imposed rock motion (peak velocity and frequency). Measurements are accurate only at low frequencies (below 17 Hz for free mounts and 10 Hz for sandbagged) in the tested conditions (velocities up to 20 mm/s). Above these frequencies, ground motion in the measurement can be modified by a factor of 0.16 to 1.22. Anchored, glued and plastered mounts achieve a stiff rock-to-ground coupling, ensuring consistent measurements for the frequencies commonly found in blasting independently of the vibration level and the mount characteristics

Jan 1, 2015

By Benjamin Cebrian

Traditional dilution control systems range from computer modeling, use of physical markers on the field as polypipes to a technology that marks some control points where displacement is measured. The latter includes walking over a muckpile which is prohibited by some mining companies as a safety measure. The new technology presented in this paper is a patented system that is installed on board excavators (backhoe or front shovel types). Several control points are set along ore/waste contacts and their position is uploaded on the corresponding shovel. The operator proceeds on mucking until he is alerted when reaching any of the several control points previously located in the blast patterns and that have moved with the muckpile. A case study is presented at a high grade copper mine, were unique 3D shapes are showing as a result of using an on-board excavator dilution control system. Both ore-loss or dilution cost of opportunities are analyzed.

By P D. Kasbanis, Lyall Workman

"The energy output of an explosive is typically calculated using an equation of state and computerapplications. Results are reported as weight and bulk strength, either in absolute terms or relative toANFO. The effect of the equation of state selected and the assumptions regarding the energy calculation are considered and interpreted for the purpose of blast design. It appears that variations in the heat of detonation which result from the selection of the equation of state and parameters associated with it are not sufficient to significantly affect blast patterns, explosive consumption and costs. However variations stemming from the use of “available energy” associated with a cut-off pressure are significant, suggesting in many cases large pattern expansions. The validity of the various approaches is discussed and blast design results based on the energy calculated by the different approaches are presented and evaluated."

Jan 1, 1996

By Brandon Fryman, Josh Hoffman, Rhys Baker

A post-detonation debris collection project was led in conjunction with a large ammonium nitrate(AN) railcar detonation conducted by the Department of Homeland Security-Transportation Security Administration, Department of Defense-Combating Terrorism Technical Support Office, Sandia National Laboratories, and the U.S. Army Dugway Proving Grounds. This important work will aid in underpinning algorithms used in a Quantitative Risk Assessment (QRA) tool. The test also provided valuable data about the effects and consequences following an AN detonation. The test took place at the Utah Dugway Proving Grounds on April 27, 2018 and the debris collection was conducted the following two weeks with an average of 20 persons per day and an approximate total of 1,400 manhours. A paper was presented at the 2019 ISEE Conference on the collection efforts, challenges, and lessons learned. A complete data analysis effort was completed on the test data in 2019 that resulted in updates to the QRA Railcar Potential Explosion Site (PES)model and AN engine. The analysis included an assessment of the debris data resulting from the Derailed test. This paper is meant to serve as a summary of the analysis effort and findings and as an update to the previously presented lessons learned from the debris collection and analysis effort.

By Daniel Hauer

In considering the cost of rock excavation, but little attention has been given to the economical handling and breaking up of boulders. Very few records seem to have been kept as to the cost of such work, and although it is difficult for this reason, to set a fair price for breaking up and handling boulders of various sizes, yet the cost of this detail work enters very materially into the cost of solid rock excavation. The subject is worthy of close and prolonged study.

Jan 1, 2006

By D. J. Goodings, R. J. Bonenberger, H. U. Leiste, W. L. Foumey

This paper describes a series of two-dimensional tests conducted and filmed with a high-speed (500 frames per second) video camera. The purpose of these tests was to provide a better understanding of the processes involved in creating craters and channels in water covered soils with explosives.

Jan 1, 2000