Search Documents

By Paul Worsey, Matthew Coy

In the blasting industry, many different techniques are used to estimate and examine the effects of varying explosives and blast designs on the breakage of a rock mass. The overall objective is to find a cost-minimized blasting solution that also conforms to the legal and environmental concerns related to blasting. A major drawback to current blasting methods is the inability to account for "caprock," or a thick overlying layer found in sedimentary rocks that creates large amounts of oversize blasted material, especially on the top of a muck pile. This can lead to underestimating oversize in shots with massive top layers. A better fundamental understanding of blasting processes with caprock is required.

Jan 1, 2018

By Ankit Jha, Sudarshan Rajagopal, Purushotham Tukkaraja

Geologic structures are one of the crucial parameters in blast design. Structural geology and rock properties influence drilling patterns, blast layout, and initiation systems. A comprehensive understanding of structural characteristics is essential to achieve the desired blasting objectives. This paper aims to identify geologic features in a bench using images obtained from the drone. Images obtained from mine site are annotated for geological features such as faults and joints. Semantic segmentation of images is achieved using an encoder and decoder structure available in the machine-learning pipeline. The encoder consists of initial convolution and pooling layers to capture essential features of the geology and rock patterns from two-dimensional RGB images. Batch normalization is used to put all the features on the same scale. These images are then inputted as training data for the machine-learning algorithm. Machine learning model is trained on sub-section of interest to achieve reasonable accuracy. Initially, 1000 best annotations were used to train the model and additional samples were added later to achieve more accuracy and avoid iteration of machine learning model in wrong convergence. After the model achieves reasonable accuracy, it is used to recognize geological features on new data. Geological features identified on the new data can be used by the blasting crew in blast design and keeps the geological maps updated that can help the geotechnical team.

By J Silva Castro, W C. Wedding, B T. Lusk, J Calnan, E G. Morris

The emergence of electronic detonators for use in production mine blasting has enabled mining professionals to rethink the traditional blast design methodologies that pertain to timing. In many ways, electronic detonators can allow great advances in productivity, cost effectiveness, fragmentation, and safety. This paper reports on an independent study quantifying the accuracy of two electronic and two non-electric systems in which 674 detonators were tested. This research aimed to determine the accuracy of commercially available electronic detonators as compared to non-electric shocktube systems. Each system was tested over the viable ranges of delays available. Statistical models were then applied to quantify the scatter present in each system. Suggestions for the use of electronic detonators are made from the findings of this work. This work was made possible through funding from the United States Department of the Interior Office of Surface Mining Reclamation and Enforcement.

Jan 1, 2012

By H. S. Venkatesh R. Balachander, G. C. Naveen

During the construction of a 1020 MW underground hydroelectric project in Bhutan a huge rock fall took place in the Downstream Surge Chamber (DSC) during March 2016. The total quantity of rock in the fall area is estimated to be about 1,50,000m3 (2.6 billion cubic feet), out of which about 25,000m3 (0.44 billion cubic feet) of muck was removed. The removal of muck was stopped apprehending that the cavity formed due to the rock fall may get further aggravated leading to widening and destabilising the adjacent transformer hall cavern or it might day light as the top cover was about 190m (623 feet). As the fall has virtually blocked the 314m (1030 feet) long cavern and divided it into two different chambers (south and north), and that the muck cannot be disturbed, it was decided to erect concrete wall on either side of the fall up to the cavern roof and then later address the filling of the cavity with appropriate fill material. As the access to the DSC was there for the southern side it was decided to extend a cable tunnel which was terminated at a distance on the north side of the cavern by D&B so that once it gets punctured into the north wall of the DSC it can be used to access the fall from this front too. This is a unique situation where in every blast approaching the DSC, the parting between them is diminishing and hence the tunnel blast will be exerting axial load on the parting wall leading to dynamic transient loading conditions and buckling may take place on the northern wall of DSC. This paper describes the various drill blast combinations adopted for successful excavation of this tunnel.

Jan 1, 2019

By Lifent Li, Jhon Silva-Castro

Since millisecond-delay detonators were first introduced, at least two variables, among others, have been more closely considered when timing a mining blast: the accuracy and the precision of the initiation system. Currently, most mine blast design software has the capability to use the precision/accuracy of the firing system and display the overlap timing window between charges in any given time interval (8 ms, 3 ms, etc.). Despite these technological advances, there are still situations which result in the overlapping of charge timings. The consequences of overlapping charges involve flyrock events, fragmentation and diggability problems, and other inconvenient situations affecting the operation of the mine.

Jan 1, 2015

By Clara Godoy, Álvaro Dapía, Paulo Couceiro, Håkan Schunnesson, Juan Navarro

This paper applies geostatistical tools in Measure While Drilling (MWD)data to estimate the probability distribution of values in all the points of the studied domain in order to assess the continuity of rock classes between boreholes. The analyses carried out by Ghosh et al.(2018) and Navarro et al.(2019) have been used as starting point of this work to classify the geotechnical rock condition in four classes: solid rock, fractured rock, cave-in rock and cavity. From it, an application for the geotechnical rock condition of ore bodies have been developed, aiming at characterizing the rock before the charging the holes to minimize unexpected rock conditions and to address issues associated with charging and blasting operations. Such problems are closely related with non-optimal rock fragmentation after blasting. The procedure has been applied in the geotechnical block model results obtained from Navarro et al.(2019)’s work in the Luossavaara-Kiirunavaara AB’s (LKAB) Malmberget underground iron ore mine, Sweden. Navarro et al.(2019)’s model was developed based on102 fan-holes from five ore bodies and extrapolated to the full-scale in20 drifts with 5600 fan-holes from two orebodies. A multi-step transformation of the MWD parameters was carried out in order to minimize external influences other than the rock mass. The study shows the calculations of the variogram and kriging estimation in the 3D domain for six ring-blasts, from one of the ore bodies studied in Navarro et al. (2019)’s work to assess the continuity of the rock classes along the six ring-blasts in a 3D mapping model. For that, intermediate rings between the measured ones from the MWD have been estimated. The probability distribution of values in the entire domain of rings with measured samples has been plotted together with the rock classes identified by the blasthole paths. The results show high accuracy in the matching between the kriging and the values given by the MWD data, allowing to visualize smooth trends of different rock classes along the ring. The representation of the 3D mapping model for the six ring-blast shows clear fractured and cave-in zones developed along the drift that correspond to zones with geotechnical problems found, as from internal reports.

By Travis A. Davidson, Ralph E. Burnham, Cathy Aimone-Martin, J. Kelly Ratliff

Blasters face a long list of tasks to execute daily—from vehicle inspections to blast design and layout, hole loading and tie-in, securing the site, and finally, safely executing the blast. Good practices and, in most cases, regulations and requirements necessitate documenting their work, specifically their blast report. While some blasters use paper forms, others use electronic means to streamline the process. The authors have served as attorneys and expert witnesses in representing companies and individual blasters in numerous administrative and legal matters in which documentation of the blaster’s work was both critical and detrimental to the effectiveness of defending their work. This paper discusses in a case-study manner the authors' observations concerning good blast report format, specific observations around electronic and paper report completion, record-keeping, seismograph setup and recordkeeping, video and photo documentation, internal auditing, and other topics related to documenting the blast. The paper aims to serve as a discussion guide for blasters to improve their blast record-keeping process, develop better practices that effectively document their work, and allow them to defend their work should a claim arise concerning their operations.

Jan 21, 2025

By Robert Hopler

Blasting powder is a slow-acting, black, granular explosive made of sulphur, charcoal and either potassium nitrate (saltpetre) or sodium nitrate. The blasting powder containing potassium nitrate is known as “A” blasting powder; that containing sodium nitrate, as “B” blasting powder. “A” blasting powder is a little denser, a little stronger and a little less hygroscopic than “B” blasting powder.

Jan 1, 2014

By Wawa Jaka Sungkawa, Slamet Rachman Jaka, Tom Dermody

A project was undertaken to research and develop a method to confidently predict vibration. It was decided that the scaled distance formulas were not adequate to predict vibration when using non-electric detonators, as accurate wave propagation could not be achieved. The problem is how to manage of complex geology condition related with wave propagation in ground vibration control. Geological condition mapping with specific spatial range can and combine with Signature Hole Analysis be a solution to make wave propagation easier to accommodate in ground vibration control

Feb 1, 2020

By Ruilin Yan, Kameron Ray

This paper reports a simple approach to model the waveform change due to travel distances based on the field measurement. A linear interpolation is used to estimate the waveform at a distance from two vibration waveforms recorded at two different distances. The resulted waveforms are compared with actual recorded waveforms at the point in both time and frequency domains. It shows that the proposed method to estimate the waveform change yield reliable results. The advantages of the proposed method are that it does not require assumptions that a transfer function does and that it is based on purely the measured waveforms that are encoded with in-situ rock properties. The method could be more reliable for far field seismic waveforms and could be an approximation for near field waveform estimation.

Jan 1, 2014

By Carlos Pañura, Michael Geldres, Alejandro Rojas

The vibration waves are produced by the detonation of the explosive charges of each blasthole, analyzing the vibration waves produced by each blasthole, allow us to determine the optimal time between the detonation of each blasthole to reduce the vibrations of the production shot. Once the optimal time is found, it is possible also, to predict the vibration of the production shot (considering times and sequences) using predictive models. The waveform recorded includes information regarding the particle velocity and the dominant frequencies of the vibration.

Feb 1, 2020

By Josh Calnan, Paul M. Holmgren, Abigail N. Styer

Detonating cord is a staple of the explosives industry, used widely in the civil and defense industries. Detonating cord is a thin, flexible plastic tube filled with pentaerythritol tetranitrate (PETN). It has many applications in mining, construction and military disciplines. For civil applications, it is used to connect and initiate a series of blastholes in a desired pattern. In the defense sector, it can be used as a detonating agent, a priming agent or alone as an explosive charge. Research has been done to understand the initiation and detonation physics on the detonating cord. However, its sympathetic detonation characteristics needed to be further analyzed.

Feb 1, 2020

By M. Gebhardt, J. Johnson, S. Rosenthal

The use of presplitting applications in an underground mine setting is a method of reducing overbreak in the rib and back when blasting occurs. Presplitting performed at the Underground Mine Education Center (UMEC) on Montana Technological University’s campus in Butte, Montana showed a dramatic decrease in the amount of overbreak incurred in the blasting process. Application of the presplitting technique occurred after presplitting presentations at ISEE in San Antonio. Presplit testing consisted of drilling perimeter holes closer together than production holes and loading perimeter holes with a combination of specialized presplit explosive and packaged emulsion with electronic detonator initiation. The ideology was to shoot the perimeter row first, to create a fracture around the perimeter, so when the main production round is shot there is less shock exerted on the surrounding walls due to the pre-fractured perimeter rock. For the test performed, the back ended up with 83% of total holes resulting in half barrels representing a remarkable result. The right rib ended up with one half barrel visible before muck was removed while the left rib did not have any half barrels visible due to a clay seam being in very close vicinity to the perimeter row. The first test blast was a great start encouraging future work on presplitting applications in the UMEC. Additional testing will continue with different combinations of perimeter hole spacing, the addition of a buffer row along the ribs, and varying loading techniques to determine the most effective presplit method for the rock type of the UMEC. Detailed test results and loading configurations will be provided in the paper.

Jan 1, 2024

By G Mendoza, L Taddei, C Robertson

It is a well-known industry fact that many mine sites around the globe experience blast holes that have elevated temperatures due to reactive ground, geochemical reactions, geomorphic reactions, sub level open fires, etc. It has been reported in many previous industry publications (White, Saputra et al) that elevated blast hole temperatures are a norm at many mine sites and are dealt with on an ongoing basis while the drill and blast process continues under elevated states of alert. The choice of explosives products including the type of detonator, primer, accessory, and bulk product all must be taken into consideration when loading blast holes where there is a known potential for elevated temperature conditions. It should also be noted that these elevated temperatures inside blast holes can be consistent throughout the blast hole length or vary in position within the blast hole depending on the mine conditions mentioned in the opening statement above. The risks associated with the loading of primers and bulk explosives in holes where elevated temperatures are present include: the ejection of the bulk explosives product, deflagration of the explosives during initiation of the blast or premature and uncontrolled initiation of a blast hole(s). This paper describes a unique and novel approach to the active monitoring of the temperature within blast holes with the application of electronic detonators with integrated temperature measuring (ITM) capabilities, deployed and demonstrated at a mine site in Mexico during January 2023 to March 2023. The deployment of ITM capable electronic detonators allows a user to monitor and record the real time temperature at multiple locations (e.g., toe, middle and collar) at each electronic detonator’s position within the blast hole, with the ability to react instantaneously to elevations in temperature reported. The measurement of the temperature can be for a single ITM electronic detonator, or simultaneous for an array of ITM electronic detonators, allowing for the potential for the data to be represented by a time/temperature/hole depth three-dimensional heat map. Changes in temperature at different borehole positions can vary, however, often the collar position is expected to be the most reactive due the combination of bulk explosive product and oxygen exposure, which can be confirmed with the application of the ITM electronic detonators. A mine site’s reaction to a measured elevated temperature within a blast hole can vary depending on the temperature measured and the change in temperature from the last measurement made. The study was found to produce real-time in-hole temperature information which was previously unobtainable without the introduction of another device. New and adaptive elevated temperature hole policies can be created and adapted proactively as real time information is received, leading to a safer mining operation.

Jan 21, 2025

By Clarence Hall, Charles E. Monroe

Squibs, Fuse, and Detonators It has been made clear in the discussion of combustion and explosion and the description of various explosives that they can be caused to explode by various means. All of them can, under some circumstances, be made to explode by fire. Some of them can be caused to undergo a detonating explosion by setting off a detonator in contact with them. In blasting use is made of both these means for setting off explosives, the means used being determined by circumstances.

Jan 1, 2010

By John C. Adams, Darrel D. Porter

After conventional drill and shoot methods were determined to be unfeasible due the fractured nature of the ground, a "coyote" blast was designed to produce 250,000 tons of rock from Rhone-Poulenc's Maiden Rock silica pit located near Butte, MT. This paper will cover the design and excavation of the explosive drifts, the placement and priming of 190,000 pounds of explosives, and the backfilling of the drift to provide confinement of the charges.

Jan 1, 1993

By Stuart Brashear, Steven Bell, Donald Smith

This Limestone site required the removal of a bench containing high quality rock located in close proximity to sump and pit pump. The sump and associated electrical box were below the bench that needed to be blasted and located only 70 feet (21.33 meters) away. It was proposed to blast material needed without moving or disturbing the pump or electrical junction box. The area to be blasted was flown with a drone and stitched into a 3D orthographic model. Proprietary blast design software was used to create a blast design solution that would allow for a series of blasts that would provide required fragmentation and muckpile development and not disturb the sump or electrical box. A drill patten was created for each blast using the burden heat map and 3D face profiles created from the 3D orthographic model. Timing contour lines and muckpile displacement predictions were used to create timing sequences for proper face movement away from the sump and electrical box. The shot designs were laid out with a GPS system to insure hole location accuracy. All holes were remeasured for proper face burdens using the 3D model and Boretrak®® data collected after drilling operations were completed to insure hole locations were within face burden tolerances as derived by the burden heat map. After each drill log was reviewed, a charge loading scenario was created for each hole. The timing design created, for each shot and was reviewed and adjusted as needed with regard to desired muckpile displacement away from the sump and electrical box. Blasting results were satisfactory, with fragmentation and muckpile development consistent with the calculated throw from the blast model, with no rock hitting the pump or box and no rocks striking the sump water and disturbing the pump motor.

Jan 21, 2025

By Stewart A. Silling, C. Mick Lownds, Dale S. Preece, Ali Bhuiyan

GEM (Geologic Element Motion) is a Distinct Element Method (DEM) for modeling blast-induced heave. It was developed with a very fast computational algorithm that efficiently treats many different element shapes utilizing alternating arcs and lines to create GEM elements. The GEM computational technique has been previously documented so only a summary will be included in this paper. New features of GEM are the ability to define the size of the rounded corner radius as well the length of the sides for quadrilateral and hexahedral elements. Circles can be created from a quadrilateral element with zero length sides and four arcs. An additional new GEM feature is energy partitioning between brisance and heave. This physics-based partitioning is essential for accurate modeling of blast results over a wide range of rock and explosive types. It accurately defines the volumetric, pressure and energy state of the explosive gases in a blasthole following detonation. Rock mechanical properties and explosive characteristics are included in the calculations. Example simulations provide comparison of the GEM predicted heave for two different classes of explosive. A GEM simulation utilizing hexahedral elements is compared with previous modeling incorporating circular elements.

Feb 6, 2023

By Estefania Aramayo, Jhon Silva, Todor Petrov

Blasting is one of the most critical activities in a mining operation. Nowadays, many quarries have to follow a considerable quantity of environmental restrictions that drive the need to improve the conceptualization, design, procedures, and execution of the blast to comply with all regulations. Airblast is one of the variables required to control when blasting. Airblast is an unwanted side effect of blasting. Airblast is defined as an airborne shock wave resulting from the detonation of explosives. Traditional methodologies used for assessing the overpressure produced by the airblast are based on empirical approximations that require the collection of a series of produced airblasts before they can be used as a predicting tool. Once the data is available, regression analysis methodologies are used to find the constants of empirical laws that, in most cases, establish the relationship between the distance and the weight of explosives used in the shot (scaled distances laws). If using the traditional methodologies, the quality, and representativity of the scaled law established for a particular project are determined in terms of the correlation coefficient; in most cases, the models and their use as a predicting tool are questionable (very low correlation values).

Feb 6, 2023

By K. Dufresne

Blasting in geothermally high temperature ground and/or extremely reactive ground is an increasing common challenge for surface and underground mines. Many current PETN based non-electric and electronic detonators have manufacturer published in-hole temperature limits ranging from 55°C to 65°C (131°F to 150°F). When confronting blasthole temperatures above the manufacturer published limits, operations may request site-specific guidance and qualification for use. The advised safe loading window for in-hole PETN based detonators is often too short to be practicable for production blasting. To overcome limitations of PETN based initiation systems, surface mines with high temperature ground and/or reactive ground are known to load blastholes with a qualified high temperature bulk emulsion that are top primed with a cartridge of temperature qualified detonator sensitive emulsion plus an RDX detonating cord downline. As there is no in-hole delay detonator in this system, blasthole timing is accomplished with surface delays. Although this system is safe, top priming and surface delaying does influence floor quality and top size fragmentation, and safe loading windows times reduce blast block size and increase blasting frequency. A mining company with a site characterized by geothermally high temperature ground plus highly reactive ground employed a blasting system like the one described above. The site desires to improve blasting performance by moving to an in-hole delay initiation system that can withstand the site ground conditions. At the request of the mining house, DynaEnergetics (hereafter “the company”) developed an electronic initiation system for application in geothermally high temperature ground and/or extremely reactive ground conditions. The DynaEnergetics IGNEO high temperature electronic initiation system is rated for in-hole use in ground up to 150°C (302°F) for 48 hours. The detonator consists of a high strength detonator with an HMX base charge and thermally resistant downline. To make up a primer, the detonator is inserted into a booster charge assembly that is fitted with a small HMX shape charge. This high energy primer is designed to be compatible and reliable for firing bulk emulsions, including those with high percentages of urea inhibition to combat reactive ground. Up to 1000 detonators may be programmed in 1ms increments up to 1500ms. The system is controlled by a digital firing panel that can be used with either a wired or wireless trigger. The system enables high temperature and/or reactive ground sites to utilize in-hole delay initiation and realize the associated performance benefits

Jan 1, 2024