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By Eric Roller, Elliott Giles

All flyrock incidents have the potential to result in injuries or fatalities that can result in loss of company reputation, license to operate with clients, and bear the exposure to high cost liability. From 2007 to 2009,one NA Quarry and Construction Business experienced a series of flyrock incidents. In the spring of 2009, this business declared that the frequency and severity of Flyrock Incidents had reached an unacceptable level. A Flyrock Elimination Program was launched.

Jan 1, 2012

By Regina Rocha, Miguel Humpire

One of the challenges within unitary mining operations is blasting, which has a significant downstream impact on the following processes, which is why mining companies ensure the results of the blasting process through joint work with explosives specialists’ companies.

Feb 6, 2023

By Tapan Goswami, Brent Geoff

Mining multiple steeply sloping coal seams introduces challenges in terms of safety and productivity. Work on steeply sloping surfaces for the processes of bench preparation, mark-out, drilling, loading and blast tie-up, coal cleaning and recovery is inherently hazardous. Furthermore, a large number of mining cycles is usually necessary, as small rounds are required and each layer is separately drilled, loaded, blasted and excavated. This exposes personnel and machines to additional risks and also incurs higher unit costs of mining as machine productivity is reduced. A case study is presented of a mine in New South Wales, Australia where three coal seams are separated by layers of inter-burden rock. Due to the unfavourable sloping nature of the coal seams the conventional practice was to drill and blast each layer separately.

Jan 1, 2010

By Jeff Gore, Jack Dermody, David Gribble, Brett Macaulay, Bart Sharpe, Paul Klaric, Paul Thornley, Ben DeVries

Optimal Fragmentation in Block Caving is difficult to achieve as it is generally defined by the rock mass itself and the way in which the cave is initiated. The lower portion of the cave has even less chance as the material has little time for self comminution. Blast Preconditioning of the Block Cave is designed to engineer the lower section of the rock mass to produce material of a suitable size to assist in the initial cave propagation and improve initial drawbell productivity. At Cadia East a plan was developed to drill 150-metre long, vertical up-holes from the undercut level and blast them fully confined to produce fractures in the rock mass. The blast itself was a simple undertaking. However, in the year preceding the first production blast, all aspects of the process were designed, tested and refined across multiple trials. As this type of challenging application had not previously been encountered in Australia there were many unique situations to address. Products and systems had to be developed and adapted to overcome these challenges. These included: Formulating and manufacturing an explosive that is robust and of a high VoD; designing and manufacturing easy to use electronic initiation systems; and, designing pumping systems to combat high head pressures to allow for successful and safe loading of the holes. Close collaboration with the customer ensured that the trials culminated in successfully blasting a hole containing almost 3.3t of explosive. These trials have since led to the blasting of four holes instantaneously, which contain almost 13t of explosive. This paper describes the various components of the system, the challenges and the final result.

Jan 1, 2013

By Braden Lusk

Vibrations as a result of blasting practices in mining engineering are a complex phenomenon controlled by many variables. Mine blast vibration modeling and prediction is becoming more important as a consequence of interactions by mining activity with an ever closer public. Many communities (all over the world) close to mining activity often complain about airblast and vibrations produced from blasting activity. It is important for the mining industry to have tools and understandable methodologies to model and predict blast vibration. These tools can then be used to predict and control vibration at neighboring structures.

Jan 1, 2013

By Clayton Thompson

Linear detonation wave generators (DWGs) shape a detonation wave so that every portion of the wavefront reaches the target “line” simultaneously. A projection-type linear DWG uses Gurney plate velocity predictions and Taylor deflection angle predictions to estimate the angle at which a thin projected flyer (typically metal) will impact a target. A mousetrap-style planar DWG consists of two projection-type linear DWGs working in succession to create a planar wave-front through shock initiation of each successive target explosive. The angle of deflection is critical to yielding a planar or linear wave profile. Gurney predictions, nominally accurate to within 10% of empirical results, may not yield ideal linear or planar detonation behavior when used with a grazing projection-type DWG, which typically requires accuracy within 2%. Simulations were conducted using AUTODYN hydro code to compare deflection angle prediction methods. Ranges of minimal error between Gurney and Taylor predictions and the results from the hydro code were determined, using PBX-9404-driven polyethylene flyers.

Jan 1, 2011

By Martin Schrier

This paper is an overview of a granite quarry cleanup near Kirkland Lake, Ontario, Canada. A combination of local geology and previous subpar blasting techniques led to the quarry needing significant rehabilitation before it could proceed with general operation. Advanced technologies were implemented into the blasting process, including laser profiling, bore-hole tracking, and geometric timing. The contract consisted of two floor shots and two 25,000 tonne (27,558 US ton) production shots.

Jan 1, 2018

By Dr. Anthony J. Konya

The modern era has seen a boom in virtual training platforms. This study details the effectiveness & applicability of online training in comparison to in-person training for the drill & blast industry.

Feb 1, 2020

By David Scutt, David Noon

Blast crews are exposed to a number of major hazards including explosives and chemicals, ground conditions, machinery, unique work environments and specific blasting hazards such as fly rock and misfires. Unfortunately, injuries caused by sudden and/or unexpected movement of ground are continuing to occur. Blast crews are not equipped with the knowledge or tools to understand whether a high wall that they are planning to work under is safe.

Jan 1, 2011

By John A. Huber

At an underground limestone mine in the Central United States; there were plans for the installation of a limestone processing plant. The special design and layout of the plant called for the installation of a tunnel from the underground mine to the surface above. The dimensions of the tunnel would be 10 feet high, 20 feet wide, and would be 500 feet long on a 17 degree incline. The tunnel would be used for the transportation of raw stone to the surface by a conveyor. A second conveyor would transport processed limestone into the mine for storage, that would be loaded out for shipment later.

Jan 1, 1995

By Alejandro Berrios, Matheus DaSilva, Erick Siqueira

Vazante mine is an underground polymetallic mine that produces zinc, lead, and silver, which belongs to Nexa Resources in Minas Gerais, Brazil. The mine, a sublevel stope underground mine, mainly applies two subvariants: VRM – Vertical Retreat Mining and Open Stope. In a specific place of the mine, the geology allowed the design of a production stope with larger dimensions than the standard stopes, commonly called Super Stope. At this place, the plan was to apply both sublevel variants simultaneously. This mining block comprises rings in two different levels, with access by two ore drives on each level; the dimensions would be approximately 50 meters high, 50 meters long, and 35 meters wide. Opening the Free Face to mine the whole Stope was a challenge due to operational issues, such as hazard risks from loading over void space, exposure to uncontained places, and the impossibility of implementing the optimal blast sequence. Wireless blasting initiators have gained popularity recently due to their convenience, safety, and efficiency. This initiation system was applied to preload all the rings required to open the Free Face, ensuring a safe and optimal blast sequence. Wireless initiation prevented hazard risks, enhanced the blast sequence to guarantee the required void space, and optimized the equipment's operational cycle. The blast crew carried out the activity without exposure to the risk of loading over void space. The wireless detonators also avoided after-blast activities, which were required to provide secure access to the blast crew, optimizing the operational cycle.

Jan 21, 2025

By Donelson A. Robertson

Proper coupling between the seismograph transducer and the surface is the most important aspect of seismograph monitoring but probably receives the least attention in many blasting situations. Without good coupling, particle velocity measurements may be higher than actual and frequencies may be lower. If the field data are inaccurate, sophisticated instrumentation and computer programs cannot correct the readings.

Jan 1, 1993

By Alexandra Yuyali

The objective of this research work is to increase the drilling ratio represented in tons per drilled meter (ton/m) to reduce mining costs. One of the key characteristics of this research is the use of the ITH (in-the-hole) drilling rig with a water-powered hammer, also known as Wassara™. The patented Wassara™ in-the-hole hammer is powered by high-pressure water instead of air. To reach the objective, a new design of the blast pattern was implemented considering the following: Burden from 1.7 m (5.6 ft) to 2.8 m (9.2 ft) Spacing from 1.7 m (5.6 ft) to 2.7 m (8.9 ft) Drill diameter from 89 mm (3.5”) to 102 mm (4”) Drilling length from 15 m (49 ft) to 30 m (98 ft) Borehole deviation < 2% The result of this new design is the optimization of the drilling ratio (ton/m); having as a baseline 5.2 ton/m with traditional equipment and obtaining 13.7 ton/m with the ITH drilling, which generates annual savings of $2.43M.

Jan 21, 2025

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 J. Esterle, J. Kruttschnitt

Fragmentation modelling in soft rocks presents a challenge due to their propensity to further fragment after blasting during normal handling. Coal and some iron ore deposits are examples of materials that undergo significant degradation during the extraction, hauling and dumping process of the mining operation. The Kuz-Ram model is an empirically derived predictor of size distribution from blasting hard rock. Little breakage occurs during excavation and subsequent sizing of hard rock, so the measured Run of Mine (ROM) size distribution is essentially the same as the post-blast (before excavation) size distribution. However, for soft rocks, each step of the excavation and hauling operation imparts energy to the rock particles so the measured. ROM size distribution will be significantly different from the postblast size distribution. In order to calculate the ROM fragmentation at any stage of the extraction (or sizing) operation, the JKMRC has developed a model that combines both blast fragmentation and degradation through subsequent handling.

Jan 1, 2001

By Leslie C. Taylor, Scott A. Yamada, William L. Fourney

Previous studies have shown that the pressure load on a target by a buried explosive charge is not smoothly distributed. The effort reported here was undertaken to explore the mechanisms believed to cause this uneven pressure distribution: jets from the surface originating in instabilities caused by the explosive shockwave interacting with surface irregularities. Small-scale tests using conical, hemispherical, and cylindrical indentations in the sand surface above a buried charge were conducted to identify trends in the velocity and form of the resulting jets. In these tests, the most important factor affecting the resulting jets was the distance between the bottom of the indentation and the top of the charge. Cylindrical indentations resulted in higher jet velocities than those from comparable hemispherical and conical indentations.

Jan 1, 2012

By Scott G. Giltner, Alex Schwenk

An iron operation sought to extend the life of the mine by conducting a major pit pushback in an area close to several public structures and the neighboring town. The result of the pushback would make millions of tonnes of ore available for mining allowing many additional years of taconite mining. This paper discusses the initial development blasts conducted for the pit pushback. For the development blasts, it was determined that no fly rock should leave the mine site and that the blast vibrations should be as low as possible, but specifically under 19 mm/s (0.75 in/s) at a nearby sewage treatment plant. One issue complicating the blast design was the variation in hole depth within any given blast. For the initial sinking shot, the hole depths varied from 6.4 m (21 ft) to 12.5 m (41 ft). In the subsequent blasts the hole depths within each blast could vary up to 5.8 m (19 ft). Various tools were employed to design the blasts to ensure there was no fly rock and that the blast vibrations were as low as possible. UAV surveys of the blast areas were conducted to provide a 3-D representation of the free faces and bench surface. The 3-D point cloud produced from this was used to measure the shape of the free faces. Once the shape of the free faces was quantified, it was possible to establish proper placement of the crest holes and develop a custom explosive load for each blast hole. In addition, signature hole analysis was performed for each blast to determine the optimum delay time that balanced the need for minimal vibration, prevent fly rock, and a well fragmented muck pile. Electronic detonators were applied to achieve the necessary control of the blast that balances these three concerns. The results of the seven blasts conducted to date provided the desired results. The peak vibration level at the sewage treatment plant for the seven blasts was 10 mm/s (0.40 in/s). The only fly rock occurred when there was a miscommunication in the blast design resulting in under burdened holes on the front row. To date, the mine has been able to safely expand the pit into an area that will add many years to the mine life. The muck piles have been well fragmented with reports from the shovel that they have all dug well.

Jan 21, 2025

By Robert Jacob Cefalo

In 2019, the Bingham Canyon Mine, owned by Rio Tinto Kennecott Utah Copper Company, mined through the active underground that dewaters the pit. The active underground required the limitation of vibrations to avoid catastrophic damage or damage that would require work to the shotcrete and additional roof support. The surface design of the current sector was mined next to and through portions of the active underground.

Feb 1, 2020

By N Gkikizas-Lampropoulis

Selection of delay times to optimize fragmentation has been a controversial topic among researchers and blasting practitioners. This paper interprets previous experimental information on the effect of delay on fragmentation with the aid of some new experimental observations of the time of detachment of the free face of the blast as well as results of numerical modelling. It was shown that detachment of the burden occurs at delays shorter than the one which produced optimum fragmentation in the experiments, suggesting some fragmentation improvement due to gas action. In addition, at the spacing to burden ratio of the experiments, the damage zone from an earlier detonating charge extends the distance to the neighboring charge, essentially affecting the burden of some of the holes of the blast, at detonation time. Computer modelling demonstrated that increased spacing results is less overlap of stress induced damage zones meaning that there is less influence of delay on stress wave induced fragmentation. It was also shown that simultaneous initiation results in less back break, while increased back break may result even with short delay times.

Jan 1, 2016

By Jorge Blázquez, Pablo Ravanal, Paulo Couceiro, Juan Navarro

Blasting performance is influenced by rock mass properties and blast design parameters. From them, the rock is the only variable that cannot be modified, but it can be measured, so that, blast design variables can be adapted to optimize the results. A new methodology to assess rock mass quality from drill-monitoring data from both autonomous and manual rotary drilling modes is described to guide blasting in open pit operations. For that, a thorough normalization process has been developed to minimize external influences induced in the data by the rig system for autonomous mode and by the operator intervention for manual mode. Principal component analysis has been used to combine MWD information. Two rock description indexes are derived directly from Measurement While Drilling (MWD) data collected. The first index is a Structural factor that classifies the rock mass condition in three classes (massive, fractured and heavily fractured). The second index is a Strength factor that classifies the rock according to the strength properties. Both indexes have been combined to obtain an overall drilling rock factor along the hole. This has been named by the authors as the X-Rock model.

Feb 6, 2023