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By O. Cermak, F. Degonld

Although 3D fragmentation analysis is a relatively new technology, it is rapidly gaining popularity among mid-sized mining operations and quarries. The results provided by this technology are adequate, but like other picture analytic methods, it mainly focuses on the surface of the muck-pile. These results are incomplete or incorrect as falling rocks and boulders from the stemming zone are constantly influencing the muck-pile surface. This obstacle can be overcome by collecting a large amount of data and analyzing it over time. However, this is not always an ideal solution, as companies prefer to receive results immediately after the blast to make resource allocation decisions, production planning, and plan for the next blast. Over the past year and a half, we have conducted a study on various muck-pile fragmentation analysis results from 3D modeling in Central Europe, comparing the results between the surface and inside of the muck-pile. By analyzing multiple shot results, we were able to determine the percentage difference between the top and inside fragment sizes and calculate the range of correction coefficients for different rock types. Applying these coefficients to a single muck-pile surface fragmentation analysis allows us to determine the actual fragment sizes inside the muck-pile. This enables us to make informed decisions regarding loading, hauling, material mixing, and proper crushing or milling. By overcoming the limitation of surface-based analysis, we can now accurately evaluate blast performance, which leads to better processes optimization and increase efficiency. As 3D fragmentation analysis becomes more widespread, we expect to see even more benefits for the mining and quarrying industry

Jan 1, 2024

By Ray Slavin, Remi Proulx

The Meikle Mine is a mature underground gold mine utilizing primary and secondary longhole open stoping method with delayed backfill. Combined production with the newly developed Rodeo Mine is 4700 tons per day (4265 tonnes per day) of ore. The vast majority of Meikle Mine production comes from secondary and remnant stope blocks. Remnant stopes are ore blocks that were left behind in the initial mining sequence due to various reasons. Mining of these remnant blocks has created many challenging blasting situations. The application of electronic initiation to blast remnant stopes has proven extremely beneficial. Electronic initiation has provided the blasting engineer with a high degree of flexibility with respect to timing to successfully extract these difficult stopes. Post blast assessment of the remnant stopes using the mine’s cavity monitoring system (CMS) demonstrates that the mine is maximizing ore recovery and minimizing waste dilution. The largest remnant stope blast to date required 54 holes and produced 6700 tons (6075 tonnes) of ore. Another area where the application of electronic detonators has proved successful is in the extraction of slots in which ground conditions are extremely poor. Taking the slot blasts in one shot with double-decked holes as opposed to two single-decked shots has eliminated the need to clean and or re-drill holes. The ability to open the slots in one blast has helped reduce the total mining cost. This concept has recently been expanded to blast complete stopes in one shot. This reduces the stope cycle time considerably and allows the mine to bring ore forward. Current plans for 2004 are to excavate 50% of mine wide stope production using electronic initiation technology.

Jan 1, 2004

By Alejandro Ferrada Vergara, María Jesús Barros Godoy

Reducing costs while maintaining productivity and achieving good results is a constant challenge in mining operations, especially in the drilling and blasting stage, since a bad blast can affect production plans, increase costs, affect safety and jeopardizing the pit stability. Examples of undesirable blasting effects are: flyrocks, boulders, loading equipment damages, lower production rates, etc. In some of the biggest open pit mines using conventional blasting patterns visited by the authors, the pattern does not adjust properly to the rock mass, in most cases blasting polygons are large and the rock mass condition is variable within the designed blasting pattern. On the other hand, conventional blasting patterns with stemming columns use 40-50% of the blast hole with inert material (the stemming). Moreover, blasting engineers spend efforts to improve fragmentation results by increasing explosive charge in spite of having the negative effect of ground vibrations, with little or no success. The classic approach is "the more explosive in, the better the fragmentation is", furthermore it is assumed this relation is direct and infinite, but it is definitely wrong. This work challenges the notion of a limitless direct relationship between explosive charge and fragmentation, this means this is partially true but just up to a certain limit. In other words, there is still room to improve energy distribution among the classical blasting techniques without increasing the explosive energy by using air decks. In the work to be presented air decks are built using conical shaped stemming plugs called Paraplug®. The results obtained suggests a wedge effect acts in the bottom of the stemming column that cushions the shock wave and the air deck to reduce the detonation pressure (this is due to the decoupling factor resulted from the air deck). The demonstration shows improvements in fragmentation results, reduced vibration records accompanied with lower dust column and costs savings in explosive charge.

Jan 21, 2025

By D. Lansburg

Electronic detonators are increasingly being used in today’s blasting in quarries, seismic, surface and underground mines. Electronic detonators offer several distinctive features over electric and non-el (shock tube) detonators including better timing accuracy resulting in excellent fragmentation and vibration control, field programmability and digital safety means. Because of the prerequisite electrical communications between the electronic detonators and the blasting machine, the layout or hook-up of these detonators can play an important role in obtaining the communication fidelity.

Jan 1, 2011

By Dale S. Preece, Ruilin Yang

"Air-decks are often employed for presplitting along the final highwall of a blast and are sometimes also included at the bottom or in the middle of explosive columns in the production portion of a blast. Shock wave physics is an important part of air-deck behavior since the bulk explosives in the column impart a shock into the air-deck where the air shock then passes through the air-deck at a rapidlyattenuating velocity. Through both high-fidelity modeling and shock physics theory it is shown that theresulting pressure in the air-deck is two orders of magnitude less than the detonation pressure of theexplosive."

Jan 1, 2017

By Tony Rorke, Sydney Thabethe

A large overburden blast was carried out at Douglas Colliery, Middelburg Mine Services, close to a national road in South Africa. The road is a busy route between Witbank and Bethal and damage to the road could not be risked. The section of road next to the blast was particularly prone to damage, because it had been mined out on its eastern flank, and the large blast was to take place on its western flank. There were thus three potential damage risks: 1. Fly rock damage to the road surface 2. Vibration damage to the road substrate 3. Damage caused by bulk displacement of the block supporting the road into the void on the mined out side. This paper presents the design and blasting methods used to control the blast and avoid these three risks. Electronic delay detonators were used in multi-decked holes. Signature data were used to determine the blast timing to make sure that delays were used that would provide destructive interference. The timing direction and sequence was decided using wave interference patterns to direct repeated shocks away from the road. The precise detonators and the odelling capability allowed effective control of the blast vibration result. Each hole was charged with two explosive decks separated by a deck of aggregate to limit the charge mass fired per delay and thus limit the reaction forces acting towards the unsupported road. The vibration and blast results are presented in the paper, together with the design that was applied. Details are provided on how the blast was charged and primed. The detonators that were used are described and the timing design is presented.Copyright © 2004 International Society of Explosives Engineers 2004G Volume 1 - Blasting Next to an Unsupported Road Using Electronic Detonators 1 of 13 It is concluded that damage risk to nearby structures can be effectively controlled using electronic delay detonators, provided the appropriate modelling is applied to obtain the most effective delay periods.

Jan 1, 2004

By D. Lee Petersen, Travis Davidsavor

The 2003-2004 expansion of a Duluth medical center required rock blasting adjacent to the existing structures, a Mn/DOT retaining wall and other urban structures. This case history describes the methods of a blast damage assessment, based on blast parameters, excavation locations, and critical vibration receptors (including surgical suites, a linear accelerator and a major retaining wall). The assessment concluded that blast vibrations could be controlled, by limiting charge weight, to eliminate impact at the critical receptors. Prior to construction, we conducted preconstruction surveys on structures susceptible to vibration damage. During construction, we reviewed submittals, observed test blasts, reviewed blasting logs and monitored blasting vibrations. Up to 13 seismographs were used simultaneously. Close coordination with medical center operations personnel was necessary to prevent impacts to critical medical procedures. Measured vibrations were clustered around the predicted values, and attenuated at the predicted rate. High-frequency blast induced ground vibrations induced low-frequency vibration of an adjacent MnDOT retaining wall. Medical center structures were observed to significantly attenuate the ground-borne vibrations. This paper was first published in the Proceedings of the 56th Annual Geotechnical Engineering Conference, 2008, at the University of Minnesota.

Jan 1, 2010

By Denard Brandt, Isidro Martinez, Greg Baker, Laura Slattery, Teddy French

The Dos Pobres Mine is a copper oxide heap-leach mine located near Safford, Arizona. Mine production is 180,000 tons (163,293 tonnes) per day with a stripping ratio of 2:1. During the startup phase of the mine, the required fragmentation size was easy to achieve as the ore was highly weathered and fractured near the surface. As the mine depth increased, the proper fragmentation size became harder to achieve due to less weathering and different rock types. Because copper recovery increases as crusher product size decreases, achieving the appropriate product size at the crusher is the operating priority.

Jan 1, 2010

By Jeffrey Meissner, Mike Waldron, Charles Dowding

Most studies of crack response have focused on opening and closing of a crack in the plane of the wall in which the crack occurs. Crack movement also occurs perpendicular or normal to the plane of the wall. This paper will examine and compare the in-plane and out-of-plane (normal) response of cracks in two different residences near limestone quarries. In two locations, sensors that measure in-plane and normal displacement were installed side-by-side on the same crack, allowing direct comparison of the two modes of response. In a third location, a perpendicular pair of displacement sensors was installed in a corner of a room to observe the bidirectional response of the structure at a corner. Both long-term and dynamic data were recorded with the same sensors; temperature, humidity, and air over pressures were also recorded to compare blast and weather effects. Measurements show that ratios of out of plane to in plane response to dynamic events can vary. However, the ratios of out of plane (normal) response to vibratory events to that of climatological change is still as small as the ratio for in plane crack responses.

Jan 1, 2010

By Paulo Couceiro, Manuel Lopez Cano

"The Panama Canal is one of the most important engineering projects of the modern era and plays astrategic role in the global economy and international maritime trade since its inauguration in 1914. Now, a little more than one century later, the final phase of its expansion program, the largest infrastructure works undertaken since its inauguration, has concluded. This expansion program has created a new lane of traffic along the Canal with the construction of a new set of locks – one on the Pacific side and another one on the Atlantic side -, increasing the Canal’s capacity and its impact on the world’s economy even more."

Jan 1, 2017

By John Hutchings

Drilling and blasting is a clearly delineated work process, which has well defined inputs and outputs. Drilling and blasting is also a process with a number of steps each of which has measurable outcomes. Drilling and blasting is ideally suited to the application of Total Quality Management principles. Most drilling and blasting information is generally poorly managed with disjointed and unrelated Information Technology systems managing parts drilling and blasting data. Data is often moved from on system to another, sometimes manually. In the field, drilling and blasting is still very much a paper based system and which has not generally benefited from some of the recent hardware and software technology advancements now “on the shelf”. Data collected on paper rarely is transcribed back into an electronic system for further analysis. It is often difficult to collate or review historic drilling and blasting data. This paper will present a definition of Total Quality Management and demonstrate how it can be applied to the drilling and blasting work process. Total Quality Management defines the mechanisms for the application of continuous improvement to drilling and blasting. Continuous improvement will provide opportunities to modify drilling and blasting work process outcomes and generate real cost benefits within the overall mining process. A complete drilling and blasting management system frame work, called DBS, is presented in this paper. DBS provides all the components necessary to implement a full drilling and blasting Total Quality Management solution. Also highlighted will be appropriate “off the shelf” technology that can be applied to replace current paper based systems and provide the means to connect with other mine data systems. Various examples will be discussed which will demonstrate potential benefits of applying a structured Total Quality Management approach to a drilling and blasting work process.

Jan 1, 2004

By A. S. Tawadrous

Fines are produced in any blasting application. Depending on the application, fines may or may not be a desirable product of the blast. In most quarry and construction applications, fines are considered an undesirable product since it does not constitute a sellable product and there are costs to the operation for disposal. On the other hand, in most open pits fines do not represent as much of a problem since the ore has to be crushed and ground after being blasted. Therefore, fines in such operations may reduce the energy consumed in the downstream operations.

Jan 1, 2012

By Tyler Acorn

In December of 2009 an estimated one million ton slope failure activated a 10 million ton mass impacting use of the main ramp system in the Newmont Gold Quarry pit. The failure left behind a 400 foot (122 meters), vertical to sub vertical scarp feature and shut down production in the lower benches of the pit.

Jan 1, 2011

By Shonn K. McNeill, Joshua Micah Hoffman

Security engineering is similar to other forms of engineering – the design is guided by the loads, materials, and desired function. For facility design, the load is the threat. Facilities that are designed with considerations for explosive hazards are designed with a shot, or series of shots, of a given size and distance from key locations. These facilities range from office buildings and industrial sites in developed nations to military and police stations in contingency areas. The challenge is the design shots are not often communicated to facility owners and managers. If the hazards change, whether it’s due to an increased capacity to cause damage by a threat or a decrease in capacity by a structure, not knowing the design shot means not knowing if security design needs to change. Blast modeling is an engineering tool that can be used to reverse engineer what a facility is suitable for, as well as be a tool for modifying security design for new conditions. This paper will examine military and civilian examples, including a case study of a military facility that did not know their as-built conditions and had to be rapidly closed; due to the determination their security engineering shortcomings could not be mitigated.

Jan 1, 2019

Currently there exist several explosive quantity-distance (Q-D) rules variously exercised by most countries to protect personnel and property against the effects of accidental explosions. These regulations apply to manufacture, transport and storage of explosive products. This paper reviews the technical basis behind these regulations, as they apply to commercial and military explosives. The characteristics of a blast wave and missiles issuing out of an explosion site and their role in determining the level of damage to a target are discussed. The need for further research on the effect of detonation of charges of non-standard geometry, and under confined conditions such as tunnels is discussed. The challenge in estimating the net quantity of explosives involved and calculation of its TNT-equivalency is also highlighted.

Jan 1, 2011

By Rachel E. Gooding, George C. Emmett, David R. Bradley

The United States (U.S.) Department of Homeland Security (DHS) Directorate of Science and Technology (S&T) is using a probabilistic risk assessment (PRA) approach to evaluate the risks from terrorist use of explosive materials against the Homeland. A similar approach is currently being used to evaluate the risk from terrorist use of chemical, biological, radiological and nuclear materials.

Jan 1, 2017

By C. K. McKenzie

Presents outline of flyrock model and a field procedure to validate predictions of maximum projection distance. Field results are presented from 13 field tests with two different hole diameters.

Feb 1, 2020

By Ethan Steward, Kyle Perry

To test the effects of impact on mine seals, a projectile generator and two seals have been constructed. The projectile generator is a 12-inch (30.5 cm) inner diameter steel pipe with a 4-inch (10 cm) wall, is 8.5 feet (2.6 m) in length, and sealed on one end. Projectiles are propelled by a charge of black powder with a wooden wad and are held in place by foam sabots in the bore. This system, combined with the large bore, allows firing of many different potential projectiles that may be found in an underground mine at a high velocity into the seals.

Feb 1, 2020

By John Norman

This paper will cover blasting techniques that are applicable to underground and other rescue that involves removing obstacles and breaking rock in close proximity to rescuers and subjects.

Feb 1, 2020

By C. Mick Lownds, Dale S. Preece, Ali Bhuiyan

FDM (Fracture Density Model) is a three-dimensional mechanistic model of blast induced rock fragmentation. FDM uses several computational mechanics algorithms to simulate the effect of blasting in different rock types. Earlier, FDM was successfully exercised to simulate 29 small scale shots from the United States Bureau of Mines (USBM), and 6 full-scale bench blasts at the Bararp dimensional stone quarry in Sweden. Excellent agreement was obtained for those shots, and the results were documented in earlier publications. One of the drawbacks of previous ver- sions of FDM was its inability to predict the fines, specifically in Bararp quarry simulations. Ac- curate predictions of fines can be very useful in reducing energy consumptions during down- stream comminution processes and improve the mine-mill operation efficiencies. In this paper, we propose a newer algorithm that can predict the fines as well as the coarse fragments in Bararp with reasonable accuracy. The model was also applied to an open-pit Copper mine with heavily jointed rocks, and it produced very good fragmentation predictions for the full range of fragment sizes. Comparisons with the sieved fragmentation data (for both Bararp stone quarry and the open- pit Copper mines) show great potential for this updated version of FDM in modeling the entire range of fragment size distributions in mining and quarrying applications.

Feb 6, 2023