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By Francis Otuonye

Rock fragmentation by blasting still remains the most common and cost-effective method of excavating hard rock in mining and tunneling operations. During blasting, the dynamic stresses induced by the detonation of the explosive, in addition to fragmenting the rock in the vicinity of the blast, may fracture the rock at considerable distances from the point of detonation of the explosive. The fractures can result in reduced mine safety, increased costs to support the opening, low productivity and perhaps high ore dilution. Besides the dynamic stresses produced in the rock, air blast overpressure pulses are generated and propagate through the network of underground mine openings. The waves, unable to spread out spherically or hemispherically like blast waves from surface blasting, are forced to propagate by reflection from the roof, ribs and floor down the drift. Blast wave focusing can occur and produce intense shock waves that could damage ventilation barriers such as cement block stoppings.

Jan 1, 1992

By Claude R. Ayoub, Charles A. Kliche, David G. McDowall

Homestake Mining Company's Open Cut Mine is located in Lead, South Dakota, in the northern Black Hills. The mine is within 300 feet of occupied residences on the south end, and within 1200 feet on the north end. Mining began at the north end of the open pit in October, 1983, and blasting related complaints began almost immediately. Noise and ground movement comprised the majority of the structural damage claims. As a result of these complaints, Homestake purchased a recording seismograph and began monitoring nearly every blast. In addition, the company hired a consultant to review Homestake's blasting and monitoring practices. He was also asked to do a single, one-time study of the cracks in six homes. This initial work led to Homestake monitoring all blasts with three seismographs and having South Dakota School of Mines and Technology do a year-long study of crack development and propagation in five homes in Lead.

Jan 1, 1989

By Clara Godoy, Paulo Couceiro, Juan Navarro

The continuous automatization and digitalization of the different stages involved in any underground construction bring new possibilities to optimize the operation. One of the most important requirements for the development of these projects consist of a proper rock mass characterization for optimizing the stages of the drilling, blasting and support cycle. In the last few years the road to digitalization has gone through data science and big data, showing the importance of data gathered to describe the geological and geotechnical environment that surrounds the operations. Since rock characteristics have an important influence in the drilling response, the technological advances in the sensorization of drilling machinery such as the Measurement While Drilling system (MWD) allow to gather the necessary amount of information to be applied in data science processes to evaluate changes in the rock mass with higher resolution than conventional methods. In this paper, Machine Learning techniques have been used to combine data monitored from the drill rigwith scanner profiles of the excavated sections to develop an automatic geotechnical rock mass characterization model able to estimate potential zones of over- or under-break of the remaining rock mass in underground blasting. By comparison of scanner profiles of the excavated sections with the blasthole positions, an Excavated Mean Distance (EMD) between the contour blastholes and the excavated profile has been obtained, which may be considered as damage measure. Considering blasting factors as constant, the model combines the rotary, percussive, hydraulic flushing and the rate of advance of the drilling, and the confinement of the rock mass by depth, to detect zones with different rock properties. This provide an early information of the rock mass condition around the blastholes and the prediction of expected overbreak generated after blasting, being possible to design more efficient bastings, in which each borehole is filled with the right and necessary explosive charge. The analysis comprises data from 57 blasts (around 1700 contour blastholes) and more than 4000 excavated sections.

By Clara Godoy, J. A. Sanchidrian

In this paper, Machine Learning techniques have been used to combine data monitored from the drill rig with scanner profiles of the excavated sections to develop an automatic geotechnical rock mass characterization model able to estimate potential zones of over- or under-break of the remaining rock mass in underground blasting. By comparison of scanner profiles of the excavated sections with the blasthole positions, an Excavated Mean Distance (EMD) between the contour blastholes and the excavated profile has been obtained, which may be considered as damage measure.

Feb 1, 2020

By Roger G. Sprague

With the passing of time, changing marketplaces and years of hard service, coupled with new machines, increased productivity, rapidly improving technology, equipment which used to be the latest in modern mining have now slipped into obsolence. Mining companies need reliable, productive equipment in order to compete in today's market. In Western coal mining, as coal seams become deeper, older equipment must be replaced with that which can do the job more efficiently.

Jan 1, 1998

By Mark S. Stagg, David E. Siskind

The Bureau of Mines arranged to have a wood-frame test house built in the pat of an advancing surface coal nine so it could investigate the effects of repeated blasting on a residential house. Structural fatigue and damage were assessed over a 2-yr period. The house was subjected to vibrations from 587 production blasts with particle velocities that varied from 0.10 to 6.94 in/s. Later, the entire house was mechanically shaken to produce fatigue cracking. Failure strain characteristics of construction materials were evaluated as a basis for comparing strains induced by blasting and shaker loading to those induced by weather and household activities. Cosmetic or hairline cracks 0.01 to 0.10 mm wide occurred during construction of the house and also during periods when no blasts were detonated. The formation of cosmetic cracks increased from 0.3 to 1.0 cracks per week when ground motions exceeded 1.0 in/s. Human activity and changes in temperature and humidity caused strains in walls that were equivalent to those produced by ground motions up to 1.2 in/s. When the entire structure was mechanically shaken, the first wallboard tape joint crack appeared after 56,000 cycles, the equivalent of 28 yr of shaking by blast-generated ground motions of 0.5 in/s twice a day.

Jan 1, 1985

By Steven D. Knudsen, Dale S. Preece

The spherical element computer code DMC (Distinct Motion Code) used to model rock motion resulting from blasting has been enhanced to allow routine computer simulations of bench blasting. The enhancements required for bench blast simulation include: 1) modifying the gas flow portion of DMC, 2) adding a new explosive gas equation of state capability, 3) modifying the porosity calculation, and 4) accounting for blastwell spacing parallel to the face.

Jan 1, 1992

By Kenneth Eltschlager

The Surface Mining Control and Reclamation Act of 1977 requires that blasting be conducted so as to prevent injury to people and damage to public or private property. The three adverse effects are flyrock, ground vibrations and airblast. Blasting close to people frequently results in complaints of annoyance or damage. Federal and State personnel are responsible for evaluating the validity of the complaint. The elements to be evaluated include: reviewing blast logs, inspecting the mine, inspecting the house, measuring ground, air and structure vibrations, and predicting vibration levels. Computer spreadsheets, with their graphical capabilities, will be used to show how data can be cross tabulated to verify data accuracy. Complete statistical analyses of vibrations require more powerful software to make vibration predictions. Once all available data are gathered and verified, a decision on the complaint can be made.

Jan 1, 2001

By Enver Alan

This Research & Development (R&D) study was conducted in the field of applied blasting engineering in Ethiopia, within the AKH Railway Project, which was built in Girena, within the boundaries of the province of Mersa, in the Basalt Quarry at km 346, Ashangi Formation, occured in Eocene geological time in the aphanitic trachibasalt.

Feb 1, 2020

By Seung-Kyu Baek, Chang-Ha Ryu, Yang-Kyun Kim

Safety concern is one of the most important parameters in the design of building demolition by explosive blasting. Accidents were sometimes reported due to the flying chips of fragmented materials in building demolition work in urban area. Laboratory experiments were performed to investigate the failure behavior of reinforced concrete pillars under blast loading and to develop an effective protection technique. Sixteen reinforced concrete pillars were constructed with two sizes: 450×450×1800 mm and 600×300×1800 mm. The failure behavior and the flying chip velocities were observed by means of a high-speed camera. Protection scheme was designed and the effects of several protection materials were investigated. Two kinds of non-woven fabrics and wire net were tested as protection materials. The results showed that reinforcing bar was one of the important factors to determine specific charges, and that mesh size of wire net and tied-up method affected the protection of flying chips. Control of gas effects is also a key to the control of flying chips. It was recommended to use both wire net and nonwoven fabrics as primary and secondary protection materials. Such protection scheme was successfully applied to the explosive demolition of 16 and 17-story apartment buildings.

Jan 1, 2002

By Mohammed Alkazimi, Katie Grantham

The purpose of this paper is to quantify the risk to both the environment and surrounding infrastructure from a pipe sealing implosion. Both accuracy and the precision in determining how a submerged infrastructure damaged by underwater explosions performs provide better decision-making capabilities for managers facing impending oil spills. This determination is vital, especially for both emergency and crisis management teams, as categorized consequences based on both the nature of the structural layout and the surrounding marine environment assist in identifying whether or not the utilization of this technique is applicable. Thus, the decision maker’s aim, in a crisis, is to minimize any associated risk that might result in aggravating the situation by endangering both the infrastructure and marine life. Therefore, the resulting risk matrices will enable technical personnel who are not experts in explosive technologies to be armed with the information necessary to determine if this mitigation technique is applicable to their situation.

Jan 1, 2013

By Randy Martin, Jessie Bonner, Peter Boyd, Mark Leidig, Timothy Rath

We conducted the Vermont Damage Experiment in central Vermont during July 2008. Five single-hole explosions with yields ranging from 60.8 kg (134 lbs) to 122.5 kg (270 lbs) were detonated in homogeneous, low fracture density granite. The goal of the experiment was to quantify the different levels of rock damage around the source and then relate the seismic wave generation to the degree and distribution of damage and fragmentation. In addition, explosives with different velocities of detonation (VOD), including black powder (0.53 km/sec; 1737 ft/sec), heavy ANFO (4.8 km/sec; 15734 ft/sec), and COMP B (8.1 km/sec; 26574 ft/sec) were detonated to relate the VOD to seismic wave generation and extent of damage zones in the source region. Over 120 seismic stations were deployed to record the explosions at distances between 5 m and 30 km (15 ft to 19 miles).

Jan 1, 2010

By Ulrich Leiste, David M. Fox

This paper presents the results from small scale testing aimed at measuring the loads on a rigid target due to the detonation of a buried mine. The aim of this research is to find how the impulse delivered to the target varies as the air filled void volume fraction within the soil changes.

Jan 1, 2013

By David La Rosa, Matthew Craft, Lee Julian

Rules of thumb are ubiquitous in blasting. Typically presented as ratios, they assist with the initial assumptions of blast design and provide guidance for best practice. Examples include the blast hole diameter as a function of bench height, and stemming length as a function of hole diameter. The most common rules of thumb were developed in mid-20th century and it is important for a blaster to know if the rules of thumb are still reliable.

Feb 6, 2023

By Valeri Mitkov

Studena Quarry is one of the main suppliers of inert materials for concretes production in Sofia. It is characterized by massif heterogeneity in density and fissuration. Failure to take into consideration this fact during the planning of the blasting works recently had unsatisfying results in their carrying out – obtaining of materials with too small dimensions or high percentage of outsize material. Series of test blasting were carried out to find the relations for calculation of the main parameters of the drilling and blasting works. The blasting network was enlarged to 6 x 6 m, the diameter of the shot-boreholes was changed from 110 to 152 mm, the stem of the boreholes was significantly reduced and the relative consumption of blasting agents as a whole was reduced to 0,37 ?g/m3.

Jan 1, 2010

By Ron J. Elliott, David G. Otto

This project involved deep blast densification of recent volcanic avalanche debris deposits consisting of a 43 meter thickness of loose clean to slightly silty sand, gravel, cobbles and boulders deposited as a result of the 1980 eruption of Mt. St. Helens, Washington, U.S.A. This project was carried out to enhance the resistance to liquefaction or dynamic settlement of soil deposits under the bridge abutments for construction of the 59.4 meter long South Coldwater Creek Bridge. As this bridge is located close to the Mt. St. Helens fault, it will in all likelihood be subject to earthquakes in the order of 6.5 with expected accelerations of 0.55g. Without soil densification, the bridge would suffer severe structural damage in the event of a significant earthquake.

Jan 1, 1994

By Luan Monteiro, Francisco Biulchi

The AngloGold Ashanti - Cuiaba mine sought innovative approaches to minimize lateral development and stope extraction time while maintaining optimal gold recovery and minimizing dilution. The stope 8GAL EXT 30 was selected as a case study. Traditionally, conventional blasting methods in such a scenario would necessitate either a single mass blast or slot development at each end of the stope. These methods typically compromise recovery and dilution or increase development time and risk. Additionally, conventional wired detonators require workers to re-enter the stope between blasts to load blastholes and connect detonators. The wireless initiation system offers a solution by initiating blastholes using magnetic induction signals that can penetrate rock, air, and water. This technology allows a pre-charged stope to be mined without requiring workers to re-enter the area between blasts to charge and connect blastholes. Engineers from Orica and AngloGold Ashanti designed a new extraction sequence utilizing the wireless initiation system. The process began with the opening of one end of the stope using a conventional slot and wired electronic detonators. Subsequently, pre-loaded rings were fired in three blasts to extract the opposite end and the intersection. The 8GAL EXT 30 stope was successfully mined using this technology enabled method. Each blast was meticulously monitored, and the stope void was scanned to assess blast performance. The results demonstrated a 4.6% improvement in recovery and a 16% reduction in dilution compared to the initial plan, and reduced exposure of people to hazardous locations in the stope. These results represent an additional value of USD 200k, gained from implementing wireless initiation to enable this particular blasting schedule.

Jan 21, 2025

By P. Ross, O. Rielo, P. Katsabanis

Selection of delay times to optimize fragmentation has been a controversial topic among researchers and blasting practitioners. The paper reviews all available experimental information, ranging from small and medium scale tests in geologic materials to small scale tests at the laboratory and synthetic materials, simulating rock. Tests have been re-analyzed and discussed in terms of the information they present and the limitation of the testing environment in representing actual conditions. New results obtained from blasting experiments in specimens made of a grout have provided a clear picture of the effect of delay on fragmentation. The grout used has a strength of 60 MPa (8700 psi), density of 2.5 g/cm3 and P-wave velocity of 4000 m/s (13100 ft/s). Each block was placed in a yoke to eliminate unwanted reflections and the desired delay was obtained using the appropriate length of detonating cord between holes or sub-millisecond electronic detonators. Delays ranged from 0.1 ms/m (0.03 ms/ft) of burden to 16 ms/m (4.9 ms/ft) of burden. Fragmentation was obtained using screen analysis of the collected fragments. Delay time has been shown to be a significant parameter affecting fragmentation and back break. Generally larger fragments and less back break was observed at short values, while fragmentation somewhat deteriorated at significant delay times, compared to what was observed at intermediate delay times. The work is now extended to include the effect of energy partition on fragmentation as well as the effect of initiation point and coupling ratio.

Jan 1, 2014

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 Javier Illanes, Felipe Moroni

In recent years, implementation of Artificial Intelligence and Machine Learning model technology has gained ground in almost every aspect of human activities. The mining industry has not been foreign to these applications, with advantages including the creation of new optimization methods and the elimination of repetitive tasks. Those applications have been implemented in multiple operative areas, from preventive conveyor belt maintenance to energy optimization for minimizing environmental impact. The blasting process aims to use the energy liberated by the detonation of explosives to break the rock mass according to specifications that facilitate the comminution process. To optimize this process, the energy delivered must correspond to the necessary amount to exceed the tensional and compressional resistance of the rock mass. If the energy applied is insufficient, the rock will not reach the desired fragmentation level and the processing plant may incur additional costs. On the other hand, if the energy level required is exceeded, we incur increased blasting costs that correspond to excess explosive used. Optimization of this aspect of the mining process has major impact in the processing chain reflected in lower costs, efficient resources consumption and environmental impact. The Design for Outcome technology (DfO), developed by Orica, is used to characterize the rock mass in detail to classify, borehole by borehole, the rock mass relative hardness to deliver the adequate energy level to achieve optimal fragmentation. This technology uses information collected by drill sensors, producing data typically referred to as Measure While Drilling (MWD) data to classify the rock mass into domains that can later be used to apply optimal blast designs. In DfO, the data flow is fully automated, starting with the data produced by the drilling system and uploaded to the cloud, which is then domained using Machine Learning (ML) techniques, and then published for consumption using a web interface. Automated explosives loading rules are then generated for each rock mass domain, ensuring that for each borehole, the adequate explosive energy is delivered to achieve the desired fragmentation results with unprecedented accuracy. The application of machine learning techniques allows us to optimize the blasting process results by leveraging a deeper understanding of the rock mass. Applying these optimization techniques, we obtain considerable economic benefits, decrease resources consumption, and achieve a more sustainable mining operation. The application of DfO in a Chilean mining operation allowed the characterization of their rock mass into four domains and established specific explosive loading rules for each one. A 60kUSD reduction in explosives cost was achieved during the test period, while maintaining the desired fragmentation results and expected dig rate. These outcomes were the result of a comparison between the blasting costs used applying the technology mentioned above and a “traditional” classification of the rock mass with the corresponding blasting practices.

Jan 21, 2025