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By Calvin Konya, Anthony Konya

Presplitting is a form of blasting that when executed properly will create a smooth wall that will minimize secondary conditioning. In recent years, presplitting has become a popular technique to be used in both the mining and construction industries, however, presplitting fails on many occasions because of ‘geologic conditions’. This is typically because of improper explosive loads consisting of overloading and underloading blastholes. In this paper the authors introduce new factors such as a presplit factor which varies for different rock types, selection criteria for the spacing of presplits, and the optimization of explosive load for the technique of Precision Presplitting.

Jan 1, 2017

By Jonathan D. Aubertin

The unique nature of rock salt blasting is compared to traditional hard rock practices. Rock salt geomechanical nature is discussed in the context of rock blasting events. A cratering mechanism prevalent in soft rocks is presented and exemplified through a series of single hole blast tests performed in salt deposits.

Feb 1, 2020

By Mark Roberts

Automation, data analytics and optimisation are key trends in the mining industry. Doing more, and better, while expending less resources targets KPIs around efficiency and productivity. With the explosion of data, the next step is to develop an optimal level of processes and systems to harness this data to support value-in use decisions. Typically, significant amounts of resources and effort are invested to develop realistic simulation models. However, models are frequently not integrated with existing systems, and therefore are underutilised. When we consider the specialised process of blasting, integration with upstream and downstream processes is a significant driver to realise sustained improvements and value. The application of genetic algorithms and cloud computing to solving complex mining problems has advanced over the last 15 years, in particular with mine scheduling. Genetic algorithms are unique in that they support true multi-objective optimisation, utilising population-based methods to present trade-offs between multiple solutions. Secure in-cloud processing speeds up the processing, with results delivered in timeframes that are not feasible with desktop computing.

Feb 6, 2023

By J P. Tidman, I J. Kirby, G H. Harries

The SABREX computer model is based on the fact that both shock waves and gas pressure are important in describing a blast. The treatment of explosive-rock interactions includes the influence of non-ideal detonation to make use of recent advances in that field. Details of the blast layout are defined from a comprehensive list of conditions the blaster can control (drill pattern, charging and hook-up). The program gives practical and graphic information about fragmentation, muckpile, damage and costs.

Jan 1, 1987

By W. Boas, R. Silva, D. Yumi, L. Steffen

The continuity of the flow and stages within the mining process is essential to achieve success in its operation and results, especially when it comes to a gold mine. During the first seven months of 2022, crushing at the Morro do Ouro Mine had 19 stops in the primary crusher due to equipment blockage/obstruction, this could be due to the size of the material that was blasted with explosives and fed. The feeding of coarse material to the crushing plant impacts the operation in several ways, for example, premature wear of the equipment, reduction in the supply of the remainder of the beneficiation, reduction of the buffer pile and damage to the conveyed belt. In a mine located far from the community, the fragmentation improvement is mainly related to load increments or some other relatively simple change. However, when it comes to a mine located close to communities, alterations of this type must be analyzed in detail, as it can have an impact mainly in relation to vibration and flyrock. Aiming to improve the efficiency of the blasting, mainly in relation to the result of fragmentation, a project was created to improve the efficiency of the blasting with a focus on reducing the crushing stoppage and reducing the amount of material discarded due to inadequate granulometry. During the evolution of the project, several improvement solutions were proposed, for example adjustment of the power factor in relation to the geological characteristics of the rock mass, drainage, blasting geometry, vibration reduction techniques and several operational improvements. By using the techniques and methods identified as improvements during the project, it was possible to observe and quantify improvements in relation to the fragmentation of the blast. During the months of January to July 2022 there were 19 events. It was estimated that at this rate there would be 14 more blockage events, but there were only 3 events and that meant a 79% reduction in blockage. In addition to the reduction in crushing shutdown events, there was also a 53% reduction in the amount of ore that is discarded due to inadequate granulometry and, with that, the feed rate of the grinding system was able to reach the maximum feed limit due to the material being fed to the mill well fragmented, contributing to increase the production and productivity of the beneficiation process at the Morro do Ouro Mine in Paracatu-Minas Gerais-Brazil.

Jan 1, 2024

By Alejandro Ferrada Vergara, María Jesús Barros Godoy

The need for a basic method for selecting explosives based on rock mass or intact rock properties for mining and construction arises from the limited consideration given to these factors when choosing among products and also an implicit overestimation of the explosive power to fragment the rock. This study highlights the importance of evaluating different properties such as rock strength, deformation, fracturing, detonation velocity and energy release when selecting explosives. The concept of characteristic impedance, which considers rock strength against shock waves generated by explosive detonation, is introduced. Understanding this concept is crucial for assessing explosive behavior according to various rock types. The study concludes with a practical guide table that categorizes rock properties and provides recommendations for selecting explosives based on rock mass and rock properties. However, it is important to consider other relevant factors, such as the presence of water or nearby instabilities, which can influence the final choice of explosives.

Jan 21, 2025

By William Reisz

Many different types of drills coming in a wide range of sizes and configurations are used in the blasting industry today. While each system may have its own unique attributes and capabilities, it may hold its own perils as well. This article will focus primarily on hazards that are mutual to most every type of drilling system.

Jan 1, 2013

By K. Hausmann, P. A. Sashin, G. J. Prejean

Misfires caused by unreliable shock tube constructions can have significant cost implications and place field workers at serious risk during remediation. Ionomer materials, used as a subtube in shock tube constructions, provide superior hot tack strength, oil resistance, impact resistance at cold temperatures and excellent thermoformability properties. These are important features for resisting blast-throughs and ensuring blasting reliability in demanding environments, such as open pit mining in harsh environments. Superior hot tack strength, strain hardening, and excellent thermoformability properties of the ionomer materials ensure uniform powder distribution along the shock tube during construction and avoid undesired powder accumulation due to deformation or vibration during use. Oil or chemical resistance is another feature of Ionomers. This allows improved property retention in contact with oils and hence longer sleep times of the shock tube. Another feature of these highly engineered ionomers is superior impact strength at low temperatures. This plays an important role considering the resistance to fly rock impact in open pit mining operations in particular in cold climates.

Jan 1, 2011

By Andre Pienaar, Larry Wilson

Destruction of waste emulsion by blasting has been proven to be risky and disastrous incidents have been seen when using this practice. Our R&D department in conjunction with Lake International has developed an emulsion breaker system where underground waste can be destroyed safely. The methodology and logistics around the system will be demonstrated during the presentation. This process offers a safe alternative for the removal of sensitized and un-sensitized waste products from these mining environments.

Jan 1, 2010

By Michael Wieland

The work principle from thermodynamics is used to model the shock and heave for explosives shot in rock or under water, with the latter compared to reported results. The work principle utilizes restrictions and constraints to yield a representative fit to the irreversible (natural) shooting process. The reduction of the internal energy of the reaction-zone yields the total expansion work (TXW), the resultant sum of the rock/water shock and heave. The restoration technique of forming a closed thermodynamic loop yields the reversible mechanical work (RMW) or the rock/water heave. The residual work that remains when RMW is subtracted from TXW yields the irreversible disorder work (IDW) or the un-dissipated (without loss) shock in the surrounding rock or water. The work principle renders an unequivocal relationship for the shock-loss factor, rather than the traditional roundabout formula for correcting the underwater gauge-shock of un-modeled explosives. There’s a novel heave-ratio factor that unquestionably rates the fit of results under comparison. Rock-shots are more complex in nature than underwater shots due to rock fracture and stratum rupture, though numerical resolution is worthwhile. The proposed rock-water-jelly (RWJ) model yields rough estimates, with rock-type results not wholly different from their underwater counterparts. Though reported underwater shots reveal shock and heave trends with respect to charge formulation ingredients, there are no such rock-shot results for comparison, since the relevant test measurements in rock remain difficult, if not intractable.

Jan 1, 2007

By Natalie Zeleznik, Brian Hawkins, David Bradley, Rachel Gooding, Patrick Wilson

"The United States (U.S.) Department of Homeland Security (DHS) Directorate of Science and Technology (S&T), utilizes a probabilistic risk assessment (PRA) approach to explore the risks (anduncertainty) from chemical, biological, radiological and nuclear (CBRN) threat agents to the Homeland.This end-to-end risk methodology considers a broad range of hazards incorporating emergingtechnologies, available countermeasures and input from the Intelligence and Law Enforcementcommunities (IC/LE) to evaluate the acute risk to human health due to an attack on the U.S. homeland. The PRA generated output provides a mechanism to examine risk mitigation strategies, critical vulnerabilities, critical data and knowledge gaps and relative risk rankings of materials, targets, classes of compounds and scenarios."

Jan 1, 2017

By S. Behera, K. Dey

This paper presents a methodology for finite element (FE) modelling to analyse the total deformation of rockmass under blast-load, with a focus on predicting backbreak that may occur during surface blasting operations. Backbreak can result from improper use of explosive energy, leading to damage beyond the excavation zone and jeopardizing operational safety and productivity. The paper highlights the impacts of backbreak on bench stability, excavator operation, drilling operation, flyrock generation, and improper fragmentation and boulder formation in surface blasting. However, prior estimation of extent of rock breakage zone can provide an idea to formulate the blast design to control the backbreak. While vibration-based prediction models are commonly used to estimate backbreak, they require physical blasting experimentation. To overcome this limitation, the paper describes the development of a FE model using ANSYS Explicit dynamics, which simulates rock blasting and calculates the total deformation of the rockmass. The rockmass deformation is modelled using Drucker-Prager (D-P) strength model with the Jones-Wilkins-Lee (JWL) equation of state for the explosives. The accuracy of the FE model is evaluated through physical experiments, and the results are compared with the vibration models. The FE model demonstrates close proximity to physical observations as well as vibration model result in predicting backbreak, thereby offering a promising alternative to vibration-based prediction models. The primary objective of the study is to predict the response of the insitu rockmass to explosive blast loading and determine the effective rock breakage zone.

Jan 1, 2024

By Hairong Zeng, Shahram Tafazoli, Edmond Chow

Blast fragmentation is one of the main parameters for optimizing mineral processing, but reliable data is difficult to acquire, resulting in unpredictable performance and efficiency. Crusher and grinder circuits are designed to process specific rock size ranges. Oversized rocks require extra energy to reduce before feeding into the process, and undersized rocks indicate that the process is not used to its full extent. Blast design is the key to controlling the blast fragmentation, so the ability to accurately monitor the particle sizes is imperative.

Jan 1, 2011

By Tapan Goswami, Stephen Jeric, Geoff Brent

Highwall failures in large deep open cut mines have very significant safety and commercial implications. There are many factors influencing the stability of highwalls. The major influence is the interaction of the local geology with the shape of the pit wall. This factor is in the realm of the geotechnical engineer and is beyond the control of the blasting engineer. However, a secondary influence is the blastinduced damage to the wall. In most open cut metal mines the blasting strategy to control this damage involves the use of separate production and trim blasts bounded by presplits at the final wall.

Jan 1, 2011

By Gerald R. Coonan

Early in the open session of the 1979 SEE Fifth Conference panel discussion, someone asked a question of the panel concerning the future intent of the Office of Surface Mining and the regulatory limits established for ground vibration and air blast. The "gist" of the question was: "What assurances do we have that OSM will not promulgate a limit of 0.5 inch per second ground vibration, or some other number within the next two years or so."

Jan 1, 1979

By John W. Brown

During the summer of 1994 the mining industry experienced numerous accidents involving blasting related incidents. The Tri-State Chapter of Explosives Engineers planned a meeting to discuss three of these accidents.

Jan 1, 1995

By Jaak J. K Daemen, Clayton R. Morlock

A study was performed to evaluate the predictability of airblast overpressures induces by production mine blasting. Thirty-seven production blasts were monitored using 3 blasting seismographs giving over 100 blast overpressure records. Blasts were monitored at 5 coal highwall operations and at a limestone quarry, all in the midwest. Blasts consisting of small surface charges were monitored to permit an assessment of prediction methods under controlled conditions, as well as to observe actual delay intervals and their influence on the overpressure.

Jan 1, 1983

By W. J. Birch

The dedicated documenting of blast design and vibration monitoring results forms part of the best practice methodology for today’s blasting operators. This allows regression curves to be constantly updated and in turn compatible charge weight determinations are based upon the most current data. The point can arise however when so much data becomes agglomerated that variations in blast design, geology or monitoring location response and their effects can pass unobserved and start to have an adverse effect on the forecasting capability of the regression due to a deterioration of the standard error statistic. The simple solution would be to only compile like-for-like blasting returns, but this prospect can quickly become unworkable due to the number of potential variables. In addition it is very difficult to spot subtle variations by simply examining a standard scaled-distance curve mainly due to the intrinsic data scatter that is always present together with the logarithmic nature of the regression curve. If indeed a variation is thought to be apparent, how can the degree and magnitude of its influence to be quantified? The Likelihood Ratio Test when applied to regression data can diagnose subtle variations between data sub-sets and provides a comparative statistic as to the degree of variation. By analysing datasets in such a way, levels of compatibility are obtained, indicating which sets can be combined in order to increase prediction capability.

Jan 1, 2004

By Gary Anderson, J. P. Remi Proulx

Rio Tinto’s Colowyo Coal Mine produces 2.1 million tons per year in northwest Colorado. Colowyo uses the terrace mining method to recover up to seven coal seams ranging in thickness from 5 to 20 feet. Coal recovery in the 6 foot thick high grade C-seam has recently been challenged due to large variations in the pitch and roll of the seam. As well, some coal damage was seen due to an increased thickness of the overburden consisting of a hard sandstone channel.

Jan 1, 2012

By Shao Li, Chen Zhiming, Wu Jihong

In this paper,powder emulsion explosives,which have high sensitivity and strong detonation force,have been studied by applying emulsion technology to the production of the present powder ones.Under the condition of #8 industrial detonator initiation,the distance of air gap propagation is 110~180mm,brisance !3.5mm, lead block test value 325ml and detonation velocity 3000~4000m/s for small diameter (35mm) explosive cartridges.In addition to these,the factors effect on are investigated by experimental study and theoretical analysis.

Jan 1, 1991