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By Robert C. Fouchard, Gordon Chalmers, David E. G. Jones, Ivana Alilovic, Phillip D. Lightfoot

There have been numerous international instances over the last several years in which pumping emulsion explosives has resulted in accidents, apparently as a result of increased thermal sensitivity under these conditions. The key questions for the explosive industry are (1) what are the parameters that influence the sensitivity of emulsion explosives and, (2) how do these various parameters interact. To address the sensitivity of emulsion explosives to various parameters, a study was undertaken using an accelerating rate calorimeter (ARC) and a heat flux calorimeter (HFC). The effects ofthe addition of ammonium nitrate (AN) prills and different grades of aluminum (Al) on the thermal behaviour of emulsion explosives were determined. Additionally, changes in pressure, atmosphere (inert or oxidizing) and sample vessel material were assessed for their impact on thermal sensitivity. Addition of AN prills, fine granular Al or atomized Al did not affect the onset temperature for exothermic decomposition, so that the maximum “safe” temperatures for emulsions containing these additives will be similar. There were differences in the rates of self heating, however: AN prills decreased the rate of self heating, whereas atomized Al increased it. The emulsion formulations containing atomized Al produced small holes in titanium vessels. This phenomenon did not occur in Hastelloy C vessels, providing a reminder that materials of construction need to be carefully considered for equipment used to manufacture or handle emulsion explosives.. Both ARC and HFC experiments gave lower onset temperatures in air than in argon. We attribute this to oxidation of the oil phase by air. This result is significant for dry-running pumping conditions, where emulsion is heated in the presence of excess air.

Jan 1, 2000

By Larry R. Fletcher, Virgil J. Stachural, Matthew N. Plis

The Bureau of Mines is conducting research on blasting methods that reduce highwall overbreak and the associated rockfall hazards. This paper presents the results of a series of tests to improve presplitting at a western surface coal mine. Reductions in overbreak were achieved by decoupling and/or repositioning the main explosive charge in the 10-5/8 inch presplit blastholes that formed the highwall. Blast designs are presented by the authors for 1) repositioning the explosive charge from a weak rock layer to a stronger rock layer, 2) decoupling with cardboard tubes in the toe region, and 3) suspending bagged powder at intervals along the length of the blasthole. About the same total quantity of explosives was used in all three test designs. It was readily apparent from periodic visual examination and photographic surveys of the highwalls that the amount of rockfall was reduced, and with a longer delay before rockfalls began, in all test areas.

Jan 1, 1991

By Sean Cahill

The Blasting In the summer of 1999, a Southern California drilling and blasting company conducted blasting as part of the grading operations at the Highlands Ranch development in San Diego, California. Highlands Ranch was a new single family residential project located near older residential properties in the area. Blasting was necessary to remove indigenous meta-volcanic rock associated with the local geology.

Jan 1, 2003

By William H. Snyer, Hank Cox

A high explosive device using Linear Shaped Charge (LSC) (to rapidly cut vent and drain openings in a rail tank car) is described. In the event of damage to a tank car loaded with a pressurized flammable fluid, it may sometimes be necessary to perform controlled on-site vent, drain and burn operations. Existing techniques required refinement to achieve the desired safety and procedural reliability for use in emergency situations.

Jan 1, 1994

By Hubert den Dikken

ache, especially when it comes to forwarding of small quantities. Air transport is limited to 1.4 explosives on cargo aircraft and 1.4S classified explosives on passenger aircraft, so most samples cannot be transported by air. Ocean transport is a possibility, but due to stowage and segregation regulations of the IMDG code, a very expensive one. Road transport is often the only solution, but high explosives require special trucks with licensed drivers. The solution to these logistic problems is solved by creating a 1.4S (Class C) classification for all high explosives, when packed in special containment vessels.

Jan 1, 1995

By Orica Chile, Orica Brasil, Orica Brasil Victor Morais, Kinross Paracatu Leopoldo Muñoz, Kinross Paracatu Luis Marinho, Gubio Barsottini, Orica Brasil José Vergara, Lucas Steffen, Orica Brasil Washington Vilas

In drill and blast activities, it has been a challenge to sculpt walls accordingly to what has been designed in state-of-art mining design software. Obviously, the perfection of making neat and smooth walls – using aggressive sources of energy, like explosives – are time-and-money consumable and, sometimes, even unnecessary. But undoubtedly, it is vital to guarantee solid walls, safe operations environment, beyond to avoid ore losses and pit constraints caused by poor rock breakage on detonation. Kinross Gold Corporation owns the biggest Brazilian Gold Mine, located in Minas Gerais state. Morro do Ouro mine has reached over 30 years of operation, and due its mature age, the complex has developed its pits, becoming them deeper and surrounded by high walls.

Feb 6, 2023

By Ken Roosa

Blue Circle Atlantic of Ravena, New York, operates a four million ton per year quarry. The quarry management objective is to maximize crusher throughput tonnage while optimizing the aggregate cost to drill, blast, dig, haul, and crush a ton of rock. To meet this objective, Blue Circle,s blasting program combines, large diameter production blastholes with medium diameter satellite blastholes.

Jan 1, 1989

By Jesús V. Saccsa, Kenji B. Loayza, Erick M. Condori, Jorge A. Velásquez

This research investigates how to reduce manufacturing costs of a safety fuse composed of black powder, replacing its ingredient NO3K by NO3Na for processing, and contributing to minimize costs per blasting.

Jan 1, 2017

By Raúl Mondaca Aracena

Mantoverde mine requires increasing its production level to double. EMTS - Projects performs far and near field vibration studies to make changes to the D&B design and sequences, in order to equalize the current vibration levels, applying massive blasting in its process.

Feb 1, 2020

By G Dean Barrett, Ed Jr Smith, Calvin J. Konya

The purpose of the project was two fold: 1. To determine whether Pyrodex, a propellant, manufactured by the Hodgdon Powder Company, could be used as a substitute for high explosives for presplitting in granite and other materials. 2. To determine if Pyrodex, a slow reacting propellant which produces no stress waves in rock because it reacts subsonically, could cause the rock to crack similar to the results achieved with high explosives.

Jan 1, 1986

By Joshua Micah Hoffman

While it is easy to state that meaningful involvement of the community can play a critical role for a successful blasting operation, following through with this involvement is not an easy task. Structured Public Involvement (SPI) is a developed protocol for involving communities in project planning decisions and could be readily applied to the blasting industry. SPI was developed for the purpose of collecting quality public input about public transportation projects. The purpose of SPI is to bring about stakeholder satisfaction with potential projects by allowing controlled input from the stakeholders. It was designed and intended for democratic societies that have come to expect a voice in public projects. While blasting operations are not always in the domain of public projects, the fundamental process outlined by SPI can be useful for collecting feedback from the immediate public around blasting operations.

Jan 1, 2014

By Bengt Ljung

Manual charging of long upward drilled holes in mines is a heavy and risky job today. Mechanization of this work has been requested for some time by miners, their supervisors, industrial safety organizations and the trade unions, all of whom are interested in improving the working environment. This paper presents newly-developed charging systems intended primarily for charging in connection with sublevel caving and sloping. These systems have been field-tested during 1977 in the LKAB mines in northern Sweden. The results of these field tests and the results of laboratory work conducted to help eliminate the risks involved in charging explosives are also discussed. The equipment being tested (see fig. 1 and 2) consists of a charging vehicle with articulated steering, the PT-60, which has been equipped with a hose feed system mounted on the hydraulic extension boom. From a sheltered position, the operator brings the detonator and primer to the hole opening, after which the hose is pushed in mechanically to the end of the hole. Measuring equipment indicates when and if the end of the blasthole is reached. The operator then withdraws the hose mechanically as charging takes place.

Jan 1, 1978

By Pierre Mousset-Jones, Geraint W. Harris, Robert Karlin, Jaak Daemen

In order to minimize the ore dilution induced by blast movement in surface mines it is necessary to quantify such movement. This will make it possible to more accurately locate the grade boundaries on the surface of a blasted rockpile prior to excavation. This paper describes the development and testing of a method to accurately measure the direction and magnitude of sub-surface blast movement. The technique involves the use of magnetic "radiometry, using a cesium vapor "radiometer and real-time differentially corrected, GPS system, to locate the post-blast position of magnetically enhanced target objects, whose pre-blast locations are known, without disturbance of the blasted rock. The objective is to design an accurate and efficient technique which can be integrated into a mines production cycle.

Jan 1, 1997

By Walt Meglasson

"Developing technologies in demolition equipment and processes have produced a newsophistication within the demolition industry. Yet, with increasing frequency, owners,architects, engineers, and contractors reject out of hand one of the safest and most effectivetools in the demolition industry today, specifically the use of explosives and blastingtechniques in man_made structure removal. The use of explosives in any application mustbe considered as a tool, no more or less dangerous than any other type of tool, when usedproperly. Accordingly, importance must be attached to recognizing the skill, integrity, andcare of those who use it. Massive amounts of information and help are available to assistthe rock blaster, ranging from the practical to the highly theoretical, but very littleinformation exists to guide anyone considering unleashing the power of explosives instructural demolition blasting. The planning and work required to execute such projects iscomplex, and the recognition of the different applications explosives can be applied to isthe first step."

Jan 1, 1993

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

By Jonathan Zimmerling, Rob Alkins

The model of waves emanating from a blast hole proposed by Heelan, and further developed by Blair and Minchinton, provides an approximation of particle motion in an isotropic, continuous and homogenous medium caused by a cylindrical pressure source. Previous work in the literature shows that the shapes of the peak strain and peak particle velocity contours generated by this model are influenced by priming location. This paper presents the results of experimental investigations into the effects of priming position in an explosive column and the resulting shape of the surrounding stress and particle velocity fields. Fifteen emulsion charges were detonated in a limestone quarry, of which eight were bottom primed and seven top primed. The charges were fully confined, with no breakout to any surface. Particle velocity was monitored using tri-axial sensors coupled to the rock using cement, and pressure sensors were placed in water filled boreholes for fourteen of the experiments. Statistically significant differences in peak pressure for bottom and top primed shots were observed. Blair and Minchinton developed two pressure source functions, one of which is scaled using the charge weight scaling law. New models of the explosive pressure source are developed and compared to those found in the literature. These models are directly calibrated by predicting the peak velocities achieved at the known locations of the velocity sensors, then minimizing the residual sum of squares between the predicted and observed peak vibration values. Due to the complexity of the model the residual sum of squares cannot be minimized using standard non-linear optimization techniques, so a stochastic, agent based global optimization method is employed. Models are then cross validated by comparing the relative predicted differences in stress between bottom and top priming position to the observed differences.

Jan 1, 2013

By Farshad Rashidi Nejad, Ali Asgari, Sanaz Norouzi

Blasting is known as the first step of rock breakage in mines. An indication of the importance of blasting is that more than 1 billion kg (2.2 billion lb) of explosives are used annually in Australia and 3 billion kg (6.6 billion lb) in the United States for rock breakage, more than 85% of which is used in the mining industry. The notion that blasting, as the first step of comminution, plays a significant role in crushing and grinding energy consumption is not an unfounded thinking. It can be noted that the comminution electrical energy consumption decreases in these ways: First, if the feed size to the primary crusher is decreased, less energy will be required to crush the ore to the same product size. Second, a decrease in work index (Wi) related to additional macro fracturing and micro fracturing within individual fragments.

Jan 1, 2015

By Javier Castaneda, Luis Zozaya, Noel Huarachi, María Rocha

The objective of the project was to implement and calibrate drill and blast models supported by Geotechnical and Geological models as well as the mine and operation characteristics. The models would then be migrated to HxGN Blast to ensure a productive process that is simplified, digitized and optimized.

Feb 1, 2020

By John M. Feasler

Since the advent of NONEL shock tube, the signal transmission invention developed by NITRO NOBEL AB of Gyttorp, Sweden, we have seen the following application in the United States: (1) NONEL PRIMADETS - Non-Electric Blasting Caps for underground use, available in long period delay and millisecond delay intervals. (2) H.D. NONEL PRIMADETS - A rugged model of the underground unit designed primarily for use in quarries, coal strips, and open pit mines.

Jan 1, 1977

By Cam B. Grundstrom

This paper will describe blast design modifications that have been made at the Island Copper Mine, near Port Hardy, British Columbia. To date, two additional designs have been implemented in an effort to reduce final wall damage and increase productivity. The typical blast patterns in use at Island Copper were monitored in an effort to build up data to which new designs could be compared.

Jan 1, 1994