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By Greg Wyartt

Although electronic detonators and blast initiation systems have been commercially available for several decades, uptake in the Australian mining industry has been very slow when compared to other global mining regions. The safety and operational advantages of electronic initiation are generally well understood in Australia, however there has been a prevailing perception that these advantages do not outweigh the extra financial and technical investments.

Jan 1, 2019

By Piyush Rai

Proper use of fi ring pattern vis-à-vis the blast requirements can provide optimal blast performance in terms of fragmentation. Further to this, each fi ring pattern has its own characteristic, for instance, although V-type and diagonal fi ring pattern provide same Se/Be ratio, the V-type fi ring pattern increases the opportunity for in-fl ight collision amongst broken rock fragments during their movement. Similarly straight V-type and skewed V type fi ring patterns (V1,V2 etc.) have their own characteristic strengths and weaknesses. In this light the present paper highlights the application of three different types of fi ring pattern on two different type of sandstone overburden benches of a large coalmine in India. The study reveals that Firing pattern infl uences the effective spacing to burden ratio at the time of detonation. By changing the fi ring pattern, effective burden (Be) changes and the ratio of effective spacing (Se) to effective burden (Be) during the fi ring is also subject to change in comparison to drilled spacing to burden ratio (S/B) Hence, the Se/Be ratio vis-à-vis fi ring pattern must be used to design the blast rounds. The results have been derived on the digital image analysis based fragment size characterization, excavator performance and evaluation of powder factor values on blasted muck piles. Skewed V- type fi ring yielded the best results in comparison to straight v-type and normally practiced diagonal fi ring pattern on the moderately strong sandstone benches, whereas, the existing diagonal fi ring pattern appears to be satisfactory on weak (weathered and gritty) sandstone benches. The presence of geological anomalies has also been investigated.

Jan 1, 2008

By Joshua Hoffman, Rhys Baker, Tim O’Brien

Numerous agencies in the Executive Branch of the United States Federal Government have regulatory jurisdiction over the explosives industry. These agencies develop the rules by which the explosives industry must operate, and many have the authority to enforce those rules. Likewise, there are entities in the Legislature that have oversight of those agencies and develop the laws that agencies must operate under. These entities in the Legislative Branch are Congressional Committees. Each committee has their respective jurisdictional authority over various agencies and issues. There are several Congressional Committees with jurisdiction over the agencies that govern the explosives industry and they differ slightly between the House of Representatives and the Senate. This paper discusses this division of power as it relates to the explosives industry. Each branch is responsive to the public and the processes through which each promulgates regulation and legislation require public input in different forms. Options for civic involvement for engaging each of these bodies of power in their respective processes are presented. The differences between legislation and regulation are highlighted along with the processes by which each are promulgated. A proper understanding of the governmental mechanics that affect the explosives industry are critical for the industry to be able to be proactive in playing a role in these processes in a democratic way.

By P. E. Hoffman, Joshua Ph. D.

The Institute of Makers of Explosives (IME) led a post-detonation debris collection project in conjunction with a large AN railcar detonation conducted by the Department of Homeland SecurityTransportation Security Administration, Department of Defense-Combating Terrorism Technical Support Office, Sandia National Laboratories, and the U.S. Army Dugway Proving Grounds. This important work will aid in underpinning algorithms used in the IMESAFR (Institute of Makers of Explosives Safety Analysis for Risk) Quantitative Risk Assessment (QRA) tool. The test also provided valuable data about AN detonation characteristics when it is driven to detonation. The test took place at the Utah Dugway Proving Grounds (DPG) on April 27, 2018 and the debris collection was conducted the following two weeks with an average of 20 persons per day and an approximate total of 1,400 manhours. This paper details the collection efforts, challenges, and lessons learned. It also presents some of the initial findings relating to the debris distribution.

Jan 1, 2019

By R R. Singh, U K. Dey, S K. Roy

"Commercial explosives being a heterogeneous mixture of many chemical compounds in prefixed proportion, their velocity of detonation (VOD) may vary from batch to batch, due to variations in the proportion of the chemical composition and process parameters even within their tolerance limits. Inherent limitations of measuring methods and human variations during measurement also add to the variation in VOD values determined practically. Therefore, it is customary to define a range of VOD values rather than a fixed value of VOD for a particular explosive.Variations in VOD values of four commercial permitted explosives in India were evaluated under open unconfined condition using Dautriche method and a resistance wire method based continuous VOD meter. Comparative evaluation of VOD values of selected explosives were aimed to check the relative effectiveness of continuous VOD measurement of small diameter cartridged permitted explosives using cheaper co-axial wire instead of recommended costly VOD rods along with the continuous VOD meter. Results of evaluation revealed that continuous VOD of commercial small diameter cartridged explosives could be determined using cheaper co-axial resistance cable with comparatively better accuracy than the most commonly used Dautriche method."

Jan 1, 2007

By W. J. Birch, R. Farnfield

All shock-tube based initiation systems have a time lag relating to the propagation velocity of the shock-tube itself. This paper examines the exploitation of this inherent time lag to achieve delay blasting with accuracies approaching that achievable with electronic systems albeit over a much shorter delay range. The system employed consists of a combination of standard shock-tube, plain detonators and various shock-tube branching components. The accuracy of the complete system depends on the scatter in delay time induced by each component. In order to quantify this scatter a series of trials were undertaken to determine the variability for each component. These trials are described along with a detail statistical summary of the data recorded.

Jan 1, 2009

By Roger E. Scholl

Data on off-site low-rise building damage from underground nuclear testing at the Nevada Test Site (NTS) of the United States Atomic Energy Commission (AEC) [The AEC has been called the United States Energy Research ant Development Administration (ERDA) since 1975, but because the data presented here were gathered between 1966 and 1970, the AEC rather than ERDA is referred to in this paper.] are available for seven large tests in the period from 1966 to 1970. The data, while sparse, provide an adequate sample for the investigation of motion-damage relationships. Damage in the study is statistically described in terms of the incidence of damage complaints, the incidence of buildings damaged, and damage cost. Using 5%damped response spectrum acceleration amplitude to characterize ground motion, the plotted data fit reasonably well with previous motion-damage relationships established from extensive data available from the 1969 RULISON underground nuclear explosion (UNE) experiment conducted in western Colorado.

Jan 1, 1976

By Ashlin Pillay, Osamu Iwata

Hong Kong is ranked as the world’s third most important international financial hub and attracts significant growth and development annually. The city is also known as the world's most vertical city, the most common view from your window in Hong Kong city centre is probably the window of another 30 storey skyscraper. The increasing demand for real estate in this bustling Metropolis has placed immense pressures on its transportation infrastructure because whilst the construction continuously grows upward with larger and larger skyscrapers, it leaves the transportation planners with very little choice but to go underground. As a first world city, interrupting daily business operations is simply not an option; however, of even greater concern is the safety of these 8 million residents. Blasting Regulations are under the strict control of the Mines Division showing zero tolerance to the breaching of safety standards. The Ho Man Tin Station (HOM) excavation, a part of the Kwun Tong Line Extension (KTE) project situated in Hong Kong began in June 2012 and is one such project that is under strict regulations from the Mines Division. The HOM project is a cross cut interchange station between the Kwun Tong Line Extension (KTE) and Shatin Central Link (SCL).

Jan 1, 2015

By Sarah Guzzelli, Enrigue Munaretti, Anneliese Botelho, Jair Koppe

Drill and Blast (D & B) is one of the main operations in the mining production cycle, which aims to fragment rock according to a pre-defined plan for proper loading, haulage and processing specifications. In this sense, data from a Brazilian iron ore mine was analyzed, given emphasis on blasthole length, subdrilling and stemming. The D & B report, including mining data such as number of blastholes, length, and diameter and stemming aspects, was analyzed in order to be able to compare these results with the blast design. The study showed significant differences between the designed blasting pattern and that one obtained by the operation. As a consequence, problems such as inadequate fragmentation, incorrect size distribution and loss of energy, were identified. For example, when stemming has a different length than it should have, noise and flyrock can occur, including inadequate fragmentation and vibration in both situations. Therefore, a comparison between the usual D & B procedures and recommended D & B design based on literature reveals the most important deviations and their consequences. The study intends to identify solutions for simple problems, improving D & B operations and safety practices.

Jan 1, 2014

By Andrew F. McKown

Overbreak and damage to rock walls at the perimeter of rock excavation can lead to safety problems due to rock falls and additional costs due to a] extra mucking, b] extra concrete or shotcrete to backfill overbreak, c] additional rock reinforcement, d] additional water inflow and e] additional maintenance of rock walls. To minimize these undesirable effects, there are several perimeter control techniques available (i.e. line drilling, cushion blasting, pre-splitting, smooth blasting, and fracture control blasting) which control perimeter hole spacing, burden and loading to provide a smooth, stable excavation contour. Conventional perimeter control loading and hole spacing is satisfactory for massive, homogeneous formations, but when blasting in weathered or fractured rock closer spacing and very light loading is required.

Jan 1, 1984

By R L. Keller

Hong Kong has some of the most restrictive practices regarding blasting than any place in the world. Regulations regarding vibration limitations are 1 in/sec for structures and 0.5 in/sec (or even less) for most utilities; with no recognition of frequency response or adjustment. The Hong Kong Geotechnical Engineering Office has one of the most conservative approaches and protective guidelines for pre-blast assessment of slopes subjected to blast vibration (SEE paper '96). The protective measures to control flyrock generally required by the Mines Division are additionally very stringent. It is not uncommon for the costs associated with protective measures or methods which must be employed to exceed the cost of the drilling and blasting itself - or to waiver blasting application unfeasible altogether. From these restrictions it can easily be imagined how blasting in this urban environment would be most challenging.

Jan 1, 1997

By James Ludwiczak

We are coming to an end of an era in Midwest surface coal mining. For many years, large tracts of coal lands were readily available for sale or lease to surface mine operators.

Jan 1, 1980

By D Larson, M Finger

Chemical explosives may become a key element in many of the in situ energy and mineral recovery methods under development. This paper discusses the potential role of explosives in deep rock mining for resource recovery. Several energy and mineral recovery programs described are an outgrowth of the Plowshare Program and Explosives R&D conducted as part of the AEC/ERDA mission at Lawrence Livermore Laboratory. Several important aspects of the use of explosives in deep rock mining are reviewed. First, the status of knowledge of deep rock fracturing to create permeability underground is discussed. Completely contained blasting has not been a widely applied tool used in the mining industry. We conclude that data available on deep rock fracture is minimal and that the mechanisms that control the processes must be understood before technical and economic feasibility can be established. We also discuss the unusual problems in the selection of an explosive or blasting agent for deep rock applications including emphasis on the functioning at depth and safety aspects. Finally, a brief review of similar activities within the U.S. is given.

Jan 1, 1976

By Bob de Raadt

For a long time industrial underwater blasting has stood in need of a calculation method, for the determination of shockwave-proof as well as shockwave-effective charge distances to objects in water. After a brief discussion of the physical background of the shockwave mechanism in water, the author discusses an empirical theoretical computing method based on the "Bubble boundary" concept. The practical application of this model is finally shown in an account of a few underwater blasting operations in which charge weights of c.1-1000 kg were involved.

Jan 1, 1980

By Norman Paley, Zachary Pickett

The Red Dog Mine is a high-grade zinc-lead mine located in northwest Alaska which began operations in November 1989. In June 2014 the upper half of a charge in a trim shot in the Aqqaluk pit deflagrated. No other holes in the area were observed to react and the remainder of the pattern was shot without incident. This was the only known case of a deflagration in the 25 years of operations. As part of the investigation into the cause of this incident rock samples were obtained from the area of this hole and from other areas in this pit. The samples were assayed and tested for reactivity using the Reactive Ground Catalyzed Adiabatic test. Approximately half of the samples were found to be reactive with standard blasting agents. Unexpectedly, some of these were found to be reactive with blasting agents doped with urea to act as an inhibiter. Relationships between element grades and reactivity and between Specific Heating Capacity and reactivity were developed; however, the small sample size led to these models having an unrealistically large number of geological model blocks tagged as reactive. A program to better understand the behavior by testing more samples was initiated. Drill core was selected based on the predicted level of reactivity using the aforementioned relationships. The samples covered a greater range of grades and lithologies and included rock from the soon to be developed Qanaiyaq pit. The samples were dry pulverized then split for elemental assay, Reactive Ground Catalyzed Adiabatic testing, Specific Heating Capacity (SHC) determination, and X-ray Diffraction (XRD) mineralogical analysis. From this data, a Red Dog Mine specific assay based classification for separating reactive from non-reactive ground was developed. Furthermore, it was possible to divide the reactive ground into two subgroups: i) rock which reacts with ANFO-emulsion blends even when manufactured specifically with a reactivity suppression agent like urea and ii) rock which reacts with ordinary ANFO-emulsion blends only when a reactivity suppression agent like urea is absent.

By John N. Jr Edl

Geokinetics, Inc. has pioneered an in-situ oil shale retorting production process that provides the requisite void space for producing a permeable rubble bed, within the retort zone, by using the explosive energy from vertical blastholes to lift the overburden. By installing suitable instrumentation on the surface of the overburden over an appropriate blasting pattern, it is possible to obtain estimates of the average radius of gas penetration around the blasthole and the average volume, per unit length of blasthole, that is actually occupied by the explosively produced gases (which includes both the volume of the cracks that are penetrated by the gas pressure and the deformed blasthole volume). It is expected that these estimates can be used to examine, and quantify, the effects of such blast design parameters as the type of explosive, the blasthole diameter, the geometry of the explosive charge (length to diameter ratio), and the relative timing of sets of charges.

Jan 1, 1983

By Malcolm Mellor

Practical procedures that have been developed for pre-split blasting and smooth blasting in common rocks are reviewed systematically. Topics covered include shothole spacing, charge weight per unit length of shothole, decoupling ratio, adjustments for explosive type and rock type, and weight of explosive per unit face area. Relevant properties of frozen rocks, frozen soils, and ice are compared with those of common unfrozen rocks, and appropriate adjustment of blast design is discussed. Interim relationships for the design of controlled perimeter blasting in frozen soils and massive ice are put forward, recognizing that additional experimentation is required. Special problems in controlled blasting of ice are discussed. These include effects of wet holes, delayed removal of burden, and submerged burden. Special attention is given to the cutting of ice islands and icebergs. An Appendix describes an operation in which the face of an ice wharf at McMurdo Sound was trimmed by pre-split blasting.

Jan 1, 1976

By Robert Hopler

Complying with our request in the February issue of the AGRICULTURAL BLASTER for items that would be of interest to other blasters, Mr. Thomas H. Benton of Tennessee sends us an article in which his methods of securing contracts are explained:

Jan 1, 2013

By Paulo Couciero

Since explosives are the source of all energy used for rock blast fragmentation and heave, multidimensional effects in the detonation driving zone become essential to better describe the detonation process. In order to use the explosive as an energy source-information for more realist blasting performance simulations, a simple and effective modelling strategy is desirable. Facing this challenge, an engineering approach to two-dimensional unconfined non-ideal detonation is proposed. Based on the elliptical construction of the shock locus, the model combines the axial cylindrical stick Q1D solution with some additional limiting conditions to determine the sonic edge of the charge. For a given set of rate law parameters and velocity of detonation, a complete axial solution is firstly computed through the Q1D model. From this solution, a vital relationship between the axial shock curvature with the shock shape parameters can be stablished. Once this relationship is found, the problem simply reduces in finding the shock shape parameters subject to the sonic edge condition. As a result of this calculation, the corresponding charge diameter can be found. Consequently, the proposed model can map the diametereffect curve by relating the unconfined velocity of detonation with its corresponding diameter. Finally, because of its low computation cost, the proposed engineering approach can be also used for characterizing the rate law parameters by fitting to data from unconfined detonation experiments

Jan 1, 2019

By B de Raadt

After discussing mechanisms of collapse for the explosive demolition of towers in general and cooling towers in particular, author comments upon a blasting operation in which four cooling towers were involved. The intention of this paper is to present reliable parameters, generally valid for the explosive demolition of reinforced concrete cooling towers.

Jan 1, 1978