Search Documents

By P D. Katsabanis, W Roberts

Commercial explosives exhibit non ideal behaviour which is very difficult to model. The fume spectrum produced by commercial explosives apart from its practical significance for underground mining is of great theoretical importance since it reveals information about the chemistry of the detonation process. Emulsions, watergels and dynamites were tested under various degrees of confinement in an one cubic metre closed chamber. Sand, concrete, steel and copper pipes were used to alter confinement. The degree of confinement was found to significantly influence the quantity (litres/kg of explosive) and the relative proportions of toxic and non-toxic fumes (percent of total fume measured). These results lead to further confinement testing using various rock materials. Fume results, and thus detonation performance were found to be dependent on the type of rock material used for confinement. Materials such as dolomite, limestone, and granite were found to result in a relatively high detonation efficiency of the subject explosive as shown by the distribution of detonation fume products. Conversely materials such as sandstone, talc and massive sulphide resulted in fumes suggesting low relative detonation efficiency. Fumes appear to be a sensitive indicator of the completeness of reactions occurring within the expansion zone of the composite emulsion explosive, while the detonation velocity is relatively insensitive to small variations in confinement. Estimates of sonic velocities of the confining rock materials were found to show no correlation with VOD results. However good correlation between fume results and sonic velocity suggests that the performance of an explosive as indicated by the resulting fume spectrum is affected by the degree of confinement.

Jan 1, 1992

By D K. Joyce

Large diameter boreholes have become increasingly popular in underground mining. Drilling equipment can drill full rings, including vertical upholes. Special techniques are required to load upholes of three inch to eight inch diameter. The current methods for loading AN/FO and bulk or packaged emulsions are described.

Jan 1, 1988

By Sharon K. Reamer, Yvan Sifre, Klaus-Gunter Hinzen

"Three case studies are presented that illustrate the successful application of firing timeoptimization (hybrid modeling) in the quarry environment and for a construction site. In allcases, the method requires the measurement of at least one in situ, single hole explosion asa representative model of the desired blast design."

Jan 1, 1993

By G E. Exedaktylos, Y Zhou

The complex and non-linear nature of blast fracturing has restricted common bract design primarily to empirical approaches. The code developed for this investigation simulates the pattern of interacting radial fractures from an array of blastholes, at various burdens and spacings, and in simultaneous and delayed modes. The resultant pattern is analyzed and a fragment adze distribution calculated.

Jan 1, 1989

By Zoltan Susanszky

This paper discusses problems encountered when blasting under rivers for pipeline crossings. Many pipelines have recently been laid under the Danube River. Great care had to be taken to determine limits of detonation impulses from blasting operations in order that no damage would occur to structures at the water's edge, boats, and swimmers. Equations were derived from the results of this study which enable prediction of impulse levels.

Jan 1, 1977

By Janos Foldesi, Calvin J. Konya

The determination of the number of primers necessary to efficiently initiate an explosive column charge is essential to good blasting. If the number of primer is insufficient, the total energy stored in the main charge will not be released. On the other hand, the use of too many primers will be counterproductive and raise the blasting cost. Tests were conducted by the authors to determine the correct priming procedure for a basalt quarry. This paper describes the results of those tests.

Jan 1, 1976

By Mike Koehler

An underground mine that produces aggregate limestone was in operation for approximately eight years when geological changes resulted in dangerous rock falls. The roof in the mine was not bolted; therefore, the drilling and blasting program was called upon to maintain roof integrity. Drilling and blasting were analyzed and modifications were adopted to stabilize the roof. Initial changes were made in the drilling equipment, drill pattern, explosive type, and timing. Any amendments made, after the initial phase, were made individually so it would be easy to discern which changes worked.

Jan 1, 2002

By Larry R. Fletcher, John W. Kopp

The safety record for explosives in U. S. mining is excellent considering that over 4 billion pounds of explosives are now being used each year. However, blasting accidents remain one of the most serious concerns based on the number of injuries, the injury severity rate and the disaster potential. The Bureau of Mines has been analyzing blasting accident data obtained from the Mine Health and Safety Administration (MSHA) to determine the most frequent causes of mine blasting accidents and to examine trends in blasting accidents. This accident analysis is an update of two previous blasting accident studies conducted by the Bureau and published in 1983 and 1987.

Jan 1, 1991

By N Vijay Mohan, K V. Balamukund, G Ananth Ramulu

Jointing of steel rods in reinforced concrete structures needs careful consideration as it renders the structure weak at the joint. The jointing is usually done at sections of structural members, where the bending moment and shear force are least. Jointing is done either by overlapping the rods or welding or by mechanical splicing. A novel method of jointing them is by inserting the two rods in a steel sleeve and cladding it on to the rods by subjecting the sleeve to explosive energy. A rod jointed in this fashion is tested for direct tension and bending when used in a reinforced concrete beam. The test results show that it is an effective method. The advantage is that a number of joints can be made in a single operation.

Jan 1, 1993

By Courtney Vallejo, Rafiqul Tarefder

This study examines the effects of small scale airblast experiments on cohesive soils and the resulting ground vibrations and crater geometries. Relationships for ground vibration attenuation with soil depth and distance from the blast source were developed. The study is part of a broader research topic of understanding the vulnerability of earthen embankment dams to blast loading. Many earthen embankment dams in the United States were constructed more than fifty years ago and were not designed to withstand high-stress loading such as blast loading. These structures may be susceptible to failure and it is important to describe the response of the earthen dam during a blast event.

Jan 1, 2013

By Janice Reed

The first seismograph was developed around 132 AD. Much has happened since then. The “modern” seismograph (> 1920) has seen a lot of changes. From falling pin seismographs to magnetic tape units to today’s Z-curve analysis models, the blasting seismograph remains a necessary and useful tool to the blasting community. But why so many changes? What forces drive the advancement of the seismograph? There are many answers and aspects to this question. Research, regulation, and technological advances are the primary forces behind innovation in our industry. But these three forces also drive each other. Research drove our industry from displacement seismographs to particle velocity seismographs. Technology took us from 80 pound seismographs to units weighing less than 5 pounds. Regulation (and litigation) - the driving forces behind the Z-curve analysis units. How have these innovations helped today’s blaster? Have there been any negatives? It is important for today’s blaster to understand how we got here and why.

Jan 1, 2005

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 Mario Karfakis, G. Langlois

Well stimulation is the process by which any production well, whether for production (extraction), storage (injection) or deep interaction (remediation, monitoring, etc) can be made or stimulated to flow at higher levels. This stimulation is driven by active methods to increase the permeability in the near-well environment and create a larger zone of communication between a well and the reservoir it services. Well stimulation is a crucial aspect of well completion and reservoir engineering and is a subject of careful pre-drilling planning. In many modern industrial endeavors the effectiveness of well stimulation is often critical to economic viability. Because of the broad impact of well engineering on several large industries (petroleum and natural gas extraction and storage, geothermal power, groundwater monitoring, extraction and management, environmental remediation, mining and minerals extraction, etc.) changes in the state of the art in well engineering and well stimulation can affect the capabilities of very diverse and disparate industries. This paper is an effort to communicate the status and effectiveness of current practice and technology in well stimulation. The intention being that effective communication of progress can spur innovation in industries that require well stimulation but are removed from immediate communication of technological or practical improvement.

Jan 1, 2009

By Mark S. Stagg, Steven V. Crum, Stephen A. Rholl

As part of its ongoing research concerning rock fragmentation by blasting, the Bureau of Mines has undertaken a series of test blasts where six cylinder-shaped pieces of granite rock were fragmented using high explosives. The tests were intended to: 1) Establish a dataset that could be used in the development and verification of theoretical models that simulate rock blasting and 2) To add to the fragmentation data currently being collected by Bureau researchers. The cylindrical geometry was chosen so that the fragmentation could be directly compared to two-dimensional computer simulations that assume an axisymmetric configuration as well as more sophisticated three-dimensional models. The granite cylinders, Carnelian granite and Charcoal granite, ranged in size from about 0.46 meters (18 inches) to 0.58 meters (23 inches) in diameter by 0.91 meters (36 inches) to 1.52 meters (60 inches) in length. Physical rock properties tests performed on the Charcoal granite cylinders indicated that the rocks did in fact have similar physical characteristics. PETN-based detonating cord and dynamite were used as the explosive charges and estimates of the values of some important physical properties are given. For the first five tests, the blasted rock was contained by a heavy rope mat suspended inside the Twin Cities Research Center's blasting shelter. The fragments from each of these shots were sorted and weighed to determine the corresponding fragment-size distributions. Even though different types of granite and cylinder sizes were used, similar fragment distributions were produced from shots that used a similar explosive, in this case the PETN-based detonating cord, and comparable burden-to-charge diameter ratios. Significantly coarser fragmentation was produced from a blast that used dynamite as the explosive charge. Fragment velocities were calculated using photographic data from the sixth test which was shot unrestrained in a quarry and filmed with high-speed cameras.

Jan 1, 1990

By Edward J. Jr Walter

This paper discusses the use of slant hole drilling and water matting as an effective method of reducing costs in shaft sinking operations through a general review of cost priorities for the contractor.

Jan 1, 1976

By Bharat B. Dhar, M D. Nabinllah, A J. Prakash

The study is an approach made in simulating air overpressures induced by surface blasting from those produced during gallery blasting in the laboratory, and experiments conducted on a portable window with a view to establish the sound pressure Level (SPL) for cracking of window glasspanes.

Jan 1, 1994

By S. P. Singh, Turgut Yalcin

The physical characteristics of blasted rock are fundamental variables affecting the economics of mining operations and are in fact the basis for evaluating the quality of a blast. A study was designed with the objective of quantifying the effect of muck size distribution on scooping operations in a mine.

Jan 1, 2002

By E Emery Jr Gray

A need for more delay periods other than those normally manufactured throughout the explosives industry rarely occurs. This paper will discuss one such incident from an analytical view through practical application.

Jan 1, 1976

By Erik K. Lauritzen, Jorgen Schneider, Niels Madsen

From 1986 to 1988 Kalaallit Tunisassiorfiat (KTU)/Gronlands Hjemmestyres Produktionsvirksomhed (the part of Greenland's own governing body which is in charge of production activities) has been responsible for blasting projects in the following 4 towns: Ilulissat/Jakobshavn, Qasigiannguit/ Christianshab, Qeqertarsuaq/Godhavn, Sisimiut/Holsteinsborg

Jan 1, 1989

By R J. Roach, D Roy

After months of discussion on ways and means to improve productivity in the shaft sinking process, it was decided to look at those areas where, historically, methods have been stagnant for many years. These categories included drilling, hole diameter, drill patterns, explosive types, explosive loads, initiation techniques, cut design, wall control, fragmentation and heated magazines.

Jan 1, 1997