Search Documents

By Fumihiko Sumiya, Kunihisa Katsuyama, Yuji Ogata, Yuji Wada, Yukio Katoh, Yoshikazu Hirosaki

In our previous work, the results of photographic observation using a high speed framing camera showed that the difference between precursor air shock wave velocity and detonation velocity was primary factor for the channel effect. It is assumed that the decreasing precursor air shock wave velocity can prevent the channel effect in charge hole.

Jan 1, 1996

By C. Adcock, R. Farnfield, G. Adderley

The use of explosives to create special effects in the film industry is a well-known past time. A recent production required simulation of a large scale water splash from the effect of a statue falling from a cliff edge and impacting on an open body of water. This was to be achieved through the use of precisely delayed explosions detonated near the surface of the water. A survey of the area revealed a breeding farm for sea bass approximately 250 metres (273 yards) from the intended blast area. It was initially thought that the water pressures produced for the detonation of the explosives may cause harm to the fish. Much work has been carried out over the past few decades on the effect of open water blasting and its effects on aquatic wildlife; this includes water pressure modelling techniques which can be used as predictive tools.

Jan 1, 2010

By Jeff Peterson, Alastair Grogan

During the winter of 2001/2002, a number of seismic exploration projects were carried out in the Mackenzie River Delta area of the Northwest Territories, in Canada. The purpose of the seismic projects was to identify potential drilling targets for subsequent drilling programs, using explosives as a seismic source. Recent changes to fisheries regulations meant that blasting under lakes, the Mackenzie River and offshore from the delta, was not allowed to induce water overpressures in excess of 100 kPa in these water bodies, and that a water overpressure monitoring program had to be conducted to confirm that this requirement was being met. This paper describes the water overpressure monitoring program on one of the exploration projects, presents the results of the monitoring, and discusses the challenges of carrying out this work in the middle of an arctic winter.

Jan 1, 2003

By Stuart Brashear, Lee Schettler

The effect of water on several ANFO/emulsion blend ratios are documented by both physical observations and analytical testing to demonstrate the effect even small quantities of water can have on water resistant blends.

Jan 1, 1996

By Edward Barrody

There are wide variations in the values of heats of explosion and detonation as reported in literature. These values are not “stand-alone” or sole properties of the explosives. Specifications of the conditions under which they were determined are necessary to characterize these values. This paper proposes that these values are dependent on their oxygen content and the surroundings their products “work against” upon expansion. Also, the heats of explosion and detonation values can have the same values, but different products, showing that the products can take “independent paths” but have the same values.

Jan 1, 2003

By Thomas M. Keevin, Gregory L. Hempen, David J. Schaeffer

In an attempt to reduce the potential for fish mortality during the explosive demolition of Locks and Dam 26, Mississippi River, the U.S. Army Corps of Engineers, St. Louis District explored the use of a bubble curtain to reduce the fish kill radius of underwater explosions. Bubble curtains are walls of bubbles rising from a bottom-resting bubbler manifold supplied with compressed air. Demolition engineers have long been aware of the attenuating properties of air bubbles in water. As such, air curtains have been routinely used to protect underwater structures from damage by underwater explosive shock waves. However, their use in protecting aquatic resources during full-scale explosive demolition projects was untested.

Jan 1, 1997

By Duan Baofu, Wang Xuguang, Song Jinquan

In this paper, the model of optimizing selection on preparation of Powdery Emulsion Explosives(PEE) is established by the Neural Net Theory(NNT). On the basis of some data in the study of PEE, the training, prediction and optimizing selection of the Neural Net (NN) model are finished by a compiling procedure. The results indicate that the model is helpful to the preparation of PEE and worthy to extend and apply broadly. KTYWORDS Neural Net Powdery Emulsion Explosives Preparation Optimizing Selection

Jan 1, 2003

By Douglas A. Anderson

The US Bureau of Mines, in RI 8507, has shown that blast vibrations at low frequency are more likely to cause damage and complaints than those at higher frequency. Since that publication in 1980, the Office of Surface Mining and many state and local regulatory authorities have incorporated frequency in their regulations for acceptable ground vibration from blasting. Even when frequency is not explicitly stated in regulations, it may become an issue in hearings or in court.

Jan 1, 1992

By P Bellairs

The Hamersley Province is located 1000km to the North of Perth the Capital City of Western Australia and is of major economic significance due to the mining of extensive deposits of Haematitic Iron Ore for both domestic and export use. A small but significant proportion of the waste associated with these deposits presents problems due to its ability to spontaneously combust and react with explosives resulting in premature detonations.

Jan 1, 1996

By Steve Kane

Lightning is a very real problem in the surface mining industry. Today, as adverse market conditions continue to influence the surface coal industry, it has become necessary that all functions of the surface mining process become as efficient as possible. High production with reduced manpower is the winning combination of staying competitive in the market place. We at AMAX Coal are committed to staying in the coal business, but we have always been committed to providing a safe work environment for our people and will continue to do so in the future. Approximately two years ago, our Midwest mines installed state of the art lightning detection and warning systems at our mines. This paper will cover its application at Delta Mine; the benefits and problems encountered, and the impact this system has had on Delta Mine.

Jan 1, 1992

By I. Petrovsky

Presence of the ground water, especially flowing water, causes limitations in the type of the explosives, which can be used for the blasting development in the open cats and quarries. This presents really big problem in Russia, because more than 70% of the blasting holes are wet and filled by flowing water. The waterproof explosives need to be used in these conditions, which increases the cost of the blasting development. So the search of the methods to remove the water from the blasting hole and to prevent direct contact of the explosive material with the water is important. It will give possibility to use nonwaterproof explosives (such as ANFO) and decrease the cost of the blasting development.

Jan 1, 2003

By Alan Jorgansen, Dave Hummer, Scott Scovira

Kennecott Energy's Colowyo Coal Mine is the largest open pit coal mine in Colorado and produces 5.5 MM tons per year. Colowyo uses the terrace mining method to recover up to seven seams of rolling coal ranging in thickness from 5 to 20 feet. Draglines are used to strip overburden ranging from 60 to 120 feet thick off two coal seams. These two seams are characterized by soft and fold fractured coal and in past practice cast blasting caused excessive coal damage. As a result, to ensure minimal coal damage and high coal recoveries, the overburden was excavated in two passes. The first pass removed the upper overburden to within 10 to 20 feet of the coal seam. The second pass removed the remaining overburden above the coal. Two-pass mining was effective in controlling coal damage, but also carried significant additional costs.

Jan 1, 2003

By James Rowland, Marcia Harris, Richard Mainiero

This paper reviews the potential hazards posed by the toxic fumes produced by detonating explosives in surface mining and construction operations. Blasting operations produce both toxic and nontoxic gaseous products; the toxic being mainly carbon monoxide (CO) and the oxides of nitrogen (NO x ). The quantity of toxic gases produced by an explosive is affected by formulation, confinement, age of the explosive, and contamination of the explosive with water or drill cuttings, among others. Techniques to protect workers and the public from the potential hazards of explosive-related toxic fumes are discussed.

Jan 1, 2007

By Greg Parker

"As the Explosives Industry continues to evolve and condense, those involved, such as Blasters,Contractors, Distributors and Consultants, continue to be challenged by both internal and externalforces. Increased pressure by government agencies, higher safety standards, new levels of technology and mandatory certification programs, are forcing us to expand our awareness and increase our levels of efficiency. These higher standards require increased awareness. Increased awareness requires better training programs and better supervision with emphasis on production and the employee. This means the desire to improve must be instilled from the top down. this paper will explore the current impediments to this goal and discuss the possible solutions for achieving greater safety awareness, increased production and higher levels of personal achievement. Through the use of audio/visual aids, I will attempt to show the discrepancies as well as the solutions."

Jan 1, 1999

By Jerald E. Harris

"Often taken for granted, drill accuracy plays a major role in the relative success or failure of a blast.Expensive technological advances in equipment capabilities, drilling tools, communications, explosives, and timing can quickly be nullified by poor drilling."

Jan 1, 1999

By Zvonimir Ester

The course of motorway tunnel under construction was set only 2 m away from the main motorway. The thickness of the tunnel overburden rock was 9 m. During the tunnel construction the traffic on the motorway was not supposed to be interrupted. The tunneling was carried out by NATM with classical drilling of blastholes and by blasting.

Jan 1, 1998

By Kenneth Eltschlager

Blasting represents the highest risk of any surface coal mining activity that could result in injury and/or property damage off the permit area. In addition, blasting related issues e.g. flyrock, vibrations, air blast, etc., are responsible for a large percentage of citizen complaints. Thorough and consistent regulation of individuals certified to conduct blasting by the Office of Surface Mining Reclamation and Enforcement in Federal Program states and on Indian Lands under Federal jurisdiction is vital, as it serves to: facilitate coal production to meet the nation’s energy needs; protect people and property on and adjacent to Federal mining permits; form a basis for states to grant reciprocity certificates to Federal blasters; and be a positive example to primacy states. OSM issues Federal blaster certificates for blasting on Federal surface coal mine permits. The certification program includes experience, training and testing components similar to many of the states. But where a state program may focus on the specific blasting applications within its boundary, the OSM certificate requires a very diverse test to cover all potential blasting applications and products across the nation. Therefore, the Federal certificate is a good surface mining credential for blasters anywhere in the United States.

Jan 1, 2010

By Tapan Goswami

The main objective of the blasting phase in a coal mining operation is to maximise the coal recovery. However, coal loss due to blasting is a serious problem. The Australian Coal Association Research Programme (ACARP) reported in 2011 that in Australia one in every ten coal mines is completely wasted due to such losses. Coal is either lost in the spoil, largely due to the blasting operation or becomes diluted and cannot be recovered entirely. The major coal loss mechanisms include losses from the coal seam roof, the floor, the front edge and from dilution. Coal damage and loss mechanisms during cast blasting that have been observed by various authors include: •Excessive cast dragging the coal edge in the cast direction. Movements of this nature are oftenassociated with the formation of trenches. •Spatial movement of overburden where rock shears and moves in a plane above the coal seam,which damages and dilutes the coal. •Rock falling over the coal during the blast often producing indentations in the exposed coal. •The inappropriate use of bulk and initiating explosives that often results in coal damage. •Insufficient stand-off distances from the coal. The Australian coal mining industry has gone a long way towards addressing the coal loss issues since 2011: almost all operations now deploy touch-coal drilling and sporadically use gamma logging for loading overburden. A study was conducted to compare the effectiveness of touch-coal information in which some touch-coal blastholes were drilled on a fixed or random pattern. In another study, some blastholes were drilled to the touch-coal, gamma-logged and mapped to determine stand-off distances. It was found that the coal roof surface created by gamma-logged holes was the most effective option for minimising coal loss. As a result, a variable stand-off distance was found to be the key to minimising losses. This paper discusses the importance of coal mapping, the rock properties of the roof and floor interface of the coal seam, and the significance of loading and initiating designs in minimising coal damage. Furthermore, the importance of using electronic initiators cannot be emphasised enough. This paper also discusses how a cast blast can be initiated from many locations by mitigating geological abnormalities and thereby avoiding spatial movement of rock shearing in a plane above the coal seam.

By Khushaal Popli, Vanessa Roeland, Brian Hall, Carl Diederichs

Highland Valley Copper (HVC) has embraced an integrated Mine to Mill approach to comminution since the late 1990s. Previous blasting optimization was carried out through adjustments to blast pattern geometry (i.e., reduction of burden and spacing). This approach proved very effective and HVC reduced the burden and spacing of high energy ore blast patterns to what was considered the practical limit that still allowed for efficient drilling and bulk truck loading operations. While mining in the bottom of the Valley pit near the end of the previous pushback, HVC encountered high static groundwater conditions which enabled the transmission of elevated inter-blasthole pressures that had the potential to exceed safe operating limits for initiation products. This risk was mitigated through an expansion of burden and spacing for the high energy ore patterns, reducing the application of blasting energy and increasing the average particle size in Mill feed.

Feb 6, 2023

By Robert Boehnke, Bernd Mueller

This contribution presents an innovative, statistically supported method to predict blast vibrations in rock mass. For modelling the processes during and after detonation, a theory is employed which is based on linear momentum (so-called momentum theory), strongly supported by new measurement methods. During the course of the investigations, the following parameters have been found to dominantly influence vibrations: ! charge WB, includes geometrical factors such as borehole length and diameter (kg) ! detonation velocity cd of the explosives used (m/s) ! distance r between the points of emission and immission (m) and the statistically determined negative exponent n ! factor RM or RS of the rock mass which is related to the specific blast momentum and the drilling and blasting technique used and is statistically determined together with the exponent m (mm/kg or mms/kgm)

Jan 1, 2004