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By S. Nakamura, H. Taniguchi, K. Noguchi, H. Sugihara, T. Matsuzawa

It has been reported that expanded poIystyrene and ANFO prills ‘were mixed on a blasting site for controlled blasting (ISANOL). Although there seems to be few possibility of their segregation because mixing on a blasting site is done, there is a great possibility of segregation in packing, transportation and loading of the product due to the different densities of the two ingredients in Japan where mixing on a blasting site still remains inoperative. The fiee-flowing property of ANFO prills was lost with the passage of time because the Abel oil infiltrated into the expanded polystyrene and that gave the product high viscosity.

Jan 1, 2001

By Richard H. Granhom

Detonation pressure, or Chapman-Jouguet pressure, is an intrinsic property of an explosive, and like detonation velocity, is an indicator of explosive performance. Pressure and velocity are also important for calibrating computer codes and for other calculations such as the stress imparted to rock or metal by an explosive. The detonation pressures, P~cj, of many "ideal" explosives have been measured indirectly by recording some hydrodynamic flow variable other than pressure, with P~cj being inferred from hydrodynamics and the assumed Chapman-Jouguet equations. One such method is the difficult and expensive "aquarium technique''.] Commercial explosive manufacturers generally rely on estimates of P~cj generated by computer codes not explicitly designed for non-ideal explosives typically used in commercial applications. Over the last decade, U.S. national and government laboratories have developed in-situ gauge techniques such as the manganin gauge, for direct measurement of detonation pressure. Manganin is an alloy of copper, manganese and nickel, and is ideally suited for use as a pressure transducer because its electrical resistance changes with pressure, but is nearly constant with changes in temperature. A simplified manganin gauge technique adapted for use at a commercial test site is described and some initial results from measurements on commercial emulsion explosives are presented.

Jan 1, 1991

By Guillermo Silva

A novel, ultra-low density explosive composition, particularly suited for wall control and other applications requiring customising of the explosive’s energy output, has been developed. Being reactive in nature, the low density explosive enables the controlled dilution of dry blasting agents from their nominal densities down to values slightly less than 0.10 g/cm3. The product has been detonated at densities of 0.07 g/cm3 in diameters as small as 50mm under confined conditions, using a 227 g (l/2 lb.) primer. Recorded velocities of detonation ranged between 1200 m/set and 2200 m/set for densities between 0.07 and 0.2 g/cm3. Theoretical velocities ranged from 1700 m/s to 2500 m/s for the same density range. The low density explosive was insensitive to initiation by a blasting cap which is a desirable feature for transportation purposes. Mixing of the product with ANFO has been accomplished with minimum segregation making it suitable for applications where reduction of pressures are necessary.

Jan 1, 2000

By W C. Burkle

A rather common observation over the last several decades at least has been that rock or ore properties influence blasting results more than does the explosive type that has been used in the blast. It we accept that premise than it is held here that the material to be blasted should receive even closer attention as to its properties. Several years ago, Dr. Richard Ash published papers that pointed out the rock properties that mostly influence blasting. These principles are given attention in this paper. We have gone somewhat further - or lets say expanded this subject in regard to the role of rock structure in open pit blasting. Though open pit work is given some prominence, we believe that much can be observed and applied to underground mining.

Jan 1, 1979

By Rahim G. Haghighi, Calvin J. Konya

Fragmentation is the fundamental concern of rock blasting and it measures the effectiveness of blasting. Fragmentation is sensitive to not only the interrelationship among the design variables, but also is sensitive to local geology. Local geologic conditions have a significant impact on the success of a blasting operation.

Jan 1, 1986

By T Guiliani, F Ottuonye

Explosives casting is gaining increasing popularity as an overburden removal method in strip mining because the coats of using explosives to cast a percentage of the overburden to the spoil are lower than the costs of using stripping shovels or draglines to do all the overburden removal. This is due to the rising capital and operating costs of draglines and shovels.

Jan 1, 1989

By D E. Siskind

The Bureau of Mines performed a comparative study of nine sites at eight surface coal mines to determine if the presence of near-surfaced underground abandoned workings resulted in the generation of adverse long-duration, low-frequency blast vibrations. Six of the nine sites had underlying workings, and two had thick layers of low-velocity unconsolidated surface material.

Jan 1, 1990

By Dwayne Tannant, Jeffrey Loeb

Blasting techniques and protective measures exist that can mitigate risks associated with flyrock and the nuisance of vibration, and overpressure. However, these are often misused or not used because there are no prescriptive regulatory requirements and typically urban blasting guidelines do not exist. The relationship between the increasingly negative publicity that the urban blasting industry receives and the existing state of regulatory control on blasting in urban environments is presented.

Jan 1, 2012

By Gary B. Hemphill

Each year the demand for precision blasting increases due to the reduction in the amount of prime land. More site preparation and hone building requires blasting than they did a decade ago, Because of this increased need for blasting in more populated areas, the need for blasters and engineers knowledgeable in work involving blasting nets has increased.

Jan 1, 1978

By R. Franfield, W. J. Birch, L. Bermingham

Previous researchers have put forward two different theories as to the origin of air overpressure from quarry blasting. In 1980, Siskind et al postulated that the initial face movement gave rise to the displacement of air and that this resulted in the air overpressure pulse. However in 1990 McKenzie et al carried out research that indicated that the air overpressure pulse came into being as consequence of the shock wave created by the detention of the explosive charge in a blast hole, rapidly propagating through the rock and then impacting on the quarry face.

Jan 1, 2013

There is an intuitive tendency to equate rock strength with rock stability, yet the two must be evaluated separately. A slope in strong hard rock is not necessarily stable, nor is a slope in weathered weak rock necessarily unstable. In some cases the reverse is true, depending on the geometry of joints and weak planes. The time element is a matter of special concern, that is how suddenly the failure begins and how rapidly it progresses. Sudden failures can be catastrophic, whereas creep usually is not. In soils and weathered rock, the process is usually incremental and is more likely to give some warning of impending failure. With careful observation, the failure process in these materials can be detected and monitored instrumentally or visually. In some cases, the slope may be stabilized, reinforced or modified. When that is not possible, there is usually enough time on this type of slope to remove men and equipment from the area before complete failure occurs.

Jan 1, 1996

By Salah A. Taqieddin

The blast casting technique of removing overburden is an innovative technique which was successfully used in the mining of certain surface coal and quarries. This method was found to be efficient in minimizing the labor and equipment cost while accelerating mining operation with safety. This method was successfully applied to horizontal as well as to dipping coal seams. Also it was practically applied to single as well as to multiple ore bodies

Jan 1, 1992

By D. Johansson, C. San Miguel, U. Stenman, N. Petropoulos

Blasting is a commonly utilized method in civil engineering projects and mining operations. Ammonium nitrate-based (AN-based) explosives are the most efficient explosives today in terms of handling and performance. However, a side effect is the production of gases. The reduction of these gases plays an important role in the safety and environmental aspects in the working place. Therefore, optimizing the recipes of explosives is vital for minimizing the environmental impact and increasing performance. The aim of the project is to provide results and recommendations on the use of emulsion commercial explosives to support the Swedish mining industry and tunnel-contractors as well as the explosives manufactures. The approach was to test various recipes of civil emulsion explosives to investigate the generation of toxic fumes (CO, CO2, NO, NO2 and NOx) during their detonation. To further increase the knowledge of the influence of different additives, ammonium nitrate prills were added in various percentages. The experimental configuration consisted of magnetite mortar cylindrical specimens with a 50 mm borehole at their center, filled with emulsion explosive. Several tests with different emulsion compositions regarding ammonium nitrate additives (10%, 20%, 25%, 30% and 35%) were carried out in a blasting chamber. The measurement equipment was composed of a flue gas analyzer. The instrument was meticulously cleaned after every test, as well as before and during the tests due to condensation (high humidity and dust) at the inlet of the instrument. The emulsion was manually sensitized with microballons and pumped into the cylinders to ensure lack of bubbles, which could introduce inhomogeneities. The acquired gas concentration data was complemented with temperature, humidity, and VoD measurements. The results showed a linear increase of nitrogen gases as the percentage of ammonium nitrate prills increased. On the other hand, carbon gases had a relatively low coefficient of determination. The VoD data showed a behavior that can be described with a simple quadratic equation.

Jan 1, 2024

By Masanobu Morita, Koichi Kurokana, Kenji Hashimoto, Yoji Tasaki, Yukio Iida

"It has been the long desire of blasting engineer to realize the automatization of tunnelblasting to improve the safety and efficiency. As for bore hole drilling, the automatizationhas been achieved by the improvement of drilling machine. However, the firing process isstill depending on the hand-operation. We developed the wireless initiating system using amacrowave power as a step for automatization of tunnel blasting operation. In this paper,we present the outline of the wireless initiating system and the results of experimentalstudy of the wireless detonator which is key component of the system."

Jan 1, 1993

By D P. Onag, B Mohanty

AECL Research (AECL) has constructed an Underground Research Laboratory (URL) as a facility for research and development in the Canadian Nuclear Fuel Waste Management Program. The objectives of the program are to develop and evaluate the technology to ensure safe, permanent disposal of Canada's nuclear fuel waste. Several multidisciplinary experiments and engineering demonstrations are planned for the URL over the next ten years.

Jan 1, 1991

By Richard W. Watson, Julius Roth

The Bureau of Mines has recently completed a contract study of the hazards associated with surface mining.! Part of this effort involved an analysis of surface mining accidents associated with blasting activities. For this purpose, 71 reports of accidents investigated by the Bureau of Mines or the Mining Enforcement and Safety Administration (MESA), covering the period from 1962 to 1976, were collected and analyzed. In addition, blasting accident frequencies for the period 1973-1976 were extracted from the central computer files maintained by the Health and Safety Analysis Center (HSAC) in Denver, Colorado. This paper presents a preview of the findings, which are treated in more detail in the final report.

Jan 1, 1978

By Jeff Friedman

This paper addresses certain problems to be encountered when a blasting contractor agrees to provide indemnification. Nearly 100% of all blasting work is performed pursuant to a contractual agreement. Whether the explosives engineering firm works directly for the property owner, or for a general contractor by way of subcontract, indemnification agreements are generally required to protect owners, operators, general contractors, and other interested parties in the event there is subsequent litigation. These contractual requirements are typically referred to as indemnification and “additional insured” agreements. We will address the ramifications of contractual indemnification as well as “additional insured” agreements in this presentation. Some of the aspects of this paper will include:

Jan 1, 2004

By Z X. Zhang

In sublevel caving mines, eyebrow break usually gives rise to lower ore recovery and worse safety in the field. Eyebrow break is caused mainly by two tensile stress waves: one from the front surface of a blasting ring, and the other from the roof of the drift. In order to reduce the two waves and finally to reduce eyebrow break at Malmberget mine, we employed two methods: (1) cartridge charge, and (2) double-primers in each blasthole. The two methods were tested in one ore body called ViRi. A total of 10 rings with the cartridge charge and 25 rings with the double-primers were blasted. At the same time a total of 34 ordinary rings were blasted in the same ore body. The result shows that the eyebrow break is 3.0 m for the ordinary rings, 2.3 m for the cartridge charge rings, and 2.1 m for the double-primer rings, respectively. In addition, the ore recovery for the double-primer rings is increased by 3% on the level of ViRi930, compared with that for the ordinary rings.

Jan 1, 2011

By Alfred Osborne

Progressive cavity type pumps are widely used by commercial explosive manufacturers for pumping water gel, emulsion and emulsion / ANFO blend explosives. Tests by explosives companies and investigations into incidents have shown that this type of pump can develop dangerously high temperatures when operated deadheaded or dry. [i.e. with no flow of product through the pump.] In some tests and incidents, explosion or detonation of the explosive (or residual explosive) in the pump has resulted.

Jan 1, 2002

By R C. Berglund

Since the Republic Mine began production in the mid 1950's, drilling and blasting practices have continually changed. In recent years, progress has been achieved through the development of more precise blast engineering methods, in greatly increasing the use of non-water resistant ammonium nitrate explosives, and in changing to a non-electric in-hole delay initiation system. Also, recent experience indicates that ammonium nitrate fueled with nitropropane and methanol is a viable substitute for aluminized AN-FO.

Jan 1, 1980