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By Alastair Torrance

The performance of commercial explosives is clearly influenced by the conditions under which they are used. Mining companies are supplied with Technical Data Sheets which provide details about explosive properties and its suitable application. These are generally produced using laboratory techniques which may not accurately reflect the quality and performance of the product in the field.

Jan 1, 2013

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 Paul Worsey, Randall Franklin

This paper is based on an undergraduate research project undertaken for the explosives emphasis in the UMR mining engineering degree program by the first author. The purpose of the selected research topic was to investigate the impact sensitivity of commercial detonators to determine their relative safety for handling and how much abuse they can take without accidentally firing. A modified BAM tester was used for the investigation. Both electric and non electric detonators were impacted at incremental positions along their length to determine the relative effect of their various components. Repeat impact tests were also conducted to see how a damaged cap would react to repeated abuse. The results indicate that it takes a significant amount of impact energy to initiate commercial detonators. They also indicate that repeated abuse can increase sensitivity. Modern commercial detonators appear to be relatively insensitive to impact (an order of magnitude above RDX in the standard BAM test) and this is mainly due to their construction. This explains why damaged caps with exposed powder are more sensitive. Their measured insensitivity correlates with rough handling not being a major cause of blasting accidents.

Jan 1, 2004

By Gungor Tuncer, Ali Kahriman, Abdulkadir Karadogan, Savas Gorgun

The principal disturbances created by blasting in open pit mines are vibrations, air blast and fly rock. All of them, under some circumstances, caused damage to structures nearby and apart from this can be the source of permanent conflict with the inhabitations who live close to the operation. Therefore, prediction of ground vibration components is of great importance for the minimisation of the environmental complaints. This paper presents the result of ground vibration measurements induced by bench blasting realised at Can Open Pit Coal Mine located close to the residential area of Can town. Within the scope of this study, in order to predict peak particle velocity and determine the slope of the attenuation curve for this site, ground vibration components were measured for blast events during bench blast optimisation studies over a long period. During the study, while the parameters of scaled distance were recorded carefully, the ground vibration components were measured by means of two different types vibration monitors (White Mini-Seis and Instantel Minimate Plus Model) for 54 blast events. At the end of evaluation an empirical relationship with reasonable correlation was established between peak particle velocity and scaled distance for this site.

Jan 1, 2001

By Qi Jinduo, Gong Min

On the basis of actual parameter of wall control blast in Nanfeng mine, China, the process of dynamic stress changing between two column charges was studied recently for a presplit-cushion blast by holographic photoelasticity. In the experimental model, two holes were simultaneously detonated from both ends (four ignition points). The bottom of the holes were loaded more than other parts (heavy charge). Under these conditions, four consecutive isochromatic fringe patterns at different times were acquired in one loading run, and the characteristics of the stress distributions were compared at different places and times in the holes. It was found that interaction types of stress waves vary along the holes. The theory is posed that the stress wave which is formed by the interaction of earlier producing P wave and later S wave along a distributed line charge is the most important part in all stress waves. Research indicates that a heavy charge in the bottom of the holes is crucial to producing a presplit-cushion effect at the bottom. "End Effect" doesn't affect the magnitude of stress along linking lines between the bottoms. The chief fields of the "End Effect" are also explained in the paper.

Jan 1, 1998

By Michael S. Wieland

Toxic fume concentrations from industrial mining explosives depend somewhat upon the type of rock (or other strata) confinement. Though traditional detonation theory disregards this influence, the work principal from thermodynamics reveals it, when the violent interactions that transpire within the rock blast are taken into proper account. Resolution of the work principle technique requires total thermodynamic equilibrium under constraint, so the nonequilibrium dynamics is rendered in that way, using an old trick from theoretical mechanics that revises the representation of forces. The rock pressure reduces to a four-component sum: the rock compressive strength and natural atmospheric pressure, as reckoned quasi-statically, and the gravitational influence and reversed inertial resistance, as reckoned dynamically. Tabulated specie concentrations and graphical trends reveal the dependency upon rock pressure, rock temperature and the fuel-oil percentage in ammonium nitrate mixtures (ANFO), used to illustrate the model. Rigid-wall test chambers have notable ullage (residual space), where rapid expansion influences the reaction quenching, yielding a fume spectrum unlike that for rock confinement; reported rock tests are therefore used for comparisons. For the thermodynamic regime where quenching occurs, seven concentrations are resolved, including carbon monoxide (CO) and total nitrogen oxides (NOX). Their trends yield inferences regarding the way unwanted charge desensitization from transitory hole-to-hole wave impact in conjunction with reduced rock pressure can yield nasty toxic fumes, the dark rusty cloud phenomenon!

Jan 1, 2005

By Joseph L. Uraco, Harry C. Verakis

The use of explosives in underground coal mines presents a potential risk for serious injuries and death to miners. Widespread disasters have occurred from the explosion of methane and/or coal dust initiated by blasting with explosives. Many of these disasters took place in the early 1900's when the use of black powder for blasting was prevalent. Historically, the investigations in the U.S.A. to develop and test safer explosives for blasting coal began in 1908 when a testing station was established in Pittsburgh, Pennsylvania. Since that time, great strides have been taken in the development of safer explosives. The use of safer explosives has significantly reduced blasting accidents in coal mines. Enactment of legislation, such as the Federal Coal Mine Health and Safety Act of 1969 and enforcement of regulations has also improved blasting safety. More recently, MSHA began a major revision of its regulations for blasting in coal mines. In 1988, MSHA published final rules for the approval and use of permissible explosives in coal mines. The approval requirements for explosives address testing and evaluation. The requirements include tests for sheathed explosives which represent a new technology. The use regulations provide increased safety protection for miners by including standards to address identified hazards. Major aspects of these standards, such as qualifications for blasters, multiple-shot blasting and the use of sheathed explosives are discussed.

Jan 1, 1992

Computational techniques in determining particle size distributions after blasting is getting wide acceptance. A well known approach to extract this kind of information from digital images is edge detection. The number of edge points on a given image increase proportional to the increase of the particles on the image. By selecting a conveniently smooth threshold, counting the signed edge pixels may be a suitable metric further used to quantify the number of particles in the image. Here we propose an image processing algorithm together with Adaptive Neuro Fuzzy Inference System (ANFIS) to efficiently count the rock particles with various sizes on a given surface. To determine a suitable approximation for a mapping between the number of edge pixels and the number of particles, ANFIS is a suitable tool. As a trainable classifier ANFIS proved itself as being better efficient approach than other well known multilayer perceptron classifiers. ANFIS is trained by using convenient training data pairs previously experienced from empirically counted sample images. When given a new image containing the particle information of selected surface, the hybrid neuro fuzzy image processing approach provides satisfying performance on counting the correct number of particles up to the given scale of sizes. In this paper an experimantal study for assessment of particle size using ANFIS is presented.

Jan 1, 2004

By Seung-Kyu Baek, Chang-Ha Ryu, Yang-Kyun Kim

Safety concern is one of the most important parameters in the design of building demolition by explosive blasting. Accidents were sometimes reported due to the flying chips of fragmented materials in building demolition work in urban area. Laboratory experiments were performed to investigate the failure behavior of reinforced concrete pillars under blast loading and to develop an effective protection technique. Sixteen reinforced concrete pillars were constructed with two sizes: 450×450×1800 mm and 600×300×1800 mm. The failure behavior and the flying chip velocities were observed by means of a high-speed camera. Protection scheme was designed and the effects of several protection materials were investigated. Two kinds of non-woven fabrics and wire net were tested as protection materials. The results showed that reinforcing bar was one of the important factors to determine specific charges, and that mesh size of wire net and tied-up method affected the protection of flying chips. Control of gas effects is also a key to the control of flying chips. It was recommended to use both wire net and nonwoven fabrics as primary and secondary protection materials. Such protection scheme was successfully applied to the explosive demolition of 16 and 17-story apartment buildings.

Jan 1, 2002

By Pharis E. Williams

The ability of voids, microballoons, and even solids to sensitize explosives has been known and used for many years. This phenomenon has generally been studied and reported under the terminology of "hot spots" because of the increase in local pressure and temperature when a shock wave encounters such sensitizers. A method for treating this phenomenon in detonation theory or in a detonation model has been studied for almost the same length of time. Perhaps because of the complexity and non-linearity of the void, or microballoon collapse, several of these studies have used the expediency of including additional terms in the burn rate law to account for the influence of hot spots. The detonation model proposed here considers the sensitization due to discontinuities in the shock impedance to be a mechanical phenomenon to be accounted for in the mechanical equations governing the detonation and not in the burn rate law. While this is not a new contention, the method for handling this non-linear phenomenon within the proposed model is new. The model also includes a method which accounts for the manufacturing variables of emulsion matrix cell size, microballoon size and type, as well as energetic additives.

Jan 1, 1992

By Sergio Segovia Parra, Victor Hernan Sheen Uriol

This contribution of the concept of mass blasting both closing and production allows breaking paradigms, to limit the number of tons to thunder. The areas of geotechnical different mining large mining companies worldwide and especially from the National Copper Corporation (CODELCO, Chile) has been declining volumes closing blasting and production, with the misconception to protect the end walls of the pit, before any geotechnical risks caused by various types of faults; especially the circular faults. A blasting of small tonnage can do more damage to a wall when it is not properly sequenced, leading to the coupling of the wave train and therefore the exponential damage in/s (peak particle velocity, PPV) on the wall of the Tagus. Blasting closing mass production and contribute technically and operationally in the dynamics of the following operations: loading, hauling, crushing, processing and preparation of the final product; eliminating delays to return to thunder small volumes where one must stop all mine equipment, incurring high costs and especially losing valuable time in the continuity of the following unit activities.

Jan 1, 2015

By Anders Lagerkvist, Agne Rustan, Tommy Edeskar

Landfills containing house hold waste produces methane gas during its decomposition. This gas can be recovered and used for heating purposes or as fuel for vehicles. Gas drainage pipes are installed in the landfill and connected to a central suction point. Methane gas is produced over several years until the slots in the drainage pipes are clogged by black mud. And the bottom of the vertical drainage pipe are filled with mud and water. The hypothesis tested in this paper is if blasting in the drainage pipes could activate the production and flow of methane. In the first part of the paper we have studied what maximum linear charge concentration could be used in different size of PE-pipes place vertical on surface and surrounded by air. The results show that the maximum linear charge concentration for single blasts varied between 5-10 g/m, depending on the diameter of the pipe (90, 100 and 160 mm). Maximum charge concentration for the repeated blast varied between 2-5 g/m. In the second part of the paper we study what maximum linear charge concentration could be used in situ for full scale blasting tests in a special prepared test area which later on was dug out after the blastings. Up to 40 g/m could be used without damaging the top of the 160 mm diameter pipes. The increase in methane flow was so low so it could not be measured c4.5 m3/h. The conclusion therefore is that the stimulation of methane flow by explosives is not enough.

Jan 1, 2000

By James H. Redyke

In August, 1980, while finishing construction of the new stack, one of the flues mysteriously collapsed, killing three people and injuring several others. Several months later a British international steeple-jack company was hired to demolish the remaining portion and make a detailed inspection of the balance of the chimney. During this contract almost one hundred core samples were taken from all parts of the structure including the 32-inch thick base. As the result of these tests and the investigation, the Power Company decided to demolish the complete structure. Because of the critical time element, the decision was made to use explosives in the removal of the structure. To give you some perspective as to the size and dimension of the stack, it was 900 feet tall, 80 feet in diameter at the base, and 70 feet in diameter at the top. The two remaining flues were 25 feet in diameter and extended 30 feet beyond the top slab of the chimney. The outside of the structure was referred to as a wind shield. The lower 120 feet were 32 inches thick and the remaining 780 feet were 12 inches thick. The decision was made to prepare and shoot the chimney at the 120-foot elevation because the debris from the collapsed flue was confined in the base section and could not be easily removed. After extensive and costly engineering, we determined it was necessary to construct steel columns to bear on the lower 120-foot section, which would act as a hinge and guide during the dropping of the structure.

Jan 1, 1982

By Lewis L. Oriard

Ground vibrations associated with blasting are generally in a higher frequency range and of shorter duration than those generated by earthquakes, and the intensity scales for earthquakes cannot be applied directly to blasting vibrations without modification. Further, the profession does not need an intensity scale merely to estimate vibration intensity. If the blasting in question was not monitored instrumentally, it is a simple matter to estimate the range of intensities based on published prediction formulae or data from various sources such as Oriard (1), Nicholls et al (2), Hendron and Oriard (3), Siskind et al (4), and others. However, the profession has a serious need, for purposes of evaluating damage claims, to understand the relationships between vibration intensities and the levels of observed effects. The criteria for threshold damage do not apply to typical cases which usually involve structural damage. If the damage in question would have required ground vibration with a particle velocity of, say, 20-120 ips, damage is not verified by showing that the vibration merely approached a suggested limit to avoid threshold damage. That is not the question. This paper provides some guidelines for comparing severity of damage to intensity of vibration which would be required to cause such damage, much as is done when determining earthquake intensities. In addition, this paper includes a discussion of strain amplitudes induced by environmental forces, the predominant causes of damage to structures. Also, certain popular myths regarding blasting damage are discussed in the paper. Due to space limitations, the paper will not include a discussion of airblast effects.

Jan 1, 1989

By Joshua Micah Hoffman, Catherine E. Johnson

The recruitment and retention of future talent into the explosives industry is becoming increasingly important. One potential area from which future talent can be recruited is local student chapters. Many of the student chapters are closely connected with engineering programs. While this makes sense and both entities benefit from these arrangements, there is a trend of job placement primarily in the engineering industry. Before the explosives industry can begin to compete with other industries, it should be determined what is drawing the students into these other fields. The work presented in this paper sought to better understand the collegiate student population from which a portion of future explosives professionals will emerge. This was done through the use of an anonymous online survey distributed to the student members of the International Society of Explosives Engineers, as well as, members of SEE student chapters. The survey contained questions about future job and career plans, ideal job placement, and expectations of salary. The purpose of the survey was to determine what these students expect or require from a career in the explosives industry. This information can help steer recruitment activities and job offers. Through understanding what is incentivizing these students who have accepted or plan to accept jobs in other industries the explosives industry can better posture itself to be more competitive in recruiting from the collegiate talent pool.

Jan 1, 2014

By Joshua Hoffman, Catherine Johnson, Braden Lusk

Blasting conducted in surface coal mining operations in the Appalachian region consumes a significant amount of blasting agents. Emission of oxides of nitrogen (NOx) from these operations potentially represents an environmental challenge. This paper presents work conducted to quantify NOx output from the detonation of blasting agents common to surface blasting operations in surface coal mines. Annual ANFO and emulsion consumption data was collected from an operational surface coal mine located in West Virginia. It is known that many factors contribute to the types of gaseous byproducts released from the detonation of explosives. These factors include but are not limited to: fuel to oxygenator ratio, degree of confinement, and contamination. While, past research has been conducted to study the relationships these factors play on the release of NOx, these findings do not agree with one another. The annual explosive consumption values from the West Virginian mine were applied to NOx emission conversion factors in published literature. This lead to a range of NOx emissions from 95 to 914 tons in a year. Given the wide range of NOx production the utility of this information is suspect. The EPA recognizes a standard factor of 17 lbs (NOx)/ton (ANFO) however this factor is based on chemical composition and does not address contamination, confinement, or AN to FO ratio. This factor when applied to the West Virginia Mine's explosive consumption produced a value of 215 tons of NOx. There is a lack of information on NOx emission from emulsion type explosives. The work presented in this paper can be used by blasting professionals to quantify NOx emissions and guide future work for producing better predictor factors.

Jan 1, 2014

By James Ludwiczak

This paper consists of the conduct of a forensic criminal investigation of the components, construction, use, and functioning of two suicide bombs. As the title states, the task was to form professional opinions as to whether the bombs would work, would cause property damage, and would injure or kill. The bombs were created and installed by a defendant in a Federal death penalty case where the defendant’s daughter was killed in a shootout with the West Virginia State Police. The two black powder bombs were placed under the front seats of the defendant’s automobile and were designed to function by the use of a toggle switch connected to the automobile’s cigarette lighter. The forensic work first consisted of an inspection of the remains of the wiring system and bombs at the Bureau of Alcohol, Tobacco, and Firearms Laboratory, in Ammendale, MD. This was necessary to determine and detail the wire diameter and lengths, the lengths and size of the wire used, the type of toggle switch used, the type of containers, the type of rocket motors used to initiate the black powder, the manufacturer and amount of black powder used in each bomb, and the type, wraps, and amount of duct tape used for the construction of each bomb. Using this data, tests were conducted by duplicating the wiring system and the two bombs to insure that the system functioned properly. Each bomb was duplicated and initiated to observe the violence produced when initiated in the open air. Duplicate bombs were placed under the seats of a similar type of automobile and initiated. The purposes of the tests were to duplicate the bombs, to observe the violence of the initiation, and to observe the damages to the automobile produced by the initiation.

Jan 1, 2007

By Gungor Tuncer, Ali Kahriman, A. Kadir Karadogan, Savas Gorgun

The environmental problems arisen from ground vibration and air blast have been faced and discussed frequently in various industries such as mining, construction, quarry, pipe line etc. where blasting is unavoidable operation. Structural damage due to ground vibrations creates great socio-economic problems for mine and quarry management as well as for the people residing in its vicinity, therefore in bench blast design, not only the technical and economical aspects, such as block size, uniformity and cost, but also the elimination of environmental problems resulting from ground vibration and air blast should be taken into consideration. With the general trend towards larger blasts in mining and infrastructure excavation, ground vibration and air blast problems and complaints have significantly increased. With increasing environmental constraints on the levels of disturbance induced by blasting operations upon nearby residents, there is an increasing need to be able to design cautious blasting with greater precision, therefore determination of maximum amount of explosive per delay for a certain distance especially in large blasts is of great importance for the elimination of these environmental problems. In another word, prediction of ground vibration components is extremely important for the minimisation of the environmental complaints. Estimating of particle velocity and other components of ground vibration with reliable approaches will give important facilities to the blasters. Although many studies had been carried out to isolate environmental problems induced by blasting in the past, a general reliable formulae has not been established yet. Due to restrictions on the complexity of ground motion, blasting and test site factors, experimental studies are still necessary for each site to minimise environmental issues. This paper presents the results of ground vibration measurements carried out during the excavation activity for contruction of an organised industrial region located nearby Istanbul in Turkey. The major rock type is granite that is encountered at this site. Within the scope of this study, in order to predict peak particle velocity level and produce a site-specific propagation curve for this site, ground vibration components were measured for blast events during bench blast optimization studies over a long period. In blasting operations; ANFO (blasting agent), gelatine dynamite (priming) and delay detonators (firing) were used as explosives. While the parameters of scaled distance (charge quantity per delay and the distance between the shot and the station) were recorded carefully, the ground vibration components were measured by means of two different vibration monitors for every event. Then, the data pairs of scaled distance and particle velocity were analyzed. The equation of scaled distance extensively used in the literature was taken into consideration for the prediction of peak particle velocity. At the end of statical analysis and evaluations an empirical relationship with good correlation was established between peak particle velocity and scale distance for this site.

Jan 1, 2000

By Andre Koekemoer, Gys Landman

At the moment, electronic initiation is migrating from a position of a specialist niche to that of a more widely applied technology. Ease of use and deployment rate are becoming aspects of greater concern for end users.

Jan 1, 2011

By M. Gebhardt, J. Johnson, S. Rosenthal

The use of presplitting applications in an underground mine setting is a method of reducing overbreak in the rib and back when blasting occurs. Presplitting performed at the Underground Mine Education Center (UMEC) on Montana Technological University’s campus in Butte, Montana showed a dramatic decrease in the amount of overbreak incurred in the blasting process. Application of the presplitting technique occurred after presplitting presentations at ISEE in San Antonio. Presplit testing consisted of drilling perimeter holes closer together than production holes and loading perimeter holes with a combination of specialized presplit explosive and packaged emulsion with electronic detonator initiation. The ideology was to shoot the perimeter row first, to create a fracture around the perimeter, so when the main production round is shot there is less shock exerted on the surrounding walls due to the pre-fractured perimeter rock. For the test performed, the back ended up with 83% of total holes resulting in half barrels representing a remarkable result. The right rib ended up with one half barrel visible before muck was removed while the left rib did not have any half barrels visible due to a clay seam being in very close vicinity to the perimeter row. The first test blast was a great start encouraging future work on presplitting applications in the UMEC. Additional testing will continue with different combinations of perimeter hole spacing, the addition of a buffer row along the ribs, and varying loading techniques to determine the most effective presplit method for the rock type of the UMEC. Detailed test results and loading configurations will be provided in the paper.

Jan 1, 2024