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By J J. F Smith

The application of pneumatically loaded ANFO for underground mining has continued to increase year by year since the technique was first developed and introduced underground during the early 1960's. Improvements in the manufacturing process for explosives grade prills, the design and construction of more efficient AN prill-fuel oil blending equipment, and the introduction of more durable and reliable pneumatic loaders have promoted the wide application of the relatively low cost blasting agent, ANFO.

Jan 1, 1982

By Andrew Ritter, Victor I. Montenyohl, Stephen R. Winzer

Thirty-seven open pit production blasting operations have been monitored using high-speed cameras running between 500 and 7000 frames per second. Analysis of the resulting films reveals irregularities in timing including sequencing errors and crowding (holes firing less than 8 ms apart), confirming results of laboratory testing of ms delay blasting caps (Winzer, 1978). Where blasting parameters are otherwise constant and within recommended guidelines (stemming, spacing, burden, etc.), timing problems dominate the overall performance of the blasting operation. Model tests in layered Homalite 100, designed to simulate joint or bedding planes in rock, indicate the importance of the stress waves generated by the explosive in developing the crack network which is ultimately responsible for the fragmentation seen in the resulting muckpile. These mechanisms are strongly supported by high-speed film studies at Pinesburg, Maryland. Experiments in controlling relief in deep shots (where depth approaches the lateral extent of the bench blasted) using borehole geometry and hybrid initiation systems (electronic timer and pyrotechnic delays) were carried out. The results suggest that the 1 me/ft. of burden guideline developed by Bergmann et aI., 1974 is too short, and that much longer times are necessary to optimize fragmentation and muck digability. Longer times are found to reduce noise, vibration, and flyrock.

Jan 1, 1979

By L. O. Souza, J. F. Gewher, M. P. Scussiatto, C. S. Mendonca, R. A. McClure, B. T. Kuckartz, J. Kloeckner

Blasting is the most effective and economical tool available to fragment and move rock for most applications. If properly executed, it can improve down-stream operations such as loading, hauling and crushing. It is not possible, however, to have full control over the energy released by the explosives when a poorly designed blast pattern is used. A poorly designed blast can produce serious damage to equipment and create a potentially hazardous condition to people. Advanced mining technology has been developed to address these potential hazards and optimize the blast pattern. This profiling technology can assist with blast planning and provide quick, precise data about the condition of the rock structure to be blasted. The 3G BlastMetrix system presented here uses three-dimensional (3D) stereo photogrammetry to model the rock mass in a fast, practical and safe manner. Through the image overlapping method, a 3D model is created with thousands of points that provide a significant amount of data regarding geology, geometry and topography conditions. The blasting plan can then be made in a way to optimize the rock fragmentation and avoid areas that could create flyrock. This paper is a case study concerning usage of stereo photogrammic surveying and borehole survey systems in a blasting operation at the Brazilian Quarry, Incopel. One 3D image of a drilled bench was generated using photogrammetry survey technology and the borehole survey data collected using the rodded Boretrak borehole survey system. Utilizing the minimum burden profile reports, explosive loading could be done accurately, resulting in an optimized blast with good heave and fragmentation as well as increased safety.

Jan 1, 2013

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 Conny Postupack, Jim Petrunyak, John Hope

The authors discuss the concepts, engineering considerations, and cost relationships involved in the use of drilling and blasting to accomplish backfilling and reclamation with minimum use of mechanical equipment. The four xchods o f reclsnacisn now in use are reviewed, and their advantages and disadvanrages a r e nocea. Guidelines for seleccrng a particular method are offered in terms of applicability under varying geologic, economic, and technological condirions.

Jan 1, 1989

By Travis Davidsavor, Stanley: Dong Vitton

Concrete is a common construction material used throughout the world, and with increasing demand of fast-track construction, blasting and concrete casting are occurring simultaneously at many sites where rock is being excavated for concrete placement. However, there has been significant disagreement in the construction industry as to what intensity of shock vibrations green, or fresh concrete can tolerate. Peak particle velocities are often arbitrarily chosen, or are simply based on materials such as plaster and drywall that have been more thoroughly studied in relation to damage. Previous research on green concrete has used the concrete’s static strength subjected to shockwaves at different ages as the primary damage criteria. In addition, the static strength tests have been based on curing time. However, changes in temperature or humidity can dramatically alter the hydration rate, which affects strength development of different cements. To account for temperature changes and humidity the concept of concrete maturity is commonly used and allows the researcher to see where the concrete was in terms of hydration progress. In general, static testing determines the failure stress that the concrete’s macrostructure can handle, and often failure occurs in the natural materials first or along large defects in casting techniques. Dynamic testing or high strain rate testing, on the other hand, loads materials at such a high rate that larger defects do not have time to react and instead the microstructure is more highly stressed leading to higher strength and stiffness values. This is known as the material’s strain rate sensitivity. Since dynamic testing better tests the microstructural strength, it is believed that it may provide a better way to assess damage to green concrete. Testing includes both static and dynamic compression as well as static and dynamic splitting tensile strength to assess whether damaged has occurred to the concrete. No significant statistical evidence was discovered that damage to the concrete occurred at five different “green” maturities from peak resultant velocities ranging from 10.66 in/s (271mm/s) to 4.40 in/s (112 mm/s) with average intensity of 6.7 in/s (170mm/s).

Jan 1, 2003

By John P. Ashby

Production blasting is a process of destruction of rock masses in order that ore may be extracted. Many open pit operations are faced with the apparently conflicting requirements of providing large quantities of fragmented rock for the processing plant and of minimizing the amount of damage inflicted upon the surrounding pit slopes. A reasonable compromise between these two conflicting demands may often be found by means of simple engineering of production blasts.

Jan 1, 1980

By Alan Tordoir, Mark Roberts

The drill and blast process is a critical function within the production cycle which significantly impacts the ability of an operation to effectively meet its safety and production targets. Acknowledging that D&B design and reconciliation practices were conducted inconsistently across operations, a Group wide initiative was launched to embed a standardized design and reconciliation platform in line with the company’s Operating Model principles. A technical system was selected to deliver the digitalization of critical D&B information and enable ‘analyze and improve’ routines for design compliance monitoring and downstream productivity optimization.

Jan 1, 2019

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 David Kennedy, Noel Hsu, Miguel Araos

The use of bulk explosive for mining applications started in the 50’s. Since then millions of tons of that material have been transported by road. However during that time, there have been several road incidents involving them. This type of incident has forced the explosives manufacturers as well as regulatory organizations to look for a better classification of explosives in order to regulate the industry as well as to mitigate community concerns over the classification of mixtures of substances that are regarded as precursors to explosives.

Jan 1, 2006

By Carl Hendricks

AQUILA Mining Systems Ltd. is the world leader in drill monitoring, control and GPS based drill navigation systems for the mining industry. This paper will review the general design and application of AQUILA.s drill systems currently in use throughout the world and the key benefits that derive through their use.

Jan 1, 2002

By Jeff Wachendorf

As the title implies, this paper details the start of a cast blasting and the design flexibility required to satisfy different parameters encountered on a large coal mine employing cast blasting as the program has grown and evolved around the town of Colstrip, Montana. As strip ratios have increased, the need to adapt and find solutions to provide coal at a reasonable cost to the mine mouth power plants has risen. Colstrip, Montana has a long history of coal mining which dates back to the early 1920s when Foley Brothers began supplying coal strictly for powering locomotive engines.

Jan 1, 2015

By James Ballard, Charles H. Dowding

Recent Office of Surface Mining regulations have called for pre-blast surveys of residences within one-half mile of blasting. Unless lighting effects and the multiple origins of cracks are recognized, hurried (lowest bid price) pre-blast surveys may be more harmful than beneficial. Unrecorded, but pre-existent, cracks can be noticed by homeowners during blasting under special lighting conditions. This paper discusses important factors to note during pre-blast surveys, presents data collection forms and discusses the importance of photographic technique in recording cracks (both present and previously patched).

Jan 1, 1979

Almost one half of Canada's total land surface is underlain by permafrost. This term describes the thermal condition of earth materials when their temperature remains below 0°C continuously for a number of years. The drilling and blasting of frozen materials requires more energy than the blasting of same in its unfrozen state. The cost of comminution could double in permafrost even with adequate organization, drilling equipment and proper explosives.

Jan 1, 1975

By Advanced Initiation Systems Inc

10 years in R&D Last 5 years available commercially Worldwide Met strict approvals for manufacturing and use

Jan 1, 2004

By Jack Eloranta

This paper describes a method of evaluating shot performance through the use of available mine- data. The mine had already been monitoring the following parameters for other purposes: drill penetration rates, shovel loading rates, crusher throughput, crusher power and crusher hangups. By assigning pit coordinates to these factors, maps showing the location of difficult and favorable blasting are as are identified. Products and techniques are compared by the same method.

Jan 1, 1993

By Mark S. Stagg, Siskind David E

The mining industry occasionally blasts near pressurized transmission pipelines and has requested guidance on safe vibration levels and setback distances. The Bureau of Mines and the Indiana Department of Natural Resources cooperated with AMAX Coal Company on a study of coal mine overburden blasting. Five buried and pressurized 250-ft pipeline sections were specifically installed on the Minnehaha Mine highwall near Sullivan, IN for testing to failure. Four welded steel pipes ranging from 6- to 20-in diameter and one 8-in PVC water supply pipe were monitored for vibration, strain, and internal pressure for a period of 6 months while production blasting advanced up to the pipeline field. In contrast to previous studies of small-scale blasting representing construction activities, these tests involved overburden blasts of up to 2100 lb per delay in 12-1/4-in diameter holes.

Jan 1, 1993

By Matthew Baumann, Bahram Sameti, Tafazoli Zeng Hairong, Edmond Chow

An automated, centralized, image-based rock fragmentation analysis system provides blast engineers with the benefit of minimizing tedious and mundane work, and allows them to focus on their expertise of blast optimization. In typical manually-operated image-based rock fragmentation analysis, much time is spent on collecting proper images, handling and transferring data, and processing for fragmentation.

Jan 1, 2013

By Mike McGill, Stephen Chung, Dale S. Preece

Cast blasting can be designed to utilize explosive energy effectively and economically for coal mining operations to remove overburden material. The more overburden removed by explosives, the less blasted material there is left to be transported with mechanical equipment, such as draglines and trucks. In order to optimize the percentage of rock that is cast, a higher powder factor than normal is required plus an initiation technique designed to produce a much greater degree of horizontal muck movement. This is a significant change from normal blasting practice where fine fragmentation and sufficient muck movement were the prime requirements to permit efficient excavation.

Jan 1, 1994

By Kunihisa Katsuyama, Yuji Ogata, Yuji Wada

Test blasting was carried out to study the flying characteristics of rock mass caused in bench blasting. The quantity of explosives was increased from 7.6kg to 9.1kg and the Minimum burden was changed from 131mm to 451mm. The effect of condition for the characteristics of fly rock were considered. The fly rock was observed using the high-speed camera and video to study the flying characteristics of the rock mass caused in the bench blasting. Numerical simulation of fly rock was carried out using DDA (Discontinuous Deformation Analysis) method. It was clear that the DDA method can be applied in the simulation of fly rock caused in bench blasting.

Jan 1, 1997