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By E. Contestabile, B. von Rosen

On August 5th, 1998, a tractor-trailer carrying approximately 18,000 kg of blasting explosives, struck a rock face on the side of the road near the town of Walden, Ontario. Eye-witness accounts of the incident state that there was an intense fire for approximately 30 minutes before the detonation. The detonation caused severe damage to the tractor-trailer, shifted the pavement and caused blast damage to the rock face. A rock fragment was recovered almost 2.5 km from ground zero and a 70 kg piece of an axle assembly was recovered over 1 km from the site. Windows were cracked at distances of almost 3 km.

Jan 1, 2001

By H Fukui, K Ichikawa, K Aikou, E Suzuki

An electronic delay detonator (EDD) consisting of a digital-base electronic delay module and a conventional instantaneous detonator module, designed for series connections with a special adjustable-output blasting machine, is described and shown to provide a delay time accuracy some four to twelve times higher than that of pyrotechnic millisecond and decisecond delay detonators, together with the other performance characteristics necessary for practical use. Also described is a blasting design system which allows effective reduction of ground and air vibration, through the use of EDDs with optimum delay times as determined by accurate computer simulation based on wave form and other data obtained from an on-site single-shot test blast.

Jan 1, 1989

By Dale S. Preece

A discrete element computer program, DMC (Distinct Motion Code), has been used for several years to simulate blasting-induced rock motion. Recent enhancements of DMC's capabilities have included addition of an algorithm that couples together rock motion and gas flow. This allows the user to specify a particular explosive which also specifies equation-of-state and other parameters necessary to model explosive gas flow from the blastwell. Rock loading by the flowing gas is calculated automatically. The mechanism for calculating the rock loading is the subject of this paper. The rock motion effects the gas flow calculation by changing the porosity. DMC is currently being used on a SUN SPARCstation 2 computer workstation.

Jan 1, 1993

By Sanjay Sengar, Nabiullah Pingua, Saurabh Sahay

In India, more than 80 percent of the total of 557 million metric ton coal production comes from open-cast mines involving large overburden removal with average 1:3.5 stripping ratio which is going to in-crease in future. This operation consumes nearly 0.5 million metric ton explosives consisting of 80-85 percent bulk explosives and remaining 15 to 20 percent non-permitted large diameter explosives. Quali-ties of bulk explosives play an important role in rock blasting. Post blast results like poor fragmentation, tight mucking, toe problems, improper muck profile and lower productivity of mine may require chang-es in explosive loading factor (amount of explosive used per unit of rock blasted ). The explosive load-ing factor is an extremely important index to assess the economy of blasting operation.

Jan 1, 2014

By Finn Ouchterlony, Gert Bjarnholt, Robert Holmberg

A system for contour blasting with a linear shape charge principle has been studied /10/. In one operation the charge creates two notches along the bore hole wall and breaks the rock mass. The built in notching capability makes it possible to reduce the specific charge and the bore hole pressure to 1/3 of what is used in conventional contour blasting and to ensure that cracks are initiated and propagated only at the notches and nowhere else. The notching capability of linear shape charges has been studied experimentally and the bore hole pressure calculated to aid in optimization of a charge for future field experiments in bore holes with a diameter of about 50 mm.

Jan 1, 1983

By Tapan Goswami, Michael Croucher

At Bayswater Colliery various methods of controlling highwall stabii were investigated. The use of presplitting was trialled and its effectiveness measured. The presplit hole spacing and explosive charge were based on those succes& lly used in other coal mines in the Hunter Valley. The major presplit design parameter to be determined was the stand-off distance between the presplit line and the back row of the production blast. This could not be transfmed directly from other sites due to the difference between the Bayswater’s production blast geometry and geology to that of other sites. Using highwall face surveys and Orica’s SUR..YPlus@ software, the average back-break behind normal production blasts was determined. This was then used to select the stand-off distance between the back row production blastholes to the presplit line. While presplit designs are normally based on powder factor (kg/m2), the use of energy factor (MJ/m2) was also investigated as a possible design criteria.

Jan 1, 1999

By Marco Antonio Falquete

Conventional detonators and blasting caps make use, as igniters, of flame-shock-, andfriction-sensitive primary explosives, such as lead azide, lead styphnate, mercury fulminate, etc, most of them severe toxic and environmental contaminants. Sensitivity of primary explosives is one of the main causes of injuries and fatalities in explosives industry and in field applications. Intense research for a reliable, safe, and environmental-friendly non-primary-explosives detonator was conducted by the industry in the last years. A new detonator is presented, containing no primary explosive, employing only environmental-friendly substances while keeping reliability of performance. A series of performance tests is executed in prototypes of different output energies, including initiation by flame, shock tube, thermo tube (IBQ’s proprietary spark-generating tube, presented at 2005 ISEE Conference), energy transfer reliability, and extreme environmental conditions (according to MIL-STD 331B, test C1 standards). Results are compared, when pertinent, with standard blasting caps of different energy outputs, and with standard primary explosives.

Jan 1, 2007

By Paul E. Thompson

Current magazine regulations are designed to avoid injury or property damage caused by accidental detonation as well as to store explosives securely. The primary emphasis appears to be the avoidance of unintended detonation or in the event such detonation occurs, the avoidance of damage to surrounding property. Adherence to these regulations largely serves the purpose intended but has caused difficulty in magazine sitting in built up areas. To the extent that magazine siting is too heavily restricted, other more significant dangers such as storage of explosives in more dangerous and less secure places may be encouraged. In summary, the regulations have served rural magazine locations well but may need further study for urban settings.

Jan 1, 1990

By Carlos Agreda

"It is widely accepted that the rock blasting results are a function of several stochastic variables given by: -The natural geological structure of the rock mass (joint spacings, discontinuities length orientation and characteristics, physical-mechanical properties, such as: ultimate strengths and elastic properties, etc.).-The detonation and explosion parameters of the explosive mixture (V.O.D., P2, T2, Q3, etc.).-The drilling and blasting pattern dimensions.-In this paper the most important stochastic variables regarding with the rock mass and the blast design dimensions before mentioned are identified, described and discussed.A non linear programming method to calculate the optimum burden Bo) is proposed and discussed.The great impact of the stochastic variable called burden (B) on the rock blasting results is emphasized. A comparison between burden theoretical calculations and some field blast results is also shown."

Jan 1, 1996

By James Stuart

Explosive components are common in electric power distribution systems. Basically, we use explosives either to open or to close a circuit very quickly, in order to avoid electrical catastrophe. We use explosives in these important applications, because explosive materials are compact, inexpensive, long-lived, powerful, and can be triggered instantly. A lead-alloy fuse will melt when excessive electric current passes through it. A small fuse of this type melts quickly. However, a lead-alloy fuse for high current levels must be larger, and takes longer to melt. Thus, at high current levels, a lead-alloy fuse offers inadequate protection, because electrical catastrophe might happen, before the fuse melts. We need faster-acting, explosive components.

Jan 1, 2009

By G J. Kulbieda

The Empire Mine initiated production in 1963. Since then the unit operations of drilling and blasting have evolved continually in order to meet the increased mining requirements demanded by plant expansions in 1968, 1973 and 1980. Additionally, advance mine planning has become an integral part of proper pit development and is necessary to insure uniform blending of the distinct ore horizons contained within the mine area. Blasting practices have been modified to facilitate the autogenous grinding system utilized at Empire and pioneered in the Iron Ore Industry. Technical innovations in the explosives industry, as well as, progress regarding on site blast engineering methods have substantially increased the use of ammonium nitrate explosives and helped to establish efficient charging procedures. In addition, the recent introduction and use of ammonium nitrate fueled with nitropropane and methanol indicates that it is a viable substitute for aluminized ANFO.

Jan 1, 1981

By Paul V. Sterk

In the early 1980's, the Homestake Mine converted from labor intensive methods such as open cut-and-fill mining to Vertical Crater Retreat (\/CR) bulk mining and mechanized cut and fill. This transformation occurred as a result of high costs and low productivity associated with open cut-and-fill mining. Use of Vertical Crater Retreat allowed Homestake to contain waste development rock within the mine to further decrease costs since the voids created from VCR stopes provide a good receptacle. The need to access these voids from surrounding development to facilitate waste dumping precipitated the development of drop raising. This system is cheaper than raise boring because it allows drilling into the top of an open stope without the expense of raise boring cutouts or equipment. It's safer than conventional raising since access from the bottom is not required. Two methods of long hole raising or "drop" raising have been successfully developed at the Homestake Mine and can be categorized as Ring Drill Drop Raising using 2-1/4 inch holes and VCR Drop Raising using 6-1/2 inch holes.

Jan 1, 1991

By S Lukovic, Robert Briton, Calvin J. Konya

Investigators have reported that charges which are decoupled from the borehole wall produce different fragmentation then those which are fully coupled. The difference in effect could be as a result of energy doss during transmission across the air gap or it could be due to the change in detonation characteristics of the explosive as a result of the change in confinement on the charge during detonation. In order to better understand the phenomena of decoupling, a research project was conducted at the United States Bureau of Mines Station, near Pittsburgh, Pennsylvania. It was decided to use shock and bubble energy tests along with simultaneous velocity measurement to determine the mechanics of decoupling and energy transmission. Two explosives were selected for the test, one dynamite and one water gel. Test results indicated that decoupling could both boost the total energy output of the explosive and that further decoupling would drop the energy output.

Jan 1, 1987

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 Peter Bellairs, Anthony Bubb

The Porgera Gold Mine is located at an altitude of 3000m in the central highlands of Papua New Guinea some 600 km Northwest of Port Moresby the capital city. Access to the mine is via a five hour trip on an unsealed road from Mount Hagen the nearest regional centre or 40 minutes via air. The mine operates on a fly in - fly out basis and currently produces ore from both opencut and underground operations with the former providing the bulk of the mill feed. Opencut mining utilises conventional truck / shovel, drill and blast methods on both 10 metre and 14 metre bench heights with the larger benches being restricted to the stripping areas. This paper presents the strategy used and the results of a blast optimisation process in the opencut that was a joint effort between the mine personnel and the explosives manufacturer/supplier.

Jan 1, 1997

By R W. Givens

This paper presents blast casting design variables that have been developed and are currently being used at the High Power Energy mine in West Virginia. The shot specifications are summarized in Table I. The two active casting pits were designed with casting in mind and as a result are better designed and more efficient. About 55% of the overburden material is effectively cast and clean up is done by a bulldozer, front-end-loader, and trucks. This results in a 15X decrease in the cost of coal production.

Jan 1, 1988

By Roy McKinstry, Mark Rantapaa, Thomas Bolles

In March of 2001 Barrick Goldstrike Mines, Inc. began evaluating the potential benefits of electronic detonators at the Betze Post open pit gold mine. The original evaluation focused on increased fragmentation, and excavator productivity. During the original evaluation there was an attempt to quantify mill throughput. Early tests indicated that there would be a benefit to mill throughput, however management was hesitant to take on the added cost of electronic detonators based on the initial evaluation. In early 2002 a decrease in mill throughput was being forecast as a result of harder ore being encountered. As a result of the initial electronic detonator evaluation a team of individuals from the Open Pit and Process areas worked closely on the Drill-to-Mill (D2M) Continuous Improvement initiative. This initiative was targeted at improving mill throughput as the harder ores were encountered. Batch tests were conducted to determine if adjustments to drilling and blasting in the open pit could increase mill throughput and justify a 50% increase in drilling and blasting costs for the harder ore material.

Jan 1, 2004

By Pierre Allard, Wilfrid Comeau

Near-field and close-in blasting can be safe and efficient, near engineered structures, if the dynamic reaction of structural members to blasting vibrations are considered. Safe particle velocity criteria can be derived from allowable safe static flexural deflections and critical frequencies. Control of close-in blasting can be accomplished using low-pass filtering of the particle velocity signal at the critical frequency. The CETE Mediterranee laboratory at Aix-en-Provence, France, a branch of the Ministry of Roads and Bridges has -pioneered this approach and successfully applied it to major road cuts and tunnels in built-up areas, as well as a major powerhouse expansion project in Africa. This approach is presently being used for a spillway rehabilitation project in Quebec, Canada. This paper exposes- the theoretical aspects and gives case histories of its use. The SCS-15 an automated, peak reading, data acquisition device is described.

Jan 1, 1991

By Jaime Huidobro, Mervin Austin

The effect on an explosive column of the sharp transient stress waves generated during the earlier detonation of adjacent blastholes is of paramount importance to explosives users. Some explosives will sympathetically detonate under these stresses. Others may suffer a transient desensitization, arising from a temporary increase in the density of an explosive beyond certain limits and persisting until the explosive mass relaxes back to the original density. Some explosives are so adversely affected by these stresses that the product suffers immediate and permanent loss of sensitivity. These effects can be clearly seen while blasting in tough conditions such as burn cuts or wedge cuts and in materials, such as coals, that propagate shock waves well.

Jan 1, 1992

By S C. Brashear, D A. Anderson, A P. Ritter, S R. Winzer, R Broughton

Results of quarry blasts can be quantified to show the effects of controlled variables. Two studies have been carried out: one to document the effect of delay on fragmentation and the other to show the effects of higher relief patterns and more accurate initiators. By using such techniques as highspeed photography and timing studies of mucking and crushing operations, subtle differences in blasting efficiency can be measured and quarry blasting can be optimized. Given the range of available and developing blasting technologies, quarry operators should resort to quantitative analyses of their blasting practices to get maximum productivity.

Jan 1, 1985