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By Ashwani Jain, D K. Soni

Compressive strength of rocks is often required by mining engineers and quarrying authorities for blasting operations. Uniaxial compressive strength of rocks can be predicted with reasonable accuracy with the help of point load strength tests which can be easily conducted at site by the field staff, simultaneously as the cores are recovered from drilling operations. A number of diametral point load tests and uniaxial compressive strength tests have been conducted on the specimens of different rock types under air dried, and saturated condition as well to study the effect of ground water saturation on strength. It has been observed that due to saturation uniaxial compressive strength and point load strength get reduced to a maximum of 32 and 29 per cent respectively. It has also been observed that uniaxial strength is sixteen times the point load strength in air dried as well as saturated condition. However, this factor used for calculating uniaxial compressive strength may be reduced to a lower value for the safety of miners in field blasting operations.

Jan 1, 1994

By John Eloranta

This paper is a case study showing the assembly of available rock property parameters for the purpose of blast design. Blast optimization now includes subsequent milling and requires a full knowledge of the rock mass. Individual blast holes should be designed using all available data. The parameters include: geologic layer from diamond drilling, shovel performance, crushing plant experience from that area, drill monitoring, magnetic susceptibility from a downhole probe, size analysis history from digital image analysis, compressive strength tests of problem areas and cross hole sonic testing. Bedding thickness observed from drill core appear to have a strong influence on fragmentation.

Jan 1, 1996

By Tristan Worsey, Nathan Rouse, Daykin Schnell

The authors were retained by a proposed underground metals mine operation to evaluate the potential blast vibration amplitudes that could be generated at surface structures above the proposed mine. Literature reviews of published blasting documentation gave little information, data, or models on surface blast vibrations produced by underground mines. At the client’s request, the authors contacted a number of underground mining operations to evaluate interest in sharing blast vibration data with the authors so that the authors could develop an underground-to-surface blast vibration regression equation. The authors worked with three underground metals mining operations to collect surface blast vibration data produced by heading blasts and stope blasts. The data included blast vibration amplitude values, seismograph records, blast design geometry, charge weights, and detonator delay and sequence designs. The total amount of information was used to produce a regression equation and summary dataset that could be used by the proposed underground mining operation to evaluate blast vibration amplitudes that will be generated on the surface. This work is published and presented so that operations with proposed underground mines or proposed underground mine extensions can use these equations to predict vibration amplitudes on the surface above the mine workings before any blasting occurs.

By A N: Zditovetsky Shishov, M G. Menzhulin

At present in a building industry demand for products from granite, gabbro and other rocks, steady to erosion, natural and chemical weathering, was essentially increased. It has caused the enlargement of exploitation of stone block deposits and necessity of creation of new technologies of hard stone cut.

Jan 1, 1996

By Michael Wieland

Delay blasting in underground coal generates shock waves and rifting forces that damage charges remaining in the blast pattern. Damaged charges detonate poorly, raise fume toxicity and reduce coal breakage. Such circumstances could be prevented by using explosives resistant to cross-hole interaction damage. The design of rugged explosives is fraught with contradictory requirements, but tradeoffs related to hard-particle size characteristics prove useful. Hard particles, related voids or trapped bubbles represent reaction nucleation centers which strongly influence the performance of coal mine explosives.

Jan 1, 1992

By D J. P Jordan, C V. B Cuningham, A J. Rorke, C G. Ladds, O L. Davey

"During the early stages of the boxcut mining at the Arthur Taylor Colliery, Open Cast Mine(ATCOM), problems were experienced with blasting results. Very large boulders andportions of completely unfragmented rock were commonly encountered. A full blastmonitoring programme was instigated by the mine and the explosive supplier to solve theproblems and to optimise future blasting operations at the mine."

Jan 1, 1993

By Pat McLaughlin, J R. (Dick) Daniels

Current practice in establishing quarries in remote areas with hilly or mountainous terrain tends to the use of airtracs (or similar pioneering units) drilling horizontal holes to establish a face, followed by bench development with light excavating equipment. The authors propose the use of a hybrid coyote blast design that incorporates long-round tunneling techniques. This method would, in effect, use down-the-hole (DTH) drills to advance the drift cut to the final depth, allowing longer and more rapid drift advances, and replace the cross-cut drifts with clusters of DTH holes to achieve the same explosives distribution.

Jan 1, 1995

By R Mancini, G Borla

This paper analyses the first results of a part of an EEC research project ("Blasting control for underground mining"). This research that involves three universities (Paris, Torino and Leoben) has been carried out at the Eisenerz test mine in Austria. In the experimental campaign here reviewed, parallel holes rounds have been fired "decomposed", which means with enough delay between the explosions of the successive blastholes groups to allow for a separate evaluation of their effects on the rock. The seismic effects have been recorded by geophones placed at small distance from the blast, the aim being to find out correlations between the features of the seismogram and the good or poor performance of the single blastholes, or of the groups pertaining to the same delay. Indeed, the seismogram is the only safe and cheaply obtainable description of what happens during the blast. The seismogram should be transformed in a diagnostic tool in the round 'calibration' stage, and in a routine control device during excavation.

Jan 1, 1995

By Erik C. Nygaard

ANFO is the most used industrial blasting agent in the world, and is often used as a reference for comparison of other explosives. It is known to work very well under dry conditions in large borehole diameters, whilst in small bore hole diameters the formation of high amounts of toxic fumes (CO, NO and NOz) can result. In underground blasting, problems can also occur with reduced visibility caused by uncombusted ammonium nitrate.

Jan 1, 1999

By David Davison, Richard Johnson

Metal-oxidant blends are ordinarily unsuitable as diiect replacements for explosives, because the reaction occurs too slowly. Oxide coatings protect metals, preventing or delaying reaction. By contrast, the electrically-activated reactive composites described below are configured as metal fibers or foils in close proximity to oxidants, with continuous electrical paths from one end to the other. By quickly vaporizing the metal component with an electrical pulse, a reactive composite will be activated, and the reaction will occur rapidly.

Jan 1, 1999

Drilling through unconsolidated material I need to drill blastholes through a mix of consolidated and unconsolidated material. This material is hung up in an underground ore pass. The total length of the holes would be approximately 200 feet. We have attempted to drill through the material with conventional ITH drilling, but were unsuccessful. Does anyone have a suggestion? I am more than willing to bring in a contractor to do the job, if they have solid experience with this type of problem.

Jan 1, 2011

By Thomas L. Barkley, Michael A. Indihar

The new Cyprus Northshore Mining Co. has taken the previous blasting methods of Reserve Mining Co.'s mine in northern Minnesota and adapted them to a new competative Iron Ore Industry. Cyprus was challenged to develop new blasting methods to reduce costs and improve results over the previous mining operation. Many of the older procedures have been kept, but others have been changed in ways that bring the mine operation up to state of the art technology. In addition, unique ideas not previously tried in the North American Iron Ore Industry have been instituted. So far, this has reduced Cyprus's blasting costs by 70 percent.

Jan 1, 1991

By Dale Nies, David P. Childs

The open pit gold and silver mining operations in the State of Nevada have historically used simple row by row, echelon, or chevron delay patterns. Common practice has been to use detonating cord trunklines and either detonating cord downlines or nonelectric common in-hole delays in conjunction with surface delays. Several operations use a series of downhole nonelectric delays with an entire row loaded with the same delay to develop similar patterns.

Jan 1, 1991

Electronic detonators are receiving increasing acceptance in the blasting industry. Electronic detonators offer several distinctive features over electric and non-el (shock tube) detonators including better timing accuracy resulting in excellent fragmentation and vibration control, field programmability and digital safety means. Several electronic detonator systems are available commercially today serving the surface, underground and seismic needs.

Jan 1, 2010

By B J. Kennedy, G W. Sengstock

During the last two decades, many advances have been made in open cut coal mining technology as new mines have come on stream and old mines have faced increasingly difficult mining and operational conditions. The need for close control of operating costs has necessitated consideration of modified excavation methods.

Jan 1, 1995

By Shih Wen Wang, Ronald R. Rollins

A blast casting model is proposed to predict the burden velocity in bench blasting. This blast casting model is the first theoretical model that 1) explains the throwing procedures and mechanisms, 2) uses the explosion pressure as the primary source in throwing rock fragments, 3) applies them to field conditions successfully. Also the predicted burden velocities are based on the rock properties, the explosive properties, and the drilling and initiation patterns. This blast casting model is programmed into a computer software "ROCKFRAG". The comparisons between "ROCKFRAG" predicted values and two field test data are in good agreement.

Jan 1, 1992

By Brendan O'Reilly, Outokumpu Zinc, Geoff J. Johnston, S Durucan

Historically vibration monitoring has dealt primarily with surface blasting or "near field" monitoring of underground blasts. The Situation at Tara Mines is different, blasting occurs up to 400m underground, with a number of blasts occurring daily and occasionally with residential properties directly above the blasting site. Tara Mines, due to both its location (1.5 km from the rural town of Navan) and stringent planning conditions have always had to monitor, carefully plan and control the levels of vibration from blasting. The statutory vibration limit at Tara allows a maximum peak particle velocity of 7.62 mm/s with no frequency limitations. Levels of vibration have been monitored continuously since mining operations began in 1972.

Jan 1, 1994

By Scott G. Giltner, Alex Schwenk

This paper is an update on a paper presented at the 2022 ISEE conference. The original paper presented how the mine operator desired to open up ore reserves near several mine structures including two crushers, the conveyor belt drive and the concentrator thickeners. In order to open up additional ore for extraction (over 3 million long tons or 3 million tonnes) it was necessary to blast out two benches near the mine structures. Since the two benches have been successfully shot, the mine has now conducted nine production blasts in this area at distances as close as 116 m (380 ft) to the two primary crushers. These production blasts are full size production blasts consisting of up to 300 or more blast holes. For these blasts the two primary crushers were still the critical structures as they were the production life blood of the mine. If the crushers were shut down due to any damage from the blasting, the revenue of the mine would be adversely affected. As with the initial bench blasts, two issues provided an extra challenge to the blast design. The first was that the blast holes were still considered large diameter at 12¼ inches (311 mm) and 16 inches (406 mm). The second issue was that the bench heights were short, with the average varying from 34-40 ft (10.3-12.2 m). This combination of large diameter blast holes with a short bench provided an unfavorable geometry for the goals established by the mine management. The mine management established the following goals. 1) None of the mine structures would be damaged by fly-rock. 2) Minimize the blast vibrations at the crushers. 3) The last goal was to produce a muck pile that could be dug easily by hydraulic shovels. Electronic detonators were applied to achieve the necessary control of the blast and optimal fragmentation throughout the mine. UAV surveys of the blast area were also conducted to provide a 3-D representation of the free faces and bench surface. The 3-D point cloud produced from this was used to measure the shape of the free faces. Once the shape of the free faces was quantified, it was possible to establish proper placement of the crest holes and develop a custom explosive load for each blast hole. The results of the nine blasts have provided what the customer requested. The peak vibration level at the crushers for the nine production blasts was 1.6 in/s (40.6 mm/s) at a frequency of 18.9 Hz. There have been no fly-rock or blast vibration issues at any of the nearby mine structures. As a result, the mine has been able to maintain its production with no downtime. The muck piles have been well fragmented with reports from the shovel that they have all dug well.

Jan 21, 2025

By Andre Pinsonnault, Francois Lefebvre, Yves Newman

In 1989, Les Entreprises Kiewit Ltee signed a C$32 million contract with the Societe d'energie de la Baie James, on behalf of HydroQuebec, to excavate the intake and tailrace channels for a second powerhouse at the LO-2A James Bay hydroelectric project. The multistage contract included removing three marine rock plugs. The first plug was blasted in April 1990. It was a 43 yards wide, triangular shaped wedge that projected into 18 yards of water. Located at the mouth of the intake channel, it contained over 72,000 yd3 of rock, more than twice the 30,000 yd3 found in most rock plugs.

Jan 1, 1991

By Ray Jambakhsh, Craig Copping

The St. Lawrence Seaway's Welland Canal has been undergoing a rehabilitation program that requires the removal of deteriorated concrete from the 25 meter high lock walls. Multi million dollar contracts must be completed during the three month winter freeze up. New blast designs have drastically cut the time required for concrete demolition. All blast results including vibration, noise, underbreak, overbreak, scaling and flyrock have been improved and at a lower cost.

Jan 1, 1994