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By Terry Matts, Henry Heidrich, Cluny Randell, Carl Kottmeier

Until 1990, all production of asbestos ore at Cassiar was by open-pit methods. With the impending exhaustion of open-pit reserves, a decision was made in February 1988 to continue mining underground, using the block-caving technique.

Jan 1, 1992

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 Alex Jankovich, Darren Thornton, Sarrna Kanchibotla, Cam Grundstrom

The Porgera joint venture and Dyno Noble have commissioned a joint project to optimise the drill and blast operations to increase the overall profitability of the mine. One of the aims of this project is to increase the throughput of semi autogenous (sag) mill by optimising the blast fragmentation, The work done so far clearly indicates that significant improvements in sag mill throughput can be achieved by optimizing the blast fragmentation. This paper discusses the planning, implementation and results achieved so far in this project.

Jan 1, 2001

By Tom McDonald, Rodney Burke

As mining progresses in the West, the depth of material has increased, making highwall stability a major factor in safety and production. The Jim Bridger Coal Mine has made highwall stability a priority, concentrating on safety as well as increasing and improving production. Overburden depths are increasing dramatically; the geological environment consists of medium to soft material, faulting, water, and current pit alignment not favorable to joint planes. Angle drilling the presplit at 20 degrees became necessary as vertical presplit drilling produced wall failures.

Jan 1, 1997

By Larry R. Fletcher

The Bureau of Mines obtained blasting accident data from the Mine Safety ant Health Administration (MSHA), U. S. Department of Labor. These data were analyzed to determine the most frequent causes of accidents in mine blasting. Accident totals for 1971 through 1981 are tabulated for metal-nonmetal and coal mines both surface and underground. In the past 11 years (1971-1981, inclusive) there has been an annual average of 9 fatal and 121 nonfatal blasting accident victims. Underground mining averaged 6 fatal and 93 nonfatal injuries each year.

Jan 1, 1983

By Quian Liu

The problem of cross-hole explosive malfunctioning in rock blasting (including sympathetic detonation, desensitization and cut-offs) is a function of delay and spacing in a blast which should be designed to avoid such occurrences. On a delay-spacing chart, the phenomenon of explosive malfunctioning is explained by dividing the chart into different regions, while the shape and size of each region could vary from one explosive to the other. Over seventy blasts have been carried out at the CANMET Experimental Mine to identify the malfunctioning characteristics of specific emulsion, water-gel and dynamite explosives. In each experiment, two parallel blastholes, 32 mm in diameter and 1.7 m deep, were drilled downwards in an underground drift.

Jan 1, 1994

By Stephen H. Chung

Direct visualization of rock movement during blasting is an important key to understanding the blasting process, as well as optimizing blast designs and explosives performance. To achieve this, a digital camera system (HSIS-500) has been built. It is a custom made high speed solid-state camera employing an advanced charge coupled device (CCD) and dynamic random access memory (DRAM) technologies. It handles like a regular video camera but requires no film or tape as the image is recorded in digital form on memory chips and transferred to the system hard disk for storage. The system consists of two components: the camera body and hardware, and the image processing unit.

Jan 1, 1996

By Romel B. Villanueva

At the Yanacocha gold mine, in the Andes of northern Perú, the first instrumental tests were carried out in October 2019 to detect the initiation sequence of a production blast by detecting the EMF signal produced by the detonation from each blast hole in the sequence. Several experimental tests were carried out to choose the correct antenna and find the best setup of the high-speed Data Acquisition device (DAD) to detect these electromagnetic waves. Finally, the first measurement was obtained. With the instrument recording at a rate of 1 million samples per second, the initiation sequence was detected with 99.5% accuracy. It was found that it corresponded, without a doubt, to the designed scheme. The main result is that these tests provide us with a method and instrumentation to verify if the planned initiation sequence is carried out correctly in the field. In this way we can find operational deviations and detect possible misfires. This method has proven to be accurate, fast and easy to implement, mainly requiring an EMF signal capture equipment that can record at very high speed, something that is increasingly easier to satisfy with the development of microcontrollers. On the other hand, the type of antennas used in this method are low cost and very commercial. These tests have improved our understanding of the nature of detonation and have marked a new milestone in the development of blasting instrumentation in Peru.

Jan 21, 2025

By P. Katsabanis

Numerical modelling was used to examine damage in wall control operations. Decoupled charges appear to create larger damage zones than fully coupled low density charges with similar charge distributions: Air was shown to be a very efficient coupling medium, while water coupling resulted in significant damage. However, Mach stems are formed when air is used as a decoupling medium, leading to compression of the charge ahead of the detonation wave. Air decked charges generate two damage zones, one close to the charge and another close to the air-deck/stemming interface, where pressure pulses are reflected. The extent of the latter depends on the length of the air-deck.

Jan 1, 2001

By Thierry Bernard, Pierre M. Vuillaume, Michel Kiszlo

In the context of its studies for the french ministry of the environment and for the French national coal board, INERIS (the French institute for the industrial environment and hazards, formerly CERCHAR) has made a complete critical survey of the methods generally used to reduce the levels of blasting vibrations.

Jan 1, 1996

By Mark S. Stagg, Rolfe E. Otterness, Stephen Rholl

The Bureau of Mines is engaged in research to develop and test high explosive fracturing and rubblization techniques that will enhance ore body permeability and thus increase recovery during in situ mining. The natural permeability of many ore bodies is too low to allow successful in-place leaching. These deposits could be profitably mined if flow rates of leach solutions could be increased. Blasting represents a potentially low-cost and effective permeability enhancement technique.

Jan 1, 1991

By Virgil J. Stachura, Larry R. Fletcher, Paul V. Sterk, Matthew N. Plis

The large diameter blastholes now being used in underground mining have caused concern because of their increased potential for damaging openings and creating rockfall hazards. In response to this situation, the Bureau of Mines is conducting research to reduce the amount of overbreak and damage to the perimeter of underground openings. This paper presents the results of tests with decoupled charges in 6.5 inch diameter blastholes, and unloaded guide holes, in Vertical Crater Retreat (VCR) stope panels at the Homestake underground gold mine in Lead, SD.

Jan 1, 1991

By Malcolm Scoble

The estimation of digging, ripping and blasting requirements in advance of mine production is a difficult task. The characteristics of the superficials and rock mass govern the type and intensity of ground preparation required as a prelude to loading. The incentives for optimum planning of preparation are primarily economic but also relate to mining method and equipment selection, productivity and environmental impact.

Jan 1, 1985

By Kamal Wadhwa

Ever since the introduction of Liquid oxygen explosives in India in 1927, these explosives are being extensively used in the various mining industries such as coal, ironore, limestone, bauxite, magnesite etc. The earlier LOX compositions were based on cellulosic material of Weberlox series of French origin. They contained the basic ingredients of saw dust with an admixture of cork dust, some hydrocarbons and some metallic powders. However, there were some inherent defects in the soaking characteristics of these compositions, in as much as, absorption and retention of liquid oxygen in the cartridges were not properly regulated in the fine pores and in the inter-granular spaces inside the ingredients in a uniform manner.

Jan 1, 1989

By Rob Farnfield, Mike Kelly, Toby White

There are a variety of sources of dynamic stress which can affect a building and give rise to cracking. A two-storey house, situated in the middle of a surface coal mine was monitored for a period of 30 months to attempt to identify the major causes of cracking. The factors described as environmental include internal and external temperature, humidity, wind speed and direction, rainfall and water table level. These were monitored using a weather station and piezometer and recorded every 20 minutes. The other factors are vibratory and include normal household movement (walking, shutting doors etc.), vehicle vibration and blast vibration. All the significant vibrations in the house were recorded using four sets of velocity transducers and accelerometers.

Jan 1, 1993

By P Cotton, N Cox

The Brisbane City Council has implemented a program of continual improvement at its Mount Coot-tha Quarry in the heart of Brisbane, Australia. The program has been underway for the past 6 years, and has resulted in very significant improvements in terms of both the cost effectiveness of its operation, and in terms of its environmental impact on nearby residents. The work has included a focus, amongst other things, on blasting efficiency, and has challenged conventional thinking in terms of the size of blasts fired, the frequency of firing, the diameter of blastholes, and the use of bulk emulsion or slurry explosives.

Jan 1, 1995

By Gary B. Hemphill

Estimators will agree that estimating for excavation is the most difficult costing task. Equipment costs and production rates are the toughest to determine. The following illustration is a method that can be used for this determination.

Jan 1, 1976

By D K. Joyce, B Mohanty

In a previous paper, it was shown that a lack of clear understanding of the role of initiation mode on detonation characteristics often leads to under-utilization of the explosive system in blasting. This is of particular significance since the very large number of explosive initiation practices currently in use implicitly assumes that the blasting performance of an explosive is largely independent of the exact mode of initiation. This paper deals specifically with bulk-loaded and pneumatically-loaded ANFO under various initiation modes in small diameters. These include initiation by booster and detonating cords of various strengths, and combination of cords and boosters. The nature of energy release and energy partitioning between shock and gas energy have been studied in the underwater test as a function of charge diameter. The paper describes the relative merits of various initiation modes for specific charge geometries and confinement, under end- and side-initiated conditions. Guidelines have also been formulated for use in the field to match initiation practice with blasting requirements.

Jan 1, 1994

By Daniel Haines, Benjamin Konshak, Michelle Crull

American Technologies Incorporated Group (ATI) is the prime contractor with U.S. Army Corps of Engineers, Huntsville Center (CEHNC) in the Honolulu District for the removal of munitions and explosives of concern (MEC) at the Former Waikoloa Maneuver Area. The site is approximately 123,000 acres on the Big Island of Hawaii, which was used as an artillery firing range with live ammunition and other explosives deployed. ATI utilizes state of the art metal detection equipment to find and excavate metallic anomalies that have hazard potential. Both the investigation and disposal procedures present challenges due to residential communities and archeological sites that are located in and around the site. In order to excavate metallic anomalies safely and without adverse impact, ATI utilizes CEHNC-designed, open front barricades constructed of sandwiched sheets of aluminum with a support structure. When munitions or explosives are located, ATI is responsible for safe disposal using shape charge perforators to detonate the item where found. Sandbags are used for mitigating the effects of all detonations.

Jan 1, 2008

By Michael Swisdak, John Tatom

In a quantitative risk assessment (QRA), the ability to accurately model real-world situations is obviously critical. In the end, the model must be able to represent the effects produced by the detonation of the donor and the consequences on the target. The science that goes into such a model must be carefully thought-out and based on as much data as possible.

Jan 1, 2007