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By R Ludeling, Klaus G. Hinzen, Ulrich Steiner, Friedrich Heinemeyer, Peter Roh

A method for hybrid modelling of blast vibrations in time domain is developed. Field seismograms of single shot experiments are combined with computer simulations. In this way firing times of blastholes in a pattern can be optimized due to diverse criteria like maximum velocity amplitude and frequency content of the vibrations.

Jan 1, 1987

By Bill Bauet, John Anderson

There are always security concerns when explosives are transported and stored, and these concerns are intensified in peacekeeping operations where explosives could fall into the wrong hands. MREL Specialty Explosive Products Limited has developed FIXORTM, a new approach to neutralizing landmines and unexploded ordnance (UXO). The product consists of two precursors: a flammable liquid in one plastic container and a totally inert powder in another; neither of these precursors is classified as explosives. Both precursors are approved for transport by land, sea and commercial passenger airfreight. The precursors are mixed to form an explosive immediately prior to placement next to the UXO or landmine. Initiation is by blasting cap or detonating cord.

Jan 1, 2001

By Dale S. Preece, J Paul Tidman, Stephen H. Chung

A discrete element computer program named DMC_BLAST (Distinct Motion Code) has been under development since 1987 for modeling rock blasting (Preece & Taylor, 1989). This program employs explicit time integration and uses spherical or cylindrical elements that are represented as circles in two dimensions (2-D). DMC_BLAST calculations compare favorably with data from actual bench blasts (Preece et al, 1993).

Jan 1, 1998

By Sam Oaks, David A. Smith

The new Corridor "G" Federal Highway Project in Logan County, West Virginia is the largest mass excavation highway project currently being built in the United States. Seven sections covering 14 miles of four lane highway and two connector roads will require over 30 million cubic yards of excavation. Construction is on a fast track schedule requiring the contractors to complete excavation and pavement placement in a little over 19 months. The two different general contractors have implemented several innovative Blasting and Excavation Programs to complete this project within the tight completion schedule. The paper expands on some of these unique programs that made the project a reality.

Jan 1, 1994

By Chantale Doucet, Yves Lizotte, Alan Cameron

A joint Federal Government-Industry research project on the effect of geology on the fragmentation of rock excavated by blasting in underground developments was conducted at the CANMET Experimental Mine, near Val d'Or, Québec. A total of thirteen (13) blasts were studied from November 1994 to February 1995. The analysis of each blast was divided into three stages: pre-blast characterization, including structural mapping, assessment of Rock Mass Ratings (RMR), Tunneling Quality Indices (Q), blast design documentation; blast characterization comprising blast vibration monitoring and analysis; and post-blast assessment comprising fragmentation assessment by digital photoanalysis, calculation of half cast factors and measurements of bootlegs.

Jan 1, 1996

By Jaki M. Wilson, Neville T. Moxon

The detonation pressure of ANFO can be significantly reduced by the addition of low density materials such as polystyrene, bagasse, sawdust or perlite. Laboratory and field test results have shown that homogeneous mixtures of these low density explosives can be produced in a bowl truck and loaded into a blasthole without segregation. The detonation pressure of the mixture can be altered to be more compatible with the material in which it is being used by varying the quantity of low density additive incorporated into the mixture. Field results have shown that these low density explosives can lead to significant cost savings without compromising fragmentation or production.

Jan 1, 1989

By Richard Scales, Giles Hellyer, Ian Travers, Dean French, Peter Bellairs

"The Mt Whaleback iron ore mine is located in the Hamersley Province situated about 1OOOkm to thenorth of Perth, the capital city of Western Australia. A small but significant portion of the waste in Mt Whaleback presents problems due to its ability to react with normal commercial bulk explosives resulting in premature detonations, two of which occurred at the mine in 1983 causing great consternation as well as disruption to the mining operation. The techniques and procedures developed to overcome this problem were based on the use of tough durable, acid and heat resistant liners to provide a physical barrier separating the explosive from the rock togetherwith the development of an accurate down the hole remote temperature logging technology. The liner technology was developed due to the inability to produce a reliable inhibited ANFO despite exhaustive mine based testwork."

Jan 1, 1999

By Elaine Gorham-Bergeron

CAROM is a distinct element, dynamic code developed at Sandia National Laboratories to calculate the motion of rock fragments during blasting.[1] It has recently been improved to incorporate a mechanism for its elements to mimic non-circular rock fragments. With this option, elements stack and move in ways that are characteristic of irregular boulders of blasted rock. In bench geometry, CAROM has been used to examine the possibility of producing variations in muckpile shape due to variations in detonation-time delays between rows. Surprisingly, the shape of the muckpile was predicted to be insensitive to time delays between detonation of rows of explosive, except where the rock fracturing was affected by the time delays.

Jan 1, 1987

In situ, most Taconite is heavily pre-fractured; because of the high cost of comminution of taconite, maximum fracture of pre-existing blocks is desirable. Sustained borehole pressure plays a significant role in fragmentation, especially by penetrating pre-existing fractures. The distribution of explosive-induced energy in the burden in three dimensions was calculated. Data on the comminution of single particles was used, with the distribution of energies and the distribution of pre-existing block sizes, to calculate fragmentation for a case study. The calculation agreed well with the measured fragmentation. Sequential comminution events are much more efficient than single ones, and enhanced fragmentation may be possible with alternative blasting practices. Some important factors in the dependence of comminution on energy input are discussed.

Jan 1, 1995

By Donald J. Westmaas, Fred C. Drury

The factors affecting the selection and use of exploisves have changed radically in the past three decades. The objective of this paper is to point out considerations which should now be employed by the Explosives Engineer in his selection and use of modern chemical explosives.

Jan 1, 1978

By Geoff Baldwin, Alastair C. Torrance

The use of monitors to assess equipment performance is carried out on a routine basis in many industries. The benefits gained through process control in knowing exactly how the equipment is working far outweigh the initial capital costs of the monitor. In the mining industry several dragline monitors have been developed and installed on equipment through out the world, but to date none has been fully accepted by the industry. This paper describes the use of a sophisticated monitoring system which incorporates an onboard processor to assess both dragline and blast performance. The use of a radio telemetry link for data transfer has removed the need for manual data collection and transfer, leading to a more efficient and powerful system. Significant effort has been put into the development and verification of a dig index to allow blast performance to be objectively assessed.

Jan 1, 1990

By G. R. Adhikari

A major part of mineral production comes from surface mining and there has been a rapid growth in this sector with the deployment of high capacity equipment. The importance of blast design combining appropriately both theoretical methods and practical approach has been well recognized in the field of surface mining. It is known that blast design has a direct consequence on productivity, safety and economic viability of these mines. Blasting is the most common method of breaking rocks in mining, but it has to be cost-effective. In coal production, for instance, drilling and blasting account for 25 percent of the total procution cost. In hard rock mining, the cost of drilling and blasting is about 40 percent. Due to ever increasing concern for cost-effectiveness together with environmental consciousness, designing blasts for each application has now become a stringent requirement and indeed a challenging task as well.

Jan 1, 2002

By Henry P. Van Ormer

This paper is written to outline the capabilities and flexibility of the electric motor driven oil cooled rotary screw air compressor in construction and mining applications. With the changing economics between fuel and electric power all over the world, the viability of the electric motor is a choice all construction and mining people should be aware of. The advent of large efficient electric motor driven rotary screw compressors have given a great deal of flexibility to the use of these units on many applications not considered before. Examples are given for rotary and percussion drilling, fennels, and underground, sandblasting and "uniting, general uses - shows wheel mounted and skid mounted units.

Jan 1, 1976

By Robert E. Miller

Mass blasting of open stopes and pillars is a normal operating practice at Isa Mine. Three main parameters are used to classify the types of mass blasts. These are type of explosive used, blasthole diameter and system of initiation. Both electric and non-electric initiating systems are currently employed. The advantages gained by large firings are many. More efficient utilization of manpower, due to the concentrated and continuous charging, is achieved. There is no requirement for men to re-enter areas where localised ground conditions may have deteriorated and exposure of ringfirers to stope voids is reduced.

Jan 1, 1980

This paper presents a brief discussion of three case histories to illustrate several aspects of the question of blasting in or immediately adjacent to concrete. The results demonstrate a need to make dramatic upward revisions in previous criteria, whether it be the standard particle velocity criteria or damage response spectra bounds, - especially those which include conservative upper limits of constant acceleration for the high-frequency portion of the spectrum. It is demonstrated, also, that conventional off-the-shelf blast-monitoring instruments are not capable of monitoring small blasts at close range. Both the frequencies and the levels of effect are beyond the range of such instruments. These case histories suggest further that there is a need to review the applicability of certain wellknown equations of elasticity.

Jan 1, 1980

By Satish Kate

Mining of Iron Ore in India is done by Surface Mining methods and most of the deposits are massive and are occurring in Hills, surrounded by green forest cover. While majority of iron ore produced are from mechanized mining systems, some quantities are also produced from semimechanised mines. In mechanized mines, apart from state-of-the-art level of mechanization, the Run-off-Mine ore is subjected to multi-stage crushing, screening and washing/beneficiation, for improving the grade and ensure segregating of different size range. The steel plants within the country have been operating their own captive mines, where both lumps and fines are used in their furnaces. In case of mines, which exclusively supply ores to export market, the lumps produced yield very high price and thus efforts are being made to maximize lumps recovery. The mine, where the author had been associated, is an export-oriented mine which supplies iron-ore to Japanese steel plants.

Jan 1, 2004

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

Falls of ground remain a leading cause of fatalities and injuries in underground mines. In response to this situation, the Bureau of Mines conducted a series of experiments in the White Pine room-and-pillar copper mine which resulted in smoother, safer ribs due to a reduction in the amount of overbreak caused by blasting. The tests evaluated the effects of changes in the loading of the rib holes of the mine's 20- by 28-ft drift round driven in shale and sandstone. The relative integrity of the ribs remaining after the blasts was measured using both photographic and seismic refraction techniques.

Jan 1, 1989

By Richard W. Watson, Julius Roth

The Bureau of Mines has recently completed a contract study of the hazards associated with surface mining.! Part of this effort involved an analysis of surface mining accidents associated with blasting activities. For this purpose, 71 reports of accidents investigated by the Bureau of Mines or the Mining Enforcement and Safety Administration (MESA), covering the period from 1962 to 1976, were collected and analyzed. In addition, blasting accident frequencies for the period 1973-1976 were extracted from the central computer files maintained by the Health and Safety Analysis Center (HSAC) in Denver, Colorado. This paper presents a preview of the findings, which are treated in more detail in the final report.

Jan 1, 1978

By Shijie Qu, Paul N. Worsey

Pre-splitting has become widely adopted for the formation and protection of final surface rock excavation profiles in both large scale civil construction and highway rock cuts. Jointing has been shown to affect the success of pre-splitting and the smoothness of the resulting profile, however, only closed joints have been investigated. Frequently jointing that is closed at depth is open at and near the surface due to weathering, reduced stresses and ground water percolation. In many instances, problems are associated with surface rock layers whereas at depth these problems are either reduced or do not exist.

Jan 1, 1987

By Calvin J. Konya

Many controversies and differences of opinion exist in blasting technology. The primer location in small diameter dynamite columns is an example of one of these controversial areas. It is generally agreed that in rotation firing of small diameter blastholes, primer placement near the bottom of the borehole is beneficial since it reduces the likelihood of cutoffs. The controversy results in the actual location of the primer in the bottom of the blasthole. Some references indicate that the primer cartridge should be the first cartridge in the bottom of the hole, with the cap pointed toward the collar of the hole. Others indicate that performance is improved with no sacrifice in safety by placing a tamped cartridge first in the hole, and the second cartridge being the primer. The following investigation provides some factual data for consideration.

Jan 1, 1980