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By Pierre Mousset-Jones, Jaak Daemen, Songlin Zhang, Jon Hurley

Most western United States open pit gold mine ore bodies are disseminated deposits. The mineralization is so irregular that it is difficult to visually identify the ore/waste boundary. Blast hole samples are used to interpolate digging polygons based on the pre-blast position of the bench. Dilution caused by blasting is of major concern at these mines, since blast movement can mix and dilute the ore and move it beyond flagged digging polygons established on the blasted rock according to their pre-blast location. Typically, mines try to reach a compromise between blast fragmentation and movement.

Jan 1, 1994

By A. K. Sirveiya

A major concern with blasting at surface mines is generation of ground vibration, air blast, flyrock, dust & fume and their impact on nearby structures and environment. A study was conducted at a coal mine in India which produces 10 million tonne of coal and 27 million cubic meter of overburden per annum. Draglines and shovels with dumpers carry out the removal of overburden. Detonation of 100 tonnes of explosives in a blasting round is a common practice of the mine. These large sized blasts often led to complaints from the nearby inhabitants regarding ground vibrations and their affects on their houses.

Jan 1, 2005

By Shad M. Sargand, Glenn A. Hazen, A M. M Jayasuriya

Various types of waves originate from a blast source to propagate through rock/soil media away from the blast. Input vibration to a structure depends on the soil-structure interaction which varies with the dynamic properties at the intersection as well as the stress and strain levels developed from the vibration of the structure-ground system. Hence it is important to study such effects on the response of a structure due to blast loads and this knowledge can be used in the design and control of blasts that are carried out close to buildings, highways and other structures.

Jan 1, 1994

By Calvin J. Konya

There have been many different brands of high precision caps introduced on the US market in the last five years. High precision timing definitely effects the performance of the blast. One should be able to optimize fragmentation and minimize environmental effects with the use of high precision caps and selection of the proper time period. The consumer who purchases the caps may not be fully aware of the tolerances in firing times of caps used in the field. This paper will discuss results of field tests of cap tolerances from an independent study conducted by Precision Blasting Services.

Jan 1, 1989

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 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 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, Quebec. 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 Terry Graf, Bill Thompson, John Guenther

SYNCRUDE CANADA LTD.. operates the largest synthetic crude oil production facility in the world. Over 60,000,000 Bank Cubic Metres of oil sand is mined each year from their open pit located in Fort McMurray, Alberta. Despite the extremely cold temperatures encountered during the winter months and the problems associated with frost buildup, SYNCRUDE has continued to operate on a 12 month per year basis. In 1989 SYNCRUDE mine management embarked on a comprehensive Frost Blasting program to improve mine production of their oil sand moving equipment. The following paper will discuss the development of their frost blasting program to its current status.

Jan 1, 1993

By William R. Adamson, Carlos R. Scherpenisse

The successful development of surface mining operations depends, amongst other factors, on the successful creation of final pit walls which offer long term structural stability. The achievement of such walls will be much more feasible if the mechanisms of rock mass deterioration in the mine are well understood, permitting the control and reduction of this deterioration (or damage). The role of drilling and blasting in causing damage is widely accepted but rarely fully quantified. It is also true that the dependence of rock mass damage on vibration levels is only incompletely understood and little accurate field measurement is routinely conducted in the mining industry.

Jan 1, 1998

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 Keith L. Bockelman

The Colowyo mine is a unique surface coal mining operation because it is a multiple seam pit. Using a combination of a shovel-truck and dragline operation, Colowyo mines 8 seams of coal to a depth of 400 ft. Over the past 3 years a number of operational changes have occurred, one of which is the implementation of blast casting. Through this implementation Colowyo has been able to eliminate over one million cubic yards a year, which would have had to be removed by the shovel-truck operation. This has also brought about a significant decrease in the stripping cost per ton within the dragline operation.

Jan 1, 1985

By Francis O. Otuonye

A time series and system analysis modeling technique was applied to signals from strain egages mounted on a fully grouted resin roof bolt and signals from accelerometers mounted on the bolt head and roof rock to determine the roof bolt's response to repeated blast loading. The derived model gives a comprehensive quantitative description of the modes of vibration of the roof bolt response to each blast loading. The damping ratios and natural frequencies of the modes of vibration can reveal the alteration of the process dynamics due to the deterioration of the roof rock and can be used to identify the incipience of instability in the roof bolt system.

Jan 1, 1987

By Zuhair Ibrahim, Dan Tillema, Ali Reza

This paper details the investigation of a fatal explosion that occurred on April 8, 2011 at a magazine used to store fireworks in Waikele, HI. The fireworks had been confiscated by the Bureau of Immigrations and Customs Enforcement after they were informed that a container shipped to the United States contained illegal fireworks. Four groups of cardboard cartons that were marked as 1.4G (consumer fireworks) were determined to be consistent with the more explosive 1.3G type, commercial display fireworks. The subcontractor retained to destroy these fireworks stored the shipment in the subject magazine and was in the process of disassembling them on the day the explosion occurred.

Jan 1, 2014

By D T. Froedge

Before this study was started, literature was searched and cases of alleged water well damage were investigated. Occurrence of ground water in Appalachia is primarily in low yield, fractured, water table aquifers. Four test sites were chosen based on geographic and geologic diversity. Test wells were drilled at each site and base line data on water quality, static water level, and drawdown characteristics were obtained before surface mining commenced. Blast-induced ground vibrations were measured at the surface by the wells at levels up to 5.44 inches per second maximum resultant particle velocity. Measurements made at the bottom of wells indicated that vibrations were considerably attenuated at depths of 140 to 160 feet.

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 J. Sigler

A series of small scale tests have been performed to establish the effect of powder factor and initiation timing on the grindability of rocks. The blasts were performed in high quality granite blocks, which were cut from stone prepared by dimensional stone quarry operations. Three different types of granite were tested. The charge configurations included detonating cord placed in five holes with water as a coupling medium or concentrated charges of equal mass, placed in the same number of holes, fully stemmed or air decked. The powder factor was varied from 0.4 to 1.2 kg/m3. Typically all charges were detonated simultaneously; however, in some experiments, detonation waves collided in the middle of each borehole and in others a small delay was used between charges. All fragments were collected and screened, and drop weight impact tests were performed on selected size fractions, using different impact energy, to calculate the resistance of the rock to impact breakage. The work index of some of the blasted samples was measured using a standard Bond mill arrangement. The experiments generally showed increased softening of the rock with powder factor, which appeared to be the dominant factor. Charge configuration as well as in-hole collisions of detonation waves affected the initial fragmentation but had little effect on the impact breakage of the samples.

Jan 1, 2008

By W. Jiao, Y. Yongqi, R. Shan

Soft rock mines are distributed through out P.R.C. And drilling and blasting is still the main method of driving a tunnel in these mines. Traditional smooth blasting has been widely and deeply studied and put into practice in P.C.R since 1970s. But the cartridge and blast hole are both columns, the stress field in the rock around blast hole at the beginning is symmetry around hole axis, and the original cracks in the rock can be activated randomly. So serious overbreak and underbreak at the boundary of an excavation occur often, especially when the excavation is in soft rockmass, and the rates of half-hole marks are generally about 50% in medium rock, and 20-30% in soft rock in Chinese coal mines. For the sake of overcoming the situation, we have been studying directed crack blasting since ten years, and have got some obvious achievements in this respect. Slotted cartridge control blasting in soft rock is studied in this paper. Through model experiments, reasonable decouple coefficient range and slot width are gotten, and unsymmetrical dynamic strain field is analyzed. Through underground test in soft rock with a strength lower than 1OMpa in Dayan Mining Bureau, The results of which the rates of half-hole marks and the nonsmooth grades of the cut contours are 83.3% and 1OOmm respectively have been achieved.

Jan 1, 2000

By Jerry R. Wallace

A systematic, team approach to pre-blast and on-going problem solving contributed to the successful completion of this indoor industrial construction blasting project.

Jan 1, 1995

By John W. Kopp, David E. Siskind

Over 4 billion pounds of commercial explosives are used by the U.S. mining industry every year with an excellent and improving safety record. However, accidents involving explosives are seldom minor. They produce a disproportionate amount of fatalities compared to other mining activities, as reflected in the relatively high severity rates. The U.S. Bureau of Mines (USBM) has been analyzing blasting accident data obtained from the Mine Safety and Health Administration (MSHA) to determine the most frequent causes of mine blasting accidents, examining trends in these accidents, and identifying areas of needed research. This paper is an update of three previous blasting accident studies conducted on 4-year intervals by the USBM and published in 1983, 1987, and 1991, and is based on a total of 869 blasting accidents.

Jan 1, 1995

By Richard Dooley

The purpose of this paper is to give a description of a controlled blasting program and why Georgia Power now has one; mainly because of the Spillway Project.

Jan 1, 1981