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By Deane Boddorff

A 440 Volt AC power line is a typical power source for energizing electric blasting cap circuits in driving hard rock tunnels. A common misconception exists that the caps actually see 440 Volts. This paper describes an analysis of the entire blasting circuit determining the current flowing and the voltage drops through each component. If, from such an analysis, one determines that the current to the caps is too low or too high, the components that require changing are easily recognized.

Jan 1, 1975

By W C. Brukle

Our title for this presentation could be taken in many ways. One course would be terrifying and that would be to cite incredibly bad practices. All of our votes/efforts should be for the reverse direction in which everyone does his/her best to keep their pit or working place free from hazards.

Jan 1, 1983

By G. C. Naveen

Punatsangchu Hydroelectric Project Authority is constructing 1020 MW underground hydroelectric project in Bhutan. The project envisages construction of concrete dam, Desilting Chamber, Head Race Tunnel, Power House Complex and Tail Race Tunnel. Tunneling is one of the major activity in any underground projects as they are driven for multiple activities. By and large the tunnels are a major part of connecting networks from surface to caverns/underground working sites. Many tunnels in hydropower project are part of water conducting systems and one such important tunnel is the Tail Race Tunnel in this project and had to be excavated in thinly foliated rockmass conditions by D&B method. The rockmass is traversed by three to four joint sets and few minor shear seams. Rock Class “Q” values were between III and IV. Tunnel was excavated by full face parallel hole drilling blasting method. The adopted blasting method consisted of drilling 45mm (1.77 inch) diameter holes to a depth of 2m and the drilled holes were charged with 40mm (1.57 inch) diameter cartridge explosives and charges were initiated with half second non electric initiators. The perimeter holes were drilled at closer spacing of 30cm (1 feet) and alternate holes were charged using 32mm (1.23 inch) diameter cartridges explosive. Low dipping foliation joints present in the rockmass tend to slab in crown portion and erratic occurrence of intrusive bodies lead to unpredictable behavior of rock mass posing a major challenge for the safe excavation. Stability was a major issue through controlled blasting under constant supervision too could not limit the overbreak in certain weak rockmass conditions thereby exposing cavities of about 2.5m (8.2 feet). The stabilization of these cavities and handling the overbreak due to rockmass condition was time consuming and warranted additional supports. With systematic measurements and controlled blast designs the Horse Shoe Shaped Tail Race Tunnel of 9.1 m (29.85 feet) diameter and 304m (997.37 feet) length to connect with Downstream Surge Gallery of 314m (1030 feet) length, 18m (59 feet) wide and 58.8m (193 feet) height in thinly foliated and jointed biotite gneiss rockmass was successfully excavated.

By Pat McLaughlin

Blast design in the construction industry has often been based on past practice or powder factors. This is to some extent understandable, since construction projects do not have the longevity of mining or quarrying operations and therefore have less opportunity to pursue potential improvements. The main concern of the operator is whether or not the technique will work, and at what cost to the downstream processes. Time, not long term savings, is of the essence.

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, 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 Shulin Nie, Mats Olsson

The mechanism of rock fracture by explosive is a fundamental in rock blasting. It is generally believed that the shock waves from the detonation initiate the fractures. Then the detonation gases penetrate into the fractures and elongate them. However, our previous researches indicated that the detonation gases do not contribute significantly to the fracture propagation. In our latest experiment, blasts have been carried out in 8 large granite blocks. The main goal was to study the fracture mechanism, namely to determine whether the shock waves or the detonation gases fracture the rock.

Jan 1, 2001

By D E. Shaw, J B. Case, J Gusek

Explosive casting of overburden is defined as the use of explosives in blasting to move overburden to a spoil pile without rehandling. Studies of the economic feasibility of the method, and the formulation of a design hypothesis involving rock properties, and blasthole geometry are presented. These studies indicate that if technical feasibility can be demonstrated to increase surface coal production, considerable economic advantage would accrue to coal mine operators.

Jan 1, 1980

By Shulin Nie

The dead-pressing phenomenon in emulsion explosives is wellknown. Research work on this subject has been carried out at the Swedish Detonic Research Foundation for the last few years. Several experiments with emulsion explosives under dynamic pressure condition have been carried out both in iron pipes and in blast holes in rock. The main object was to study the critical amplitude and duration of the pressure causing the explosive to be dead-pressed.

Jan 1, 1993

By Greg J. Stach, Norman "Skip" Hale

The authors describe the development of an overburden blast casting program in the upper seam of coal at a 2-seam surface mining operation on property adjacent to an active operating underground coal mine. Control of vibration is essential.

Jan 1, 1984

By Malcolm Mellor

Practical procedures that have been developed for pre-split blasting and smooth blasting in common rocks are reviewed systematically. Topics covered include shothole spacing, charge weight per unit length of shothole, decoupling ratio, adjustments for explosive type and rock type, and weight of explosive per unit face area. Relevant properties of frozen rocks, frozen soils, and ice are compared with those of common unfrozen rocks, and appropriate adjustment of blast design is discussed. Interim relationships for the design of controlled perimeter blasting in frozen soils and massive ice are put forward, recognizing that additional experimentation is required. Special problems in controlled blasting of ice are discussed. These include effects of wet holes, delayed removal of burden, and submerged burden. Special attention is given to the cutting of ice islands and icebergs. An Appendix describes an operation in which the face of an ice wharf at McMurdo Sound was trimmed by pre-split blasting.

Jan 1, 1976

AQUILA Mining Systems Ltd., designs, develops and delivers systems for measurement, analysis, simulation, control and automation to the mining, construction and petroleum industries. The objective of current efforts by AQUILA is the continued development and refinement of computerbased systems and techniques to automatically process monitored performance data from surface blasthole drills and mining shovels, and the management and coordination of these pieces of equipment by GPS (Global Positioning Systems).

Jan 1, 1994

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 A. Pope

I have attended two Explosives Engineers’ Conferences in the past 4 years. The first was in Brighton, England with the European Federation of Explosives Engineers in 2005 and the International Society of Explosives Engineers in New Orleans, USA in 2008. At both of these conferences I listened to papers presented on European and English training methodologies and ideologies. As I have been training Shotfirers for the past 18 years in Queensland and the Northern Territory for some 8 years previously, I would like to present our methods of training in Queensland, which I believe is among the best in the world. In Queensland, this training is carried out by a training organisation that is registered by the Department of Education, Training and the Arts under the guidelines of the Australian Quality Training Framework (AQTF). Not only is this Registered Training Organisation (RTO) required to operate under these very comprehensive guidelines, but also those designated by the Explosives Inspectorate of the Queensland Department of Mines and Energy.

Jan 1, 2009

By Mark William Withey

"Blasting safety in surface mining is a necessary industrial goal. Proper techniques and disciplinesexercised during the blasting process enhance the probability of achieving that goal.The blasting process is generally a series of repetitive steps performed by all blasting technicians.Because habits formed during this process influence safety, production and cost, proper habitsbecome compulsory."

Jan 1, 1995

By D K. Joyce

Large diameter boreholes have become increasingly popular in underground mining. Drilling equipment can drill full rings, including vertical upholes. Special techniques are required to load upholes of three inch to eight inch diameter. The current methods for loading AN/FO and bulk or packaged emulsions are described.

Jan 1, 1988

By Donald E. Rossow

In the mining industry ANFO continues to be the primary source of explosive energy. The three most commonly used loading methods are bulk, pour in 50 lb. multiwall bags and cylindrical shaped wet hole bags. Each loading method has its advantages. Each method has certain disadvantages which limit its effectiveness. The expandable bag system developed by ECONEX overcomes the disadvantages of the traditional bulk, pour in bags and wet hole package products.

Jan 1, 1985

By Mark Bauckman

Discussion Topics • Market Needs • Technology Developments & Best Practices • Industry & Government Developments • Future Possibilities & Your Role

Jan 1, 2006

By Sandor Nagy

The Explosive and Blasting Department of the Hungarian Mining Research Institute is responsible for the research and development of industrial applications of explosives. Appropriate explosives technology is developed for each application, including the explosive demolition of structures, which belongs within our charge.

Jan 1, 1977

By Sushil Bhandari

Presented here is the simplified process of fragmentation of homogeneous rocks by blasting based on experimental studies. Small scale single hole blasting experiments on jointed limestone are described. Results show that directions of joints overshadow the degree of fragmentation and also influence the remaining rock. The possible influence of joints on the process of fragmentation of non-homogeneous rock by blasting is also discussed.

Jan 1, 1983

By R. Narendrula, S. P. Singh

The productivity of a loading machine is affected by several factors. One of the most significant is the characteristic of the muck being loaded. A study was conducted to examine the effects of the looseness, angle of repose, size distribution and moisture content of the blasted material on the efficiency of the loading machine. The study was conducted in the following stages: (a) controlled experiments in the lab, (b) tests with loader simulator and (c) field work in an operating mine. It was found that looseness (%void) in the muck increases with the increase in the value of the mean particle size and index of uniformity of the fragmented rock. Looseness and angle of repose affect the fill factor and the digging cycle time of a loader and in turn the productivity of the equipment. Moisture content affects the angle of repose as well as the stickiness of the material to the loader’s bucket. It was observed that the angle of repose increased with the increase in the mean particle size and the moisture content of the muck. It was also found that the bucket full factor and rate of scooping decrease with the increase in the values of mean particle size and index of uniformity. This was also conformed during fieldwork that bucket fill factor decreases with the increase in the mean particle size as well as the index of uniformity.

Jan 1, 2005