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By Jennifer Paukula, Steven Lindsay, S. Joon Kim

String loading is the placement of a bead or ‘string’ of emulsion along the lower edge of a development drill hole. The loading hose extraction rate controls the amount of emulsion placed in each drill hole. This allows a controlled distribution of explosive energy throughout the development round. Center holes are loaded using the slowest extraction rate causing the majority of the explosive energy to be placed in the center of the round. The loading hose is extracted successively faster for the buffer and perimeter holes causing less explosive energy to be placed near the edge of the blast. This causes less damage to the rock mass that remains in place after the development blast.

Jan 1, 2012

By J J. F Smith

The application of pneumatically loaded ANFO for underground mining has continued to increase year by year since the technique was first developed and introduced underground during the early 1960's. Improvements in the manufacturing process for explosives grade prills, the design and construction of more efficient AN prill-fuel oil blending equipment, and the introduction of more durable and reliable pneumatic loaders have promoted the wide application of the relatively low cost blasting agent, ANFO.

Jan 1, 1982

By John P. Ashby

Production blasting is a process of destruction of rock masses in order that ore may be extracted. Many open pit operations are faced with the apparently conflicting requirements of providing large quantities of fragmented rock for the processing plant and of minimizing the amount of damage inflicted upon the surrounding pit slopes. A reasonable compromise between these two conflicting demands may often be found by means of simple engineering of production blasts.

Jan 1, 1980

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 N L. Thomas

Hole size affects many factors which directly influence fragmentation in the muckpile and hence, the cost effectiveness of the entire operation. These factors include production capability, explosives and accessories efficiency and usage and drilling accuracy. In addition, hole size should be chosen to suit the geological conditions. The paper concludes that the optimum hole size is generally the largest that can be used commensurate with production and environmental considerations.

Jan 1, 1986

By Selwyn Pearton

Pumpable emulsion explosives have been available to surface and underground massive mining operations for decades and through their unique properties offer significant advantages through improved safety, reliability and performance. Despite their advantageous properties, the benefits of pumpable emulsions have been unavailable to narrow reef mining operations due to the void in technology necessary for their successful implementation within the challenging environment. Despite efforts to promote and enhance the safety and performance of bulk emulsions for narrow reef stoping, little research has been undertaken to advance the pump technologies required for their implementation. This has resulted in a gap in knowledge and technology and as a consequence the successful implementation of a pumpable emulsion system has consistently eluded the narrow reef environment.

Jan 1, 2015

By D O. Tan Sky

This paper will describe the mechanisms involved in delay blasting and how they are applied with the use of D.S.B. It will examine the control of potential damage resulting from detonations, and show how good fragmentation and efficient recovery of this material blasted can be achieved.

Jan 1, 1980

By Michael A. Peltier, Dennis V. D'Andreal, Larry R. Fletcher

Accident data obtained from the Mine Safety and Health Administration (MSHA) were analyzed by the Bureau of Mines to determine the most frequent causes of blasting accidents in U.S. mining and to examine trends in blasting accidents. This accident analysis is an update of a similar blasting accident study conducted by the Bureau and published in 1983. The analysis shows that there has been a recent reduction in mine blasting accidents: The annual average number of nonfatal injuries has decreased from 107 for 1978-81 to 46 for 1982-85. The annual average number of fatal injuries was reduced from 11.3 to 5.0 during that time.

Jan 1, 1987

By Dale Preece, Vanessa Berg

This paper presents a two-pronged vulnerability analysis approach for treating minimally reinforced concrete (RC) structures subjected to explosive events. This work was motivated by a heightened interest in homeland protection involving both malevolent and accidental explosions and the need for assessment of critical facilities subjected to an explosive detonation. The first part of the analysis approach employs the commercial 3-D Eulerian-Lagrangian hydro-code AUTODYN, while the second part of the analysis employs Single-Degree-of-Freedom (SDOF) methods, each predicting the dynamic response of the minimally RC walls, slabs and columns to explosive loading. The concrete is treated with the newly developed RHT (Riedel, Hiermaier, Thoma) constitutive model, which accounts for failure mechanisms in brittle materials. Predictions from AUTODYN are verified using the equivalent SDOF reinforced concrete code, SPAn32, developed by the US Army Corp of Engineers and agreement between the results indicates a high level of accuracy in both methods of analysis, allowing for accurate predications of airblast-structure interactions and failure mechanisms.

Jan 1, 2004

By J T. Schamaun

Recent applications of explosives and blasting agents to rubble rock have led to requirements for more elaborate design and analysis methods. In most blasting uses, it is necessary not only to fracture the rock, but also to move the broken rubble in a predictable manner. Many in situ extraction techniques require; rubblization to take place in a confined region where rock motion is a predominate factor in creating a permeable broken bed. In this paper, an engineering model is presented which describes the large rubble motion during blasting. This model is intended to provide the blast designer with a tool for evaluation and further refinement of blasting patterns and timing sequences.

Jan 1, 1983

By Frank Hirthammer

Over the past few years, development and implementation of digital logistics solutions has convinced users of many additional advantages of this technology. Barcode labeling and reading increases the company’s efficiency and safety by reducing handwritten documentation and preventing misinformation. Sustainable information and productivity management is a significant advantage in competition. Since manufacturing information is tracked throughout the whole supply chain until the final consumer, all processes become transparent what ensures efficient risk tracking, correct disclosure to authorities (if required), and the compliance with company rules.

Jan 1, 2018

By Andrew F. McKown

Overbreak and damage to rock walls at the perimeter of rock excavation can lead to safety problems due to rock falls and additional costs due to a] extra mucking, b] extra concrete or shotcrete to backfill overbreak, c] additional rock reinforcement, d] additional water inflow and e] additional maintenance of rock walls. To minimize these undesirable effects, there are several perimeter control techniques available (i.e. line drilling, cushion blasting, pre-splitting, smooth blasting, and fracture control blasting) which control perimeter hole spacing, burden and loading to provide a smooth, stable excavation contour. Conventional perimeter control loading and hole spacing is satisfactory for massive, homogeneous formations, but when blasting in weathered or fractured rock closer spacing and very light loading is required.

Jan 1, 1984

By R R. Singh, U K. Dey, S K. Roy

"Commercial explosives being a heterogeneous mixture of many chemical compounds in prefixed proportion, their velocity of detonation (VOD) may vary from batch to batch, due to variations in the proportion of the chemical composition and process parameters even within their tolerance limits. Inherent limitations of measuring methods and human variations during measurement also add to the variation in VOD values determined practically. Therefore, it is customary to define a range of VOD values rather than a fixed value of VOD for a particular explosive.Variations in VOD values of four commercial permitted explosives in India were evaluated under open unconfined condition using Dautriche method and a resistance wire method based continuous VOD meter. Comparative evaluation of VOD values of selected explosives were aimed to check the relative effectiveness of continuous VOD measurement of small diameter cartridged permitted explosives using cheaper co-axial wire instead of recommended costly VOD rods along with the continuous VOD meter. Results of evaluation revealed that continuous VOD of commercial small diameter cartridged explosives could be determined using cheaper co-axial resistance cable with comparatively better accuracy than the most commonly used Dautriche method."

Jan 1, 2007

By Marcia Harris, Richard Mainiero

The New York State Department of Transportation recently commenced highway widening and drainage improvement projects in Clarence and Amherst, NY. Drainage improvements including the installation of storm sewer lines required excavation to a depth of 2.5 m (8.2 ft). In September 2002, NYSDOT stopped further blasting when 800 ppm CO was detected in the basement of a house near the blasting site. At the insistence of NYSDOT, the general contractor developed a new blast plan with the assistance of an environmental consultant. The plan provided for the installation of multi-gas monitors in buildings of special concern and/or with basements and residential type CO monitors in all other buildings within 100m (330 ft) of the blast. The multi-gas monitors would be remotely monitored. The plan provided action levels which would ensure public safety. The blast design was also modified to allow for better venting of CO. Blasts were limited to 20 ft lengths. The overburden was to be removed from the rock and blasting mats put in place to prevent flyrock. Approximately twenty feet of trench adjacent to the blast was left open to allow ground movement and gas release. The use of CO monitors was effective to alert occupants of a building to the presence of CO. The most effective appeared to be the residential type CO alarms with digital readouts. They were simple and easy to use and allowed the public to participate in the process. False alarms were repeatedly received with the more sophisticated instrumentation. Residential type CO monitors are preferable to warn people near blast sites. More sophisticated instrumentation should be avoided unless personnel are experienced in its use. A general overview of the blasting and monitoring is presented and discussed. The use and effectiveness of residential type CO monitors and multi-gas monitors are discussed.

Jan 1, 2004

By Jeff Gore, Jack Dermody, David Gribble, Brett Macaulay, Bart Sharpe, Paul Klaric, Paul Thornley, Ben DeVries

Optimal Fragmentation in Block Caving is difficult to achieve as it is generally defined by the rock mass itself and the way in which the cave is initiated. The lower portion of the cave has even less chance as the material has little time for self comminution. Blast Preconditioning of the Block Cave is designed to engineer the lower section of the rock mass to produce material of a suitable size to assist in the initial cave propagation and improve initial drawbell productivity. At Cadia East a plan was developed to drill 150-metre long, vertical up-holes from the undercut level and blast them fully confined to produce fractures in the rock mass. The blast itself was a simple undertaking. However, in the year preceding the first production blast, all aspects of the process were designed, tested and refined across multiple trials. As this type of challenging application had not previously been encountered in Australia there were many unique situations to address. Products and systems had to be developed and adapted to overcome these challenges. These included: Formulating and manufacturing an explosive that is robust and of a high VoD; designing and manufacturing easy to use electronic initiation systems; and, designing pumping systems to combat high head pressures to allow for successful and safe loading of the holes. Close collaboration with the customer ensured that the trials culminated in successfully blasting a hole containing almost 3.3t of explosive. These trials have since led to the blasting of four holes instantaneously, which contain almost 13t of explosive. This paper describes the various components of the system, the challenges and the final result.

Jan 1, 2013

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 Ryan Redyke, Jared Redyke

The demolition of an old power plant boiler house in Parsons, Kansas calls for the use of some linear shaped charges. The steel is thick and the structure is heavy but gravity can be a blaster’s best friend. This entry did not win in a very competitive category. We thought it was worthy of coverage in the Journal of Explosives Engineering.

Jan 1, 2015

By Robert Slivinski, Kyle Hobbs, Michael Stern, John Willox, Brad Jewson

Prairie Mines & Royalty Ltd. produces over 12 million tonnes annually of thermal coal for TransAlta’s Sundance and Keephills power stations from the Highvale Mine. This opencast mine is next to a lake and is surrounded by cottages and farms, which means that blast vibrations and air overpressure have to be kept to a minimum.

Jan 1, 2008

By R R. Dimock

A goal of all mine operators is to optimize the breakage of the inplace rock to achieve maximum excavating efficiency. The use of the seismograph at Kennecott Copper Corporation's Nevada Mines Division, open pit mine in Ely, Nevada, has demonstrated that optimum blastability can be predicted by knowing the seismic velocity of the inplace rock. The relationship of seismic velocity to the quantity of the explosive required to achieve adequate breakage of the material can be determined. Once quantified, this relationship can be used by the mine operator to obtain the optimum drill pattern and powder factor for breaking the material to be excavated. A substantial savings in primary and secondary drilling and blasting costs can result from using the seismograph for blastability determination.

Jan 1, 1976

By Zheng Deming, Li Hongwei, Lei Zhan, Dai Chunyang

This paper introduces the application of a digital electronic detonator in the demolition blasting of largescale (LS) and long delay time (LDT) frame-shear structure buildings. The whole building to be demolished by blasting is an L-shaped frame shearing structure. Some parts of these buildings have a large length along the direction of collapse, so the detonation delay of the column is longer. To ensure the building is successfully blasted and demolished, a digital electronic detonator detonation system is adopted. In the design of the detonating network, full use is made of these characteristics of the digital electronic detonator, such as flexible installation, high precision of delay before blast, and dedicated testing equipment to check the reliability of the network. These advantages ensure the damage of the load-bearing structure is within the blasting gap and that the accuracy of the collapse time of the building, which not only guarantees the collapse effect of the building, but also provides strong technical support for improving the intrinsic safety of the blasting operation and the supervision of the flow direction of the detonation, these research be provide reference for the application of digital electronic detonators in similar projects.

Jan 1, 2019