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By D. Bartley, R. McClure, W. Reisz

Ever since the 8ms criterion was developed in the early 60’s there has been an ongoing debate among many blasters as to its actual value in controlling ground vibration. The perpetuation of the myth surrounding the 8ms window can be partly attributed to its simplicity and convenience as a means for regulatory compliance. Unfortunately, the mindset that many blasters have adopted has hindered the development and use of more effective techniques and in many cases can actually be counter productive to vibration control.

Jan 1, 2006

By Michael S. Wieland

The stress waves generated during delay blasting in underground or surface mines not only fracture the surrounding coal, rock, or other strata, but also impact delayed charges remaining in neighboring boreholes. This crossing wave interaction is a ubiquitous fundamental damage mechanism, ultimately responsible for numerous occurrences of misfires and flyrock. The hazards and waste from wave-induced malfunctions are Just the recognized tip of the iceberg. Undetected marginal performance of damaged delay detonators and desensitized charges poses a tremendous unresolved problem, resulting in the reduction of mining profits and the certain retention of unwanted risks.

Jan 1, 1988

Many North American coal strip operations are practicing trajectory control blasting with good results, often based on trial and error methods. This study summarizes the basic technical requirements for the design of bench-type casting with explosives to achieve further improvements.

Jan 1, 1987

By B. K. Rath

The Industrialization of a country depends on its mining activities to a great extent. In mineral production, India has a top rank not only in South Asia, at the global level too. Quantum of mineral production is almost directly proportional to the quantum of explosive production. Mining sector consume more than 80% of country’s explosive production. Due to rapid growth of mining activities in the country, the explosives industry has been developing very fast in terms of quantity, quality and types. , In this paper, India’s post independent chronological date regarding use of explosives, their types, their constraints and a profile of well-known manufacturers has been meticulously presented. A production figure for three years with system analysis has been presented. The paper also deals with present consumption pattern while making a futuristic forecast. In view of the anticipated changes that are to take place in mining industries in near future, the manufacturers of explosives have to pay a vital role. The paper highlights some concrete and valuable suggestions and recommendations. Small scale Companies have to limit their production to Slurry and Emulsion types of Cartridged explosives whereas the large manufacturing units have to concentrate on Bulk explosives, specialized explosives and better initiating systems. The large manufacturing units have also to make all concerted efforts to compete with global market for significant export. The Country for its rapid growth needs basic raw materials like Coal, Iron Ore and Limestone. So, the extraction of these minerals is of prime importance. The more we produce and consume, the more will be Industrialization. The Industrial growth rate has been around 6% during the last few years. As the Industrial growth rate is moderate, there is moderate increase in mineral extraction in the Country. Additional mineral extraction demands additional explosive production (Annexure-1).

Jan 1, 2000

By TA Louw, Dr CM Lownds

In an era where profits are constantly being eroded, mines are looking towards technology developments to assist them in solving mining problems and reducing mining costs. An emerging technology that could assist mines in becoming more cost effective is electronic detonators. Electronic detonators have been under development for several years. Over the past three years, the spotlight has fallen on commercial use of electronic detonators and the extent to which the promise of precise and programmable timing can assist mines with their environmental and productivity problems. This paper uses case studies to demonstrate both surface and underground applications where electronic detonators and blasting systems were used to solve typical mining problems such as vibration and fragmentation. Safety aspects such as hanging wall conditions and high wall stability also benefited from the use of electronic detonators. The paper also demonstrates how the use of accurate electronic detonators and blasting systems has resulted in improved/more even fragmentation with further downstream efficiencies. These efficiencies may include increased cast percentages, reduced oversized rocks, quicker cleaning times and increased production rates.

Jan 1, 2004

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 Michael S. Wieland, Thomas C. Ruhe

Delay blasting in underground coal results in shock waves traveling through the coal that can damage delay charges remaining in the blast pattern. Undetonated explosives which are dynamically desensitized or react sympathetically from shock wave impact ruin blast results. Such malfunctions, sometimes manifest as misfires, more frequently are covert weak detonations, and result in poor coal breakage and fumes with above normal toxicity. To reduce these mining hazards and resolve charge performance problems, the Bureau of Mines has developed and tested forty prototype rugged explosives in the laboratory. Rugged explosives work properly under difficult circumstances because they not only retain their shock initiation sensitivity but also are resistant to shock damage. This research investigation resulted in one candidate emulsion explosive, formulation #37, which passed all the permissibility tests required by MSHA approval regulations. However, approval was not granted because it reached shelf-life (would not shoot properly) seven months into testing. For research purposes, the remaining tests were conducted with a second batch of formulation #37. This paper discusses the prototype rugged explosive composition and permissibility test results. Where possible, for reference purposes, comparisons are made to a commercial product that has been approved. Further research work is required to overcome the noted deficiency of short shelf-life.

Jan 1, 1992

By Thomas E. Lobb, Harry C. Verakis

Significant progress has been made in the reduction of serious injuries and fatalities resulting from mine blasting operations. Despite the progress, injuries and fatalities continue to occur. A leading cause of injuries and fatalities from blasting continues to be inadequate blast area security. Even though significant improvements in technology have been made, insuring adequate blast area security remains a challenge and requires constant vigilance. The advances in technology have created safer blasting products and have improved productivity and economics by enabling large, more efficient and effective blasts. However, as blasts grow larger in size, the complexity of adequately securing the blast area increases even more. Periodically the basic fundamentals involved in blasting safety should be reviewed, particularly for securing a blast site regardless of the size of the planned blast. Factors such as flyrock and toxic fumes must be taken into account to insure the safety of persons and property from the results of a blast. This paper examines the factors related to injuries due to inadequate blasting shelters and blast area security, and identifies mitigation techniques. The key concepts are: (a) accurate determination of the bounds of the blast area, (b) clearing employees from the blast area, (c) effective access control, (d) use of adequate blasting shelters, (e) efficient communications, and (f) training. Fundamentals are reviewed with an emphasis on analyzing task elements and identifying root causes for selected blasting accidents. Mitigating techniques are presented along with discussions and examples.

Jan 1, 2005

By R. Wharton, M. Bagley

Following a series of papers relating to the certification of explosives for sale in member states of the European Union presented at previous ISEE conferences, this poster paper has been prepared to stimulate discussion and debate on the recently published European Directive on Pyrotechnic Articles.

Jan 1, 2008

By Robert L. Brooks

This paper is intended for companies at all levels of the Explosive Industry and in particular, those that do not have a risk manager. It is strictly informational in nature and no reference is made, or intended towards any existing insurance company or agency.

Jan 1, 1993

Vibrations are of concern not only for the safety of surface structures but also for the stability of underground openings. A number of parameters affect the intensity of vibration in underground openings due to blasting in adjacent opencast mine viz. total explosive weight detonated in a round, maximum explosive weight per delay, propagating media, depth of cover, RMR of the roof rock, age of the underground openings etc. Although a few researchers have tried to study the impact of parameters stated above, the impact of initiation sequences on generation of vibration in underground openings due to opencast blasting has yet remained untouched. A study was planned to evaluate the impact of initiation sequences on the magnitude of vibration in underground openings due to blasting in opencast mine. Nine production blasts with top and bottom initiations were performed at Samleshwari opencast project in India and eighteen vibration data were monitored in the roof of Hingir Rampur underground colliery in both the initiation sequences. The result indicated that the vibration produced in the underground openings from bottom initiation was lower than that of top initiation.

Jan 1, 2003

By David Siskind, Mark Stagg

Vibrations from Dade County (Miami area) quarry blasting and structure responses were measured at 11 locations between February and April, 2000, and 10 homes were inspected to analyze the characteristics of their cracking and other damages. These results were combined with information collected by the County and other studies done in south Florida for a blasting impact assessment specific to this area. In addition over 40 quarry blasts in the nine-week monitoring period, about 800 measurements were available from previous monitoring in Dade and neighboring Broward counties. An overall worst-case analyses based on the highest individual amplitudes suggested that vibrations in some areas could have been as high as 0.35 in/s. While amplitudes in the study period were below this value, they were found to be relatively high for the distances and charge sizes. Attenuation with distance is less in Dade County than found elsewhere with quarries having to use scaled distances several times higher than similar sites in the north. Consequently, the vibrations are perceptible at very large distances.

Jan 1, 2001

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 William F. Skully

An effective explosives storage program involves selection of a storage site, checking zoning and special permit requirements, acquisition of the storage site land, determining correct layout for required storage units, selection of storage units, construction of storage area, obtaining licenses and permits, and storage site operation.

Jan 1, 1976

By N H. Maerz

The digital image analysis program WipFrag has been developed under contract to INCO for use in quality control of underground blasting operations. This paper outlines the relevance of fragmentation to underground mining, the hardware and photography requirements, and key features and operating principles of the software.

Jan 1, 1995

By Judy Konya Bowles, Calvin J. Konya

Blast vibration and air blast are commonly blamed for damages to residential as well as commercial structures. Mining and construction companies are often required to spend monies in court defending themselves even when vibration and air blast levels have been monitored by seismographs and are extremely low.

Jan 1, 1992

By S. P. Singh, Turgut Yalcin

The physical characteristics of blasted rock are fundamental variables affecting the economics of mining operations and are in fact the basis for evaluating the quality of a blast. A study was designed with the objective of quantifying the effect of muck size distribution on scooping operations in a mine.

Jan 1, 2002

By Sharon K. Reamer, Yvan Sifre, Klaus-Gunter Hinzen

"Three case studies are presented that illustrate the successful application of firing timeoptimization (hybrid modeling) in the quarry environment and for a construction site. In allcases, the method requires the measurement of at least one in situ, single hole explosion asa representative model of the desired blast design."

Jan 1, 1993

By R M. Bhatawdekar, A I. Theresraj, H S. Venkatesh

Wadi Limestone Quarry is one of the largest captive mines of Associated Cement Companies Ltd, India. The mine management wanted to extend the excavation as close to the plant as possible for maximum exploitation of the deposit. The National Institute of Rock Mechanics and the management of Wadi Limestone Quarry carried out comprehensive investigations to evolve a methodology to control vibration and flyrock within safe limits.

Jan 1, 1999

By Qingshou Chen, Paul N. Worsey

It has been recently argued that rock strength has little effect on the final results of pre-split blasting and is of only minor importance when blasting rock in general. However, it can be shown that the maximum borehole separation for optimal perimeter blasting results with constant borehole and loading configuration is strongly dependent on the tensile strength of the rock.

Jan 1, 1986