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By Catherine T. Aimone-Martin, Meyers Joseph A.

A new strain-based criteria is being adopted for rock blasting in New York City (NYC). This criteria is based on several years of research involving vibration measurements of tall structures during blasting within several feet from buildings designated historic and Landmarked. This research has demonstrated that tall, heavy structures show little upper-structure vibratory response during hard-rock, urban blasting carried out in NYC. The Fire Department of New York City (FDNY) permits rock blasting and regulated limits for ground vibrations using the U.S. Bureau of Mines (USBM) safe blasting criteria. However, these regulations are often superseded by a 0.5 in/s (12.7 mm/s) limit imposed by the New York City Department of Buildings for historic and Landmarked buildings that are adjacent to the majority of blasting projects in the City. This onerous limit is often exceeded resulting in frequent stop work orders that increase the cost and time of rock excavation projects. The

Jan 1, 2019

By Clarence R. Zink

A problem has always existed in deep and fast drilling situations such as coal overburden drilling, or when drilling with a tight annulus, such as 9 7/8" bits and 8 5/8" pipe. This problem is the difficulty experienced by blasthole bit and blasthole drill rig manufacturers to attain large jumps in bit and drill rig productivity through bit and rig design, when drilling in these specific situations. In other drilling situations, these large jumps in productivity have been easily attained.

Jan 1, 1998

By Jena Moshen

Underground Bulk Systems (UBS) technology has gained widespread application in tunneling and underground mining owing to its safety, reliability, increased Velocity of Detonation (VOD) and excellent results. However, its application in perimeter blasting is still limited and researchers are looking at ways of harnessing this technology for perimeter control. This simplifies the charging process by using one cost efficient product for charging both the perimeter and grid holes. This paper presents a case study on the application of underground bulk emulsion explosives for perimeter control blasting in underground room and pillar platinum mines. In order to achieve the required coupling ratios in the perimeter holes, the emulsion is loaded into specially formulated smaller diameter polyethylene (poly) pipes. The effectiveness of this method was evaluated using information obtained during routine blast audits and data supplied by the mines on half cast factors, over break and under break as well as analysis of data from Ground Penetrating Radar (GPR) Scans over a period of four years. This method of perimeter control, has given the platinum miners in Zimbabwe a competitive edge in cost effective perimeter charging and blasting by simplifying the previously costly deployment of traditional barrels and other decoupled cartridges. The method has been adopted by all the platinum mines in Zimbabwe as it has proven to be a cost effective alternative of controlling the perimeter walls, along with other key benefits that relate to safety, productivity and effectiveness.

Jan 1, 2018

By Randal Martin

Recently, questions regarding the influence of atmospheric temperature and humidity levels on airblast levels have arisen at a number of blast sites. Humidity is alleged to have contributed to high levels of disturbance within communities surrounding blasting. In some cases, local regulatory agencies considered adopting guidelines to specify humidity and temperature ranges under which blasting cannot take place. However, it is normal blasting industry practice not to consider humidity or temperature effects, in the absence of inversions, on airblast levels. When blasting is conducted in the vicinity of residential structures, the influence of weather on the propagation and attenuation of airborne noise from the blasting site is always a concern. Sound naturally attenuates in air with distance from the source. A part of this attenuation is attributed to divergence at the airblast wave front, while the remainder of the attenuation is an accumulation of various factors that include temperature and barometric pressure, absorption in air due precipitation and vegetation, wind and temperature gradients, atmospheric turbulence and topography (Beranek, 1971). Wind speed and wind direction, as well as vertical and horizontal temperature gradients can cause airblasts to focus in local regions surrounding blasting operations and may result in air pressures greater than expected. In fact, wind and temperature inversions can actually increase sound levels with distance from the blast site. Close to the blast site, the effects of inversions may be negligible but may exceed 10 dB at 800 m or greater (Davis and Cornwell, 1991).

Jan 1, 2001

By Robert Hopler

That some time in the year 1872 there was organized an association composed of practically all of the manufacturers of gunpowder and other high explosives in the United States, the members of which said association were as follows: E. I. du Pont de Nemours & Co., The Hazard Powder Company, Laflin & Rand Powder Company, Oriental Powder Mills, American Powder Company, The Miami Powder Company, and Austin Powder Company of Cleveland, all of which or their successors are defendants herein; that the object and purpose of said association was the elimination of all competition between the members thereof in the shipment and sale of gunpowder and other high explosives among the various States and Territories of the United States; that the only manufacturers of gunpowder and other high explosives which did not join such association at the time of its organization were the California Powder Works, The Sycamore Manufacturing Company, and The Lake Superior Powder Company, but your petitioner alleges that each of said three last named companies

Jan 1, 2008

By Michael D. McGill, Jeff Freadrich

There are many factors which affect the productivity of a front end loader. One of the most obvious is the characteristics of the material being mined. Characteristics such as size distribution, swell factor or heave, and material hardness / abrasiveness will all effect the efficiency of the mucking cycle. The focus of this paper is to look specifically at the size distribution of blasted material, and quantify the effects on loader productivity.

Jan 1, 1994

By Jerry Wallace

This project consisted of blasting for expansion of a major interstate natural gas transmission pipeline pump station. The pump station handled 400-500 million cubic feet (1 l- 14 million cubic meters) of gas per day.

Jan 1, 1996

By Douglas Anderson

Even though there is always a feeling of anticipation before a blast is detonated, most blasts are part of a day’s work. Once in a while there is an event that impresses even the most jaded blaster. Few blasts have had the impact of the Kingdome implosion in March of this year. Fortunately for both the Seattle area and the explosives community, the “impact” of the implosion was far less than many local residents had feared. This outcome, of course, was not by chance, but the result of careful planning and design. An urban implosion requires a mix of engineering, logistics, and public relations. Unique challenges on this project tested the resourcefulness of the entire team.

Jan 1, 2001

By Italo Onederra, Jason Furtney, Ewan Sellers

The detonation reactions occurring during rock blasting result in high pressure gas phase products from the condensed explosives typically used in mining applications. After detonation and the initial fracturing, the work done by the expansion of this gas contributes to burden movement and further rock fracturing. Before all of the energy in the reaction product can do useful work on the rock, some of this energy is lost to crushing and possibly to gas venting to the atmosphere. Borehole gas pressure decreases by three principle mechanisms: (i) expansion of the borehole cavity, (ii) flow into the fracture network, and (iii) flow through the stemming. To simplify the problem and to get a better understanding of the interaction of these mechanisms, a simple model for each of these mechanisms is developed. A comparison is made of the time-scales and the influence on burden movement for each. A comparison of gas flow behavior is made between typical ANFO and emulsion products.

Jan 1, 2012

By Ali Kahriman, Alper Celtikc, Serdar Celik, Tuncer Gungor

This paper presents the results of ground vibration measurements carried out in Gülyali Hisarcik Basalt open pit mine located on the north side of the Anatolia near Ordu province in Turkey. Within the scope of this study in order to predict peak particle velocity level for this site, ground vibration components were measured for 5 shots during bench blasting. In blasting operations; ANFO (blasting agent), gelatin dynamite (priming) and delay electric detonators (firing) were used as explosives. Parameters of scaled distance (charge quantity per delay and the distance between the source and the station) were recorded carefully and the ground vibration components were measured for all blast events using 5 different vibration monitors (4 White Mini-Seis and 1 Instantel Minimate Plus Models). The absolute distances between shot points and monitor stations were determined using GPS. The equation of square root scaled distance extensively used in the literature was taken into consideration for the prediction of peak particle velocity.

Jan 1, 2013

By Dave Otto, Ron Elliot, Ed Hatch

This paper is a summary of the work carried out by an international team of specialists in the successful explosive compaction of the sand fill core of the Molikpaq offshore oil production structure. The sand fill core is an essential element for the stability of the structure. The sand core must resist liquefaction forces caused by heavy wave action, ice loading, and earthquakes. Explosive compaction methods were used to improve the stability of 220,000 cubic meters of coarse dredged sand placed in the core area. This project was challenging for a number of reasons. It was performed offshore in Russia, seven kilometers off the East Coast of Sakhalin Island. Logistics were a challenge, not just in getting the men and materials to the site, but also working with restricted headroom inside an operating oil drilling platform. This project called for the use of specialty explosives, strict blast vibration controls requiring a complex sequential blast design, and use of custom designed drill rigs. As Russian equivalent explosives were not available, the project involved getting approval for use of North American explosives in Russia, and use of a combined Russian - Canadian blasting crew. The blasting program was carried out successfully, meeting the required densification target _in a safe, effective manner, with no damage to the structure.

Jan 1, 2000

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

Numerical modelling was used to examine priming of bulk commercial explosives. Data for the HOM equation of state were calculated using a representative chemical composition, while Forest Fire model data were calculated, using a Pop plot which was estimated on the basis of existing sensitivity data, albeit for cap sensitive, small diameter explosives. The length and diameter of the primer, the location of the detonator in the primer and the shape of the primer form a set of parameters which are investigated. The effect of confinement and borehole diameter are also demonstrated, as reflections of shock waves create regions of high pressure in the explosive. The results are presented in terms of pressure and decomposition histories in the explosive and are interpreted in an engineering fashion to form rational suggestions for optimization of the priming process in the field.

Jan 1, 2002

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 Steve Dillingham

Here in the United States, as well as around the world, pose a daily dilemma - to wash or not to wash. Let’s face it, all trucks, especially our industry work horses - bulk trucks - get dirty. We all know that these units can be very expensive and washing them keeps your business investment looking new, improves public relations, fuels company pride, and facilitates equipment safety and preventative maintenance inspections.

Jan 1, 2001

By William G. Szymczak

A set of experiments were conducted at the Aberdeen Proving Grounds [1] in which explosive charges were buried in saturated sand beneath a suspended rigid platform. The goal of these experiments was to measure the dependence of the impulse transmitted to the platform on the standoff distance and the charge burial depth. Simulations of these experiments were performed using the BUB2D axi-symmetric code using a frictional-cohesive visco-plastic model to describe the response of the saturated sand. This code solves a constrained set of conservation laws in which the liquid region (in this case saturated sand) is assumed incompressible. The explosion is initialized as a high pressure gas bubble (void) within the fluid. Comparisons of the simulations to the experiments are presented together with a study of the physical phenomenology associated with the loading process. In particular, it is shown that the force imparted to the platform is a combination of the impact of the sand on top of the explosion gas bubble and the pressure of the bubble as it expands before venting into the atmosphere. Under certain conditions, when the platform standoff is sufficiently small and the platform is sufficiently large, the bubble can over-expand before venting and pull the platform downward. This phenomenon was studied further through carefully measured and photographed small-scale experiments performed at the University of Maryland [2]. The small-scale experiments provide additional important validation benchmarks for our model.

Jan 1, 2005

By Robert B. Hopler

The hazards which naturally prevail in underground coal mines, always severe and unpredictable due to the loosely-consolidated strata in which coal is frequently found, are increased by the commonly-occurring combination of coal dust, methane, and explosives. It was recognized by the mid-nineteenth century that coal dust was the basic factor contributing to disastrous explosions killing hundreds of miners, and that the ignition of methane gas was often the source of the coal dust explosions. It was apparent that preventing the ignition of methane was a critical part of avoiding these disasters, and it was also apparent that one cause of such ignitions was the firing of explosives. In addition, it was found that dust explosions were often initiated by blown-out shots of explosives in the absence of methane.

Jan 1, 1996

By Tom Palangio, Ralph M. Olmstead

Video inspection of boreholes with cameras developed specifically for the mining industry is now possible. These designs are reliable, cost effective, and have the flexibility to be used in other applications.

Jan 1, 1998

By John Heilig, Patrick Andrieux

"Near-field monitoring of blast induced seismic vibrations is a practical and useful way of assessing blast field behaviour for diagnosis and optimization purposes. It is also necessary in order to provide the information from which empirical vibration prediction equations, such as the one proposed by Holmberg (11 for example, can be derived. (Strictly speaking, the “near field” extends from the blasthole itself to about one charge length away from it; however, throughout this article, “near field”will.most often refer to the outer limit of this zone, from roughly 0.75 to 1.50 charge length away.) In order to obtain reliable data, proper field monitoring techniques are of paramount importance. Once the data are properly recorded, analysis can be done either in the time domain (describing vibration amplitude vs. time) or in the frequency domain (usually describing vibration amplitude vs. frequency)."

Jan 1, 1995

By P. O'Connell, J. Lever, C. Clemence

The Bulyanhulu Mine, Tanzania is constantly trialing ideas for improvements in the drill and blast process. The project work has resulted in a large number of choices in explosive type and charging methods being available for blast design. Interestingly, though booster sensitive bulk emulsion had been introduced to the site to reduce dilution, better results were being obtained from reduced charge columns (decoupled columns of poured anfo in 50mm pvc pipe) and pneumatically loaded anfo upholes, which had been traced. In order to compare the explosive type and charge up-methods, an explosives comparison trial was performed.

Jan 1, 2006