Search Documents

By C. T. Aimone-Martin, V. L. Rosenhaim

Blasting near residential areas has become frequent in many locations throughout Brazil. It was deemed necessary by the authors to have a better understanding of how typical Brazilian structures respond to blast vibrations and compare this response to environmental forces that naturally act on these structures. Typical Brazilian structures are built with clay bricks and cement-mortar. Foundations comprise concrete beam perimeter walls and thin concrete slabs. Roofs are very heavy as they are construction with clay tiles over a wood frame. Typically, walls are cover with cement grout, spackling (or plastered) and then painted. Interior walls are made of clay bricks and mortar to divide in rooms inside the structures.

Jan 1, 2014

By Catherine T. Aimone-Martin, Brent Meins

Blast vibration monitoring for buried pipelines is typically conducted at the ground surface with a shallowly buried geophone. In many jurisdictions across the U.S., blast-related vibration limits set for pipelines are dictated by surface measurements and do not consider the significant reduction of PPV amplitudes acting on the pipe at depth. This study involved a vertical array of geophones deployed in drilled holes at two blasting sites of the Loop 202 South Mountain Freeway construction project in Phoenix, Arizona. City of Phoenix pipeline engineers were concerned that blasting would damage an aged 48-inch (122 cm) prestressed concrete cylinder pipe (PCCP) that serviced water for South Phoenix

Jan 1, 2019

By Braden T. Lusk, Brett C. Jackson

The Kentucky Commissioner of the Department for Natural Resources, accompanied by a motion for accident prevention from Kentucky’s Explosive Industry and other associated fields, have requested for an Industry Flyrock Prevention Task Force to be formed by an Explosive Industry panel. This task force is led by Dr. Braden Lusk at the University of Kentucky. The mission of this task force is not only to identify the base causes of flyrock incidents based on analyzing historical data from events in the past, but also to track the advancement of flyrock elimination into the future.

Jan 1, 2014

By R Frank' Mammele Chiappetta, Conny Postupack

A major problem that has continued to plague the surface coal industry is blast induced damage to the coal seam. Atlas Powder Company has addressed this situation through seven years of field research in full-scale production environments. Many operations across the United States have been evaluated.

Jan 1, 1988

By L. A. Heim, E. A. McCullough, N. J. Amiotte

The explosives industry is subject to the laws of multiple jurisdictions, which means that several regulatory agencies are responsible for governing different aspects of the commercial explosives industry. Among these regulators are the Mine Safety and Health Administration (MSHA) who implements codes that better ensure both occupational and public safety which is influenced by professional blasting projects and the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF), who enforces commercial explosives storage and security, among other responsibilities.

Jan 1, 2014

By Victor Munoz, Jorge Oliva, Gonzalo Marias

Cerro Vanguardia is a known gold and silver deposit located in the province of Santa Cruz, Argentina. The mine has been in operation since 1998 and is thought to be one of the most important mines in Patagonia. More than 102 epithermal quartz veins have been identified in the area, with variable lengths, thicknesses, orientations and dips that constitute what is possibly one of the most extensive outcropping vein systems on earth.

Jan 1, 2019

By Martin Schrier

This paper is an overview of a granite quarry cleanup near Kirkland Lake, Ontario, Canada. A combination of local geology and previous subpar blasting techniques led to the quarry needing significant rehabilitation before it could proceed with general operation. Advanced technologies were implemented into the blasting process, including laser profiling, bore-hole tracking, and geometric timing. The contract consisted of two floor shots and two 25,000 tonne (27,558 US ton) production shots.

Jan 1, 2018

By Tom Watts

Bulk Security Best Practices

Jan 1, 2006

By Benedict C. Di Duca

In the underground construction industry. when bidding work, not only is the contractor faced with determining if rock: is in existence within the parameters of his work. he must also estimate the quantity and the most efficient method of removal.

Jan 1, 1990

By Steve Collinsworth

Sometimes, for those of us in the right place at the right time with the right product, necessity creates opportunity. Such is my case at a West Virginia coal mine where a mine manager was desperately seeking a way to eliminate coal damage on cast shots while maintaining cast percentage without the expensive process of secondary drilling. This paper will focus on how bottom hole air decking is solving the problem.

Jan 1, 2000

By Luiz Felipe Mendonça de Amorim, Adimir Fernando Rezende, Gustavo Sampaio Lopes, Claudio Cesar Gajardo Arraño, Eltton de Sousa Veras, Manuel Villalobos Calderon

Many technical challenges were encountered while conducting near-field construction blasting between the critical intersection of Interstate 10 and multiple active railroad tracks in El Paso, Texas, for the Loop 375 Border West Expressway Project. Blasting was utilized for the removal of an andesite bedrock ridge in preparation for the construction of a new elevated super structure to be suspended over the existing railroad tracks. There was concern that the excessive vibrations and/or permanent rock deformation produced from the blasting within near proximity (20 feet, or 6.09 meters) of the railroad tracks would induce excessive stress and foul the tracks by shifting the alignment. This could result in a major loss of scheduling control between the two major railroad companies that operate in this area. There was also concern that the blasting may cause rock fragments to land on and interfere with critical interstate transportation. Blasts

Jan 1, 2019

By Francis Otuonye

Rock fragmentation by blasting still remains the most common and cost-effective method of excavating hard rock in mining and tunneling operations. During blasting, the dynamic stresses induced by the detonation of the explosive, in addition to fragmenting the rock in the vicinity of the blast, may fracture the rock at considerable distances from the point of detonation of the explosive. The fractures can result in reduced mine safety, increased costs to support the opening, low productivity and perhaps high ore dilution. Besides the dynamic stresses produced in the rock, air blast overpressure pulses are generated and propagate through the network of underground mine openings. The waves, unable to spread out spherically or hemispherically like blast waves from surface blasting, are forced to propagate by reflection from the roof, ribs and floor down the drift. Blast wave focusing can occur and produce intense shock waves that could damage ventilation barriers such as cement block stoppings.

Jan 1, 1992

By Claude R. Ayoub, Charles A. Kliche, David G. McDowall

Homestake Mining Company's Open Cut Mine is located in Lead, South Dakota, in the northern Black Hills. The mine is within 300 feet of occupied residences on the south end, and within 1200 feet on the north end. Mining began at the north end of the open pit in October, 1983, and blasting related complaints began almost immediately. Noise and ground movement comprised the majority of the structural damage claims. As a result of these complaints, Homestake purchased a recording seismograph and began monitoring nearly every blast. In addition, the company hired a consultant to review Homestake's blasting and monitoring practices. He was also asked to do a single, one-time study of the cracks in six homes. This initial work led to Homestake monitoring all blasts with three seismographs and having South Dakota School of Mines and Technology do a year-long study of crack development and propagation in five homes in Lead.

Jan 1, 1989

By Alastair Torrance, Braden T. Lusk, MinGi Seo, Gary Cavanough

Velocity of Detonation (VOD) is the most commonly used method to determine explosive performance as VOD is a function of the confinement (ground conditions) density and composition of the explosive. Techniques used to measure VOD include resistance wire, time domain reflectometry, simple start stop and fibre optic methods. All these approaches require a cable of some sort to be inserted into each blast hole being monitored and the holes to be fired in a specific sequence. It is time consuming and fairly technical to position the cables correctly to gather the data from each hole. It slows down the hole loading process and increases the number of people on a bench at that time. The equipment and cable limits the measurements to a few holes, typically 5 or less, that are in close proximity. These measurements can generate useful information about the monitored holes but does not provide a full picture of how the explosive is performing across the whole blast and whether any change in performance is noted with changing ground conditions or confinement.

Jan 1, 2019

By Dan McCutchen, Oettmeier

Kelly bar drilling and blasting is unique to Florida, the' Bahamas and other marine limestone areas in the world where blast holes are required but will not remain open for the loading of explosives. This type of rock formation usually yields 1.5 tons of recoverable rock compared to 2.2 tons per cubic yard for competent limestone. The loss of .7 tons per cubic yard is due to voids and sand in the formation. These deposits all contain water to the top of the blast holes which are collared only a few ft. above the ground water level. The working pit is a water filled lake which is excavated from the bank by draglines. These drills have been used in Florida for many years to depths of 65 ft or less.

Jan 1, 1991

By Paul Worsey, Matthew Coy

In the blasting industry, many different techniques are used to estimate and examine the effects of varying explosives and blast designs on the breakage of a rock mass. The overall objective is to find a cost-minimized blasting solution that also conforms to the legal and environmental concerns related to blasting. A major drawback to current blasting methods is the inability to account for "caprock," or a thick overlying layer found in sedimentary rocks that creates large amounts of oversize blasted material, especially on the top of a muck pile. This can lead to underestimating oversize in shots with massive top layers. A better fundamental understanding of blasting processes with caprock is required.

Jan 1, 2018

By Scott Scovira, Ruilin Yang

This paper presents a non-waveform blast vibration model for the near-fi eld. The model uses the concept of a dominant charge augmented by other contributing charges estimated using a scaled time window. The model accounts for the effect of broken ground created by earlier fi ring holes, amplitude attenuation, effects of signal broadening with travel distance from frequency attenuation, as well as asynchronous propagation of different wave types due to the wave velocity difference, the delay time effect, and non-linear superposition of near-fi eld vibration. The model uses an effective distance defi ned from the broken ground screening, and determines a dominant charge contributing to the PPV at a monitoring station. Then the model uses a time window for each individual charge to determine if it contributes to the PPV. The time window has a variable width to model the effects of the signal broadening with travel distance. For modeling the signal broadening, a generalized rock quality factor Qd is proposed. The time window includes a weighting function that diminishes the contribution for charges fi ring further from the dominant charge and this accounts for contribution arising from the timing difference between a contributing charge and the dominant charge. The model uses a non-linear charge weight superposition technique that scales the charge weights within the time window to the same distance of the dominant charge and superimposes the scaled charge weight. The case study demonstrates that the model provides useful predictions for near-fi eld blast vibrations.

Jan 1, 2008

By Philemon Desrochers, Ken Qian Liu

Following the success of the West Ore Zone distress mass blast in 2001 at Brunswick Mine, a similar approach was taken to distress the North Regional Pillar (NRP) which contained over 3 million tonnes of high grade ore. The NRP is located on the 1000 m Level with very poor hanging-wall (H/W) rock mass qualities. After an extensive geotechnical review, the distress slot is located close to the foot-wall (F/W) of the NRP in order to have the competent ore as H/W. The longitudinal area to distress covers 115 m along the strike and 85 m high from 1000 1-sub to 850 Sill. Prior to the final mass blast, 3 voids were created to allow rock swelling: the North void, the South void and the trench just below the mass blast. After over one year of preparation, the mass blast of 202,000 tonnes was successfully initiated on February 7, 2003 with 1561 electronic detonators and 210,000 kg of emulsion explosives. The blast achieved its objective of distressing the NRP as indicated the mine-wide micro-seismic monitoring system. This paper describes different stages of the project from void preparation to the mass blast itself, as well as some detailed aspects such as muck-pile prediction for mucking sequence with the help of DMC_Blast simulation code and electronic detonators.

Jan 1, 2004

By J. Fresnillo, M. Lopez Cano, S. Burgada, P. Couceiro, A. Jafa

This paper explores the sustainable use of the explosive’s energy for rock blasting and its role on the performance of downstream unit operations in mining applications. Since energy efficiency is becoming important for long term mining strategies, cost-effective optimization strategies are required to increase productivity and revenue while minimizing environmental impact. These optimization strategies involve continuous ability to model and measure all related phenomena and operational performance, integrated under a continuous improvement program where all involved counterparts act in close coordination. Although mining is complex, it can be regarded as a set of interconnected processes, where energy is consumed in a sequence, following all unit operations from the pit to the concentration. In this sense, the performance of downstream operations is potentially influenced by the initial energy input, since the explosive is the source of all energy used for rock fragmentation and heave. In this line, sustainable energy blasting is recognized as one of the main strategies for mine energy optimization projects. Finally, a special case study from an important gold mine in South America is presented, where benefits of a sustainable blasting energy strategies has been proved to deliver important downstream benefits.

Jan 1, 2019

By Thomas L. Barkley

My historic auditing of Underground Drilling and Blasting Practices has demonstrated to the author the need for reviews of many mines' procedures in these processes. Poor understanding of the basic principles and practices of the drilling and blasting science in Underground Development Mining has created significant costs to mining operations in many instances.

Jan 1, 2019