Search Documents

By Calvin Konya, Steven S. Spagna, Ed Smith

During Summer 2001, the U.S Army Corps of Engineers awarded a contract to the construction firm of Bush and Burchett of Allen, Kentucky, for the purpose of developing a 13 acre redevelopment site by removing approximately 2.5 million cubic yards of rock (fig. 1). The Redevelopment Site will be the future home for a large portion of the City of Grundy, Virginia. Additional work items include the construction and relocation of 3,000 feet of the Norfolk Southern railroad bed, the placement of 95,000 cubic yards of fill and the placement of 16,000 cubic yards of stone slope protection along the Levisa Fork River. Bush and Burchett received a notice to proceed with construction in July 2001. Currently, the contract is near completion. Current activities include: hauling of material from the Redevelopment Site to the disposal area; placing fill material on the Redevelopment Site, and placing Stone Slope Protection (SSP) along the Levisa Fork river. Approximately one year into the construction highly weathered rock, degraded to near soil- like condition, was encountered in the upstream portion of the excavation. Over one-third of the original cut slope was adjusted and the blasting specifications had to be amended to accommodate for the material that was encountered in this area.

Jan 1, 2005

By Sharkey Bowers

This study was undertaken in order to determine a conservative estimate of the attenuation rate of vibrations through the shallow limestone in South Florida due quarry blasting. The natural limestone bedrock in occurs at or near the surface in southeastern peninsular Florida. While the shallow overburden soils is advantageous for mining purposes, vibrations from blasting has been a contentious issue in South Florida due to the proximity of the mines to several residential communities. White Rock Quarries and Krome Quarries are two active mining facilities in South Florida which generate numerous complaints, insurance claims, and lawsuits from residents in nearby communities who claim that the vibrations cause damage to their houses. Both quarries are located on the eastern edge of the Everglades, with thousands of nearby residences at the western edge of development in Broward and Miami-Dade Counties. Data obtained from over 400 publicly available blast monitoring and associated seismograph reports from White Rock Quarries were reviewed and compiled. The data was used to emperically develop a conservative estimate of the ground attenuation rate based on the scaled distance from the blast origin, which can be compared to Figure B-1 from USBM RI 8507 to determine whether it is feasible if damage could have occurred at a given property.

By Egonk Arriagada, Jair Alarcon

The efficient use of energy in the ore comminution process is an increasingly important strategic issue for improving the productivity and competitiveness in the mining industry as is in recent years the related focus on reducing energy intensity on the atmospheric pollution and greenhouse gas emissions from its use.

Jan 1, 2015

By Roy McKinstry

In March of 2001, Barrick Goldstrike became the first surface gold operation in North America to evaluate the advantages of electronic detonators. A detailed study was conducted to quantify the benefits of the use of electronic detonators to the downstream excavation, crushing and ore processing operations. The following methods were used to quantify blast performance: High speed film and video monitoring Firing time and rock response analysis of the high-speed films Digital fragmentation analysis of the post blast muckpile Vibration waveform analysis (including Fast Fourier Transforms and seed waveform modeling) Excavator performance quantification Crusher, SAG mill and ball mill performance evaluation Ore recovery analysis Cost/benefit analysis

Jan 1, 2002

By Ryan Brogden

On the 5 September 2014 a road train (tractor-trailer) with two trailers carrying ammonium nitrate was involved in a single vehicle accident on the Mitchell Highway, 30 kilometers (18 miles) south of Charleville in Central Queensland, Australia. The ammonium nitrate was being transported to a mine site for use as a blasting explosive. The truck came to rest in the creek bed adjacent to a road bridge and caught fire. The vehicle burnt for over one hour before the load of ammonium nitrate exploded. Miraculously there were no fatalities; however eight people nearby sustained injuries, some seriously. The road and rail bridge over Angellala Creek were destroyed and vehicles in the nearby vicinity were seriously damaged. The truck carrying the ammonium nitrate was completely destroyed with over 2500 pieces of debris scattered up to one thousand yards (one kilometer) from the blast site.

Jan 1, 2018

By Francisco Sena Leite, Thomas Palangio, Vinicius Miranda

With an increasing pressure to find efficiencies in the mining industry, operations are looking for continuous improvement tools to validate blasting procedures, a crucial and often overlooked area of the process. Using case studies completed at both small and large-scale mining operations, this technical paper proposes a practical methodology for pattern expansion studies, taking into account terrain parameters, rock quality and explosive strength. This technical paper will use a series of tools geared towards an economical continuous improvement procedure, using UAV particle size analysis to optimize blasting based on “generalized reduced gradient” for non-linear problems, with cost savings being the main objective. For the validation of this methodology, one scenario was created based on the operation’s budget: an economical continuous improvement plan that relied on manual data collection methods in order to baseline and optimize procedures.

Jan 1, 2018

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 Stephen Chung, John Carpenter, Scott Gosch, James Breedlove

While controlling fly rock and ground vibration in quarrying in the neighborhood of a residential area, producing good fragmentation and keeping different grades of material separated in a muckpile are important in maintaining the productivity of quality aggregates. This paper describes a single row production blast for the study of fragmentation and displacement in the grade control carried out at a quarry of Barrett Paving Materials Inc. in Sylvania, Ohio. Digital video imaging was used to monitor the blast-induced motion of the bench face as input to the DMC_Blast (Distinct Motion Code), for the analysis of the formation of the muckpile. The actual digitized blast video and the DMC_Blast simulation are compared. The displacement and mixing of all the inter-bedded limestone layers are made visible in the simulated cross-section of the muckpile. The apparent fragmentation analysed with PowerSieve is also discussed.

Jan 1, 2001

By J Edmund Hay, Harry C. Verakisl, Richard J. Mainiero, John J. Mulhern

As the first stage in the rulemaking process, MSHA prepared requirements for the approval and use of permissible explosives and blasting items in underground coal mines. These draft requirements known as "preproposals" were announced in the Federal Register in mid-1984. The draft requirements on the use of explosives were written as a revision to Title 30, Code of Federal Regulations, Part 75, Subpart N. The draft requirements for approval of permissible explosives including sheathed explosives for unconfined applications, approval of water stemming bags, approval of detonators and approval of blasting machines were prepared as Parts 15, 16, 17 and 25 respectively.

Jan 1, 1985

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 John Cowin, Dan McCutchen

Cowin & Company has specialized in underground construction since 1924. This paper reviews the sinking of two shafts in the Alabama coal fields using bulk-loaded explosives. Each shaft is eighteen hundred feet deep, and their diameters were twenty feet and twenty-three feet. The first consideration in changing to a new explosives system was safety. Safety began with the explosive supplier training the miners in the use of the new system, from explanation of the pumping unit on the surface to hands-on training in the shaft. The considerations covered include establishing a thunderstorm exit plan, and reducing exposure time of the crew to explosives while loading. The system consisted of a specialized pumping unit and an advance emulsion product. Eliminating the need for nitroglycerin based explosives, and reducing sensitivity to mechanical shock were goals that were met. Performance in the shaft and ease of use meant morale of the miners using the system remained high and positive. Performance benefits discussed include reducing the number of holes in the round, and cutting explosives loading time in half. Damage to the ribs of the shaft was greatly reduced, making it safer to work near the ribs on succeeding rounds. Cleaning the bottom before drilling the next round also showed marked improvement. The economics of the system became very apparent when cycle time saved was allocated against fixed cost of sinking these shafts.

Jan 1, 2000

By David G. Paton

"Electromagnetic surveys were conducted at the BXL Bulk Explosives Limited Mixing Plant andsurrounding area to characterize runoff from the site and possible impacts of salinity. The BXL Plant is located at the edge of a depressional area and any escape of soluble ions, such as nitrates, would have ended up in the slough to the west of the plant. Two electromagnetic (EM) instruments were used in the survey. A Geonics EM 3 1 was used in October 1997 and in June 1998, a new multifrequency instrument, a GSSI GEM 300 was also tested. Both instruments were individually mounted on a plastic sled with Teflon runners and towed with an ATV quad. Position was determined using a Trimble Pro XL global positioning system (GPS) with a real time correction mode Landstar receiver for an accuracy of about *l m. Both GPS and EM instruments were set to collect data at 1 second intervals. The quadrature maps for both instruments showed essentially the same information, namely of very high conductivity, appearing to emanate from the mixing plant. The levels of conductivity were highest where the saline water appeared to pool, at the southern end of the slough. Soil sampling locations were identified from the EM maps and navigated to using the real time GPS. Composite samples were collected by hand using a Dutch auger, from two locations, in increments of O-1 5, 15-30, 30-60 and 60- 90 cm. The analysis of the soil samples indicated a complete absence of nitrate or ammonium ions; the major anion was sulphate, indicating naturally saline subsoil conditions. The GEM 300 made the collection of data more efficient, as only one pass was required to collect the data from four depth intervals. The EM survey combined with the real time GPS allowed rapid characterization of the site with respect to soil salinity and proved to be cost-effective for Phase l/ Phase 2 site assessments and targeting sampling locations."

Jan 1, 1999

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 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 Thad M. Jones

This paper considers the sampling, digitizing and reconstruction of seismic signals. A sampling frequency range is proposed and a minimum limit is suggested. Digitizing precision criteria for both peak velocity and analysis applications are given. Several methods for reconstructing signals from sampled data are presented.

Jan 1, 1985

By Terry Matts, Bruce Ripley, Clark Fletcher, Paul Rapp, Stan Holtby, Jim Dent

The Stave Falls Project of BC Hydro, situated 65km east of Vancouver, BC, Canada, involved the construction of a new two-unit 9OMW hydro-electric facility to replace an existing powerhouse. The final phase of the intake excavation consisted of a plug blast to break the channel through into Stave Lake. The plug consisted of a rock and till wall topped with a fill cofferdam, about 51m wide and between 8 and 12m high. Total rock volume was approximately 2600m3, overlaid with about 4600m3 of till/fill. This paper describes the methodology and practical techniques used in planning and loading the blast, and the precautions taken to protect the new and existing structures and equipment. Blasting of the plug by the normal method using downholes would have required the placing of extra fill and much drilling through casing, so the contractor made the decision to drill horizontal holes from the dry, downstream side. Because of poor rock conditions, all 183 holes had to be drilled oversize at 3.5” dia. and fitted with 2.5” id. plastic pipes to keep them open. Hole lengths ranged from 2.5 to 18rn, with a pattern of 1.5m spacing and l.Om burden (with the holes slightly fanned vertically). Because of significant water exposure, a film-packaged emulsion explosive was used, placed using a pneumatic cartridge loader for maximum borehole compaction. The powder factor averaged 1.3kg/m3 (2.21bs/yd3, rock only). An initiation system of combination surface/downhole delay shocktube units was employed, with double and triple redundancy. The maximum number of holes firing in any 8ms window was limited to three (to minimize vibration), while the whole sequence was fully activated before the first hole fired. All shocktube connections were secured and covered over at the foot of the rockface before flooding the excavation downstream of the plug prior to the shot, To protect the powerhouse gates from hydraulic shock, all hole collars were grouted and an air curtain was provided. The blast was completely successful. A maximum vertical displacement of 6m was recorded, but no flyrock was evident. Readings for peak over-pressure and vibration were well below the allowed limits. Mucking proved to be easy, with fine fragmentation, full pull, and no tights.

Jan 1, 2000

By Lindsay Wade, Peter Dare-Bryan

Benches in surface mines often contain known areas of ore and known areas of waste, which must be mined selectively. When rock is blasted it not only fragments but is also physically, and non-uniformly, moved. Risks therefore exist of ore being lost if treated as waste and of mill feed being diluted by waste. Both possibilities carry serious fmancial implications.

Jan 1, 2001

By Lyall Workman

New mines are frequently located at altitudes above 3,000 meters (10,000 ft.). Drill selection must take the altitude effects into account, to insure high productivity and good bit life. In particular, compressors must be sized differently than for low altitude operation. A larger compressor is required to deliver adequate air to the bottom of the blasthole. Many drills in remote locations use diesel engines as the prime mover. Altitude effects on engine performance should also be considered.

Jan 1, 2007

By David E. Siskind

Increased mineral consumption and environmental concern have caused much interest in potential damage and annoyance from ground vibration and airblast produced by production blasting in surface mines and quarries. Ground vibrations are traditionally blamed for "shaking the house to its foundations," but often the airblast is responsible, particularly when the distances from mine to structure are large. Simultaneous measurements of ground vibrations, structure vibrations, and indoor and outdoor noise from blasting are being used by the Bureau of Mines to determine the relative importance of the ground and airborne blast energy in shaking the structure and making windows, dishes, etc., rattle.

Jan 1, 1977

By Yeon-Ho Jin, Eui-Haeng Heo, Yun-Seok Park, Sung-Oong Choi, Hyung-Dong Min, Min-Su Jeong, Seung-Joong Lee

As rock fragmentation in bench blasting can affect the following process such as loading, hauling and crushing, its good control is essential for assessment of blasting efficiency and production cost.

Jan 1, 2015