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By John Arrell, James Stuart

We have developed a tester that is uniquely able to measure the no-fire power level of certain types of electro explosive devices (EEDs). In the past, it has been difficult to establish a no-fire power level for nonlinear conductors, such as semiconductor-bridge (SCB) EEDs, and conductive-mix EEDs.

Jan 1, 2011

By A. S. Tawadrous

This paper is an evaluation of Artificial Neural Networks (ANN) as a tool in the design of the geometry of surface blast patterns. The built model uses eight different parameters, which affect the design of the pattern. Those parameters are rock type, stratification, blasthole diameter, bench height, type of explosive, priming position, powder factor and fragmentation size required. The network was trained to predict burden and spacing of the blast pattern. The model was built and trained (back-propagation technique) using 43 case histories collected from the literature. The model has then been validated using 16 cases from operational quarries.

Jan 1, 2006

By Dale S. Preece, Ruilin Yang

Shock wave physics is an important part of air-deck behavior since the bulk explosives in the column impart a shock into the air-deck where the air shock then passes through the air-deck at a rapidly attenuating velocity. Through both high-fidelity modeling and shock physics theory it is shown that the resulting pressure in the air-deck is two orders of magnitude less than the detonation pressure of the explosive. The induced air blast reflects from the bottom of the borehole and this reflected pressure, even though doubled, is still approximately two orders of magnitude less than the detonation pressure. Air-shocks will ring back and forth in the air-deck for a few tens of milliseconds while the adjacent explosive column(s) are detonating. Transmission of the initial shock through the air along with reflections is an intensive energy consuming process. Energy balance results in shock heating of the air and a temperature increase. However, the increased temperature of the air is also orders of magnitude less than that of the explosive detonation products immediately behind the detonation front. Replacing high energy explosives with zero energy air-decks in a blasthole will always have a negative impact on the adjacent rock fragmentation and movement.

Jan 1, 2016

By Jhon Silva-Castro, Russell Lamont

Understanding the behavior of materials subjected to high strain rate conditions is of fundamental importance to the mining industry. Several stages of the mining process involve high speed loading rates including blasting, scraping, comminution, etc. Technical comprehension of how rocks deform, fracture, and fail under these loads is a fundamental first step required prior to any serious attempts at optimization of the energy utilized for pertinent activities in the mining process. A Split-Hopkinson Pressure Bar (SHPB) was designed and constructed at the University of Kentucky to study the dynamic properties of various types of rocks.

Jan 1, 2017

By Steven D. Knudsen, Dale S. Preece

The spherical element computer code DMC (Distinct Motion Code) used to model rock motion resulting from blasting has been enhanced to allow routine computer simulations of bench blasting. The enhancements required for bench blast simulation include: 1) modifying the gas flow portion of DMC, 2) adding a new explosive gas equation of state capability, 3) modifying the porosity calculation, and 4) accounting for blastwell spacing parallel to the face.

Jan 1, 1992

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 Kirk Yeager

During the last several years the FBI has been involved with a detailed study of explosives designed to replicate formulations utilized world-wide by terrorists. In addition, numerous formulations , based on literature and internet sources were examined. During the early stages of this work, a good many of the energetic mixtures studied were based on simple ammonium nitrate fertilizer. While the use of ammonium nitrate in commercial explosives is well studied and documented, the characteristics of the mixtures produced by criminals and terrorists have been less well researched. To aid law-enforcement in understanding the properties of these poorly understood formulations, a “cradle to grave” examination of their characteristics was conducted.

Jan 1, 2001

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 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 Kenneth Eltschlager

The Surface Mining Control and Reclamation Act of 1977 requires that blasting be conducted so as to prevent injury to people and damage to public or private property. The three adverse effects are flyrock, ground vibrations and airblast. Blasting close to people frequently results in complaints of annoyance or damage. Federal and State personnel are responsible for evaluating the validity of the complaint. The elements to be evaluated include: reviewing blast logs, inspecting the mine, inspecting the house, measuring ground, air and structure vibrations, and predicting vibration levels. Computer spreadsheets, with their graphical capabilities, will be used to show how data can be cross tabulated to verify data accuracy. Complete statistical analyses of vibrations require more powerful software to make vibration predictions. Once all available data are gathered and verified, a decision on the complaint can be made.

Jan 1, 2001

By M. Oguz Ozkazanc, Gulsev Uyar Aldas

Because of its safety, being easy to handle, relatively inexpensive and containing a lot of energy, ANFO is the most popular and widely used explosive in Turkey as well as other countries in the world. According to change dated May 14th 1999 on the regulation 87/12028 related with explosives, blasters are not allowed to mix ammonium nitrate and fuel oil in the tield to make ANFO. Instead of this, they have been forced to use the ready ANFO prepared by explosive producer firms. As a result of this obligation, the use of technical nitrate for agricultural purpose and mixing AN and fuel oil in unsuitable conditions have been prevented. Indeed, wrong mixture means waste of energy and money.

Jan 1, 2001

By J. P. Remi Proulx, Juan Camilo Gonzalez T., Winston B. Wilches

Alabama USA based Drummond Ltd. operates two open pit mines in the Cesar Coal Basin of Northern Colombia. The mines produce a combined total of over 25 million tons (22.7 Mt) of thermal coal per year which is transported by rail to Puerto Drummond, a direct ship loading facility, where it is exported to over 15 countries. The company has proven and probable reserves in excess of one billion tons of thermal coal.

Jan 1, 2015

By Paul Worsey, Ron Ecklecamp, Scott G. Giltner, Ronnie Inman, Terry Drechsler

A blast monitoring program conducted at Chemical Lie Company’s new lime calcining facility near Ste. Genevieve, Missouri is discussed. The purpose was to develop blasting criteria for the construction and operation of the lime plant within the quarry operated by Tower Rock Stone. Further, it was imperative to accommodate production requirements into the blasting criteria. The major concern was the effect of blasting on the curing of green concrete during the construction of the storage silos and kiln stacks. In addition to discussing the susceptibility of curing concrete to blast vibrations, the paper also details how this varies with time.

Jan 1, 1996

By A. Spathis, I. Yacob, A. Labriola, G. Smith

Wall control is a significant issue for many mines. Improvements to the design process for blasts adjacent to temporary or final walls will require better measurement tools and predictive models. Orica Explosives has developed capability in both these areas and uses them to guide better wall control blasting practices. Vibration and gas pressure were monitored behind a series of production blasts and single hole blasts at the Freeport Grasberg Operations Opencut Mine. The blasts used ANFO in both 3 11 mm and 35 1 mm blastholes in a blast design which reduced the charge weight by between 30 to 50% in the final row of the production blasts. Single hole blast data were obtained by delaying the last hole in the production blast. Vibration levels were within the range often associated with vibration induced damage: 178 to 1080 mm/s at distances between 14-75 metres from the blast.

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 Thomas Kovalchuk, Kenneth Eltschlager, William Shuss

In April of 2000, two adults and their newborn infant, were poisoned by carbon monoxide in their home and received medical treatment at a Pennsylvania hospital. Carboxyhemoglobin levels were; child - 3 1%, father - 28Oh, and mother - 17%. Initially the furnace was blamed but after further review, blasting at a nearby coal mine was determined to be the source. All other sources of carbon monoxide were ruled out. The blasting was about 400 feet from the house. The conditions that led to the migration of gas include: the blasts were highly confined, the geologic structure contained fractures that served as conduits for the carbon monoxide to reach a hand-dug well outside the house, and the well was atmospherically connected to the basement floor drains.

Jan 1, 2001

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 Xue Yongpeng, Zhu Zhenhai, Zhu Ming

The purpose of the Solid Medium Controlled Blasting Technique and Its Applications is to have the inside of the vessel-shaped framework (e.g: oil tank , water pool, gas chamber, chimney, water tower, grain warehouse and etc.) or the one side of the thin wall-shaped structure(e.g: steel bar concrete wall and etc.), both of which are intended to be demolished, inserted with the required solid medium (e.g: soil , sand , coal, salt and etc.) ,in which there is a certain mass density, and then through which the blasting energy is transferred to fulfill the blasting task. For such a technique, it is necessary to bury the explosives into the inserted solid medium and then to start the explosion to blast the intended target into pieces. The filling of the solid medium may be done mechanically or by man. Compared with the water pressure blasting technique, this one has the characteristics of good effect. wide application, simplified construction procedure , safe and reliable operation and small vibration (less vibration than water pressure blasting by 80% to 90%)in particular without any flying stones, thus resulting in better and comprehensive social and economickfficiency.

Jan 1, 2000

By Tapan Goswami

A column of stemming material keeps explosion gases at high pressure for longer times in a blasthole. In general, use of appropriate stemming enables the achievement of the desired level of fragmentation and looseness of muckpiles, as well as the reduction of airblast and fly rock. The ejection resistance of a stemming column varies with the type of stemming material employed. In an effort to optimise stemming at Mt Owen Mine in the Hunter Valley, Australia, a trial was conducted to assess the efficiency of two types of stemming materials. Mt Owen mine relies on through seam blasting and stemming quality is important in this challenging blasting environment. Each type of stemming was trialed in different section of a blast. The blast was designed using Orica’s SurveyPlus@, LoadPlus@ and ShotPlus@ software. Measurement was done using high speed filming of the blast and then post blast information was obtained from analysis of the film. Data analysis included determination of the ejection velocities and percentage swell. Digging rates were measured from excavator production rates. Despite the presence of rounded surfaces and finer particle sizes, River Pebble stemming material showed superior ejection resistance. It also appeared to perform as well as more angular and expensive Crushed Stone, a finished quarry product, based on excavator productivity and heave. It was recommended that future blasts at the mine be stemmed with the River Pebble stemming material.

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