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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 Seung-Kyu Baek, Chang-Ha Ryu, Yang-Kyun Kim

Safety concern is one of the most important parameters in the design of building demolition by explosive blasting. Accidents were sometimes reported due to the flying chips of fragmented materials in building demolition work in urban area. Laboratory experiments were performed to investigate the failure behavior of reinforced concrete pillars under blast loading and to develop an effective protection technique. Sixteen reinforced concrete pillars were constructed with two sizes: 450×450×1800 mm and 600×300×1800 mm. The failure behavior and the flying chip velocities were observed by means of a high-speed camera. Protection scheme was designed and the effects of several protection materials were investigated. Two kinds of non-woven fabrics and wire net were tested as protection materials. The results showed that reinforcing bar was one of the important factors to determine specific charges, and that mesh size of wire net and tied-up method affected the protection of flying chips. Control of gas effects is also a key to the control of flying chips. It was recommended to use both wire net and nonwoven fabrics as primary and secondary protection materials. Such protection scheme was successfully applied to the explosive demolition of 16 and 17-story apartment buildings.

Jan 1, 2002

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 Mohammed Alkazimi, Katie Grantham

The purpose of this paper is to quantify the risk to both the environment and surrounding infrastructure from a pipe sealing implosion. Both accuracy and the precision in determining how a submerged infrastructure damaged by underwater explosions performs provide better decision-making capabilities for managers facing impending oil spills. This determination is vital, especially for both emergency and crisis management teams, as categorized consequences based on both the nature of the structural layout and the surrounding marine environment assist in identifying whether or not the utilization of this technique is applicable. Thus, the decision maker’s aim, in a crisis, is to minimize any associated risk that might result in aggravating the situation by endangering both the infrastructure and marine life. Therefore, the resulting risk matrices will enable technical personnel who are not experts in explosive technologies to be armed with the information necessary to determine if this mitigation technique is applicable to their situation.

Jan 1, 2013

By Robert Hopler

On June 13, 1912, the final decree of dissolution of the DuPont explosives trust was handed down, and the resulting new companies began operating at the beginning of the new year. The property assets granted to (or retained by) the companies were as follows:

Jan 1, 2014

By Jair Koppe

The unsatisfactory blasting effect is mainly related to the improper selection of design parameters of drilling and blasting scheme. In order to evaluate the rationality of drilling and blasting scheme, scientifically, this paper brings forward a method for scientific evaluation of blasting scheme. This method evaluates the blasting scheme by observing the accuracy of drilling, explosive density, charge, lumpiness analysis, filling length, slope surface design, floor level, vibration monitoring and flyrock. The evaluation involves different stages of blasting construction and implementation, such as terrain survey, drilling, charging, environmental impact and safety evaluation. Through this method, several key problems for improving blasting scheme design can be determined by analyzing each parameter. This method improves the key parameters of blasting design by analyzing blasting results and establishes the relationship between blasting effect and technical design.

Feb 6, 2023

By O Omidi

Selection of delay times to optimize fragmentation has been a controversial topic among researchers and blasting practitioners. This paper reviews previous experimental information and presents the results of new tests conducted in small blocks constructed using a commercial grout. The effect of the delay on the average fragment size, coarse fragmentation and uniformity of fragmentation is discussed. Fragmentation was coarser at extremely short or extremely long delays, while a fairly constant average size was obtained at a variety of intermediate delays. Uniformity, defined as the slope of the fragmentation distribution through the average fragment size, was poor at short and very long delays and relatively constant at the intermediate delays. Some tests attempted to minimize the effect of gas penetration by lining the boreholes with copper tubes. When this was the case average fragmentation changed marginally, while uniformity was significantly affected by delay and was typically smaller than in the unlined tests.

Jan 1, 2014

By Ruilin Yang

This paper provides a theoretical analysis of shockwaves in an air-deck induced by detonation of an explosive charge and shows that the initial shock pressure in the air-deck at the interface with the explosive charge is only about 1% of the detonation pressure. A rarefaction wave with the low pressure travels back into the explosion detonation products greatly reducing the post-CJ detonation pressure. Additionally, AUTODYN modelling shows that the pressure attenuates further during shockwave propagation along the air-deck. Although the pressure increases at the bottom of the blasthole due to shock reflection, the overall pressure in an air-deck does not increase and is still around 1% of the detonation pressure which is too low to break most rock.

Jan 1, 2016

By Lon Santis, Michael Swisdak, John Tatom

The Institute of Makers of Explosives (IME) and A-P-T Research, Inc. (APT) have developed a quantitative risk assessment tool called IMESAFR (IME Safety Analysis for Risk) for managing risk from various activities undertaken in the commercial explosives industry. The first version was completed in 2006 and Version 2.0 of the software was completed in 2012, incorporating several major new features. The platform is now based on a Geographic Information System (GIS), providing a bird’s-eye-view to help visualize facility layouts and risk. Spatial data on potential explosion sites and exposed sites can now be automatically transferred from the images to ease users’ data input. Use of GIS data provides the ability to check facility compliance with quantity-distance (QD) standards such as the American Table of Distances (used by the Bureau of Alcohol, Tobacco, Firearms and Explosives, ATF), the NATO standard (used by Natural Resources Canada and other nations), or a user-defined table. Research conducted and knowledge gained over the last 10 years enabled changes in the algorithms and models that provide greater fidelity and reduce conservatism. Expert users can change global settings to more accurately match actual site conditions and the program runs using either Imperial (English) or SI (metric) units of measure. These changes and other new features are discussed and demonstrated.

Jan 1, 2013

By D J. McLane, J T. Rathbun, B T. Lusk

The dynamics of explosive detonations are understood, however recreating a real-world, full scale scenario is costly. The use of a shock-tunnel allows testing to be done on a smaller scale, with the simulated effect of a large explosion. Analyzing explosive waveforms using this method can greatly reduce cost in testing blast resistant products, such as anti-terrorism devices, mine safety products, and military equipment. The purpose of this paper is to better the understanding of how the waveform characteristics resulting from an explosive detonated within a shock-tunnel differ from those in an open-air arena test. The variables of comparison between an open-air arena test and those conducted within a shock tunnel are peak pressure, impulse, shock wave velocity, and cross sectional shape of the shock front. Understanding how these variables differ, tests utilizing a shock tunnel can be conducted with a higher degree of accuracy and repeatability.

Jan 1, 2013

By Karl Peterson, Bibhu Mohanty, Chanakya Nariseti

The mechanism of crack formation in two target rocks (Kuru granite and Flamboro Limestone) is studied experimentally by simulating the impact action of a percussive drilling bit. Rock samples are dynamically loaded using a custom made impacting bit (8 mm, 12 mm and 15 mm diameter bits). The target rocks are impacted at velocities 8, 10, and 12 m/s. The resulting crack patterns are visualized by three techniques, Dye penetration, CAT scans and Optical scans. Mapping of the crack patterns is manually done with Photoshop. For 3D damage visualization, the crack patterns are mapped in two planes (impact surface and longitudinal sections). The three techniques are compared to determine an optimum technique for better damage visualization. The evolution of crack pattern with impact velocity and bit diameter is discussed.

Jan 1, 2015

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 Charles E. Van Barneveld

RBH Note: the following item is a little different than the usual, in that it shows how explosives were used in the past to assist in putting down holes for iron ore prospecting on the early Mesabi Range of Minnesota. The way explosives were used would not even occur to the modern explorationist, given the equipment available today. The reason for the great difficulty in putting down a hole was that the area was covered with debris from the great glaciers of the past (the same ones that carved out the Great lakes). This debris consisted of boulders, clay, sand, and any other imaginable mixture of materials.

Jan 1, 2013

By Robert Hopler

THE KEYSTONE NATIONAL POWDER COMPANY is an Independent organization, incorporated under the laws of the State of Pennsylvania. It has three dynamite mills near Emporium, Pa., with a daily capacity of 165,000 pounds. It maintains branch offices in practically all the largest cities east of the Rocky Mountains, and has distributing magazines located in every section where there is a demand for high explosives, with facilities for wagon deliveries. Our mills are all of modern type and are equipped with the most improved machinery for the manufacture of high explosives. The efficiency of our laboratory in conjunction with the high class of labor employed, has enabled us to put on the market an explosive, the quality of which is the result of extensive research and scientific knowledge. Our modern and complete equipment for harbor and railroad transportation insures our patrons of prompt deliveries, which is an essential feature particularly to contractors and those whose facilities for storage are limited.

Jan 1, 2013

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 Doss Brittain

The term ground breaking is taken to include the process of so loosening the ground as to enable it to be readily loaded into buckets or cars and hoisted from the shaft or drift. In the Joplin district are encountered two varieties of ground, the hard and the soft. Hard ground consists of massively bedded rock requiring heavy blasting to loosen it. Such ground is to be found throughout the district in the same localities as the soft ground but more extensively, even to the exclusion of the appearance of soft ground in the sheet formation in the vicinity of Webb City. The Yellow Dog Mine at Webb City and the Grace mine on the Granby land at Joplin furnish well known examples of hardground mining which has become the most extensive in the district.

Jan 1, 2008

By Carlos Enrique Arroyo Ortiz, Jadir Pedro Alves

This paper presents some of the results obtained during the research work about the use of technologies and digital transformation in the process of rock drilling in open pit mines. The use of automation presents itself as a disruptive factor and a driver of improvements that provide sustainability in rock drilling. Seven main operational parameters were utilized to combine measurement while the drilling (MWD) with other information generated by the equipment during hole drilling, in six different lithologies in an iron mine, located in the central region of Minas Gerais in Brazil. Adjustments and corrections were made to the data collected in order to minimize external influences other than the rock itself, to ensure the effectiveness of the analyses. Finally, we sought to compare the performance of the drilling process in manual and automatic operation modes. Thus, making it possible to show the efficiency and impact on the sustainability of rock drilling operations in open pit mines.

Feb 6, 2023

By Christodoulos Xiouris, Ali Reza, James Karnesky

A rocket parachute signal flare is often used to signal a maritime emergency. In the general operation of these devices, a solid rocket motor propels a metal body to an altitude of approximately 1000 ft(305m).At the end of the rocket motor, a propelling charge drives a signal flare and parachute out of the metal body and ignites the flare, which then burns for approximately 40 seconds as it falls to earth. In this paper, we describe an engineering investigation of an accidental ignition of a rocket parachute signal flare, which caused injury to the user. The components of the flare involved in the accident were inspected via x-ray and microscopic imaging techniques, and compared with those of unfired flares recovered from the same vessel. Chemical analysis of residue on recovered components from the accident flare was also performed. These comparisons were used to determine the likelihood that the actuation mechanism had been deliberately manipulated. In the subject model of the flare, ignition of the rocket motor is accomplished through a percussion cap which is struck by a firing pin. Prior to activation, the firing pin holds down a pre-compressed spring. We present a comparison of the ignition system of the incident flare with those of other rocket parachute flares, which do not incorporate any stored mechanical energy.

By L. Chaves

In rock blasting, due to numerous factors, both controllable and uncontrollable, the execution rarely meets the planning. The powder factor is an important KPI for blasting since it represents the amount of explosive used to fragment the rock, therefore it depends on the rock mass characteristics and may be influenced by factors such as weathering and drilling quality. The blasts at the Serra Sul mine, S11D project, are usually big blasts and the high productivity is a challenge for maintaining the quality of the whole drill and blast process. It is important to know the contributions of each of the most common influencing factors of the powder factor to direct the efforts to the improvement of the process. A buildup model is presented to evaluate the contributions of five influencing factors to evaluate the planed x executed powder factor. The factors considered in the model are the average hole depth, the amount of hole/blasted volume, the stemming and decking length, the linear charge weight, and the density of the explosive used. The build-up may be applied for both individual blasts and for overall view of the blasts in a period. A case study is presented with the application of the model for the monthly powder factor analysis at Serra Sul mine has contributed to direct efforts to enhance drilling quality and preservation of the drilled holes.

Jan 1, 2024

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