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By Des Bolton

With the introduction of Cast Blasting techniques, field controls of Drilling & Blasting operations became more important. New drills were purchased which were equipped with sophisticated instrumentation and more accurate drilling plans were required. Concurrently a decision had to be made on the replacement of borehole logging equipment owned by the mine. The use of a contractor to log blast boreholes was eventually decided upon, the information gained from this operation is used in the short-term drill and blast planning and may also be used to assist in the coaling operation if density I quality correlations prove acceptable.

Jan 1, 1994

By Bill Williamson, Doug Richmond, Kerri Kuntz, Gus Gilman, Larry Heywood

This was a description by the poet of what occurred over two centuries earlier to Hannibal’s troops as he passed through the Alps. Interestingly, the pass that many feel is the route that Hannibal chose, Col de la Traversette, is the sight of possibly the earliest avalanche mitigation known. Monastery records describe a tunnel built in 1470, near the top of the pass designed to protect pilgrims from the upper slopes. For the next several centuries, avoidance and reinforced structures were the primary tactics to defend from avalanches

Jan 1, 2009

By T. Bernard, P. Dozolme

Electronic initiation devices appeared on the market more than 15 years ago and have definitely changed the rules of blasting. It becomes clear that this technology represents a powerful alternative to the traditional accessories. Electronic Delay Detonators (EDD) have attained solutions that were difficult and even impossible to achieve with the previous technology, thanks to the accuracy, usually inferior to one millisecond, and flexibility of the programmability range offering thousands of timing possibilities. Technological progress is long awaited to represent a step ahead compared with the last generation of products. In the case of electronic initiation, some limits nevertheless rapidly appeared, leading to the paradox of loosing operative and safety benefits, compared with the traditional technology it was supposed to outclass.

Jan 1, 2006

By M. Ramulu, A. Raina, A. Chakraborty, Jethwa Choudhury, Dudhankar

Application of digital image analysis technique for assessment of blast fragmentation is gaining grounds in India, very recently. Central Mining Research Institute, India made its maiden attempt to optimize blast design based on fragmentation assessment of one of the biggest opencast mines of Singareni Collieries Company Limited, India. Indigenously developed photoanalysis software called ‘FRAGALYST’ was used for measurement of blast fragmentation A series of trial blasts were carried out in overburden benches with ongoing blast parameters and pictures of muck pile were taken by video camera for image analysis. Cycle time study of loaders and dumpers was done to determine machinery performance for each and every blast. Optimization of pre-blast parameters like specific charge, specific drilling and post-blast results like shovel cycle time and dumper cycle time, was done to determine optimum range of fragmentation. Interpreting the mean fragment size (K50) obtained by image analysis the blast design parameters were modified.

Jan 1, 2001

By Johan Svard

"Two years of field testing have shown that blasting results are improved both in surface and underground applications when Nitro Nobel electronic detonators are used. The delay times canbe chosen with an accuracy of 1 millisecond over the entire time range (1 to 6250 ms). Since ordinary.high explosives have detonation velocities of up to 6000 metres/second, these high velocities make accurate and flexible delay times very interesting."

Jan 1, 1992

By Dale S. Preece

A Discrete element computer program named DMC @istinct Motion Code) has been developed for modeling rock blasting. This program employs explicit time integration and uses spherical or cylindrical elements which are represented as circles in 2-D. DMC calculations have been compared with measurements on bench blasts in the field with relatively good comparison. Structural rock mass characteristics have a significant impact on any blast and DMC has not, until now, included these effects. This paper discusses a recently added DMC capability for treating joints and bedding planes in bench blast simulations.

Jan 1, 1995

By James Rowland, Isaac Zlochower, Richard Mainiero, Michael Sapko

The National Institute for Occupational Safety and Health (NIOSH) carried out exploratory laboratoryscale studies to identify factors that may contribute to nitrogen oxides (NOx) production associated with non-ideal detonation of blasting agents. Explosive admixture with drill cuttings, loss of fuel oil in ammonium nitrate and fuel oil (ANFO) from wicking, ammonium nitrate dissolution with water, degree of explosive confinement, ANFO density, and critical diameter were identified as contributing factors to increased NOx production under the laboratory test conditions. Experiments were also conducted to examine the effectiveness of various additives in reducing the NOx production from ANFO, emulsion, and ANFO/emulsion blends. Aluminum powder, coal dust, urea, and excess fuel oil in ANFO formulations were tested and were found to reduce both the nitric oxide (NO) and nitrogen dioxide (NO2) production. Fumes measurements were obtained in the NIOSH underground closed chamber from the detonation of 4.5-kg (10 lbs) charges in schedule 80 seamless steel pipe and from detonations in light weight galvanized steel stove pipe. Some exploratory tests were also conducted with 0.8-kg (1.8 lbs) charges of pulverized ANFO initiated with 0.08-kg (0.18 lbs), 50/50 (Pentolite) boosters (in the NIOSH 12-ft (3.7-m) diameter steel sphere) to measure the degree of fumes production associated with post-detonation oxidation. Ammonium nitrate, emulsion and Pentolite boosters were also detonated in an oxygen-poor environment.

Jan 1, 2002

By V. Sastry

Signgareni Collieries Company Ltd. is operating the JK Opencast Project, at Yellandu, with a rated annual capacity of 1.6 Mt of coal with an average stripping ratio of 4.3. This opencast coal project has three working sections, OC-II block, C-Block and D-Block These workings are operating in close proximity to the JR-5 Longwall Shed, 26-Dip Incline, other structures of 26-Dip, and a Township. There were complaints about ground vibrations and fly rock problems caused due to blasting operations, especially in OC-II and D-Blocks. In view of this, studies were taken up to eliminate the problems of ground vibrations and fly rock.

Jan 1, 2001

By Steve Dillingham

The explosives business by nature is providing a specialized, valued service and associated products to a variety of customers whether mine, quarry or construction related. The level of performance demanded by the customer will typically coincide with his or her individual needs. Some will seek out the skills and knowledge of a blasting expert, while the focus of others is simply on production amounts.

Jan 1, 2003

By Barend Botha, Trevor Davids

The presence of an extensive soft siltstone layer in the middle of the inter-burden sequence of rocks at Syferfontein Colliery in the Republic of South Africa prompted tests to determine the effect of different mid-column decks of inert material in the siltstone layer. The objective was to achieve significant cost savings in explosives use whilst not degrading dragline productivity. An important factor that had to be considered was that the initiation systems available in South Africa are not accurate enough to ensure simultaneous initiation of explosives decks in a blasthole. A number of inert materials were tested including ash, drill cuttings, river sand and crushed stone. It was found that the ash, drill cuttings and river sand did not effectively attenuate the shock wave and that the risks of sympathetic detonation or partial disruption of one or the other explosives deck in a blasthole was high. This became much worse when the inert material was saturated with water. Crushed rock was the most effective in attenuating the shock wave, but this material was very expensive to use because it had to be imported onto the mine.

Jan 1, 2000

By Sarma S. Kanchibotla

In overburden cast blasting the explosive energy is used to move a significant percentage of overburden from the high wall to the spoil pile thus reducing the amount of material to be handled by machinery. However, the obvious trade-off between the extra explosive energy in the cast blast versus reduced dragline effort is complicated by an increased risk of damage to the underlying coal. This damage may not be obvious but inevitably leads to reduced coal recovery and may negate much of the benefit sought from cast blasting.

Jan 1, 1999

By Guillermo Silva, P. Katsabanis

The conventional approach to design wall control blasts relies on the borehole pressure as the most important explosive parameter. Borehole pressure is intimately linked to explosion pressure, which in turn is related to the detonation pressure of the explosive. For fully coupled charges, the borehole pressure is equated to the explosion pressure, while for decoupled and decked charges its value is typically calculated under the assumption that the explosion products behave like an ideal gas when they expand into the volume of the hole.

Jan 1, 2003

By D T. Froedge

At the 1990 Symposium of the Society of Explosives Engineering, D.T. Froedge, President of GeoSonics Inc., presented a paper entitled "Differential Topographic Vibration Isomapping", which detailed the capabilities of GeoSonics' new Iso-Seismic Service. In this paper Mr. Froedge described how one hundred or &ore free-standing miniature seismographs called Micro-Seis Units, randomly positioned around a blast, could accurately reveal the effects of sub-strata geology on surface ground vibrations. The paper went on to note the "regression analysis of scaled distance versus recorded particle velocity" as being an inadequate predictor of peak particle velocity. This is due to the fact that the calculated "regression analysis" formula for any site is predicted on the wars; case assumption because of a homogeneous and symmetrical sub-strata geology, a condition that rarely, if ever, exists.

Jan 1, 1992

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 Jerald E. Harris

"Often taken for granted, drill accuracy plays a major role in the relative success or failure of a blast.Expensive technological advances in equipment capabilities, drilling tools, communications, explosives, and timing can quickly be nullified by poor drilling."

Jan 1, 1999

By Gene Baker

A new Safety Library Publication (SLP), SLP-27, which is titled “Security in Manufacturing, Transportation, Storage and Use of Commercial Explosives” was recently released by the Institute of Makers of Explosives (IME). SLP-27 makes recommendations for both general security and enhanced security at explosives sites when security risk levels, declared by the Department of Homeland Security (DHS) using its Advisory System, have temporarily increased.

Jan 1, 2006

By Steve Dillingham

There are some blasters and blasting companies that just seem to have better safety reputations than others. This is in spite of the fact that they are essentially doing the same type of work under similar conditions. To achieve that enviable safety reputation, it simply comes down to a strong safety culture prompted by a responsibility for others, as well as yourself and your company.

Jan 1, 2003

By Mark A. Williams, James D. Humphrey

Without question, draglines are one if not the most effective tools available to the surface mining industry for overburden handling. With few moving parts and a two- or threeman crew, this machine silently sits and chews into millions of yards of overburden annually. A 100 cubic yard machine operating for 30 years will excavate three-quarters of a billion yards of material during that time. That is 750,000,OOO yards of material!

Jan 1, 1990

By Wang Xuguang, Tian Ruigi, Xiong Shangbin, Xiong Daiyu

Combining action features of explosive shock with those of natural lignocellulosic biomass structure, we have successfully developed a new explosive shock dilatation and separation technique for pretreatment of natural lignocellulosic materials in the laboratory. Based on a brief introduction to the technical background and experimental procedure of this new method, some preliminary experimental results are given and discussed: the scanning electron microscope (SEM) qualitative observation results show that for treated natural lignocellulosic sample such as corn cob etc., their length of fibre bundle shortens, fibre bundle arrange disorders, biomass appearance and structure of samples largely change to be dilatation and loose state. The dilute acid hydrolysis quantitative measure results show that for treated samples, the overall yield of the reducing sugar largely increases, hydrolysis rate of corn cob sample is over 80%, rate and speed of hydrolysis are increased by times.

Jan 1, 1998

By John W. Gunnett

The purpose of this afternoon’s presentation is to highlight the investigative proce dures employed to complete an engineering audit of a mining operation. Skelly and Loy has been retained to perform operational audits throughout the nation’s coal fields, The need for such studies is generally associated with long term coal supply contracts and is typically initiated by the utility company. However, a number of projects have been commissioned by mining companies while others have been jointly funded by the utility and mining company.

Jan 1, 1992