Search Documents

By Ray Jambakhsh, Gabrielle Bourget

In the summer of 1998, Ontario Hydro awarded a contract to demolish an obsolete and inefficient chimney by blasting. The Ontario Hydro Thunder Bay Thermal Generating Station (T.G.S.), is a fully operational hydro thermal generating station located in Thunder Bay, Ontario, Canada. The Chimney was a 356 ft (108 m) high freestanding structure constructed of reinforced concrete with a brick liner. Falling the chimney required careful planning due to the highly sensitive structures and equipment which surrounded it. Damage either sustained to the existing systems through ground vibrations or direct contact would have resulted in expensive power outage and/or lost production. The role of Explotech Engineering Ltd. on this project was to provide and evaluation of the proposed demolition procedure, defme the predicted and maximum seismic vibrations at sensitive structures including underground services, conduct pre-blast / post-blast inspections and recommend various safety precautions. The general contractor for the project, LeBrun Northern Contracting Ltd., of Thunder Bay, Ontario was responsible for all site preparations and post-blast clean up. All demolition blasting calculations and operations were conducted by Dykon demolition experts from Tulsa, Oklahoma. On September 13, 1999, the chimney was successfully demolished. Extensive analysis of the vibration records and visual post-blast inspections of the surrounding structures concluded that the demolition event induced no damage to any of the Ontario Hydro facilities.

Jan 1, 2000

By Paulo José Costa Couceiro Junior, Manuel Lopez Cano

In 2011, two historic outcrop rocks known as Teffé and Itapema located in the navigation channel of the Port of Santos, Brazil (Latin America’s largest port) – were excavated by drilling and blasting techniques. Sensitive structures - a passenger terminal and an 80-year old warehouse were exposed to ground vibrations generated by underwater blasting. The warehouse had existing structural problems due to a combination of factors such as the presence of an unstable soil, previous repair work, and intense seismic events generated by the daily traffic of cargo trains nearby during eight decades. Since the worsening state of the structure was attributed to ground vibration from underwater blasting, particle velocity time histories generated by underwater blasting and by passing trains were monitored. By analyzing the energy spectral density of these events using spectrograms, it was possible to observe the seismic energy levels in time and spectral domains. Since the hysteretic energy dissipation by structures is related to the duration of the seismic event and the limited dissipation capacity of the structure, one could expect damages to appear in the structure once energy levels exceeded this dissipation capacity. As the quantity of energy transmitted to the structure is proportional to the duration of the seismic event, the transmission of seismic energy to the warehouse structure over time was more significant in the case of the train-induced ground vibrations (several minutes) than those generated by the underwater blasting (few seconds). Thus, for the warehouse, train-induced ground vibrations have a larger impact on the structure rather than ground vibration generated by controlled underwater blasting techniques.

Jan 1, 2016

By Peter Stamos

In the summer of 1989, Material Service Corporation (MSC) was expanding its Thornton limestone mining operation putting them in close proximity to two shopping centers in Homewood. In other communities, similar expansions had been met with community protests and lawsuits seeking injunctions to stop operations.

Jan 1, 1991

By Darcey Baker

Quarry Blasting is usually boring, and that is how we like it. By this, boring means routine, straightforward, meat and potatoes blasting. Quarries typically will not utilize cast blasting, coyote tunnels, or any of the other more spectacular blasting techniques – just plain, old day-in and day-out quarry production and possibly overburden blasting. Differences in material characteristics, mining method, equipment availability, and target markets all play a part in determining the blasting procedures employed at any given location. However, variables exist everywhere and with foresight and planning, effects of tangible variables can be minimized. Variables caused by geology, weather, neighbors, or limitations caused by major plant or mobile equipment are, generally speaking, intangible; and leave the operator with finite options to improve or modify blasting procedures.

Jan 1, 2009

By B S. Petri, N T. Rouse

Underground limestone mines generally lack air pressure monitoring procedures and instrumentation guidelines. The blasting industry also lacks an applicable source for air overpressure levels that are produced by blasting operations in underground mines. This became apparent during the development of a new underground limestone mine, where overpressure levels from production blasting needed to be estimated. During the development phase of the mine, it was imperative that newly constructed underground structures be capable of withstanding the overpressure produced by blasting. Therefore, a study was conducted to (1) identify and review any published studies for data that may be applicable, (2) identify the appropriate equipment required to record the overpressure levels, (3) determine the proper procedures for setting up the equipment and recording overpressure, and (4) provide an understanding of the nature of the air overpressure in a developing mine.

Jan 1, 2014

By Julijan Bratun, Joze Kortnik

Production of technical stone is an important economic branch in Slovenia. In 2009, we had 95 dolomite quarries, 27 limestone and 6 silicates quarries, according to the Ministry of Economic Affairs. Together they produced nearly 15 million tons of aggregates. The production in quarries is mostly performed with drilling and blasting method and only a minor part with other method like mechanical mining method.

Jan 1, 2011

By Robert Hopler

After the disbanding of the Gunpowder Trust Association in 1904, the Association of Independent Powder and Dynamite Manufacturers was formed, followed in May of 1906 by the formation of the Association of Manufacturers of Powder and High Explosives. Due to a lack of success in attracting all manufacturers to membership, these organizations did not survive.

Jan 1, 2014

By Manish Uttarwar, Rajendra Yerpude

India is the third largest producer of coal and the fourth largest in terms of coal reserves in the world. However, new research quite ironically projects that despite the continuing growth in domestic coal production, the country’s exploding economic growth will position it to be the biggest coal importer by 2020. India’s inability to meet the domestic coal demand is mainly attributed to low rate of production, increasing stripping ratio, non use of appropriate technology etc. of coal mining operations here. Presently Indian surface mines which have to shoulder the onerous responsibility of augmenting the coal extraction rate at an even brisker pace are mulling bigger, better and more efficient operations ensuring commensurate rise in stripping work as well. This mammoth task can be accomplished only by deploying smart technologies. In this perspective, cast blasting of overburden emerges on the horizon as a promising alternative for enhancement of the production and productivity of Indian open-pit coal mines.

Jan 1, 2009

By X. Gumede

A model is being developed to quantify the benefits for mining houses resulting from the reduction in greenhouse gas and energy consumption by the application of innovative blast designs in addition to direct financial benefits throughout the mine to mill value chain. The conversion from shock tube initiation systems to electronics and some changes to powder factor measured on an open pit mine had previously been used to show significant improvement on blast outputs. Benefits were realised on drilling, blasting, loading, hauling and beneficiation. Quantification of the relationship between powder factor and reduced greenhouse gasses is investigated in this study. The study has highlighted new data that must be recorded and hence some assumptions were made as to fuel consumption and the energy in crushing was obtained from the Bond work equation. The mine to mill projects in an open pit platinum mine and a quarry produced energy savings and reduced greenhouse gas emissions associated with the careful application of explosives and blast innovations. The less fines project showed an increased carbon footprint. The model provides a new insight into how project feasibility should be decided based on economic and environmental viability.

Jan 1, 2012

By Thomas L. Barkley

"In early 2015 the Seed Waveform method was used to measure the Geologic response of the MesabiIron Formation to explosives energy input. This single charge wave form was then used to design acritical first blast at a newly developed Taconite mine. This initial blast had several irregular restrictions on design and performance. It had a very unusual “Frying Pan” shape, the regulatory agency required that no fly rock land in State owned waters less than 200 feet (61 m) away, there was no open face to blast to. Design criteria included the need to detonate the blast with two sinking cuts, and have the sinking cuts meet through a narrow neck between the cuts. All these had to be met using a 16 inch (406mm) diameter hole."

Jan 1, 2016

By Marlyn King, Kevin Peterson

Power Decks are voids created in the bottom of the borehole through the use of a suspended Super Plug. Explosive energy is started downward at initiation creating high pressures which find relief at the comers of the borehole cylinder in the bottom of the hole. This relief creates a horizontal break to the neighboring boreholes - the same effect as presplitting. This “presplit” represents a change of mass to.the explosive energy,and it is reflected upward in the more efficient form of tensile waves. This provides better use of the explosive energy than compression waves. This technique has created a new way of looking at the ways that explosive energy is transported through the rock mass.

Jan 1, 2002

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 A B. Opperman

For many years explosives energy has been utilized in mining and construction as well as many other applications which are vital to our way of life. Many types of explosives have made their contribution as technology has moved forward. One of the best known was dynamite, which for many years was the mainstay of explosives users. Although dynamite had many advantages over its predecessors, it had the principal shortcomings of being somewhat hazardous to handle and was known as a headache producer.

Jan 1, 1975

By Chulgi Suk, Hoon Park, Hyonsoo Kim, Hakman Kim, Sangho Cho

Dust emission from blast demolition and other construction activities can be a nuisance; it is widely recognized that fine particles less than 10 µm in equivalent diameter (called PM10) may cause health problems. Mist spray systems, such as rain guns, sprinklers, water/surfactant sprays (or foams) etc., are some of the most effective dust suppression methods. A large amount of research has showed that when water droplets are produced in an equal amount to that of dust particles, the airborne dust is suppressed by the agglomeration of dust and mist particles. A method for generating micro-sized mist from water, achieved by the detonation of explosives in the water tube, was suggested and is called the ‘detonationdriven water bag burst system’. There are many experimentally observed limitations of the explosioninduced water break-up process. The water bag explosion tests were simulated using the AUTODYN software, in order to investigate the aerosolization mechanisms of the detonation-driven water and water break-up process into micron-sized droplets. As a result of the numerical analyses, the diffusion direction of water when detonating in the central interior part of water tube was radioactive and significantly stronger than when detonating in the bottom exterior part; this is due to the compressive flow of the volume change inside of the water tube, which resulted from the blasting wave inside of the tube, as well as the reflected pressure on the ground. Blast tests of full-scaled reinforced concrete columns were conducted to verify the effectiveness of the suggested detonation-driven water bag burst system. The water breakdown and dispersion that occurred while blasting the reinforced concrete columns were observed using a high-speed camera, and dust generation was monitored using four density detectors. The suggested detonation-driven water bag burst system showed that the average dust density decreased by up to 7 mg/m3.

Jan 1, 2016

By Jean M. Bouvet, Pierre M. Vuillaume

There is not just one ANFO: ANFO explosive behaviour depends significantly on the blasting conditions and on its physico-chemical characteristics. For instance, ANFO effficiency increases whereas AN porosity is higher and consequently loading density of the explosive is less. This can be argued against generally admitted ideas. Therefore, the efficiency of industrial explosives related to ANFO (for example "relative weight strength" or "relative bulk strength") is a tool that must be used with caution.

Jan 1, 1993

By Nikolaos Petropoulos, Daniel Johansson, Håkan Schunnesson

The optimization of the explosive performance is of great importance since blasting is extensively used in civil projects and mining industry. An improved understanding of how the energy from the detonation of an explosive is transmitted to the surrounding rock mass is critical information for the proper selection of an explosive. Therefore, an extensive study was done on the influence of the blasthole diameter on the Velocity of Detonation (VoD) and the detonation front curvature. In this study, pure emulsion was tested in confined conditions to better simulate the behavior of the detonation of the explosive in rock mass conditions. A methodology is proposed for carrying out the evaluation of the explosive performance. The blasthole diameter of the samples varied from Ø 25 mm (0.98 in) up to Ø 65 mm (2.55 in). The confiner was a magnetic mortar cylindrical sample with mechanical properties similar to a rock mass. A streak camera and VoD probes were used to measure detonation front curvature and VoD. The data was analyzed and correlated with the physical parameters of the explosive. Additional to this, the data was further used to calibrate numerical models in LS-Dyna.

By Jeff Dean

As the Society celebrates its 35th year as an explosives industry association, it is clear that we are part of an industry that covers many sectors of economic activity. We are the voice of those who use, transport, store, manufacture, and dispose of commercial explosives products and others that serve the end user of explosives products. Along with other associations in this industry, we have a combined membership of hundreds of companies and tens of thousands of individuals in the U.S. and around the globe.

Jan 1, 2010

By Eric Roller, Elliott Giles

All flyrock incidents have the potential to result in injuries or fatalities that can result in loss of company reputation, license to operate with clients, and bear the exposure to high cost liability. From 2007 to 2009,one NA Quarry and Construction Business experienced a series of flyrock incidents. In the spring of 2009, this business declared that the frequency and severity of Flyrock Incidents had reached an unacceptable level. A Flyrock Elimination Program was launched.

Jan 1, 2012

By Winfried Rosenstock, Carlos Orlandi

Along the Pacific West coast of Latin America there are several large operations of metal mining activities. To mention only a few: Chuquicamata in Northern Chile moving daily approximately one million t of copper ore and waste, Cerro Verde near Arequipa in Peru, or lanaccocia. Apart from the coal deposits in north-east Columbia it is mainly to deal with metal-mining, which has due to geographical reasons relatively high cash-cost. This sector of mining is traditionally severely depending on the world-market.There are reasons to believe that the world-market will remain on a low price level and some analysts predict that in general the price-level will continue on low basis for the next decade. The cash-cost factor becomes therefore even more important as it already is. The goldprice development during the year 1999 illuminates that market changes can quickly lead to a severe crisis which forces the shutdown of mines with cash-costs close to or above the present market price per ounce. The breakdown of the cash-cost shows, however, that there are ways to overcome even the crisis like it struck the low-grade open pit goldmines around the world. Especially hitherto the “Electronic Option” is the only solution as the possible reduction using advanced technology based on the application of electronic detonating systems and newly developed special ignition procedures. The electronic option will lead to tremendous cost reductions similar to the results of research operations Thiess Contractors, Brisbane, Australia have carried out in Australia in 1998 and 1999. The electronic option allows a comprehensive integration of side effects of the blasting process which in the past could not have been achieved so far. Electronic initiation can achieve secondary effects which have an additional and positive impact on the level of costs. Appropriate application can enhance the production of material which will reduce the primary crusher costs or even make a primary crusher operation obsolete.

Jan 1, 2000

By David Flores, Benjamin Cebrian

Gold mining require high levels of dilution control due the high value of ore. These types of operations employ short benches, which are suitable for ore control, lower displacement and more representative block models. However, shorter benches makes fragmentation by blasting difficult because blast designs tend to be stiff in regards to burden/bench height ratio. This is especially relevant in hard, massive ore bodies where usual drilling diameters lead to poor energy distribution. In regards to control ore loss and dilution, there are different techniques to minimize both, which include: panel blasting, buffer blasting to muck piles and differential loading of areas of the blast bench. All of them should be sequenced with appropriate displacement along the ore/waste contacts. This paper describes extensive engineering approaches to achieve both dilution control while not hurting fragmentation in the very hard, massive ore sections of a mine case study. Ore Tracker microchips are used to correlate performance of these designs at the SAG mill (bottleneck of this specific operation). Another gold mine uses the same technology to detect when and where operational dilution is happening. The system tells where flagging of the different ore bodies has been followed in order to detect which operators pass the excavation limits beyond ore control flagging.