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By Sandor Nagy

The Explosive and Blasting Department of the Hungarian Mining Research Institute is responsible for the research and development of industrial applications of explosives. Appropriate explosives technology is developed for each application, including the explosive demolition of structures, which belongs within our charge.

Jan 1, 1977

By Anders Nordqvist

LKAB operates an underground iron ore mine in Malmberget in the northern part of Sweden. Twelve different orebodies are mined today using both longitudinal and transversal sublevel caving as mining method. The town of Malmberget is located close to the mining area. The need for urban transformation, moving people and houses, is evident for many reasons. The mining methods used have inherent subsidence issues and there are also vibrations from blasting and mine induced seismic events.

Jan 1, 2018

By David Nemir, Jan Beck

A challenge in materials science is the production of a bulk solid material from a powder precursor. One solution is to use shockwave consolidation whereby a ductile tube is loaded with the powder of interest and then surrounded by an explosive. A detonator at the top of the explosive column initiates a symmetrical high-pressure pulse that moves inward and down the tube, causing the tube to deform and the interior powders to consolidate into a dense, well bonded bulk material.

Jan 1, 2016

By R. Franfield, W. J. Birch, L. Bermingham

Previous researchers have put forward two different theories as to the origin of air overpressure from quarry blasting. In 1980, Siskind et al postulated that the initial face movement gave rise to the displacement of air and that this resulted in the air overpressure pulse. However in 1990 McKenzie et al carried out research that indicated that the air overpressure pulse came into being as consequence of the shock wave created by the detention of the explosive charge in a blast hole, rapidly propagating through the rock and then impacting on the quarry face.

Jan 1, 2013

By David Kennedy, Noel Hsu, Miguel Araos

The use of bulk explosive for mining applications started in the 50’s. Since then millions of tons of that material have been transported by road. However during that time, there have been several road incidents involving them. This type of incident has forced the explosives manufacturers as well as regulatory organizations to look for a better classification of explosives in order to regulate the industry as well as to mitigate community concerns over the classification of mixtures of substances that are regarded as precursors to explosives.

Jan 1, 2006

By Michael Wieland

Sharp transient stress waves generated during the delay blasting of underground coal can damage unfired borehole charges remaining in the delay pattern. These tremendous stress pulses in coal bear a strong resemblance to underwater shock waves, despite differences in rise times, damping rates, and scaling relations. "Shock wave" terminology is adopted to distinguish the sharp transient waveforms propagating through the coal from the gas-driven stresses that rift the coal. Reported waveform characteristics of shock waves through underground coal were utilized to design a simulator test for rating the impact resistance of cap-sensitive explosives. Theoretical minimum borehole separations were determined for each cap-sensitive explosive from the requirement that worst-case waves hitting an unfired charge would not exceed its impact resistance rating. Rugged explosives have higher impact resistance and will function properly at smaller borehole separations. Additional work is required to verify the findings from the simulator technique and modeling relations reported here.

Jan 1, 1990

By Thomas Palangio, Lyall Workman, Jack Eloranta, Tom C. Palangio

The fragmentation distribution of the blasted ore is an important descriptor of blasting results. Traditionally it has been hard to measure quantitatively. Developments in image analysis over several years makes it more feasible to measure fragmentation before crushing on a continuous basis. Post crushing, mill feed distributions can also be measured.

Jan 1, 2007

By W. Boas, R. Silva, D. Yumi, L. Steffen

The continuity of the flow and stages within the mining process is essential to achieve success in its operation and results, especially when it comes to a gold mine. During the first seven months of 2022, crushing at the Morro do Ouro Mine had 19 stops in the primary crusher due to equipment blockage/obstruction, this could be due to the size of the material that was blasted with explosives and fed. The feeding of coarse material to the crushing plant impacts the operation in several ways, for example, premature wear of the equipment, reduction in the supply of the remainder of the beneficiation, reduction of the buffer pile and damage to the conveyed belt. In a mine located far from the community, the fragmentation improvement is mainly related to load increments or some other relatively simple change. However, when it comes to a mine located close to communities, alterations of this type must be analyzed in detail, as it can have an impact mainly in relation to vibration and flyrock. Aiming to improve the efficiency of the blasting, mainly in relation to the result of fragmentation, a project was created to improve the efficiency of the blasting with a focus on reducing the crushing stoppage and reducing the amount of material discarded due to inadequate granulometry. During the evolution of the project, several improvement solutions were proposed, for example adjustment of the power factor in relation to the geological characteristics of the rock mass, drainage, blasting geometry, vibration reduction techniques and several operational improvements. By using the techniques and methods identified as improvements during the project, it was possible to observe and quantify improvements in relation to the fragmentation of the blast. During the months of January to July 2022 there were 19 events. It was estimated that at this rate there would be 14 more blockage events, but there were only 3 events and that meant a 79% reduction in blockage. In addition to the reduction in crushing shutdown events, there was also a 53% reduction in the amount of ore that is discarded due to inadequate granulometry and, with that, the feed rate of the grinding system was able to reach the maximum feed limit due to the material being fed to the mill well fragmented, contributing to increase the production and productivity of the beneficiation process at the Morro do Ouro Mine in Paracatu-Minas Gerais-Brazil.

Jan 1, 2024

By Greg Quinn

After a long week of work in Colorado Springs this past July, I was looking forward to flying home to start a long anticipated family vacation. As I grabbed my seat on the plane, a man sitting next to me innocently inquired, to the row as a whole and not to me in particular, “I wonder what the weather will be like in Phoenix”? To most people, this is a common (maybe the most common) topic of casual conversation. To a meteorologist that just dealt with six thunderstorm delays at a major golf event over 4 days, well, lets just say the smirk on my face said it all. After giving my flight mate a detailed forecast and a short explanation on why I would know such information, I sensed, correctly, the inevitable follow up question was coming. “Why would you need a meteorologist at a golf tournament?”

Jan 1, 2012

By Alan B. Richards, Aleks Todoroski

The undesirable effects of blasting fumes can be controlled by minimising the amount of fume created, and by avoiding the movement of the fume plume to sensitive locations. Substantial progress has been made by the blasting industry to reduce the amount of fume typically created by blasting, but at this time no specific blast can be guaranteed to be ‘fume free’.

Jan 1, 2017

By Ian Tolliday

Emulsion Explosives manufacturers are aware of the destabilizing effect that the presence of inorganic impurities such as magnesium and iron and organic impurities such as naphthalene sulfonates and alkyl amines can have on their emulsions. This destabilization often manifests itself as severe crystallization and subsequent product loss. This paper describes the performance testing of specifically developed emulsifiers which give greatly improved emulsion stability in the presence of high levels of impurities. The test work involved a series of stability tests using ammonium nitrate doped with various levels of crystal modifier and anti-caking agent. A further series of tests were done to evaluate the stability using ammonium nitrate doped with various levels of iron and magnesium ions.

Jan 1, 2018

By Mark S. Stagg, Stephen A. Rholl

The firing times of millisecond-delayed initiators are random variables that exhibit varying degrees of scatter. This scatter can cause crowding and overlap of adjacent delay periods, which results in adverse effects on safety, fragmentation, and blasting vibrations.

Jan 1, 1988

By Dale Preece, Vanessa Berg

This paper presents a two-pronged vulnerability analysis approach for treating minimally reinforced concrete (RC) structures subjected to explosive events. This work was motivated by a heightened interest in homeland protection involving both malevolent and accidental explosions and the need for assessment of critical facilities subjected to an explosive detonation. The first part of the analysis approach employs the commercial 3-D Eulerian-Lagrangian hydro-code AUTODYN, while the second part of the analysis employs Single-Degree-of-Freedom (SDOF) methods, each predicting the dynamic response of the minimally RC walls, slabs and columns to explosive loading. The concrete is treated with the newly developed RHT (Riedel, Hiermaier, Thoma) constitutive model, which accounts for failure mechanisms in brittle materials. Predictions from AUTODYN are verified using the equivalent SDOF reinforced concrete code, SPAn32, developed by the US Army Corp of Engineers and agreement between the results indicates a high level of accuracy in both methods of analysis, allowing for accurate predications of airblast-structure interactions and failure mechanisms.

Jan 1, 2004

By J R. Hearst, T R. Butkovich

Explosive-induced fracturing and permeability enhancement far from a free face were studied. A one-dimensional computer program, SOC, was used to predict the total failure-associated distortional strain, ef. Laboratory and field experiments associated the calculated ef with the observed fracture and permeability enhancement. An ef value of 0.015 corresponded to the observed radius of effect, which was about seven times the cavity radius and was consistent with predictions from SOC and from the literature.

Jan 1, 1976

By V R. Sastry, D P. Singh, N R. Thote

Rock parameters which are uncontrollable impose restrictions on the procurement of desirable fragmentation. Blast design parameters which are controllable prove to be important tool in blasting operations. An attempt was made by the authors to investigate parameters which causes big oversize boulders in overburden blasting. A case study of coal mine is discussed in this paper.

Jan 1, 1995

By Douglas Rudenko

When blasting complaints come, as an industry we often immediately look to the ground vibration as the source of the trouble. Often times we overlook or place less emphasis on the collected air overpressure data. Air blast like ground vibration is an undesirable side effect of blasting and can produce considerable structural response.

Jan 1, 2002

By R. Wharton, M. Bagley

The paper reviews the likely introduction of a European directive covering the sale of pyrotechnic articles in member states of the European Union. The background and structure of the directive are described, together with the range of products covered (which includes fireworks, theatrical pyrotechnics, vehicle airbags and seat belt pretensioners, and certain cartridges). Possible timescales and the implications for industry are also discussed.

Jan 1, 2007

By Chen Aiping, Wei Banyun, Chen Canchang

"The gaseous explosives consisting of combustible gas and combustion-supporting gas wereused in the opening end of a steel pipe and the ignition was in the closed end of the pipeusing continuous air feed within the permissible length limit of industrial equipment, theexperimental results show the mechanisms of forced transition from combustion todetonation and what is the effective equipment for the transition."

Jan 1, 1993

By J. Meissner

In this paper vibratory crack response is compared to that produced by volumetric changes in foundation soils induced by natural events. These natural phenomena include changes in the water table, changes in soil moisture, and formation of ice lenses to name a few. Previous papers have compared vibratory responses of cracks to atmospheric effects such as those produced by the passage of weather fronts and daily changes in temperature and humidity. Periodicity of these atmospheric effects is on the order of a day to half a dozen days. Thus it is possible to observe atmospheric effects with measurement over a period of weeks to several months. On the other hand, crack response produced by volumetric changes in foundation soils occurs over a period of many months and/or may be seasonal in nature if not longer in the case of drought. Thus its measurement requires long periods of observation (many months to significant fractions of a year) or observation during critical seasons. Since it occurs over long periods of time, its observation may be obscured by climatologically induced crack response. These soil volume changes are compared with climatic data to describe the correlative nature of crack response in time with the soil volume change phenomena and likely climatic causes.

Jan 1, 2009

Previous approaches to pre-split blasting theory have tended to concentrate on the mathematics of dynamic stress wave interaction, whilst only recognizing some interaction with quasi-static stresses induced by expanding gases in the boreholes. However the decoupling used in pre-splitting is specifically designed to reduce dynamic effects to a level that a small degree of radial fracturing is created around the borehole which is emphasized and extended by quasi-static gas effects. It can thus be argued that the process has more in common with hydrofracture than with more conventional use of explosives.

Jan 1, 1984