Search Documents

By Daodu Opeyemi

This paper describes several damages of blasting operations on some case studies, analyzes causative factors, and emphasizes preventive measures. Due to several complaints from some host mining communities as a result of blasting operations; two quarries from Nigeria suburbs were visited for study. The blasting design parameters in the mining companies were examined. Also, the history and existing conclusion of the neighboring buildings were studied using structured questionnaire, personal contact and visual examination. From the study carried out, it was discovered that varying negative environmental and socio economic problems resulted from the effects of vibration and flyrock on the nearby agro mining communities. The consequences are not limited to distortion of landscape but also include extinction of some animals, poor agricultural productivity; such as damages to economic trees and reduction in the yield of crops, health problems as a result of shock resulting to psychological disturbances, communal conflicts, blast induced cracks of structures and sometimes total collapse of host agro mining buildings, thus indicating that most mines did not comply with the safety concept of the existing environmental laws and regulations. Based on the results of the study it was recommended that proper blast design of quarries/mines should be conducted and the compulsory use of seismograph will be crucial in developing predictions. Environmental impact assessment should always be conducted before, during and after each blasting operation. Other possible control of vibration, flyrock and airblast, are also discussed in the paper

Jan 1, 2009

By Francisco Sena Leite, Vinicius Miranda

Mine blasting is directly associated with ground vibration. If these affect critical structures (buildings pit walls, etc.) they must be mitigated to reduce the environment and social impacts. Vibration monitoring and control is one of the most important procedures in blasting because it will impact short and long term incidents associated with this blast effect. Technology moves ever forward, and today we have personal devices that are equipped with an array of sensors, for that reason the authors decided to investigate the possibility of using a personal device to do vibration control. This case study compares the same blast measured with a traditional seismograph and a smartphone. To validate this new methodology, attenuation laws were built with data from a traditional seismograph and a smartphone application. Predictions were also made prior to a set of blasts. Residual analysis was used for data validation from the two different sources. From the performed analysis, to prove the validity of this new methodology, the normality tests for statistics residues analysis proves that it is possible to infer that the model has a null residual mean and a small residual error. The achieved results show the accuracy of these devices, the authors pretend to show the potential of this equipment and open a completely new door for vibration analysis.

Jan 1, 2018

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 Michael Karmis, Syed Muhammad Tariq, Zeshan Hyder

Secondary or boulders blasting is a regular feature of quarrying operations in Pakistan, especially in cement and stone crushing industries. The main reason for secondary blasting is the production of a large number of boulders during the production blast. These boulders are larger than the feed hopper of crushers and require further breaking. The complex geometry of boulders, relative lack of restraining burdens, and the availability of number of free faces make this kind of blasting more hazardous than production blasting. Secondary blasts have generally unpredictable results and may cause flyrock, airblast, and over-crushing of rock material. Thus, it is essential to have an appropriate amount of explosive charge/powder factor, and for it to be properly distributed in the blast hole. The greater the amount of explosive over the required amount, the more violent is the blast, which will result in more flyrock, airblast, and excessive crushing of boulders.

Jan 1, 2012

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 Neal Lee, Braden Lusk, John Silva Castro

One of the most common assumptions regarding the use of ANFO versus utilizing 100% sensitized emulsion is that ANFO “turns over” the muck-pile better, due to the “higher gas volume” supposedly inherent in ANFO. This paper examines this assumption and provides quantitative data for analysis. Total gas volume from each product was evaluated using Orica’s I.D.E.X. Code analysis. This analysis was used to determine if gas volume is a significant contributor to differences in fragmentation and movement between blasts utilizing the two different products. A constant drilling and blasting cost per yard for given cut depth, hole diameter, stemming height and rock type was utilized. The cost per yard was held constant by adjusting patterns considering product, accessory, and drilling costs. Photographic fragmentation analysis, dig rates measured quantitatively through production tracking and time studies and qualitative information about the diggability of the blast provided through video recordings were used to evaluate performance. The data collected during the study is presented and recommendations are made regarding the performance of ANFO and Emulsion holding other variables constant for a limited number of blasts.

Jan 1, 2012

By Robert Cefalo

Drill and Blast Engineer Abstract In 2019, the Bingham Canyon Mine, owned by Rio Tinto Kennecott Utah Copper Company, mined through the active underground that dewaters the pit. The active underground required the limitation of vibrations to avoid catastrophic damage or damage that would require work to the shotcrete and additional roof support. The surface design of the current sector next to and through portions of the active underground. The drill and blast group was required to test site law vibration parameters to ensure that vibration limitations were lower than limits set by the underground management team. Seismographs were used to validate the vibration prediction model and check performance of blast in areas of the underground. The bench conditions and limited pounds-per-delay created large obstacles for the blasting team, making it difficult for them to accurately load the pattern with the number of decks in the blast. Methods were used to improve the loading instructions and ensure that each hole achieved pound requirements based off of the distance to the underground that it was designed to protect. The project evolved from start to finish, and the process to estimate distances and loading improved to make the blast a more repeatable process for the size of the project.

By Ed O'Connor, Per-Anders Persson, Manhong Zhou

This chapter deals with the concepts of shock waves and detonation waves together, because a detonation wave is really a shock wave, supported by the explosive reaction that the shock wave ignites and propagates as it travels through the explosive material. In the context of rock blasting, furthermore, there is justification for treating shock waves and detonation waves together, because the mechanical effect of the detonation in an explosive in a drillhole in rock is propagated and its effects are spread throughout the surrounding rock by means of a shock wave. The overall performance of an explosive in rock blasting or any other application is of course dependent on how much thermal energy is released in the chemical reaction that occurs when the material detonates, and on how much useful mechanical work the reaction products can do as they expand. A major portion of this chapter deals with the prediction and measurement of explosive performance, a subject which is now still in a process of rapid development.

Jan 1, 1997

By Nolan Eckroade

The demand for blast optimization within the quarrying industry calls for more effective, faster and safer methods of quantification of blast performance. Drones provide the ability to safely and quickly capture high resolution imagery of a muckpile for use in fragmentation photo analysis. Oversize material within a muckpile is an expensive and universal problem affecting quarries, especially in situations where cap rock is present. Although the amount of oversize material in a blast is a key indicator of blast performance, it is difficult, hazardous and slow to measure across an entire muckpile using traditional methods. By piloting a drone using an automated flight plan with set amount of overlap across images, the images can be processed into a single, high resolution orthomosaic image for use in fragmentation photo analysis software.

Jan 1, 2018

By Michael Wieland

Smoke/fume measurements from rapid transitory charge reactions are not wholly comparable with thermodynamic reaction code (TDRC) results, since quenched chemical reactions yield nonequilibrium concentrations. Though the work output and major reaction products are usually rendered with minor deviations, the toxic fumes and other minor concentrations reveal some major discrepancies. Work output for charge formulations in underwater or fixture tests were theoretically resolved with work-principal models that form a rough thermodynamic trajectory. Stalled nonequilibrium concentrations are rationalized by finding the underlying quenched reaction(s). The wide relevance of the Zeldovich radical-chain mechanism that transforms nitrogen oxide was previously recognized. The work-principal model (WPM) represents reaction quenching with off-trajectory constraints to render the fumes, without noticeably readjusting the work process. When restraints that characterize the confinement are WPM tractable, the resolution of critical reaction mechanisms is worthwhile, since they remain useful, regardless of the rich, neutral or lean stoichiometry of the charge formulation.

Jan 1, 2012

By Robert B. Hopler

The history of bulk loaded explosives begins with the loading of black powder and RRP (Railroad Powder) into vertical boreholes. The early air place, net of black powder and nitrostarch dynamites is covered, as are the brands and formulas of the nitroglycerinsensitized "Bagged" powders.

Jan 1, 1993

By Lon Santis, David Buckwalter, Ken Steinmetz

This paper describes a magazine security system using two readily available cellular telephone-based technologies. The system is comprised of vibration sensors and remote cameras. The system is used at a Bureau of Alcohol, Tobacco, Firearms, and Explosives (ATF) licensed explosives storage location in Pennsylvania to comply with PA Department of Environmental Protection (PADEP) regulations. The system provides instant notification to the licensee via cellular modems, text messaging, phone call, and e-mail. Likewise, the licensee can control the system remotely over the internet and using text messaging commands. The vibration sensors attach to the door of the metal type I magazines magnetically and detect any movement or vibration. The cameras trigger on movement and thermal radiation changes and can also be triggered manually to check alarms received from the vibration sensors. The previous system was comprised of a base unit and magnetic strips. The magnetic strips were powered by a hard line from the control unit and mounted on the doors and top of magazine creating a bond, that when broken triggered an alarm. Our main issues with the unit were the delay in alert times and tech support. Because of these issues, we decided an upgrade was necessary. Compared to that previous system used at this site, these new systems are highly affordable, carefree and reliable.

Jan 1, 2014

By Michael Wieland

The thermodynamics work-principle was used to develop the rupture-fracture-throw (RFT) model for ranking the performance of reduced-density explosives when shot in rock or other stratum. The RFT model revises techniques used for the rock-water-jelly (RWJ) model, where the reaction-zone remains trapped within the rock/stratum. Therein, ranking of performance refers to trends for the two resolved components of the total expansion work: the reversible mechanical work taken as the heave and the residual irreversible portion, taken as the undissipated shock. For numeric tractability, the RFT and RWJ thermodynamic efficiency were taken equal, while the RWJ late-stage confinement was replaced with restrained venting through the rock, to render the RFT inefficient heave. The transfer of heat from the reaction-zone was neglected and the root-power formula was used to render the gas-covolume. Ranking trends were found for a generic charge formulation over a wide ranging density, with underwater results noted for comparison. Realistic compositions, some with natural resource materials, were treated for just typical and reduced density. Rock characteristics, ranging from hard rock to weak stratum, were represented by their density and rupture compression strength. Quantitative test results for shock or heave in rock remain difficult, so qualitative guidelines remain helpful when reviewing the graphic trends. Theoretical refinements for rock fragment size-distribution remain under development, though some relationships are touched upon to gain insight.

Jan 1, 2011

By Lawrence Mirabelli, William Hissem, Gary Veltrop

Capital Quarries Company, Inc., Jefferson City MO produces aggregate products for road base, asphalt, concrete and concrete block. With their production quantities small in comparison to those produced by the goliaths of the aggregate industry, they find it necessary to constantly stay on the leading edge of best practices for cost control, process and production improvement to sustain a successful business. In the words of Eric Strope, President, “The safety of our employees is foremost. They all work hard each day. They are focused on keeping our cost to manufacture down. As I see it, we cannot work any harder so we must work smarter!”

Jan 1, 2009

By Peter Cameron, Tom BoBo

Comminution, being the energy intensive part of a mining operation receives much scrutiny by cost controllers, CEO’s, investors and others as the mining industry goes “back to basics” to reverse the decline in productivity which occurred during the mining super cycle.

Jan 1, 2019

By Richard Turnbull

Maules Creek mine is an open cut coal near Boggabri in the Gunnedah Basin of New South Wales, Australia. The mine is currently operating at an annualised run rate of 9.5Mt of saleable coal. The plan is to ramp up production to 13Mtpa. Maules Creek has multiple seams each with varying depths; the inter-burden ranges from a few metres thick to greater than 30m (98ft). Due to this, Maules Creek mine is utilising truck shovel operations rather than a cast/dozer push operation.

Jan 1, 2018

By Romel Villanueva, Juan Vasquez

We present the results of our field research on the variation of the density of the gassed explosives and their influence on the blasting results in the Peruvian mines: Yanacocha, Toquepala and Antamina. Currently, 90% of Peruvian mines uses gassed explosives, for their economic and technical benefits. But new practices and design criteria have had to be adopted, and the most important a careful control of the in-hole density, whose variation in the depth of the hole strongly affects the detonation process. For gassed explosives the density varies gradually according to the depth in the hole, due to the pressure on the bubbles by its own weight. The density at the bottom of the hole can reach critical values, which directly affects the start of the detonation in the booster zone with a high probability of nitrous fumes formation. On the other hand, density translates into the amount of explosive and energy available. Therefore, for the optimum performance of the explosive, the minimum and maximum values of the in-hole density must be determined. For the cases studied, the maximum in-hole density and the maximum charge length have been determined. When the charge length is greater than 7.0 m [ 23 ft.] special care must be taken with the cup density, which as a general rule should not exceed the value of 1.15 g/cm3 [71.8 lb/ft3] at the risk of losing the sensitivity at the bottom, also increasing the probability of nitrous fumes, bad fragmentation and finding intact explosive after blasting. In the large holes in Toquepala and Antamina mines, where the charge length can be greater than 9.0 m [29.53 ft]. If the cup density is greater than 1.15 g/cm3 [71.8 lb/ft3] the in-hole density can easily reach a high value of 1.30 g/cm3 [81.16 lb/ft3].

By P J. Dailey, S L. Burchell, R F. Chiappetta

High-speed motion picture photography and its application to the mining, quarry, construction, and explosive industries has proven to be a valuable diagnostic tool. The techniques developed allow one to evaluate blasting performance, compare explosive efficiencies in relation to burden velocity, and estimate optimum delay times to provide adequate forward relief.

Jan 1, 1983

By Tyler Rockley, Greg Bailey

This paper is an engineering case study of a blast performed on a highly weathered sandstone isthmus in an area sensitive to vibration and airblast, the challenges associated with such a blast, the methods used to understand rock characteristics, the blast design considerations and a discussion of the blast results. The purpose of the blast was to remove approximately 12 feet (3.7 m) of surface material in order to install a pumping station. The isthmus provided several challenges due to the weathering of the rock and multiple open faces with surrounding water. The highly fractured and weathered rock was subject to about ten years of freeze thaw cycles, influx of water and seasonal submersion. As such, all actual rock conditions were indefinite, including fracturing, rock properties, degradation and competency. The isthmus also had immediate neighbors who were unused to the environmental effects of blasting. To help continue to keep the social license to operate in the area, it was important to reduce the ground vibration, blast duration, dust and airblast. These factors required a better understanding of how the rock would respond to blasting. In order to do this, test blasts were performed on the same geologic formation in a different location of the quarry that was less sensitive to vibration and airblast effects, allowing the blast parameters and design to be verified and refined. The test blasts were performed while monitoring vibration, air blast, material movement and overall shot performance, and the blasting parameters were adjusted accordingly. The isthmus blast was performed based on the final design from these test blasts. The drilling and loading of the shot all met acceptable criteria and were comparable to the test blasts. The blast performance, however, was not as expected; the depth impacted by the blast was substantially more than expected. Since the test blasts were performed in the same formation, but in material that was significantly less weathered than the isthmus, the actual effect of this weathering was the only difference between test blasting and the isthmus blast. Thus, these results can be used for future reference to highlight the effects of blasting such highly weathered rock and help instruct the blast design in similarly complex conditions.

By Mauritz Kotze, Jason Furtney, Ewan Sellers, Sandy Etchells, Tom Szendrei

The development of a simple model for gas flow and burden movement has driven the need to improve our understanding of burden breakage mechanisms for single hole blasts and the interaction between multiple holes in solid and jointed rock masses. Conventional analytical understandings of the burden breakout using the elastic-tensile fracture model were studied and found to provide a breakout angle that is independent of burden in contradiction to experimental data. By considering rock fracture in terms of Mohr-Coulomb plasticity using analytical expressions from the field of cavity expansion analysis an improved relationship between breakout angle and burden is derived until the point of critical breakout at which the angle of breakout suddenly changes from between 90 degree and 100 degrees to zero. This suggests that the critical burden occurs at about 0.6 times the radial fracture zone calculated from the analytical solutions.

Jan 1, 2013