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By Gungor Tuncer, Ali Kahriman, A. Kadir Karadogan, Savas Gorgun

The environmental problems arisen from ground vibration and air blast have been faced and discussed frequently in various industries such as mining, construction, quarry, pipe line etc. where blasting is unavoidable operation. Structural damage due to ground vibrations creates great socio-economic problems for mine and quarry management as well as for the people residing in its vicinity, therefore in bench blast design, not only the technical and economical aspects, such as block size, uniformity and cost, but also the elimination of environmental problems resulting from ground vibration and air blast should be taken into consideration. With the general trend towards larger blasts in mining and infrastructure excavation, ground vibration and air blast problems and complaints have significantly increased. With increasing environmental constraints on the levels of disturbance induced by blasting operations upon nearby residents, there is an increasing need to be able to design cautious blasting with greater precision, therefore determination of maximum amount of explosive per delay for a certain distance especially in large blasts is of great importance for the elimination of these environmental problems. In another word, prediction of ground vibration components is extremely important for the minimisation of the environmental complaints. Estimating of particle velocity and other components of ground vibration with reliable approaches will give important facilities to the blasters. Although many studies had been carried out to isolate environmental problems induced by blasting in the past, a general reliable formulae has not been established yet. Due to restrictions on the complexity of ground motion, blasting and test site factors, experimental studies are still necessary for each site to minimise environmental issues. This paper presents the results of ground vibration measurements carried out during the excavation activity for contruction of an organised industrial region located nearby Istanbul in Turkey. The major rock type is granite that is encountered at this site. Within the scope of this study, in order to predict peak particle velocity level and produce a site-specific propagation curve for this site, ground vibration components were measured for blast events during bench blast optimization studies over a long period. In blasting operations; ANFO (blasting agent), gelatine dynamite (priming) and delay detonators (firing) were used as explosives. While the parameters of scaled distance (charge quantity per delay and the distance between the shot and the station) were recorded carefully, the ground vibration components were measured by means of two different vibration monitors for every event. Then, the data pairs of scaled distance and particle velocity were analyzed. The equation of scaled distance extensively used in the literature was taken into consideration for the prediction of peak particle velocity. At the end of statical analysis and evaluations an empirical relationship with good correlation was established between peak particle velocity and scale distance for this site.

Jan 1, 2000

By Harry Verakis, Thomas Lobb

This paper summarizes the course of mine blasting safety, particularly in underground coal mining, in the USA for over a century of mining operations. During the late 1800's and especially in the first decade of the 1900's, a large number of mine explosions occurred in which blasting played a significant role. A contributor to the large number of mine explosions during this time period was the use of black blasting powder to extract coal and other minerals. A review is made of some of the more significant underground coal mine explosions that resulted from blasting operations during this time period up to the present day. The safety measures that were adopted and required by a series of laws as a result of mine explosion disasters in which blasting was one of the factors are examined. The time line of historical improvements in blasting safety and the tremendous reduction in fatalities and injuries over a century is illustrated and discussed. The improvements, which included the elimination of black powder and dynamite and the introduction of safer explosives termed "permissibles" occurred slowly over time and culminated from the occurrence of many coal mine explosion disasters. The blasting accident history over the past decade is discussed to show the great gains made when compared to the first decade of the 1900's. The most recent blasting accident fatality that occurred in October 2006 at a U.S. underground coal mine is also discussed. Although the blasting accident record is significantly improved from over a century ago, continual improvement is needed to reach the goal of zero fatalities.

Jan 1, 2009

By N. Paley

An engineering project was undertaken at the Cominco Alaska Red Dog Mine to determine the extent that Semi-Autogenous Grinding (SAG) mill throughput could be increased by blasting differently. The Julius Kruttschnitt Mineral Research Center (JKMRC) blast fragmentation, jaw crusher, and SAG mill breakage models were used to relate changes in the blast design to the SAG mill performance. For optimum performance a SAG mill requires a particular size distribution; a number of large rocks to facilitate breakage by impact, as few as possible middle size rocks that become critical size, and the maximum fines which will pass quickly through an open-circuit mill. Physical constraints of drill and charging equipment size limit the extent that pattern geometry can be changed and the powder factor increased to maximize fines. However, JKMRC research had shown that it appeared possible to increase primary breakage by blasting to such an extent that SAG mill throughput could reach a plateau or even begin to decrease. Modeling was carried out on a range of blast pattern geometries and emulsion explosive blends to determine if a plateau existed and at what powder factor it would be reached. It was found that the relationship between powder factor and grinding throughput was nonlinear. Modeling was also used to compare the SAG mill throughput which could be expected from different emulsion explosive blends to determine which blends should be used in dry and wet holes to provide similar fragmentation. For heavy-ANFO mixtures, the highest modeled throughput was at a ratio of 30/70, with ratios on either side indicating lower throughput. For emulsion blends, the highest modeled throughput was at a ratio of 80/20; however, ratios from 80/20 to lOO/O were similar. Crusher product size distributions were obtained from belt cuts early in the analysis to confirm model predictions. At later stages, actual SAG mill throughput was compared to predicted. The economic benetit from the different blast designs was calculated by accounting for the reduction in recovery due to the higher throughput and the additional drilling and blasting costs. Increasing the powder factor by 150% from the 0.29kg/t {0.58lb/st] being used to 0.72kg/t { 1.44lb/st}, the maximum feasible with mine equipment, could provide a sign&ant net benefit of $3OWyr due to the increased concentrate production. However, because the relationship between throughput and recovery is affected by other factors which were not modeled, a more conservative approach was taken. The powder factor was instead increased by 50°h, providing 45% of the gain. This was possible because the relationship between powder factor and grinding throughput was nonlinear.

Jan 1, 2001

By P. N. Worsey, M. Schmidt

Many advanced military systems and civilian power generation concepts postulate the availability of compact sources of electrical power capable of delivering gigawatts over microsecond time scales. For example, such a compact power source is essential for future practical pulsed high-powered microwave sources. An explosive-driven flux-compression power generator (EDPG) could fill this requirement. A basic strength of this concept capitalizes on the inherent high energy density storage capacity of modern chemical explosives. It relies on the physics of magnetic flux compression to convert that stored chemical energy into very large amounts of electrical power over short time scales. The generator also has the additional advantage of employing the same types of explosives that are already routinely used in conventional munitions. However, the self-destructive nature of this type of power generator places serious limitations on power pulse-lengths and ranges of applications. This paper describes how a multi-disciplinary team led by researchers from the University of Missouri-Rolla (UMR), Texas Tech University (TTU), and Texas A&M University was awarded a grant by the U.S. Air Force Office of Scientific Research to perform basic research to resolve several fundamental EDPG problem areas. Described are the utilization of UMR’s extensive explosives research expertise and facilities to investigate questions of energy conversion efficiency and the mechanics of energy production. Also, UMR explosives researchers will provide inputs to improved dynamic computer models of the complex, intertwined physics and chemistry operative in these devices. In addition to explosives expertise, UMR provides facilities for basic explosives material research, as well as the storage, machining, and formulation of explosives. UMR researchers are also using test facilities and data collection equipment at the Rock Mechanics and Explosives Research Center and at the UMR Experimental Mine to perform “proof of principle” and subscale tests of explosive-driven flux-compression power generator components. An integral part of the paper is a description of the development of an extreme intensity flash system by UMR and TTU to allow for the high-speed photography of EDPGs in operation. This multi disciplinary research program offers major advances regarding the size, weight, and electrical characteristics of compact EPDGs. Such breakthroughs could dramatically accelerate the practical realization of systems currently under study. Also, these power sources may have far reaching relevance to other Department of Defense and certain commercial compact power applications.

Jan 1, 2000

By Dale Ramsey

As someone who has enjoyed photography as a hobby for many years, aerial photography to me has always been an exciting way to give a different perspective to my images. Our industry is always in search of new technology for bet­ter and more cost effective methods to improve our trade and aerial photography is a great tool to improve project planning or document its progress. It has typically involved conventional aircraft both fixed wing and helicopters but neither method is always available or cost effective. The lat­est innovation since digital imaging is the development of Unmanned Aerial Vehicles (UAVs) or drones. But there is a lot of uncertainty with this amazing new technology’s fu­ture in the U.S. as the Federal Aviation Administration (FAA) is under review and development of UAV regulations for commercial use which are slated to be completed in 2015.

Jan 1, 2015

Drilling through unconsolidated material I need to drill blastholes through a mix of consolidated and unconsolidated material. This material is hung up in an underground ore pass. The total length of the holes would be approximately 200 feet. We have attempted to drill through the material with conventional ITH drilling, but were unsuccessful. Does anyone have a suggestion? I am more than willing to bring in a contractor to do the job, if they have solid experience with this type of problem.

Jan 1, 2011