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By J W. Edl, F C. Wu

In instrumented model rock blasting experiments in granite blocks, best fragmentation results were obtained when delays between holes were 1 to 2 milliseconds per ft. of burden and when a rectangular shothole pattern was used with spacings larger than the burden. Effective fragmentation in multiple hole blasts seemed to depend primarily on the full development of the crack network around each hole before the charge in the next hole was detonated. The test results showed that simultaneous or almost simultaneous initiation of shotholes in bench blasting resulted in poor fragmentation.

Jan 1, 1975

By Kaby K. Kabongo

The paper is drawn from a project intended to explore a technique of prediction, control and optimization of fracture in coal induced by blasting. It evaluates the fines generated in coal submitted to dynamic loading stresses in an impact stamp mortar. The aim is to analyze a complex phenomenon of coal response to blast-generated stresses from a series of discrete simulations of shock and gas actions in controllable processes.

Jan 1, 1995

By Mark S. Stagg, Steven V. Crum

The Bureau of Mines is conducting research to develop methods to control fragmentation and improve productivity in surface mine blasting. As part of this research, PRONT02D, a two-dimensional finite element computer program developed at Sandia National Laboratories, was employed to model the fragmentation produced from RS-50, a single hole, reduced scale bench blast in a massive dolomite. The fragment size distribution obtained from the computer simulation was calculated using a submodel that utilizes the crack density and nominal flaw size values computed by PRONT02D.

Jan 1, 1989

By Calvin J. Konya

There have been many different brands of high precision caps introduced on the US market in the last five years. High precision timing definitely effects the performance of the blast. One should be able to optimize fragmentation and minimize environmental effects with the use of high precision caps and selection of the proper time period. The consumer who purchases the caps may not be fully aware of the tolerances in firing times of caps used in the field. This paper will discuss results of field tests of cap tolerances from an independent study conducted by Precision Blasting Services.

Jan 1, 1989

By G Alan Foster

Many complaints generated from blasting operations result from the marked human response to ground transmitted vibrations and air blast effects and so many authorities have considered the regulation of blasting in terms of human response rather than, as previously, in terms of preventing damage to structures.

Jan 1, 1981

By Kunihisa Katsuyama, Yuji Ogata, Takuya Taguchi, Toshinori Arikiri, Yuji Wada, Kiyoshi Hashizume

The impact sensitivity of hot emulsion matrices was examined to investigate the safety assessment in the emulsifying equipment which forms the emulsion matrix in a water-in-oil type emulsion explosive. The sensitivity could not be evaluated by the small fallhammer test device commonly used in Japan. Therefore, a large fallhammer test device was used. It was confirmed that an explosion, a decomposition, or a no-reaction took place according to the degree of the impact. When a decomposition took place in the hot emulsion matrix, the behavior of it was investigated further by a DDT test. It was found that a decomposition, or a no-reaction occurred according to the degree of confinement.

Jan 1, 1997

By Virgil L. Lewis

On September 7, 1994, a Burlington Northern coal train crashed into a parked train in the downtown Gillette, Wyoming rail yard. I would like to address two issues in regards to this accident. One, a slide presentation of the damage created by the accident and the resulting required clean-up and two, a simulation of "what if" had there been an explosion during the course of the crash.

Jan 1, 1996

By Sarma Kanchibotla

In mineral industry operations the insitu ore is’separated from the waste rock and is subjected to a series ofprocesses to convert it into a valuable product. Profitability of any operation in this industry depends on how eficiently the insitu rock (ore -I- waste) is converted in to the final product and how much value @ice) it commands in the market. Traditionally, the total process in mineral industry is classt@ed into two groups as mining and milling, and optimised independently without considering the impact of one over the other. This paper investigates the impact of mining operations (especially blasting;) on downstream processes and demonstrates the potential benefits of the “Mine - Mill Blasting” approach through simulations and case histories.

Jan 1, 2000

By Carlos Agreda

"It is widely accepted that the rock blasting results are a function of several stochastic variables given by: -The natural geological structure of the rock mass (joint spacings, discontinuities length orientation and characteristics, physical-mechanical properties, such as: ultimate strengths and elastic properties, etc.).-The detonation and explosion parameters of the explosive mixture (V.O.D., P2, T2, Q3, etc.).-The drilling and blasting pattern dimensions.-In this paper the most important stochastic variables regarding with the rock mass and the blast design dimensions before mentioned are identified, described and discussed.A non linear programming method to calculate the optimum burden Bo) is proposed and discussed.The great impact of the stochastic variable called burden (B) on the rock blasting results is emphasized. A comparison between burden theoretical calculations and some field blast results is also shown."

Jan 1, 1996

By E Castelli, M Fomaro, R Mancini, M Cardu

The economic return of rock blasting is not provided by brute volume of broken rock, rather by the amount of marketable product. That is the case of the porphyry quarries of Trento district, whose output is mainly absorbed by road paving and building facing elements production.

Jan 1, 1995

By Virgil J. Stachura, Calvin L. Cumerlato

The Bureau of Mines conducted a series of tests to develop a blasting method that would reduce overbreak and rockfall hazards at a limestone quarry in northeastern Wisconsin. Reductions in overbreak were achieved by shortening the main explosive column and reducing the explosive load in shortened stemming zones in shotholes which were to form the highwalls. Two blasthole diameters, 3 and 4 inches, were used with 7 by 7 foot and 9 by 12 foot burdens and spacings respectively. ANFO, Comsol 300, or PowerAN were used in the body of the shots and Gelmax or 40 pct extra dynamite cartridges were used in the reduced load zones. Smoother highwalls were visually apparent, however further analysis by seismic refraction techniques were performed as an aid to studying overbreak within the rock mass.

Jan 1, 1989

By Kirlk Yeager

"Ammonium nitrate (AN) is commonly mixed with a wide variety of additives to produce specialty formulations. Two additives commonly utilized are sodium nitrate (SN) and sodium nitrite (SNi). Application of the nitrite is primarily limited to gassing of emulsions. The nitrate, however, is incorporated in a wide variety of formulations. The effect of both these materials on the thermal stability of AN was examined. Experiments initially utilized lab-scale testing methods (sub-milligram sample size), such as differential scanning calorimetry (DSC), with scale-up to cook-off analyses (16 g) eventually applied. Labscale testing indicated that the presence of SN and SNi (both at 5 wt%) produced no harmful effects on the thermal stability of AN. The cook-off results did not agree with those from the lab-scale analyses, with both SN and SNi creating tremendous thermal destabilization of AN. These effects were seen at additive levels as low as 0.1 wt%. When SNi was employed as the additive, cook-offs became violent enough to create explosions in the testing apparatus. Although SN did not create as spectacular a destabilization, it did lower cook-off temperatures to approximately the same level as SNi. The dangerous situation created by SN andSNi seemed to be limited to cook-offs conducted in sealed vessels. If the SN/AN or SNi/AN formulations were allowed to cook-off in vented vessels, the thermal destabilization of AN did not occur. These results seemed to indicate that even “trace” amounts of what might ordinarily be viewed as benign additives could create significant destabilization of AN-based explosives under proper circumstances. Conditions created by blocked pumps, or deep boreholes could well overlap those produced in sealed cook-off vessels. In addition to showing the hazards potentially created by “benign” additives, the study also stressed that experiments designed to evaluate thermal hazards must include duplication of field variables to the fullest extent possible. "

Jan 1, 1999

By T S. Bajpayee, Thomas C. Ruhe

"The Pittsburgh Research Laboratory of NIOSH conducted research to determine the safe operatingconditions for using recycled (used) lubricating oil from mining equipment as a partial replacement for diesel fuel to make ANFO-type blasting agents. The use of recycled oil (RO) conserves energy, reduces oil imports, and reduces mining costs."

Jan 1, 1999

By Dennis Dobson, Keith M. Henderson

Lone Star Industries, Inc. in Cape Girardeau, Missouri operates an open pit mine to produce limestone for its portland cement manufacturing plant. The present mining method, for safety and legal reasons, requires a set back from the property line, a berm, sloped overburden, and vertical rock walls with catch benches.

Jan 1, 1997

By P. D. Lightfoot, C. Badeen, R. Turcotte, D. E. C. Jones

Following localized (i.e. hot-spot) ignition, there is a minimum pressure required for combustion to propagate in water-based commercial explosives. The latter is usually referred to as the ‘Minimum Burning Pressure’ (MBP) of the explosive. In the present work, both an apparatus based on hot-wire ignition and an associated methodology were developed to measure the MBP of water-based explosives. It was demonstrated that the MBP constitutes a sharp pressure threshold below which the probability of inducing sustained burning in these explosives becomes very small. It was found that each emulsion explosive tested has a distinct MBP value, which depends critically on its formulation. It appears that this test may offer a firm basis for the classification of emulsion explosives for regulatory purposes.

Jan 1, 2004

By Ali Kahriman

This paper presents the results of ground vibration and air blast measurements from tunnel blasting activities during the construction of the Beylerbeyi-Kucuksu waste water tunnel under a residential area in Istanbul, Turkey. Within the scope of the study, the blasting pattern of the tunnel was engineered using Tunnel2000 design software and field studies and measurements for evaluating the productivity and safety of shots were realized for 136 rounds. During the study, the advance of the tunnel, face condition, ground vibration, air blast and neighbours’ complains and comments after every round were observed and the tunnel pattern was improved. Finally, an empirical relation for this tunnel route was developed between scaled distance and maximum amount of explosives, to continue activities in a safe and productive manner.

Jan 1, 2006

By Magnus Gynnemo

The primary purposes of drilling and blasting in hard rocks is to fracture solid rock and prepare it for excavation and subsequent transport to the crushing plant. Using explosives in excavation operations without counting for the geology gives no consideration to the quality of the macadam product or the excess production of waste material (fines).

Jan 1, 1997

By Anders Lagerkvist, Agne Rustan, Tommy Edeskar

Landfills containing house hold waste produces methane gas during its decomposition. This gas can be recovered and used for heating purposes or as fuel for vehicles. Gas drainage pipes are installed in the landfill and connected to a central suction point. Methane gas is produced over several years until the slots in the drainage pipes are clogged by black mud. And the bottom of the vertical drainage pipe are filled with mud and water. The hypothesis tested in this paper is if blasting in the drainage pipes could activate the production and flow of methane. In the first part of the paper we have studied what maximum linear charge concentration could be used in different size of PE-pipes place vertical on surface and surrounded by air. The results show that the maximum linear charge concentration for single blasts varied between 5-10 g/m, depending on the diameter of the pipe (90, 100 and 160 mm). Maximum charge concentration for the repeated blast varied between 2-5 g/m. In the second part of the paper we study what maximum linear charge concentration could be used in situ for full scale blasting tests in a special prepared test area which later on was dug out after the blastings. Up to 40 g/m could be used without damaging the top of the 160 mm diameter pipes. The increase in methane flow was so low so it could not be measured c4.5 m3/h. The conclusion therefore is that the stimulation of methane flow by explosives is not enough.

Jan 1, 2000

By Thomas J. Snyder

Modern quarry management should be alert to every opportunity to improve productivity and reduce operating costs. In this paper, the author outlines areas in which explosives suppliers should be encouraged to propose changes. He also supplies guidelines for evaluating these proposals, suggests yardsticks for measurement, and stresses the need to be open-minded when dealing with imaginative, innovative concepts.

Jan 1, 1988

By George P. Jr Schivley

Data is presented showing Penetration Rate (PR) versus Force-on-the Bit (FB) and Bit Angular Speed (N). Using this data, it is shown how FB and N each uniquely contribute to the PR for any particular drilling situation. This data represents many mining situations; including coal, copper, gold, iron ore and limestone quarrying. The important relationship between Penetration per Revolution (P/R) and the height of the cutting elements of the bit (CH) is discussed. Drill performance is then reviewed, considering the effect of FB and N on bit life. All this leads to recommendations for the operating values of FB and N for drilling situations where the rock is not highly abrasive and bit replacements are because of catastrophic failure of the bit cone bearings.

Jan 1, 1995