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By J. -P. Tshibangu, E. Lefebvre

ABSTRACT : The Tournai’s region in Belgium is characterized by outcrops of limestone that were mined out long ago by different companies for cement and crushed materials. The region is densely populated and the vibrations generated by blasts in the quarries are of big concern. The occurrence of electronic detonators and development of computer sciences brought a new expectation in controlling the vibration level and, hence, carry out bigger blast operations. In this paper we present the results of two experimental blast programs that have been carried out by the Nobel explosive Belgium Company on the Gaurain-Ramecroix quarry to understand the effect of the delay on the vibrations generated in the neighborhood. The first program has been implemented during the early use of electronic caps in Belgium (1996) by performing some unit shots. An attempt to model the effect of the production blasts by the hybrid method (Hinzen 1988) gave promising but poor results compared to infield measurements. A new program (more than ten blasts) has been implemented in 2006 in which the delay and blast firing sequence (i.e. the order in firing adjacent holes in a row) have been changed; a new attempt is made to build unit signals by deconvolution and then try to model production ones. A comparison of the two approaches is made.

Jan 1, 2008

By Lee Wehner, Daryl Kin, John Bolger

The Maumee Quarry, located in the city of Maumee, Ohio, has large in-situ cavities, ranging in size from 3 ft (.91 m) in diameter to over 15 ft (4.5 m). The drill/blast team challenge is to drill, load and shoot the geologically disturbed rock in a safe, cost efficient manner, while in close proximity to a commercial area. A continuous improvement process, managed by a Blast Optimization Team (BOT), was implemented to quantify the innovative explosive loading techniques that have been implemented. Borehole camera monitoring, modified loading practices, the need for accurate drill hole logging and open communications between the drill and blast crew proves critical to the success of the operation. Safe Standard Operating Procedures (SSOPs) have been developed and are strictly enforced for the drill/blast cycle. All blasts are monitored with seismographs and recorded on video to provide detailed information as part of the Blast Management Plan. Despite the geological challenges, the measurement of rock fragmentation index versus loader dig rates has provided near optimal crusher throughput.

Jan 1, 2007

By Alain Duchesne, Dominique Fonfrede, Alan Broca

The technique involves the removal, in one piece, of an unwanted concrete pile section, exploiting the principle of crack propagation induced using gas pressure. The device, or pod, is made of a container in which an over-pressure is generated. After a predetermined time delay of 72 hours, gas and pressure are produced by the reaction between a calcium base chemical and water.

Jan 1, 2012

By Yoshihiro Moriyama, Toshihiro Okitsu, Ryouichi Banno

The fracturing composition using the gas pressure generated by the thermit decomposition reaction gives the following performances.

Jan 1, 1995

By Lewis L. Oriard

This paper describes the process of developing blasting specifications for 850 miles of new pipe trench running parallel to an existing high-pressure gas pipeline, often with as little as 14 ft to the existing pipeline trench. The primary method of preventing damage to the existing pipeline was the use of fracture (overbreak) control.

Jan 1, 1994

By John M. Bolger, Keith E. McMaster

Excessive salt fines are undesirable in underground salt mining as they are considered a costly waste by-product. This paper describes an extensive explosive application program conducted at The Canadian Salt Company Ltd, located in Pugwash, Nova Scotia, Canada. The prime objective of the program was to reduce the quantity of fines generated from this company's underground production blasts. The program was known as the "The Fines Reduction Program".

Jan 1, 1996

By Paul E. Thompson

Current magazine regulations are designed to avoid injury or property damage caused by accidental detonation as well as to store explosives securely. The primary emphasis appears to be the avoidance of unintended detonation or in the event such detonation occurs, the avoidance of damage to surrounding property. Adherence to these regulations largely serves the purpose intended but has caused difficulty in magazine sitting in built up areas. To the extent that magazine siting is too heavily restricted, other more significant dangers such as storage of explosives in more dangerous and less secure places may be encouraged. In summary, the regulations have served rural magazine locations well but may need further study for urban settings.

Jan 1, 1990

By Murray B. Lytle

The Fording River Operations of Fording Coal Ltd. in southeastern British Columbia is producing 45 million long tons of clean metallurgical coal for shipment to the Japanese steel industry on a 15 year contract. The mine employs conventional truck/shovel operations as well as a walking dragline to mine coal in two mining areas. The coal is processed by conventional means to produce 3.0 million long tons per year of medium volatile coking coal.

Jan 1, 1978

By Otto E. Jr Crenwelge, Timothy A. Peterson

We have developed a site-specific method for analysis, prediction, and control of ground vibrations induced by overburden blasting operations in surface coal mines. Field tests conducted at R&F Coal Company have verified our approach for obtaining signatures of the overburden vibration characteristics at locations of interest near the mine, selecting the optimum excitation frequency for minimizing vibrations, measuring and synthesizing multiple-charge excitation signals for minimizing vibration amplitude and duration and controlling frequency, accurately predicting the multiple-charge vibration response in both the time and frequency domains, and accurately controlling the blast detonation to achieve the predicted vibration control. Initial field studies also indicate that by minimizing the vibrational energy radiated from the blast zone, and by optimizing the number of charges detonated per delay period as allowed by this technique, more effective use of the explosive energy is obtained within the blast zone itself for improving overburden fragmentation, swell, and cast. In all of the phases of this technique, including actual blast detonation, personal computer hardware and software have been verified for use in either field or office environments.

Jan 1, 1986

By Michael S. Wieland

Underground coal-mine explosives (permissibles) can be substantially degraded by the underground stress waves from the explosion of neighboring borehole charges. This cross-borehole interaction generally yields the worst receptor (impacted) charge performance when the borehole separations are too close. For explosives which recover, the receptor degradation is worst when the delay until firing is small. Except for a poor quality muck pile or unreacted cartridge fragments, degraded charge malfunctions of this type are difficult to detect in coal-mine delay blasting. A simulator which reproduces the underground wave/receptor charge interaction and special underwater donor/receptor tests were utilized to study this transient desensitization problem. Test results revealed reductions in receptor energy output, delayed transitions into detonation, inferior reaction rates, or sympathetic reaction responses from the impaction. Tests on detonators showed reduced tip-strength, abnormal functioning times, or sympathetic firing as a result of transient impaction. The cross-borehole desensitization and sympathetic reaction response problems warrant concern because they are logical mechanisms for raising the risk of hazardous mining conditions, including blown-out shots, flyrock, charge deflagration, and methane/coal dust ignitions.

Jan 1, 1987

By A K. Raina, P B. Chourdhury

Flyrock is the unwanted throw of rock fragments to excessive distances in opencast blasting. The incidence is relative in nature incorporating the distance of objects of concern like structures within and outside the mine, equipment within the mine & near the blast and persons within and off the mine. Several attempts to predict and defi ne fl yrock made worldwide could not address the problem since the phenomenon is not a regular feature in blasting. This probabilistic nature of fl yrock allows for risk calculation. CIMFR, India developed a Factor of Safety based risk criterion (10, 14) for evaluation of throw/ fl yrock in opencast mines that incorporates all the above in terms of distance and allowable limit of throw – which in turn determines the risk. The criterion provides the blaster a tool for mathematical evaluation of fl yrock risk in terms of a Factor of Safety and threat ratio (defi ned for the 1st time), thereby enhancing confidence when blasting. The method is easy to use and has been applied to several mines in India and the results are signifi cant. This paper details the evolution of the concept and its application in three limestone mines of India and the results obtained. The application of the method for defi ning a fl exible danger zone is also discussed.

Jan 1, 2008

By Graeme Exelby

The 4" Wassara water hammer was originally developed by G-Drill AB together with Swedish Mining Company LKAB for their underground long hole production drilling. Sandvik Rock Tools AB is responsible for the introduction of Wassara worldwide.

Jan 1, 1998

By John R. Coulson

A survey of federal and state licensing requirements for blasters employed on the surface and underground was conducted for the Bureau of Mines. Subdivisions include surface and underground (large and small), metal, nonmetal and coal. The requirements for certification, class of license, available training, types of testing and enforcement practices are discussed. Included are recommendations of some of the industry trade organizations.

Jan 1, 1980

Increasingly specialized blasting needs require that the explosive energy available in a borehole be reliably known for representative blasting conditions. The underwater test, when properly performed, can yield such information and thus provide a reliable rating of explosives in terms of energy release. This paper reiterates the stringent experimental conditions to be satisfied, and data analysis and interpretation techniques to be followed to achieve this. This is supported by detailed experimental studies involving select parameters in both detonator and booster sensitive explosive compositions. The paper also illustrates the inadvisability of equating blasting performance with the commonly calculated energy values.

Jan 1, 2000

By Raymond V. Adolphson

The introduction of a new explosive component in 1955-56, called ANFO, featured much safer, effective blasting characteristics when compared to dynamite, accompanied by a notable reduction in cost. These savings mounted as borehole diameter or depth was increased with ANFO volume subsequently enlarged.

Jan 1, 1983

By Koichi Kurokawa, Takeo Ueda, Yoji Tasaki, Masashi Nakano

We have developed a new firing system which simplifies the handling and extensively increases the safety in electric blasting operations. Based on the principle of the transformer, this system is operated as follows: When a high frequency alternating current pulse (70-110 kHz) is applied to the lead wire and connecting wire (primary circuit), magnetic flux is generated in the transcore, and an induced current flows through the looped leg wire of the detonator (secondary circuit). Then the detonators are ignited by the induced current.

Jan 1, 1986

By Thomas R. Scotese, John L. Ackerman

The Hanging Lake Tunnel Project represents a major portion of the Glenwood Canyon Project, the last piece of Interstate 70 to be constructed. The project features twin bore, large span rock tunnels and six open cut portal excavations, all excavated by drilling and blasting. This paper presents descriptions of the methods used by the Owner and Engineer to control and monitor the drilling and blasting practices in the tunnels and in the portal areas.

Jan 1, 1992

By Kis M

The purpose of seismic control of blasting is to indicate the vibration magnitude or to eliminate the occurrence of vibration damage caused by blasting. At the Mining Research Institute in Hungary, a new method has been developed to determine the method of delay. Near the blasting site (within 100-200 meters), the peak value of the particle velocity is determined by calculation and also by measurement. In the calculations, the time error of the electric detonators is taken into consideration. During the test program, the results of the experimental blasts and the calculated data have shown good correlation. The method of calculation helps the operator eliminate vibration damage, while the greatest quantity of charge can be detonated.

Jan 1, 1979

By Cathy Aimone-Martin

The City of Henderson, Nevada is experiencing extraordinary population growth. Some residential development requires blasting to be conducted at close proximities to high-value houses. Blastingrelated concerns voiced by the community residents include dust, noise, fears of damage to residences, and claims of insufficient controls exercised by the blasters. Residents perceive geological conditions are adverse to the protection of structures at the current vibration regulatory limit of 0.5 in/s. Airblast limits are 120 dB. Vibrations felt within structures leave home owners with the perception that damage is taking place. New cracks appearing in homes at distances far from the blasting are being blamed on blasting.

Jan 1, 2007

By Rodney C. Espley-Jones, John C. B Wilson

South Africa is well known for its shaft sinking exploits, and many of the world's biggest and deepest shafts are to be found there. Blasting practice differs in a number of respects from that followed elsewhere.

Jan 1, 1979