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Fracture Control Blasting is an alternative to pre- and post-splitting or smooth wall blasting. It was developed at the University of Maryland as an attempt to overcome some of the disadvantages that occur with normal blasting practices. There are two main factors that are unique to fracture control blasting. First, it utilizes a notched or grooved borehole to initiate fractures at desired locations and secondly, it employs a very carefully selected charge so as to provide control over borehole pressure. The maximum borehole pressure must be kept between very definite limits in order to obtain initiation of fractures at locations where they are desired and yet not obtain fractures where they are not desired. When coupled with stem induced fracturing, which was developed for oil and gas well stimulation, it has been found that the charge required for fracture control can be as little as 1/40th that required for normal smooth wall blasting. The paper describes the technique of fracture control blasting and gives results of some of the field testing conducted to date.

Jan 1, 1984

By Agus Setiabudi

East Pit Wira II Project in South Kalimantan, Indonesia with a radius of <500 meters (1,640 ft) from residential has about 454,168 tonnes of coal reserves, with a total remaining reserves of 3,369,383 tonnes (topography per end of June 2011). Thus, reserves may be lost as much as 13.48%. Therefore, it is needed to determine safe blasting technique which meets the Indonesian National Standards (SNI) No. 7571:2012 of vibration threshold, the maximum vibration of 3 mm/s (0.118 in/s) and air blast of 120 dB.

Jan 1, 2014

By J J. Mullay, G W. Anderson, C J. McFinley, J F. VanNorman, C J. Kefer

Previous work has shown that testing of precompression effects conducted on a small scale under simulated field conditions in actual rock provides a reasonable model for the evaluation of explosives and initiators under the adverse conditions encountered in production blasting. Using this methodology can result in greater understanding of the phenomena as well as the ability to predict performance. This effort has been extended to evaluate various parameters not previously studied in a controlled fashion. The present paper describes the use of this technique to study the effects of delay timing on precompression effects. Intervals from 25 to 150 milliseconds are included in the study. Both VOD measurements and damage estimates are utilized in the evaluation. The results demonstrate that timing delay between holes is quite important in determining the overall effectiveness of a blasting program.

Jan 1, 1994

By Navid Mojtabai, Jaak J. K Daemen

Some facilities require ground vibration limits that are far below typical vibration levels of interest in most blasting situations. A possibly extreme example of such a facility might be the proposed SSC (Supercollider Super Conductor) high energy particle study system. The applicability of conventional blast vibration predictors for such a low amplitude vibration is highly uncertain. For this preliminary study, a series of field measurements are made, and the results integrated in a set of vibration predictor equations. Ground vibrations induced by blasting operations at one proposed SSC site are monitored at close distances (hundreds of feet), intermediate distances (miles), and long distances (tens of miles) from the blasts. Peak particle velocities are recorded at short distances, ground displacements at other points, as well as frequencies. Theoretical analyses are performed by integrating all data in a variety of ground vibration predictors. From the statistical analysis of the data, ground motions at various points along the ring site are predicted for a given charge weight. The approach taken appears adequate for making tentative estimates of exceedingly low amplitude vibrations at great distances from mine blasts.

Jan 1, 1987

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 Elaine Gorham-Bergeron

CAROM is a distinct element, dynamic code developed at Sandia National Laboratories to calculate the motion of rock fragments during blasting.[1] It has recently been improved to incorporate a mechanism for its elements to mimic non-circular rock fragments. With this option, elements stack and move in ways that are characteristic of irregular boulders of blasted rock. In bench geometry, CAROM has been used to examine the possibility of producing variations in muckpile shape due to variations in detonation-time delays between rows. Surprisingly, the shape of the muckpile was predicted to be insensitive to time delays between detonation of rows of explosive, except where the rock fracturing was affected by the time delays.

Jan 1, 1987

By D Reid Watson

A unique blend of theory and hands-on teaching of blast hole drilling and explosives technology is being provided at a Canadian Community College. Students graduate at an apprentice level quite capable of operating and maintaining blast hole drills and designing and executing surface blasts.

Jan 1, 1987

By Richard J. Mainiero, T S. Bajpayee

The Bureau of Mines, U.S. Department of the Interior, has developed test procedures and criteria for evaluating explosive reactivity of explosive contaminated solid waste substances generated by U.S. Army Ammunition Plants. These substances are produced as explosive-contaminated sludge from waste water treatment plants, residues from the burning of munitions and explosives on open ground, and residues from deactivation furnaces. The characterization of explosive reactivity is a prerequisite for disposal of such waste materials, which may be contaminated with primary explosives, propellants, or pyrotechnic materials. The Bureau has proposed two tests for this purpose. These tests were developed to evaluate the explosive reactivity as defined in Title 40, Code of Federal Regulations, Part 261.23(a)(6) and (7). These are Bureau of Mines Gap and Bureau of Mines Internal Ignition tests, which determine the sensitivity to shock and thermal stimuli, respectively. This paper also includes gap and internal ignition reference data for typical blasting agents, high explosives, propellants, and marginally reactive substances. These reference data were used to establish test criteria. The Bureau has evaluated over 400 samples of contaminated soil, sludge, and burning residues using these two test methods.

Jan 1, 1988

By Bradley C. Paul

Similar rock formations exhibit great variability in resistance to fragmentation during crater blasting. This observation was made during an attempt to calibrate the Kuz-Ram blast fragmentation model for crater blast geometries used in a modified in situ mining method for copper. The KuzRam equation is used to predict the fragment size distribution from blasting and includes a term called the "rock factor" to account for the fragmentation characteristics of the material. A data base of field scale crater shots in oil shale was available to supplement more limited data on copper ores. First, the blast geometry terms of the Kuz-Ram formula were modified to fit field data with various crater blast geometries. Rock factors were chosen to center the predicted curve on the curve representing observed fragmentation. Next, five possible sources of variability in rock factor were investigated: the grade of the oil shale, the aspect ratio of the charge, the type of explosive, the charge depth, and the rock itself.

Jan 1, 1989

By Gungor Tuncer, Ali Kahriman, Abdulkadir Karadogan, Savas Gorgun

The principal disturbances created by blasting in open pit mines are vibrations, air blast and fly rock. All of them, under some circumstances, caused damage to structures nearby and apart from this can be the source of permanent conflict with the inhabitations who live close to the operation. Therefore, prediction of ground vibration components is of great importance for the minimisation of the environmental complaints. This paper presents the result of ground vibration measurements induced by bench blasting realised at Can Open Pit Coal Mine located close to the residential area of Can town. Within the scope of this study, in order to predict peak particle velocity and determine the slope of the attenuation curve for this site, ground vibration components were measured for blast events during bench blast optimisation studies over a long period. During the study, while the parameters of scaled distance were recorded carefully, the ground vibration components were measured by means of two different types vibration monitors (White Mini-Seis and Instantel Minimate Plus Model) for 54 blast events. At the end of evaluation an empirical relationship with reasonable correlation was established between peak particle velocity and scaled distance for this site.

Jan 1, 2001

By Bill Paysse, Lyle Ruffle

My intention is to produce a video, pictorial, and oral presentation on utility blasting, primarily power pole holes and ditches. Included will be blasting for a take-off structure inside of Wanapum substation, jointly owned by BPA, PSE, and Seattle City Light, and blasting for 230kV steel tower foundations.

Jan 1, 2007

By Huang Fenglei, Jin Qiankun

A new linear charge method has been applied in coyote blasting for highway excavation in which presplitting boreholes are set along the designed rock slope with some empty chambers at the end of linear charges whose axes are perpendicular to the axis of the highway. Three-dimensional nonlinear finite element analysis for this method has been conducted using LS-DYNA3D. The results indicate that the blasting damage to the rock slope is reduced greatly using the new linear charge method in coyote blasting.

Jan 1, 1998

By Guillermo Silva

A novel, ultra-low density explosive composition, particularly suited for wall control and other applications requiring customising of the explosive’s energy output, has been developed. Being reactive in nature, the low density explosive enables the controlled dilution of dry blasting agents from their nominal densities down to values slightly less than 0.10 g/cm3. The product has been detonated at densities of 0.07 g/cm3 in diameters as small as 50mm under confined conditions, using a 227 g (l/2 lb.) primer. Recorded velocities of detonation ranged between 1200 m/set and 2200 m/set for densities between 0.07 and 0.2 g/cm3. Theoretical velocities ranged from 1700 m/s to 2500 m/s for the same density range. The low density explosive was insensitive to initiation by a blasting cap which is a desirable feature for transportation purposes. Mixing of the product with ANFO has been accomplished with minimum segregation making it suitable for applications where reduction of pressures are necessary.

Jan 1, 2000

By Dave I. McGregor

The Multiple Raise Round Blasting Technique (MRRBT) is a safe, efficient, cost effective method of blasting thee will use existing mine personnel. The MRRBT, developed from the conventional 'drop raise method' style of blasting, can be used for most raise mining applications. Current results using MRRBT indicate no upper limit for the maximum length that a raise can be blasted.

Jan 1, 1994

By Don Houston

Vertical crater retreat mining (VCR) requires initiation methods that minimize debris in the borehole. The use of detonating cord and shock tube detonators eliminates debris that could interfere with subsequent loading operations and avoids the cost of using drilling equipment to clear the debris. The explosive must not be sensitive to the strength of detonating cord used, otherwise timing will be affected. “Slicing and Dicing” of product before “Air mailing” down boreholes may facilitate loading, especially in wet holes, and can result in product surrounding the detonating cord. Cord sensitivity testing confirmed that having the detonating cord surrounded by product significantly increases the likelihood of an energetic reaction. Careful formulation and testing, based on a thorough knowledge of the application and the role of ingredients in affecting performance, ensures reliable initiation and avoids cord sensitivity. The use of certain metallic nitrate salts, even in relatively small amounts, was found to significantly increase the cord sensitivity of watergel formulations. Evidence of increasing cord sensitivity includes increasing amounts of damage to product and packaging, to ejection of product from the test pipe, then cracking of the pipe, followed by deflagration then detonation of the product. Predictably, the likelihood of an energetic reaction increases with product temperature, cord strength, and borehole diameter, while it is inversely related to product density.

Jan 1, 2002

By C Yeung, G Fitz, R Heater, P D. Katsabanis

Explosives malfunction due to shock waves is a serious concern for successful blasting results. Malfunction can range from sympathetic detonation to desensitization and modification of firing times of conventional pyrotechnic detonators.

Jan 1, 1994

By Robert Martin, Brian W. Stump

As part of a series of seismic experiments designed to improve the understanding of the impact of mining blasts on verifying a Comprehensive Test Ban Treaty, a sixteen station network of three-component seismic sensors were deployed around a large cast shot in the Black Thunder Mine. The seismic stations were placed, where possible, at a range of 2.5 kilometers with a constant inter-station spacing of 22.5 degrees. All of the data were recorded with the seismometers oriented such that the radial component pointed to the middle point of the approximately 2 kilometer long shot. High quality data were recorded at each station. Data were scaled to a range of 2.5 kilometers and the sum of the absolute value of the vertical, radial, and transverse channels computed. These observations were used to construct radiation patterns of the seismic energy propagating from the cast shot. It is obvious that cast shots do not radiate seismic energy isotropically. Most of the vertical motion occurs behind the highwall while radial and transverse components of motion are enhanced in directions parallel to the highwall.

Jan 1, 1997

By Greg J. Stach, Norman "Skip" Hale

The authors describe the development of an overburden blast casting program in the upper seam of coal at a 2-seam surface mining operation on property adjacent to an active operating underground coal mine. Control of vibration is essential.

Jan 1, 1984

By Bob de Raadt

For a long time industrial underwater blasting has stood in need of a calculation method, for the determination of shockwave-proof as well as shockwave-effective charge distances to objects in water. After a brief discussion of the physical background of the shockwave mechanism in water, the author discusses an empirical theoretical computing method based on the "Bubble boundary" concept. The practical application of this model is finally shown in an account of a few underwater blasting operations in which charge weights of c.1-1000 kg were involved.

Jan 1, 1980

By A T. Spathis, J J. Felice, W Klass

Cast blasting has become one of the most efficient ways to move waste rock in open cut coal mining. It is used at Mount Thorley Mine in conjunction with a dragline to move some of the overburden onto the spoil dump.

Jan 1, 1992