Search Documents

By Alastair Torrance

The performance of commercial explosives is clearly influenced by the conditions under which they are used. Mining companies are supplied with Technical Data Sheets which provide details about explosive properties and its suitable application. These are generally produced using laboratory techniques which may not accurately reflect the quality and performance of the product in the field.

Jan 1, 2013

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

The breakage mechnism of a spherical charge greatly differs from that of the cylindrical charge used in underground mining. The advantages of the spherical charge could not be utilized until INCO Metals Company, Ontario Division, introduced large diameter holes to their operation.

Jan 1, 1978

By Markus Pötsch, Andreas Gaich

Optimization of surface blasting based on 3D models from drone imagery and a closed loop that starts with an automatic analysis of the geometry and the geological conditions and ends with an objective assessment of the blast result.

Feb 1, 2020

By TA Louw, Dr CM Lownds

In an era where profits are constantly being eroded, mines are looking towards technology developments to assist them in solving mining problems and reducing mining costs. An emerging technology that could assist mines in becoming more cost effective is electronic detonators. Electronic detonators have been under development for several years. Over the past three years, the spotlight has fallen on commercial use of electronic detonators and the extent to which the promise of precise and programmable timing can assist mines with their environmental and productivity problems. This paper uses case studies to demonstrate both surface and underground applications where electronic detonators and blasting systems were used to solve typical mining problems such as vibration and fragmentation. Safety aspects such as hanging wall conditions and high wall stability also benefited from the use of electronic detonators. The paper also demonstrates how the use of accurate electronic detonators and blasting systems has resulted in improved/more even fragmentation with further downstream efficiencies. These efficiencies may include increased cast percentages, reduced oversized rocks, quicker cleaning times and increased production rates.

Jan 1, 2004

By Larry Ng, Keith McDonald

The benefits of controlled blasting techniques have gained increasing recognition by the mining industry in recent years. The utilization of an effective controlled blasting programme can result in a safe work environment with less loose rock and a reduced level of scaling and ground support.

Jan 1, 1994

By Scott E. Winston, Spencer C. Watson

Dynamite is a generic term for a variety of high explosive formulations containing a blend of liquid and solid nitrate esters co-mixed with solid oxidizers and carbonaceous fuels. Dynamites can be divided into general classes of nongelatins, semi-gelatins, and gelatins which vary as to their detonation rates, densities, and water resistance. There are also numerous products within each classification depending on their utilization or on their permissibility in various types of underground mining operations.

Jan 1, 1985

By Y Wada, Y Ogata, T Nishida

"Shaped charge is used for blast demolition of steel construction in general. It is important tocontrol movement of cutting part with shaped charge for the blast demolition of steel construction.Movement of cutting part was studied in the small scale experiment with steel bar. A numericalsimulation using the Discontinuous Deformation Analysis (DDA) was carried out. The DDAmethod was applied to the full scale blast demolition of steel construction. Results of thesenumerical simulation was compared with the blasting demolition work of steel tower."

Jan 1, 1999

By R W. Bellenie, P N. Blakey

The phenomena of post detonation gases in muckpiles is reasonably well known. It causes the 'rumbling' noises occasionally heard after a blast in open pits or quarries and is thought to occur due to initiation of carbon monoxide, hydrogen, etc. by 'hot' spots within the muckpile. The problem usually occurs with highly aluminized products, but can occur with any oxygen deficient product. This phenomenon was never a problem underground due to restriction on access to blast areas, ventilation criteria, etc. until the advent of large diameter blastholes and particularly their use for specialized applications such as drilling for blasting down 'hang-ups' in ore passes.

Jan 1, 1980

By D K. Joyce, B Mohanty

In a previous paper, it was shown that a lack of clear understanding of the role of initiation mode on detonation characteristics often leads to under-utilization of the explosive system in blasting. This is of particular significance since the very large number of explosive initiation practices currently in use implicitly assumes that the blasting performance of an explosive is largely independent of the exact mode of initiation. This paper deals specifically with bulk-loaded and pneumatically-loaded ANFO under various initiation modes in small diameters. These include initiation by booster and detonating cords of various strengths, and combination of cords and boosters. The nature of energy release and energy partitioning between shock and gas energy have been studied in the underwater test as a function of charge diameter. The paper describes the relative merits of various initiation modes for specific charge geometries and confinement, under end- and side-initiated conditions. Guidelines have also been formulated for use in the field to match initiation practice with blasting requirements.

Jan 1, 1994

By R. F. Favreau, Patrice Favreau

"Ever since we have started to assist those responsible for blasting with blast simulation studies, we havebecome aware of an interesting aspect, namely that in 90 % of cases we are asked ‘‘Can you seek ablasting method which gives better fragmentation than the method which we use now’’. But after a visit to the site, and the evaluation of the fragmentation obtained with their present blasting method, it very often becomes evident that it is the ease of mucking and not the fragmentation which requires improvement. Hence we then proceed to do a simulation study the results of which are improved mucking rather then more fragmentation, and those responsible for the blasting always become very satisfied."

Jan 1, 2017

By Ruilin Yang

The vector sum peak particle velocity (PPV) of blast vibrations describes the blast vibration intensity more completely than the PPV of a single component waveform. It is more logical to use a vector sum PPV as a vibration limit than using a single component PPV. In 1980 the USBM recommended the frequency related peak particle velocity criterion. So far this method has been only applied to single component waveforms, but not to the vector sum PPV since there is no method available to associate a frequency to the vector sum PPV. The present paper describes a method to define a principal frequency associated with vector sum PPV. The method is based on the weighted average of the principal (zero-crossing) frequencies of the three tri-axial components at the time of the PPV.

Jan 1, 2015

By H Y. Fang, H Sutherland, R M. Koerner

Due to the increased number of complaints by property owners to blasting related industries an apparent need for a clearer understanding of blasting-related damage is needed. We feel that direct structural crack monitoring during such blasts is the appropriate measurement technique. Instrumentation and interpretation of results for taking such measurements are described in this paper. Typical results from blasting and other environmental effects are also described which can eventually be related to Fracture Mechanics principles in the hope of clarifying such disputes in an equitable manner.

Jan 1, 1976

By Roger L. McCarthy, Ali Reza

The use of an ammonium nitrate-fuel oil (ANFO) explosive in the Oklahoma City Federal Building bombing has led to a renewed interest in using additives during the manufacturing process of ammonium nitrate to render it non-detonable. Suggested additives include calcium carbonate, which is already used in some European countries, and mono-ammonium phosphate (MAP) or di-ammonium phosphate (DAP), which are the primary desensitizing agents claimed in US patent 3,366,468, Method for desensitizing fertilizer grade ammonium nitrate and the product obtained, issued Jan. 30, 1968 (Porter, 1965).

Jan 1, 1999

By John R. Jr Tripi, Paul N. Worsey

Split round blasting is commonly practiced in underground uranium mining in the Big Indian ore belt located in Southeast Utah. The technique is used to prevent ore dilution by separately blasting the ore from the face.

Jan 1, 1985

By Thomas E. Lobb, Harry C. Verakis

Blasting is a primary means of extracting minerals and ores at surface mining operations. The domestic consumption of explosives and blasting agents during the year 2001 was about 5.25 billion pounds. Flyrock is always a major concern for the blaster. Flyrock from surface blasting operations has caused serious injury and death to employees and other persons. Injuries due to flyrock and the lack of blast area security accounted for over two-thirds of all blasting-related injuries in surface coal, metal, and nonmetal mines during the period 1978-2002. Selected accidents due to flyrock and lack of blast area security in surface mining are presented in this paper. Incidents related to construction blasting are also described. Techniques to mitigate blasting accidents are discussed. These include proper blast design, driller-blaster communication, inspection prior to loading and firing the blast, removing employees from the blast area, controlling access to the blast area, and using a blasting shelter. An experienced driller could detect potential problem areas such as voids, mud seams, incompetent rocks, and other irregularities by observing the progress of drilling. The drill log should include the details of any unusual or exceptional circumstances noticed during drilling. A blaster may need to alter the loading configuration to alleviate potential problems. Basic blast design is sometimes taken for granted and assumed to be proper for the conditions encountered, but one size does not fit all. It is known from the physics of blasting that the explosive energy takes the path of least resistance. The path of least resistance could generate flyrock, depending on the blast site conditions. A combination of ‘borehole tracking’ and ‘laser profiling’ can assist in improving the design of a blast. The blaster can use these tools to adjust borehole loading to match site conditions.

Jan 1, 2004

By Tom Short, Bill Beam

Some of the weapons testing shafts at Mercury, Nevada require depths of 1000ft and diameters of 10 feet. The top 40 feet to 65 feet is drilled, blasted and excavated by Large caisson type augers in order to provide vertical working room for the placement of large, oil field type, drilling rigs and the required drill collar.

Jan 1, 1991

By Calvin Konya, Janos Foldesi

A bridge over a main line railroad system was scheduled for demolition. The bridge was made of reinforced concrete and spanned three mainline railroad tracks which could not be shut down due to blasting or demolition. To further complicate matters, the mainline tracks had high tension power lines running above the tracks, but below the bridge. These high tension wires provided the electricity for electrically powered trains. The tracks could not be damaged or disrupted, nor could the power line be broken.

Jan 1, 1992

By J R. Brinkmann, S G. Giltner

Nearly all of the South African gold mining industry still uses fuse and igniter-cord initiation systems. Over the past 30 years numerous attempts at developing new initiation systems have not yielded a viable alternative. New initiation systems for narrow stopes are currently being developed by various concerns and the likelihood of these efforts producing feasible alternatives is greatly improved due to the recent advances in electronics technology. The greatest potential benefit of alternative initiation systems is increased production rates through improvements in accuracy and reliability of firing over that of fuse/igniter-cord. Another important feature is the capability of millisecond delay firing as this can lead to reduced stope cleaning times by way of enhanced rock throw and improved fragmentation characteristics.

Jan 1, 1989

By Mike Koehler

An underground mine that produces aggregate limestone was in operation for approximately eight years when geological changes resulted in dangerous rock falls. The roof in the mine was not bolted; therefore, the drilling and blasting program was called upon to maintain roof integrity. Drilling and blasting were analyzed and modifications were adopted to stabilize the roof. Initial changes were made in the drilling equipment, drill pattern, explosive type, and timing. Any amendments made, after the initial phase, were made individually so it would be easy to discern which changes worked.

Jan 1, 2002