Search Documents

By Alfred Osborne

Progressive cavity type pumps are widely used by commercial explosive manufacturers for pumping water gel, emulsion and emulsion / ANFO blend explosives. Tests by explosives companies and investigations into incidents have shown that this type of pump can develop dangerously high temperatures when operated deadheaded or dry. [i.e. with no flow of product through the pump.] In some tests and incidents, explosion or detonation of the explosive (or residual explosive) in the pump has resulted.

Jan 1, 2002

By Edward J. Walter

An ancillary effect to every blasting operation is the generation of vibration Extensive research has been performed for the purpose of understanding, controlling, and predicting this vibration An examination of these studies clearly shows a variability in the resulting vibration effects It seems logical to expect that identical blasting procedures should produce identical vibration levels, but this is rarely the case. There is a distinct pattern of variation.

Jan 1, 1980

By Karl Kure, Anders M. Heltzen

Mixtures of prilled ANFO and 0,5 - 3 mm polystyrene balls are interesting substitutes to the tube charges or other types of reduced explosives or detonation fuses. Experiments have shown detonation ability even of a mixture of 95% bolt polystyrene balls and 5% ANFO. The gas and shock energy in the mixtures decrease proportional with the content of polystyrene. The detonation velocity shows higher values than expected for mixtures with more than 50% (vol.) ANFO.

Jan 1, 1980

By Janos Foldesi, Calvin J. Konya

The determination of the number of primers necessary to efficiently initiate an explosive column charge is essential to good blasting. If the number of primer is insufficient, the total energy stored in the main charge will not be released. On the other hand, the use of too many primers will be counterproductive and raise the blasting cost. Tests were conducted by the authors to determine the correct priming procedure for a basalt quarry. This paper describes the results of those tests.

Jan 1, 1976

By Winston Wilches B., Scott Scovira

This paper discusses recent changes to the emulsion blend blasting agent used at the Drummond Pribbenow Mine in Colombia, one of the world’s largest open pit coal mines, and the resulting improvements in rock breakage and excavator productivity. Based on field evaluations, the use of High Density Ammonium Nitrate (HDAN) can be effectively implemented in an emulsion blend blasting agent, yielding excellent results in terms of energy release, shelf life and velocity of detonation (VOD). Field evaluations showed that formulations using HDAN exceed the performance of the actual 50%/50% emulsion/ANFO blend using Porous Prill Ammonium Nitrate (PPAN). PPAN is conventionally used for emulsion blend manufacturing, with physical characteristics to facilitate sensitivity during the detonation process.

Jan 1, 2014

By G J. Kulbieda

The Empire Mine initiated production in 1963. Since then the unit operations of drilling and blasting have evolved continually in order to meet the increased mining requirements demanded by plant expansions in 1968, 1973 and 1980. Additionally, advance mine planning has become an integral part of proper pit development and is necessary to insure uniform blending of the distinct ore horizons contained within the mine area. Blasting practices have been modified to facilitate the autogenous grinding system utilized at Empire and pioneered in the Iron Ore Industry. Technical innovations in the explosives industry, as well as, progress regarding on site blast engineering methods have substantially increased the use of ammonium nitrate explosives and helped to establish efficient charging procedures. In addition, the recent introduction and use of ammonium nitrate fueled with nitropropane and methanol indicates that it is a viable substitute for aluminized ANFO.

Jan 1, 1981

By Claude Cunningham, Szendrei

The partitioning of blasting energy into “Shock” and “Heave” components is a popular concept for attempting to match explosives to particular ground conditions and blasting results. The issue is complex, as it affects both the detonation process and the immediate response of the rock skin. However, the fundamental process of energy transfer from the explosive to the rock through the blasthole wall is not well defined. Clues to the “Shock” phase of blasthole expansion are given by cratering behaviour of materials subject to high velocity penetrators. The final cavity volume defines both the energy used to achieve this and the resistance of the confining material. Attention is being given to the link between penetration of a solid target and expansion of a readymade hole, both producing the same outcome. The benefit of this work is that it leads to clearer understanding of how explosives will impact upon the blasting results and helps to explain the energy consumption in blasting.

Jan 1, 2004

By W. Jiao, Y. Yongqi, R. Shan

Soft rock mines are distributed through out P.R.C. And drilling and blasting is still the main method of driving a tunnel in these mines. Traditional smooth blasting has been widely and deeply studied and put into practice in P.C.R since 1970s. But the cartridge and blast hole are both columns, the stress field in the rock around blast hole at the beginning is symmetry around hole axis, and the original cracks in the rock can be activated randomly. So serious overbreak and underbreak at the boundary of an excavation occur often, especially when the excavation is in soft rockmass, and the rates of half-hole marks are generally about 50% in medium rock, and 20-30% in soft rock in Chinese coal mines. For the sake of overcoming the situation, we have been studying directed crack blasting since ten years, and have got some obvious achievements in this respect. Slotted cartridge control blasting in soft rock is studied in this paper. Through model experiments, reasonable decouple coefficient range and slot width are gotten, and unsymmetrical dynamic strain field is analyzed. Through underground test in soft rock with a strength lower than 1OMpa in Dayan Mining Bureau, The results of which the rates of half-hole marks and the nonsmooth grades of the cut contours are 83.3% and 1OOmm respectively have been achieved.

Jan 1, 2000

By Jacques Monette, P K. O'Connell, Keith Boyle

The mine contracting industry in Canada is no different from any other industry in its quest for productivity improvements. Dynatec Mining Ltd. has focused on drilling and blasting of rounds as an area for improvement. This paper describes the development of blasting long rounds in shaft sinking as well as a description of the lateral excavation system as applied at Aur Resources Inc., Louvicourt Project.

Jan 1, 1994

By Norman S. Smith, Richard L. Ash

Relationships between the three design factors of borehole burden, spacing, and length that control rock breakage were examined by means of reduced-scale bench blasts in dolomite. A set of three indices were developed for analyzing the differences between fragment-sizing distributions obtained from various design combinations. It was found that the factors were interdependent and the indices were directly related to the common stiffness relationship for solid structures. The burden-spacing-length combinations that produced the best and poorest overall breakage, maximum and minimum overbreak, and least and most toe were determined.

Jan 1, 1977

By J R. "Dick" Daniel

Over the past several years, the Hercules Technical Service Group for the Explosives Department has produced a series of programs for the TI59 programmable calculator dealing with explosive application problems. These programs have been made available to both our internal staff and to the Hercules explosives distributor organization. Several of these programs have found good acceptance and wide usage.

Jan 1, 1984

By R Deshaise, B Mbhanty

The importance of controlling density of commercial explosives, and the various means to achieve it are described. m e field conditions responsible for density changes during blasting and their effect on blast results are examined. Understanding of the behaviour of density control ingredients such as gas bubbles, glass and plastic microballoons under pressure, is considered essential to predicting explosives performance. Both static and dynamic pressure effects have been studied for typical donor-receptor cartridge configurations. The amplitude and temporal characteristics of dynamic pressures inside receptor explosives have been studied by means of the underwater test, and guidelines developed to limit density changes due to external pressures.

Jan 1, 1989

By P D. Katsabanis

The phenomenon of sympathetic detonations in blastholes is investigated by comparing experimental observations and numerical modelling results. Numerical modelling using the TDL computer code and Forest Fire decomposition rates for commercial explosives has shown the importance of blasthole diameter, impedance of stemming material and host rock. Comparison with experimental observations has also shown that sympathetic detonations cannot always be treated as shock to detonation transitions (SDT). Examination of previous results which have been obtained from calibrated low amplitude shock experiments reveal that there is an ignition threshold prior to the detonation threshold. The difference between the two thresholds is more pronounced in the case of air bubble sensitized products. The ignition threshold can be very important under the confinement provided by the blasthole and the conditions of application. It also correlates well with the pressures expected at the gap distances of interest in the practical application. It is suggested that critical energies are used as the criterion for cross initiation in blastholes. Practical suggestions based on the numerical calculations and experiments based on these calculations are also given and discussed.

Jan 1, 1992

By P. R. Mohanty, Kaushik Dey

Blast-induced tunnel overbreak prediction in the past has been based on peak particle velocity measured far from the blast site with necessary extrapolation. This has often resulted in suggesting higher damage threshold levels of Acceleration/PPV for overbreak prediction (Bogdanhoff, 1995, Holmberg and Persson, 1997, Murthy and Dey, 2002). These, site-specific far-field blast vibration studies, have also revealed that predicted PPV levels for overbreak could lie in the range of 700-5000 mm/s, an extremely wide range to generalize. Experimental blasts were conducted, in an underground metal mine located in eastern India, with an objective to study the level of acceleration /peak particle velocity generated in tunnel blasting. Accelerometers and tri-axial geophones with measuring ranges upto 500 g, 254 mm/s respectively, were mounted on the tunnel floor close to the blast face, with sensor distances varying from 15.25m to 36.10m. Due to straight faces the measuring distance could not be reduced further anticipating, in particular, cable damage. The equipment used was of M/s Instantel Inc., Canada. The blast pattern used was burn cut with large dia relief holes providing the required free face. The blast hole depth was 1.8m. Tunnel overbreak was measured using a telescopic offset rod fabricated at Indian School of Mines, Dhanbad, India.

Jan 1, 2004

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 Ettore Contestabile, Cameron Thomas

Implosive-type electrical/mechanical connectors such as XECONEX have been used extensively for joining electrical transmission lines. This implosive action of explosives has also been applied to other forms of high energy metal working with excellent results. However, as with many other products, the inherent blast energy of these units has caused some environmental concerns especially when used in proximity to inhabited areas.

Jan 1, 1995

By Ivan Kovac, Pero Marjanovic, Branko Bozic

"The paper deals with results of geophysical survey of the rock masses, and the blasting parameterswhich have effect on the fragmentation in quarries . A relationship between the burden, which is the distance between the charged borehole and the free rock surface, and the velocity of longitudinal waves in the rock mass is established based on measured values for different quarries. It is shown that the drilling geometry can also be detemrined from this relationship."

Jan 1, 1999

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

By Richard J. Mainiero, T S. Bajpayee

The U.S. Bureau of Mines (Bureau) has conducted research to evaluate the firing accuracy of electric delay detonators used in surface blasting operations. Over four billion pounds of explosives and blasting agents are used every year in surface blasting in coal, metal and non-metal mines. In a typical large-scale surface blast, several thousand pounds of explosives are fired in a timed sequence using delay detonators. The delayed firing of explosive charges allows time for the fragmented rock to move out before the next charge is fired.

Jan 1, 1990

By Michael S. Wieland

The stress waves generated during delay blasting in underground or surface mines not only fracture the surrounding coal, rock, or other strata, but also impact delayed charges remaining in neighboring boreholes. This crossing wave interaction is a ubiquitous fundamental damage mechanism, ultimately responsible for numerous occurrences of misfires and flyrock. The hazards and waste from wave-induced malfunctions are Just the recognized tip of the iceberg. Undetected marginal performance of damaged delay detonators and desensitized charges poses a tremendous unresolved problem, resulting in the reduction of mining profits and the certain retention of unwanted risks.

Jan 1, 1988