Detonation Velocity Of Explosives Research Articles

Effects of oxidizer on the secondary reaction of aluminum and metal acceleration for CL-20-based aluminized explosive

Abstract The addition of oxidizing agents in the explosives could enhance the burning rate and the reaction degree of aluminum powder due to the increase of oxidizing gas content in the detonation products. Therefore, it affects the metal acceleration ability of the explosive. The current study is concerned with investigating the metal acceleration ability of the CL-20-based aluminized explosive containing oxidizer affecting metal shells through standard cylinder tests. The diameter of the cylinder is 50 mm. An all-fiber displacement interferometer system with a photon Doppler velocimeter took into account the continuous measuring of the cylinder wall velocity over time. The detonation velocity was calculated by the velocity jump time interval of the cylinder wall. BKW equation was applied to calculate the detonation pressure. The effects of oxidizer on the ignition time and the reaction degree of aluminum powder were analyzed by replacing aluminum powder with lithium fluoride for comparison. According to the cylinder wall velocity energy source, empirical formula about explosive composition and the cylinder wall kinetic energy was fitted. The results show that CL-20-based aluminized explosive detonation velocity and aluminum content is linearly correlated, and oxidizer-containing explosives detonation velocity can be equivalent to oxidizer-free explosives within a certain margin of error. With the addition of oxidizer, detonation pressure, and the base explosive content no longer show the same increasing and decreasing relationship. When the aluminum content is 5% and 30%, the ignition time of aluminum powder is 4.81μs and 1.66μs earlier respectively. When the aluminum content is 5%, the reaction degree of aluminum powder reaches 1. The aluminum powder reaction rate for oxidizer-containing explosives and oxidizer-free explosives is mutually fast and slow. When the aluminum content is 30%, aluminum powder reaction degree and aluminum powder reaction rate for oxidizer-containing explosives are higher than that of oxidizer-free explosives throughout. Based on the fitted relationship equation, it is predicted that the maximum value of kinetic energy of the cylinder wall is obtained at 10% aluminum powder content with 10% oxidizer.

Effect of modified coated aluminum powder on the explosive properties of emulsion explosive

Abstract In order to investigate the effect of aluminum powder content on the detonation properties of emulsion explosives and to reduce the emulsion of aluminum powder on the emulsion explosives to improve their service life, the paraffin-coated spherical micron aluminum powder is used to prepare the proportion of 0%, 5%, 7%, 9%, 11%, 15%, and 20% of the aluminum-containing emulsion explosives. Using the chronometer method to determine the detonation velocity, the lead column compression method to assess its brisance, and conducting underwater explosion tests to calculate parameters such as shock wave energy, bubble energy, and total energy of the aluminum-containing emulsion explosives. Additionally, high and low-temperature cyclic accelerated aging tests are performed to study the effect of aluminum powder on the service life of the emulsion explosives. The results show that aluminum powder mass fraction of 5%, containing aluminum emulsion explosive detonation velocity, is the largest, 5459m·s−1, with the increase of aluminum powder content, containing aluminum emulsion explosives detonation velocity of the overall trend of reducing. Briance first increased and then decreased, reaching a maximum value of 24.06mm in 15%. The total energy of the underwater explosion increases with the increase in aluminum powder content. In the aluminum powder mass fraction of 20% to reach the maximum, the shock wave energy increased by 26.7%, the bubble energy increased by 65.4%, and the total energy increased by 65.4%. The service life of paraffin-coated aluminum emulsion explosives is better than that of emulsion explosives containing ordinary aluminum powder service life.

Effect of explosive detonation velocity on the degree of rock pre-fracturing during blasting

At many quarries for the extraction of building stone there is a problem of increased output of fines after all stages of crushing and grinding, which leads to a decrease in the economic performance of mining enterprises. The fine fraction is formed by the crushing / grinding of prefractured rock mass. Reducing the intensity and size of the prefracture zones will lead to a solution to the problem at hand. To determine the effect of explosive detonation properties on the degree of structural weakening of a rock mass, studies were conducted to measure the detonation velocity, stresses generated by a blast in the rock mass, as well as laboratory studies of microfracturing by X-ray computer microtomography. The size of the prefracture zones increases from 33 to 77 charge radii with increasing the detonation velocity from 2 to 5.2 km/s. The dependence of the number of microdefects (microfractures) generated by a blast on the velocity of explosive detonation takes the formof an exponent for the near zone and is linear for the distances far from the blast. According to the data of the experiments conducted at short distances (10R), the density of induced microfracturing N is within ≈5 thousand pcs/cm3, and with increasing the detonation velocity it increases to ≈13.8 thousand pcs/cm3. At medium (40R) and long (70R) distances, N increases from ≈750 to ≈2,400 pcs/cm3 and from 0 to ≈200 pcs/cm3, respectively. Using explosives with a reduced detonation velocity allows reducing the “surplus” impact on a rock mass and thus reducing the intensity of prefracture in the zone of controlled crushing during a blast. The study allowed obtaining quantitative parameters of the intensity and size of the prefracture zones, which compose the supplement to findings of historical studies on qualitative determination of prefracture.

QSPR study to predict the detonation velocity of explosives with emphasis on studying the electronic spectra of RDX

The study devoted to calculate and interpret the electronic spectra of the RDX molecule. The six isomers of the RDX molecule were geometry optimized with the MP2/cc-pVTZ level of theory. The twist isomer was shown to be the most stable isomer. The electronic spectra of the six isomers were calculated with acetonitrile as a solvent. The electronic spectra were calculated using the PBE0/def2-tzvppd level of theory in acetonitrile as a solvent. The combined PBE0/def2-tzvppd// MP2/cc-pVTZ methods succeeded in reproduce fairly the experimentally measured main band at 236 nm. The calculated wavelength was 237 nm and the band was shown as mainly originated from the HOMO to LUMO transition with a transition probability of 0.49688 which is 49.4% of the overall transitions responsible for this band. The calculated spectrum of the most stable isomer (twist) was most relevant to the experimental spectrum. In order to predict the detonation velocity of explosives the Quantity Structural-Property Relationship calculations were done and a statistical empirical equation was built based on the measured detonation velocity of well-known explosives and several structural and electronic descriptors.

Влияние эмульсионных взрывчатых веществ на скорость детонации скважинного заряда

The input control of explosive materials and the measurement of the detonation rate of the charge are important in the production of explosive work. The detonation rate of the explosive charge, as one of its most important characteristics affecting the quality of the explosion, depends on many factors, the main of which are: the quality of preparation of explosives and their components. Incorrectly selected parameters of drilling and blasting operations and poor quality of preparation of explosives lead to a decrease in the detonation rate up to detonation failures. In turn, detonation failures lead to an increase in material costs and an increase in the risk of negative events related to safety when handling explosive materials. The correct approach to preliminary quality control with the use of appropriate measurements will improve the efficiency and safety of preparing the rock mass for excavation by drilling and blasting. The article presents a technique for measuring the detonation velocity of a borehole charge with the corresponding results and conclusions, allowing timely measures to be taken to maintain the detonation velocity of explosives at the required level.

Explosion wave and crack field of an eccentric decoupled charge.

To investigate the characteristics of the explosion damage from an eccentric decoupled charge, the rock-breaking mechanism of an eccentric decoupled charge is revealed from the perspectives of the explosion wave field and crack field through theoretical and experimental analyses. The ratio of the maximum to minimum pressure on an eccentric decoupled hole wall increases exponentially with an increase in the decoupling coefficient, but it does not change with a change in the explosive density or explosive detonation velocity. The explosive energy on the eccentric charge side has a certain accumulation effect, the velocity of the reflected shock wave at the blasthole wall is greater than that of the incident shock wave, and the incident velocity of the explosion wave on the eccentric side is greater than that on the non-eccentric side. The expansion range of the explosion gas is significantly better than that on the non-eccentric side, indicating that the eccentric decoupled charge can strengthen the action of the explosion gas product on the eccentric side. In addition, the overpressure of the explosion wave on the eccentric side is greater than that on the non-eccentric side. The fractal dimension and damage degree of the explosion crack on the eccentric side are larger than those on the non-eccentric side. The explosion cracks can be divided into intensive, transition, and sparse areas, and the fractal dimension and damage degree decrease successively in the three areas. The explosion cracks formed on the non-eccentric side outside the range of three times the blasthole diameter concentrate in the sparse area, and the destructive effect of the explosion on the non-eccentric side medium is effectively reduced.

Rational crushing of mineral raw materials by well charges as a factor of environmental safety of blasting works in quarries

Purpose. Improving the environmental safety of blasting operations in quarries for the extraction of non-metallic and construction materials based on their rational explosive crushing, aimed at reducing the effect of overgrinding, accompanied by the formation of fine fractions of materials and significant dust emissions. The research methodology provided a theoretical analysis of the destruction processes of a rock massif by well charges of explosives on the basis of calculations of shock adiabats of an explosive wave in rocks at different speeds of detonation of explosives. Experimental verification of the identified patterns was performed by assessing the quality of blasting by the particle size distribution of the rock in the collapse. Research results. The scientific and practical task of ensuring rational explosive crushing of materials in quarries with the use of elongated borehole charges has been solved. Mechanisms for the destruction of rock massifs and the peculiarities of the distribution of destruction zones by dispersed composition have been established, which contributes to the reduction of dust emissions into the atmosphere to an acceptable level of environmental safety of blasting operations in quarries. Comparative estimates of the shock load during the explosion of the explosive charge for the main rocks at different levels of the rate of detonation of charges are given. The dependence of the volume of overgrinding rock in the zone of its adjacency to the charge on the detonation velocity of explosives has been established. An experimental verification of the identified patterns in the current quarry by assessing the quality of blasting by the particle size distribution of rock mass in its collapse after experimental explosions with different parameters is done. Scientific novelty. The multiphase process of rock destruction by explosion was investigated by the calculated determination of the parameters of the shock adiabats of the blast wave in different rocks and at different detonation velocities of explosives. It is shown that during the destruction of a rock mass by the explosion of an elongated borehole charge of explosives, several specific zones of destruction are formed, the characteristics of which differ in particle size distribution. The area of controlled crushing is highlighted, where the intensity of rock destruction can be changed by adjusting the parameters of the explosive load and the area of little or almost unregulated crushing. The possibility of managing the process of dust formation and, accordingly, the level of environmental safety of blasting works in quarries for the extraction of non-metallic and construction materials is substantiated. Practical meaning. The identified patterns and provisions to reduce the effect of mineral overgrinding were used in the development of measures to improve the environmental safety of blasting in the quarry, which, in particular, provided an increase in well spacing in the range up to 3.0-3.4 m and reduce specific energy consumption from 1.27 g/cm3 to 0.97 g/cm3.

Control of density and velocity of emulsion explosives detonation for ore breaking

Purpose.Development of a new procedure for calculating the density of emulsion explosives (EE), that will allow determining the detonation velocity along the charging length, depending on the inclination of boreholes during ore breaking. Methodology.A calculation method for the redistribution of EE density and mass in boreholes at different angles of inclination has been developed by using the well-known laws of hydrostatics. Measurement of the detonation velocity of the EE Ukrainit-PP-2B was conducted by using the method of polygon experimental tests. The numerical simulation of changes in the detonation velocity of explosives in boreholes was conducted by using the proposed method and established regularities. Findings.Methods of calculation of EE density changing along the charging column length under the action of hydrostatic pressure at different angles of inclination of both ascending and descending boreholes have been developed. Based on experimental data, regularities of detonation rate changing from density and charge diameter for EE Ukrainit-PP-2B, varying according to exponential law have been established. The rational initial density of EE Ukrainit-PP-2B has been established for ores breaking by boreholes, which is equal to 8001000 kg/m3, at which the detonation rate along the length of the charge column at different angles of inclination of the boreholes is maintained. The obtained results will allow controlling density and detonation velocity during ore breaking. Originality.The density of EE increases in the formed charging column under the action of hydrostatic pressure: in ascending boreholes from the face, while in descending boreholes from the brow. Practical value.Application of the calculation results of EE density at different inclination angles of boreholes makes it possible to determine in the charge column sections with its critical values more than 1410 kg/m3, at which a sharp attenuation of the detonation rate begins. Consideration of this phenomenon makes it possible to prevent the occurrence of failures at the explosion of charges in boreholes during ore breaking.

A Simple Approach to Assess the Performance of Non‐ideal Aluminum/Ammonium Perchlorate Composite Explosives as Compared to the Best Available Methods

Composite explosives containing aluminum/ammonium perchlorate (Al/AP) are widely used for blasting cut of old warship, blasting droll and decoupled charge of blast underwater. The available complex computer codes and empirical methods cannot usually provide a reliable estimation of detonation velocities of explosives containing Al/AP. This work introduces a reliable method for the desk calculation of detonation velocity. The percent of the reacted Al with detonation products and decomposition of AP, as well as composition of the detonation products, are specified according to the distribution of oxygen atoms between Al, C(s), CO(g) and H2(g). The values of the mean absolute percentage error (MAPE) of the new model are lower than one of the best available methods for CHNO explosives (260 experimental data) and CHNOFCl explosives (50 measured data). For composite explosives, CHNOFClAl and CHNOFClAlAP, the MAPE value of the new model is 3.50, corresponding to 55 experimental data, which is much smaller than the MAPE values of the BKW computer code (8.37) and the comparative empirical model (14.20).

On Nanosecond Thermophysics (Review)

A review of highly nonequilibrium states generated in solids and liquids by a short shock-wave action is presented. States with large deviator stress components, large negative pressures, overheating of the solid phase, supercooling of the liquid phase, and issues of viscosity of liquids (including metal melts) and solids at strain rates up to 108 s–1 and high pressures are considered. The dynamic tensile strength (cavitational strength) of metal melts, fast polymorphic transformations, and a new rule for selecting the detonation velocity of explosives are discussed.

Dependence of Detonation Velocity of Explosives on Effective Atomic Number and Effective Electron Density of the Explosives

Detonation velocity is one of the most important characteristics of explosives. For solid hydro carbon-based explosives it is generally greater than 4000 m/s. Detonation velocity depends to some extent upon the particle size of the explosives, increased charge diameter and increased confinement of the explosive. There is no report indicating the dependence of detonation velocity on the effective atomic number and effective electron density of the explosive. In the present work, we have arbitrarily chosen eight explosives. Four of these have detonation velocity between 9400 and 10100 m/s, and the other four has detonation velocity between 4500 and 5300 m/s. Direct method was used to calculate effective atomic number and effective electron densities various explosives. On calculating effective atomic number and effective electron density, it was found that detonation velocity of explosives does depend upon these two parameters. For explosives with high detonation velocity, effective atomic number is high and effective electron density is low while for low detonation velocity explosives it is reverse. It was also found that the variation of effective atomic number and effective electron density as a function of gamma ray energy can be explained on the basis of three different gamma ray inter action mechanism of gamma rays with matter.

Dependence of the Detonation Nanodiamond Yield on the Detonation Process Parameters

To determine the dependence of the yield of detonation nanodiamonds (DNDs) on the power of explosives used, a new concept is introduced—the specific power of explosives (to which the detonation velocity of explosives and the pressure of gases in the Chapman-Jouguet plane are related), which is given by the ratio of the heat of explosion to the unit mass and time. The DNDs yield has been found to depend on the detonation velocity and pressure in the Chapman-Jouguet plane. The optimum yield of DNDs (> 5 wt %) is achieved when the specific power of explosives is 30000 to 60000 kJ/(kg·µs), the detonation velocity is 7250 to 8000 m/s, and the pressure in the Chapman-Jouguet plane is 21 to 28 GPa.

Analysis of the goodness of empirical approaches in predicting explosive detonation parameters

Goodness of empirical models for predicting explosive detonation velocity and pressure was analysed using 3 databases consisting of experimental velocity and pressure measurements for different explosives. The first database was used to estimate experimental errors for detonation velocity and pressure measurements. The second database was used to compare residuals obtained by the experimental models and by various thermochemical codes. Finally, the third database, consisting of some 600 data on 130 explosive substances, was used to estimate residual bias and dispersion resulting from the application of the experimental models. Also analysed was model coherence with the ideal detonation theory. Our main conclusion is that all the models introduce bias in their predictions depending on the density and oxygen balance values of the explosive. Of those analysed, the Xiong model was notable for its good results, with residual dispersion comparable to that obtained from application of the best thermochemical codes. Our results would indicate that the Xiong model is the only model that may be compatible with the ideal detonation theory. The pressure equation derived from the ideal detonation theory and calibrated with experimental data had excellent predictive capacity.

The Impact of Time on the Detonation Capacity of Bulk Emulsion Explosives based on Emulinit 8L

AbstractOne of the elements of enhanced safety of mechanically loaded emulsion explosives is the loss of its explosive properties after a certain period of time, without reference to the particular research. The manufacturer described this time for approximately 48 hours from the time of its charging to the blasting holes with a gas sensitized product. Under regular conditions of mining works, this time is absolutely sufficient for safe mining operations. In practice, some unforeseeable situations may occur that the charged explosive is not fired within the prescribed period of time. The aim of the study was to verify the knowledge regarding the behavior of mechanically loaded emulsion explosives used in Polish underground copper mines by tracking the changes of detonation velocity over time. The subject of research was Emulinit 8L emulsion explosive manufactured by NITROERG from Bieruń, Poland. The measurements were provided using a MicroTrap™ VOD/Data Recorder, which allows for continuous measurement of the detonation velocity of explosives.

Cover Picture: A New Method for Predicting the Detonation Velocity of Explosives with Micrometer Aluminum Powders (Prop., Explos., Pyrotech. 4/2018)

Cover Picture: A New Method for Predicting the Detonation Velocity of Explosives with Micrometer Aluminum Powders (Prop., Explos., Pyrotech. 4/2018)

A New Method for Predicting the Detonation Velocity of Explosives with Micrometer Aluminum Powders

AbstractIn the present study we carried out a thermodynamic analysis for explosives with micrometer aluminum (Al) powders, and found that the acceleration of Al powders and heat exchange between Al powders and the detonation products may have a significant influence on the detonation velocity. Relying on velocity disequilibrium between the two phases at the C−J plane and heat absorption of inert Al powders in the detonation zone, this paper has introduced a new method to study the detonation velocity of explosives with micrometer Al additives. The method is a closed system of algebraic equations and the detonation velocity can be solved efficiently by numerical codes. The detonation velocities predicted by the new method are in excellent agreement with experimental data of RDX‐, HMX‐, NM‐ and TNT‐based aluminized explosives, and the heat exchange has been proved significant on the detonation velocity, while the acceleration of Al powders is of little effect.

Estimation of Influence of Explosive Characteristics of Emulsion Explosives on Shotpile Width

The article deals with the question of the effect of explosive characteristics of emulsion explosives on the shotpile width. Currently, there are two main points of view to select an efficient type of explosive, which contributes to the qualitative destruction (fragmentation) of coarse clastic rocks. The first is based on the assumption that the detonation velocity of explosives must correspond to the break-down point of the rock (dynamic compression). Another point of view is that the detonation pressure of explosives determines only the head part of the pulse, on which the rock fragmentation is dependent only near the charge, in the contact zone around the borehole. The fragmentation of the entire rock volume within a given borehole array depends on the total magnitude of the explosion pulse, determined not by the detonation velocity, but by the total energy reserve of the explosive charge. Experimental explosions with some of the most common industrial explosives have been carried out in the current conditions of blasting of borehole charges by various types of industrial explosives from the point of view to select the most important parameter, which determines its influence on the shotpile width The investigations have been carried out according to the data obtained to establish that the energy properties of explosives (heat of explosive transformation and density of explosives) determine the decisive influence on the shotpile width, and the operability, the volume of the released gases, the detonation velocity for the change in the shotpile width have very little effect and may not be taken into account in calculations for the prediction of the shotpile.

Effect of the Detonation Velocity of Explosives on Seismic Radiation

We studied seismic body-wave generation from four fully contained explo- sions of approximately the same yields (68 kg of TNTequivalent, where TNT stands for trinitrotoluene) conducted in homogeneous granite in Barre, Vermont. The explosions were detonated using three types of explosives with different velocities of detonation: black powder (BP), ammonium nitrate fuel oil/emulsion (ANFO), and composition B (COMP B). The main objective of the experiment was to study differences in seismic- wave generation among different types of explosives and to determine the mechanism responsible for these differences. The explosives with slow burn rate (BP) produced lower P-wave amplitude and corner frequency, which resulted in lower seismic efficiency (0.21%) in comparison with high burn rate explosives (1.3% for ANFO and 1.9% for COMP B). The seismic efficiency estimates for ANFO and COMP B agree with previous estimates for nuclear explosions. The body-wave radiation pattern is consistent with an isotropic explosion with an added azimuthal component caused by vertical tensile fractures oriented along pre-existing microfracturing in the granite, although the complexities in the P- and S-wave radiation patterns suggest that more than one fracture orientation could be responsible for their generation. Analysis of the S/P amplitude ratios suggests that a significant fraction of the shear-wave energy can be explained by opening of the ten- sile fractures and spall.

Development of an accelerating piston implosion-driven launcher

The ability to soft-launch projectiles to velocities exceeding 10 km/s is of interest for a number of scientific fields, including orbital debris impact testing and equation of state research. Current soft-launch technologies have reached a performance plateau below this operating range. In the implosion-driven launcher (ILD) concept, explosives are used to dynamically compress a light driver gas to significantly higher pressures and temperatures than the propellant of conventional light-gas guns. The propellant of the IDL is compressed through the linear implosion of a pressurized tube. The imploding tube behaves like a piston which travels into the light gas at the explosive detonation velocity, thus forming an increasingly long column of shock-compressed gas which can be used to propel a projectile. The McGill designed IDL has demonstrated the ability to launch a 0.1-g projectile to 9.1 km/s. This work will focus on the implementation of a novel launch cycle in which the explosively driven piston is accelerated in order to gradually increase driver gas compression, thus maintaining a relatively constant projectile driving pressure. The theoretical potential of the concept as well as the experimental development of an accelerating piston driver will be examined.

Simple correlation for predicting detonation velocity of ideal and non-ideal explosives

This paper describes a simple method for prediction of detonation velocity of ideal and non-ideal explosives. A non-ideal aluminized and nitrated explosive can have Chapman–Jouguet detonation velocity significantly different from that expected from existing thermodynamic computer codes for equilibrium and steady-state calculations. Detonation velocity of explosives with general formula C a H b N c O d Al e can be predicted only from values of a, b, c, d, e and a specific structural parameter without using any assumed detonation products, heat of formation and experimental data. Predicted detonation velocities by this procedure for ideal and non-ideal explosives show good agreement with respect to experimental values as compared to computed results of BKWR and BKWS equations of state.