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Data on the parameters of explosion and detonation of two- and three-fuel mixtures of methane, coal dust, and hydrogen (with oxygen and air) with varied fractions of the fuels are reported. The novelty of the numerical and graphical data arrays is due to previously unknown data on the critical energy of detonation initiation, characteristic size of detonation cells, detonation velocity, and energy release in detonation waves. The analysis is performed not only for stoichiometric two- and three-fuel systems, but also for rich and lean systems based on the fuels under study. [ABSTRACT FROM AUTHOR]

Detonation waves in gaseous two-fuel systems CH4/H2/O2 and heterogeneous three-fuel systems CH4/H2/O2/coal suspension are experimentally studied. The experiments are performed with coal particle sizes m and mean-volume densities of 160–400 g/m3. The velocities along the tube and the pressure profiles in incident detonation and reflected waves are measured. The influence of the fuel components on the wave parameters is analyzed. The experimental detonation parameters are compared with the predicted thermodynamic equilibrium detonation parameters. [ABSTRACT FROM AUTHOR]

The combustion, explosion, and detonation in hybrid systems containing gas mixtures of CH4/air, CH4/O2, and O2/coal particles up to 200 μ m in size with a volume-averaged density of up to 700 g/m3 were studied on a vertical shock tube. X-ray diffraction patterns of the initial coal powder and coal samples subjected to high-temperature waves were analyzed. Data were obtained on the structure and parameters of waves in hybrid mixtures and in the same gas mixtures without coal dust. It is shown that in hybrid systems, coal dust has a weaker influence on the parameters of combustion and detonation waves than methane and that methane in these waves is more reactive than coal dust. [ABSTRACT FROM AUTHOR]

Precise prediction of blast-induced ground vibration is an essential task to reduce the environmental effects in the surface mines, civil and tunneling works. This research investigates the potential of imperialist competitive algorithm (ICA) in approximating ground vibration as a result of blasting at three quarry sites, namely Ulu Tiram, Pengerang and Masai in Malaysia. In ICA modeling, two forms of equations, namely power and quadratic, were developed. For comparison aims, several empirical models were also used. In order to develop the ICA and empirical models, maximum charge weight used per delay (W) and the distance between blasting sites and monitoring stations (D) were utilized as the independent variables, while, peak particle velocity (PPV), as a blast-induced ground vibration descriptor, was utilized as the dependent variable. Totally, 73 blasting events were monitored, and the values of W, D and PPV were carefully measured. Two statistical functions, i.e., root mean square error and coefficient of multiple determination (R2) were used to compare the performance capability of those prediction models. Simulation results show that the proposed ICA quadratic form can get more accurate predicting results than the ICA power form and empirical models. [ABSTRACT FROM AUTHOR]

Accidents in underground collieries, under geological and geotechnical uncertainties, cause some irrecoverable consequences for workers. Recognizing and studying the effective factors in the occurrence of such accidents have a very crucial impact on improving worker safety and reducing mining costs. This paper introduces a new and beneficial technique named 'modified risk priority number (MRPN)' for recognizing and assessing those risks which may cause working accidents in Iranian underground collieries. The available qualitative data from the mines was quantified using standard tables established for risk assessment. The technique was exemplified using data from mine accidents in Kerman and East-Alborz regions. Roof-fall was found to be the most significant risk factor in the mines that were investigated. [ABSTRACT FROM AUTHOR]

As an explosion control measure, rock dusting has been used in underground coal mines in many major coal producing countries with different standards. The effectiveness of the rock dust in reducing explosion intensity has been proven by historic events and laboratory experiments. The main functions of rock dust in controlling mine explosions (i.e., isolator, physical heat sink and chemical energy absorber) have been quantitatively studied and results are presented in this paper. [ABSTRACT FROM AUTHOR]

As the mining depths increase, an increasing number of mines in China encounter a new type of integrated dynamic disaster of rockburst and water inrush, causing great casualties and economic losses. This occurs constantly due to lacking understanding of its occurrence mechanism. This study investigated the mechanism of rockburst and water inrush as a new type of integrated dynamic disaster that has occurred in several mining areas in China. Mechanism of rockburst and water inrush mutually induced was proposed. A theoretical formula for vertical stress and floor failure depth was established and the formula indicates that dynamic stress increase lead to the floor failure depth increase, meanwhile, the thickness of aquiclude decrease. Microseismic monitoring technology was used to examine the effect of dynamic stress induced by overlying strata movement on floor failure and the results showed that the depth of microseismic events in coal floor reached the maximum 28 m when the dynamic stress reached the maximum. The finite element method was used to verify the effect of dewatering on stress distribution and the displacement of surrounding rock, and the results indicated that dewatering leads to the formation of the overlying strata settlement, vertical stress decrease in the region above the area, and vertical stress increase in the boundary region of water-rich area. [ABSTRACT FROM AUTHOR]

The determination of explosibility is critical for mine rescues or controlling the severity of a mine accident, especially for the gas explosion event. After a severe coal mine fire or an explosion event, a common practice for minimizing the risk is to seal the related area, and then to inject the inert gas (N and/or CO) into the sealed area to extinguish the fire and prevent potential explosions. At the same time, rescue works will be immediately planned. In order to avoid the risk associated with a potential secondary explosion, the rescue workers are not allowed to go underground until the atmosphere of the sealed area no longer has the possible explosibility. Therefore, mining engineers must precisely know how dangerous the current situation is and what is the risk degree. One explosibility method, the Coward explosibility diagram, can clearly identify the explosive status of a mine atmosphere and track its explosibility trend as the compositions of mine atmosphere change. However, the Coward diagram can only identify the mine gas explosibility, but it lacks the ability showing the safety margin. In this paper, a new concept, explosibility safety factor (SF), is introduced and defined to improve the safety for the rescue works when using the Coward method. It can clearly show how dangerous the current atmospheric status is if the state point locates in any not-explosive zones and also provide a measurement method to scale the safety margin when dealing with the explosibility of a sealed mine atmosphere. Application of this factor is also demonstrated at the end of the paper. [ABSTRACT FROM AUTHOR]

The developed pattern of calculation for the parameters of drilling and blasting in boreholes and shotholes is based on a charge design with reduced amount of explosive at the top. The calculation takes into account the action time of the explosion-generated pulse conditioned by outflow of detonation product gases. The authors have derived relations for such rational parameters of drilling and blasting that minimize costs of drilling at the same quality of rock fragmentation. [ABSTRACT FROM AUTHOR]

In 2009, a serious gas explosion happened in Tunlan coal mine at Shanxi province, P.R. China, which claimed the lives of 78 miners. One hundred and fourteen miners got injured, and nearly 4 million dollars of economic loss was reported. On the surface of it, it seems to be an independent happened accident. However, the formation of a gas explosion is dependent on various conditions and all these conditions must be met at the same time so as to result in such explosion. Hence, the explosion itself is not a single event in time. With considering the gas explosion causing the mine ventilation system failure, there must be a number of related causations existing in the system which play important roles that contribute to the system failure. In other words, explosion can be considered as an evolution resulting from various related other failures in the system. Hence, in this paper, failure modes and their contributions to the explosion are going to be investigated. Based on the requirements of an explosion and its propagation characteristics in the underground roadway network, this paper summarizes all failure modes in the gas explosion accident through the initial formation of explosion to its post effects. Moreover, using the theoretical approach and simulation method, the corresponding contributions are also interpreted. The research efforts show that (1) it should not simply treat the explosion as an independent event. Various linked failure modes can be observed during the analysis. It is a quite interesting and also needed for mining engineers to well understand their formations and effects on the system, which may greatly improve the system design in the future to avoid such accidents and (2) the domino effect is involved in various failure modes. It also provides a solution to stop the accident's propagation by breaking any chain reactions. The research results presented in this paper can be used as theoretical guidelines for improving the safety considerations of a mine ventilation system design work in the future practices. [ABSTRACT FROM AUTHOR]

The heat sinks are utilized in electronic devices to eliminate heat from the chip and efficiently transmit it to the environment. Therefore, the optimal geometry sizes of fin heat sinks are the point of concern for manufacturers and designers. For this reason, the importance of optimization techniques particularly metaheuristics is understood. The design variables are width of heat sink, number of fins, fin height, and fin diameter. The various responses that have been considered are electromagnetic emitted radiations, thermal resistance, and mass of the heat sink investigated separately and simultaneously (multi-objective). Mine blast algorithm (MBA), as a recently developed optimizer, is inspired from explosion of mines. The optimum dimensions and values for each response have been obtained by the MBA and have been compared with other optimization methods in the literature. In terms of thermal resistance and mass responses, the MBA has offered better values, while for the emitted radiations, the obtained results obtained by Taguchi-based gray relational analysis (TGRA) was preferred. For manufacturing point of view, the MBA and TGRA both suggested better and efficient design. In addition, the value path analysis has been carried out to compare the trade-off among the considered responses. Finally, parametric sensitivity analyses have been implemented for design parameters, and discussions and comparisons have been carried out for the effects of each decision variable. By considering all responses, width of heat sink and fin height are considered as the most important and effective design parameters, respectively. [ABSTRACT FROM AUTHOR]

Based on the description of the commercial test results, it is shown that the turbo-blasting with linear priming of granular explosive charges allows resetting the blasting-raised bench bottom to the design position within a single cycle of drilling-and-blasting and with the decreased powder factor. [ABSTRACT FROM AUTHOR]

The article presents a study which investigates the detonation initiation in a stoichiometric natural gas air mixture with a focusing nozzle in power plant process. The study used pulsed detonation (PD) combustion of natural gas and initiation of deflagration-to-detonation transition (DDT). The result shows the importance of using PD combustion of natural gas in understanding dynamics of accidental gas explosions in mine working that will increase the power plant efficiency and capacity process.

In this research, experimental applications have been performed to reduce blast induced vibrations in open pit mines. For this purpose, artificial discontinuity zones such as barrier holes and trench were opened in a dragline panel of Seyitomer Lignite Enterprise, Kutahya, Turkey. Peak particle velocities in front of and behind them were measured by seismographs. In this way, their effect against vibration was observed and compared. Barrier holes were opened 24 m deep through 3 parallel lines and aligned at 1 m spacing. On the other hand, the trench had 8 m depth and 4 m width. During the research, 209 measurements were taken belonging to 105 explosions. Twenty-eight explosions were carried out in the barrier holes experiments and 77 explosions were carried out in the trench experiments. A decrease in vibration of 14.3–18.5% was obtained behind the barrier holes while a decrease of 24.8–58.1% was provided by the trench. [ABSTRACT FROM AUTHOR]

The calculation scheme of rock failure under explosion of a borehole charge is presented with account for density of borehole filling with an explosive, availability of air and inert intervals. According to the calculated data, the introduction of air intervals diminishes the specific explosive consumption by 9–27% depending on the explosive power intensity. The similar effect is gained by introducing an inert rod into a borehole charge. [ABSTRACT FROM AUTHOR]

It is studied how a crack develops in an infinite massif under explosion of a cylindrical charge having a finite length. Numerical solution of a 3-D elastic-brittle problem has yielded relationship of the final shape of the crack, force of explosion, strength of the massif and the charge parameters. It is shown that the longer the charge, the higher disruptive effect it produces. [ABSTRACT FROM AUTHOR]

The mechanism of controlling the blast energy of contiguous charges by their modifications of the same construction is considered for satisfying the conditions and requirements of mining technologies for explosion. [ABSTRACT FROM AUTHOR]

The results are presented for the experimental and theoretical investigations into behavior of casing string and cement ring of a well under the action of internal cylindrical charge explosion. It is shown that the developed calculation procedure can be used for analyzing the possible failure of well casing. [ABSTRACT FROM AUTHOR]