Consumption Of Explosives Research Articles

Research on the mechanism and application of wedge cutting blasting with hole-inner delay

To increase the efficiency of deep-hole blasting driving in mine rock tunnels, an innovative pattern of wedge cutting blasting with hole-inner delay was proposed. First, the blasting mechanisms of conventional and innovative wedge cutting patterns were theoretically investigated. The results showed that the resistance from large upper rock blocks and the clamping action from the surrounding rock were the major challenges of conventional cutting methods. For the innovative cutting pattern, under the conversion of the spatial distribution and release sequence of blasting energy, the first blasting of the upper charge can strengthen the breaking of the upper rock mass and create a new free surface, which provides favorable conditions for the delayed blasting of the bottom charge. Second, finite element models of two cutting patterns were established and solved, and the simulation results visually revealed the propagation of a stress wave. Critically, the stress strength in the upper cavity increased by 66–83% under the action of the upper charge, which was conducive to the breaking of the upper rock mass and the generation of a new free surface. Therefore, the rock mass in the bottom cavity can be readily broken and discharged. Ultimately, field applications were executed in a rock tunnel. Compared with a conventional cutting pattern, the proposed innovative cutting pattern can prominently increase the cycle advance and hole utilization and greatly reduce the unit consumption of explosives and detonators. This research confirms the usability of the innovative wedge cutting pattern with hole-inner delay in deep-hole blasting driving of rock tunnels.

Optimization Study of Water Interval Charge Structure Based on the Evaluation of Rock Damage Effect in Smooth Blasting

In tunnel smooth blasting, optimizing the water interval charging structure of peripheral holes is of great significance in improving the effect of smooth blasting and reducing the unit consumption of explosives. Addressing the issue of a single traditional evaluation standard, this paper proposes a composite index evaluation method for rock blasting damage in different zones, and the best charging structure is optimized according to the evaluation results. Taking Liyue Road Tunnel Light Smooth Blasting Project in Chongqing as the Research Background, the numeric models were established with ten kinds of charge structures, the charge structures and explosive quantity were optimized according to the evaluation results, and then the field tests were conducted. The results show that when the length of the water medium at the bottom of the hole is 20 cm, the damage range of the retained rock mass can be controlled while ensuring rock fragmentation. If the length of the water medium at the orifice and in the center of the hole is more than 30 cm, it will affect the superposition effect of the blast stress wave, resulting in under-excavation; in the preferred charge structure, the ratio of the length of the upper and lower explosives reaches 1:3, and the ratio of the length of the water medium is 2:2:1, which achieves a better rock-breaking effect in the field test.

РАЗРУШЕНИЯ МАТЕРИАЛОВ ЗАРЯДАМИ УДАРНО-ВОЛНОВОЙ РЕЗКИ ПОД ВОДОЙ В ЧРЕЗВЫЧАЙНЫХ СИТУАЦИЯХ

The paper assesses the effectiveness of shock-wave technology cutting for rocks. A comparison of materials cutting technologies using a shock-wave and a shaped charge is done. Shows a significant reduction in the consumption of explosives and an increase in efficiency
 in shock-wave cutting with a simultaneous reduction in safe distances. Solving the problems of underwater explosions in the interests of rescue operations in emergency situations.

Минимизация риска загрязнения селитебных зон пылью при открытой добыче руд

The sphere of activity of the mining and metallurgical complex of the Kursk Magnetic Anomaly included populated areas and agricultural objects. An air dusting zone with a radius of tens of kilometers was formed around openpit mining pits. During explosions in quarries, dust clouds are formed, from which fine mobile dust is dispersed. Therefore, the regions of the Kursk magnetic anomaly are characterized by the accumulation of chemical elements, including hazard classes 1–2. The dustiness factor in ecosystems complicates the living conditions of the population, which experiences the chemical effect of natural leaching of ore mining and processing products. Disturbance in the balance of the pro-oxidant-antioxidant system can cause a variety of diseases. A radical measure to prevent disease is to reduce the volume of mobile dust during ore mining in quarries. The parameters of rock destruction by explosion depend on the crushing energy intensity, above which the action of the charges goes into the ejection zone with the formation of mobile dust. Increasing the height of the ledge reduces the energy intensity of the explosion (by reducing the consumption of explosives) and the release of mobile dust. Both convective and diffusion processes occur in a dust cloud. Quarry emissions contain metals that form toxic compounds that cause soil degradation. The reaction of living matter to the effects of pollutants is predictable, which can be the basis for regulating the state of the environment. Improving the living conditions of the biota and population in the vicinity of mining sites can be achieved by adjusting the ore mining technology. To reduce the yield of mobile dust, a combined scheme of explosive ore breaking with differentiation of the process of destruction of the base of the ledge and the main mass is recommended.

ОПТИМИЗАЦИЯ ПАРАМЕТРОВ ТЕХНОЛОГИИ РАЗРАБОТКИ ПОЛУСКАЛЬНЫХ ВСКРЫШНЫХ ПОРОД ЭКСКАВАТОРНОАВТОМОБИЛЬНЫМИ КОМПЛЕКСАМИ С ПРИМЕНЕНИЕМ МЕХЛОПАТ

The article presents the results of research on the optimization of the parameters of the technology for the development of semi-horizontal overburden by excavator-automobile complexes using mechlopats. The available methods for calculating the productivity of mechlopats are analyzed. An empirical universal dependence of the calculation of the value of the excavation coefficient on the average diameter of the piece has been established for all types of modern mechanical shovels, which makes it possible to determine the change in the value of the replaceable operational performance of mechanical shovels from the value of the average size of pieces of blasted rocks. The results of statistical processing of comparing the values of the excavator performance installed in production conditions with the calculated ones showed that the coefficient of variation when calculated according to the proposed (new, universal) formula is almost two times lower than the known (used) ones. An enlarged block diagram of a complex algorithm for optimizing the parameters of the EACMS is determined by selecting the value of the specific consumption of explosives, the type of a mechanical shovel, dump truck, drilling rig and bulldozer.

Investigation of the Process of Destruction of a Roain Massif by Borehole Charges with an Axial Air Cavity by the Method of Physical Simulation

the design of downhole explosive charges with an axial air cavity was developed, which ensures uniform crushing of the rock mass and reduces the specific consumption of explosives. A technique has been developed for modeling the process of destruction of a rock mass by borehole charges with an axial air cavity. It has been established that with an increase in the diameter of the axial cavity, the mass of the charge and the specific consumption of explosives for breaking decrease. However, this decrease occurs only up to a certain limit, after which the volume of the chipped mass decreases and the specific consumption of explosives increases. The most efficient way is to reduce the specific consumption of explosives for breaking when the ratio of cavity diameters and charge diameters is 1.3:5–2.2:5. For other values of the ratio, the specific consumption of explosives increases dramatically.

РАЗРУШЕНИЯ ПОРОД И МАТЕРИАЛОВ ЗАРЯДАМИ НА ОСНОВЕ ТЕХНОЛОГИИ УДАРНО-ВОЛНОВОЙ РЕЗКИ ПРИ ЧРЕЗВЫЧАЙНЫХ СИТУАЦИЯХ

The paper assesses the effectiveness of shock-wave technology cutting for rocks and materials. A comparison of materials cutting technologies using a shock-wave and a shaped charge is done. Shows a significant reduction in the consumption of explosives and an increase in efficiency in shock-wave cutting with a simultaneous reduction in safe distances. Solving the problems of underwater explosions in the interests of rescue operations in emergency situations.

Study on explosive welding of Cu/steel composite pipe under local water environment

AbstractIn order to improve the energy utilization rate and the bond quality of explosive welding, the local water environment method is used in present study. In this paper, several groups of high‐quality Cu/Steel explosive composite pipes are prepared under local water environment. Optical microscope and mechanical property tests are conducted to analyze samples microstructure and mechanical properties. The results show that the waveform dimension of Cu/Steel bonding interface has a positive correlation with explosive layer thickness, and the miniature wavy bonding interface with the highest bonding quality is obtained by using the local water environment method. Compared with the traditional charge method, the consumption of explosives for the local water environment charge method is decreased about 60 % in the same case of experimental conditions. The local water enviroment method solves the problem of ablation damage at the contact surface between metal and explosives, and effectively reduces the diameter expansion phenomenon and end damage caused by boundary effect in the welding process. Through mechanical property tests, it was found that the yield strengths and compressive strengths of Cu/Steel specimens which created by the local water environment method are positively correlated with the explosive thickness.

Optimization of blasting parameters and prediction of vibration effects in open pit mines based on deep neural networks

Embedded systems in production equipment and Internet of Things (IoT) sensors on production lines are one of the elements that constitute an industrial cyber-physical system. In this paper, an in-depth study and analysis of the optimization of blasting parameters and prediction of vibration effects in open pit mines using deep neural network arithmetic are present. Based on the deep neural network research and analysis of the relationship between blasting parameters and rock fragmentation, a prediction model for blasting parameters and fragmentation for the East Open Pit Mine was established, and sensitivity analysis was performed on blasting parameters, and the unit consumption of explosives and the perforation rate were established. It was found that the average relative errors of both numerical simulation results and depth prediction results were no more than 10%, while the average relative errors of Sadowski's formula prediction results were more than 20%. The results show that the neural network optimized by a genetic algorithm and the numerical simulation has the highest accuracy in predicting the blasting result parameters. The research model and results obtained in this paper can be used as a reference guide for engineering practice.

Исследования техногенного воздействия взрывного разрушения горных пород при освоении месторождений полезных ископаемых открытым способом

The topicality of this research is defined by the increasing volume of mining operations near settlements and production infrastructure, as well as by the increasing unit capacity of mining and haulage equipment and, consequently, by the growing volume of rock mass simultaneously blasted and prepared for excavation. Changes in the mining conditions at the operations of UK Kuzbassrazrezugol JSC have been analyzed. A brief analysis of research results on various factors affecting the degree of man-made impact of the blasting operations is presented. One of the ways to safely increase the volume of simultaneously blasted rock mass is the introduction of energy-saving environmentally friendly technologies in production and use of plastic explosives, which would ensure higher completeness of chemical transformations and the efficiency of the blast through the use of special fuel mixtures containing surfactants instead of diesel fuel in the compositions of granular industrial explosives. This will increase the contact surface area of the fuel and the oxidizer by several orders of magnitude as well as the stability and the energy-output ratio of the blasting charges with the zero oxygen-combustible balance. Reducing the consumption of explosives, energy intensity of mining, the man-made impact of blasting operations on the environment, the seismic action of the blast, the radius of the hazardous zone - all of this can be achieved by using charges placed in hoses of variable diameter when blasting wet and dry rock masses. The article shows the dependence of changes in the load on the atmosphere with increasing distance from the blast epicenter and with increasing weight of simultaneously detonated explosives in surface mining operations, as well as the dependence between the yield of fines and the size of the gap between the charge and the charging chamber.

Обоснование эффективности взрывных работ с использованием электронных систем в сравнении с неэлектрическими средствами инициирования

Carrying out large-scale blasting using non-electric primers in surface mining is concerned with a number of deficiencies, one of which being the error in borehole and surface delay times. As a consequence, the design blasting system is compromised, the face blasting rates are affected, and the rock mass fragmentation quality goes down. Due to their advantage in the triggering accuracy, the electronic blasting systems ensure absolute control over the execution of large-scale blasting, reduce the negative impact of blasting operations on residential areas near the surface mine and improve the quality of rock mass fragmentation. Electronic blasting systems enable the development of new ways to execute blasting, for example, though selecting the face blasting rates, which in turn increases the rock mass fragmentation quality and reduces dilution. The paper presents comparative indicators of bias in the nominal delay times of various non-electric primers and electronic blasting systems, discusses the components and designs of electronic detonators, and provides a number of advantages of the electronic systems in conditioning of the the preparation of blasted rock. A conclusion is made that blasting with electronic detonators and the use of their advantages will help to reduce the specific consumption of explosives and the scope of drilling operations due to larger blasthole patterns.

Layout method and numerical simulation study of reduced-hole blasting in large-section tunnels

The traditional tunnel-drilling and blasting parameter design is based on the small-section roadway and involves many boreholes and conditions that require slow operation progress and thus cannot meet the rapid operation requirements of a large-span tunnel. Taking the Baizhushan Tunnel as the engineering background, this article put forward a theoretical basis for a hole-reducing layout method for large-section tunnel blasting. These parameters of the rock statics and dynamics were obtained through core-drilling sampling in the field and the development of static and dynamic tests. LS-DYNA software was used to establish the numerical model of large-span tunnel blasting. The method was verified through three aspects, namely, cavity effect, effective stress, and surrounding rock damage and was implemented in the field application. The results showed the following: the scheme for reducing-hole numbers used 26 fewer blast holes per cycle footage and saved 0.7 h of drilling time; the average effective stress of the retained rock was 0.6 times that of the original blasting scheme, which reduced the damage to the remaining rock; the maximum over-excavation thickness control was within 50 cm, which reduced over-break; in the field test, the utilization rate of cutting holes was 81.9%, the utilization rate of other blasting holes was 91.2%, the unit consumption of explosives was 0.72 kg/m3, the average over-excavation thickness control was within 20 cm, and the smooth blasting effect was superior.

Controlling blast energy parameters to ensure intensive open-pit rock fragmentation

Controlling blast action, in order to increase its energy efficiency in a production blasthole is quite an important issue. This is because it enables the formation of broken rock mass with preset coarseness parameters. Increasing the blast pressure and the time of the blast impact on a rock mass is traditionally recommended as one of the ways to improve the blast action on the rock mass, thus reducing the oversize yield in open pits. One device which enables this approach to a certain extent is a turbulator. The turbulator is fabricated of aluminum plate twisted in a helical fashion around its longitudinal axis. It is mounted in a production blasthole according to a specially designed scheme. The methodology developed to study the stress and strain state of a rock mass when using a turbulator in a blasthole explosive charge allows the size of radial fracture zone and the radius of rock fragmentation to be defined. A method was developed to initiate blasthole charges in a pit blasting block. It includes drilling blastholes, filling them with explosive, installing downhole blasting caps, and blasting using non-electric initiation system. A blasting block is divided into two equal parts (sections), which in turn contain three series of blastholes for short-delay blasting. Blasthole charges are initiated simultaneously in the two parts of the block based on a trapezoidal blasting pattern, thus ensuring meeting detonation waves. In the first series, instantaneous blasting of blastholes located on both ends of the blasting block and forming a trapezoid (in plan view) is carried out. Then after 42 ms, the second series of blastholes (also forming a trapezoid) is detonated. After another 42 ms, the remaining blastholes are detanoated along the perimeter of the blast block in the third series. Implementation of this design with the effect of turbo-blasting for rock fragmentations by blasthole charges at the Kalmakyr deposit of JSC “Almalyk Mining and Metallurgical Complex” has led to the reduction of consumption of explosives, volume of drilling, secondary fragmentation costs, and increased productivity of excavators and mining safety.

STUDY OF THE INFLUENCE OF THE WIDTH OF THE STOPE ON THE CHOICE OF DRILLING AND BLASTING PARAMETERS IN THE DEVELOPMENT OF THIN DEPOSITS

The article presents the results of a study of the influence of the width of the stope on the choice of drilling and blasting parameters in the development of thin veins of the Akbakay field. The dependences of the specific consumption of explosives and borehole meters on the width of the face are established.

Обоснование области и опыт применения однорядного взрывания в условиях повышенных требований к качеству полезного ископаемого

The paper justifies the application area of single-row blasting at nonmetallic deposits characterized with a complex structure and low cost of mineral resources, but with a high value of recoverable fractions. It describes the reasons for decreasing value of the end products mined in quarries developing marble reserves to produce microcalcite. Ways of upgrading the quality characteristics of rock preparation for excavation using single-row blasting are described for conditions of increased requirements towards the quality of minerals. Drilling and blasting plans are developed to achieve the required quality characteristics of rock crushing. A simulation of single-row blasting in conditions of varying parameters of the borehole grid and specific consumption of explosives has been carried out. The article presents the results of pilot blasting as well as technical and economic comparison of multi-row and single-row blasting in terms of maximized profitability of the mining company and minimized cost of the end product. The parameters of the mining system that are changed when single-row blasting is used are indicated.

Assessing the explosion effect on rock mass pre-destruction

Introduction. Theoretical and empirical research into rock blasting proved that detonation wave propagation results in the development of destruction and pre-destruction zones around the explosive cavity. In the destruction zone, rock crushes. In the pre-destruction zone, stresses set up by the detonation wave are concentrated on rock mass structure defects, giving rise to new micro defects and the development of the existing ones. Rock fracturing and cavitation increase, lowering its strength properties; this is called rock pre-destruction. There are works devoted to the qualitative analysis of rock in the pre-destruction zone, but the problem requires elaboration to offer possibilities for practical application. Research aims to quantify rock mass pre-destruction to use the parameters of rock blasting by borehole charges under opencast mining in engineering calculations. Methods of research. To assess the degree of rock mass pre-destruction at a distance from the charge axis, a pre-destruction intensity coefficient is used. The destruction zone radius is determined by a well-known method. In the destruction zone, the value of the pre-destruction intensity coefficient is higher than one, i. e. there is discontinuity of the rock mass. Beyond the destruction zone, there is a pre-destruction zone where the value of the pre-destruction intensity coefficient is less than one. The pre-destruction zone boundary is at distances of the order of 200–250 charge radii. The pre-destruction intensity coefficient of a particular zone attained after all charges have been fired is determined by summing the pre-destruction intensity coefficient from every charge. According to the energy approach, rock strength can be assessed by the value of the specific drilling energy intensity. In order to determine the reduction value of the specific drilling energy intensity in a particular zone, it is essential to know the drilling specific energy capacity of this zone in the natural state, the pre-destruction intensity coefficient attained after a large-scale blast of borehole charges, and specific drilling energy intensity of completely disintegrated rock. The effect made by another borehole charge explosion on the rock mass is weaker due to its pre-destruction by previous blasts. So we propose the impact multiplicity coefficient that reflects the accumulation of pre-destruction in a particular zone under the sequence blasting of borehole charges. Results. The expected value of the specific drilling energy intensity has been calculated for the individual arbitrarily spaced wells within the pre-destruction zone of a particular rock mass zone. The calculation results were compared with the practical values measured during blasting preparation in the preset rock mass zone. Conclusions. The findings of this study have made it possible to quantify the impact of explosions on rock mass pre-destruction. The developed technique makes it possible to predict the value of drilling energy intensity in the pre-destruction zone and, as a result, establish the required specific energy intensity of detonation and hence the consumption of explosives. Thus, it becomes possible to reduce the consumption of explosives under the existing blasting scheme at the enterprise and model other charge initiation types to select the least expensive one.

A review on the prediction and assessment of powder factor in blast fragmentation


 
 
 Powder factor can be defined as the quantity of explosives (kg) required to break a unit volume or tonne (t) of rock. The prospect of excavating rocks by blasting is characterized by a specific consumption of explosives. In the past decades, researchers have come up with several precise approaches to predict powder factor or specific charge in blast operations other than through trial blast. Research in this area has focused on the relationship between rock mass properties, blasting material and blasting geometry to establish the powder factor. Also, the interaction between specific energy and particle size embodied in the theory of comminution that is less dependent on local conditions has been studied. In this paper, the various methods for powder factor estimation based on empirical and comminution theory modelling as well as machine learning approaches in both surface bench blasting and underground tunnel operations have been reviewed. The influence of intact rock properties on powder factor selection and the influence of powder factor selection on post-blast conditions have also been discussed. Finally, the common challenges that have been encountered in powder factor estimations have been pointed out in this regard.
 
 

Empirical regularities investigation of rock mass discharge by explosion on the free surface of a pit bench

Minimizing the discharge of blasted rock mass into the developed space of the pit is a very relevant area for study, as it allows to increase the processability of work and reduce the cost of mining. The article presents the results of experimental industrial explosions, during which the study of this issue was conducted. The main purpose of the work was to establish the key factors affecting the volume of rock mass discharge to the pit haulage berm. During the analysis of the world experience of research on this topic, the key factors affecting the formation of collapse and discharge – natural and technological – are identified. The method of conducting experiments and collecting data for analyzing the influence of technological parameters of location, charging and initiation of wells on the volume of rock mass discharge is described. It is established that the main discharge to the pit haulage berm is formed by the volume of rock mass limited by the prism of the slope angle. With a sufficient rock mass displacement from the edge of the bench crest towards the center of the block, only the wells of the 1st and 2nd rows participate in the discharge formation. Empirical dependences of the total volume of rock mass discharge on the length of the block along the bench crest, the specific consumption of explosives, the size of a rock piece P50 and the rate of rock breaking are obtained. The obtained results can be used to design the parameters of the drilling and blasting operations (DBO), as well as to predict and evaluate the possible consequences of a mass explosion in similar mining and geological conditions.

INCREASING THE EFFICIENCY OF BLASTING WORKS IN THE QUARRY OF BUILDING MATERIALS

The article is devoted to the urgent problem of increasing the efficiency of blasting operations in open pits in conditions of high water saturation of minerals.
 The idea of solving this problem is to use the effect of draining the local area of the water-saturated block of the mineral due to the ordinal explosion of the well charge. 
 The purpose of this study was to improve the efficiency of blasting operations on flooded fractured rocks in open pit mining.
 Research methodology. The proposed technique makes it possible to determine the parameters of drainage of the watered mass during the explosion of borehole charges and the parameters of an ordinal explosion. This makes it possible to improve the quality of rock crushing and reduce the consumption of explosives per unit cost.
 The main direction of research in this work is to reduce the energy intensity of the process of destruction of a water-saturated mineral by using the internal potential of water in the cracks of the massif destroyed by the explosion. The regularities and the role of the drainage funnel in the efficiency of destruction have been established.
 The novelty and originality of the work is a developed technology for removing water from the explosion zone, which increases the efficiency of explosion and destruction of rocks using special water-resistant explosives.
 The practical value of the work lies in the effectiveness of the proposed method for carrying out blasting operations, which, along with improving the quality of crushing, provides an increase in the output of blasted rock mass from one running meter of the well and reduces the cost of expensive water-resistant explosives.
 Conclusions. The introduction of research results and recommendations in open pits made it possible to increase the efficiency of blasting operations in the development of water-saturated rocks. Energy consumption for the destruction of an array of water-saturated minerals is reduced by 10%. The amount of blasted rock mass per running meter of the well increased by 14.1%, and the specific consumption of explosives decreased by (12-14) %. 
 
 Keywords: quarry, minerals, well, filtration, water-saturated massif, crushing, explosive, detonation.

Emerging trends in drilling and blasting technology: concerns and commitments

In conventional blasting when explosive is detonated, it releases huge amount of effective and non-effective energies that can produce gas and shock accompanied by light, heat, sound and pressure. The effective energy can act as a useful tool in breaking rock for mining and construction purposes. However, the non-effective energy can cause disastrous effects and huge destruction to human lives and the surrounding environments. The most common safety concerns and undesirable side-effects include ground vibrations, flyrock, noise, premature explosion and air/dust pollution. However, they can be well-controlled with proper blast design using precise delay timing, direction of throw, distribution of explosives inside the blastholes and selection of explosives in close matching with the characteristics impedance of rock, etc. in order to meet safety and environmental needs at a minimum operating cost with optimum utilisation of rock deposits. It is established that explosive utilisation can be reduced using airdecks at strategic locations of the blastholes and 30% or even more effective cast ratio (ECR) is possible in specific cases of dragline and shovel-dumper faces. In case of clean coal extraction from a coal seam having thin partings of 0.5 to 1.2 m, segregation blasting has shown to be an effective tool wherein the concept of projectiles of the blasted materials depended on energy utilisation at different rock layers of varying densities. The method of induced blasting, may it be from surface or underground, has become a proven approach during depillaring operations in blasting gallery, longwall mining and mechanised mining with continuous miners. It needs perfect design and optimum consumption of explosives from safety standpoints. All these emerging technologies have arisen as a result of intense field experiments carried out by the global researchers. It is therefore felt necessary to give a brief account of such technologies to partially fulfil the commitments posed by the mining professionals for safe extraction of coal and minerals under constrained conditions.