Implementation of explosion safety regulations in design of a mobile robot for coal mines

The article focuses on specific challenges of the design of a reconnaissance mobile robotic system aimed for inspection in underground coal mine areas after a catastrophic event. Systems that are designated for these conditions must meet specific standards and regulations. In this paper is discussed primarily the main conception of meeting explosion safety regulations of European Union 2014/34/EU (also called ATEX-from French "Appareils destines a etre utilises en ATmospheres Explosives") for Group I (equipment intended for use in underground mines) and Category M1 (equipment designed for operation in the presence of an explosive atmosphere). An example of a practical solution is described on main subsystems of the mobile robot TeleRescuera teleoperated robot with autonomy functions, a sensory subsystem with multiple cameras, three-dimensional (3D) mapping and sensors for measurement of gas concentration, airflow, relative humidity, and temperatures. Explosion safety is ensured according to the Technical Report CLC/TR 60079-33 "s" by two main independent protections-mechanical protection (flameproof enclosure) and electrical protection (automatic methane detector that disconnects power when methane breaches the enclosure and gets inside the robot body).Web of Science811art. no. 230

A quantitative approach to engineering fire life safety in modern underground coal mines

Emerging from a history of blanket approach prescriptive fire protection design, underground coal mining is rapidly embracing fire life safety analysis techniques that have been successfully used in performance-based fire engineering in the built environment. In Australia, the leading practice fire engineering approach is to apply the International Fire Engineering Guidelines (ABCB 2005) and its methods as a design assessment framework. This approach has recently been used to quantify the performance of mine fire detection and therefore control of fire spread, paving the way for improvements in mine fire intervention and mine worker escape. This paper presents a method of early fire detection using closed circuit television cameras and video analysis software associated with fixed plant fires leading to increased available safe evacuation time compared with contemporary point type fire detectors and gas monitoring sensors. Successful pilot tests of the fire detection technology have been carried out in simulated mine conditions. A quantified and scientifically informed risk-based approach, offering improvements in mine fire rescue intervention and evacuation methodologies was achieved

Study on Energy Accumulation and Dissipation Associated with Coal Burst

Coal burst, which refers to the brittle failure of coal, has been a serious hazard for underground coal mining, particularly at greater depth. Massive energy accumulated in coal could be dissipated almost instantaneously in the form of kinetic energy when the loading stress exceeding the ultimate strength of coal. This thesis qualitatively and quantitatively examines the energy accumulation and dissipation process associated with coal burst through a comprehensive research program of literature review, theoretical analysis and experimental studies. The energy accumulation sources, dissipation forms and its influencing factors of coal burst are reviewed based on the energy conservation law and the static-dynamic loads superposition theory. The burst energy is provided by static loads including gravitational and abutment stress, and dynamic loads including fault slipping and roof weighting. Studies indicated that the main driving energy source of coal burst occurred in Australian coal mines resulted from elastic energy storage that has been accumulated during the loading process of coal

INVESTIGATION INTO MINE PILLAR DESIGN AND GLOBAL STABILITY USING THE GROUND REACTION CURVE CONCEPT

Pillars form an important support structure in any underground mine. A bulk of the overburden load is borne by the mine pillars. Thus, the strength of pillars has been a subject of detailed research over more than 6 decades. This work has led to the development of largely empirical pillar design formulations that have reduced the risk of pillar failures and mine collapse. Current research, however, has drawn attention to the fact that some of the assumptions used in the development of conventional pillar design methodologies are not always valid. Conventional pillar design methodology assumes that the pillars carry the dead weight of the overburden. This conventional method treats the pillars as passive structures. The limitation of this approach is that the self-supporting capacity of the overburden is not incorporated in pillar design. This suspension theory of pillar design treats the strata-pillar interaction problem as a classic case of static equilibrium, without detailing the interactions of the two structures. Globally, multiple pillar design methods have been developed, based on this suspension theory. Each of these methods approaches the calculation of pillar stability a little differently with respect to material properties, excavation geometries and stress conditions. Most of these design methods are derived empirically and lack a mechanics-based approach. Moreover, there is a lack of a unified pillar design methodology that can be used to design all types of mine pillars using a mechanics-based approach. The Ground Reaction Curve has been used as a means of correlating strata displacements to stress conditions. In addition, the Support Reaction Curve has been used in modeling the response of a support system under load, as a function of support properties and installation time with respect to opening development. In comparing the Ground Reaction Curves and Support Reaction Curves for different support systems, one can evaluate the effectiveness of installed support systems in maintaining the integrity of the excavated area(s). This approach has been widely used in designing secondary (artificial) support systems in both civil tunneling and the mining industry. Encouraged by the successful use of this single method in designing secondary support systems, this research revisits this concept for mine pillar design. This research investigates the utilization of the Ground Reaction Curve and Support Reaction Curve for the design of mine pillar support systems with respect to anticipated pillar loading and opening convergence. In addition, a conceptual three-tier solution to the pillar design problem, using a proper combination of numerical, analytical and data-driven methods is suggested, and a flowchart for the pillar design methodology is proposed. At the focus of this proposed method lies the Ground Reaction Curve (GRC) Concept. This research effort tries to verify the proposed pillar design flowchart using in-mine instrumentation and numerical modeling. For the purpose of this research, a deep longwall coalmine is instrumented to measure changes in pillar stress and associated roof convergence, due to mining activity. Subsequently, numerical models were developed in FLAC3D to model the geomechanical effects of underground longwall mining. The numerical modeling results are validated and calibrated using instrumentation data and a surface subsidence profile. The calibrated numerical models are further used to generate the Ground Reaction Curve for the overburden and Support Reaction Curve for the coal pillar. The comparison of both curves gives a detailed view of the overburden stability with respect to the mine pillar loading, in a more mechanics-based sense. The developed numerical approach can be used in future research and further development of this methodology for various mine types and different pillar support systems

UTVRĐIVANJE PARAMETARA BRZO USPOSTAVLJENE PROTUEKSPLOZIJSKE BRANE

The objective of this paper is to substantiate the method of construction and design parameters of explosion-proof stoppings for the quick and safe remote sealing-off of the sources of complex fires and explosions in coal mines. A new method was designed for the remote erection of explosion-proof stoppings in mine workings and a mathematical model of mass transfer through the body of a stopping made of discrete material. Tactics were improved for the containment of underground fires and explosions due to rapid remote erection of explosion-proof stoppings. The technology of the quick erection of stoppings made of rocks crushed by an explosion for sealing-off of the emergency sections of the mine has been proposed. A computational model and a method for calculating the parameters of explosion-proof stoppings erected by the method of directed explosion have been created. The results of the calculations open the possibility to prepare the means of containment of dust explosions in advance and to improve the tactics of safe containment of explosions and fires.Cilj je rada utvrditi način konstrukcije i projektnih parametara protueksplozijske brane za brzo i sigurno daljinsko izoliranje izvora složenih požara i eksplozija u rudnicima ugljena. Dizajniran je nov način daljinskoga uspostavljanja protueksplozijskih brana u rudarskim radovima i matematički model prijenosa mase kroz tijelo brane od materijala u rasutome stanju. Poboljšan je način za suzbijanje podzemnih požara i eksplozija zahvaljujući brzomu daljinskom uspostavljanju protueksplozijskih brana. Predložena je tehnologija brzoga postavljanja brana od kamena usitnjenoga usmjerenom eksplozijom za izoliranje interventnih dionica rudnika. Izrađen je numerički model i metoda za proračun parametara protueksplozijskih brana uspostavljenih metodom usmjerene eksplozije. Rezultati proračuna otvaraju mogućnost da se unaprijed pripreme sredstva za zadržavanje eksplozivne prašine te da se poboljša metoda sigurnoga suzbijanja eksplozija i požara

Data Management System for a Semiautonomous Shuttle Car for Underground Room and Pillar Coal Mines

In recent years, autonomous solutions in the multidisciplinary field of mining engineering have been an extremely popular applied research topic. This is a result of the increasing demands of society on mineral resources along with the accelerating exploitation of the currently economically viable resources, which lead the mining sector to turn to deeper, more-difficult-to-mine orebodies. An appropriate data management system comprises a crucial aspect of the designing and the engineering of a system that involves autonomous or semiautonomous vehicles. The vast volume of data collected from onboard sensors, as well as from a potential IoT network dispersed around a smart mine, necessitates the development of a reliable data management strategy. Ideally, this strategy will allow for fast and asynchronous access to the data for real-time processing and decision-making purposes as well as for visualization through a corresponding human–machine interface. The proposed system has been developed for autonomous navigation of a coalmine shuttle car and has been implemented on a 1/6th scale shuttle car in a mock mine. It comprises three separate nodes, namely, a data collection node, a data management node, and a data processing and visualization node. This approach was dictated by the large amount of collected data and the need to ensure uninterrupted and fast data management and flow. The implementation of an SQL database server allows for asynchronous, real-time, and reliable data management, including data storage and retrieval. On the other hand, this approach introduces latencies between the data management node and the other two nodes. In general, these latencies include sensor latencies, network latencies, and processing latencies. However, the data processing and visualization module is able to retrieve and process the latest data and make a decision about the next optimal movement of the shuttle car prototype in less than 900 ms. This allows the prototype to navigate efficiently around the pillars without interruptions

A routing protocol for multisink wireless sensor networks in underground coalmine tunnels

Traditional underground coalmine monitoring systems are mainly based on the use of wired transmission. However, when cables are damaged during an accident, it is difficult to obtain relevant data on environmental parameters and the emergency situation underground. To address this problem, the use of wireless sensor networks (WSNs) has been proposed. However, the shape of coalmine tunnels is not conducive to the deployment of WSNs as they are long and narrow. Therefore, issues with the network arise, such as extremely large energy consumption, very weak connectivity, long time delays, and a short lifetime. To solve these problems, in this study, a new routing protocol algorithm for multisink WSNs based on transmission power control is proposed. First, a transmission power control algorithm is used to negotiate the optimal communication radius and transmission power of each sink. Second, the non-uniform clustering idea is adopted to optimize the cluster head selection. Simulation results are subsequently compared to the Centroid of the Nodes in a Partition (CNP) strategy and show that the new algorithm delivers a good performance: Power efficiency is increased by approximately 70%, connectivity is increased by approximately 15%, the cluster interference is diminished by approximately 50%, the network lifetime is increased by approximately 6%, and the delay is reduced with an increase in the number of sinks

Computational fluid dynamics model for controlling dust and methane in underground coalmines

Airborne dust and methane are common problems in the underground coalmines. They pose health and safety risk to mining personnel, and a safety risk to mining equipment as well. In order to prevent these risks air borne dust and methane concentrations must be reduced to within the acceptable levels. In South Africa, the dust and methane concentration in coalmines should not exceed 2.0 mg/m³ and 0.5% per volume, respectively. Mine ventilation is one of the popular ways of controlling both dust and methane. Different ventilation systems have been designed since the history of underground coal mining. Unfortunately, none provides ultimate solution to the dust and methane problem, especially in the most critical areas of the underground coalmine, like blind-end of the heading and last through road. By changing airflow patterns and air velocity, it is possible to obtain an optimum ventilation design that can keep dust and methane within the acceptable levels. Since it is very difficult to conduct experiments in the underground coalmine due to harsh environmental conditions and tight production schedules, the designer made use of the Computational Fluid Dynamics (CFD) modelling technique. The models were then experimentally verified and validated using a scaled down model at University of Pretoria. After verification further numerical analysis was done to in order to device a method for determining optimum fan positions for different heading dimensions. This study proves that CFD can be used to model ventilation system of a scaled down coalmine model. Therefore chances that this might be true for the actual mine are very high but it needs to be investigated. If this is found to be true then CFD modelling will be a very useful tool in coalmine ventilation system research and development.Dissertation (MSc)--University of Pretoria, 2011.Mechanical and Aeronautical Engineeringunrestricte

Mining publication list

"Reports of Investigations (RIs) present the results of original mining health and safety research. They describe individual, short-term studies and include the objective of the research, the materials and techniques used, and the results of tests or experiments. Information Circulars (ICs)present information compiled and analyzed by mining health and safety researchers. They include historical and statistical data, surveys of mining and operating activities, computer program descriptions and user guides, and annotated bibliographies. Technology News is a one-page flyer used to announce a milestone in mining health and safety research, technology ready for transfer to industry, or an opportunity for cooperative research and development. Mining Health and Safety Focus is a newsletter issued periodically on different topics to apprise readers of tangible research results and to expedite the transfer of new technologies to customers. Each section describes what is new or changed in relation to current practices or technologies in mines today." - NIOSHTIC-2Reports of investigations -- Information circulars -- Technology news -- Special publications -- Dissertations -- Mining health and safety update -- Mining safety and health focus -- Flyers -- Hazard identification -- Hazard control -- Final MOA reports -- Outside papers -- Training manuals -- NIOSH numbered publicationsNIOSH ; R. Larry Grayson.NIOSHTIC no. 2000021