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This paper deals with an analysis methodology for evaluating the performance of a coal handling system utilized in a coal based thermal power plant. To simulate the interactions between the subsystems, a stochastic Petri nets technique is used. A licensed software package named Petri module of GRIF were used for computations. This work addresses the performability and cost multi-objective optimization problem for a series-parallel coal handling system of a thermal power plant having subsystem failure dependencies. Performability of subsystems has been examined in relation to variations in failure and repair rates. The Particle Swarm Optimization Technique, which is based on an algorithm discussed, has been used to optimize the results. Based upon the observation and criticality of failure, the subsystems of the coal handling system were given maintenance order priority. A decision support provided at last which will the maintenance personnel™s to take better and informed decision while forming the maintenance policies. It has been observed that the Crusher and Tippler are crucial components that demand the full attention of plant manager. [ABSTRACT FROM AUTHOR]

This paper deals with the management of coal handling operational risks related to the transport of stripped overburden in giant brown coal pit quarries. It aims to identify and analyze the operational risks of currently applied continuous conveyance and to consider alternative transport, i.e., discontinuous transport. The Ishikawa diagram was used to identify the degree of operational risks affecting the net present value in both transport technologies. The operational risks examined were: human factor, suppliers, legislation, technology, environment, and market. Failure Mode and Effects Analysis was then used to evaluate the operational risks of continuous and discontinuous overburden transport technologies. The data for the analyses were obtained by means of a survey among experts in the field. The analyses show that the most significant operational risks of continuous transport are: lower demand for coal, an increase in the investment costs, conveyance breakdowns, the quality of the transported material, and work attitude. In the discontinuous technology, the identified operational risks were: increases in the cost of fuels, road maintenance and costs of tires, low-qualified labor; and work attitude. The comparison of the two examined technologies shows that discontinuous transport technology involves more operational risks than the continuous one. [ABSTRACT FROM AUTHOR]

A dragline is the largest mobile equipment on earth, and it is called the "kingpin" of any mine site. In this present investigation, a case of premature failure of a coal-handling dragline is discussed. Failure occurred in a linked component known as "thimble," which connects the A-frame and the vertical mast of the dragline. The thimble was broken into two halves and caused the entire front structures of the dragline to collapse. Failure investigation was performed through visual examination, chemical analysis, metallography, mechanical property evaluation and fractography. [ABSTRACT FROM AUTHOR]

Abstract Burning coal is known to have environmental costs; this paper demonstrates that the environmental costs of storing and handling coal are also sizable. We find that a 10% increase in the coal stockpiles held by U.S. power plants results in a 0.09% increase in average PM 2.5 concentration levels within 25 miles of these plants. Unlike most sources of variation in local air pollution, coal storage and handling impacts PM 2.5 but not other pollutants such as SO 2 and NO 2. Consequently, using coal stockpiles as an instrument, we show that a 10% increase in PM 2.5 causes a 1.1% (3.2%) increase in average adult (infant) mortality rates. Using a value of statistical life approach, our estimates indicate that a one ton increase in coal stockpiles results in local air pollution costs of $197. Economic policies that subsidize coal stockpiles highlight the importance of implementing environmental regulations specifically directed at coal storage and handling. [ABSTRACT FROM AUTHOR]

From an environmental and economic perspective coal handling and preparation plants are under increasing pressure to reduce their consumption of fresh water and to strictly follow tight standards and specifications to release process water. Many coal washeries use recycled water as part of their water management strategy, which contains a higher content of inorganic electrolytes. In this study, five water samples from four coal washeries were analysed. The effect of methyl isobutyl carbinol (MIBC) frother was tested to evaluate the influence of water composition on the persistence of bubble pairs and the effectiveness of MIBC in preventing coalescence in a quiescent and dynamic environment, respectively. It was shown that the coalescence time was longer for bubbles in water samples of higher ionic strengths. However the effectiveness of an addition of MIBC was weakened in these solutions. It was also established that the water samples with higher ion content produced smaller bubbles in a laboratory flotation cell. In contrast to the binary coalescence experiment, the addition of MIBC appeared to be more effective in reducing the bubble size whilst a higher electrolyte concentration is present. The sensitivity of the effects of inorganic electrolytes on the bubble-bubble interactions suggests that coal washeries may benefit in monitoring the quality of the water employed in the flotation circuit. [ABSTRACT FROM AUTHOR]

Abstract: The mobilities of major and trace elements in stockpiled sub-bituminous coal and the coastal sand on which the stockpile has been built have been evaluated by batch leaching tests using demineralised water and controlled-pH (acidic) solutions. The results were compared with those from column leaching tests on the coal with similar liquids, and with a column test in which the coal was placed above a bed of the coastal sand material. Batch testing showed that most trace elements, especially As, Cr, Cu, Mo, Pb, Sb, Sr, V and Zn, were released in higher concentrations from the sand than from the coal. Some elements were released in greater concentrations from the coal (although values were still low), while a few were released in low but approximately equal concentrations from both materials. Comparison of the column and batch test results suggests that most of the elements in the leachate from the column in which coal was underlain by sand were derived from the sand component. The column tests further indicate that concentrations of many elements mobilised from the coal are likely to be reduced by interactions associated with percolation through the sand bed. [Copyright &y& Elsevier]

Australian construction, mining and services contractor Thiess Pty Ltd has won two new contracts worth approximately A$220 million from the BHP Billiton Mitsubishi Alliance for construction work on the Caval Ridge Mine Project in the Bowen Basin in Central Queensland, Australia. [Copyright &y& Elsevier]