Indian Coals vis-a-vis Spontaneous Heating Problems

The paper highlights the alarming problem of spontaneous heating in mines so that immediate remedies can be identified and implemented. The status of spontaneous heating in the last four decades has been summarized showing the changing trend of spontaneous heating occurrences in India. The paper also deals with some new methods of dealing mine fires which so far have not been implemented in India but have great potential

Reversal of underground mine ventilation

Reversal of main ventilation is one of the important means to isolate a fire during emergency. In America, it has been reported that by fan reversal lives have been saved in underground coal mine. Indian coal mines have so far not come forward to adopt this method. Not much research work has so far been carried out in India. This paper deals with international review of the work carried out in other countries. Law relating to reversal of ventilation in different countries of the world is discussed. The effect of reversal on goaf gases and adjustment of ventilating flow is also outlined

Living instruments and theoretical terms : Xenografts as measurements in cancer research

I discuss the relationship between theoretical terms and measuring devices using a very peculiar example from biomedical research: cancer transplantation models. I do so through two complementary comparisons. I first show how a historical case study can shed light on a similar case from contemporary biomedical research. But I also compare both to a paradigmatic case of measurement in the physical sciences -- thermometry -- which reveals some of the most relevant epistemological issues. The comparison offers arguments for the recent debate on the operational definition of Cancer Stem Cells, and thereby suggests the relevance of a comparative approach in the history and philosophy of science

A spatio-temporal analysis of performance and prospects

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Significant improvement in effectiveness of nitrogen infusion technology for control of fire by dynamic balancing of pressure —A case study of powered support longwall face

A large number of powered supports and other equipment costing millions of rupees were trapped due to sudden loading and collapse of part of the roof of longwall panel No. 3 in Samla Seam (R III / II) of Kottadih colliery, Raniganj coalfields, India. In fact 55 out of 83 chock shields were badly damaged and subsequently heating was detected in the panel which quickly aggravated, leading to sealing of the panel. Therefore, at that stage, the most urgent need was to bring the fire under control as quickly as possible, preferably within three weeks time, and without allowing the temperature to exceed 50°C at the face, as it could have caused heavy leakage of hydraulic fluid due to failure of the “O” rings of the powered supports. Both the aforesaid objectives were achieved by nitrogen infusion along with dynamic balancing of pressure. Liquid and gaseous nitrogen were infused in the affected panel through boreholes and pipes already laid in the mine. The panel was then successfully reopened after 19 days of sealing, and it was possible to keep the temperature of the face below 40°C throughout the operation. This, therefore, paved the way for safe recovery of all the healthy supports and other equipment worth over Rs 400 million. In essence, the paper briefly highlights salient features of the fire problem, and the results of investigations undertaken before and after implementation of various control measures adopted in the mine. Successful control of fire even under critical geo-mining conditions has led to the conclusion that liquid nitrogen (LN2) in conjunction with dynamic balancing of pressure has the potential to control underground mine fire quickly and safely

Dynamic Balancing of Pressure for Control of Fire in Underground Coal Mines

The conventional methods of pressure balancing techniques have been classified into two categories viz., static and active and the concept of dynamic balancing of pressure introduced. Theory and practice of dynamic balancing of pressure have been explained and illustrated with details of a case study where fire was successfully controlled by this method. Relative advantages of the method have also been discussed. The technique needs minimal expenditure on material and equipment as the main emphasis is laid on utilization of available ventilation pressure in the mine for pressure balancing. The method is general enough for quick and economical application elsewhere under variety of underground conditions

Fighting mine fires using gases with particular reference to nitrogen

The practice of pumping gases which inhibit combustion for purposes of controlling or extinguishing mine fires is now universally accepted. The practice has been used many times in coal mines in India and the experiences are reviewed. The procedures relating to a membrane based nitrogen generator and to a combustion gases generator are described. The physical properties, practical requirements and economic implications of using different gases is briefly reviewed. Some aspects of the practice as related to mine fires in certain collieries in other countries are dealt with

Study on Application on Fire Suppression Techniques Under Dynamic Fire Conditions

A mine fire model gallery has been designed and constructed on the premises of the Central Mining Research Institute, Dhanbad, India to perform systematic in-depth studies on various aspects of mine fires. The gallery is 65.5 m long and 5.86 m2 in cross-section and it is divided into firing and non-firing zones. It is equipped with a computer-aided online telemonitoring system that has 130 sensors, two data loggers and computer peripherals for continuous recording of various fire parameters. A fan to generate airflow through the gallery has been installed at its end. Two sliding doors and one rolling shutter were also provided for sealing and regulation of airflow. Two sets of experiments have been carried out in the model gallery maintaining air velocity of 1 and 1.5 m/s through it. In the experiments, the inner sides of the firing zone, 22 m in length, were lined with a thin layer (8–10 cm thick) of coal slabs. Two fire suppression techniques viz. flushing of liquid nitrogen (LN2) and infusion of high pressure high stability (HPHS) nitrogen foam were tried to quantify their effectiveness under dynamic fire conditions. The paper addresses important design features of the gallery, its instrumentation system, the experimental procedure adopted and important findings from the experiments. It has been observed that the intensity of the fire was very high after one hour of its initiation and continued for 3–4 hours. During the period, frequent backlash with smoke and flame was noticed. The efficacy of the fire suppression techniques has been assessed in terms of reduction in temperature, generation rate of CO2 and CO, and heat release rate. The study reveals that high pressure high stability (HPHS) nitrogen foam is more effective in controlling open fires than liquid nitrogen is